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

Dynamic cardiomyoplasty, the use of skeletal muscle to assist the hear t, is a new therapy for the treatment of heart failure. However, the e ffects of cardiomyoplasty on biventricular function and the synchrony of ventricular contraction are not fully known. We assessed the effica cy of latissimus dorsi muscle (LDM) dynamic cardiomyoplasty in a chron ic model of biventricular failure. Five dogs received doxorubicin (1 m g . kg-1 . wk-1) for up to 12 weeks to induce heart failure and then u nderwent a biventricular cardiomyoplasty. After operation, the muscle was progressively stimulated according to an established protocol. Whe n training was complete (10 weeks), radionuclide ventriculographic and catheterization data were obtained. Peak left ventricular (LV) systol ic pressure and its first derivative were unchanged, whereas LV end-di astolic pressure decreased slightly with LDM assistance (11.0 +/- 1.6 to 9.6 +/- 1.5 mm Hg; p < 0.05). Right ventricular (RV) systolic press ure increased significantly with LDM assistance from 21 +/- 2 to 26 +/ - 3 mm Hg (p < 0.05), whereas its first derivative and RV end-diastoli c pressure were unchanged. Dynamic cardiomyoplasty significantly impro ved 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 fr action increased from 0.32 +/- 0.07 to 0.45 +/- 0.06 with LDM assistan ce (p < 0.05). The temporal sequence of LV wall motion was assessed by phase analysis of the radionuclide ventriculograms. With skeletal mus cle assistance, standard deviation (''spread'') decreased from 31.6 +/ - 17.4 to 20.0 +/- 15.4 degrees (p < 0.06), whereas skewness (''symmet ry'') was unchanged. Dynamic cardiomyoplasty improved both LV and RV e jection fractions without increasing diastolic pressure. Phase analysi s demonstrated that the left ventricle contracted more synchronously, adding support to the use of this new modality in treating the failing heart.