Effects of Stimulated Free Latissimus Dorsi Muscle Graft on LVEDV and LVSW: A New Dynamic Cardiomyoplasty Technique

: The effectiveness of dynamic cardiomyoplasty (DCMP) remains controversial. We hypothesized that effectiveness of DCMP using the latissimus dorsi muscle graft (LDMG) depends on the wrapping method. We analyzed pressure-volume relations (PVR), the left ventricular stroke work (LVSW), and the left ventricular end diastolic volume (LVEDV) changes during nonstimulation and stimulation of the LDMG to evaluate the effect of a new wrapping method of DCMP on the LVSW and the LVEDV changes. The new wrapping technique was evaluated in an acute animal experimental model. In 12 mongrel dogs, we performed continuous measurement of the dimensional and pressure dates of the left ventricle (LV) after the DCMP. The measurement was performed 15 min after wrapping during 5 periods. The duration of one measurement period was 15 s. The animals were divided into 2 groups according to the wrapping method. The heart was wrapped with the LDMG using 2 different methods. For Method 1, Carpentier's method, the heart was wrapped primarily with the distal part of the LDMG, the lateral segment. The vasculoneural pedicle of the latissimus dorsi muscle (LDM) was preserved. For Method 2, the LDM was separated, and the vasculoneural pedicle was cut. The medial sternotomy was performed. The thoracodorsal artery of LDMG was anastomosed to the right internal mammary artery, and the thoracodorsal vein was anastomosed to the right atrial appendage. The heart was wrapped primarily with the proximal part of the “free LDMG,” the transverse segment. Based on the PVR loops, the changes of the LVSW and the LVEDV in both experimental groups were analyzed. The paired t-test was used for statistical analysis. Using Method 1, the LVSW and the LVEDV showed no significant changes during stimulation (stim) of the LDMG, compared with non-stimulation (nonstim) (LVSW: nonstim, 970 ± 168 erg × 103; stim, 1,181 ± 203 erg ± 103; p = 0.126 and LVEDV: nonstim, 36.6 ± 6.7 ml; stim, 37.2 ± 6.8 ml; p = 0.36). Using Method 2, the LVSW was increased, and the LVEDV was decreased during stimulation of the free LDMG, compared with nonstimulation (LVSW: nonstim, 694 ±117 erg ± 103; stim, 846 ± 104 erg ± 103; p < 0.001 and LVEDV: nonstim, 47.7 ± 2.8 ml; stim, 46.8 ± 2.7 ml; p < 0.001). The stimulated free LDMG wrapping of the heart seems to be a more effective wrapping method for DCMP, and it results in an increase of the LVSW and a decrease of the LVEDV, compared with the original Carpentier's rnethod.