Two step cardiomyoplasty with vascular delay: effect of stimulation of latissimus dorsi muscle on diastolic function

A common concern in cardiomyoplasty is whether latissimus dorsi muscle (LDM) stimulation impairs diastolic function. This study determined the time course of left ventricular (LV) contraction and relaxation and their relationship to the diastolic function. Ten mongrel dogs underwent vascular delay of the left latissimus dorsi muscle 2 weeks before cardiomyoplasty. Fourteen to 18 days later, the effects of LDM stimulation were evaluated. Our study demonstrated that LDM stimulation significantly increased peak LV systolic pressure (131.3 +/- 7.5 to 152.0 +/- 7.5* mm Hg), +dP/dt (1585 +/- 151 to 2088 +/- 176 x mm Hg/s), stroke volume (10.8 +/- 1.5 to 13.8 +/- 1.9* ml), stroke work (17.2 +/- 2.7 to 25.6 +/- 3.8* gm x m), and peak aortic flow (4751 +/- 698 to 6712 +/- 926* ml/min), and significantly decreased the pre-ejection time (113.9 +/- 12.6 to 92.3 +/- 7.8* ms) and total systolic time (366.0 +/- 26.9 to 333.6 +/- 21.3* ms) (*p < 0.05). As for diastolic function, LDM stimulation decreased -dP/dt (-1462 +/- 116 to -1781 +/-116* mm Hg/s) and tau (64.0 +/- 6.1 to 52.1 +/- 2.9* ms). The diastolic filling time (Tdf) was significantly longer (177.9 +/- 17.6 to 213.7 +/- 18.7* ms) during the beat immediately after LDM stimulation. These changes reflected an overall stronger contraction and faster relaxation. Our results imply that with vascular delay, stimulation of LDM not only assists systolic function but also improves diastolic function in cardiomyoplasty.