VARIABLE EFFECTS OF CARDIOMYOPLASTY ON LEFT-VENTRICULAR FUNCTION

Cardiomyoplasty (CMP) has been considered as a possible treatment for patients with heart failure. Symptomatic improvements occur almost uni formly among survivors with CMP, but changes in left peak ventricular systolic pressure (PVSP) and stroke volume vary in patients. This stud y examined whether there is variability present shortly after cardiomy oplasty surgery. Cardiomyoplasty was performed in 11 mongrel dogs with normal ventricular function. Nine to twelve days after CMP, left vent ricular (LV) function was evaluated by simultaneously measuring LV vol ume (conductance catheter) and pressure (Millar catheter). The latissi mus dorsi muscle (LDM) was stimulated synchronously with ventricular s ystole in a ratio of 1:4 to 1:7 to avoid muscle fatigue. Data were ana lyzed on a beat by beat basis. The PVSP, and maximum dP/dt (+dP/dt) in creased, but the absolute value of minimum dP/dt (-dP/dt) decreased in stimulated beats in 7 dogs while 4 dogs did not respond. The net chan ges in stimulated beats versus nonstimulated beats of PVSP were 6.1 +/ - 1.8 mm Hg (4.3%), of stroke work was 4.5 +/- 1.9 gm.m (29.5%), of +d P/dt was :185 +/- 47 mm Hg/s (8%), and of -dP/dt was 168 :+/- 43 mm Hg /s (7.8%) (p < 0.05) for all these net changes in the responding group while these variations were not significant in the nonresponding grou p. From the results of our study, active LDM assist improves left vent ricular systolic function, occurring in only 7 of 11 experiments. This improvement is inconsistent and varied individually. The :integrity o f the LDM, tightness of wrapping, and adhesions might contribute to th e variability which is present early after surgery and before the LDM is converted into a fatigue resistance muscle.