MD Cardiovascular System Pathophysiology 2

Question 1

A 65-year-old man with hypertension develops left ventricular hypertrophy. Which hemodynamic change most directly drives this adaptation?

Accepted Answer

Increased afterload due to elevated systemic vascular resistance

Answer

Chronic pressure overload from elevated afterload (e.g., systemic hypertension) stimulates concentric left ventricular hypertrophy.

Question 2

During myocardial ischemia, anaerobic metabolism leads to intracellular acidosis. What is the primary consequence of this acidosis on cardiac function?

Accepted Answer

Inhibition of phosphofructokinase reducing glycolytic ATP

Answer

Intracellular acidosis inhibits phosphofructokinase, a key glycolytic enzyme, further limiting ATP production during ischemia.

Question 3

A patient with mitral stenosis develops pulmonary hypertension. Which mechanism initially elevates pulmonary arterial pressure in this condition?

Accepted Answer

Passive back-transmission of elevated left atrial pressure

Answer

Mitral stenosis obstructs flow from left atrium to left ventricle, raising left atrial pressure that is passively transmitted backward to the pulmonary vasculature.

Question 4

Which ion channel abnormality is most responsible for the triggered arrhythmias seen in digoxin toxicity?

Accepted Answer

Sodium-potassium ATPase inhibition causing intracellular calcium overload

Answer

Digoxin inhibits Na⁺/K⁺-ATPase, raising intracellular Na⁺, which reduces Na⁺/Ca²⁺ exchanger activity, leading to calcium overload and delayed afterdepolarizations.

Question 5

A 72-year-old woman develops acute aortic regurgitation after bacterial endocarditis. Why does she develop acute pulmonary edema while a patient with chronic aortic regurgitation is compensated?

Accepted Answer

The unprepared left ventricle cannot accommodate the sudden volume load

Answer

In acute AR, the normal-sized left ventricle has poor compliance and cannot accommodate the sudden regurgitant volume, causing abrupt elevation in LV end-diastolic pressure and pulmonary edema.

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MD - Doctor of Medicine Practice Test

MD Cardiovascular System Pathophysiology 2