Cardiac resynchronization therapy and outcomes in patients with left ventricular assist devices: a systematic review and meta-analysis.

The impact of cardiac resynchronization therapy (CRT) on clinical outcome in patients with a continuous-flow left ventricular assist device (LVAD) is currently not well understood. We conducted a systematic literature review and meta-analysis with an intention to summarize all published clinical evidence. We searched MEDLINE and EMBASE databases through March 2018 for studies that compared the outcomes in patients with LVAD and CRT. Pooled odds ratios (OR) and 95% confidence intervals (CI) were calculated using a random-effects model, inverse variance method. The between-study heterogeneity was assessed using the Q statistic and I2. A total of seven studies that included 1157 (575 CRT; 582 non-CRT) patients were identified. Our meta-analysis did not demonstrate a significant difference in the risk of mortality (pooled OR = 1.21, 95% CI 0.90-1.63, P = 0.21), ventricular arrhythmia incidence (pooled OR = 1.36, 95% CI 0.99-1.86, P = 0.06), hospitalization (pooled OR = 1.36, 95% CI 0.59-3.14, P = 0.48), or implantable cardioverter defibrillator therapies (pooled OR = 1.08, 95% CI 0.51-2.30, P = 0.84) among the CRT group compared with the non-CRT group. There was high heterogeneity with an I2 of 75% for ICD therapies. Among LVAD patients, CRT combined did not significantly affect mortality, re-hospitalization, ventricular arrhythmia incidence, and ICD therapies.

Extracorporeal Support During Bilateral Sequential Lung Transplantation in Patients With Pulmonary Hypertension: Risk Factors and Outcomes.

OBJECTIVE: To identify preoperative predictors of extracorporeal support in patients with pulmonary hypertension (PH) undergoing bilateral sequential lung transplantation (LTx), and to examine outcomes associated with the use of extracorporeal support. DESIGN: Retrospective, observational study. SETTING: Single organ transplantation and tertiary care university medical center. PARTICIPANTS: Adults with PH (preoperative mean pulmonary artery pressure (mPAP)≥25 mmHg) who underwent primary bilateral sequential LTx during 2007 to 2013. MEASUREMENTS AND MAIN RESULTS: Of 262 patients with PH undergoing LTx, extracorporeal support was initiated intraoperatively in 149 (57%). Preoperative severe right ventricle (RV) dysfunction and moderate or severe tricuspid regurgitation (TR) were associated with extracorporeal support. In the remaining 208 patients without those factors, increasing preoperative oxygen requirement (odds ratio [OR] 1.30 per 1 L/min, 95% confidence intervals [CI] 1.11-1.52, p = 0.001), presence of RV dilation (OR 2.77, 95% CI 1.28-6.02, p = 0.010), and mPAP (OR 1.33 per 5-mmHg increase in mPAP, 95% CI 1.04-1.70, p = 0.021) were associated independently with extracorporeal support in the multivariable model. Analysis of 49 propensity-matched pairs showed longer intensive care unit (5 v 14 days, p = 0.006) and hospital stays (27 v 39 days, p = 0.016) and increased need for tracheostomy (16% v 41%, p = 0.017) in patients exposed to extracorporeal support but no differences in 30-day mortality, stroke, myocardial infarction, or dialysis. CONCLUSIONS: Severity of RV dysfunction, TR, RV dilatation, increasing oxygen requirement, and increasing mPAP showed significant associations with the need for extracorporeal support during LTX in patients with PH. Extracorporeal support was associated with increased length of stay and tracheostomy but not with mortality or other complications. © 2016 Elsevier Inc. All rights reserved.

Further evidence for sustained systemic inflammation in xenograft recipients (SIXR).

