Characterizing ventricular mechanics and energetics following repeated coronary microembolization

Myocardial mechanics and energetics were investigated in an animal model of moderate chronic heart failure (CHF) created by repeated coronary microembolizations in six dogs. The final fractional area change was 34 ± 4%. Hearts of these animals were isolated and cross-perfused, and balloons were placed in the left ventricle (LV). Chamber contractile state was markedly depressed in embolized hearts as assessed by the slope (E(es): 2.74 ± 0.49 vs. 4.00 ± 1.18 mmHg/ml, P < 0.01) and volume axis intercept (V₀: 8.7 ± 5.9 vs. 1.0 ± 3.2 ml, P < 0.01) of end-systolic pressure-volume relation compared with a group of six normal dogs. The end-diastolic pressure-volume relation of embolized hearts was shifted to the right, indicating a dilation of the LV. However, systolic and diastolic stress- strain relationships were similar in the two groups, suggesting that the average myocardial properties of the embolized hearts are similar to those of normal hearts. The relationship between oxygen consumption and pressure- volume area in embolized hearts had smaller intercept (2.98 ± 0.44 vs. 3.92 ± 0.39 x 10^-2 ml O₂ · beat^-1 · 100 g LV^-1 P < 0.01) compared with the control group, with no change in the slope. These results contrast with previous findings in pacing CHF and serve as an important characterization of ventricular properties in this model of CHF from different etiology.