Systolic time intervals utilizing ear densitography. Advantages and reliability for stress testing.

Systolic time intervals were determined in 10 volunteer subjects at rest and during a variety of cardiocirculatory stresses to further evaluate the ear densitogram derivative as a replacement for the carotid pulse curve. There was close tracking of the two methods not only for left ventricular ejection time (r = +0.98), but also for pre-ejection period (r = +0.98). The results confirmed that this technically simple and remarkably stable wave form permits reliable measurement of the systolic time intervals both at rest and during the actual performance of stress.