A double systolic apical impulse is most consistent with the development of mid systolic obstruction to left ventricular outflow. It may rarely be seen in patients with combined aortic stenosis and regurgitation and at the time of a mid systolic click in patients with mitral valve prolapse. A presystolic impulse is the palpable equivalent of an audible fourth heart sound. In the video, note the presystolic component occurs just before the carotid pulse and the double systolic impulse occurs with the carotid pulse.