Cardiovascular System

455 questions

All types455 Multiple choice237 Matching117 Ordering101

Progressive dyspnea and persistent chills over the past week prompt the hospitalization of a $34$ -year-old woman with a well-documented history of injection drug use. Initial blood cultures are drawn, and she is started on empiric intravenous vancomycin and cefepime. On the second day of admission, the nursing staff calls for urgent evaluation due to a sudden decline in her mental status. Vital signs show a temperature of $38.8^\circ C$ ( $101.8^\circ F$ ), blood pressure of $72/40$ mmHg, heart rate of $134$ /min, and respiratory rate of $28$ /min. Her extremities are cool with thread-like peripheral pulses. Cardiac auscultation reveals tachycardia with a soft first heart sound ( $S_1$ ), a prominent third heart sound ( $S_3$ ), and a short, early diastolic decrescendo murmur best heard along the left sternal border. Lung auscultation demonstrates bilateral crackles extending to the mid-lung fields along with scattered expiratory wheezes. A bedside echocardiogram reveals a $1.6$ -cm highly mobile echodensity attached to the aortic valve, accompanied by severe leaflet destruction and massive retrograde flow into a normal-sized left ventricle. Which of the following is the most appropriate next step in the management of this patient?

Consult cardiothoracic surgery for emergent aortic valve replacement

Administer intravenous methylprednisolone and nebulized albuterol

Initiate a continuous norepinephrine infusion and delay surgical intervention until blood cultures are sterile

Transport to radiology for emergent computed tomography angiography of the chest

Insert an intra-aortic balloon pump to provide mechanical hemodynamic support

Show answer & explanation

Answer: Consult cardiothoracic surgery for emergent aortic valve replacement

Answer

The most appropriate next step is to consult cardiothoracic surgery for emergent aortic valve replacement.

The correct answer is to consult cardiothoracic surgery for emergent aortic valve replacement. This patient has infective endocarditis complicated by acute, massive aortic regurgitation. The acute destruction of the aortic valve leads to a massive regurgitant volume entering a normal-sized, non-compliant left ventricle. This causes a precipitous rise in left ventricular end-diastolic pressure, leading to acute pulmonary edema (manifested by crackles and wheezing) and profound cardiogenic shock (hypotension, cool extremities, altered mental status). In the setting of infective endocarditis, the development of heart failure or cardiogenic shock is an absolute indication for emergent surgical intervention. Medical management with vasopressors or inotropes is insufficient to manage the severe mechanical derangement, and surgery must not be delayed.

Step-by-Step Solution

Analyze the patient's physical examination and vital signs.

The patient is in cardiogenic shock (blood pressure

72/40

mmHg, cool extremities, altered mental status) with signs of acute heart failure (crackles, wheezing,

S_3

Identifying hemodynamic instability is the critical first step in triage and management.

Correlate the physical exam findings with the echocardiogram.

The short early diastolic murmur and soft

S_1

correlate with the echocardiographic finding of acute, massive aortic regurgitation secondary to a

1.6

-cm vegetation.

Acute aortic regurgitation presents differently than chronic regurgitation; the rapid rise in left ventricular end-diastolic pressure cuts the diastolic murmur short and prematurely closes the mitral valve (soft

S_1

Determine the optimal management for infective endocarditis with mechanical collapse.

Medical management alone is insufficient. The patient requires emergent surgical source control and mechanical correction.

Heart failure and cardiogenic shock due to valvular destruction are absolute indications for emergent surgery in infective endocarditis.

Key Concept

Absolute indications for emergent surgery in infective endocarditis include heart failure, cardiogenic shock, perivalvular extension (abscess/fistula), and persistent infection despite adequate antibiotic therapy.

Estimated Time:1m 30s

Question 422Question →

An 68-year-old woman is brought to the emergency department by ambulance due to sudden, severe chest pain that began 45 minutes ago. She describes the pain as "tearing" and radiating directly to her interscapular region. En route to the hospital, the patient had a brief episode of syncope. Her medical history includes long-standing hypertension and a 40-pack-year smoking history. Upon arrival, she is lethargic and diaphoretic. Vital signs are temperature 36.8°C (98.2°F), heart rate 122/min, blood pressure 78/50 mm Hg in the right arm and 82/54 mm Hg in the left arm, and respiratory rate 24/min. Pulse oximetry shows 95% on room air. Physical examination reveals distended jugular veins while sitting at a 45-degree angle. Lung fields are clear to auscultation bilaterally. Cardiac auscultation reveals a faint early diastolic decrescendo murmur at the right upper sternal border. The peripheral pulses are weak but symmetric. An electrocardiogram demonstrates sinus tachycardia with low-voltage QRS complexes. Which of the following is the most appropriate next step in management?

Bedside transthoracic echocardiography

Computed tomography angiography of the chest

Intravenous labetalol administration

Intravenous furosemide administration

Immediate bedside pericardiocentesis

Show answer & explanation

Answer: Bedside transthoracic echocardiography

Answer

Bedside transthoracic echocardiography

The correct answer is bedside transthoracic echocardiography. This patient presents with classic signs of an acute Type A aortic dissection (tearing chest pain, new aortic regurgitation murmur). However, her clinical picture is complicated by obstructive shock, evidenced by profound hypotension, jugular venous distention with clear lungs, syncope, and low-voltage QRS complexes. These findings strongly suggest the dissection has ruptured into the pericardial space, causing acute cardiac tamponade. In a hemodynamically unstable patient, the standard diagnostic test of choice (CT angiography) is unsafe. The next best step is bedside transthoracic echocardiography (TTE), which can rapidly confirm the presence of a pericardial effusion and often visualize the dissection flap, facilitating immediate transfer to the operating room for definitive surgical repair.

Step-by-Step Solution

Analyze the primary presentation

Sudden, severe tearing chest pain radiating to the back with a new early diastolic murmur (aortic regurgitation) indicates an acute Type A ascending aortic dissection.

Recognizing the classic clinical syndrome of aortic dissection is the first diagnostic step.

Evaluate the patient's hemodynamic status and secondary symptoms

The patient has hypotension, tachycardia, jugular venous distention, clear lungs, syncope, and low-voltage QRS complexes on ECG.

These findings point to obstructive shock caused by cardiac tamponade, a known and highly lethal complication of Type A dissection when the aorta ruptures into the pericardial space.

Determine the safest diagnostic approach for an unstable patient

Bedside transthoracic echocardiography is selected to immediately visualize the pericardial effusion and potential intimal flap without leaving the resuscitation bay.

Transporting a hemodynamically unstable patient to a CT scanner is contraindicated.

Key Concept

Management of acute Type A aortic dissection complicated by cardiac tamponade in a hemodynamically unstable patient requires immediate bedside echocardiography.

Estimated Time:1m 15s

Question 423Question →

A $68$ -year-old man is evaluated in the cardiac intensive care unit for worsening respiratory distress and lethargy. He was admitted two days ago after an acute anterior ST-segment elevation myocardial infarction and underwent successful primary percutaneous coronary intervention with stent placement in the left anterior descending artery.

Current vital signs are as follows:

Parameter	Value
Temperature	$37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ )
Blood pressure	$82/54\text{ mm Hg}$
Heart rate	$118/\text{min}$
Respiratory rate	$28/\text{min}$
Oxygen saturation	$84\%$ (on $15\text{ L/min}$ via non-rebreather mask)

Physical examination reveals a somnolent, diaphoretic man in severe respiratory distress. Jugular venous pressure is elevated at $12\text{ cm H}_2\text{O}$ . Cardiac auscultation reveals a regular tachycardia and a prominent $S_3$ gallop, without murmurs. Pulmonary examination shows diffuse bilateral crackles extending up to the upper lung fields. His extremities are cool to the touch with faint peripheral pulses.

Arterial blood gas analysis on

15\text{ L/min}

supplemental oxygen reveals:

Parameter	Value	Reference Range
$\text{pH}$	$7.22$	$7.35 - 7.45$
$\text{PaCO}_2$	$40\text{ mm Hg}$	$35 - 45\text{ mm Hg}$
$\text{PaO}_2$	$52\text{ mm Hg}$	$75 - 105\text{ mm Hg}$
Bicarbonate ( $\text{HCO}_3^-$ )	$16\text{ mEq/L}$	$22 - 28\text{ mEq/L}$

Which of the following is the most appropriate next step in the management of this patient?

