A 65-year-old male is evaluated in the cardiac intensive care unit for undifferentiated sh… — USMLE Step 2 CK

A $65$ -year-old male is evaluated in the cardiac intensive care unit for undifferentiated shock. A pulmonary artery catheter is placed to obtain precise hemodynamic measurements. Match the following cardiac conditions with their most characteristic right heart catheterization hemodynamic profile.

Constrictive pericarditisEqualization of diastolic pressures with prominent $x$ and $y$ descents and discordant right and left ventricular systolic pressure changes during inspiration
Cardiac tamponadeEqualization of diastolic pressures with a prominent $x$ descent but a blunted or absent $y$ descent
Acute severe mitral regurgitationMarkedly elevated pulmonary capillary wedge pressure with giant $v$ waves and normal right-sided oxygen saturations
Acute ventricular septal defectSignificant step-up in oxygen saturation between the right atrium and the right ventricle
Restrictive cardiomyopathyElevated ventricular filling pressures with left ventricular end-diastolic pressure exceeding right ventricular end-diastolic pressure by $>5$ mm Hg and concordant changes during inspiration

Answer

Constrictive pericarditis matches with discordant pressure changes and prominent

x/y

descents; Cardiac tamponade matches with a blunted

y

descent; Acute mitral regurgitation matches with giant

v

waves; Acute ventricular septal defect matches with an oxygen step-up; Restrictive cardiomyopathy matches with concordant pressure changes and left ventricular end-diastolic pressure > right ventricular end-diastolic pressure.

Each condition produces a distinct and pathognomonic right heart catheterization profile based on its underlying pathophysiology, ranging from external cardiac compression to intracardiac shunting or valvular incompetence.

Step-by-Step Solution

Analyze the hemodynamic profiles of pericardial diseases.

Both tamponade and constriction cause equalization of diastolic pressures, but tamponade lacks a

y

descent while constriction has prominent

x

and

y

descents with discordant respiratory variation.

Differentiates cardiac tamponade from constrictive pericarditis.

Differentiate constrictive pericarditis from restrictive cardiomyopathy.

Restrictive cardiomyopathy has concordant respiratory changes and left ventricular end-diastolic pressure significantly greater than right ventricular end-diastolic pressure.

Both present with prominent

x

and

y

descents and right heart failure, requiring differentiation by respiratory variation and pressure differences.

Analyze the hemodynamic profiles of mechanical complications of myocardial infarction.

Acute mitral regurgitation produces giant

v

waves on the pulmonary capillary wedge pressure tracing, while an acute ventricular septal defect causes an oxygen step-up from the right atrium to the right ventricle.

Distinguishes between two common causes of cardiogenic shock presenting with a new holosystolic murmur.

Key Concept

Hemodynamic profiling via right heart catheterization is essential for differentiating shock states and complex cardiac pathologies, such as pericardial versus restrictive diseases and mechanical complications of myocardial infarction.

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