Similar transplantation outcomes in patients bridged with cardiac assist devices for acute cardiogenic shock versus chronic heart failure.

BACKGROUND: Heart failure (HF) patients may require cardiac assist device implantation prior to transplantation (Tx) because of either acute cardiogenic shock (ACS), with no prior history of HF, or for progression of pump failure in the setting of chronic HF. AIMS: To investigate whether patients implanted with a cardiac assist device for ACS, have similar post-Tx outcomes as those who underwent cardiac assist device implantation because of progressive chronic HF. METHODS AND RESULTS: We compared post-Tx outcomes of consecutive patients bridged due to ACS (Acute Group) with the outcomes of patients bridged due to deterioration of chronic HF (Chronic Group). Seventy-three patients had a cardiac assist device implanted and underwent subsequent cardiac Tx. Thirty-five patients (48%) had a cardiac assist device implanted due to ACS, most often caused by massive acute myocardial infarction, and 38 patients (52%) because of progressive chronic HF. Despite greater compromise at the time of implantation, the Acute Group recovered satisfactorily and underwent Tx with similar post-Tx survival rates as the Chronic Group patients [1-year survival: 88.6% vs 86.8%, p=0.80, actuarial survival (mean follow-up 4.2 years): 80.0% vs 81.6%, p=0.86)]. Furthermore, no significant differences were observed between the 2 groups in various post-Tx events. CONCLUSION: Patients with ACS who underwent emergency cardiac assist device implantation as bridge to Tx had similar post-Tx outcomes as their more chronically ill counterparts who underwent device implantation on a non-urgent basis.

Early experience with sirolimus in lung transplant recipients with chronic allograft rejection.

BACKGROUND: Chronic lung allograft rejection, commonly manifest as obliterative bronchiolitis (OB/BOS), hinders long-term survival after lung transplantation (LT). OB/BOS is traditionally treated with augmented immunosuppression and results in short-term stabilization in pulmonary function for most patients. However, peribronchiolar fibroproliferation and airway obstruction usually recur despite initial improvements seen with increases in immunosuppression. In this observational, uncontrolled study, the effect of sirolimus, a novel immunosuppressant with anti-proliferative activity, was assessed in LT patients with OB/BOS. METHODS: Between June 1999 to November 2000, LT recipients with newly diagnosed or progressive OB/BOS received sirolimus in combination with a calcineurin inhibitor (CI) and prednisone. Pulmonary function, laboratory data and adverse effects were monitored for the first 24 weeks of therapy. RESULTS: Sirolimus was utilized in 12 LT recipients with OB/BOS. After drug initiation, 58% of patients required a reduction in CI dose to maintain appropriate CI trough concentrations. Despite CI dose reduction, serum creatinine rose in 75% of patients. Unexpected adverse effects included anemia of chronic disease (100%), edema (50%) and malignancy (17%). For the group, the rate of change in FEV(1) and FEF(25%-75%) was unchanged with sirolimus, but individual responses varied. CONCLUSIONS: For the group, the decline in pulmonary function was not affected by the addition of sirolimus. However, among individuals with rapidly declining pulmonary mechanics, sirolimus resulted in stabilization or improvement in pulmonary function. Significant adverse effects resulted from combination sirolimus plus CI therapy. Until optimal dosing strategies and a more complete adverse effect profile are established, combination therapy should be utilized cautiously in these patients.

Effect of reversible pulmonary hypertension on outcomes after heart transplantation.

