Effects of free latissimus dorsi dynamic cardiomyoplasty on left ventricular function

In their experimental approach to dynamic cardiomyoplasty (DCMP), the authors hypothesized that a wrapping method using the proximal part of a free latissimus dorsi muscle (LDM) graft might augment ventricular contractility more than the classic Carpentier's wrapping method. The authors divided 12 mongrel dogs into a pedicled LDM graft group (Group 1, n = 6) and a free LDM graft group (Group 2, n = 6) to evaluate the properties of the different wrapping methods. To evaluate the effect of DCMP on left ventricular systolic and diastolic function, the authors used precise indicators that minimize the influences of load conditions. The slope of the linear preload recruitable stroke work relationship (Mw) and an X-intercept (Vo) were utilized as the indicator of left ventricular systolic function. The constants of pressure decay (tau) and peak filling rate (PFR) were measured to determine diastolic function. All experimental animals were evaluated with the acute, non preconditioning model. Mw was significantly increased with LDM stimulation in both groups (postwrap non stimulation 59.1 +/- 6.3; postwrap stimulation 98.6 +/- 9.7 erg.cm-3. 10(3); p < 0.01 in Group 1, postwrap non stimulation 66 +/- 6.7; postwrap stimulation 155 +/- 15.7 erg.cm-3.10(3), p < 0.001 in Group 2). Stimulated free LDM grafts significantly increased the Mw in comparison to pedicled grafts (p = 0.011). Vo was unchanged in both groups and there was no significant difference between the two groups. Tau increased after LDM wrap in both groups (p < 0.05), but there was no difference between the two groups (tau; prewrap 45.8 +/- 6.0; postwrap non stimulation 69.3 +/- 10.3; postwrap stimulation 72.3 +/- 13.9 msec in Group 1, prewrap 50.0 +/- 6.0; post wrap non stimulation 61.8 +/- 5.0; post wrap stimulation in 64.3 +/- 4.7 msec in Group 2). Peak filling rate was unchanged after LDM wrap in both groups. Free LDM grafts significantly increased left ventricular systolic function compared to the pedicled LDM. Although myocardial relaxation was impaired after LDM wrap in both groups, there was no difference between the two groups. The authors' results emphasize the explicit benefit of utilization of a free LDM graft in respect to left ventricular systolic function; the free LDM grafts have no gross detrimental effect on diastolic function when compared with a pedicle graft in the acute model.