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Biomedical subjects

M Loebe

Publications and source records attributed to M Loebe.

At least 19 recordsLinked to original sources
PubMed2006

[Diabetes and heart transplantation].

Diabetes is frequently encountered in patients presenting with end-stage heart failure to be listed for transplantation. While diabetes used to be a contra-indication for heart transplantation, careful preoperative evaluation and individualized postoperative medication lead to long-term outcome after heart transplantation equal to non-diabetic patients. About 1/3 of transplanted patients develop a post-transplant diabetes. Several risk factors have been identified leading to this condition. Mostly, post-transplant diabetes is of temporary nature. Several studies have shown no impact of diabetes on the incidence of rejection, malignancies, and transplant vasculopathy. However, glucose intolerance must be taken into consideration when planing immunosuppressive therapy since different medications have distinct impact on glucose metabolism after transplant. A multidisciplinary team allows for closely monitoring and treating patients with diabetes after heart transplant.

Diabetes Complications↗
PubMed2004

Effect of acute brain death on release of atrium and B-type natriuretic peptides in an animal model.

INTRODUCTION: Atrium and B-type natriuretic peptides (ANP and BNP) and big endothelin (ET)-1 are markers for severity of heart failure and may be used in the quality assessment of donor hearts. Elevated cardiac troponins predict early graft failure after heart transplantation. This study evaluated the effects of acute brain death (BD) on the release of ANP, BNP, big ET-1, and cardiac troponins in an animal model. MATERIALS AND METHODS: Pigs were randomized into a BD group (n=5) and a control group (n=5). In the first group, acute BD was induced, and anesthesia was stopped. In the control animals, a sham operation was performed, and anesthesia was continued. Parameters were measured at baseline and for 13 hours postoperatively. RESULTS: After acute BD, there were significant hemodynamic changes. In the control group, the BNP level was higher than in the BD group and decreased over time (P =0.016). There was no significant change in BNP release in the BD group up to 13 hours (P =0.1). ANP release remained stable over time in the control group (P =0.35) but decreased in the BD group (P =0.043). The big ET-1 levels were not different between groups. Cardiac troponin I was elevated in the BD group 5 hours after BD (P< 0.05) but remained under 1.5 mg/L throughout the study. CONCLUSION: Acute BD did not lead to an increase of BNP and ANP levels. Moreover, intact brain function seems to augment the release of natriuretic peptides from the myocardium. Further clinical evaluation of prognostic values of natriuretic peptides for the assessment of donor hearts is necessary. Cardiac troponins are a useful additional tool in the evaluation of donor hearts.

Acute Disease↗
PubMed2001

Procalcitonin, a donor-specific predictor of early graft failure-related mortality after heart transplantation.

BACKGROUND: To date, donor-specific markers to predict outcome after heart transplantation (HTx) are unknown. Increased procalcitonin (PCT) levels have been found in infectious inflammation with systemic reactions and/or poor organ perfusion but have not been studied in heart donors. We evaluated PCT as a predictor of early graft failure-related mortality after HTx. METHODS AND RESULTS: PCT and C-reactive protein (CRP) serum concentrations were measured in samples collected immediately before pericardium opening from 81 consecutive brain-dead multiple-organ donors. Donors for high-urgency-status recipients (n=2) were excluded from analysis. The remaining donors were retrospectively divided into 2 groups: donors for recipients who died within 30 days after HTx, after an early graft failure (group II, n=8), and all other donors (group I, n=71). No differences in donor and recipient demographic characteristics were found between groups. Areas under the receiver operating characteristic curves for graft failure-related mortality were 0.71 for PCT and 0.64 for CRP. A PCT value >2 ng/mL as a predictor of graft failure-related mortality had a specificity of 95.8% and sensitivity of 50.0%. The odds ratio for graft failure-related mortality for recipients of hearts from donors with PCT levels >2 ng/mL was 22.7 (unadjusted, 95% CI 3.7 to 137.8, P=0.0007) and 43.8 (after adjustment for prespecified potential confounders, 95% CI 1.4 to 1361.0, P=0.031). CONCLUSIONS: A PCT level >2 ng/mL in a cardiac donor at the time of explantation appears to predict early graft failure-related mortality.

