Reduction of infarct size following acute coronary occlusion by augmenting collateral blood supply induced by infusion of tricyclic antidepressants.

Previously, it has been shown that following occlusion of the left anterior descending artery (LAD) in cats, i.v. administration of tricyclic antidepressants (TCAD) significantly decreases the incidence of ventricular fibrillation (VF), which terminates spontaneously upon appearance. Furthermore, this treatment significantly decreases the size of the unperfused ventricular muscle (ischemic myocardium) from 44%-84% (mean 61%) to 17%-56% (mean 34%). This latter effect was demonstrated by using color demarcation of the perfused myocardium with the injection of a dye into the left atrium after 2 h of LAD occlusion in both control and treated cats. It was assumed that reduction of the unperfused area was due to an increase of collateral blood supply to the ischemic area. Although the beneficial effect of TCAD on the collateral blood supply has been clearly demonstrated in cats randomly assigned to two groups, the present study was designed to investigate the changes in the size of the ischemic area in the same animal by using two different dyes. Both dyes were injected into the left auricle after the LAD occlusion: The first was injected before the TCAD treatment and the second after the treatment. Two days after fixation in 4% formaldehyde, the hearts were sliced into three or four transverse sections. Examination of the sections indicated that there were three types of myocardial markings: (a) totally unperfused myocardium; (b) an area perfused by both colors; (c) an area perfused only by the second dye, indicating an increased collateral blood supply, the effectiveness of which was increased by the TCAD treatment.(ABSTRACT TRUNCATED AT 250 WORDS)