Wavefront myocyte injury and relationship to function in right ventricular ischemia

Area of Science:

• Cardiovascular Physiology
• Myocardial Ischemia Research

Background:

• Previous canine studies on right ventricular (RV) ischemia lacked definitive evidence of early irreversible injury due to extensive collateral circulation.
• Canine coronary anatomy differs from humans, limiting its applicability in studying RV ischemia.

Purpose of the Study:

• To investigate the temporal progression of RV global and regional function and myocardial injury following acute right coronary occlusion in pigs.
• To establish a relevant animal model for human RV ischemia due to similar coronary anatomy.

Main Methods:

• Thirty-two closed-chest pigs underwent right coronary occlusion.
• RV function was assessed using biplane ventriculography.
• Myocardial injury was evaluated via immunohistochemical localization of creatine kinase (CK) and electron microscopy.

Main Results:

• Global RV ejection fraction and regional function (apical, midventricular) significantly decreased after 10 minutes of occlusion.
• Myocardial injury progressed in a wavefront from endocardium to epicardium, with significant myocyte injury observed at 10, 30, and 60 minutes.
• A strong correlation (r = 0.96, P < 0.01) was found between regional RV function and the extent of myocardial injury.
• CK immunostaining diminished progressively from the endocardium toward the epicardium with increasing ischemic duration.

Conclusions:

• RV ischemic injury in pigs, possessing human-like coronary anatomy, progresses in a wavefront manner.
• Irreversible myocardial injury occurs within 15-30 minutes of ischemia in this model.
• This study provides critical insights into the pathophysiology and timing of RV ischemic injury.