INTRODUCTION: In pig-to-baboon heart/artery patch transplantation models, adequate costimulation blockade prevents a T-cell response. After heart transplantation, coagulation dysfunction (thrombocytopenia, reduced fibrinogen, increased D-dimer) and inflammation (increased C-reactive protein [CRP]) develop. We evaluated whether coagulation dysfunction and/or inflammation can be detected following pig artery patch transplantation. METHODS: Baboons received heart (n = 8) or artery patch (n = 16) transplants from genetically engineered pigs and a costimulation blockade-based regimen. Heart grafts functioned for 15-130 days. Artery recipients were euthanized after 28-84 days. Platelet counts, fibrinogen, D-dimer, and CRP were measured. RESULTS: Thrombocytopenia and reduced fibrinogen developed only in recipients of hearts not expressing a coagulation-regulatory protein (n = 4), but not in other heart or patch recipients. However, in heart recipients (n = 8), there were sustained increases in D-dimer (<0.5 to 1.9 ug/ml [P < 0.01]) and CRP (0.26-2.2 mg/dl [P < 0.01]). In recipients of artery patches, there were also sustained increases in D-dimer (<0.5 to 1.4 ug/ml [P < 0.01]) and CRP (0.26 to 1.5 mg/dl [P < 0.001]). An IL-6R antagonist suppressed the increase in CRP, but not D-dimer. CONCLUSION: The pig artery patch model has proved valuable for determining immunosuppressive regimens that prevent sensitization to pig antigens. This model also provides information on the sustained systemic inflammation in xenograft recipients (SIXR). An IL-6R antagonist may help suppress this response.

Ganciclovir-resistant cytomegalovirus infections among lung transplant recipients are associated with poor outcomes despite treatment with foscarnet-containing regimens.

Ganciclovir-resistant cytomegalovirus (CMV) infections are reported infrequently among lung transplant recipients receiving extended valganciclovir prophylaxis. We performed a single-center, retrospective review of ganciclovir-resistant CMV infections in a program that employed valganciclovir prophylaxis for ≥6 months after lung transplant. CMV infections were diagnosed in 28% (170/607) of patients. UL97 mutations were detected in 9.4% (16/170) of CMV-infected patients at a median of 8.5 months posttransplant (range, 5 to 21) and despite prophylaxis for a median of 7 months (range, 4 to 21). UL97 mutations were canonical; 25% (4/16) of strains carried concurrent UL54 mutations. Ganciclovir-resistant CMV was more likely with breakthrough infections (75% [12/16] versus 19% [30/154]; P = 0.00001) and donor positive/recipient negative (D+/R-) serostatus (75% versus 45% [69/154]; P = 0.03). The median whole-blood CMV load was 4.13 log10 copies/cm(3) (range, 2.54 to 5.53), and 93% (14/15) of patients had low-moderate immune responses (Cylex Immunoknow). Antiviral therapy was successful, failed, or eradicated viremia followed by relapse in 12% (2/16), 31% (5/16), and 56% (9/16) of patients, respectively. Eighty-seven percent (14/16) of patients were treated with foscarnet-containing regimens; toxicity developed in 78% (11/14) of these. Median viral load half-life and time to viremia eradication among foscarnet-treated patients were 2.6 and 23 days, respectively, and did not correlate with protection from relapse. Sixty-nine percent (11/16) of patients developed CMV pneumonitis, and 25% (4/16) died of it. Serum viral load was independently associated with death among foscarnet-treated patients (P = 0.04). In conclusion, ganciclovir-resistant CMV infections remained a major cause of morbidity and mortality following lung transplantation. Foscarnet-based regimens often eradicated viremia rapidly but were ineffective in the long term and limited by toxicity.

Temporal leukocyte numbers and granulocyte activation in pulsatile and rotary ventricular assist device patients.

Individual ventricular assist device (VAD) design may affect leukocytes and impact immunity. Few studies have presented leukocyte and infection profiles in VAD patients over the course of the implant period. CD11b (MAC-1) expression on granulocytes is an indicator of activation during inflammation, mediating extravasation and the release of reactive oxygen species in tissue. No reported studies have presented MAC-1 expression on circulating granulocytes in VAD patients. Fifty-six patients implanted at a single center with a HeartMate II (HMII; n = 32), HeartWare (HW; n = 12), or Thoratec pneumatic VAD (PVAD; n = 12) between 1999 and 2011 were followed for 120 days of support. The leukocyte profiles and infectious events of all patients were evaluated; additionally, a subset had MAC-1 expression on circulating granulocytes was measured (HMII n = 9; HW n = 7; PVAD n = 4). All groups exhibited a significant peak in leukocyte numbers at postoperative day (POD) 14 while simultaneously experiencing a significant decrease in hematocrit. HMII patients exhibited a 3.2-fold increase in granulocyte MAC-1 expression at POD 14, and the temporal trend over the implant period differed from that experienced by HW patients. Further, HW patients experienced significantly fewer infection events. Alterations in leukocyte profiles and granulocyte activation experienced by VAD patients appear to be device-specific. Elevations in leukocyte activation may be related to an increased risk for infection, although the specific relationship between these phenomena in this patient group is not known.

