Prolonged left ventricular ejection time in the post-premature beat. A sensitive sign of idiopathic hypertrophic subaortic stenosis.

Failure of the pulse pressure to increase in the post-premature beat is considered characteristic of idiopathic hypertrophic subaortic stenosis (IHSS). The sensitivity and specificity of this response were compared to the change in left ventricular ejection time (LVET) in 12 patients with IHSS, in ten control patients with valvular aortic stenosis (AS) and in five normal subjects. The post-PVC pulse pressure increased in all normals and in nine of the ten patients with AS. In IHSS this response was inconsistent. A positive Brockenbrough sign was seen in only 33%. On the other hand, LVET increased greater than 20 msec in eleven of twelve patients with IHSS, whereas all normal subjects and all patients with AS showed either decreases in LVET or increases smaller than 20 msec. Prolongation of the LVET during the post-PVC beat greater than 20 msec appears, therefore, to be a more sensitive sign of IHSS than the corresponding change in pulse pressure.