Right latissimus dorsi cardiomyoplasty augments left ventricular systolic performance

We hypothesized that the right latissimus dorsi cardiomyoplasty augments left ventricular performance. Five dogs underwent staged right latissimus dorsi cardiomyoplasty. Ventricular function was studied 1 to 3 weeks later. Left ventricular pressure was measured with a micromanometer and left ventricular dimensions with piezoelectric crystals. Inferior vena caval occlusion was used to vary preload. Pressure-volume data were collected with the muscle unstimulated and stimulated at 1:2 and 1:1 muscle/heart ratios. The end-systolic pressure-volume relation (mm Hg/mL), stroke work, preload recruitable stroke work, left ventricular end-diastolic volume, and the diastolic relaxation constant were calculated and expressed as mean +/- standard deviation. Stimulated beats at a 1:2 ratio showed an increase in stroke work of 42.1% (978 +/- 381 to 1,390 +/- 449 g.cm; p < 0.01) and preload recruitable stroke work of 28.8% (59.4 +/- 20.7 to 76.6 +/- 11.0 g.cm/cm3; p = 0.05) compared with the unstimulated beats. With the stimulator on at 1:1, smaller changes occurred: stroke work increased 9% (1,167 +/- 390 to 1,273 +/- 363 g.cm; not significant) and preload recruitable stroke work increased 27% (63.9 +/- 22.7 to 80.9 +/- 23.1 g.cm/cm3; p = 0.05). There were no significant changes in the end-systolic pressure-volume relation. The diastolic relaxation constant did not change at 1:1 (36 +/- 9.7 to 37 +/- 6.4 ms; not significant) or 1:2 (36 +/- 9.3 to 39 +/- 8.2 ms; not significant). Left ventricular end-diastolic volume was unchanged at 1:1 (34 +/- 10.7 to 32 +/- 10.3 mL) and at 1:2 (31 +/- 9.0 to 32 +/- 8.7 mL).(ABSTRACT TRUNCATED AT 250 WORDS)