Endotracheal intubation and mechanical ventilation

Intravenous sodium bicarbonate infusion

Administration of nebulized albuterol and intravenous methylprednisolone

Initiation of intravenous levofloxacin and azithromycin

Initiation of continuous renal replacement therapy

Show answer & explanation

Answer: Endotracheal intubation and mechanical ventilation

Answer

Endotracheal intubation and mechanical ventilation

The patient is in cardiogenic shock (hypotension, cool extremities, lethargy) complicated by acute pulmonary edema. The arterial blood gas shows a severe metabolic acidosis with a

\text{PaCO}_2

40\text{ mm Hg}

. According to Winter's formula (

\text{Expected PaCO}_2 = 1.5 \times [\text{HCO}_3^-] + 8 \pm 2

), the expected

\text{PaCO}_2

should be

30 - 34\text{ mm Hg}

. A measured

\text{PaCO}_2

40\text{ mm Hg}

is inappropriately high, indicating a superimposed primary respiratory acidosis caused by respiratory muscle fatigue. Given his somnolence, inability to protect his airway, and severe hypoxemia refractory to high-flow oxygen, immediate endotracheal intubation and mechanical ventilation are definitively required to secure the airway and decrease the work of breathing.

Step-by-Step Solution

Interpret the vital signs and physical examination findings.

The patient has hypotension (

82/54\text{ mm Hg}

), tachycardia, somnolence, an

S_3

gallop, and diffuse crackles, indicating severe cardiogenic shock with acute pulmonary edema.

Recognizing the underlying hemodynamic collapse is required to interpret the laboratory values contextually.

Analyze the arterial blood gas values.

The

\text{pH}

7.22

with a low bicarbonate of

16\text{ mEq/L}

, indicating a primary metabolic acidosis, likely lactic acidosis due to poor tissue perfusion.

Identifying the primary acid-base disorder dictates the next step in calculating expected compensation.

Calculate the expected respiratory compensation using Winter's formula.

\text{Expected PaCO}_2 = (1.5 \times 16) + 8 = 32 \pm 2\text{ mm Hg}

This calculation reveals whether the respiratory system is compensating adequately for the metabolic acidosis.

Compare expected and actual

\text{PaCO}_2

The actual

\text{PaCO}_2

40\text{ mm Hg}

, which is significantly higher than the expected

30-34\text{ mm Hg}

. This indicates a concomitant primary respiratory acidosis.

A 'normal'

\text{PaCO}_2

40\text{ mm Hg}

in the setting of severe metabolic acidosis is abnormal and signals severe respiratory muscle fatigue.

Determine the next best step in management.

Immediate endotracheal intubation and mechanical ventilation.

The patient is somnolent with severe hypoxemia (

\text{SpO}_2\ 84\%

15\text{ L/min}

) and impending respiratory failure; the airway must be secured before further interventions.

Key Concept

Differentiating simple metabolic acidosis from a mixed metabolic and respiratory acidosis using Winter's formula to recognize impending respiratory failure in cardiogenic shock.

Estimated Time:1m 30s

Question 424Question →

A series of adult patients present for routine cardiovascular evaluation. For each described auscultatory profile and maneuver response, select the most appropriate underlying structural heart disease.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The clinical profiles match Mitral valve prolapse, Aortic stenosis, Aortic regurgitation, and Tricuspid regurgitation, respectively.

Each murmur's timing, specific location, and dynamic response perfectly aligns with the mechanical consequences of its corresponding structural heart disease.

Step-by-Step Solution

Evaluate the murmur with a mid-systolic click and response to Valsalva.

Matches Mitral valve prolapse.

Decreasing preload via Valsalva causes an earlier prolapse, leading to an earlier and longer murmur.

Evaluate the crescendo-decrescendo systolic murmur at the right upper sternal border.

Matches Aortic stenosis.

Radiation to the carotids and decreased intensity with increased afterload (handgrip) are classic distinguishing features.

Evaluate the early diastolic decrescendo murmur that worsens with leaning forward.

Matches Aortic regurgitation.

This anatomical positioning optimally aligns the aortic outflow tract with the chest wall to hear the regurgitant jet.

Evaluate the holosystolic murmur at the left lower sternal border that increases with inspiration.

Matches Tricuspid regurgitation.

Carvallo's sign (augmentation with inspiration) specifically identifies right-sided murmurs.

Key Concept

Clinical recognition and dynamic auscultation of valvular heart diseases.

Estimated Time:1m 30s

Question 425Question →

An internal medicine ward nurse urgently pages the on-call physician to evaluate a $68$ -year-old man whose respiratory status has rapidly deteriorated over the past $30$ minutes. The patient was admitted two days ago for a non-ST-segment elevation myocardial infarction and has been managed medically. He now reports severe, suffocating shortness of breath.

Temperature is $37.1^\circ$ C ( $98.8^\circ$ F), blood pressure is $210/115$ mmHg, heart rate is $118$ /min, respiratory rate is $32$ /min, and oxygen saturation is $82\%$ on room air. Physical examination reveals a profoundly diaphoretic man sitting bolt upright and using accessory muscles of respiration. Auscultation of the lungs reveals diffuse, high-pitched expiratory wheezing and fine crackles extending to the mid-lung fields bilaterally. Cardiovascular examination demonstrates a regular tachycardia with a prominent $S_3$ gallop. Jugular venous distention is present up to the angle of the mandible while sitting.

Bedside arterial blood gas analysis on room air shows:
* pH: $7.15$
* $PaCO_2$ : $50$ mmHg
* $HCO_3^-$ : $17$ mEq/L
* $PaO_2$ : $50$ mmHg

Which of the following is the most appropriate initial step in the management of this patient?

Administration of an intravenous sodium bicarbonate infusion

Administration of intravenous methylprednisolone and continuous nebulized albuterol

Application of noninvasive positive pressure ventilation and initiation of intravenous nitroglycerin

Administration of a 1000 mL intravenous fluid bolus and broad-spectrum antibiotics

Emergent transport to the radiology suite for computed tomography pulmonary angiography

Show answer & explanation

Answer: Application of noninvasive positive pressure ventilation and initiation of intravenous nitroglycerin

Answer

Application of noninvasive positive pressure ventilation and initiation of intravenous nitroglycerin

The correct answer is the application of noninvasive positive pressure ventilation (NPPV) and initiation of intravenous nitroglycerin. This patient is experiencing acute decompensated heart failure (ADHF) characterized by 'flash' pulmonary edema and an acute hypertensive emergency following a recent myocardial infarction. The sudden sympathetic surge increases peripheral vascular resistance (afterload), which the failing left ventricle cannot overcome, leading to rapid fluid transudation into the alveoli. This causes severe hypoxia, crackles, an

S_3

gallop, and peribronchial edema presenting as wheezing ('cardiac asthma'). The arterial blood gas demonstrates a severe mixed acid-base disorder: a high anion gap metabolic acidosis (likely lactic acidosis from tissue hypoxia/hypoperfusion) and a concurrent respiratory acidosis. Based on Winter's formula, the expected

PaCO_2

1.5 \times 17 + 8 = 33.5 \pm 2

mmHg. The measured

PaCO_2

50

mmHg indicates respiratory failure due to muscle fatigue. The most appropriate initial step is NPPV to rapidly improve oxygenation and decrease the work of breathing, combined with intravenous nitroglycerin to rapidly reduce afterload and preload.

Step-by-Step Solution

Analyze the patient's presentation and vital signs.

The patient has severe hypertension (

210/115

mmHg), respiratory distress, hypoxia, an

S_3

gallop, JVD, and bilateral crackles with wheezes.

To establish the primary clinical syndrome, which is acute decompensated heart failure presenting as 'flash' pulmonary edema with cardiac asthma.

Interpret the arterial blood gas results using Winter's formula.

Expected

PaCO_2 = (1.5 \times 17) + 8 = 33.5 \pm 2

. Actual

PaCO_2

(

50

mmHg) is significantly higher than expected, indicating a superimposed primary respiratory acidosis alongside the metabolic acidosis.

To identify if the patient is adequately compensating or experiencing impending respiratory failure due to severe pulmonary edema.

Determine the optimal immediate intervention based on the diagnosis and severity.

The patient requires immediate afterload reduction and respiratory support.

Noninvasive positive pressure ventilation (NPPV) decreases the work of breathing and improves oxygenation, while IV nitroglycerin rapidly reduces the severe hypertension (afterload) driving the fluid transudation.

Key Concept

Management of acute decompensated heart failure (flash pulmonary edema) presenting with acute hypertension, mixed acid-base disorder, and cardiac asthma.