Prospective, observational study of voriconazole therapeutic drug monitoring among lung transplant recipients receiving prophylaxis: factors impacting levels of and associations between serum troughs, efficacy, and toxicity.

Voriconazole prophylaxis is common following lung transplantation, but the value of therapeutic drug monitoring is unknown. A prospective, observational study of lung transplant recipients (n = 93) receiving voriconazole prophylaxis was performed. Serum voriconazole troughs (n = 331) were measured by high-pressure liquid chromatography. The median initial and subsequent troughs were 1.91 and 1.46 µg/ml, respectively. The age of the patient directly correlated with initial troughs (P = 0.005). Patients that were ≥ 60 years old and cystic fibrosis patients were significantly more likely to have higher and lower initial troughs, respectively. In 95% (88/93) of patients, ≥ 2 troughs were measured. In 28% (25/88) and 32% (28/88) of these patients, all troughs were ≤ 1.5 µg/ml or >1.5 µg/ml, respectively. Ten percent (10/93) and 27% (25/93) of the patients developed invasive fungal infection (tracheobronchitis) and fungal colonization, respectively. The median troughs at the times of positive and negative fungal cultures were 0.92 and 1.72 µg/ml (P = 0.07). Invasive fungal infections or colonization were more likely with troughs of ≤ 1.5 µg/ml (P = 0.01) and among patients with no trough of >1.5 µg/ml (P = 0.007). Other cutoff troughs correlated less strongly with microbiologic outcomes. Troughs correlated directly with aspartate transferase levels (P = 0.003), but not with other liver enzymes. Voriconazole was discontinued due to suspected toxicity in 27% (25/93) of the patients. The troughs did not differ at the times of suspected drug-induced hepatotoxicity, central nervous system (CNS) toxicity, or nausea/vomiting and in the absence of toxicity. Voriconazole prophylaxis was most effective at troughs of >1.5 µg/ml. A cutoff for toxicity was not identified, but troughs of >4 µg/ml were rare. The data support a target range of >1.5 to 4 µg/ml.

Invasive aspergillosis among heart transplant recipients is rare but causes rapid death due to septic shock and multiple organ dysfunction syndrome.

Between 2000 and 2011, proven or probable invasive aspergillosis (IA) was diagnosed in 1.7% (8/455) of heart transplant (HTx) recipients at our center, in the absence of antifungal prophylaxis. All patients had invasive pulmonary infections and 75% (6/8) were diagnosed during 2 separate 3-month periods. Cases were notable for their association with septic shock and multiple organ dysfunction syndrome (MODS) (75%, 6/8 each), non-specific clinical and radiographic findings, and rapid mortality despite mould-active antifungal therapy (88%, 7/8; occuring at a median 11 days after diagnosis). All patients had predisposing conditions known to be risk factors for IA. For patients with early IA (within 90 days of HTx), conditions included hemodialysis, thoracic re-operation, and the presence of another case in the institution within the preceding 3 months. For late-onset IA, conditions included hemodialysis and receipt of augmented immunosuppression. Clinicians should suspect IA in HTx recipients with risk factors who present with non-specific and unexplained respiratory syndromes, including those in septic shock and MODS, and institute prompt antifungal therapy without waiting for the results of cultures or other diagnostic tests.

Posaconazole serum concentrations among cardiothoracic transplant recipients: factors impacting trough levels and correlation with clinical response to therapy.

Fifty-six serum posaconazole trough levels were measured in 17 cardiothoracic transplant recipients. Initial levels were ≤ 0.5, 0.51 to 0.99, and ≥ 1 µg/ml for 47, 29, and 24% of patients, respectively. Median trough levels associated with therapeutic success were higher than those associated with failure (1.55 versus 0.34 µg/ml; P = 0.006). Patients with levels consistently >0.5 µg/ml were more likely to have successful outcome (P = 0.055). Age ≥ 65 years, oral administration, and absence of proton pump inhibitors were associated with higher levels of posaconazole (P = 0.006, 0.006, and 0.001, respectively).

Ex Vivo Expanded Donor Alloreactive Regulatory T Cells Lose Immunoregulatory, Proliferation, and Antiapoptotic Markers After Infusion Into ATG-lymphodepleted, Nonhuman Primate Heart Allograft Recipients.

