MYOCARDIAL INJURY IN THE MOUSE INDUCED BY TRANSTHORACIC CAUTERIZATION

A simplified transthoracic procedure using electrocauterization was us ed to induce myocardial injury in mice. After a single small incision through the skin and dissection of the underlying musculature, a modif ied electrocautery probe consisting of an insulated 20-gauge blunt nee dle with a polyethylene sleeve was inserted through the interior inter costal muscle at the fourth intercostal space and positioned on the an terior surface of the heart. The placement of the probe on the heart w as indicated by mechanical motion of the exterior section of the needl e. Electrocautery was applied to the distal exposed end of the probe. Of 10 mice that underwent this procedure, nine survived. After 10 days , myocardial damage was assessed by visual and histologic examination of the heart. In eight of nine surviving mice, transmural injury was i nduced in the left ventricle, The region of myocardial tissue damage o n the surface of the left ventricle was 4.6 +/- 0.5 mm in diameter. Th is method provides a simple, noninvasive technique using a transthorac ic electrocautery procedure to induce myocardial injury in the mouse h eart with a low incidence of postoperative mortality.