Question 426Question →

A 65-year-old man is brought to the emergency department by his adult daughter due to severe shortness of breath that has progressively worsened over the past 24 hours. He has a history of ischemic cardiomyopathy, type 2 diabetes mellitus, and a 40-pack-year smoking history. The patient is visibly distressed, diaphoretic, and intermittently confused due to hypoxia. His daughter provides a legally valid advance directive naming her as the sole healthcare proxy. A few minutes later, the patient's estranged wife arrives at the bedside and demands to make his medical decisions.

Vital signs are temperature $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure $170/95$ mm Hg, pulse $115$ /min, and respirations $28$ /min. Oxygen saturation is 84% on room air. Jugular venous distention is present to the angle of the mandible while sitting upright. Lung auscultation reveals bilateral crackles extending to the mid-lung fields and widespread expiratory wheezing. Cardiac auscultation demonstrates a regular tachycardia with a prominent S3 gallop. There is 2+ bilateral lower extremity pitting edema.

Arterial blood gas on room air shows:
pH: $7.25$
pCO $_2$ : $60$ mm Hg
pO $_2$ : $50$ mm Hg
HCO $_3^-$ : $26$ mEq/L

White blood cell count is $8,500/\text{mm}^3$ .

Which of the following is the most appropriate next step in the management of this patient?

Initiate noninvasive positive pressure ventilation and administer intravenous furosemide

Administer inhaled albuterol, systemic corticosteroids, and low-flow supplemental oxygen

Obtain blood cultures and initiate empiric intravenous vancomycin and piperacillin-tazobactam

Administer intravenous sodium bicarbonate to correct the metabolic derangement

Obtain consent for potential endotracheal intubation from the patient's estranged wife

Show answer & explanation

Answer: Initiate noninvasive positive pressure ventilation and administer intravenous furosemide

Answer

Initiate noninvasive positive pressure ventilation and administer intravenous furosemide

The patient presents with classic signs of acute decompensated heart failure (ADHF), characterized by volume overload (jugular venous distention, peripheral edema) and cardiogenic pulmonary edema (hypoxia, crackles, S3 gallop). The widespread expiratory wheezing represents 'cardiac asthma,' which occurs when fluid accumulates in the interstitial space and causes peribronchial airway narrowing, mimicking primary bronchospasm. The arterial blood gas demonstrates acute uncompensated respiratory acidosis secondary to fluid accumulation in the alveoli impairing ventilation. The most appropriate immediate management is diuresis with an intravenous loop diuretic (e.g., furosemide) to reduce intravascular volume, coupled with noninvasive positive pressure ventilation (NPPV). NPPV is highly effective in ADHF because it improves oxygenation, decreases the work of breathing, and increases intrathoracic pressure, which favorably reduces both left ventricular preload and afterload.

Step-by-Step Solution

Analyze the patient's clinical presentation and physical exam findings.

The patient has signs of severe volume overload (jugular venous distention, peripheral edema) and cardiogenic pulmonary edema (hypoxia, crackles, S3 gallop, and wheezing).

Identifying the primary clinical syndrome is necessary to differentiate between cardiac and pulmonary etiologies of acute dyspnea.

Evaluate the arterial blood gas (ABG) results.

The ABG shows an acidemic pH (

7.25

) driven by an elevated pCO

_2

(

60

mm Hg) with a normal HCO

_3^-

(

26

mEq/L).

This confirms an acute uncompensated respiratory acidosis caused by poor alveolar gas exchange from pulmonary edema, ruling out a primary metabolic acidosis.

Identify the appropriate surrogate decision-maker in the event the patient becomes incapacitated.

The daughter is the sole legally appointed healthcare proxy.

An advance directive explicitly naming a proxy supersedes default next-of-kin laws, even if the patient is legally married.

Determine the most appropriate immediate medical intervention.

The correct intervention is diuresis with loop diuretics (e.g., intravenous furosemide) and respiratory support with noninvasive positive pressure ventilation (NPPV).

These therapies rapidly decrease left ventricular preload and afterload while simultaneously recruiting fluid-filled alveoli to improve oxygenation.

Key Concept

Diagnosis and acute management of acute decompensated heart failure presenting with cardiogenic pulmonary edema and cardiac asthma.

Question 427Question →

A 62-year-old man is brought to the emergency department complaining of sudden-onset, severe, tearing chest pain that radiates to his back. His blood pressure is 210/115 mm Hg in the right arm and 170/95 mm Hg in the left arm. His pulse is 115/min and regular. Physical examination reveals a new decrescendo diastolic murmur at the right upper sternal border. An electrocardiogram shows non-specific ST-segment changes. Arrange the following steps in the most appropriate sequential order for the evaluation and management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for managing suspected acute aortic dissection is to first control heart rate with a beta-blocker, then control blood pressure with a vasodilator, followed by definitive imaging, and finally surgical consultation.

The correct sequence prioritizes preventing the propagation of the dissection flap. Intravenous beta-blockers must be given first to decrease the heart rate and left ventricular contractility (reducing

dP/dt

). Only after the heart rate is controlled should vasodilators be added to reach a target systolic blood pressure of 100-120 mm Hg. Once hemodynamically stabilized, definitive imaging (CT angiography) is performed, which then guides the need for emergent surgical repair.

Step-by-Step Solution

Recognize the clinical presentation of acute aortic dissection.

The tearing chest pain, asymmetric blood pressures, and new aortic regurgitation murmur strongly suggest an ascending (Type A) aortic dissection.

Accurate initial recognition guides the immediate necessity of strict hemodynamic control prior to other interventions.

Select the initial pharmacological intervention.

Intravenous esmolol (a beta-blocker) is administered first.

Decreasing the heart rate and left ventricular contractility reduces aortic wall shear stress and prevents propagation of the dissection flap.

Select the subsequent pharmacological step.

Intravenous nitroprusside is administered next.

Vasodilators further lower blood pressure but must strictly be given after beta-blockade to prevent reflex tachycardia.

Identify the appropriate diagnostic imaging.

Computed tomography angiography of the aorta is performed.

Imaging definitively confirms the diagnosis and anatomical extent (Stanford type A vs. B) after hemodynamics are stabilized.

Determine the definitive treatment.

Cardiothoracic surgery consultation is obtained.

Ascending aortic dissections require immediate operative intervention to prevent rupture and mortality.

Key Concept

In the acute management of suspected aortic dissection, sequential hemodynamic control requires the administration of an intravenous beta-blocker to reduce heart rate and shear stress before using a vasodilator to lower blood pressure.

Question 428Question →

Emergency medical services bring a $73$ -year-old woman to the resuscitation bay after she was found lethargic and struggling to breathe at home. According to her daughter, the patient has a history of type II bipolar disorder, primary hypothyroidism, and tobacco use disorder ( $35$ pack-years). For the past three days, she has been sleeping in a recliner due to worsening orthopnea.

On arrival, her temperature is $36.2^\circ \text{C}$ ( $97.2^\circ \text{F}$ ), blood pressure is $76/48 \text{ mm Hg}$ , pulse is $124/\text{min}$ , and respiratory rate is $28/\text{min}$ . Oxygen saturation is $85\%$ on room air.

Physical examination reveals a somnolent, mottled patient with cool extremities. The external jugular veins are engorged up to the angle of the jaw while the patient is positioned at a $45^\circ$ angle. Auscultation of the chest demonstrates diffuse, prolonged expiratory wheezing and coarse crackles at both lung bases. Cardiac auscultation reveals a rapid, regular rhythm with a prominent $S_3$ gallop. There is $2+$ pitting edema in the lower extremities.

Laboratory studies reveal:
Leukocyte count: $11,200/\text{mm}^3$
Lactate: $4.5 \text{ mmol/L}$
Thyroid-stimulating hormone (TSH): $2.4 \text{ mU/L}$ (normal: $0.5-5.0 \text{ mU/L}$ )
Free thyroxine (T4): $0.7 \text{ ng/dL}$ (normal: $0.9-1.7 \text{ ng/dL}$ )
Troponin I: $0.05 \text{ ng/mL}$ (normal $< 0.03 \text{ ng/mL}$ )

Arterial blood gas analysis on room air shows:
pH: $7.25$
$\text{PaCO}_2$ : $30 \text{ mm Hg}$
$\text{PaO}_2$ : $55 \text{ mm Hg}$
$\text{HCO}_3^-$ : $13 \text{ mEq/L}$

An electrocardiogram shows sinus tachycardia with low QRS voltage in the limb leads and non-specific ST-segment changes.

Which of the following is the most appropriate initial management step for this patient?