BACKGROUND: Regulatory T cell (Treg) therapy is a promising approach to amelioration of allograft rejection and promotion of organ transplant tolerance. However, the fate of infused Treg, and how this relates to their therapeutic efficacy using different immunosuppressive regimens is poorly understood. Our aim was to analyze the tissue distribution, persistence, replicative activity and phenotypic stability of autologous, donor antigen alloreactive Treg (darTreg) in anti-thymocyte globulin (ATG)-lymphodepleted, heart-allografted cynomolgus monkeys. METHODS: darTreg were expanded ex vivo from flow-sorted, circulating Treg using activated donor B cells and infused posttransplant into recipients of major histocompatibility complex-mismatched heart allografts. Fluorochrome-labeled darTreg were identified and characterized in peripheral blood, lymphoid, and nonlymphoid tissues and the graft by flow cytometric analysis. RESULTS: darTreg selectively suppressed autologous T cell responses to donor antigens in vitro. However, following their adoptive transfer after transplantation, graft survival was not prolonged. Early (within 2 wk posttransplant; under ATG, tacrolimus, and anti-IL-6R) or delayed (6-8 wk posttransplant; under rapamycin) darTreg infusion resulted in a rapid decline in transferred darTreg in peripheral blood. Following their early or delayed infusion, labeled cells were evident in lymphoid and nonlymphoid organs and the graft at low percentages (<4% CD4+ T cells). Notably, infused darTreg showed reduced expression of immunoregulatory molecules (Foxp3 and CTLA4), Helios, the proliferative marker Ki67 and antiapoptotic Bcl2, compared with preinfusion darTreg and endogenous CD4+CD25hi Treg. CONCLUSIONS: Lack of therapeutic efficacy of infused darTreg in lymphodepleted heart graft recipients appears to reflect loss of a regulatory signature and proliferative and survival capacity shortly after infusion.

Preoperative Vitamin K Reduces Blood Transfusions at Time of Left Ventricular Assist Device Implant.

BACKGROUND: Congestive heart failure patients have hepatic congestion and abnormal coagulation profiles, increasing perioperative bleeding at time of ventricular assist device implantation. This study examined the impact of the preoperative administration of vitamin K on perioperative blood transfusion requirements. METHODS: Retrospectively, 190 patients met inclusion criteria. Patients received no vitamin K (n = 62) or two 10-mg doses of intravenous vitamin K (n = 128) in the 24 hours before assist device implantation. Primary end points included transfusion requirements and reexploration rates for bleeding. Secondary outcomes were pump thrombosis and in-hospital mortality. RESULTS: Baseline characteristics were similar between the 2 groups, with slight differences (not statistically significant) noted in the Interagency Registry for Mechanically Assisted Circulatory Support profile and total bilirubin levels. The only significant difference noted was the year of implantation (P < .001). Blood product usage was significantly lower in the vitamin K group compared to the no vitamin K group (P < .001). Higher rates of reexploration for bleeding (29.7% vs 13.6%, P = .023) and death at hospital discharge (16.2% vs 2.8%, P = .004) were noted for the no vitamin K group compared with the vitamin K group. After adjusting for age, sex, race, body mass index, Interagency Registry for Mechanically Assisted Circulatory Support profile, total bilirubin, surgeon, and year of operation, reexploration rates and death did not achieve statistical significance. No statistically significant difference was observed in stroke and pump thrombosis rates between the 2 groups. CONCLUSIONS: Preoperative vitamin K administration may help reduce blood product use without any increased risk for strokes or pump thrombosis.

Distal landing zone optimization before endovascular repair of aortic dissection.

