Conversion of the TandemHeart percutaneous ventricular assist device to long-term support
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《血管的通路杂志》
H165, Division of Cardiothoracic Surgery, The Pennsylvania State University Heart and Vascular Institute/Hershey Medical Center, 500 University Drive, Hershey, Pennsylvania, PA 17033, USA
Abstract
The TandemHeart percutaneous ventricular assist device (VAD) has been employed at our institution to support a diverse group of patients. Patients that fail to demonstrate ventricular recovery must be transitioned to more definitive ventricular assist device support. We report utilization of the TandemHeart femoral cannulae as conduits for cardiopulmonary bypass as an operative strategy to facilitate implantation of a more durable VAD system.
Key Words: Heart assist devices; TandemHeart; Cardiopulmonary bypass
1. Introduction
We recently supported a patient with peri-partum cardiomyopathy and acute hemodynamic collapse with the TandemHeart (CardiacAssist, Inc., Pittsburgh, PA) as a left VAD. Despite overall clinical improvement, the patient could not be weaned from support and required transition to a more definitive VAD while awaiting cardiac transplantation. The TandemHeart femoral cannulae proved useful in facilitating cardiopulmonary support as we undertook implantation of a Thoratec pneumatic VAD.
2. Case report
This 29-year-old woman presented to our institution after management closer to home for a peri-partum cardiomyopathy. The patient had a precipitous decline in end organ function and was transferred to our institution for urgent evaluation. Despite aggressive inotrope therapy that was initiated prior to her transfer, the patient continued to manifest deteriorating end organ function. After discussion with the patient's family about the implications of her clinical condition, she was taken to the cardiac catheterization laboratory for urgent implantation of the TandemHeart assist device. Our patients are managed under the combined care of cardiology and cardiac surgery, and decisions and implantation were undertaken as a joint effort. The patient had immediate improvement in perfusion manifest by normalization of renal function, preserved neurologic function and weaning of inotrope therapy. Flows were maintained at 3–4 l/min throughout her course. Despite effective cardiac unloading, the patient had persistent left ventricular dysfunction, and failed subsequent circulatory support weaning attempted at five days of support. During this time the patient underwent an extensive work-up and was deemed a suitable candidate for cardiac transplantation. Limitations of percutaneous support include device reliability and patient immobility. The patient and family were approached about more definitive circulatory support and agreed to proceed with conversion of her device to a Thoratec (Pleasanton, CA) pneumatic LVAD.
The patient was taken to the operating room on her sixth day of percutaneous VAD support. The cannulation scheme for the TandemHeart has been described previously [1,2]. The pump and configuration of the cannulae are shown in Fig. 1. Pump outflow is returned through a percutaneous Bio-Medicus (Medtronic, Inc., Minneapolis, MN) femoral arterial cannula. Inflow to the pump is provided by a cannula inserted with fluoroscopic guidance via the femoral vein directed into the left atrium by septal puncture. The pump is capable of providing up to 4 l/min of flow [3]. As we prepared to convert the patient to more definitive support we speculated that the TandemHeart cannulae would be well suited to provide access for cardiopulmonary support. In the operating room, the patient was evaluated by transesophageal echocardiography. It was apparent that her left ventricular function would not tolerate weaning of circulatory support, even with appropriate loading conditions and the addition of inotrope support. The patient's right heart function appeared preserved. The pump cannulae were incorporated into the surgical field. Echocardiographic evaluation revealed no thrombus within the left heart. A median sternotomy was undertaken and exposure for VAD implantation was completed. The patient underwent complete systemic heparinization in anticipation of initiating cardiopulmonary bypass (CPB). Under echocardiographic guidance, the left atrial cannula was carefully withdrawn until the tip was identified in the inferior portion of the right atrium. The pump was turned off just prior to beginning these manipulations. In turn the cannulae were separated from the TandemHeart, and attached directly to the CPB circuit. The patient subsequently underwent institution of bypass and we were able to maintain flows of 4 l/min with complete decompression of the heart, and the patient underwent uncomplicated implant of the Thoratec VAD. The patient was weaned without difficulties from CPB after completion of the implant procedure. She had excellent VAD and hemodynamic parameters, and echocardiographic confirmation of appropriate left ventricular unloading by the Thoratec device. The cannulae were approached by open exposure of the femoral vessels at the time of protamine administration, and removed with uncomplicated repair of the femoral vessels. We believe that the size of the cannulae mandate an open approach to femoral vessel repair. Addtionally, this approach coupled with attention to detail at the time of percutaneous access of the femoral vessels at the time of implant has likely contributed to our avoidance of cannula-related complications.
The patient's post-operative course was uncomplicated and she was discharged to home where she now awaits a suitable donor for transplantation.
