The Journal of Thoracic and Cardiovascular Surgery, Vol 79, 812-821, Copyright © 1980 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
The influence of prearrest factors on the preservation of left ventricular function during cardiopulmonary bypass
EG Butchart, MT McEnany, G Strich, C Sbokos and WG Austen
Uniformly excellent myocardial protection during global ischemia in cardiac
procedures requiring cessation of aortic root perfusion remains an elusive
goal. This study establishes the importance of the preischemic inotropic
state of the left ventricle and the arterial blood glucose concentration
([glucose]) immediately prior to an elective period of myocardial ischemia.
Thirty-one experiments were performed on dogs subjected to 90 minutes of
global ischemia on cardiopulmonary bypass at 28 degrees C with perfusion
pressure constantly maintained at 90 mm Hg. The maximum rate of development
of left ventricular pressure (LVdp/dtmax) at constant arterial and left
atrial (LAP) pressures was used as a measure of contractility prior to
ischemia. In a group of 18 of these dogs undergoing anoxic cardiac arrest,
arterial blood [glucose], in conjunction with the preischemic LVdp/dtmax
and the cross-clamp to asystole time interval (metabolic supply/demand
index), significantly predicted (p less than 0.01) the functional result
following the standard ischemic insult. In 13 other dogs with [glucose]
greater than 120 mg/100 ml and treated with potassium cardioplegia,
"normal" preischemic LVdp/dtmas (N = 7) was associated with a good
functional result, but an elevated preischemic LVdp/dtmax (N = 6) produced
severe functional impairment following ischemia. Optimum myocardial
protection thus involves minimizing metabolic demands and maximizing
metabolic supply immediately prior to and during the period of aortic
cross-clamping.
