Intensive Care Medicine (ICM) Practice Exam

Which cardiac condition is characterized by a "water-hammer" pulse?

1. Hypertrophic cardiomyopathy

2. Aortic regurgitation

3. Mitral stenosis

4. Congestive heart failure

The correct answer is: Aortic regurgitation

The characteristic "water-hammer" pulse is associated with aortic regurgitation. This type of pulse is noted for its rapid rise and fall, similar to the surge of water moving through a pipe and then rapidly dissipating. In aortic regurgitation, the backflow of blood from the aorta into the left ventricle during diastole causes a wide pulse pressure—the difference between systolic and diastolic blood pressure. This wide pulse pressure contributes to the prominence of the pulse wave, resulting in the water-hammer sensation. In contrast, hypertrophic cardiomyopathy typically presents with different pulse characteristics due to dynamic obstruction and not with the pronounced rapidity of the water-hammer pulse. Mitral stenosis does not generally produce a water-hammer pulse; instead, it can result in a more subdued pulse due to reduced stroke volume. Congestive heart failure may cause a weak and thready pulse rather than a water-hammer sensation due to decreased cardiac output and perfusion. Understanding the physiological mechanisms behind these conditions helps to further clarify why aortic regurgitation is the correct condition associated with the "water-hammer" pulse.