3. Discussion
Over the six months since acquiring this device at our institution, we have successfully supported to discharge all six patients treated with the TandemHeart. To date we have reserved this device for patients we believed to be candidates for short periods of support and anticipated weaning of circulatory assistance. This patient is one of several that we have supported in profound cardiogenic shock at the time of implant of the device. We have obtained maximal flow rates of 4.5 l/min. Despite our concerns about flow limitations, we have not been faced with incomplete heart decompression or inadequate systemic support with this device; though we concede that our series to date remains small.
The patient described is the first we have encountered that required transition to more definitive VAD support. Conversion from percutaneous to definitive support is certainly not complicated, and, we have made all efforts to streamline this process. We continue to utilize CPB for implantation of all long-term devices. The cannulation scheme that we describe facilitates initiation of CPB and rapid VAD conversion. The transition of the TandemHeart cannulae to a CPB circuit was straight forward, limited aortic manipulation, and eliminated the need for right atrial instrumentation. We had no difficulties with providing adequate CPB flows for our patient. Additionally, in the event of incomplete cardiac decompression, or the need for right atrial access, flow could certainly be augmented by incorporation of a small superior vena cava cannula into the circuit. Finally, the Bio-Medicus cannula utilized for percutaneous return is chosen at the discretion of the implanting physician. Cannula size should be considered at implant, to assure that arterial flow can be matched to the patient's size when our cannulation scheme is utilized. Growing experience with successful support of patients with the TandemHeart provides an additional option for patients with profound cardiac failure. An expanded group of circulatory assist devices allows matching the most suitable pump to individual patient needs. We believe the cannulation scheme described in this report is a small but unique step towards assuring the most efficient and safest utilization of this technology for these critically ill patients.
References
Kar B, Butkevich A, Civitello AB, Nawar MA, Walton B, Messner GN, Gregoric ID, Feldman J, Myers TJ, Gemmato C, Delgado RM III. Hemodynamic support with a percutaneous left ventricular assist device during stenting of an unprotected left main coronary artery. Tex Heart Inst J 2004; 31:84–86.
Vranckx P, Foley DP, de Feijter PJ, Vos J, Smits P, Serruys PW. Clinical introduction of the TandemHeart, a percutaneous left ventricular assist device, for circulatory support during high-risk percutaneous coronary intervention. Int J Cardiovasc Intervent 2003; 5:35–39.
Pitsis AA, Dardas P, Mezilis N, Nikoloudakis N, Filippatos G, Burkhoff D. Temporary assist device for postcardiotomy cardiac failure. Ann Thorac Surg 2004; 77:1431–1433.(Sanjay Mehta and Walter P)
Abstract
The TandemHeart percutaneous ventricular assist device (VAD) has been employed at our institution to support a diverse group of patients. Patients that fail to demonstrate ventricular recovery must be transitioned to more definitive ventricular assist device support. We report utilization of the TandemHeart femoral cannulae as conduits for cardiopulmonary bypass as an operative strategy to facilitate implantation of a more durable VAD system.
Key Words: Heart assist devices; TandemHeart; Cardiopulmonary bypass
1. Introduction
We recently supported a patient with peri-partum cardiomyopathy and acute hemodynamic collapse with the TandemHeart (CardiacAssist, Inc., Pittsburgh, PA) as a left VAD. Despite overall clinical improvement, the patient could not be weaned from support and required transition to a more definitive VAD while awaiting cardiac transplantation. The TandemHeart femoral cannulae proved useful in facilitating cardiopulmonary support as we undertook implantation of a Thoratec pneumatic VAD.
2. Case report
This 29-year-old woman presented to our institution after management closer to home for a peri-partum cardiomyopathy. The patient had a precipitous decline in end organ function and was transferred to our institution for urgent evaluation. Despite aggressive inotrope therapy that was initiated prior to her transfer, the patient continued to manifest deteriorating end organ function. After discussion with the patient's family about the implications of her clinical condition, she was taken to the cardiac catheterization laboratory for urgent implantation of the TandemHeart assist device. Our patients are managed under the combined care of cardiology and cardiac surgery, and decisions and implantation were undertaken as a joint effort. The patient had immediate improvement in perfusion manifest by normalization of renal function, preserved neurologic function and weaning of inotrope therapy. Flows were maintained at 3–4 l/min throughout her course. Despite effective cardiac unloading, the patient had persistent left ventricular dysfunction, and failed subsequent circulatory support weaning attempted at five days of support. During this time the patient underwent an extensive work-up and was deemed a suitable candidate for cardiac transplantation. Limitations of percutaneous support include device reliability and patient immobility. The patient and family were approached about more definitive circulatory support and agreed to proceed with conversion of her device to a Thoratec (Pleasanton, CA) pneumatic LVAD.
