Controlled reperfusion following regional ischemia

Area of Science:

• Cardiovascular Science
• Myocardial Reperfusion Injury
• Cardiac Surgery

Background:

• Advances in reperfusion therapies for acute coronary occlusion necessitate understanding their impact on myocardial function.
• Interest in revascularizing ischemic myocardium has grown due to improved fibrinolytic agents and angioplasty techniques.

Purpose of the Study:

• To investigate changes in global ventricular function, mass, and compliance during acute coronary occlusion and subsequent reperfusion.
• To compare the effects of reperfusion in a beating heart versus an arrested heart using blood cardioplegia.

Main Methods:

• Acute coronary occlusion was induced in 17 dogs on cardiopulmonary bypass for 45 minutes.
• Reperfusion was achieved in 12 dogs by releasing a coronary snare in the beating heart.
• In 5 dogs, reperfusion occurred in an arrested heart with a 10-minute infusion of blood potassium cardioplegia.

Main Results:

• Coronary occlusion significantly decreased stroke work index and left ventricular (LV) mass, with no change in compliance.
• Reperfusion in the beating heart increased LV mass and decreased LV compliance compared to pre-ischemia values.
• Reperfusion with blood cardioplegia in the arrested heart maintained LV mass and compliance at control levels.

Conclusions:

• Revascularization of acutely ischemic myocardium in a beating heart model exacerbates LV dysfunction by increasing mass and reducing compliance.
• Using blood cardioplegia for reperfusion in an arrested heart effectively avoids this post-reperfusion damage.
• This suggests a protective strategy for myocardial preservation during cardiac interventions.