Improved neoangiogenesis in transmyocardial laser revascularization combined with angiogenic adjunct in a pig model

Recent research has revealed neoangiogenesis as a basic phenomenon in trans myocardial laser revascularization (TMLR). Theoretically, myocardial neoang iogenesis could be further enhanced by the addition of angiogenic growth fa ctors. Triads of TM LR channels were created in the lateral wall of the lef t ventricles of 12 pigs (mean body weight 73 +/- 5 kg), using a holmium:ytt rium-aluminium garnet (YAG) laser. The animals were allocated randomly eith er to receive an injection of 100 mug of a bovine bone-derived growth facto r mixture within the triads (n = 6), or to a control group (n = 6). Animals were killed I month later. Capillary and arteriolar densities were determi ned by computed morphometric analysis of histological sections of the triad s. The capillary density of myocardial areas within the triads was signific antly greater in the group receiving the bovine bone-derived growth factor mixture than in the control group (14.3 +/- 3.5/mm(2) and 5.7 +/- 1.4/mm(2) respectively; P < 0.001). The difference was also significant when conside ring arteriolar density (0.7 +/- 0.4/mm(2) and 0.2 +/- 0.1/mm(2) respective ly; P < 0.001). For comparison, capillary and arteriolar densities of the T MLR channel scars were 48.7 +/- 9.7 and 1.9 +/- 0.5/mm(2) respectively in t he angiogenic group, and 46.3 +/- 13.7 and 2.3 +/- 1.3/mm(2) respectively i n the control group (no significant differences). These results demonstrate that the addition of angiogenic factors to TMLR stimulates neoangiogenesis significantly in the areas adjacent to the channels, but not within the ch annel scars. The latter are themselves strongly vascularized. Hence this co mbined approach, potentiating the effect of TMLR by establishing vascular c onnections between the neovessels of the channel scars, has the potential f or improved clinical outcome.