Biomarkers↗
PubMed2001

Value of cardiac troponin I and T for selection of heart donors and as predictors of early graft failure.

BACKGROUND: Cardiac troponin I and T (cTnI and cTnT) are sensitive and specific markers of myocardial damage. We evaluated them for the selection of heart donors and as predictors of early graft failure after heart transplantation. METHODS: cTnI, cTnT, myoglobin, and creatine kinase (CK) levels and its isoenzyme MB (CKMB) activity and mass were measured in serum samples immediately before opening the pericardium from 126 consecutive brain-dead multi-organ donors over 10 years of age inspected by our harvesting team. Donors with serum creatinine >2.0 mg/dL (n=6) were excluded from the analysis. Donors for high-urgency status recipients (n=2) were also excluded. The remaining donors were retrospectively divided into three groups: group I (n=68), grafts with good function; group II (n=11), grafts with impaired function; and group III (n=39), grafts not accepted for transplantation. RESULTS: No differences in donor and recipient characteristics were found among the groups. The mean values of cTnI (0.36+/-0.88 microg/L, 4.45+/-3.28 microg/L, and 3.02+/-7.88 micog/L, respectively) and cTnT (0.016+/-0.029 microg/L, 0.134+/-0.114 microg/L, and 0.123+/-0.245 microg/L, respectively) were lower in group I when compared with groups II or III (cTnI: P<0.0001, P=0.018; cTnT: P<0.0001, P=0.012). The cTnI value was higher in group II compared with group III (P=0.023). The cTnT values were similar in groups II and III. A cTnI value >1.6 microg/L as a predictor of early graft failure had a specificity of 94%, and a cTnT value of >0.1 microg/L had a specificity of 99%. The odds ratio for the development of acute graft failure after heart transplantation was 42.7 for donors with cTnI >1.6 microg/L and 56.9 for donors with cTnT >0.1 microg/L. No differences of myoglobin, CKMB activity, or CKMB/CK ratio were found among the groups. CONCLUSIONS: Significantly higher cTnI and cTnT values were found in peripheral blood at the time of explantation in donors of hearts with subsequently impaired graft function and in not accepted donors. cTnI and cTnT are useful as additional parameters for heart donor selection.

Adult↗
PubMed2001

Mechanical circulatory support for advanced heart failure: effect of patient selection on outcome.

BACKGROUND: Use of wearable left ventricular assist systems (LVAS) in the treatment of advanced heart failure has steadily increased since 1993, when these devices became generally available in Europe. The aim of this study was to identify in an unselected cohort of LVAS recipients those aspects of patient selection that have an impact on postimplant survival. METHODS AND RESULTS: Data were obtained from the Novacor European Registry. Between 1993 and 1999, 464 patients were implanted with the Novacor LVAS. The majority had idiopathic (60%) or ischemic (27%) cardiomyopathy; the median age at implant was 49 (16 to 75) years. The median support time was 100 days (4.1 years maximum). Forty-nine percent of the recipients were discharged from the hospital on LVAS; they spent 75% of their time out of the hospital. For a subset of 366 recipients, for whom a complete set of data was available, multivariate analysis revealed that the following preimplant conditions were independent risk factors for survival after LVAS implantation: respiratory failure associated with septicemia (odds ratio 11.2), right heart failure (odds ratio 3.2), age >65 years (odds ratio 3.01), acute postcardiotomy (odds ratio 1.8), and acute infarction (odds ratio 1.7). For patients without any of these factors, the 1-year survival after LVAS implantation including the posttransplantation period was 60%; for the combined group with at least 1 risk factor, it was 24%. CONCLUSIONS: Careful selection, specifically implantation before patients become moribund, and improvement of management may result in improved outcomes of LVAS treatment for advanced heart failure.

Adolescent↗
PubMed2001

New pulsatile bioreactor for fabrication of tissue-engineered patches.

