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| AATS/NHLBI: Cardiothoracic Surgery Exploring Collaborative Clinical Research Opportunities | |||||||||||||||||||||||||||||
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Title and Author Outcomes and Challenges With Current VADsBartley P. Griffith, M.D. Abstract Use of modern, continuous flow ventricular assist devices (VADs) has been associated with improvements in survival and a reduction in adverse events. Remarkable rates of survival are being reported for the most current patient cohorts enrolled in post IDE Continued Access Programs (CAP). These patients received the HeartMate II® (Thoratec Corp., Pleasanton, Calif.) destination therapy or HeartWare® (HeartWare Intl., Inc., Framingham, Mass.) for bridge to transplant. Results reflect an experienced user group that has benefitted from lessons learned during earlier IDE trials and best reflect real-time expectations. These represent a group that have experience with the device and its application to well selected patients.
*CAP cohorts ADVERSE EVENTS Bio-incompatibility: According to INTERMACS, leading causes of death in VAD recipients between 2008-2010 are heart failure (arrhythmia and right heart failure) 22%, infection 16.2%, central nervous system events (stroke)14.1% and multi-organ failure 10.5%. Near current data is available from the pivotal IDE bridge-to-transplant HeartWare trial: Right heart failure (22.7% and 0.29 events/PPY), GI bleeding (10.5% and 0.23 events/PPY), CVA (10% and 0.16 PPY), Sepsis (9.3% and 0.16 events/PPY) and driveline infection (10% and 0.22 events/PPY). Thrombotic obstruction of CF pumps is a serious and not infrequent complication and likely occurs 3-5%. Recently, disturbing rates of GI bleeding from arteriovenous malformations have emerged in CF-supported patients. The etiology and treatment of CF pump-associated arteriovenous malformations and of acquired von Willebrand syndrome is poorly understood. Right Heart Failure: Right ventricular failure and arrhythmia are the leading causes of death (22%) after implantation of an LVAD. Severe right ventricular failure is believed to occur in more than 20% of LVAD patients. Modest smoldering right ventricular failure (CVP>18, CI>2.2) which is also limiting is under reported. Clinicians still have difficulty in predicting post LVAD RV failure. Current options for RVAD are more often "reactive" and limited to short-term paracorporeal support after LVAD implant and preoperative decision to use the pneumatic SynCardia® TAH (SynCardia Systems, Inc., Tucson, AZ). SynCardia® has achieved 79% BTT success but remains too large for all but large patients, and the suitcase-size compassion air compression designed for outpatient use remains unapproved. Key Research Gap Requiring NHLBI Leadership Bio-incompatibility: Much of the adverse events associated with VADs stems from the bio-incompatibilities between the device and patient. For the field to continue to grow, device bio-compatibility and AE must begin to approach those associated with mechanical valves. The current outstanding hydrodynamics and reliability (bearings, motors, drivelines) of current CF VADs is the byproduct of incremental gains in engineering. To date, blood-device bio-incompatibility targets chiefly have been limited to shear forces and exposure times to minimize clinically significant hemolysis. Currently, the NIH is supporting the MCS field. The 2002 Cardiac Surgery Workshop was in part responsible for interest in the development of the recently awarded REVIVE-IT trial (earlier LVAD use) and the PumpKIN contract (pediatric assist). The NHLBI might consider continuing its long-term and pivotal role in development of mechanical circulatory support by generously funding an RFA that addresses the limiting problem of device-patient bio-incompatibility. This will require following the NIH Translational Roadmap which includes multidisciplinary teams. Important advances in design of non-platelet activating or plasma-shearing impellars and hypothrombogenic surfaces are required. Percutaneous plus "TETS" drive systems must evolve. Clinical research targeted to reduce thromboembolism and bleeding is essential.RV Failure: An improved understanding of the RV's ability to reverse remodeling will properly define those most likely to benefit from LVAD alone. A 4"x4" CF total artificial heart has recently been funded, but a development program to consider broader funding in this area would be advantageous. Key Citations 1: Kirklin JK, Naftel DC, Kormos RL, et al. Third INTERMACS Annual Report: The evolution of destination therapy in the United States. J Heart Lung Transplant 2011;30(2):115-1232: Park SJ, Milano CA, Tatooles AJ, et al. Abstract 14430: Outcomes in advanced heart failure with left ventricular assist devices for destination therapy. Circulation 2010;122:A14430 3: Crow S, Chen D, Nilano C, et al. Acquired von Willebrand syndrome in continuous-flow ventricular assist device recipients. Ann Thorac Surg 2010 Oct;90(4):1263-9; discussion 1269 |
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Copyright © 2012 American Association for Thoracic Surgery
All rights reserved. IMPORTANT REMINDER: The preceding information is intended only to provide
general guidance and not as a definitive basis for diagnosis or treatment in any particular case.
It is very important that you consult a doctor about any specific medical problem or question.
All rights reserved. IMPORTANT REMINDER: The preceding information is intended only to provide
general guidance and not as a definitive basis for diagnosis or treatment in any particular case.
It is very important that you consult a doctor about any specific medical problem or question.