The Annals of Thoracic Surgery, Vol 35, 3-13, Copyright © 1983 by The Society of Thoracic Surgeons
The influence of time on the response to dopamine after coronary artery bypass grafting: assessment of left ventricular performance and contractility using pressure/dimension analyses
P Van Trigt, TL Spray, MK Pasque, RB Peyton, GL Pellom, CM Christian, L Fagraeus and AS Wechsler
Pressure and dimension analyses were used to quantitate the changing
cardiac response to dopamine over a 24-hour interval after coronary artery
bypass grafting (CABG). Ultrasonic dimension transducers were utilized to
measure the minor-axis diameter of the left ventricle, and matched
micromanometers were inserted to measure intracavitary left ventricular
pressure and intrathoracic pressure. Pressure and dimension data were
recorded and analysed by computer during dopamine infusion at 0, 2.5, 5.0,
and 10.0 micrograms per kilogram per minute, at periods designated as early
(2 to 4 hours after CABG) and late (18 to 24 hours after CABG). Myocardial
contractile responses to dopamine (peak velocity of minor-axis shortening,
maximal excursion) were similar at each dose in the early and late studies.
However, overall hydraulic performance, as reflected by cardiac outputs and
the areas of the pressure/diameter work loops, had augmented late dose
responses. This study suggests a major change in the relationship between
the heart and peripheral control mechanisms that may partially explain
diminishing inotropic requirements over time, in addition to the generally
accepted occurrence of improvement in contractile state and functional
reserve following cardiac operation.
