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Biomedical subjects

M Loebe

Publications and source records attributed to M Loebe.

At least 19 recordsLinked to original sources
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

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

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↗
PubMed2001

Anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and renal impairment using heparin and the platelet glycoprotein IIb-IIIa antagonist tirofiban.

BACKGROUND: Patients with heparin-induced thrombocytopenia type II require an alternative to standard heparin anticoagulation. However, in patients with renal impairment, anticoagulation during cardiopulmonary bypass with agents such as danaparoid sodium or r-hirudin are associated with hemorrhage. Anticoagulation with unfractionated heparins combined with prostacyclin, a potent platelet aggregation inhibitor, is associated with severe hypotension. The authors investigated a new concept using unfractionated heparins after platelet inhibition with the short-acting platelet glycoprotein IIb-IIIa antagonist tirofiban. METHODS: Ten patients with heparin-induced thrombocytopenia type II and renal impairment were enrolled in the investigation. All had heparin-induced thrombocytopenia type II antibodies present as proved by the heparin-induced platelet aggregation assay, the heparin-platelet factor 4 enzyme-linked immunosorbent assay, or both. In all patients, preoperative anticoagulation to an activated partial thromboplastin time of 40-60 s was performed with r-hirudin. Anticoagulation during cardiopulmonary bypass was achieved with a bolus of 400 IU/kg unfractionated heparins after a bolus of tirofiban 10 microg/kg followed by an infusion of tirofiban at a rate of 0.15 microg x kg(-1) x min(-1) until 1 h before conclusion of cardiopulmonary bypass. Additional unfractionated heparins were only administered if activated clotting time decreased below 480 s. Coagulation was monitored by a abciximab-modified TEG and the adenosine diphosphate-stimulated (20 microm) platelet aggregometry. D-dimer concentrations, as a marker of venous thromboembolism, were measured before and 12, 24, and 48 h after surgery. Postoperative antithrombotic therapy was started immediately with r-hirudin to anticoagulation to an activated partial thromboplastin time of 40-60 s. RESULTS: The postoperative blood loss ranged from 110 to 520 ml. No patient needed reexploration. In no patient was there clinical evidence of thrombosis or embolism in the postoperative period or of a critical increase of the D-dimer concentrations, suggesting venous thromboembolism. Transfusion of platelets was necessary in only two patients. CONCLUSIONS: The protocol is easy to perform and no increased postoperative bleeding and no thromboembolic complications occurred. The combination of unfractionated heparins and tirofiban may be an alternative to other anticoagulation strategies in patients with heparin-induced thrombocytopenia.

Adult↗
PubMed2000

Pulsatile flow in patients with a novel nonpulsatile implantable ventricular assist device.

BACKGROUND: Ventricular assist devices (VADs) are an accepted therapy for patients with end-stage heart failure. The implantable devices that are available produce a pulsatile flow and are very large. In 6 patients, beginning in November 1998, we started to use the continuous-flow implantable DeBakey VAD device, which weighs 93 g. To detect the flow in peripheral vessels, we measured transcranial Doppler signals in patients after implantation. METHODS AND RESULTS: Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2-MHz probes (for the middle cranial arteries) in 4 patients for up to 12 weeks twice weekly after implantation. The blood velocity was measured, and the pulsation index (PI) calculated. The measured pump flow and rotations per minute were registered. The preoperative echocardiographic assessment values were compared with those acquired 6 weeks after implantation. The PI increased continually in all patients after VAD implantation, left ventricular (LV) ejection fraction did not improve, but right ventricular (RV) ejection fraction after implantation improved compared with preoperative values. The LV end-diastolic diameter after implantation decreased between 11% and 46% intraindividually. There was no correlation between PI and blood pressure or, except in 1 patient, between PI and blood flow through the VAD. CONCLUSIONS: The DeBakey VAD unloads the LV, which leads to a decrease in LV end-diastolic LV diameter and to the restoration of RV function. The unloaded LV and partially recovered RV provide a nearly physiological pulsatile flow despite the continuous flow of the VAD. Pulsatility is independent of peripheral vascular resistance. The first clinical experience with the DeBakey VAD was positive and has resulted in its continued use.

