Differential ventricular ischemic injury: an experimental model of right ventricular failure with a variable degree of left ventricular dysfunction

Abstract

The hemodynamic manifestations of right ventricular dysfunction after ischemic injury depend not only on the severity of injury but also on the degree of coexistent left ventricular dysfunction. A better understanding of right ventricular failure and of optimal therapies has been hindered in part by lack of suitable experimental models of selective and differential ventricular injury. Therefore, we developed a technique of differential ventricular myocardial protection during a period of global cardiac ischemia and examined the effect of such an injury on intrinsic right and left ventricular myocardial function, metabolism, and regional blood flow. Twenty-six dogs were subjected to 30 minutes of ischemia while being supported by cardiopulmonary bypass. During ischemia, right and left ventricular myocardial temperatures were independently varied by selective ventricular endomyocardial thermal regulation. Nine dogs underwent right and left ventricular normothermic ischemia, eight underwent right and left ventricular hypothermic ischemia, and nine underwent right ventricular normothermic and left ventricular hypothermic ischemia. In both ventricles, normothermic ischemia resulted in greater depression of ventricular ability to generate stroke work as a function of end-diastolic dimension (p less than 0.05), greater depletion of myocardial adenine nucleotide content (p less than 0.05), and greater subendocardial reperfusion hyperemia (p less than 0.05). Myocardial temperature of the contralateral ventricle during ischemia had no effect (p = not significant) on intrinsic ventricular functional, metabolic, or regional blood flow response to injury. For a given degree of right ventricular injury assessed by these parameters, the degree of left ventricular injury could be independently varied by as much as 50%. This is a particularly suitable model for the investigation of acute right ventricular failure.