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Accelerated myocardial relaxation in conscious dogs during acute cardiac tamponade.
- Source :
-
The American journal of physiology [Am J Physiol] 1994 May; Vol. 266 (5 Pt 2), pp. H1935-43. - Publication Year :
- 1994
-
Abstract
- Eight chronically instrumented conscious dogs were used to test the hypothesis that left ventricular (LV) relaxation is accelerated during cardiac tamponade. The time constant of LV transmural pressure fall was measured before and during intrapericardial (IP) saline infusion (baseline) with and without beta-adrenergic blockade (propranolol 1 mg/kg iv). Heart rate was controlled by atrial pacing. Increasing IP pressure caused a progressive linear decrease in stroke volume before and during beta-blockade in each animal. The time constant of LV transmural pressure fall also decreased continuously with an increase in IP pressure from 26 +/- 7 ms during baseline to 18 +/- 5 ms during severe cardiac tamponade (P < 0.01) before beta-blockade. However, after beta-blockade, the time constant of LV transmural pressure fall was constant over a wide range of IP pressures despite a continuous decrease in LV end-diastolic volume. The time constant of LV transmural pressure fall was not altered by vena caval occlusions that caused the same decrease in LV preload observed during cardiac tamponade. We concluded that despite decreased pump function, LV relaxation was accelerated progressively during graded cardiac tamponade, and this change was dependent not on changes in loading conditions but on an intact beta-adrenergic influence.
- Subjects :
- Acute Disease
Animals
Blood Flow Velocity drug effects
Blood Pressure drug effects
Diastole drug effects
Dogs
Heart Rate
Mathematics
Models, Cardiovascular
Systole drug effects
Ventricular Function, Left drug effects
Cardiac Tamponade physiopathology
Hemodynamics drug effects
Myocardial Contraction drug effects
Propranolol pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0002-9513
- Volume :
- 266
- Issue :
- 5 Pt 2
- Database :
- MEDLINE
- Journal :
- The American journal of physiology
- Publication Type :
- Academic Journal
- Accession number :
- 8203592
- Full Text :
- https://doi.org/10.1152/ajpheart.1994.266.5.H1935