Availability of omental flap on prevention against muscular atrophy of a latissimus dorsi cardiomyoplasty

Dynamic cardiomyoplasty (DCMP) has been performed in more than seven hundreds cases world wide. However, despite symptomatic improvement in the majority of patients surviving the procedure, objective hemodynamic effects have not been consistently demonstrated. Previous studies reported that left ventricular function deteriorated and returned to preoperative level in the chronic phase. We previously reported that atrophy of the latissimus dorsi muscular flap (LDMF) was responsible for the effect of DCMP on improvement of cardiac function in the chronic phase. Ischemia of the muscle flap was proved to induce peripheral muscular atrophy of the flap, and thus preservation of the blood flow is important in preventing muscular atrophy. In the present study, we applied omental flap to LDMF, and postulated that the omentum would improve vascularity and perfusion of latissimus dorsi and prevent peripheral muscle atrophy. In dogs, the right and left latissimus dorsi muscles were dissected free from all attachment except for its thoracodorsal pedicles, and omental flap was wrapped around peripheral part of the left LDMF. Tissue blood flow, maximal muscle isotonic strength, morphologic features, and tissue vascular endothelial growth factor (VEGF) were examined in left LDMF with omental flap (OM group) and in the right LDMF served as the control (Control group). In the distal part of the LDMF, tissue blood flow of OM was significantly preserved than Control (86.4 +/- 6.5% in OM and 33.6 +/- 3.4% in Control, p < 0.05). Maximal isotonic tension was significantly higher in OM as compared to Control. Microscopic findings of H and E stained specimen from distal part of LDMF showed that muscle fibers were preserved in OM. And in the distal part, VEGF expression of OM was 49.6 +/- 7.9 pg/100 micrograms protein and significantly higher than that of Control. Our results indicated that induced endogenous VEGF expression in the LDMF by the omental flap preserved blood perfusion and muscular strength of the LDMF, and suggested that dynamic cardiomyoplasty might not lose its long-term direct cardiac assistance when an omental flap applied for the latissimus dorsi muscle flap.