PMID: 42964Feb 1, 1979

Role of preload and inotropy in stroke volume regulation at constant heart rate

Scandinavian Journal of Clinical and Laboratory Investigation
A Ilebekk, F Kiil

Abstract

The relationship between preload and inotropy on left ventricular function was studied in anaesthetized open-chest dogs, by measuring left ventricular dimensions and stroke volume before and during saline infusion at different levels of inotropy. Left ventricular dimensions were continuously estimated by recording myocardial chord length (MCL) in the anterior wall of the left ventricle by ultrasonic technique. The effects of isoproterenol, a stimulator of adrenergic beta-receptors (high inotropy), and propranolol, an inhibitor of adrenergic beta-receptors (low inotropy), were examined during right atrial pacing at constant heart rate averaging 161 +/- 5 beats/min. Stroke volume was varied within the range 9.0 +/- 1.7 ml to 28.6 +/- 3.2 ml by increasing inotropy and preload. To increase preload, saline was infused intravenously until end-diastolic MCL increased by about 10% and left ventricular end-diastolic pressure was higher than 10 mmHg. At constant heart rate and blood volume, both before and during saline infusion, end-diastolic MCL was not influenced by isoproterenol or propranolol administration. End-systolic MCL was reduced by raising inotropy. The difference between end-diastolic and end-systolic MCL, the systolic myoc...Continue Reading

Citations

Apr 1, 1978·Scandinavian Journal of Clinical and Laboratory Investigation·A Ilebekk, M M Miller
Aug 1, 1976·The American Journal of Physiology·K T WeberL L Hefner
Jul 11, 1975·Circulation·S J ShubrooksJ W Harthorne
Aug 1, 1975·The Journal of Physiology·C T KappagodaH M Snow
Dec 1, 1969·Scandinavian Journal of Clinical and Laboratory Investigation·B Bugge-Asperheim, F Kiil
Feb 1, 1972·Scandinavian Journal of Clinical and Laboratory Investigation·B Bugge-AsperheimF Kiil
Feb 1, 1972·Scandinavian Journal of Clinical and Laboratory Investigation·J LekvenF Kiil
Nov 1, 1969·The American Journal of Physiology·K WildenthalJ H Mitchell
Sep 1, 1969·The American Journal of Physiology·K WildenthalJ H Mitchell
Sep 11, 1966·The American Journal of Physiology·R R TaylorR H McDonald
May 12, 1915·The Journal of Physiology·S Kozawa

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