The cyclic burst effect of myostimulator on the thoracic aortomyoplasty

ABSTRACT

BACKGROUND: Descending thoracic aortomyoplasty (DTA) is a simple surgical procedure designed to use patient's own skeletal muscle based on the principle of aortic counterpulsation. Clinical application is limited. We have investigated the acute effect of DTA depending on the surgical configurations and cyclic bursts of stimulator parameter. METHODS: In 14 Mongrel dogs, the left latissimus dorsi muscle (LD) was wrapped around the descending aorta. Pacing leads were placed around the thoracodorsal nerve and sensing lead on the left ventricular apex. Cyclic burst 5-6 pulses were applied. Different surgical configurations are clockwise or counter-clockwise wrapping method of LD and whole type or band type of LD. Millar catheter and Swan-Ganz catheter were introduced to measure hemodynamics. Aorta pressure, right atrial pressure, mean aortic systolic and diastolic pressure, systolic and diastolic time, pulmonary wedge pressure, coronary perfusion pressure, endocardial viability ratio were measured in normal heart and pump failure heart. RESULTS: In normal heart, mean aortic diastolic pressure changed from 49.6+/-15.0mmHg to 55.5+/-17.1mmHg(p=0.012), endocardial viability ratio changed from 1.13+/-0.31 to 1.59+/-0.23 (p<0.001). In pump failure heart, mean aortic diastolic pressure changed from 40.0+/-12.8mmHg to 43.2+/-11.2mmHg(p=0.018), endocardial viability ratio changed from 0.69+/-0.22 to 1.01+/-0.40 (p=0.018). In clockwise configuration, mean aortic diastolic pressure changed from 50.3+/-14.0mmHg to 56.9+/-14.8mmHg(p=0.004). In whole type configuration, mean aortic diastolic pressure changed from 49.814.6mmHg to 57.1+/-15.6mmHg(p=0.003). CONCLUSIONS: Train stimulation of 5-6 pulses and surgical configurations of clockwise rotation with whole LD type play a role to maximize acute effect of DTA.