Ann Thorac Surg 2005;80:1490-1492
© 2005 The Society of Thoracic Surgeons
Case report
CardioWest Total Artificial Heart in a Moribund Adolescent With Left Ventricular Thrombi
M. Cristina Smith, MD
a
,
Francisco A. Arabía, MD
a
,
*
,
Pei H. Tsau, MD
a
,
Richard G. Smith, MSEE
b
,
Raj K. Bose, MD
a
,
Daniel S. Woolley, MD
a
,
Birger E. Rhenman, MD
a
,
Gulshan K. Sethi, MD
a
,
Jack G. Copeland, MD
a
a University of Arizona Sarver Heart Center, Tucson, Arizona, USA
b University Medical Center Artificial Heart Program, Tucson, Arizona, USA
Accepted for publication April 20, 2004.
* Address reprint requests to Dr Arabía, University of Arizona Sarver Heart Center, PO Box 245071, Tucson, AZ85724-5071 (Email: arabia{at}u.arizona.edu).
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Abstract
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Bridge to transplant is a well-known strategy to enable patients with congestive heart failure to live until transplant. A 15-year-old boy with Beckers' muscular dystrophy and cardiomyopathy was accepted for heart transplantation. He suffered a cardiac arrest and was placed on extracorporeal membrane oxygenator. A paracorporeal biventricular assist device and a total artificial heart were considered for bridge to transplant. A CardioWest total artificial heart was chosen because of the patient's size. Multiple left ventricular thrombi were identified at the time of the ventriculectomy. The patient did well with the total artificial heart was transplanted and discharged home. The unknown presence of significant left ventricular thrombi raises the question of outcome with a paracorporeal ventricular assist device.
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Introduction
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| Dr Copeland discloses that he has a financial relationship with CardioWest, and Dr Smith discloses that he has a financial relationship with Syncardia.
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Use of assist devices to bridge patients to transplant is an indispensable tool in the world of end-stage heart failure. Each patient that is evaluated for transplant should also be evaluated for their potential need for a device as a bridge to transplant. The choice of device used to bridge patients to transplant can be highly variable and should be tailored to the patient.
A 15-year-old boy with Becker's muscular dystrophy and subsequent severe cardiomyopathy is presented. He was admitted to our institution for transplant evaluation after 3 to 4 weeks of worsening congestive heart failure. Chronic anticoagulation for his congestive heart failure had not been started by the referring physician as symptoms had presented in a relative short period of time. He required dobutamine to maintain adequate tissue perfusion. Aggressive diuresis was also instituted. Echocardiography demonstrated left ventricular and left atrial dilatation, severely depressed left ventricular function with an ejection fraction of 13% to 17%, moderate tricuspid valve and mitral valve insufficiency, no effusions, and no evidence of ventricular thrombus. Left ventricular end diastolic dimension was 82 mm. He was evaluated and accepted for heart transplantation.
The patient's condition continued to deteriorate with progressive shortness of breath and decrease urine output despite increasing inotropic support. The decision was made to place a pulmonary artery catheter in the cardiac catheterization laboratory. Before beginning the procedure, the patient suffered a witnessed cardiac arrest. Compressions and advanced cardiac life support protocol were instituted. Cardiac function could not be recovered, so the patient was placed on venoarterial extracorporeal membrane oxygenator by femoral cannulation.
The patient was hemodynamically stabilized on extracorporeal membrane oxygenator. He was allowed to awaken from sedation while on extracorporeal membrane oxygenator to evaluate neurologic function before making the decision to implant a device with the intention of bridge to transplant. Time from arrest to compressions was approximately 3 minutes, and time to cardiopulmonary support was approximately 22 minutes. The patient was found to be neurologically intact, and he was taken immediately to the operating room.
In the operating room a discussion was undertaken to determine the best device for this patient. Transesophageal echocardiogram in the operating room revealed hypocontractile ventricles and no thrombus. The devices considered were a biventricular paracorporeal system with biventricular cannulation or a total artificial heart. Factors that were considered included the patient size (weight, 90.5 kg, body surface area 2.15 m2), profound biventricular failure, and no evidence of thrombus on prior echocardiogram. Because of his size and severity of his condition, the decision was made to use the CardioWest [1] total artificial heart (TAH; SynCardia Systems Inc, Tucson, AZ) as a bridge to transplant. One of the benefits of this device with this specific case is that it does not have inflow conduits as other devices. Figure 1 shows a schematic of the TAH in place and how the prosthetic ventricles connect directly to the atria and the great vessels. Furthermore, this device provides the highest output of any device currently available.
After opening the sternum, a biventriculectomy was performed 1 cm distal to the atrioventricular groove. A significant number of moderate size thrombi that were unexpected were identified in the left ventricular cavity (Fig 2). The CardioWest TAH was then implanted without incident, providing flows of 7 to 8 L per minute. Time from initiation of extracorporeal membrane oxygenator to initiation of TAH support was 6.5 hours. The patient was extubated the next day. He was re-listed for heart transplantation United Network for Organ Sharing status 1A on postoperative day 17. He was transplanted on postoperative day 63 when a suitable donor became available. He was discharged home 2 weeks later. He had no complications while on the CardioWest TAH or after heart transplantation.