BACKGROUND: Conflicting data exist regarding the impact of reversible pulmonary hypertension (PHTN) on post-transplant (Tx) outcomes. In this study we sought to determine the influence of reversible PHTN on outcomes after Tx. METHODS: We retrospectively reviewed the records of adult patients who underwent heart Tx from 1993 to 2002. Patients were grouped depending on their measured pulmonary vascular resistance (PVR). Group 1 patients had a pre-Tx pulmonary vascular resistance (PVR) of < 3 Wood units (WU). Patients with reversible PHTN, defined as pre-Tx PVR > or = 3 WU and reversing to < 3 WU either with sub-lingual or intravenous vasodilatory agents, were divided into two groups based on their PVR before the reversibility test (PVR: Group 2, 3 to 4.5 WU; Group 3, > 4.5 WU). RESULTS: Records for 222 adult heart recipients were reviewed (Group 1, n = 171; Group 2, n = 35; Group 3, n = 16). Baseline clinical characteristics (age, gender, heart failure etiology, history of diabetes, ischemic time, donor age and gender) were similar in the three groups and the average follow-up was 58 months. One-month and 1-year mortality (Groups 1, 2 and 3: 2%, 0% and 13%; and 8%, 0% and 13%, respectively) did not differ significantly between groups. Actuarial mortality was assessed using Cox regression analysis, adjusted for age and gender, and no increased risk of death was demonstrated for patients with reversible PHTN (for Group 2: multivariate hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.17 to 1.32, p = 0.15; for Group 3: HR 0.98, CI 0.34 to 2.84, p = 0.97). No differences were observed between the three groups for various post-Tx events, such as hospital stay, ICU stay, extubation time, transfusions, acute allograft dysfunction, acute hepatic dysfunction, acute and chronic renal dysfunction, infections, neurologic complications, gastrointestinal complications and coronary allograft vasculopathy. CONCLUSIONS: Reversible pulmonary hypertension is associated with similarly good post-transplant survival outcomes and morbidity, regardless of severity.

Multivariate predictors of heart transplantation outcomes in the era of chronic mechanical circulatory support.

BACKGROUND: Determining which pretransplantation (TX) characteristics predict the development of chronic renal dysfunction (CRD) or death after heart TX would enable more accurate risk assessment at the time of candidate evaluation. METHODS: A cohort of 278 patients underwent TX in three hospitals between 1993 and 2002. Predictive models for CRD (serum creatinine consistently above 2 mg/dL) and allograft loss (death or re-TX) were constructed using logistic and Cox regression, respectively. RESULTS: Using logistic regression, CRD was more likely to develop in TX patients if they had a larger body surface area (odds ratio [OR] = 5.8 per m2, 95% confidence interval [CI] = 1.04 to 31.9, p = 0.04) or were inotrope dependent (OR = 1.8, 95% CI = 0.90 to 3.7, p = 0.09). Notably, the implementation of mechanical circulatory support as bridge to transplantation decreased the risk of CRD (OR = 0.30, 95% CI = 0.12 to 0.72, p = 0.007). Cox analysis demonstrated independent predictive ability of improved survival for males (hazard ratio [HR] = 0.42, 95% CI = 0.21 to 0.83, p = 0.01). Worse survival was observed with prior sternotomy (HR = 3.5, 95% CI = 2.0 to 6.0, p < 0.001), diabetes mellitus (HR = 1.9, 95% CI = 0.98 to 3.9, p = 0.06), and elevated serum creatinine (HR = 2.8 per mg/dL, 95% CI = 1.3 to 5.8, p = 0.007). CONCLUSIONS: Certain pretransplant characteristics clearly predispose a patient to the development of CRD or increased mortality after heart transplantation. Interestingly, the risk of CRD after heart transplantation is greater for patients bridged to transplant with inotropes than with mechanical circulatory support. When hemodynamically indicated, timely implementation of pretransplant mechanical circulatory support should be considered.

Prevalence and risks of allosensitization in HeartMate left ventricular assist device recipients: the impact of leukofiltered cellular blood product transfusions.