To date, one approach to tissue engineering has been to develop in vitro conditions to ultimately fabricate functional cardiovascular structures prior to final implantation. In our current experiment, we developed a new pulsatile flow system that provides biochemical and biomechanical signals to regulate autologous patch-tissue development in vitro. The newly developed patch bioreactor is made of Plexiglas and is completely transparent (Mediport Kardiotechnik, Berlin). The bioreactor is connected to an air-driven respirator pump, and the cell culture medium continuously circulates through a closed-loop system. We thus developed a closed-loop, perfused bioreactor for long-term patch-tissue conditioning, which combines continuous, pulsatile perfusion and mechanical stimulation by periodically stretching the tissue-engineered patch constructs. By adjusting the stroke volume, the stroke rate, and the inspiration/expiration time of the ventilator, it allows various pulsatile flows and different levels of pressure. The whole system is a highly isolated cell culture setting, which provides a high level of sterility, gas supply, and fits into a standard humidified incubator. The bioreactor can be sterilized by ethylene oxide and assembled with a standard screwdriver. Our newly developed bioreactor provides optimal biomechanical and biodynamical stimuli for controlled tissue development and in vitro conditioning of an autologous tissue-engineered patch.

Biocompatible Materials↗
PubMed2001

Decreased plasma concentration of brain natriuretic peptide as a potential indicator of cardiac recovery in patients supported by mechanical circulatory assist systems.

OBJECTIVES: We sought to investigate the relationship between the plasma concentration of brain natriuretic peptide (BNP), echocardiographic findings and the clinical outcome of patients supported with ventricular assist devices (VADs) to determine the role of BNP as a predictor for cardiac recovery. BACKGROUND: Ventricular unloading in patients with end-stage heart failure supported by VADs may lead to myocardial recovery. The BNP is produced in the myocardium in response to chronic volume overload, but the effects on it of ventricular unloading by VADs are largely unknown. METHODS: Twenty-one patients diagnosed with nonischemic cardiomyopathy and supported by VADs were evaluated for echocardiographic data and blood chemistry including BNP. They were divided into patients who died while on mechanical support (group I; n = 9), patients who were transplanted (group II; n = 8) and patients who were successfully weaned off the system and did not require transplantation (group III; n = 4). RESULTS: Brain natriuretic peptide plasma concentrations decreased significantly after initiation of mechanical circulatory support (p = 0.017). Furthermore, the changes in BNP plasma concentrations showed a faster decrease to normal levels within the first week after implantation of the VAD in patients who were weaned off the system (group III) compared to patients in group I and group II. CONCLUSIONS: This study shows that ventricular unloading with VADs decreases BNP plasma concentrations in patients who suffer from end-stage heart failure. Furthermore, we hypothesize that an early decrease of BNP plasma concentration may be indicative of recovery of ventricular function during mechanical circulatory support.

Adolescent↗
PubMed2001

Plasmapheresis and cyclophosphamide in the treatment of humoral rejection after heart transplantation.

BACKGROUND: Clinical reports on humoral rejection after heart transplantation showed that these episodes were often more severe than those mediated through T lymphocytes and that the patient's prognosis was significantly worsened. METHODS: To evaluate the impact of plasmapheresis on the course of humoral rejection with hemodynamic compromise (HRHC) episodes, we retrospectively investigated the records of 1,108 heart transplant patients. All patients received triple-drug immunosuppression (cyclosporine a, azathioprine, prednisone) and cytolytic antibodies for induction. Between April 1986 and December 1990, HRHC episodes were treated with cortisone boli and cytolytic antibodies for at least 3 days (Group A). Between January 1991 and April 1999, HRHC episodes were treated with cortisone boli, cytolytic antibodies, and plasmapheresis for at least 3 days (Group B). All patients who survived their first HRHC episode received cyclophosphamide instead of azathioprine as maintenance immunosuppression. RESULTS: Altogether we observed 29 HRHC episodes. In 11 cases, no therapy could be administered or the therapy regimen did not correspond to either Protocol A or B. In the remaining 18 HRHC episodes, 7 episodes in 7 patients were treated without plasmapheresis (Group A), but only 2 patients survived, whereas in 11 HRHC episodes in 6 patients, therapy included plasmapheresis (Group B) and all patients survived (p = 0.002). Four of 6 patients who received cyclophosphamide after their first HRHC episode experienced at least 1 further HRHC episode. CONCLUSIONS: Plasmapheresis seems to improve outcomes in HRHC. However, cyclophosphamide as a maintenance immunosuppressive drug failed to prevent further humoral rejection episodes.