BACKGROUND: The general goals of endovascular management in chronic distal thoracic aortic dissection are optimizing the true lumen, maintaining branch patency, and promoting false lumen (FL) thrombosis. Distal seal can be challenging in chronic distal thoracic aortic dissection due to the well-established secondary fenestrations and fibrotic septum. We describe our approach of distal landing zone optimization (DLZO) to enable full-diameter contact of the distal endoprosthesis. MATERIALS AND METHODS: Our experience includes 19 procedures in 16 patients (12 male, age 68 ± 8 years) between May 2014 and November 2017. A history of previous ascending repair for type A dissection was present in 8 patients. Treatment indication was enlarging aneurysm in all subjects, and 4 patients had associated chronic visceral or distal ischemia. Point septal fenestrations were expanded by serial balloon dilation and/or wire-pull approaches. Balloon molding was used to ensure complete endograft apposition and FL collapse. RESULTS: One death occurred due to aortic perforation during wire-pull fenestration in a patient with heavily calcified and angulated aorta. The remaining procedures were accomplished safely and successfully. Balloon fenestration was used in 16 procedures, alone or in combination with a limited wire pull component. Adjunct procedures for distal seal included surgeon-modified fenestrated stent graft (3), iliac branch device (3), parallel superior mesenteric artery stent-graft (1), renal artery or superior mesenteric artery stent-graft (4), iliac stent (3), and plug obliteration of FL (5). Reintervention was required in 3 patients due to delayed loss of seal after the initial procedure (3, 8, and 12 months). Two were managed by repeat DLZO and distal extension. The third had distal extension via a surgeon-modified fenestrated stent-graft component. Follow-up imaging was available in 14 patients (16.0 ± 12.5 months, range: 1-33), with stable or regressed sac diameter with complete or near-complete thrombosis of the FL in all patients. CONCLUSIONS: DLZO enabled creation of a distal seal zone in all patients. Residual retrograde filling of the FL is a marker of procedure failure, especially when seal segment length or feasible endoprosthesis oversizing are marginal. Insufficient landing segment can be circumvented with the use of a fenestrated or branched device to accomplish seal in the visceral aorta or iliac bifurcation. Adjunct FL ablation is also a valuable technique to promote FL thrombosis.

Right Heart Failure in Different Left Ventricular Assist Devices: Single-Center Experience.

Background: Right heart failure (RHF) following left ventricular assist device (LVAD) implantation increases morbidity and mortality for those who develop this complication. The purpose of this study was to assess the differences in incidence of RHF and outcomes between 2 types of continuous-flow LVADs at a single center. Methods: From January 2012 through June 2016, 184 patients were implanted with a continuous-flow LVAD (161 patients with the HeartMate II and 23 patients with the HeartWare device) either as a bridge to transplant or as destination therapy. Preoperative demographics, medical history, laboratory values, hemodynamics, and device type were analyzed to determine the variables associated with RHF and mortality. Results: Preoperative variables between the 2 groups were homogeneous. Most patients were Interagency Registry for Mechanically Assisted Circulatory Support profile 1 or 2 (92%) and New York Heart Association class IV (81%). More patients in the HeartMate II group had the indication of destination therapy (54% vs 30%), while more patients in the HeartWare group were implanted as bridge to transplant (70% vs 46%). RHF occurred in 57% of HeartWare patients compared to 16% of patients who received the HeartMate II (P=0.0001). After propensity score analysis, patients receiving the HeartWare device had increased odds for RHF (P=0.0013) and renal failure requiring dialysis (P=0.0135). The HeartMate II patient survival rate exceeded the HeartWare patient survival rate at 1 year (82.1% vs 67.2%) and at 2 years (74.6% vs 61.7%), but this difference did not achieve statistical significance (log-rank P=0.087). Conclusion: These results indicate that device type may affect RHF incidence and mortality. Studies at other centers are needed to replicate these findings.

Left Ventricular Assist Device Inflow Cannula Position May Contribute to the Development of HeartMate II Left Ventricular Assist Device Pump Thrombosis.

BACKGROUND: Pump thrombosis (PT) is a dreaded complication after left ventricular assist device (LVAD) implantation. Problems with inflow cannula (IC) position may precipitate thrombus development. We sought to determine if IC position contributes to the development of PT. METHODS: We conducted a retrospective review of 76 HeartMate II LVAD implants. The angle of the IC (AIC) to the horizontal plane was measured on chest x-rays. Patients who developed PT (PT group) were compared to the remaining patients (control group). RESULTS: The mean age at implantation was 56 ± 14 years, and 82% of the patients were male. Ten patients (13%) developed PT. Six (60%) required device exchange, and 4 (40%) were managed with anticoagulation and/or thrombolysis. The median AIC for all patients at implantation was 59° (range, 38°-98°; 25th-75th interquartile range, 50°-75°). In the PT group, the median AIC was larger at the time of PT diagnosis compared to implantation (70° vs 60°, P = 0.005). In the control group, the median AIC was also larger at follow-up compared to implantation (61° vs 58°, P < 0.001) although to a lesser degree than in the PT group. No difference was seen in the median AIC between the PT group and the control group at implantation (60° vs 58°, respectively; P = 0.668) or at follow-up (70° vs 61°, respectively; P = 0.309). However, the median AIC at follow-up in the PT group was significantly larger than the median AIC at implantation in the control group (70° vs 58°, respectively; P = 0.014). CONCLUSION: The HeartMate II LVAD IC position contributes to the development of PT. Regular monitoring of cannula position may help identify patients at risk for this problem.