OBJECTIVE: Allosensitization of left ventricular assist device recipients has been associated with perioperative transfusion of cellular blood products. The relative sensitizing contribution of leukofiltered cellular blood products, however, remains unclear. We investigated the pattern of sensitization in left ventricular assist device recipients in relation to cellular blood product transfusions received. METHODS: Seventy-one consecutive nonsensitized recipients of the HeartMate left ventricular assist device (Thoratec Corporation, Pleasanton, Calif) as a bridge to transplantation were reviewed. Panel-reactive HLA antibody levels at consecutive times after device implantation were correlated with perioperative cellular blood product transfusions. RESULTS: Fifty-four patients received leukofiltered cellular blood products (transfused), whereas 17 patients received only fresh-frozen plasma (nontransfused). Among nontransfused patients, 58.8% (10/17) became sensitized during mechanical support, versus 35.2% of transfused patients (19/54, P = .15). There was a trend toward more sensitization during the 12 weeks after device placement in nontransfused patients. Kaplan-Meier analysis revealed significantly more sensitization in nontransfused patients than in transfused patients, despite equal rates of transplantation (P = .05). A dose-response analysis revealed significant trends toward less sensitization and lower peak panel-reactive antibody level with more cellular blood product transfusions (P = .04). Multivariate Cox regression revealed only increasing transfusions to be associated with a reduced risk of sensitization (hazard ratio 0.18, P = .01). CONCLUSIONS: Sensitization becomes more prevalent with increasing length of support. Avoidance of perioperative leukocyte-filtered cellular blood product transfusions does not decrease the incidence or degree of HLA sensitization. Conversely, cellular blood product transfusions may be associated with lessened alloimmunization and may mitigate the sensitization seen in recipients of the HeartMate left ventricular assist device as a bridge to transplantation.

Low-dose prophylactic intravenous immunoglobulin does not prevent HLA sensitization in left ventricular assist device recipients.

BACKGROUND: The use of left ventricular assist devices is associated with human leukocyte antigen (HLA) allosensitization. We investigated whether prophylactic treatment with low-dose intravenous immunoglobulin (IVIG), analogous to the use of IgG anti-D (anti-Rh) in preventing Rh immunization, can abrogate HLA allosensitization after left ventricular assist device implantation. METHODS: We retrospectively reviewed the data from 84 consecutive heart failure patients who underwent implantation of a left ventricular assist device as a bridge to transplantation. After implantation, panel reactive antibody (PRA) was measured biweekly to assess sensitization (defined by PRA > 10%). Patients who were sensitized before left ventricular assist device implantation were excluded from further analysis (n = 12). Patients who either did not require perioperatively transfusions of cellular blood products or received other immunomodifying regimens were also excluded from further analysis (n = 21). The rest of the patients were divided into two groups based on whether they received IVIG, 10 g daily for 3 days (IVIG group, n = 26; non-IVIG group, n = 25). The decision as to whether patients received IVIG was not randomized but was based on surgeon preference. RESULTS: The sensitization rates (expressed as ratio of sensitized patients to total patients at risk) in the two groups were similar at consecutive time points (2, 4, 6, 8, 12, 20 weeks) after left ventricular assist device implantation. Also, mean PRA at the same time points did not differ between the two groups. Overall, 34.6% (9 of 26) of the IVIG group became sensitized during mechanical support, compared with 32% (8 of 25) of the non-IVIG group (p = 1.0). A PRA of 90% or greater (high-degree sensitization) occurred in 15.3% (4 of 26) of the IVIG group and 12.0% (3 of 25) of the non-IVIG group (p = 0.5). CONCLUSIONS: The use of low-dose prophylactic IVIG after left ventricular assist device implantation affects neither the incidence nor the severity of HLA allosensitization.

Effect of mechanical circulatory support on outcomes after heart transplantation.