Adult↗
PubMed2000

[Artificial heart in terminal stage of dilated cardiomyopathy in childhood].

In children with dilated cardiomyopathy the disease may progress so rapidly that they die during the waiting period before a suitable donor organ is found. Fifteen children of 4 months to 15 years of age had been in congestive heart failure with multiorgan failure due to dilated cardiomyopathy, where intensive medical treatment had failed. After resuscitation, a miniaturized pulsatile ventricular assist device for the mechanical replacement of heart function was implanted. The biventricular assist device ("Berlin Heart") consists of two extracorporeal pneumatically driven polyurethane blood pumps, with a multi-layer flexible membrane that separates a blood and an air chamber. Four silicon cannulae connect the blood pumps to the patient. A three-leaflet valve prevents blood reflux. The pumps are driven by a pulsatile electropneumatic system. In 12 of the 15 children the bridging to transplantation was successful with a support time of 1 to 98 days (mean 24 days). Nine of them were extubated and mobilized while assisted. Three children died during the support time due to hemorrhage, sepsis, and pulmonary failure. In addition, there was one infarction of the arteria cerebri media. To date seven of the transplanted children are in good condition on follow-up. The beneficial effects of ventricular assist device use are well known in adult patients and with special devices it can be transferred to infants and children in whom longer need for support is anticipated. Even in small infants it is an effective method for bridging to cardiac transplantation.

Adolescent↗
PubMed2000

Pseudoaneurysm of the outflow graft in a patient with Novacor N100 LVAD system.

Six months after implantation of a wearable Novacor N100 left ventricular assist device, a 47-year-old patient developed a swelling that overlay the body of sternum. Computed tomographic scan of the chest revealed a pseudoaneurysm of the Novacor outflow graft. The patient was taken back to surgery and the diagnosis was confirmed at operation. Repair was performed by direct sutures via right anterolateral thoracotomy, under deep hypothermia and low flow technique. The postoperative course was uneventful.

Aneurysm, False↗
PubMed2000

Alterations in coagulation after implantation of a pulsatile Novacor LVAD and the axial flow MicroMed DeBakey LVAD.

BACKGROUND: The MicroMed DeBakey left ventricular assist device (LVAD) is a chamber and valveless axial flow blood pump. We investigated parameters of the coagulation system in patients after implantation of the axial flow LVAD and patients following implantation of a pulsatile Novacor LVAD. METHODS: Six consecutive patients of both groups were investigated over a period of 6 weeks after implantation. beta-Thromboglobulin, platelet factor 4, factor XIIa, thrombin/antithrombin complexes, plasmin/alpha2-antiplasmin complexes, and D-Dimer levels were measured. RESULTS: With the exception of the plasmin/alpha2-antiplasmin levels in the Novacor group, all parameters were elevated in both groups. The levels of beta-thromboglobulin, platelet factor 4, factor XIIa, and plasmin/alpha2-antiplasmin were significantly increased in the axial flow LVAD group. CONCLUSIONS: The axial flow LVAD strongly influences the systems of contact activation and fibrinolysis. The elevation of platelet proteins appears to follow platelet damage. Although no thromboembolic events were observed in both groups, elevation of thrombin/antithrombin complexes provides convincing evidence of an increased activation of the coagulation system and the concomitant risk for the development of thromboembolism.

Adult↗
PubMed2000

Cardiopulmonary bypass in a patient with heparin-induced thrombocytopenia II and impaired renal function using heparin and the platelet GP IIb/IIIa inhibitor tirofiban as anticoagulant.

In a patient with heparin-induced thrombocytopenia II and impaired renal function, anticoagulation during cardiopulmonary bypass was successfully performed by the use of unfractionated heparin and the platelet glycoprotein IIb/IIIa inhibitor tirofiban. Postoperative antithrombotic therapy with recombinant hirudin was immediately initiated. This regimen for anticoagulation for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia II appears to be particularly appropriate for patients with impaired renal function or for hospitals without special experience with other alternative anticoagulation strategies.

