EFFECTS OF CARDIOMYOPLASTY ON BIVENTRICULAR FUNCTION IN CANINE CHRONIC HEART-FAILURE

Dynamic cardiomyoplasty, the use of skeletal muscle to assist the heart, is a new therapy for the treatment of heart failure. However, the effects of cardiomyoplasty on biventricular function and the synchrony of ventricular contraction are not fully known. We assessed the efficacy of latissimus dorsi muscle (LDM) dynamic cardiomyoplasty in a chronic model of biventricular failure. Five dogs received doxorubicin (1 mg . kg-1 . wk-1) for up to 12 weeks to induce heart failure and then underwent a biventricular cardiomyoplasty. After operation, the muscle was progressively stimulated according to an established protocol. When training was complete (10 weeks), radionuclide ventriculographic and catheterization data were obtained. Peak left ventricular (LV) systolic pressure and its first derivative were unchanged, whereas LV end-diastolic pressure decreased slightly with LDM assistance (11.0 +/- 1.6 to 9.6 +/- 1.5 mm Hg; p < 0.05). Right ventricular (RV) systolic pressure increased significantly with LDM assistance from 21 +/- 2 to 26 +/- 3 mm Hg (p < 0.05), whereas its first derivative and RV end-diastolic pressure were unchanged. Dynamic cardiomyoplasty significantly improved LV ejection fraction from 0.18 +/- 0.07 without LDM assistance to 0.31 +/- 0.05 with LDM assistance (p < 0.05); similarly RV ejection fraction increased from 0.32 +/- 0.07 to 0.45 +/- 0.06 with LDM assistance (p < 0.05). The temporal sequence of LV wall motion was assessed by phase analysis of the radionuclide ventriculograms. With skeletal muscle assistance, standard deviation (''spread'') decreased from 31.6 +/- 17.4 to 20.0 +/- 15.4 degrees (p < 0.06), whereas skewness (''symmetry'') was unchanged. Dynamic cardiomyoplasty improved both LV and RV ejection fractions without increasing diastolic pressure. Phase analysis demonstrated that the left ventricle contracted more synchronously, adding support to the use of this new modality in treating the failing heart.