MEDICAL APPARATUS FOR NON-INJURING MEASUREMENT OF CHARACTERISTICS OF CARDIAC VESSEL

摘要

A medical instrument includes a noninvasive pulse transducer which senses heart beats of a human subject. Based upon pulse signals from the transducer, the instrument provides visual stimulae which allow the human subject to voluntarily synchronize the subject's respiration cycles with the subject's heart beats. At the same time, the instrument determines and stores the instantaneous beat-to-beat heart rate for each beat of the respiratory cycles. After a predetermined number of synchronized respiratory cycles have been completed, the instrument performs both classical statistical and rhythmometric analyses utilizing the stored instantaneous heart rates. The instrument determines from these analyses mean and standard error values for each beat of the respiratory cycle; an analysis of variance of the mean value; a rhythm qualified mean heart rate value; an amplitude value; a timing value (which indicates the location of the peak of the cosine curve best fitting the heart rate data within the respiratory cycle), and a percent rhythm value (which indicates the quality of the fit with the cosine curve to the stored instantaneous heart rates). The amplitude value provides an indication of the physiological (as opposed to chronological) cardiovascular age of the human subject, since it indicates the compliance of the heart tissue. The effect of cardiotoxins, cardiac drugs, other substances, as well as altered physiologic states upon a subject's heart tissue compliance also can be monitored using the amplitude, mean and peak timing values produced by the instrument. The instrument provides a displayed and/or printed output so that the subject or his or her physician has a simple yet accurate indication of heart condition which may be evaluated periodically and followed over time.