Initiation of a norepinephrine infusion and focused cardiac ultrasonography

Administration of continuous nebulized albuterol and intravenous methylprednisolone

Immediate transfer to the radiology department for a contrast-enhanced chest scan

Intravenous bolus of levothyroxine and hydrocortisone administration

Infusion of an alkalinizing agent to correct an isolated metabolic acidosis

Show answer & explanation

Answer: Initiation of a norepinephrine infusion and focused cardiac ultrasonography

Answer

The correct management is the initiation of a norepinephrine infusion and focused cardiac ultrasonography.

The correct answer identifies the need for immediate vasopressor support and bedside diagnostic imaging. This patient is in cardiogenic shock, characterized by profound hypotension, evidence of poor end-organ perfusion (altered mental status, cool/mottled extremities, lactic acidosis), and volume overload (elevated JVP, pulmonary edema,

S_3

gallop). Norepinephrine is the initial vasopressor of choice for undifferentiated shock and cardiogenic shock with severe hypotension. Focused cardiac ultrasonography (point-of-care ultrasound) is the gold standard next step to rapidly determine the etiology (e.g., severe ischemic left ventricular dysfunction, acute valvular regurgitation, or pericardial tamponade) without moving the unstable patient.

Step-by-Step Solution

Evaluate the patient's hemodynamic status and physical exam findings.

The patient exhibits frank shock (blood pressure

76/48 \text{ mm Hg}

, cool and mottled extremities, lethargy) coupled with classic signs of left and right heart failure (pulmonary crackles,

S_3

gallop, jugular venous distention).

Identifying the phenotype of shock is critical. The combination of pump failure signs and poor perfusion definitively points to cardiogenic shock.

Differentiate confounding pulmonary and endocrine presentations.

The wheezing is identified as cardiac asthma rather than a COPD exacerbation. The low T4 with normal TSH is identified as euthyroid sick syndrome, ruling out myxedema coma.

Multisystem organ dysfunction in shock frequently causes secondary laboratory and physical abnormalities that can mimic primary diseases.

Calculate the expected respiratory compensation for the metabolic acidosis.

Using Winter's formula (

1.5 \times 13 + 8 = 27.5 \pm 2

), the expected

\text{PaCO}_2

25.5-29.5 \text{ mm Hg}

. The actual

\text{PaCO}_2

30 \text{ mm Hg}

, indicating a concurrent respiratory acidosis.

Determining the presence of respiratory failure dictates whether airway intervention might be imminently required, confirming the severity of the pulmonary edema.

Determine the immediate intervention.

Stabilize the mean arterial pressure using a first-line vasopressor (norepinephrine) while simultaneously performing a bedside echocardiogram.

Hemodynamic stabilization takes precedence, and point-of-care ultrasound safely identifies the precise cardiac pathology without risking the patient's life in the radiology suite.

Key Concept

Cardiogenic shock diagnosis and immediate management

Question 429Question →

An emergency medical services team brings a $76$ -year-old male to the hospital at $2:00\text{ AM}$ due to abrupt, severe respiratory distress. The patient has a known history of ischemic heart disease and hypertension. His wife reports that he woke up suddenly, gasping for air, and has been expectorating frothy, pink-tinged sputum. Over the preceding week, he had transitioned to sleeping in a living room recliner due to worsening dyspnea when lying flat. He is a lifetime non-smoker. Upon arrival, his vital signs include a temperature of $36.8^\circ\text{C}$ ( $98.2^\circ\text{F}$ ), blood pressure of $185/105\text{ mmHg}$ , a regular heart rate of $115\text{/min}$ , and a respiratory rate of $28\text{/min}$ . Pulse oximetry indicates an oxygen saturation of $86\%$ on room air. The patient appears highly anxious, diaphoretic, and is leaning forward while utilizing accessory respiratory muscles. Lung auscultation is notable for loud, diffuse expiratory wheezes bilaterally, alongside faint crackles restricted to the posterior bases. Cardiac examination reveals a distinct S3 gallop. An electrocardiogram exhibits sinus tachycardia with established Q waves in leads $\text{V}_1$ through $\text{V}_4$ . Arterial blood gas analysis on room air demonstrates a $\text{pH}$ of $7.48$ , $\text{PaCO}_2$ of $30\text{ mmHg}$ , $\text{PaO}_2$ of $55\text{ mmHg}$ , and $\text{HCO}_3^-$ of $22\text{ mEq/L}$ . Which of the following represents the most appropriate initial pharmacological approach to address this patient's acute symptoms?

Administration of nebulized short-acting beta-agonists and systemic glucocorticoids

Intravenous administration of sodium bicarbonate

Intravenous administration of a loop diuretic and a vasodilator

Intravenous administration of a broad-spectrum cephalosporin and a macrolide

Administration of nebulized anticholinergic agents and targeted low-flow oxygen therapy

Show answer & explanation

Answer: Intravenous administration of a loop diuretic and a vasodilator

Answer

Intravenous administration of a loop diuretic and a vasodilator

The correct approach addresses the patient's acute decompensated heart failure (ADHF) presenting as pulmonary edema. Despite the prominent, diffuse wheezing, the patient's history of ischemic heart disease, new-onset orthopnea, expectoration of frothy pink sputum, and the presence of an S3 gallop confirm a cardiogenic etiology, often referred to clinically as 'cardiac asthma'. The severe hypertension (

185/105\text{ mmHg}

) indicates a significantly increased afterload that is contributing to left ventricular failure. The most appropriate initial pharmacological strategy involves simultaneous preload and afterload reduction using an intravenous loop diuretic (e.g., furosemide) and a rapid-acting vasodilator (e.g., nitroglycerin), alongside supplemental oxygen.

Step-by-Step Solution

Analyze the patient's presenting symptoms and vital signs.

The patient is experiencing acute, severe respiratory distress with profound hypoxia (

86\%

on room air), significant hypertension (

185/105\text{ mmHg}

), and prominent wheezing.

Establishing the severity and acuity of the presentation is necessary to prioritize initial life-saving interventions.

Evaluate the patient's medical history and specific physical examination findings.

The history of ischemic heart disease, orthopnea, expectoration of frothy pink sputum, and an S3 gallop strongly point to a cardiogenic etiology.

Differentiating between pulmonary and cardiovascular causes of acute wheezing ('cardiac asthma' vs. primary asthma/COPD) requires synthesizing specific historical clues and cardiac signs.

Interpret the objective diagnostic data.

The electrocardiogram shows established anterior ischemic changes. The arterial blood gas indicates a primary respiratory alkalosis (

\text{pH } 7.48

, low

\text{PaCO}_2

) driven by hypoxia, ruling out the acute hypercapnic respiratory acidosis commonly seen in severe COPD exacerbations.

Objective data confirms the diagnosis of acute cardiogenic pulmonary edema and excludes mixed or alternative metabolic derangements.

Determine the most appropriate pharmacological management.

Given the cardiogenic origin (acute decompensated heart failure) coupled with severe hypertension, aggressive preload and afterload reduction are required.

Loop diuretics remove excess intravascular fluid volume, and vasodilators rapidly lower blood pressure, effectively relieving pulmonary congestion.

Key Concept

Cardiac asthma is a presentation of acute decompensated heart failure that can mimic primary pulmonary disease due to peribronchial edema causing severe wheezing; management strictly requires diuretics and vasodilators rather than standard bronchodilator therapy.

Estimated Time:1m 30s

Question 430Question →

Match each clinical condition or syndrome with its classic electrocardiographic (ECG) finding.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Brugada syndrome matches with pseudo-right bundle branch block and coved ST elevation in V1-V3. Wellens syndrome matches with deeply inverted or biphasic T waves in V2-V3 during a pain-free interval. Wolff-Parkinson-White pattern matches with a short PR interval, widened QRS, and a slurred initial QRS upstroke. Acute pericarditis matches with widespread concave ST-segment elevation and reciprocal PR-segment depression.

Each syndrome has a highly distinct, pathognomonic ECG signature. Brugada syndrome involves sodium channel dysfunction leading to right precordial ST changes. Wellens syndrome reflects reperfusion of a critical LAD occlusion. WPW is caused by pre-excitation via the bundle of Kent. Acute pericarditis produces diffuse inflammatory electrical changes.

Step-by-Step Solution

Analyze the right precordial lead changes (V1-V3) associated with channelopathies.

Brugada syndrome matches with pseudo-right bundle branch block and coved ST elevation in V1-V3.

These are the hallmark Brugada type 1 ECG findings that predispose patients to sudden cardiac death.

Evaluate the anterior lead changes occurring during pain-free intervals in acute coronary syndromes.

Wellens syndrome matches with deeply inverted or biphasic T waves in V2-V3.

This specific pattern represents a highly specific marker for critical proximal left anterior descending artery stenosis.