The patient was taken to the operating room on her sixth day of percutaneous VAD support. The cannulation scheme for the TandemHeart has been described previously [1,2]. The pump and configuration of the cannulae are shown in Fig. 1. Pump outflow is returned through a percutaneous Bio-Medicus (Medtronic, Inc., Minneapolis, MN) femoral arterial cannula. Inflow to the pump is provided by a cannula inserted with fluoroscopic guidance via the femoral vein directed into the left atrium by septal puncture. The pump is capable of providing up to 4 l/min of flow [3]. As we prepared to convert the patient to more definitive support we speculated that the TandemHeart cannulae would be well suited to provide access for cardiopulmonary support. In the operating room, the patient was evaluated by transesophageal echocardiography. It was apparent that her left ventricular function would not tolerate weaning of circulatory support, even with appropriate loading conditions and the addition of inotrope support. The patient's right heart function appeared preserved. The pump cannulae were incorporated into the surgical field. Echocardiographic evaluation revealed no thrombus within the left heart. A median sternotomy was undertaken and exposure for VAD implantation was completed. The patient underwent complete systemic heparinization in anticipation of initiating cardiopulmonary bypass (CPB). Under echocardiographic guidance, the left atrial cannula was carefully withdrawn until the tip was identified in the inferior portion of the right atrium. The pump was turned off just prior to beginning these manipulations. In turn the cannulae were separated from the TandemHeart, and attached directly to the CPB circuit. The patient subsequently underwent institution of bypass and we were able to maintain flows of 4 l/min with complete decompression of the heart, and the patient underwent uncomplicated implant of the Thoratec VAD. The patient was weaned without difficulties from CPB after completion of the implant procedure. She had excellent VAD and hemodynamic parameters, and echocardiographic confirmation of appropriate left ventricular unloading by the Thoratec device. The cannulae were approached by open exposure of the femoral vessels at the time of protamine administration, and removed with uncomplicated repair of the femoral vessels. We believe that the size of the cannulae mandate an open approach to femoral vessel repair. Addtionally, this approach coupled with attention to detail at the time of percutaneous access of the femoral vessels at the time of implant has likely contributed to our avoidance of cannula-related complications.
The patient's post-operative course was uncomplicated and she was discharged to home where she now awaits a suitable donor for transplantation.
3. Discussion
Over the six months since acquiring this device at our institution, we have successfully supported to discharge all six patients treated with the TandemHeart. To date we have reserved this device for patients we believed to be candidates for short periods of support and anticipated weaning of circulatory assistance. This patient is one of several that we have supported in profound cardiogenic shock at the time of implant of the device. We have obtained maximal flow rates of 4.5 l/min. Despite our concerns about flow limitations, we have not been faced with incomplete heart decompression or inadequate systemic support with this device; though we concede that our series to date remains small.
The patient described is the first we have encountered that required transition to more definitive VAD support. Conversion from percutaneous to definitive support is certainly not complicated, and, we have made all efforts to streamline this process. We continue to utilize CPB for implantation of all long-term devices. The cannulation scheme that we describe facilitates initiation of CPB and rapid VAD conversion. The transition of the TandemHeart cannulae to a CPB circuit was straight forward, limited aortic manipulation, and eliminated the need for right atrial instrumentation. We had no difficulties with providing adequate CPB flows for our patient. Additionally, in the event of incomplete cardiac decompression, or the need for right atrial access, flow could certainly be augmented by incorporation of a small superior vena cava cannula into the circuit. Finally, the Bio-Medicus cannula utilized for percutaneous return is chosen at the discretion of the implanting physician. Cannula size should be considered at implant, to assure that arterial flow can be matched to the patient's size when our cannulation scheme is utilized. Growing experience with successful support of patients with the TandemHeart provides an additional option for patients with profound cardiac failure. An expanded group of circulatory assist devices allows matching the most suitable pump to individual patient needs. We believe the cannulation scheme described in this report is a small but unique step towards assuring the most efficient and safest utilization of this technology for these critically ill patients.
References
Kar B, Butkevich A, Civitello AB, Nawar MA, Walton B, Messner GN, Gregoric ID, Feldman J, Myers TJ, Gemmato C, Delgado RM III. Hemodynamic support with a percutaneous left ventricular assist device during stenting of an unprotected left main coronary artery. Tex Heart Inst J 2004; 31:84–86.
Vranckx P, Foley DP, de Feijter PJ, Vos J, Smits P, Serruys PW. Clinical introduction of the TandemHeart, a percutaneous left ventricular assist device, for circulatory support during high-risk percutaneous coronary intervention. Int J Cardiovasc Intervent 2003; 5:35–39.
Pitsis AA, Dardas P, Mezilis N, Nikoloudakis N, Filippatos G, Burkhoff D. Temporary assist device for postcardiotomy cardiac failure. Ann Thorac Surg 2004; 77:1431–1433.(Sanjay Mehta and Walter P)