To evaluate differences in morphologic parameters of ventricular remodeling in tissue samples and echocardiograms obtained at left ventricular (LV) assist device (LVAD) implantation in patients who later had sufficient clinical improvement to undergo device explantation versus those who required prolonged continuous-flow (CF) LVAD support and subsequent orthotopic heart transplantation (OHT). We evaluated 25 CF-LVAD patients, 10 of whom had improved cardiac function allowing device removal and 15 of whom underwent long-term device support (>24 months) and subsequent OHT. In all cases, myocardial tissue samples were collected from the LV core obtained at device implantation. Computerized morphometry was used to evaluate fibrosis and hypertrophy, including the cytoplasmic and nuclear diameter. Echocardiographic and hemodynamic parameters at the time of LVAD implantation were correlated with the histopathologic findings. Ten patients (7 men, 3 women; age 30±10 years) had their LVAD (HeartMateII) explanted due to cardiac functional improvement. Fifteen patients (11 men, 4 women; age 46±15 years) underwent OHT after 33±8 months (range: 26-50 months) of CF-LVAD support (HeartMate II, 13 cases; HeartWare, 2 cases). Four patients had ischemic cardiomyopathy, and 11 had nonischemic disease. At LVAD implantation, the LV core from the explant group showed a smaller myocyte diameter (24.55±4.63 vs. 37.09±10.22µ; P=0.0003), a smaller nuclear diameter (12.21±1.72 vs. 15.65±3.88µ; P=0.003), and less fibrosis (10.24±4.03% vs. 17.5±10.36%; P=0.014) than were observed in the transplant group. The left ventricular end-diastolic diameter (LVEDD) was smaller in the explant group than in the transplant group (6.37±0.63 vs. 7.18±1.11 cm; P=0.017). Patients with clinical improvement allowing LVAD explantation had less hypertrophy, less fibrosis, and a smaller LVEDD at the time of LVAD implantation than did patients who required prolonged LVAD support and subsequent OHT. These findings suggest that less extensive morphologic ventricular remodeling changes at LVAD implantation may help determine which subset of patients may have a potential for myocardial reconditioning.

Left ventricular assist device (LVAD) support is emerging as both an alternative and bridge to orthotopic heart transplantation in end-stage heart failure. Possibility of myocardial recovery with potential LVAD explantation is one of the unique advantages of LVAD support. Paucity of reliable indicators of successful LVAD weaning remains an issue in patient selection and donor organ allocation. We analyze whether native left ventricular cardiac power output (CPO) is a reliable indicator of myocardial recovery for potential LVAD explantation.

