RESUMO
BACKGROUND: In dilated cardiomyopathy (DCM), eliminating or reducing extra-geometric burden to the myocardial cells would directly reduce myocardial wall stress leading to improved LV systolic performance. In acute experiments, we tested whether a passive non-blood contacting CardioClasp device, which employs two indenting bars to reshape the left ventricle (LV), could reduce extra-geometric burden, LV wall stress (LVWS) and improve LV systolic function and contractility without decreasing arterial blood pressure. METHODS: In mongrel dogs (n = 5), 4 weeks of right ventricular pacing (210-220-230-240 ppm) induced DCM with severe heart failure. After placing the CardioClasp device, LV performance was evaluated immediately by measuring hemodynamics, echocardiography, and Sonometrics crystal data. Eleven sonometric crystals were placed into endocardial positions (8 in anterior, posterior, mid-anterior, mid-posterior, apex, base, free and septal wall) and in myocardial (2 as regional) and epicardial (1) positions to assess the LV end-systolic pressure-segment length relationships (ESPSR) and cross-sectional area (ESPAR) relationship. RESULTS: CardioClasp decreased the LV end-diastolic anterior-posterior (A-P) dimensions at two levels (15% and 25%). With CardioClasp, LVWS decreased from 93.1 +/- 7.2 to 59.1 +/- 3.2 g/cm2 (P < 0.05) and fractional area of contraction (FAC) increased from 27.6 +/- 3.8 to 33.1 +/- 3.7% (P < 0.01). Peak LV and arterial pressures, LV +dP/dt, LV -dP/dt, and cardiac output were unaltered with CardioClasp. CardioClasp placement significantly increased the slopes of LV pressure versus anterior-posterior segment relationship from 7.3 +/- 0.6 to 15.8 +/- 1.8 mmHg/mm and septal-free wall segment relationship from 6.3 +/- 0.9 to 9.8 +/- 0.5 mmHg/mm. At both 15% and 25% LV A-P dimension reductions, the slopes of ESPAR showed significant steepening and increased from 10.1 +/- 0.7 (baseline) to 15.5 +/- 1.7 (15% reduction) and 19.0 +/- 1.4 mmHg/cm2 (25% reduction). The larger the reduction, the greater was the steepening of the slopes of ESPSR and ESPAR. CONCLUSIONS: CardioClasp reduced LV diameter and thereby decreased LVWS and increased FAC. CardioClasp was able to reshape the left ventricle, while preserving the contractile mass, which increased the slopes of ESPSR and ESPAR. This reshaping was associated with maintained systolic pressures, cardiac output, and increased contractility.