Assessment of Minimally Invasive Device That Provides Simultaneous Adjustable Cardiac Support and Active Synchronous Assist in an Acute Heart Failure Model
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abstract
One of the major maladaptive changes after a major heart attack or cardiac event is an initial decline in pumping capacity of the heart leading to activation of a variety of compensatory mechanisms, and subsequently a phenomenon known as cardiac or left ventricular remodeling, i.e., a geometrical change in the architecture of the left ventricle. Evidence suggests that the local mechanical environment governs remodeling processes. Thus, in order to control two important mechanical parameters, cardiac size and cardiac output, we have developed a minimally invasive direct cardiac contact device capable of providing two actions simultaneously: (1) adjustable cardiac support to modulate cardiac size and (2) synchronous active assist to modulate cardiac output. As a means of enabling experiments to determine the role of these mechanical parameters in reverse remodeling or ventricular recovery, the device was further designed to (1) be deployed via minimally invasive surgical procedures, (2) allow uninhibited motion of the heart, (3) remain in place about the heart via an intrinsic pneumatic attachment, and (4) provide direct cardiac compression without aberrantly inverting the curvature of the heart. These actions and features are mapped to particular design solutions and assessed in an acute implantation in an ovine model of acute heart failure (esmolol overdose). The passive support component was used to effectively shift the EDPVR leftward, i.e., counter to the effects of disease. The active assist component was used to effectively decompress the constrained heart and restore lost cardiac output and stroke work in the esmolol failure model. It is expected that such a device will provide better control of the mechanical environment and thereby provide cardiac surgeons a broader range of therapeutic options and unique intervention possibilities.
