Ann Thorac Surg 2008;85:1646-1649. doi:10.1016/j.athoracsur.2008.01.020
© 2008 The Society of Thoracic Surgeons
Original Articles: Adult Cardiac
Clinical Experience With Sternotomy Versus Subcostal Approach for Exchange of the HeartMate XVE to the HeartMate II Ventricular Assist Device
Igor D. Gregoric, MDa,*,
Brian A. Bruckner, MDa,
Leon Jacob, MDa,
Biswajit Kar, MDb,
William E. Cohn, MDa,
Saverio La Francesca, MDa,
O.H. Frazier, MD
a Division of Cardiopulmonary Transplantation, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
b Heart Failure Clinic, Texas Heart Institute at St. Luke's Episcopal Hospital, Houston, Texas
Accepted for publication January 9, 2008.
* Address correspondence to Dr Gregoric, Texas Heart Institute, MC 3-147, PO Box 20345, Houston, TX 77225-0345 (Email: epongratz{at}heart.thi.tmc.edu).
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Abstract
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Background: Most patients undergoing destination therapy with a HeartMate XVE left ventricular assist device will eventually require pump exchange to continue long-term cardiac support.
Methods: To determine whether left ventricular assist device exchange can be accomplished with low morbidity and mortality, we retrospectively reviewed the records of 14 patients who experienced pump malfunction and subsequently required replacement of their HeartMate XVE left ventricular assist devices with HeartMate II axial-flow pumps. We collected data regarding duration of support and reasons for pump failure, perioperative characteristics, and operative approach.
Results: On average, patients were supported 473 ± 233 days with HeartMate XVE pumps. Seven early patients required both subcostal and sternotomy incisions; 7 later patients had subcostal incisions only. Thirteen patients underwent successful exchange to the HeartMate II; 1 patient died in the operating room. Another patient died in the perioperative period (30-day mortality, 14% [2 of 14]). There were significant differences between the two groups. The patients who required only subcostal incisions had shorter operative times (187 versus 220 minutes; p = 0.04) and required fewer transfused blood products (packed red blood cells, 8.6 versus 28.7 units; p = 0.03; and fresh-frozen plasma, 12.4 versus 30.9 units; p = 0.04). Additionally, the patients with subcostal incisions had shorter postoperative intensive care unit stays (5.3 ± 1.1 versus 8.4 ± 3.1 days for redo sternotomy patients; p = 0.03). Of the survivors, average hospital stay was 22 ± 14 days. Average long-term follow-up was 11.2 ± 7.8 months; 71% (10 of 14) of patients are currently alive.
Conclusions: Exchange of a HeartMate XVE to a HeartMate II can be accomplished with relatively low morbidity and mortality through a subcostal approach.
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Introduction
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With the continued shortage of donor hearts, the need has increased for mechanical circulatory support devices both as bridges to transplant and as destination therapy in patients with severe heart failure. Twenty years ago left ventricular assist device (LVAD) support was generally limited to a few centers, and the average support time was approximately 3 months for bridge to cardiac transplantation [1]. The HeartMate I, XV, and XVE devices (Thoratec Corporation, Pleasanton, CA) are the most widely implanted LVADs in the world; more than 4,000 such pumps have been implanted worldwide [2]. Although technologic advances have improved the durability of the HeartMate XVE over its predecessors (3% failure rate at 6 months; 18% failure rate at 1 year) [2, 3], device malfunction is still a problem, especially after 1 year of HeartMate XVE support [2]. Therefore, development of a durable assist device capable of long-term support with minimal complications remains a goal for extending the lives of patients with severe heart failure. The HeartMate II LVAD, which is nearing the end of clinical trials, is an axial-flow pump that shows great promise for long-term cardiac support [4–7]. Herein we report our experience with 14 patients who underwent device exchange to a HeartMate II device after HeartMate XVE pump malfunction. The clinical outcomes as well as the surgical technique for pump exchange are reported.
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Material and Methods
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Patient Characteristics
We retrospectively reviewed the hospital records of 14 patients who underwent exchange of a HeartMate XVE to a HeartMate II device between June 2005 and May 2007. All patients had diagnoses of ischemic or dilated cardiomyopathy and were being supported by a HeartMate XVE at the time of admission for the exchange procedure. Demographic and clinical data were recorded and included age, sex, duration of HeartMate XVE support, operative times, transfusion of packed red blood cells and fresh-frozen plasma, and reasons for pump failure and subsequent exchange to HeartMate II. We also recorded the type of operative procedure, intensive care unit length of stay after the exchange operation, and significant complications during hospitalization (up to 30 days). Long-term follow-up was available for all patients. The study was approved by the institutional review board, and all patients gave informed consent.
