Water-hammer pulse: A pulse that is full and then suddenly collapses. This type of pulse is also called a Corrigan pulse after the Irish physician Dominic John Corrigan (1802-80) who described this finding in patients with aortic regurgitation caused by a leaky incompetant aortic value in the heart. The left ventricle of the heart ejects blood under high pressure into the aorta. Then the aortic valve normally shuts tight so that blood cannot return to the ventricle. If, however, the aortic valve cannot close completely, the blood in the aorta comes sloshing back into the ventricle and the pressure and the pulse collapse.