Hypertension, Vol 5, 147-154, Copyright © 1983 by American Heart Association
C Alicandri, FM Fouad, RC Tarazi, EL Bravo and RL Greenstreet
Studies of cardiac performance in hypertension have often been restricted
to cardiac output determinations, although the latter alone are inadequate
for that purpose. To define the range of cardiac performance in
hypertension, the response of left ventricular filling pressure to
increased workload (static exercise) was determined in 39 subjects--eight
normotensive (NT) volunteers, seven patients with borderline hypertension
(BLH), and 24 essential hypertensives (EH), of age-matched groups. A rise
of mean pulmonary wedge pressure (PWP) by 5 mm Hg or more during maximum
handgrip (HG) was considered "abnormal" for a workload (SBP x HR x 10(-3))
increase of greater than or equal to 25%. All NT subjects and all patients
with BLH as well as 16 of the 24 EH (EH-I) showed normal cardiac
performance by this definition. In contrast, PWP increased greater than or
equal to 5 mm Hg during HG in eight patients with EH (EH-II). The
calculated increase in cardiac workload was not significantly different
among the four groups (+5, 5.8, 5.4 and 5.5 respectively). Beta blockade
(propranolol, 10 mg i.v.) slowed heart rate in all subjects and reduced SBP
x HR product in all groups both at rest and during HG. Responses of PWP to
HG were widely divergent in the different patients. However, as a group
those patients with "impaired cardiac performance" before propranolol
(EH-II) had a greater reduction in performance following propranolol than
EH-I or NT. This study suggests that adrenergic support of cardiac
performance might be important in some hypertensive patients with no
evidence of heart failure.
ARTICLES
Sympathetic contribution to the cardiac response to stress in hypertension