Adolescent↗
PubMed2001

Revascularization of the occluded right coronary artery during left ventricular assist device implantation.

A 62-year-old man with end-stage ischemic cardiomyopathy and left ventricular function of 20% was evaluated for heart transplantation. Cardiac catheterization revealed proximal occlusion of the dominant right coronary artery (RCA) with collateral blood flow and significant stenosis in the distal part, but no significant re-occlusions of the stented left coronary artery and no significant stenosis of the left circumflex artery. When the patient became catecholamine dependent, Novacor left ventricular assist device (LVAD) implantation, as a bridge to transplantation, was considered and the patient operated upon. To avoid ischemic right heart failure after LVAD implantation, a concomitant re-vascularization of the distal RCA was performed. The post-operative course was uneventful. Five weeks later, a control angiogram showed the patent bypass graft. The distal stenosis of the RCA was treated successfully with dilation and stent implantation. The patient is presently in stable condition on LVAD and awaits transplantation as an outpatient.

Angioplasty, Balloon, Coronary↗
PubMed2001

Postoperative course of S-100B protein and neuron-specific enolase in patients after implantation of continuous and pulsatile flow LVADs.

BACKGROUND: In the early post-operative period after implantation of a continuous flow left ventricular assist device (LVAD) a non-pulsatile flow occurs. We compared the post-operative time-courses of protein S-100B (S100B) and neuron-specific enolase (NSE) as biochemical markers of brain injury in patients after implantation of a continuous flow LVAD and patients receiving a pulsatile flow LVAD. METHODS: Since 1998 the continuous flow DeBakey VAD has been implanted in 8 patients at our institution. For comparison purposes, a group of 7 consecutive patients in whom a pulsatile Novacor N100 LVAD was implanted were investigated. In both groups cardiopulmonary bypass (CPB) with cardiotomy suction was used. S100B and NSE were measured in serum pre-operatively, 4 hours after CPB, and on days 1, 3, 7, and 14 after implantation of the LVAD. A neurologic examination was performed pre-operatively and post-operatively on days 3 and 14. RESULTS: No differences were found between groups in pre-operative characteristics. The analysis of variance with repeated measurements for S-100B and NSE showed significant time effects (p = 0.004, p = 0.009, respectively) but no group effects (p = 0.06, p = 0.26, respectively) and no interaction between groups and time (p = 0.12, p = 0.48, respectively). The pre-operative serum level of S100B was significantly higher (p = 0.03) in the DeBakey VAD group. The pre-operative serum level of NSE was similar in the 2 groups (p = 0.7). In both groups there was a significant increase of S100B and NSE immediately after surgery (S100B: p = 0.006, p = 0.019; NSE: p = 0.01, p = 0.001). The values returned to pre-operative levels in the DeBakey VAD group on day 1 after implantation and in the Novacor group for S100B on day 3 and NSE on day 1. Post-operatively the mean values of S100B and NSE in the DeBakey VAD group compared with the Novacor group were significantly elevated only on day 3 (p = 0.005, p = 0.023).No neurologic complications were noted in patients with a continuous flow LVAD, whereas in the pulsatile LVAD group 2 patients presented neurologic abnormalities during the study period. CONCLUSIONS: The similar course of biochemical markers of brain damage in both groups may indicate that the non-pulsatile flow in the early post-operative period does not lead to increased brain injury or permeability of the brain blood barrier.Elevated levels of S100B and NSE in the post-operative period can be used as diagnostic markers of brain injury in patients after implantation of both types of LVAD.

Adult↗
PubMed2001

Ventricular assist device in severe heart failure: effects on cytokines, complement and body weight.