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Comment
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Becker's muscular dystrophy is a X-linked recessive inheritance disorder that manifests with progressive muscle wasting of the legs and pelvis, which is also associated with a loss of muscle mass. This occurs in approximately 3 to 6 in 100,000 male births, and in some cases it affects the myocardium resulting in a cardiomyopathy with biventricular failure.
The literature has shown the effectiveness of both ventricular assist devices and also TAHs as bridges for end-stage heart failure. Left ventricular assist devices, which were first implanted in 1986, are now used in many institutions routinely with 75% to 91% of patients surviving to discharge and 74% surviving to transplant [2, 3]. These devices have inherent risk factors including infection, thromboembolism, cerebrovascular accident, and hemorrhage [4, 5]. The CardioWest TAH also carries the same risks. However it is an effective device for patients in need of high flows for adequate tissue perfusion.
This case illustrates the presence of left ventricular thrombus despite cardiac imaging with current technology. More importantly, it makes the observer wonder what would have been the outcome if a different device was used (eg, for example a device that would have required cannulation of the left ventricular apex). An operator who implants a device that requires left atrial or ventricular cannulation would probably have missed the presence of the left ventricular thrombus. Embolic adverse events are well documented for all types of devices, especially neurologic events. These thromboembolic adverse events are usually attributed to: (1) low flow states or areas of flow stagnation within the device, (2) thrombogenic surfaces, (3) hypercoagulable states, (4) ineffective anticoagulation therapy, or (5) thrombus within the ventricular cavity. The later one is difficult to quantify with current technology. However, a thromboembolic event in this patient may not have been because of any of the first four reasons mentioned and just because of pre-existing thrombus that went undetected.
Cerebrovascular event rates are different for currently used devices. Incidence of such events have been reported to be 39% for the Novacor left ventricular assist device (World Heart; Novacor, Oakland, CA), 16% for the Thoratec HeartMate (Thoratec Corporation, Pleasanton, CA), and 24% for the Thoratec ventricular assist device (Thoratec Corporation) [6, 7]. The incidence for the CardioWest TAH has been reported to be 8% [8]. A possible explanation for this lower incidence as compared with other devices is that the CardioWest TAH eliminates the remaining hypocontractile, thrombogenic left ventricle.
The use of a left ventricular assist device could be considered, however the patient had almost no right ventricular function in the preoperative transesophageal echocardiogram shortly after the cardiac arrest. Furthermore, the use of a cardioplegic arrest with removal of the left ventricular apex with examination for thrombus before insertion of a potential left ventricular cannula may be misleading as no complete assurance can be obtain that all the thrombus has been removed.
This case demonstrates the successful outcome in a terminal patient who required placement of a TAH as a bridge to transplant. The bridge to transplant literature regarding the use in the pediatric population is increasing. Although this patient is placed in the pediatric group by age, he is an adult by size. It appears the outcome in this specific case could have been different with a different device. However, there are many devices available for bridge to transplant and the choice of an appropriate device needs to be individualized to the patient's needs to maximize the likelihood of a successful outcome.
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References
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- Arabia FA, Copeland JG, Pavie A, Smith RG. Implantation technique for the CardioWest total artificial heart Ann Thorac Surg 1999;68:698-704.[Abstract/Free Full Text]
- Kherani AR, Garrido MJ, Cheema FH, Naka Y, Oz MC. Nontransplant surgical options for congestive heart failure Congest Heart Fail 2003;9:17-24.[Medline]
- Sun MD, We P. Bridge to Transplantationthe Penn State experience. Ann Thorac Surg 1999;68:684-687.[Abstract/Free Full Text]
- Tagusari O, Kormos RL, Kawai A. Risk of left ventricular assist device J Heart Lung Transplant 1999;18:1111-1119.[Medline]
- Arabia FA, Copeland JG, Smith RG, et al. Infections with the CardioWest total artificial heart ASAIO J 1998;44:M336-M339.[Medline]
- Minami K, El-Banayosy A, Sezai A, et al. Morbidity and outcome after mechanical ventricular support using Thoratec, Novacor, and HeartMate for bridging to transplantation Artif Organs 2000;24:421-426.[Medline]
- Mehta S, Souza D, Boehmer J, et al. Comparison of Pierce-Donachy (PD) and TCI left ventricular assist systems as bridge to transplantationan institutional experience. ASAIO J 1999;45:148.
- Copeland JG, Smith RG, Arabia FA, et al. Comparison of the CardioWest total artificial heart, the Novacor left ventricular assist system and the Thoratec ventricular assist system in bridge to transplantation Ann Thorac Surg 2001;71:S92-S97.[Abstract/Free Full Text]
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Abstract
Introduction
