Vascular delay of the latissimus dorsi provides an early hemodynamic benefit in dynamic cardiomyoplasty

Objectives. Dynamic cardiomyoplasty (CMP) as a surgical treatment for chron ic heart failure improves functional class status for most patients. Howeve r, significant hemodynamic improvement with latissimus dorsi muscle (LDM) s timulation has not been consistent. The current protocols do not allow earl y LDM stimulation after CMP surgery. We hypothesized that vascular delay of LDM would increase myocardial assistance after CMP and allow early (48-h) LDM stimulation after CMP. Methods. Mongrel dogs (n = 24) were divided in four groups: 1) controls (n = 6), single-stage CMP; 2) Group ES (n = 6), single-stage CMP with early LD M stimulation beginning 48 h, postoperatively; 3) Group VD (n = 6), vascula r delay of the LDM followed by CMP without early LDM stimulation, and 4) Gr oup VDES (n = 6), vascular delay of LDM (14-18 days), followed by GRIP with early stimulation (48 h postoperatively). Two weeks after CMP, global card iac dysfunction was induced by injecting microspheres into the left coronar y artery. LDM-assisted (S) beats were compared with nonstimulated beats (NS ) by measuring aortic pressure (AoP), LV pressure, aortic now, and by calcu lating first derivative of LV contraction (+/-dP/dt), stroke volume (SV), a nd stroke work (SW). Results. In ES, LDM stimulation had no effect on the hemodynamic parameters . In the other groups, LDM stimulation significantly (p < 0.05) increased A oP, LVP, dP/dt, SV, and SW. However, these increases were much larger in VD and VDES. In VD, IDM stimulation increased peak AoP by 21.5 +/- 3.8 mm Hg, LVP by 22.1 +/- 4.1 min Hg, dP/dt by 512 +/- 163 mm Hg/sec, SV by 10.4 +/- 2.3 mL, and SW by 22.1 +/- 5.4 g/m(-1). Similarly, in VDES, LDR I stimulat ion increased peak AoP by 24.1 +/- 4.7 mm Hg, LVP by 26.2 +/- 4.3 mm Hg, dP /dt by 619 +/- 47 mm Hg/sec, SV by 6.5 +/- 0.7 mL, and SW by 16.7 +/- 4.1 g /m(-1) Conclusions. In dogs with global LV dysfunction, CMP after vascular delay r esulted in a significant improvement in hemodynamic function measured 2 wee ks after surgery. This improvement was not provided by single-stage CMP wit h or without early stimulation. Vascular delay of the LDM before surgery ma y play an important role for early benefit after Chip, shorten the overall muscle training period, as well as increase hemodynamic response to LDM sti mulation. (Ann Thorac Surg 1999;67:1304-11) (C) 1999 by The Society of Thor acic Surgeons.