MEDizzy - A 78-year-old man is admitted to the intensive care unit

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Disorders of the Cardiovascular System

A 78-year-old man is admitted to the intensive care unit with decompensated heart failure. He has long-standing ischemic cardiomyopathy. Electrocardiogram (ECG) shows atrial fibrillation and left bundle branch block. Chest radiograph shows cardiomegaly and bilateral alveolar infiltrates with Kerley’s B-lines. Which of the following is least likely to be present on physical examination?

ExplanationA fourth heart sound indicates left ventricular presystolic expansion and is common among patients in whom active atrial contraction is important for ventricular filling. A fourth heart sound is not found in atrial fibrillation. An irregular heart rate is characteristic of atrial fibrillation. The irregular rate is often characterized as “irregularly irregular.” A third heart sound occurs during the rapid filling phase of ventricular diastole and indicates heart failure. Reversed splitting of the second heart sound occurs with left bundle branch block, as this patient has. Finally, pulsus alternans is beatto-beat variability in pulse amplitude. It is present when only every other Korotkoff sound is audible as the cuff pressure is lowered slowly. It is thought to be due to cyclic changes in intracellular calcium and action potential duration and is associated with severe left ventricular failure.