Identify the ECG manifestations of an atrioventricular accessory pathway.

Wolff-Parkinson-White pattern matches with a short PR interval, widened QRS, and slurred initial QRS upstroke.

The accessory pathway (bundle of Kent) bypasses the AV node, causing early ventricular depolarization visible as a delta wave.

Determine the electrocardiographic hallmark of generalized epicardial inflammation.

Acute pericarditis matches with widespread concave ST-segment elevation and PR-segment depression.

Diffuse inflammation affects multiple coronary territories simultaneously, which is distinct from localized ischemia.

Key Concept

Recognition of classic high-yield electrocardiographic syndromes and their specific morphologic findings.

Question 431Question →

A 62-year-old man with a history of advanced non-small cell lung cancer is brought to the emergency department due to progressive shortness of breath and lightheadedness over the past three days. Today, he had a syncopal episode. His temperature is $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure is $78/48\text{ mmHg}$ , pulse is $122/\text{min}$ , and respiratory rate is $24/\text{min}$ . Pulsus paradoxus is $18\text{ mmHg}$ . Physical examination reveals distended jugular veins and distant, muffled heart sounds. Lungs are clear to auscultation bilaterally. An electrocardiogram shows sinus tachycardia with low QRS voltage and electrical alternans.

Arrange the following management steps in the most appropriate chronological sequence for this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct management sequence for this patient with acute cardiac tamponade is to first confirm the diagnosis with a bedside echocardiogram, temporize hemodynamics with an intravenous fluid bolus, definitively treat the shock with pericardiocentesis, send the fluid for diagnostic analysis, and finally consult surgery for a pericardial window to prevent recurrence.

This patient presents with Beck's triad (hypotension, distended neck veins, muffled heart sounds), pulsus paradoxus, and electrical alternans, which are classic signs of cardiac tamponade. Given his history of lung cancer, this is likely secondary to a malignant pericardial effusion. The sequential management of this life-threatening emergency must follow a strict algorithm. The immediate first step is to perform a bedside transthoracic echocardiogram to confirm the diagnosis and visualize the effusion. Once confirmed, administering a rapid intravenous normal saline bolus temporizes the patient by increasing right ventricular preload to forcibly overcome the restrictive pericardial pressure. Following this stabilization bridge, emergent ultrasound-guided pericardiocentesis must be performed to physically evacuate the fluid and restore cardiac output. After acute stabilization is achieved and the fluid is removed, the drained sample is submitted for cytological and microbiological analysis to firmly establish the malignant etiology. Finally, because malignant effusions have an exceptionally high recurrence rate, a surgical consultation for a subxiphoid pericardial window is indicated as the final step for long-term management.

Step-by-Step Solution

Confirm the diagnosis

Bedside transthoracic echocardiogram reveals a large pericardial effusion with right ventricular diastolic collapse.

Although clinical signs strongly suggest tamponade, imaging is required to confirm the diagnosis and safely guide subsequent invasive interventions.

Temporize hemodynamics

An intravenous normal saline bolus increases right-sided filling pressures.

Intravascular volume expansion helps the right ventricle overcome the elevated intrapericardial pressure, acting as a vital bridge to keep the patient alive while setting up for drainage.

Relieve pericardial pressure

Emergent ultrasound-guided pericardiocentesis drains the effusion, resolving the shock.

Evacuation of the fluid is the definitive acute, life-saving intervention for cardiac tamponade that immediately restores cardiac output.

Diagnose the underlying etiology

Pericardial fluid is sent for cytology and microbiology.

Identifying the cause (e.g., identifying malignant cells due to his history of lung cancer) is necessary to dictate long-term, disease-specific management.

Prevent future recurrence

Surgical consultation is obtained for a pericardial window.

Malignant effusions frequently and rapidly reaccumulate; a pericardial window provides a permanent drainage route into the pleural or peritoneal space.

Key Concept

The management sequence of acute cardiac tamponade relies on rapid echocardiographic confirmation, hemodynamic temporization with IV fluids, immediate pericardiocentesis, followed by diagnostic fluid analysis and definitive surgical interventions to prevent recurrence in malignant cases.

Question 432Question →

A $28$ -year-old man is brought to the emergency department by his roommate due to confusion, severe shortness of breath, and inability to lie flat. The roommate reports that the patient had a fever, myalgias, and a sore throat a week ago that had seemingly resolved. The patient's temperature is $37.1^\circ C$ ( $98.8^\circ F$ ), heart rate is $134$ /min, blood pressure is $82/55$ mm Hg, and respiratory rate is $28$ /min. Pulse oximetry shows $88\%$ on room air. On physical examination, the patient is lethargic and his extremities are cool and mottled. The jugular venous pressure is elevated at $11$ cm $H_2O$ . Lung auscultation reveals bibasilar crackles extending midway up the lung fields, along with scattered expiratory wheezes. Cardiac auscultation reveals tachycardia, a regular rhythm, and a distinct third heart sound (S3).

Laboratory results are as follows:
Leukocyte count: $8,500/mm^3$
Lactic acid: $4.5$ $mmol/L$
Troponin I: $1.2$ $ng/mL$ (normal $< 0.04$ )
Thyroid-stimulating hormone (TSH): $0.2$ $\mu U/mL$ (normal $0.4-4.0$ )
Free T4: $0.7$ $ng/dL$ (normal $0.9-1.7$ )

An electrocardiogram shows sinus tachycardia with diffuse non-specific ST-segment and T-wave abnormalities. Which of the following is the most appropriate next step in management?

Perform bedside transthoracic echocardiography

Administer intravenous furosemide and inhaled albuterol

Transport to radiology for computed tomography angiography of the chest

Administer intravenous ceftriaxone and azithromycin

Initiate oral levothyroxine therapy

Show answer & explanation

Answer: Perform bedside transthoracic echocardiography

Answer

Perform bedside transthoracic echocardiography

The correct answer is to perform bedside transthoracic echocardiography. This patient is presenting with acute cardiogenic shock, evidenced by severe hypotension (

82/55

mm Hg), poor tissue perfusion (lethargy, cool and mottled extremities, elevated lactic acid), and biventricular failure (elevated JVP, bibasilar crackles, S3 gallop). The recent history of fever, myalgias, and sore throat followed by sudden cardiac decompensation with an elevated troponin is classic for acute viral myocarditis. In any hemodynamically unstable patient, diagnostic testing must be performed at the bedside. Transthoracic echocardiography is the modality of choice as it will rapidly confirm severely depressed left ventricular systolic function and rule out other potential causes of obstructive or cardiogenic shock (such as a large pericardial effusion leading to tamponade) before initiating definitive therapy like inotropic support (e.g., dobutamine).

Step-by-Step Solution

Analyze the patient's hemodynamic status and clinical signs.

The patient is in shock (blood pressure

82/55

mm Hg, lethargy, cool/mottled extremities, lactic acidosis

4.5

mmol/L

) with signs of heart failure (JVP

11

H_2O

, pulmonary crackles, S3 gallop).

Identifying the type of shock is critical. The combination of hypotension and elevated filling pressures (JVP, pulmonary edema) definitively points to cardiogenic shock.

Correlate the shock state with the history and laboratory findings.

A recent viral prodrome followed by acute decompensated heart failure and elevated troponin in a young, previously healthy patient suggests acute viral myocarditis.

Viral myocarditis is a classic cause of sudden-onset dilated cardiomyopathy and cardiogenic shock in young adults.

Determine the safest and most diagnostic next step for an unstable patient in cardiogenic shock.

Bedside transthoracic echocardiography is selected.

An unstable patient must not leave the resuscitation area. Bedside echocardiography rapidly assesses left ventricular ejection fraction, evaluates regional wall motion, and rules out other catastrophic causes like cardiac tamponade, guiding the safe initiation of inotropic support.

Key Concept

In patients presenting with suspected cardiogenic shock (hypotension, elevated JVP, pulmonary edema), immediate bedside transthoracic echocardiography is the diagnostic test of choice to evaluate cardiac function and structure without endangering the unstable patient through transport.

Estimated Time:1m 30s

Question 433Question →

A $70$ -year-old man with a history of chronic obstructive pulmonary disease (COPD) and hypertension is brought to the emergency department by ambulance due to the sudden onset of severe substernal chest pressure, shortness of breath, and diaphoresis that began $45\text{ minutes}$ ago. Upon arrival, his blood pressure is $85/54\text{ mmHg}$ , heart rate is $108\text{/min}$ , and respiratory rate is $22\text{/min}$ . Pulse oximetry is $94\%$ on room air. Physical examination reveals elevated jugular venous pressure with prominent $x$ and $y$ descents. Lung auscultation is clear bilaterally with mildly prolonged expiration but no wheezes or crackles. A $12$ -lead electrocardiogram demonstrates $3\text{ mm}$ ST-segment elevations in leads II, III, and aVF, with reciprocal ST-segment depressions in leads I and aVL.