AIMS: Inflammatory and immune activation and body wasting are important features of end-stage chronic heart failure. It is not known whether restoration of cardiac output by assist device implantation can improve these abnormalities. METHODS: We studied 48 patients (39 males; age 45+/-2 years) with NYHA class IV heart failure. All patients underwent ventricular assist device implantation for end-stage heart failure as a bridge to cardiac transplantation. Plasma levels of tumour necrosis factor alpha, and its receptors, interleukin-6, elastase, activated complement, and soluble CD14 receptors were measured at the time of operation and in survivors at 1 week (n=46), 40 days (n=35) and 90 days (n=26). Follow-up was for a minimum of 1 year. RESULTS: One-year survival was 35% (95% CI: 22-49%). Body mass index was the only predictor of survival (body mass index >25 (n=16); survival 63 (39-86) %; body mass index <25 (n=32); survival 22 (7.5-36) %: P=0.003). Tumour necrosis factor alpha fell from 9.66+/-1.33 pg x ml(-1) to 4.2+/-1.0 at 1 week (P=0.008), but returned to pre-operative levels at 90 days. Interleukin-6, activated complement and elastase fell progressively to 40 days, but were rising at 90 days. There was no change in tumour necrosis factor receptor. There was a gradual rise in CD14 (3.99+/-0.15 microg x ml(-1) at baseline, 5.02+/-0.39 at 90 days, P=0.006). After surgery, body weight fell from 80+/-2 to 73+/-2 kg by 1 month (P<0.001) and to 72+/-2 kg at 90 days. CONCLUSIONS: Ventricular assist device implantation results in a short-term fall in tumour necrosis factor alpha and interleukin-6, but no change in CD14 or tumour necrosis factor receptor, suggesting that the pathophysiological process resulting in inflammation was not altered by left ventricular assist device implantation. Low body mass index is related to poor outcome after assist device implantation, and no weight gain.

Body Weight↗
PubMed2001

Outpatients on biventricular assist devices.

As waiting times for transplants have lengthened, long-term mechanical circulatory support (MCS) has become more common in patients who present with severe cardiogenic shock leading to multiorgan failure. With these patients, we used the biventricular assist device (BVAD, Berlin Heart). In this report, we will describe our 4 years of experience with 11 patients on a BVAD who were discharged home while awaiting transplantation. The 11 patients underwent BVAD implantation from 1997 to 2000. These were 2 women and 9 men. The mean support time was 382 days (range: 156 - 567). The indication for BVAD was cardiomyopathy--six dilated, one restrictive and four ischemic. These patients were monitored for infections, thromboembolic events, bleeding complications, and psychological effects during the time they spent at home. Our experience shows that all of the patients could leave hospital following sufficient training for dressings and anticoagulation after recovering completely from secondary organ dysfunction. The mean time period the patients spent at home was 48 days (range: 3 - 182) days. Seven patients (63 %) had to be readmitted to the hospital--due to transitory ischemic attacks in two cases, hemorrhoidal bleeding in one and wound infections in four cases. One patient died of a traumatic accident during sexual activity. The use of a BVAD is feasible for outpatient use as a bridge to transplantation. It ensures the survival of the patient, enables recovery from multiorgan failure and offers an acceptable quality of life.

Adult↗
PubMed2001

Heparin antibodies and thromboembolism in heparin-coated and noncoated ventricular assist devices.

OBJECTIVE: Coating of ventricular assist devices (VADs) with heparin improves the biocompatibility and may reduce the need for systemic anticoagulation. However, heparins are associated with the risk of formation of heparin/platelet factor 4 antibodies (HPF4/A) and the development of heparin-associated thromboemboli. We analyzed the occurrence of HPF4/A and thromboembolism in patients with heparin-coated and noncoated VADs. METHODS: One hundred patients were enrolled in the investigation. Fifty-seven received a heparin-coated (group 1) and 43 a noncoated (group 2) VAD. HPF4/A testing was performed before and 2 and 12 weeks after implantation by the heparin platelet factor 4 enzyme-linked immunosorbent assay. RESULTS: There was no significant difference in the occurrence of HPF4/A in the 2 groups (P =.102). Before the operation, 21 of the patients in group 1 had positive test responses and 25 in group 2. No patient had HPF4/A after termination of systemic heparinization. In group 1 there was no significant difference in the incidence of recurrent pump thromboses in patients who had positive test responses for HPF4/A (n = 11) when compared with those who had negative test responses (n = 9, P =.89). Twenty-one patients had HPF/A but no thromboembolism. However, all 22 patients who had thromboembolism had HPF4/A. CONCLUSIONS: Heparin coating of the VAD surface does not enhance the occurrence of HPF4/A-associated immunologic or thrombogenic reactions. However, the presence of these antibodies is strongly associated with an increased risk of thromboembolism in patients with a VAD.

Adolescent↗