MD Cardiovascular System Pathophysiology 5

Question 1

A 70-year-old man with calcific aortic stenosis has a peak-to-peak gradient of 55 mmHg and valve area of 0.7 cm². He is asymptomatic. What is the most critical pathophysiologic event that signals the need for intervention?

Accepted Answer

Onset of any of: angina, syncope, or heart failure symptoms

Answer

The classic symptom triad of severe AS—angina, syncope, and heart failure—marks the inflection point at which survival drops sharply without valve replacement.

Question 2

Which pathophysiologic change most directly causes the elevated BNP levels in patients with decompensated heart failure?

Accepted Answer

Myocardial wall stress from increased ventricular filling pressure stretching cardiomyocytes

Answer

Elevated ventricular wall stress from high filling pressures mechanically stretches cardiomyocytes, triggering cleavage of proBNP into BNP and NT-proBNP.

Question 3

A 60-year-old with diabetes and chronic kidney disease develops accelerated atherosclerosis. Which mechanism most distinguishes uremia-associated vascular disease from traditional atherosclerosis?

Accepted Answer

Medial calcification from calcium-phosphate deposition and vascular smooth muscle transdifferentiation

Answer

Uremia promotes vascular calcification via hyperphosphatemia and FGF-23 signaling, causing vascular smooth muscle cells to transdifferentiate into osteoblast-like cells depositing calcium in the media.

Question 4

A patient develops cardiac tamponade after pericardiocentesis reveals bloody fluid. Her blood pressure equalizes across all four cardiac chambers during diastole. This equalization of diastolic pressures explains which clinical sign?

Accepted Answer

Pulsus paradoxus

Answer

Equalized diastolic pressures from pericardial compression cause inspiratory-dependent ventricular competition, reducing LV stroke volume and SBP by >10 mmHg with each breath.

Question 5

In the setting of acute myocardial infarction, early reperfusion can paradoxically cause cell death through which mechanism?

Accepted Answer

Reperfusion injury from calcium overload, reactive oxygen species, and mitochondrial permeability transition pore opening

Answer

Restored blood flow delivers oxygen to cells with depleted antioxidant defenses, generating ROS that open the mitochondrial permeability transition pore, leading to additional cardiomyocyte death.

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MD - Doctor of Medicine Practice Test

MD Cardiovascular System Pathophysiology 5