In addition to preparation for emergent percutaneous coronary intervention, what is the most appropriate initial step in the management of this patient?

Intravenous furosemide

Sublingual nitroglycerin

Intravenous normal saline bolus

Inhaled albuterol and systemic corticosteroids

Noninvasive positive pressure ventilation

Show answer & explanation

Answer: Intravenous normal saline bolus

Answer

Intravenous normal saline bolus

The correct answer is an intravenous normal saline bolus. This patient's electrocardiogram shows an acute inferior wall myocardial infarction (ST elevations in leads II, III, and aVF). The accompanying clinical triad of hypotension, elevated jugular venous pressure, and clear lung fields strongly suggests a right ventricular (RV) infarction, which complicates up to 50% of inferior myocardial infarctions. The ischemic right ventricle has significantly impaired contractility and becomes highly dependent on elevated preload to maintain forward flow through the pulmonary circulation to the left ventricle. Therefore, the most appropriate initial management for hypotension in the setting of an RV infarction is volume expansion with intravenous isotonic fluids (e.g., normal saline) to maximize the Starling mechanism and improve cardiac output.

Step-by-Step Solution

Analyze the patient's clinical presentation and electrocardiogram (ECG) findings.

The patient exhibits hypotension, elevated jugular venous pressure, clear lung fields, and ST-segment elevations in inferior leads (II, III, and aVF).

Identifying the classic clinical triad combined with inferior ECG changes is essential to diagnose an acute right ventricular (RV) myocardial infarction.

Determine the pathophysiologic state of the right ventricle in this condition.

The ischemic right ventricle loses its contractility and becomes highly dependent on elevated right-sided filling pressures (preload).

Understanding RV preload dependence is crucial for selecting the correct hemodynamic intervention and avoiding fatal medication errors.

Select the appropriate initial management for the patient's hypotension.

Intravenous fluid resuscitation (e.g., normal saline) is indicated.

Increasing preload maximizes the Starling mechanism, thereby maintaining forward blood flow through the pulmonary circulation to the left ventricle and improving systemic blood pressure.

Key Concept

Right ventricular myocardial infarction presents with the triad of hypotension, elevated jugular venous pressure, and clear lungs. It is a highly preload-dependent state that requires intravenous fluid resuscitation; preload-reducing therapies must be strictly avoided.

Estimated Time:1m 15s

Question 434Question →

A 70-year-old woman is brought to the emergency department by ambulance due to the abrupt onset of severe shortness of breath that began 45 minutes ago while she was watching television. She has a history of severe chronic obstructive pulmonary disease (COPD), hypertension, and a myocardial infarction 3 years ago. She appears extremely anxious, diaphoretic, and is speaking in one-word sentences. Vital signs are temperature $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure $225/115\text{ mmHg}$ , pulse $118\text{/min}$ , and respirations $32\text{/min}$ . Oxygen saturation is $85\%$ on room air.

Physical examination shows prominent use of accessory muscles of respiration. Lung auscultation reveals diffuse high-pitched expiratory wheezing bilaterally and bibasilar crackles. Cardiac auscultation reveals an $S_4$ gallop. There is no jugular venous distension or peripheral edema.

Arterial blood gas on room air reveals:
- pH: $7.25$
- $\text{pCO}_2$ : $65\text{ mmHg}$
- $\text{pO}_2$ : $50\text{ mmHg}$
- $\text{HCO}_3^-$ : $28\text{ mEq/L}$

Which of the following is the most appropriate initial management for this patient?

Noninvasive positive-pressure ventilation and intravenous nitroglycerin

Nebulized ipratropium-albuterol and intravenous methylprednisolone

Intravenous furosemide and supplemental oxygen via nasal cannula

Intravenous levofloxacin and intravenous methylprednisolone

Intravenous sodium bicarbonate and endotracheal intubation

Show answer & explanation

Answer: Noninvasive positive-pressure ventilation and intravenous nitroglycerin

Answer

Noninvasive positive-pressure ventilation and intravenous nitroglycerin

This patient is presenting with Sympathetic Crashing Acute Pulmonary Edema (SCAPE), a severe phenotype of acute decompensated heart failure. SCAPE is characterized by the abrupt onset (minutes to hours) of extreme dyspnea, flash pulmonary edema, and severe hypertension resulting from a sympathetic surge and massive afterload increase. Unlike classic heart failure exacerbations, these patients are often euvolemic (no peripheral edema or JVD) but suffer from rapid fluid redistribution from the systemic circulation into the pulmonary vasculature. The prominent wheezing ('cardiac asthma') and history of COPD can mislead clinicians into diagnosing a COPD exacerbation. However, the extreme hypertension, acute onset, and

S_4

gallop strongly point to a cardiac etiology. The most appropriate initial management is rapid afterload reduction with high-dose intravenous nitroglycerin and noninvasive positive-pressure ventilation (NIPPV). NIPPV decreases left ventricular transmural pressure (reducing afterload), decreases venous return (reducing preload), and directly treats hypoxemia and the work of breathing.

Step-by-Step Solution

Analyze the clinical presentation and temporal onset.

The patient has abrupt onset (45 minutes) of severe dyspnea, extreme hypertension (225/115 mmHg), and flash pulmonary edema without peripheral edema.

Differentiates Sympathetic Crashing Acute Pulmonary Edema (SCAPE) from a typical gradual COPD exacerbation or volume-overload heart failure.

Interpret the physical exam findings.

Wheezing with bibasilar crackles and an S4 gallop indicates 'cardiac asthma' secondary to acute elevated left ventricular end-diastolic pressure, not isolated bronchospasm.

Identifies the cardiac etiology of the respiratory distress despite the history of COPD.

Evaluate the arterial blood gas results.

pH 7.25 and pCO2 65 mmHg indicate acute respiratory acidosis with severe hypoxemia.

Confirms the need for immediate ventilatory support.

Determine the most appropriate initial interventions.

Select interventions that rapidly decrease afterload and support ventilation without intubation if possible.

Intravenous nitroglycerin causes rapid vasodilation (reducing afterload and preload), while NIPPV improves oxygenation and decreases work of breathing.

Key Concept

Management of Sympathetic Crashing Acute Pulmonary Edema (SCAPE)

Estimated Time:1m 30s

Question 435Question →

A 58-year-old man suddenly collapses while walking in the hospital hallway. He is unresponsive, apneic, and has no palpable carotid pulse. The emergency response team arrives immediately with a resuscitation cart. The cardiac monitor displays coarse ventricular fibrillation. According to the Advanced Cardiovascular Life Support (ACLS) guidelines, arrange the following management steps in the correct chronological order for this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Initiate high-quality chest compressions, 2) Deliver the first unsynchronized shock, 3) Immediately resume chest compressions and obtain IV access, 4) Deliver a second shock and administer epinephrine, and 5) Deliver a third shock and administer amiodarone.

The Advanced Cardiovascular Life Support (ACLS) algorithm for shockable rhythms (ventricular fibrillation or pulseless ventricular tachycardia) dictates starting with high-quality CPR. As soon as the defibrillator is ready, the first unsynchronized shock is delivered. CPR is then immediately resumed for 2 minutes while intravenous or intraosseous access is obtained; no rhythm check should occur immediately after the shock. If the rhythm remains shockable at the next check, a second shock is delivered, CPR is resumed, and epinephrine (1 mg) is administered. If the rhythm is still shockable after another 2 minutes of CPR, a third shock is delivered, CPR is resumed, and an antiarrhythmic like amiodarone (300 mg) is administered.

Step-by-Step Solution

Identify cardiac arrest and begin basic life support.

Chest compressions provide temporary circulation.

Immediate CPR is critical for survival and neurological outcome by maintaining minimal organ perfusion.

Analyze the rhythm and deliver the first shock for ventricular fibrillation.

Attempts to depolarize the myocardium to allow the sinus node to reset.

Early defibrillation is the definitive treatment for pulseless ventricular tachycardia and ventricular fibrillation.

Immediately resume CPR and establish vascular access.

Maintains perfusion without delaying compressions.

Prolonged pauses in chest compressions (such as checking for a rhythm immediately after a shock) decrease the chance of successful defibrillation and survival.

Deliver a second shock if VF persists, resume CPR, and give epinephrine.