BACKGROUND: Mechanical circulatory support (MCS) before heart transplantation was previously associated with worse post-transplant outcomes than when MCS was not required. Given the changes in technology, expertise, patient selection, and timing of subsequent transplantation, we hypothesized that patients who require MCS before heart transplantation have similar outcomes after transplantation as those not requiring pre-transplant MCS. METHODS: We retrospectively reviewed 278 patients who underwent cardiac transplantation from 1993 to 2002. MCS was required in 72 patients (HeartMate LVAS in 66, CardioWest Total Artificial Heart in 6) and was not required in 206 patients. The influence of pre-transplant MCS on post-transplant outcomes was assessed in the 2 groups. RESULTS: Baseline clinical characteristics (age, gender, etiology of heart failure, history of diabetes mellitus, and donor age and gender) were similar in the 2 groups. One-month and 1-year survival after transplantation did not differ between the groups (MCS, 92% and 85%, respectively vs no MCS, 97% and 92%, respectively). Similar proportions of patients were free from rejection (International Society for Heart and Lung Transplantation score >or=3A) at 1 year of follow-up (MCS, 56% vs no MCS, 52%, p = 0.60). No difference was observed between MCS and no MCS patients in other post-transplant events such as hospital stay, intensive care unit stay, extubation time, acute allograft dysfunction, reoperation rates, acute renal dysfunction, acute hepatic dysfunction, infections, arrhythmias, thromboembolic complications, neurologic complications, gastrointestinal complications and the development of cardiac allograft vasculopathy. The incidence of chronic renal insufficiency was actually lower in the MCS Group (15.3% vs 37.9%, p = .001). CONCLUSION: Post-transplant outcomes after pre-transplant use of MCS are similar to those when MCS is not required.

Transforming growth factor-beta1 induces Nox4 NAD(P)H oxidase and reactive oxygen species-dependent proliferation in human pulmonary artery smooth muscle cells.

Transforming growth factor-beta1 (TGF-beta1) is abundantly expressed in pulmonary hypertension, but its effect on the pulmonary circulation remains unsettled. We studied the consequences of TGF-beta1 stimulation on freshly isolated human pulmonary artery smooth muscle cells (HPASMC). TGF-beta1 initially promoted differentiation, with upregulated expression of smooth muscle contractile proteins. TGF-beta1 also induced expression of Nox4, the only NAD(P)H oxidase membrane homolog found in HPASMC, through a signaling pathway involving Smad 2/3 but not mitogen-activated protein (MAP) kinases. TGF-beta1 likewise increased production of reactive oxygen species (ROS), an effect significantly reduced by the NAD(P)H oxidase flavoprotein inhibitor diphenylene iodonium (DPI) and by Nox4 siRNAs. In the absence of TGF-beta1, Nox4 was present in freshly cultured cells but progressively lost with each passage in culture, paralleling a decrease in ROS production by HPASMC over time. At a later time point (72 h), TGF-beta1 promoted HPASMC proliferation in a manner partially inhibited by Nox4 small interfering RNA and dominant negative Smad 2/3, indicating that TGF-beta1 stimulates HPASMC growth in part by a redox-dependent mechanism mediated through induction of Nox4. HPASMC activation of the MAP kinases ERK1/2 was reduced by the NAD(P)H oxidase inhibitors DPI and 4-(2-aminoethyl)benzenesulfonyl fluoride, suggesting that TGF-beta1 may facilitate proliferation by upregulating Nox4 and ROS production, with transient oxidative inactivation of phosphatases and augmentation of growth signaling cascades. These findings suggest that Nox4 is the relevant Nox homolog in HPASMC. This is the first observation that TGF-beta1 regulates Nox4, with important implications for mechanisms of pulmonary vascular remodeling.

Membrane oxygenation is superior to parabiotic support in blood-reperfused isolated hearts.

