Lawrence S. Lee, Ravi K. Ghanta, Aravind Rangaraj, Ramanan Umakanthan, Minoru Tabata, Rita G. Laurence, John A. Fox, Ralph M. Bolman, Lawrence H. Cohn, Frederick Y. Chen.
Brigham and Women's Hospital, Boston, MA, USA.
Wrap Tightness Determines Reverse Remodeling with Ventricular Restraint Therapy
Background: Ventricular restraint is a less invasive non-transplant, non-VAD surgical option for heart failure that has shown clinical efficacy in recent multi-center clinical trials. Current techniques and devices, however, do not allow for the quantitative study or application of restraint therapy. We have developed an adjustable and measurable technique of ventricular restraint by placing a fluid-filled epicardial balloon around the entire ventricular surface. Bedside measurement and adjustment of restraint is achieved in a minimally invasive manner by accessing the balloon via a portacath. Wrap tightness is quantified by measuring balloon luminal pressure at end-diastole. In this study, the effect of wrap tightness on reverse remodeling in a chronic ovine model of heart failure was assessed.
Methods: Heart failure developed in 9 sheep 2 months after ligation of diagonal coronary arteries. Animals were divided into 3 equal groups: control, low restraint (1.5 mmHg), and high restraint (3.0 mmHg). Epicardial balloons were implanted and ventricular remodeling was evaluated over 2 subsequent months with weekly echocardiography. Wrap tightness was measured weekly via a portacath. Change in the LV Ejection Fraction (EF), End-Diastolic Volume (EDV), and wrap tightness was then assessed using repeated measures analysis of variance.
Results: Ventricular restraint decreased LV EDV and improved EF in all heart failure sheep (Figure). High restraint decreased EDV to a greater degree (mean Δ = -28%) than low restraint (mean mean Δ = -18%). As the heart reverse remodeled, wrap tightness decreased and there was a resultant decrease in the rate of reverse remodeling. Peak reverse remodeling occurred after 21 days with high restraint and after 35 days with low restraint.
Conclusions: Ventricular restraint wrap tightness affects the rate and degree of improvement in LV EDV. Quantitative restraint therapy can provide an objective method by which therapy is tailored to each individual patient. Periodic adjustment of wrap tightness may be required for optimal restraint therapy efficacy. 
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