Epinephrine provides vasopressor support during continued arrest.

Alpha-adrenergic effects of epinephrine cause peripheral vasoconstriction, increasing aortic diastolic pressure and improving coronary perfusion pressure.

Deliver a third shock if VF persists, resume CPR, and give amiodarone.

Antiarrhythmic therapy for shock-refractory VF.

Amiodarone affects sodium, potassium, and calcium channels and has been shown to improve the rates of return of spontaneous circulation (ROSC) in shock-refractory VF.

Key Concept

Advanced Cardiovascular Life Support (ACLS) Pulseless Arrest Algorithm for Shockable Rhythms

Estimated Time:1m 30s

Question 436Question →

A $69$ -year-old man is brought to the emergency department by his family due to rapidly worsening shortness of breath over the past $24$ hours. He has a history of hypertension, coronary artery disease, and a $45$ -pack-year smoking history. Two weeks ago, he was evaluated at an urgent care clinic for a mild productive cough; a sputum culture at that time grew *Streptococcus pneumoniae* that was highly susceptible to penicillin.

Currently, he is sitting upright and is unable to speak in full sentences. His temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $168/94$ mm Hg, pulse is $112$ /min, and respirations are $28$ /min. Oxygen saturation is $88\%$ on room air.

Physical examination reveals a patient in marked respiratory distress. The jugular venous pressure is elevated at $10$ cm H $_2$ O. Chest auscultation reveals diffuse wheezing and bilateral fine crackles in the lower two-thirds of both lung fields. Cardiac examination shows tachycardia and a regular rhythm, with an extra, low-frequency sound heard just after S2 at the cardiac apex. The lower extremities show $2+$ bilateral pitting edema.

Laboratory studies are as follows:
Leukocyte count: $8,200/\text{mm}^3$
Hemoglobin: $13.4$ g/dL
Serum creatinine: $1.3$ mg/dL
Thyroid-stimulating hormone (TSH): $0.9$ mU/L (Normal: $0.5$ – $5.0$ mU/L)
Free thyroxine (T4): $0.7$ ng/dL (Normal: $0.9$ – $1.7$ ng/dL)

Which of the following is the most appropriate initial step in the pharmacologic management of this patient?

Intravenous administration of torsemide

Inhaled administration of short-acting beta-agonists

Intravenous administration of methylprednisolone

Intravenous administration of broad-spectrum levofloxacin

Initiation of oral levothyroxine therapy

Show answer & explanation

Answer: Intravenous administration of torsemide

Answer

Intravenous administration of torsemide

The correct answer provides a rapid mechanism to reduce intravascular volume and left ventricular preload. This patient's clinical picture—elevated jugular venous pressure, bibasilar crackles, an S3 gallop (an extra low-frequency sound after S2), and lower extremity edema—is pathognomonic for acute decompensated heart failure (ADHF). The diffuse wheezing is a manifestation of 'cardiac asthma,' which occurs when pulmonary venous hypertension leads to peribronchial edema and subsequent bronchospasm. The immediate administration of an intravenous loop diuretic (e.g., torsemide, furosemide, or bumetanide) is the mainstay of initial therapy for ADHF to alleviate pulmonary congestion.

Step-by-Step Solution

Analyze the patient's presentation and physical examination findings.

The patient has severe dyspnea, hypoxemia, elevated jugular venous pressure, an S3 gallop, bibasilar crackles, and bilateral pitting edema.

These findings are classic for acute left and right ventricular volume overload (Acute Decompensated Heart Failure).

Differentiate the cause of wheezing in this clinical context.

The wheezing is identified as 'cardiac asthma'—bronchospasm caused by peribronchial edema from left heart failure—rather than a primary COPD exacerbation.

The presence of an S3 gallop and elevated JVP strongly points to a cardiac etiology rather than primary pulmonary disease.

Interpret the laboratory findings.

White blood cell count is normal (ruling out acute infection). TSH is normal with a mildly low T4, representing euthyroid sick syndrome.

This rules out concurrent pneumonia or primary hypothyroidism as the driver of his decompensation.

Determine the most appropriate initial management.

Rapid preload reduction is required.

Intravenous loop diuretics (such as torsemide or bumetanide) rapidly decrease circulating volume and relieve pulmonary congestion.

Key Concept

The classic presentation of acute decompensated heart failure includes volume overload signs (elevated JVP, S3 gallop, crackles, edema) and should be initially managed with intravenous loop diuretics, even when wheezing ('cardiac asthma') is present.

Alternative Method

In cases of severe acute decompensated heart failure with hypoxemia that does not respond immediately to supplemental oxygen and diuretics, non-invasive positive pressure ventilation (NIPPV) is an important adjunct to reduce work of breathing and improve oxygenation.

Estimated Time:1m 30s

Question 437Question →

Match each specific cardiovascular pathology with its most characteristic arterial pulse or hemodynamic physical examination finding.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Chronic severe aortic regurgitation matches with rapidly rising bounding pulse; Hypertrophic obstructive cardiomyopathy matches with bifid carotid pulse; Cardiac tamponade matches with exaggerated decrease in systolic blood pressure during inspiration; Severe calcific aortic stenosis matches with diminished and delayed carotid upstroke.

Each cardiovascular pathology produces distinct hemodynamic alterations that manifest as specific physical examination findings. Aortic regurgitation causes a widened pulse pressure and bounding pulse due to rapid forward and backward flow. Hypertrophic obstructive cardiomyopathy creates a bifid pulse due to dynamic outflow obstruction. Cardiac tamponade exaggerates ventricular interdependence, leading to pulsus paradoxus. Severe aortic stenosis creates a fixed outflow obstruction, resulting in a weak and delayed pulse.

Step-by-Step Solution

Analyze the hemodynamics of chronic severe aortic regurgitation.

Identify that rapid forward flow and backward regurgitation create a rapidly rising bounding pulse with a quick collapse.

This corresponds to the classic water-hammer or Corrigan pulse.

Analyze the hemodynamics of hypertrophic obstructive cardiomyopathy.

Identify that dynamic outflow tract obstruction causes a bifid carotid pulse with a brisk initial upstroke followed by a mid-systolic dip.

This corresponds to the classic pulsus bisferiens.

Analyze the hemodynamics of cardiac tamponade.

Identify that fixed pericardial space constraints lead to an exaggerated decrease in systolic blood pressure during inspiration (> 10 mm Hg).

This corresponds to pulsus paradoxus.

Analyze the hemodynamics of severe calcific aortic stenosis.

Identify that a fixed mechanical obstruction limits and delays forward flow, resulting in a diminished amplitude and delayed peak of the carotid upstroke.

This corresponds to pulsus parvus et tardus.

Key Concept

Physical examination correlates of cardiovascular hemodynamics and structural heart disease.

Question 438Question →

A $65$ -year-old man comes to the clinic with a $3$ -month history of progressive exertional dyspnea, lower extremity swelling, and abdominal fullness. He has a $30$ -pack-year smoking history and mild chronic obstructive pulmonary disease. Twenty years ago, he was diagnosed with Hodgkin lymphoma and treated with chemotherapy and mantle field radiation.

Vital signs show a blood pressure of $115/75$ mm Hg, pulse of $92$ /min, and respirations of $18$ /min. Pulse oximetry is $96\%$ on room air.

Physical examination reveals an elevated jugular venous pulsation at $11$ cm H $_2$ O that paradoxically increases during inspiration. Auscultation of the heart reveals a regular rhythm and a high-frequency sound just after S $_2$ . The lungs are clear to auscultation bilaterally. The abdomen is distended with shifting dullness, and there is 2+ bilateral pitting edema to the knees.

Laboratory results are as follows:
Thyroid-stimulating hormone (TSH): $2.1$ $\mu$ U/mL (Normal: $0.4$ - $4.0$ $\mu$ U/mL)
Free T $_4$ : $1.0$ ng/dL (Normal: $0.9$ - $2.4$ ng/dL)
Total T $_3$ : $60$ ng/dL (Normal: $80$ - $200$ ng/dL)

Which of the following is the most likely primary pathophysiologic mechanism responsible for this patient's current presentation?

