Abstract

Cardiovascular and hemodynamic reactivity was evaluated with M-mode echocardiography, phonocardiography, and carotidography in correlation with circulating catecholamine levels in 25 normotensive subjects, 15 borderline hypertensive patients, and 42 mildly hypertensive patients during isometric exercise at 30% of the maximum force for 3 minutes. At rest, norepinephrine and epinephrine levels were significantly higher, and the cardiac index was similarly increased in both groups of hypertensive patients, but the cardiac mass index was significantly increased only in the mildly hypertensive group. During isometric exercise, the sympathoadrenal reactivity as well as the pressor and chronotropic responses were similar in normotensive subjects and both groups of hypertensive patients. However, the variations in blood pressure were achieved through totally different hemodynamic mechanisms in normotensive subjects and hypertensive patients. In normotensive subjects, the increase in blood pressure could be linked mainly to an increase in cardiac contractility and performance, whereas in either group of hypertensive patients, the increase in blood pressure was mainly associated with an increase in peripheral resistance. These observations are consistent with the hypothesis of a blunted beta-adrenergic reactivity and a predominance of alpha-adrenergic vascular reactivity in borderline and mildly hypertensive patients. This phenomenon, which appears to be unrelated to age or severity of hypertension, could be an important mechanism underlying the development of hypertension in humans.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.