Intracoronary Shunt-Induced Endothelial Cell Damage in Porcine Heart

Abstract

Injury to and dysfunction of the endothelium can compromise the patency of coronary arteries and lead to impaired perfusion of the heart. Such injury can occur after the application of an intravascular shunt and/or a snare to a coronary artery during bypass surgery. In this study, multiphoton microscopy was used to assess the integrity of endothelium in porcine coronary arteries subjected to shunting and snaring during off-pump coronary artery bypass grafting (OPCAB). In open chest porcine, the left anterior descending artery was manipulated in different regions using snare and shunt to simulate OPCAB. Sections of left anterior descending artery were labeled with fluorescent dyes to evaluate the viability of the endothelium. The structural integrity of the endothelium was evaluated by calcein- and ethidium homodimer-mediated fluorescence. Endothelial functional viability was assessed by measuring cellular esterase activity, calcium mobilization, and endothelial nitric oxide synthase-mediated generation of nitric oxide using fluorescence dyes and multiphoton microscopy. Substantial endothelial damage was observed in shunted region of the coronary arteries. In contrast, endothelium remained structurally viable in regions that were snared, similar to control regions of the coronary arteries that were not manipulated. Esterase activity, calcium mobilization, and nitric oxide generation was greater in the control and snared regions of the coronary arteries in comparison to the shunted region. The use of intracoronary shunts led to structural damage and attenuation of endothelial function in porcine coronary arteries, whereas snared vessels maintained their viability and integrity, similar to the control sections. The routine use of shunts in OPCABG may lead to endothelial damage and possibly to long-term graft failure.