Ventricular fibrillation. Its effect on myocardial flow, distribution, and performance

Area of Science:

• Cardiology
• Cardiac Surgery
• Physiology

Background:

• Subendocardial ischemia is a risk during cardiopulmonary bypass when the heart is in ventricular fibrillation.
• Conditions promoting ischemia include sustained electrical stimulus, spontaneous fibrillation in hypertrophied ventricles, cardiac distension, and reduced perfusion pressure.

Purpose of the Study:

• To identify the conditions under which subendocardial ischemia develops during ventricular fibrillation in hearts undergoing cardiopulmonary bypass.
• To explain the mechanisms impeding adequate myocardial blood flow during fibrillation.
• To present an alternative surgical technique to mitigate ischemic complications.

Main Methods:

• The study analyzes factors contributing to subendocardial ischemia during ventricular fibrillation in the context of cardiopulmonary bypass.
• It examines the interplay of fibrillation forces, intracavitary pressure, and myocardial edema in reducing subendocardial flow.
• The research contrasts the outcomes of ventricular fibrillation with a technique of allowing continuous cardiac beating with adequate perfusion pressure.

Main Results:

• Subendocardial ischemia occurs during ventricular fibrillation due to insufficient blood flow to meet metabolic demands.
• Key impeding forces include fibrillation strength, elevated intracavitary pressure, and myocardial edema.
• Myocardial hypothermia offers limited protection against ischemia when perfusion pressure drops significantly.

Conclusions:

• Ventricular fibrillation during cardiopulmonary bypass leads to subendocardial ischemia.
• Abandoning ventricular fibrillation in favor of continuous cardiac beating with adequate perfusion pressure has eliminated the need for postoperative inotropic drugs in aortic or mitral valve replacement surgeries.