Various types of systolic clicks in patients with muscular subaortic stenosis.

Four clinical cases of subaortic hypertrophic muscular stenosis are discussed. All four, in addition to a loud systolic murmur, had a loud systolic click. However, the timing of the click and its relationship to the phase of the carotid pulse were different in each case varying from close to medium and to distant (or midsystolic). The comparison of the sound tracing with the carotid tracing demonstrated that, in each case, a sudden change in acceleration was taking place. In one, the click coincided with the onset of the carotid upstroke; in another, with the first peak of the carotid pulse; in the third, with the trough between first and second peak of the pulse; in the last, with a sudden drop of the pulse at mid-systole caused by sudden obstruction to flow. It is concluded that the clicks were caused by rapid changes of acceleration resulting from the abnormal aortic ejection. Thus, the study of the carotid pulse and of the sound tracing are important for a non-invasive diagnosis together with the echo study of the septum and ventricular wall.