Pump Exchange Technique
Whenever possible, patients' coagulation factors were corrected preoperatively with fresh-frozen plasma, vitamin K, platelets, or cryoprecipitate. In addition, they underwent a thorough workup, including an echocardiogram and right heart cardiac catheterization. Depending on the findings of these studies, inotropic agents or pulmonary vasodilators were started before the exchange operation. Additionally, cross-matched blood products were readily available in the operating room. To optimize the coagulation profile, the bypass pump circuit was primed with fresh-frozen plasma.
All patients underwent femoral artery and femoral vein exposure for cannulation for cardiopulmonary bypass. During the entire cardiopulmonary bypass time, the patients were minimally ventilated (200 mL tidal volume, 10 breaths/min) in an effort to optimize pulmonary function and minimize pulmonary vascular resistance. All patients had a left subcostal incision to expose the HeartMate XVE device. Extension of the incision to the right subcostal area was patient-specific and was determined based on factors such as body habitus, exposure of the outlet graft, and the presence of infection. If there was no device infection, a left subcostal incision with slight extension across the midline (similar to a Chevron incision, but smaller) was typically performed (Fig 1). The initial patients had their devices explanted and pump placement done through a median sternotomy approach. The more recent and currently preferred approach, however, is through an extended left subcostal incision with detachment of the rectus muscle.
Subcostal Approach (After Exposure)
The HeartMate XVE, including the apical sewing ring and the outflow graft, was exposed. A small segment of the outflow graft was then exposed at its course under the right subcostal sternal area. With the patient in Trendelenburg position and partial cardiopulmonary bypass initiated, the driveline was cut. Two clamps were placed side-by-side on the proximal segment of the outflow graft, and the graft was incised between the two clamps. Next, the plastic band around the inflow cannula and sewing ring cuff was removed. The inflow cannula and pump were carefully removed from the sewing ring cuff, and the HeartMate II inflow cannula was placed within the cuff. To minimize blood loss and to avoid air embolism, the heart was fibrillated or cardiac motion was minimized pharmacologically (esmolol or adenosine with dipyridamole). Maximal flow was achieved by suction on a multiple-holed venous cannula placed from the femoral vein to the right atrium. After the inflow cannula was secured to the apical cuff with a plastic band, a vent catheter was connected to the HeartMate II vent port to assist in the procedure of removing air. The heart was defibrillated, if necessary, and cardiac activity was restored. The new outflow graft was then sewn to the old polyethylene terephthalate fiber (Dacron, Dupont Corp, Wilmington, DE) outflow graft of the HeartMate XVE pump at the costal margin. After the outflow graft anastomosis was completed, with the patient still in Trendelenburg position, the outflow graft was attached to the HeartMate II pump. Cardiopulmonary bypass flow was reduced to 40 mL · kg–1
· min–1 to allow the heart to fill with blood, and full ventilation was resumed. Transesophageal echocardiography was used to monitor the entire procedure of removing air. When the air removal was complete, the clamp was removed from the outflow graft, and LVAD flow was initiated. Transesophageal echocardiography was also used to assess adequacy of flow rates and degree of ventricular unloading.
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Results
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Fourteen patients who previously had a HeartMate XVE device implanted underwent exchange to a HeartMate II axial-flow pump. The study group included 13 men and 1 woman whose average age was 46 ± 17 years (range, 17 to 77 years; Table 1). The average length of HeartMate XVE support was 473 ± 233 days (range, 90 to 870 days), and the most common reason for pump exchange was primary motor or bearing failure (10 patients). In addition, 1 patient experienced inflow valve incompetence; 1 had inflow cannula malposition or kinking; 1 had an infection in the LVAD pocket and device malfunction; and 1 had transient ischemic attacks secondary to thrombus on the inflow valve, necessitating device removal [8].
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Table 1 Clinical Experience With HeartMate XVE to HeartMate II Left Ventricular Assist Device Exchange (as of May 1, 2007)
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All patients received optimal medical treatment before operation with appropriate inotropic agents and with transfused fresh-frozen plasma or platelets, as indicated. In general, patients received blood products before operation if they were anemic or thrombocytopenic, or had abnormal laboratory coagulation studies (prothrombin time, partial thromboplastin time, international normalized ratio). In 50% of the patients (n = 7), successful device exchange was performed through a subcostal incision only (Table 1). If needed, the incision was extended slightly to allow more exposure of the outflow graft. The other half of the patients (n = 7) had subcostal and sternotomy incisions. Owing to extensive adhesions and coagulopathy, all of the patients who had a redo sternotomy underwent only skin closure, with subsequent mediastinal exploration, evacuation of blood, and sternal closure the following day. There were significant differences in the operative times between the patients who had only subcostal incisions (187 ± 63 minutes) and those who had a median sternotomy (220 ± 126 minutes; p = 0.04; Table 2). In addition, the group who had subcostal incisions required fewer transfusions of packed red blood cells (8.6 ± 4.5 units) than the group who had median sternotomies (28.7 ± 18 units; p = 0.03). The subcostal group also required less fresh-frozen plasma (12.4 ± 21 units) than the median sternotomy group (30.9 ± 9.9 units; p = 0.04).
Of the 14 patients, 2 (14%) died perioperatively: 1 died in the operating room after pump exchange secondary to coagulopathy and massive hemorrhage; the other died immediately after surgery as a result of profound coagulopathy and bleeding. For the 12 patients (86%) who survived the operation, the length of hospital stay ranged from 13 to 62 days (average, 22 ± 14 days). Total length of stay was prolonged by the need to use the discharge protocol required by the US Food and Drug Administration. Intensive care unit stay was shorter for the patients who had subcostal incisions than for the patients who underwent redo sternotomies (5.3 ± 1.1 versus 8.4 ± 3.1 days; p = 0.03). Six patients had major postoperative complications, including deep venous thrombosis (n = 1), acute renal failure (n = 1), mediastinitis (n = 1), and pancreatitis (n = 1) (Table 1), but all resolved with medical treatment. Two patients had cerebrovascular accidents with subsequent mild, long-term functional impairment; both were eventually able to adequately handle activities of daily living. Only one of these patients sustained a large air embolus during the pump dissection and was treated by deep hypothermic arrest and retrograde cerebral perfusion, followed by barbiturate coma [9]. Both of these patients needed tracheostomies for respiratory failure, but both were weaned successfully from ventilatory support. However, none of the 14 patients suffered adverse events or air emboli during the actual pump exchange portion of the procedure.
The average long-term follow-up period was 11.2 ± 7.8 months; 71% (10 of 14) of patients were alive as of May 1, 2007. Two patients died late: 1 patient died after subsequent heart transplantation, and 1 patient died of unknown causes at an outside hospital.
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Comment
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We found that exchange of a HeartMate XVE LVAD to the newer HeartMate II axial-flow pump can be accomplished with less morbidity and mortality. The subcostal approach we described simplifies the successful exchange of these devices. In our opinion, a median sternotomy approach is seldom required for the exchange.
Axial-flow LVADs are smaller, more reliable, and more durable than the current pulsatile pumps, such as the HeartMate XVE, making them useful for a broader patient population. Malfunction of the HeartMate XVE is not uncommon and can result in significant morbidity and mortality [10, 11]. The most common malfunctions are primary pump motor or bearing failures, driveline malfunction or infections, and inflow valve incompetence [12, 13]. We now always replace failed HeartMate XVEs with axial-flow pumps. In the 2 years of our series, 14 patients required pump exchange. In contrast, during our clinical trial of the HeartMate II, we have had to replace the pump in 2 of 57 patients, but both of these replacements were secondary to trauma; 1 patient had a driveline fracture from a fall; the other patient fell off a skateboard and damaged the primary motor or impeller of the pump [14].
Reoperative surgery in these patients can be challenging, especially in the scenario of pump failure requiring urgent device exchange. In our early experience with HeartMate XVE exchange, we performed redo sternotomies to optimally expose the outflow graft. As we gained experience with the exchange procedure, however, we learned that we could expose enough of the pump and graft with a left subcostal incision extended slightly past the midline. With this smaller incision, only the most proximal aspect of the outflow graft is exposed during the dissection. However, after the pump is removed from the apical cuff, gentle traction can be applied on the outflow graft; usually it will give, and several more centimeters will then be available for the clamp and anastomosis to the HeartMate II graft. Because the HeartMate XVE outflow graft is 20 mm in diameter, whereas the HeartMate II graft is 16 mm in diameter, dissection must be sufficient to allow for clamping and enough "cuff" to perform the tailored graft-to-graft anastomosis.
All patients undergoing device exchange will exhibit a coagulopathy, hence the need for temporary chest and incision closure with the mediastinal approach. In our series, most patients underwent staged operations with mediastinal exploration, irrigation, and definitive closure the following day. To allow the clotting cascade to normalize, further staging of these operations might be considered for stable patients awaiting pump exchange, ie, dissection of the pump and outflow graft the first day, followed by pump exchange the next day [15]. Because it appears that the HeartMate XVE has a limited life span, at the first sign of pump malfunction, elective exchange to the axial-flow HeartMate II should be considered. Mechanical bearing failures have not occurred in the HeartMate pumps to date.
In summary, exchange of a HeartMate XVE pump to a HeartMate II axial-flow pump can be accomplished with relatively low morbidity and mortality, despite the need for reoperation. The technique we described simplifies the successful exchange of these devices, and, in most cases, does not require a redo sternotomy incision.
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Acknowledgments
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The authors wish to acknowledge Sadik Sharek, MD, and Timothy J. Myers, BS, for help in data collection; Pranav Loyalka, MD, for care of the patients in this study; and Marianne Mallia, ELS, for editorial assistance in the preparation of the manuscript.
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References
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- Frazier OH, Duncan JM, Radovancevic B, et al. Successful bridge to heart transplantation with a new left ventricular assist device J Heart Lung Transplant 1992;11:530-537.[Medline]
- Martin J, Friesewinkel O, Benk C, Sorg S, Schultz S, Beyersdorf F. Improved durability of the HeartMate XVE left ventricular assist device provides safe mechanical support up to 1 year but is associated with high risk of device failure in the second year J Heart Lung Transplant 2006;25:384-390.[Medline]
- Dowling RD, Park SJ, Pagani FD, et al. HeartMate VE LVAS design enhancements and its impact on device reliability Eur J Cardiothorac Surg 2004;25:958-963.[Abstract/Free Full Text]
- Burke DJ, Burke E, Parsaie F, et al. The Heartmate II: design and development of a fully sealed axial flow left ventricular assist system Artif Organs 2001;25:380-385.[Medline]
- Delgado R, Bergheim M. HeartMate II left ventricular assist device: a new device for advanced heart failure Expert Rev Med Devices 2005;2:529-532.[Medline]
- Frazier OH, Delgado III RM, Kar B, Patel V, Gregoric ID, Myers TJ. First clinical use of the redesigned HeartMate II left ventricular assist system in the United States: a case report Tex Heart Inst J 2004;31:157-159.[Medline]
- Griffith BP, Kormos RL, Borovetz HS, et al. HeartMate II left ventricular assist system: from concept to first clinical use Ann Thorac Surg 2001;71(Suppl):S116-S120.[Medline]
- Frazier OH, Forrester, MD, Gemmato C, Gregoric ID. Urgent pump exchange for stroke resulting from a distorted HeartMate XVE inflow conduit J Heart Lung Transplant 2007;26:646-648.[Medline]
- Gregoric ID, Myers TJ, Kar B, et al. Management of air embolism during HeartMate XVE exchange Tex Heart Inst J 2007;34:19-22.[Medline]
- Birks EJ, Tansley PD, Yacoub MH, et al. Incidence and clinical management of life-threatening left ventricular assist device failure J Heart Lung Transplant 2004;23:964-969.[Medline]
- Rose EA, Gelijns AC, Moskowitz AJ, et al. Long-term mechanical left ventricular assistance for end-stage heart failure N Engl J Med 2001;345:1435-1443.[Medline]
- Myers TJ, McGee MG, Zeluff BJ, Radovancevic B, Frazier OH. Frequency and significance of infections in patients receiving prolonged LVAD support ASAIO Trans 1991;37:M283-M285.[Medline]
- Myers TJ, Palanichamy N, La Francesca S, Odegaard PA, Gregoric ID, Frazier OH. Management of multiple left ventricular assist device failures in a patient J Heart Lung Transplant 2007;26:98-100.[Medline]
- La Francesca S, Smith R, Gregoric ID, et al. Replacement of a malfunctioning HeartMate II left ventricular assist device in a 14-year-old after a sudden fall J Heart Lung Transplant 2006;25:862-864.[Medline]
- Cohn W, Gregoric ID, Frazier OH. Staged reoperation: a novel strategy for high-risk patients Ann Thorac Surg 2007;83:1558-1559.[Abstract/Free Full Text]
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Abstract
Introduction
