What is Quincke's pulse a sign of?

Quincke's pulse, characterized by the capillary pulsations seen at the nail beds, is specifically associated with aortic regurgitation. This phenomenon occurs due to the significant drop in diastolic pressure that results from the backflow of blood from the aorta into the left ventricle during diastole. Consequently, the body compensates by increasing stroke volume to maintain adequate perfusion, which leads to wide pulse pressure. The rapid rise and fall of pressure during the cardiac cycle creates the visible capillary pulsations seen in Quincke's pulse.

In contrast, conditions like aortic stenosis and mitral regurgitation have different hemodynamic profiles that do not produce these characteristic pulsations. Aortic stenosis typically presents with a narrowed outflow tract leading to a more gradual rise in pressure and a reduced stroke volume, while mitral regurgitation results in volume overload of the left atrium, affecting the left ventricle's function differently. Pulmonary hypertension is characterized by increased pressure in the pulmonary arteries and does not relate to the distinct changes in pulse characteristics seen in Quincke’s pulse. Thus, aortic regurgitation is the correct context for interpreting Quincke's pulse.