Pseudoaneurysm of the ascending aorta is a rare but severe complication of cardiac surgery. Most cases occur after coronary artery bypass grafting (CABG) and aortic valvular procedures, and many others occur after cardiac transplantation. Thus far, the only reported case of a pseudoaneurysm related to a left ventricular assist device (LVAD) is a pseudoaneurysm related to the prosthetic graft itself.1Knosalla C. Weng Y. Buz S. Loebe M. Hetzer R. Pseudoaneurysm of the outflow graft in a patient with Novacor N100 LVAS system.Ann Thorac Surg. 2000; 70: 1594-1596Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar We report here the first case of a pseudoaneurysm related to LVAD explantation. In December 1999, a 47-year-old woman with a history of progressive dyspnea on exertion presented with a syncopal episode. She was admitted to a local hospital, where congestive heart failure was diagnosed. Echocardiography revealed an ejection fraction of 10%. The patient was transferred to St Luke's Episcopal Hospital for further evaluation and treatment. There she underwent placement of an intra-aortic balloon pump, followed by simultaneous implantation of an LVAD (Thoratec VAD; Thoratec Corporation, Pleasanton, Calif) and performance of the Batista procedure. Three months later, in February 2000, the patient's condition had improved to the point that the LVAD could be removed. Immediately after its removal, the patient experienced postoperative bleeding that required mediastinal exploration to control. The patient's sternum was closed 1 day later. The patient did well for almost 1 year, until she complained of a painful swelling of the upper sternum. A computed tomography (CT) scan of the chest showed fluid anterior and posterior to the sternum extending back to the margin of the ascending thoracic aorta, a finding compatible with an abscess. The abscess was incised and drained after achievement of local anesthesia. A culture grown from a sample of the fluid grew methicillin-resistant Staphylococcus aureus. Intravenous vancomycin was instituted for 1 month. On follow-up examination, a repeat CT scan showed a 2.3-cm−diameter saccular aneurysm involving the distal ascending thoracic aorta and a parasternal collection of fluid containing air suggestive of an abscess. The abscess was surgically drained, and intravenous vancomycin was continued at a dosage of 0.5 g/d. Again, a culture grown from a sample of the drained fluid grew methicillin-resistant S aureus. Magnetic resonance angiography (MRA) was performed to confirm the diagnosis of aneurysm of the ascending aorta. This revealed a pseudoaneurysm of the ascending aorta measuring 2.0 × 2.4 × 3.0 cm (Figure 1). Consequently, the patient was scheduled for resection of the pseudoaneurysm. The femoral vessels were exposed and readied for cannulation, and the sternum was opened with an oscillating saw. Because the pseudoaneurysm was adherent to the sternum, the opening of the sternum caused inadvertent entry into the pseudoaneurysm. The femoral vessels were immediately cannulated, and femorofemoral bypass was commenced. The patient was cooled to 18°C, and circulatory arrest combined with retrograde cerebral perfusion was initiated. Then the sternum was slowly opened. After reduction of the blood flow to 500 mL/min, the patient was placed in the Trendelenburg position to prevent air embolism. The pseudoaneurysm, together with the remnant of the prosthetic graft still attached to the ascending aorta, was resected. The pre-existing anastomosis between the prosthetic graft and the ascending aorta was found to be disrupted for about one third of its entire circumference. The disrupted portion of the anastomosis was resected, leaving a 3 × 2–cm defect at the aorta, and further dissection of the ascending aorta was done to facilitate crossclamping. After crossclamping, the patient was warmed to 32°C and then subjected to retrograde cerebral perfusion. The defect at the aorta was repaired by using an oval Dacron patch. The crossclamp was then released, and the patient was warmed to 37°C and weaned off cardiopulmonary bypass. The sternum was left open until the next day, when the patient was brought back to the surgical theater for placement of an omental graft and closure of the sternum. Even though cultures of the resected pseudoaneurysm specimen did not grow any organisms, an antibiotic therapy regimen was instituted. Postoperatively, the patient remained stable and was discharged home after 2 weeks. At 1 year of follow-up, the patient was stable with no neurologic deficits. A CT scan of the chest showed normal findings and confirmed that the Dacron patch repair was still intact (Figure 2). The antibiotic regimen was discontinued on the recommendation of an infectious disease consultant. This report documents the first case of a pseudoaneurysm related to the removal of an LVAD. CT scanning and MRA confirmed the diagnosis, and surgical intervention was performed to correct the problem. Although cardiac transplantation is the therapeutic option of choice and currently the most frequent treatment for end-stage heart failure, wider use of this approach has been limited by several issues. These include fewer available donor hearts than transplant candidates and the resultant long waiting period for an organ. In addition, there are the usual problems of rejection faced by all transplant recipients and the heart-specific problem of coronary graft atherosclerosis, which can significantly limit the long-term survival of heart recipients.2Frazier O.H. Mechanical cardiac assistance historical perspectives.Semin Thorac Cardiovasc Surg. 2000; 12: 207-220PubMed Scopus (24) Google Scholar During the past 2 decades, temporary mechanical circulatory support has become a widely accepted option for patients with intractable heart failure, particularly those awaiting cardiac transplantation. An unexpected benefit of prolonged LVAD use has been improved ventricular function in patients with idiopathic and dilated cardiomyopathies. In a few cases in which LVAD removal was necessitated by device failure or device-related infection, the patient's native cardiac function had recovered sufficiently to avoid subsequent transplantation or reimplantation of an assist device.3Frazier O.H. Future direction of cardiac assistance.Semin Thorac Cardiovasc Surg. 2000; 12: 251-258PubMed Scopus (8) Google Scholar Prolonged mechanical unloading of the failing heart by an LVAD promotes ventricular recovery (ie, improved cardiothoracic ratio, end-diastolic dimension, ejection fraction, pulmonary capillary wedge pressure, and pulmonary vascular resistance and also striking histologic improvement of the myocardium).4Frazier O.H. Benedict C.R. Radovancevic B. Bick R.J. Capek P. Springer W.E. et al.Improved left ventricular function after chronic left ventricular unloading.Ann Thorac Surg. 1996; 62: 675-682Abstract Full Text Full Text PDF PubMed Scopus (301) Google Scholar, 5Hetzer R. Muller J.H. Weng Y. Meyer R. Dandel M. Bridging-to-recovery.Ann Thorac Surg. 2001; 71: S109-113Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar This unexpected benefit of prolonged LVAD use has led to another indication for LVAD support: bridging to recovery. Although this new use of an LVAD is promising, this case demonstrates that the device might also lead to unexpected complications, such as the development of a pseudoaneurysm. Typically, pseudoaneurysm of the ascending aorta is thought to be an unusual and potentially fatal complication of cardiovascular surgery. Most pseudoaneurysms are associated with aortic valve or CABG surgery and are often infectious in origin. In several reported series, infected pseudoaneurysms occurred along the aortic suture lines after cardiac transplantation. However, to our knowledge, there has never been any report of a case of an infected pseudoaneurysm of the prosthetic graft remnant that remains attached to the ascending aorta after LVAD removal. The only similar report in the literature is of a pseudoaneurysm of the outflow graft itself in a patient supported with a Novacor N100 left ventricular assist system (Baxter Healthcare Corp, Oakland, Calif).1Knosalla C. Weng Y. Buz S. Loebe M. Hetzer R. Pseudoaneurysm of the outflow graft in a patient with Novacor N100 LVAS system.Ann Thorac Surg. 2000; 70: 1594-1596Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar Because the ascending aorta has been the preferred site for arterial cannulation for primary heart operations for the past 2 decades, and because the number of CABG and aortic valvular procedures involving entry into the ascending aorta has increased, pseudoaneurysms of the thoracic aorta have become more frequent.6Sullivan K.L. Steiner R.M. Smullens S.N. Griska L. Meister S.G. Pseudoaneurysm of the ascending aorta following cardiac surgery.Chest. 1988; 92: 138-143Crossref Scopus (157) Google Scholar, 7Razzouk A. Gundry S. Wang N. Heyner R. Sciolaro C. Van Arsdell G. et al.Pseudoaneurysms of the aorta after cardiac surgery of chest trauma.Am Surg. 1993; 59: 818-823PubMed Google Scholar Predisposing factors include graft infection, dissected native aorta, and possibly tissue necrosis after excessive use of biologic glue.8Katsumata T. Moorjani N. Vaccari G. Westaby S. Mediastinal false aneurysm after thoracic aortic surgery.Ann Thorac Surg. 2000; 70: 547-552Abstract Full Text Full Text PDF PubMed Scopus (123) Google Scholar Pseudoaneurysms are the result of disruption of at least one layer of the vessel wall and are contained by the remaining vascular layers or the surrounding structures of the mediastinum with or without development of a neointima. In this respect, pseudoaneurysms differ from true aneurysms, in which all 3 vascular layers remain intact.9Marx M. Gardiner G.A. Miller R.H. The truth about false aneurysm.Am J Radiol. 1985; 145: 193-194Google Scholar Although this pseudoaneurysm was the result of an infection and breakdown of the anastomotic graft stump, we were able to repair the defect with a prosthetic patch, with no untoward effects.10Jacobs M.J. Reul G.J. Gregoric I. Cooley D.A. In-situ replacement and extra-anatomic bypass for the treatment of infected abdominal grafts.Eur J Vasc Surg. 1991; 5: 83-86Abstract Full Text PDF PubMed Scopus (81) Google Scholar As the present case makes clear, follow-up is essential for LVAD-supported patients who undergo device removal and are left with a remnant of the prosthetic graft attached to the ascending aorta because the remnant has the potential to become a focus of infection or to develop into a pseudoaneurysm. In cases of mediastinal infection in this subgroup of patients, early MRA should be done because it might easily reveal the presence of a pseudoaneurysm. Surgical management is essential in the setting of pseudoaneurysms after LVAD explantation.

