The influences of age and hypertension on electrical/electromechanical systole ratio (QT/QS2) changes induced by isometric exercise (75% of maximal voluntary contraction) were studied. The study population was divided into four groups: group 1 - 15 healthy subjects aged <60 years; group 2 - 10 healthy subjects aged ≥ 60 years; group 3 - 14 hypertensive patients aged <60 years, and group 4 - 17 hypertensive patients aged ≥ 60 years. Ten normal subjects and 10 hypertensive patients repeated the test after beta-blockade was induced acutely and chronically, respectively. Heart rate and blood pressure changes did not distinguish normal subjects from age-matched hypertensive patients. QT/QS2 significantly increased only in group 1 subjects. Acute propranolol administration prevented ratio increase in normal subjects; after chronic treatment with beta-blocking agents, handgrip induced a significant decrease in QT/QS2 values in hypertensive patients. QT/QS2 changes induced by isometric exercise are affected both by age and hypertension, both of which cause a reduced beta-adrenergic sensitivity.
|Number of pages||6|
|Journal||American Journal of Noninvasive Cardiology|
|Publication status||Published - 1989|
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine