A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 71-year-old man presents to the emergency department with severe substernal chest pain. An initial EKG demonstrates ST elevation in leads V2, V3, V4, and V5 with reciprocal changes. The patient is started on aspirin and heparin and is transferred to the cardiac catheterization lab. The patient recovers over the next several days. On the floor, the patient complains of feeling very fatigued and feels too weak to ambulate even with the assistance of physical therapy. Chest radiography reveals an enlarged cardiac silhouette with signs of fluid bilaterally in the lung bases. His temperature is 98.4°F (36.9°C), blood pressure is 85/50 mmHg, pulse is 110/min, respirations are 13/min, and oxygen saturation is 97% on room air. Which of the following would be expected to be seen in this patient?
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A
Decreased systemic vascular resistanceIncorrect. SVR is INCREASED in cardiogenic shock as a compensatory mechanism (catecholamine surge to maintain BP); decreased SVR is the hallmark of distributive (septic, anaphylactic) shock.
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B
Decreased tissue oxygen extractionIncorrect. Tissue oxygen extraction is INCREASED in cardiogenic shock (peripheral tissues extract more O2 from each unit of blood due to low delivery), widening the A-VO2 difference and lowering mixed venous O2 saturation.
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C
Increased ejection fractionIncorrect. Ejection fraction is DECREASED in this patient — the anterior MI has damaged a large portion of LV myocardium, causing pump failure and cardiogenic shock.
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D
Increased pulmonary capillary wedge pressureCorrect. PCWP is elevated in cardiogenic shock from LV failure, reflecting backup of blood into the pulmonary circulation — directly explaining the bilateral pulmonary edema seen on this patient's chest x-ray.
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E
Decreased mixed venous oxygen saturationIncorrect. Decreased SvO2 is in fact EXPECTED in cardiogenic shock (low cardiac output leads to increased peripheral oxygen extraction), but the option as written describing decreased extraction is incorrect; elevated PCWP is the direct hemodynamic hallmark that explains the bilateral pulmonary edema.
↑ Tap an answer to reveal the reasoning
Answer: D. This patient had an anterior wall STEMI (ST elevation in V2–V5) and now, days later, develops fatigue, weakness, hypotension (85/50), tachycardia, and bilateral pulmonary edema with an enlarged cardiac silhouette. This is cardiogenic shock from acute heart-failure complication of MI, most likely due to extensive left ventricular myocardial damage with poor pump function.
Cardiogenic shock is characterized by:
- DECREASED cardiac output and ejection fraction (eliminating option C)
- INCREASED systemic vascular resistance (compensatory peripheral vasoconstriction) — eliminating option A
- INCREASED tissue oxygen extraction (low O2 delivery from low CO drives tissues to extract more from each unit of blood, widening A-VO2 difference) — eliminating option B
- INCREASED pulmonary capillary wedge pressure (PCWP, surrogate for LV end-diastolic pressure) reflecting impaired LV filling and backup into the pulmonary circulation, producing the pulmonary edema seen here
The Forrester / Swan-Ganz hemodynamic profile of cardiogenic shock is the classic “cold and wet” quadrant: cardiac index < 2.2 and PCWP > 18. By contrast, distributive (septic) shock shows DECREASED SVR and DECREASED PCWP with often increased CO. Hypovolemic shock has decreased PCWP. Obstructive shock (cardiac tamponade, massive PE, tension PTX) shows decreased CO and elevated CVP but variable PCWP.
**Why each option:**
**A.** SVR is INCREASED in cardiogenic shock as a compensatory mechanism (catecholamine surge to maintain BP); decreased SVR is the hallmark of distributive (septic, anaphylactic) shock.
**B.** Tissue oxygen extraction is INCREASED in cardiogenic shock (peripheral tissues extract more O2 from each unit of blood due to low delivery), widening the A-VO2 difference and lowering mixed venous O2 saturation.
**C.** Ejection fraction is DECREASED in this patient — the anterior MI has damaged a large portion of LV myocardium, causing pump failure and cardiogenic shock.
**D.** Correct. PCWP is elevated in cardiogenic shock from LV failure, reflecting backup of blood into the pulmonary circulation — directly explaining the bilateral pulmonary edema seen on this patient's chest x-ray.