Effects of Exercise on Aortic Input Impedance and Pressure Wave Forms in Normal Humans

• Published in: Circulation research 1981-03, Vol.48 (3), p.334-343
• Main Authors: MURGO, JOSEPH P, WESTERHOF, NICO, GIOLMA, JOHN P, ALTOBELLI, STEPHEN A
• Format: Article
• Language: English
• Subjects: Adult; Aorta - physiology; Blood Pressure; Cardiac Output; Catheterization; Heart Rate; Humans; Male; Physical Exertion; Space life sciences; Stroke Volume; Systole; Vascular Resistance
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.res.48.3.334

The effects of supine bicycle exercise on the input impedance of the ascending aorta were studied in thirteen male subjects undergoing cardiac catheterization, but in whom no cardiovascular disease was found. Ascending aortic flow velocity and pressure were recorded simultaneously from a multisensor catheter with an electromagnetic flow velocity probe and a pressure sensor mounted at the same location. A second pressure sensor at the catheter tip provided left ventricular pressure. Fick cardiac outputs were used to scale the velocity signal to instantaneous volumetric flow. Input imped- ance was calculated from 10 harmonics of aortic pressure and flow. For each subject, impedance moduli and phases from a minimum of 15 beats during rest and exercise were averaged. Peripheral resistance decreased from a resting value of 1142 ± 51 (± SE) dynes sec/cm to 712 ± 39 dynes sec/cm during exercise. Characteristic impedance remained unchanged with a resting value of 47 ± 4 dynes sec/cmand an exercise value of 45 ± 4 dynes sec/cm. These results were associated with an increase in aortic pressure (96 ± 2 to 111 ± 2 mm Hg) and pulse wave velocity implying a decrease in aortic compliance. An increase in aortic cross-sectional area apparently offsets the effects of these changes in compliance and pulse wave velocity to result in an unchanged characteristic impedance. The increase in pulse wave velocity caused wave reflections to occur earlier during exercise, but the general characteristics of the pressure wave shapes remained unchanged. Circ Res 48334-343, 1981