Infection is a problem in patients undergoing support with left ventricular assist systems. To better understand the nature of this problem, we retrospectively analyzed data on 56 patients supported by the HeartMate (Thermo Cardiosystems, Inc, Woburn, MA) left ventricular assist system. Infection was defined as fever > 38 degrees C, white blood count > 12,000 cells/ml, and a need for antimicrobial therapy. Of the 56 patients, 25 (41%) had an infection. Device related infections (as determined by positive culture from driveline, housing, or inflow or outflow tract) occurred in eight patients (14.3%). The most common sites of infection were the respiratory system (42.4%), the central venous catheter (27.8%), and blood (18.3%). Of the positive cultures, 84% were bacterial and 16% fungal. There were no positive viral cultures. Positive cultures from left ventricular assist system related sites made up only 8.7% of the total. All but one of the patients with device related infections survived to transplantation. The long-term survival rate for patients in this group after transplantation was 77.8%. Two patients required surgical revision of the driveline because of infection. Both were free of infection postoperatively. Patients who stayed in the intensive care unit for longer periods had a greater risk of infection (uninfected, 35 days; infected, 78 days). In conclusion, although infection is a problem in patients undergoing support with left ventricular assist systems, it does not preclude survival to transplantation or alter the survival rate after transplantation.

Left ventricular assist devices (LVAD) are used increasingly as bridges to cardiac transplantation. The typical LVAD candidate is a bedridden, critically ill, New York Heart Association (NYHA) Class IV patient with congestive heart failure (CHF) who is dependent upon intravenous, inotropic, and, in many cases, intra-aortic balloon support. The LVAD provides the potential for pre transplant rehabilitation by allowing the patient to become ambulatory, and by improving muscle tone, muscle mass, and nutritional status before transplantation. However, whether the abnormal exercise capacity of these patients improves after implantation has not been elucidated. The purpose of the present study was to evaluate the exercise capacity of patients with CHF after LVAD implantation (n = 10) using peak oxygen consumption during maximal exercise (MVO2), and comparing the results with those of a group of NYHA Class III patients with CHF (n = 14). After 2 months of implantation, MVO2 of the patients with LVAD was 12.8 +/- 0.3 ml/kg/min, which was comparable to that of the NYHA Class III patients with CHF (12.5 +/- 0.5 ml/kg/min). Four of 10 patients with LVAD were monitored for more than 5 months when MVO2 rose to 15.4 +/- 1.0 ml/kg/min (p < 0.05 vs NYHA Class III). In conclusion, the exercise capacity of patients with LVAD recovers slowly but significantly after 5 months of implantation, promising the potential for complete recovery from heart failure in patients supported with an LVAD.

Nishimura, M.; Radovancevic, B.; Odegaard, P.; Myers, T.; Springer, W.; Macris, M. P.; Frazier, O. H. Author Information