Real-time adjustment of ventricular restraint therapy in heart failure☆

OBJECTIVE: Current ventricular restraint devices do not allow for either the measurement or adjustment of ventricular restraint level. Periodic adjustment of restraint level post-device implantation may improve therapeutic efficacy. We evaluated the feasibility of an adjustable quantitative ventricular restraint (QVR) technique utilizing a fluid-filled polyurethane epicardial balloon to measure and adjust restraint level post-implantation guided by physiologic parameters. METHODS: QVR balloons were implanted in nine ovine with post-infarction dilated heart failure. Restraint level was defined by the maximum restraint pressure applied by the balloon to the epicardium at end-diastole. An access line connected the balloon lumen to a subcutaneous portacath to allow percutaneous access. Restraint level was adjusted while left ventricular (LV) end-diastolic volume (EDV) and cardiac output was assessed with simultaneous transthoracic echocardiography. RESULTS: All nine ovine successfully underwent QVR balloon implantation. Post-implantation, restraint level could be measured percutaneously in real-time and dynamically adjusted by instillation and withdrawal of fluid from the balloon lumen. Using simultaneous echocardiography, restraint level could be adjusted based on LV EDV and cardiac output. After QVR therapy for 21 days, LV EDV decreased from 133+/-15 ml to 113+/-17 ml (p<0.05). CONCLUSION: QVR permits real-time measurement and physiologic adjustment of ventricular restraint therapy after device implantation.