A 28-year-old man is brought to the emergency department by his roommate due to confusion,… — USMLE Step 2 CK

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 echocardiographyAnswer
B
Administer intravenous furosemide and inhaled albuterol
C
Transport to radiology for computed tomography angiography of the chest
D
Administer intravenous ceftriaxone and azithromycin
E
Initiate oral levothyroxine therapy

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

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