Effect of Age

T HE INCREASE of pulse wave velocity with age is well established1-3 and reflects a loss of the elastic properties of the arterial wall.4 The age trends of pulse wave velocity vary for different arteries.2 8 In view of early localization of atherosclerotic changes in the abdominal aorta, we have compared age trends of the aortic pulse wave velocity, measured by impedance plethysmography in normal subjects and in patients with coronary artery disease. Since arterial hypertension as well as age increases the pulse wave velocity,1-6 only normotensive patients were selected for this series. Impedance plethysmography is a convenient method for inertia-free recording of the aortic volume pulse from skin electrodes and eliminates the necessity of intrapolation of records from the subelavian or carotid arteries as in earlier investigations. We have also measured the interval from the earliest QRS deflection in any of simultaneous 3 standard electrocardiographic leads to the foot point of the aortie volume pulse recorded by impedance plethysmogram. This interval consists of the electrical latent period, the period of isometric contraction, and the time from the opening of the aortic valve to the arrival of the pulse wave in the vicinity of the aortic arch. The isometric contraction time is probably the most important of these components. The term "aortic ejection time"7 is used for abbreviation. The effects of age and of coronary artery disease on this interval was studied for the first time.