Clinical experience with temporary right ventricular mechanical circulatory support.

OBJECTIVES: This study sought to determine if indication for support affects the outcomes after temporary right ventricular mechanical circulatory support after postcardiotomy cardiogenic shock, cardiac transplant, or left ventricular assist device placement. METHODS: A retrospective review was performed on 80 patients receiving a right ventricular assist device. Data were collected from a prospectively maintained database. Kaplan-Meier survival analysis was performed to compare survival between groups. Multivariate regression analysis was performed to identify risk factors for failure to wean from support. RESULTS: The indication for support was postcardiotomy cardiogenic shock in 13 patients (16%), cardiac transplant in 25 patients (31%), and left ventricular assist device in 42 patients (53%). Median support time was 6 days. Device was successfully weaned in 6 postcardiotomy cardiogenic shock cases (46%), 21 cardiac transplant cases (84%), and 35 left ventricular assist device cases (83%). Survival was worse for patients with postcardiotomy cardiogenic shock compared with patients with a left ventricular assist device. Survival up to 3 months was better for patients who received immediate (n = 43) versus delayed (n = 37) support (79% vs 46%, P = .003). Weaning and survival remained static across implant era. Risk factor analysis identified postcardiotomy cardiogenic shock indication (odds ratio, 0.161; P = .007; confidence interval, 0.043-0.600) as an independent negative predictor of weaning from mechanical support. CONCLUSIONS: Temporary right ventricular mechanical support remains an effective treatment strategy after left ventricular assist device placement with immediate support resulting in superior short-term survival. Caution should be applied in postcardiotomy cardiogenic shock when weaning and survival are poor. Overall survival outcomes have remained relatively static over time.

Coronary revascularization in patients with obstructive sleep apnea syndrome.

BACKGROUND: There is a paucity of clinical information regarding therapy for ischemic heart disease (IHD) in patients with obstructive sleep apnea syndrome (OSAS). We evaluated our experience with surgical revascularization in this subset of patients. METHODS: Between January 1998 and April 2001, 20 patients with OSAS underwent isolated coronary artery bypass grafting (CABG). Outcomes were compared to a matched control group consisting of 65 patients. RESULTS: Patients with OSAS and the controls were similar with regard to age (65.8 years versus 65.2 years), ejection fraction (44.5% versus 46.9%), and systolic blood pressure (141 mmHg versus 142 mmHg). However, they were comparatively heavier (212 lb versus 188 lbs, P < .03), had higher pulmonary artery pressures (42 mmHg versus 34 mmHg, P < .001), higher pulmonary capillary wedge pressures (17 mmHg versus 14 mmHg, P < .01), higher left ventricular end diastolic pressures (20 mmHg versus 18 mmHg, P < .04), and a greater incidence of diabetes (55% versus 30%, P = .049). Patients with OSAS were more likely to require prolonged ventilation (40% versus 0%, P < .001) and tracheostomy (10% versus 0%, P = .01) and have a protracted intensive care unit (ICU) course (9 days versus 3 days, P = .002) and hospitalization (24 versus 13, P = .003). There were no peri-operative deaths, and both groups had significant improvement in angina and functional class. At a mean follow-up of 59 months, angina recurrence was 10% and survival was 95% in patients with OSAS. CONCLUSION: Patients with OSAS and IHD requiring coronary revascularization have substantial risk for pulmonary morbidity that impacts the duration of hospitalization but not mortality. Good symptom control and early to mid-term survival may be achieved in this subset of patients with aggressive peri-operative management of their OSAS.

Heart Xenotransplantation: Historical Background, Experimental Progress, and Clinical Prospects.

If pig hearts could be transplanted successfully into patients with end-stage cardiac failure, the critical shortage of hearts from deceased human donors would be overcome. The several attempts at cardiac xenotransplantation carried out in the 20th century, usually with hearts from nonhuman primates (NHPs), are reviewed, as are the surgical techniques used in experimental heart transplantation in animals. For a number of reasons, the pig has been selected as the potential source of organs for clinical transplantation. The major pathobiological barriers that the pig presents, and progress in overcoming these barriers either by genetic engineering of the pig or by the administration of novel immunosuppressive agents, are described. Currently, non-life-supporting pig heterotopic heart transplantation in NHPs has extended to more than 2 years in 1 case, with life-supporting orthotopic heart transplantation of almost 2 months. Future approaches to resolve the remaining problems and the selection of patients for the initial clinical trials are briefly discussed.