Chronic counterpulsation with descending thoracic aortomyoplasty improved cardiac function in animals with heart failure

Abstract

Descending thoracic aortomyoplasty uses latissimus dorsi muscle for extraaortic diastolic counterpulsation. We hypothesized that descending thoracic aortomyoplasty could improve ventricular function in dogs (n = 5) with heart failure. The left latissimus dorsi muscle was wrapped around the descending aorta and conditioned for 4 weeks with a burst stimulator (five pulses, 33 Hz, 28 bursts/min). Heart failure was induced by rapid ventricular pacing after conditioning. Left ventricular volume was measured with a conductance catheter. Left ventricular and aortic pressures were measured with a micromanometer. Mean diastolic blood pressure, endocardial viability ratio, left ventricular peak pressure, left ventricular end-diastolic pressure, stroke work, isovolumic relaxation time constant, and the end-systolic pressure volume relation were measured at baseline (after heart failure) and with the descending thoracic aortomyoplasty stimulated at 1:1. Contraction of the descending thoracic aortomyoplasty augmented mean diastolic blood pressure (62 +/- 4 to 71 +/- 3 mm Hg) and endocardial viability ratio (1.0 +/- 0.30 to 1.5 +/- 0.13) (p < 0.05). Left ventricular peak pressure (98 +/- 4 to 88 +/- 3 mm Hg), left ventricular end-diastolic pressure (19 +/- 4 to 14 +/- 4 mm Hg), and stroke work (1048 +/- 124 to 743 +/- 80 mm Hg.cm3) (p < 0.05) were reduced. The end-systolic pressure volume relation increased with descending thoracic aortomyoplasty stimulation (3.7 +/- 0.7 to 4.5 +/- 0.8 mm Hg/mL), and the isovolumic diastolic relaxation time constant significantly decreased (54 +/- 6 to 49 +/- 7 msec) (p < 0.05). We conclude that descending thoracic aortomyoplasty can provide diastolic counterpulsation and reduce stroke work in animals with heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)