Cellular destruction following transmyocardial laser revascularization (TMR)

Area of Science:

• Cardiovascular Surgery
• Cell Biology
• Pathology

Background:

• Transmyocardial revascularization (TMR) utilizes high-energy lasers to create channels in the myocardium.
• The precise mechanisms and structural features of cardiomyocyte (heart muscle cell) destruction during TMR remain incompletely understood.

Purpose of the Study:

• To investigate the structural characteristics of myocardial cellular death after transmyocardial revascularization.
• To identify the types of cell death (apoptosis vs. necrosis) occurring in cardiomyocytes adjacent to laser channels.

Main Methods:

• Analysis of myocardial tissue from three male patients within 11 days post-TMR.
• Utilized immunohistochemistry with antibodies against pro-apoptotic proteins CPP32 and BAX.
• Employed electron microscopy to examine the ultrastructure of laser channels and surrounding cardiomyocytes.

Main Results:

• Immunohistochemistry revealed cells expressing CPP32 and BAX along the laser channels, indicating apoptosis.
• Electron microscopy showed laser channels lined with acellular debris and dead cells, lacking endothelialization.
• Surrounding cardiomyocytes exhibited features consistent with both necrotic and apoptotic cell death.

Conclusions:

• Transmyocardial revascularization induces both apoptotic and necrotic cell death in cardiomyocytes.
• The laser channels are characterized by cellular debris and dead cells, without evidence of new blood vessel formation (endothelialization).
• Understanding these cell death pathways is crucial for evaluating TMR efficacy and safety.