Restricted diastolic filling of the ventricles due to a rigid pericardium

Pulmonary arterial vasoconstriction secondary to chronic alveolar hypoxia

Left ventricular systolic dysfunction resulting in elevated pulmonary capillary wedge pressure

Decreased myocardial contractility secondary to impaired pituitary hormone production

Exaggerated drop in intrathoracic pressure during inspiration leading to decreased left ventricular stroke volume

Show answer & explanation

Answer: Restricted diastolic filling of the ventricles due to a rigid pericardium

Answer

Restricted diastolic filling of the ventricles due to a rigid pericardium

This patient's clinical presentation is highly characteristic of constrictive pericarditis, a known late complication of mediastinal radiation therapy (often used for Hodgkin lymphoma). The radiation causes chronic inflammation, leading to a thickened, fibrotic, and rigid pericardial sac. This rigid pericardium restricts the diastolic filling of the ventricles, causing blood to back up into the systemic venous system, which manifests as right-sided heart failure (elevated jugular venous pressure, hepatomegaly, ascites, and peripheral edema). Classic physical examination findings include Kussmaul sign (a paradoxical increase in jugular venous pressure during inspiration, as the right ventricle cannot accommodate the increased venous return) and a pericardial knock (a high-frequency early diastolic sound caused by the sudden cessation of ventricular filling). The patient's clear lungs indicate the absence of left heart volume overload.

Step-by-Step Solution

Analyze the patient's presenting symptoms and physical examination findings.

The patient has signs of right-sided heart failure (elevated jugular venous pressure, ascites, bilateral pitting edema) without signs of left-sided heart failure (clear lungs). He also has a Kussmaul sign (inspiratory increase in jugular venous pressure) and a pericardial knock (high-frequency early diastolic sound).

Identifying the pattern of isolated right heart failure with specific physical exam signs helps narrow the differential diagnosis.

Correlate the physical findings with the patient's past medical history.

The patient had mantle field radiation for Hodgkin lymphoma

20

years ago. This history, combined with Kussmaul sign and a pericardial knock, strongly suggests constrictive pericarditis.

Radiation therapy is a major risk factor for the development of constrictive pericarditis, which can occur years or decades after exposure.

Evaluate the laboratory findings to rule out confounding conditions.

The thyroid panel shows a low total T

_3

but normal TSH and free T

_4

, which is diagnostic of euthyroid sick syndrome (common in chronic heart failure), ruling out a primary or secondary thyroid disorder as the cause of his symptoms.

It is important to ensure that the symptoms are not driven by a correctable metabolic abnormality.

Determine the pathophysiologic mechanism of the confirmed diagnosis.

Constrictive pericarditis is characterized by a scarred, rigid pericardium that restricts the diastolic filling of the ventricles, leading to systemic venous congestion.

This directly answers the question regarding the underlying mechanism of the patient's presentation.

Key Concept

Constrictive Pericarditis

Question 439Question →

A 64-year-old man is brought to the emergency department complaining of sudden-onset, severe, tearing chest pain that radiates to his interscapular region. His blood pressure is 185/110 mmHg in the right arm and 145/85 mmHg in the left arm. His heart rate is 112/min. A portable chest radiograph reveals a widened mediastinum. Acute aortic dissection is highly suspected. Arrange the following steps in the most appropriate sequential order for the acute management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of management is: 1) Initiate intravenous esmolol infusion, 2) Initiate intravenous sodium nitroprusside infusion, 3) Obtain contrast-enhanced CT angiography of the chest, 4) Consult cardiothoracic surgery for definitive management.

The precise sequence for managing suspected acute aortic dissection is crucial for patient survival. The immediate goal is 'anti-impulse' therapy to reduce aortic wall shear stress. This begins with intravenous beta-blockers (e.g., esmolol) to decrease heart rate and left ventricular contractility (dP/dt). Once the heart rate is controlled, if the systolic blood pressure remains >120 mmHg, an intravenous vasodilator (e.g., sodium nitroprusside) is added. After hemodynamic stabilization, definitive imaging (CT angiography or TEE) is performed to classify the dissection, followed by surgical consultation, as Type A dissections require emergency repair.

Step-by-Step Solution

Recognize the clinical presentation and prioritize stabilization.

The patient's tearing chest pain, asymmetric blood pressures, and widened mediastinum strongly suggest an acute aortic dissection. Immediate hemodynamic stabilization is required.

Acute aortic dissection is a life-threatening emergency where ongoing shear stress on the aortic wall can lead to fatal rupture or propagation.

Determine the critical first pharmacological intervention.

Intravenous beta-blockers (e.g., esmolol or labetalol) must be administered first.

Beta-blockers reduce heart rate (target < 60/min) and decrease left ventricular contractility (dP/dt), which is the primary driver of aortic wall shear stress.

Determine the subsequent step for blood pressure control.

Intravenous vasodilators (e.g., sodium nitroprusside) are added only after adequate beta-blockade is achieved.

Vasodilators lower systolic blood pressure to the target of 100-120 mmHg. They must be given after beta-blockers to prevent reflex tachycardia and a subsequent increase in dP/dt.

Identify the next diagnostic step.

Definitive imaging with CT angiography is performed.

Once anti-impulse therapy has stabilized the hemodynamics, imaging is required to confirm the diagnosis and determine the anatomical extent (ascending vs. descending aorta).

Determine the final management step.

Consult cardiothoracic surgery.

Surgical evaluation is necessary for definitive treatment, as ascending (Type A) dissections require emergency surgical repair, while descending (Type B) dissections are typically managed medically unless complicated.

Key Concept

In the initial management of acute aortic dissection, beta-blockers (to reduce dP/dt and heart rate) MUST be administered before vasodilators (to lower blood pressure) to prevent reflex tachycardia and worsening of the dissection.

Question 440Question →

A $68$ -year-old woman is evaluated on postoperative day $3$ following an elective open sigmoid colectomy for recurrent diverticulitis. Over the past $2$ hours, she has developed significant shortness of breath, diaphoresis, and acute confusion. Her medical history is significant for hypertension, type $2$ diabetes mellitus, chronic obstructive pulmonary disease, and major depressive disorder. Her home medications, which were restarted postoperatively, include lisinopril, metformin, tiotropium, and citalopram. Temperature is $37.9^\circ$ C ( $100.2^\circ$ F), blood pressure is $82/50$ mm Hg, pulse is $122$ /min, and respirations are $28$ /min. Pulse oximetry shows $88\%$ on room air. Physical examination reveals elevated jugular venous pressure and a new, harsh, holosystolic murmur heard best at the cardiac apex with radiation to the axilla. Lung auscultation demonstrates bilateral crackles extending up to the mid-lung fields. The abdomen is soft, mildly distended, and tender near the surgical incision, which is clean and intact. An electrocardiogram reveals sinus tachycardia with $2$ -mm ST-segment depressions in leads II, III, and aVF. Which of the following is the most appropriate next step in management?

Administer inhaled albuterol and intravenous methylprednisolone

Perform immediate bedside echocardiography

Transport the patient for a computed tomography scan of the abdomen

Obtain blood cultures and initiate intravenous broad-spectrum antibiotics

Administer intravenous haloperidol to manage acute delirium

Show answer & explanation

Answer: Perform immediate bedside echocardiography

Answer

The most appropriate next step is to perform an immediate bedside echocardiography to assess for acute mitral regurgitation secondary to a perioperative myocardial infarction.

The correct action is performing a bedside echocardiogram. This patient has classic signs of acute mitral regurgitation (new holosystolic apical murmur, sudden pulmonary edema, cardiogenic shock) occurring in the setting of inferior myocardial ischemia (ST depressions in II, III, and aVF). The posteromedial papillary muscle of the mitral valve has a fragile, single blood supply from the posterior descending artery, making it highly vulnerable to ischemic dysfunction or rupture. Bedside echocardiography rapidly visualizes the valve structures and confirms the diagnosis without requiring the transport of a hemodynamically unstable patient.

Step-by-Step Solution

Identify the primary physiologic derangement.

The patient is experiencing cardiogenic shock (hypotension, tachycardia, altered mental status) accompanied by acute pulmonary edema (hypoxia, bilateral crackles).

Recognizing the shock phenotype narrows the differential diagnosis away from simple postoperative respiratory issues.

Correlate the physical examination with the electrocardiogram findings.

A new holosystolic apical murmur radiating to the axilla indicates acute mitral regurgitation. The ECG shows ischemic changes in the inferior leads (II, III, aVF).

The posteromedial papillary muscle is supplied solely by the posterior descending artery (PDA). Inferior wall ischemia frequently leads to dysfunction or rupture of this muscle, causing severe, acute mitral regurgitation.

Select the safest, most rapid diagnostic modality.

Bedside echocardiography is selected.

In a hemodynamically unstable patient, bedside ultrasound confirms the mechanical complication quickly without the risks associated with patient transport.

Key Concept

Acute mechanical complications of perioperative myocardial infarction, specifically papillary muscle dysfunction leading to acute mitral regurgitation and cardiogenic shock.

Estimated Time:1m 15s

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