Optimal vascular delay in cardiomyoplasty following latissimus dorsi muscle isolation in dogs

Background and Purpose: Distal ischemia of the latissimus dorsi muscle (LDM) during cardiomyoplasty is a recognized complication that can reduce the muscle's function and mechanical effects. A 2-week vascular recovery period is recommended to allow revascularization and adhesion to the heart. It is not clear, however, that a 2-week vascular delay is optimal after LDM isolation. This study was designed to evaluate both the regional blood flow (RBF) in canine LDM flaps immediately after perforators were ligated, and the effect of 1-, 2-, and 3-week vascular delays on the regional perfusion of LDM flaps without electrical stimulation. Materials and Methods: A catheter-access device connected to the left atrium was implanted in the left back subcutaneous layer in each of six adult mongrel dogs when the LDM was dissected. Five different colored microspheres were injected at five different time points: pre-and post-dissection, and after 1-, 2-, and 3-week vascular delays. At each time point, reference blood was withdrawn from the femoral artery at a fixed speed. The LDMs were removed post mortem for RBF determination. Both tissue and reference blood samples were spectrophotometrically processed to quantify the amount of dye. Results: Proximal RBF did not decrease immediately after dissection when compared to the control (0.28 ± 0.10 vs 0.26 ± 0.05 mL·g^-1·min^-1, p > 0.05), but it decreased after a 1-week vascular delay (0.11 ± 0.02 vs 0.26 ± 0.05 mL·g^-1·min^-1, p < 0.01), and then returned to normal after a 3-week vascular delay (0.21 ± 0.06 vs 0.26 ± 0.05 mL·g^-1·min^-1, p > 0.05). RBF decreased immediately after dissection in the middle and distal segments, and did not return to the control value even after a 3-week vascular delay. Conclusion: RBF in the LDM was depressed by surgical dissection in this canine model. Without electrical stimulation, the middle and distal portions of the LDM remained compromised even after a 3-week vascular delay. The clinical effects of progressive programmed electrical stimulation of the LDM at different periods of vascular delay remain to be studied.