BACKGROUND: Isolated heart preparations are often used for myocardial research, but can become complex and difficult when blood is used as the perfusate. We compared the utility and effectiveness of a parabiotic isolated heart system perfused from a support animal to an equivalent system supported by a pediatric membrane oxygenator. MATERIALS AND METHODS: Whole blood reperfused rabbit hearts were supported on a standard Langendorff column by either a parabiotic support animal (n = 10), or an in-line pediatric membrane oxygenator (n = 12). Support animals were mechanically ventilated, and hemodynamically monitored. Perfusate acid-base balance, oxygen, carbon dioxide, bicarbonate, and lactate levels were serially monitored during 120 min of perfusion. RESULTS: One-hundred percent of experiments supported with an oxygenator completed the evaluation period without instability, while 40% of parabiotic-supported experiments were terminated early because of donor animal hemodynamic instability (P < 0.0001). Parabiotic experiments developed a refractory acidosis (pH at 120 min: parabiotic 7.31 +/- 0.14 versus oxygenator 7.42 +/- 0.4, P = 0.01) related to a progressive rise in lactate (at 120 min: parabiotic 4.0 +/- 2.6 mmol/L versus oxygenator 0.71 +/- 1.3 mmol/L, P < 0.01). Parabiotic experiments demonstrated inferior oxygenation than oxygenator experiments (pO(2) 313 +/- 72 mmHg versus 500 +/- 42 mmHg, P < 0.0001). In this and other experiments, membrane oxygenators have been reused up to 25 times. CONCLUSIONS: Small animal isolated heart experiments perfused with blood are more successful, more efficient, and more cost effective when supported with a membrane oxygenator rather than a support animal. Membrane oxygenators reduce complexity, variability, and animal wastage in isolated heart experiments.

Utility of histologic parameters in screening for antibody-mediated rejection of the cardiac allograft: a study of 3,170 biopsies.

BACKGROUND: Diagnostic criteria for antibody-mediated rejection (AMR) of the cardiac allograft have recently been proposed as part of the International Society for Heart and Lung Transplantation (ISHLT) biopsy grading scheme. Histologic features of vascular adherence of macrophages (VASC) and endothelial activation or swelling in capillaries (ENDO) are proposed as criteria to prompt the immunohistochemical investigation of biopsies for AMR. The aim of this study was to determine whether VASC and ENDO are adequate to act as screening parameters to trigger further AMR investigation. METHODS: We examined our database of biopsy findings where histologic vascular parameters as well as immunofluorescence (IF) to detect AMR were collected (n = 3,170). Histologic parameters were graded semi-quantitatively on a scale from 1 to 5, where 1 = absence and 5 = obvious and generalized presence of the finding. RESULTS: Seven hundred sixty-eight of 3,170 biopsies had IF findings diagnostic of AMR in the absence of cellular rejection (ISHLT = 0). ENDO had a sensitivity of 63% and a specificity of 80%. VASC had a sensitivity of 30% and specificity of 99%. Combining the interpretation of the 2 tests did not result in a significant improvement of test sensitivity. CONCLUSIONS: Neither ENDO, VASC nor the combination of the tests indicated sufficiently high sensitivity to serve as a screening tool before further diagnostic investigation for AMR. Immunohistochemical testing remains necessary in the majority of cases to identify AMR.

PDGF(BB) increases myocardial production of VEGF: shift in VEGF mRNA splice variants after direct injection of bFGF, PDGF(BB), and PDGF(AB).

BACKGROUND: Vascular endothelial growth factor (VEGF) plays an important role in angiogenesis. We hypothesized that a combination of recombinant angiogenic proteins might induce myocardial VEGF production and cause a shift in the mRNA signal produced. MATERIALS AND METHODS: The left ventricles of New Zealand white rabbits were injected with 500 microL of saline, basic fibroblast growth factor (bFGF), platelet-derived growth factor-AB (PDGF(AB)), platelet-derived growth factor-BB (PDGF(BB)), bFGF + PDGF(AB), or bFGF + PDGF(BB). Myocardial VEGF production was analyzed by ELISA while mRNA splice variants were analyzed by RT-PCR 3 and 7 days after injection. RESULTS: PDGF(BB) alone caused the most pronounced induction of VEGF. Three days after injection the induction of VEGF by PDGF(BB) was significant compared to all treatment groups, except the bFGF + PDGF(BB) group. Induction of VEGF by PDGF(BB) was associated with a decrease in mRNA production of VEGF(121) within the myocardium. CONCLUSIONS: Injection of PDGF(BB) induces significant production of VEGF within the myocardium. This induction of VEGF production is associated with a shift toward other, less soluble forms of VEGF. These findings may allow more precise regulation of the myocardial response to therapeutic angiogenesis.