Progressive dyspnea and persistent chills over the past week prompt the hospitalization of… — USMLE Step 2 CK

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 replacementAnswer
B
Administer intravenous methylprednisolone and nebulized albuterol
C
Initiate a continuous norepinephrine infusion and delay surgical intervention until blood cultures are sterile
D
Transport to radiology for emergent computed tomography angiography of the chest
E
Insert an intra-aortic balloon pump to provide mechanical hemodynamic support

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

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