Abstract 4309: Ventricular Elastic Support Therapy (VEST) Reduces Transmural Pressure and Myocardial Strain
Background: Transmural pressure (TMP) determines myocardial strain and chamber dimensions. Epicardial ventricular support may improve mechanical function and promote reverse remodeling by reducing TMP. HeartNet (Paracor Medical Inc) is an elastic intra-pericardial ventricular support device currently evaluated in the PEERLESS-HF clinical trial. To explore the mechanism of action of VEST, we directly measured the in vivo effects of HeartNet on regional hemodynamics and myocardial strain.
Methods: We instrumented open-chest anesthetized dogs (n=6) with flat silastic-balloon epicardial pressure transducers, intravascular pressure catheters, aortic flow probes, and sonomicronometry crystals. The pericardium was re-approximated. We obtained pericardial, epicardial, LV, and aortic pressures. We measured epicardial segment length (end-diastolic myocardial strain) and LV dimensions throughout the cardiac cycle. Loading conditions were altered by volume infusion, caval occlusion, and LAD ligation to induce regional ischemia / dysfunction. Parameters were obtained in every animal with and without the HeartNet in situ (applied at 45% baseline stretch) and compared.
Results: HeartNet epicardial support was 2.8±0.2 mmHg (mean at end-diastole) and was maintained throughout the cardiac cycle and over a wide range of physiologic filling conditions (LVEDP 0 –15 mmHg) indicating that the device is compliant, elastic, and self-adjusting. TMP and end-diastolic strain were significantly reduced (P<0.01) supporting a mechanism of action for the device. After LAD ligation, HeartNet also reduced TMP (−38±8%, P<0.0001) and end-diastolic strain over the anterior wall. Negative regional stroke work was also lowered (−56±2%, P<0.001) suggesting improved overall ventricular mechanical efficiency. Aortic pressure and LV stroke volume (20±2 vs 22 ±3 mL, P=0.20) was maintained.
Conclusions: These are the first in vivo data to demonstrate that ventricular elastic support therapy improves regional myocardial mechanics throughout the cardiac cycle by reducing transmural pressure and end-diastolic strain. Elastic support therapy may provide significant benefits on acute hemodynamics and chronic remodeling in the failing heart.