Cardiovascular Drugs USMLE Step 1 Practice Question
A 52-year-old woman with dilated cardiomyopathy presents to the ICU with acute decompensated heart failure. Vital signs: BP 88/54 mmHg, HR 122/min, RR 24/min, SpO2 90% on 4L nasal cannula. Laboratory studies reveal BNP 920 pg/mL, creatinine 1.8 mg/dL (baseline 0.9), and lactate 2.1 mmol/L. Transthoracic echocardiography shows ejection fraction of 20% with global hypokinesis. The patient receives intravenous milrinone for inotropic support. Two hours later, her cardiac output increases from 3.2 to 4.1 L/min, but her systolic blood pressure decreases to 78 mmHg and systemic vascular resistance drops from 1400 to 800 dyne·sec·cm⁻⁵. Urine output remains adequate at 0.5 mL/kg/hr. Which of the following agents should be added to maintain adequate organ perfusion pressure while preserving the inotropic benefit of milrinone?
Answer choices
- AEsmolol, to reduce tachycardia and myocardial oxygen demand without altering systemic resistance
- BNorepinephrine, to provide alpha-adrenergic vasoconstriction and maintain perfusion pressureCorrect answer
- CDobutamine, to enhance inotropic effect and counteract milrinone-induced hypotension
- DHydralazine, to reduce afterload and optimize ventricular function in cardiomyopathy
- EDopamine at low dose, to increase renal perfusion and prevent acute kidney injury
- FVasopressin, to increase systemic vascular resistance independent of catecholamine receptors
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.