Cardiopulmonary Bypass↗
PubMed2000

Tricuspid valve dysfunction and surgery after orthotopic cardiac transplantation.

OBJECTIVE: The study examines the prevalence of tricuspid regurgitation and biopsy-induced flail tricuspid leaflets after orthotopic heart transplantation and evaluates the results of the tricuspid valve surgery. METHODS: By a computerized search of the databases 647 of 889 patients who survived heart transplantation for more than 30 days were identified for this study. The primary tool for rejection monitoring in our institution is the daily observation of intramyocardial ECG (IMEG) based on day-by-day changes of the maximal QRS complex amplitude. Endomyocardial biopsy with 45-cm-long sheath bioptome was performed only in doubtful IMEG and echocardiographic data and at times of annual routine heart catheterization. Tricuspid regurgitation was diagnosed clinically and by echocardiography as mild, moderate and severe. Eleven patients received prosthetic valve replacements (four bioprostheses and seven mechanical valves) and six patients underwent valve reconstruction. The choice of xenograft valve was dictated by the condition of renal function. Patient survival and incidence of tricuspid regurgitation and freedom from operation for severe tricuspid regurgitation were analyzed with Kaplan-Meier method. RESULTS: The prevalence of tricuspid regurgitation was 20.1%. Mild and moderate tricuspid regurgitation was seen in 14.5 and 3.1% of the patients, respectively, who were responsive to medical therapy and remained clinically stable in NYHA class I-II. Severe tricuspid regurgitation was seen in 16 (2.5%) patients who presented signs of an acute right heart dysfunction. Tricuspid valve pathology at operation revealed biopsy-induced rupture of the Chordae tendineae at various valve segments mostly the anterior and posterior leaflets. There was one hospital death (<30 day) and five late deaths due to infection, arrhythmia and trauma and no procedural-related or directly cardiac related death. Ten patients (62.5%) are alive at a mean follow-up time of 29.9 months (range 4-81 months) and nine survivors are in NYHA class I-II and one in class III. CONCLUSIONS: Severe tricuspid regurgitation in transplanted hearts is associated mainly with biopsy-induced injury or endocarditis. Other regimes of rejection monitoring may help to eliminate this complication. Apart from our preference of valve repair, the choice of valve substitute may be influenced by the presence or the prospect of chronic renal failure. Heart transplant patients can safely undergo valve surgery with acceptable mortality, low morbidity and excellent intermediate-term clinical results. Mild to moderate functional tricuspid regurgitation is responsive to medical therapy and non-progressive and occur in 17.6% of orthotopic transplanted hearts without having a detrimental effect on the right ventricular performance.

Aged↗
PubMed2000

Medium-term results of heart transplantation using older donor organs.

BACKGROUND: Donor heart shortage has necessitated the expansion of the donor pool by the use of older hearts. PATIENTS AND METHODS: In a 13-year period, 1,070 heart transplants were performed in 1,035 adults at the German Heart Institute Berlin. We divided the patients into 3 groups: Group I, donor age <35 years (n = 524); Group II, donor age 35 to 50 years (n = 379); Group III, donor age >50 years (n = 167). We analyzed post-operative mortality (up to 30 days), cumulative survival rates, cardiac dependent morbidity, and changes in the left/right ventricular ejection fraction as well as freedom from cytomegalovirus infection and freedom from acute rejection episodes grade >/= 2 (International Society for Heart and Lung Transplantation). We also calculated the rate of cardiac interventions per patient in the groups. RESULTS: Recipients in Group III were significantly older, compared with Groups I and II. The post-operative mortality was 16.8% in Group I, 29.8% in Group II, and 23.4% in Group III. The differences were significant (p = 0. 00001) between Group I and Group II. The long-term cumulative survival rates were significantly better in Group I when compared with Groups II and III (p < 0.00001, p = 0.014), but it did not differ between Groups II and III (p = 0.18). However, cardiac morbidity in Groups I and II was significantly lower when compared with Group III (p = 0.0009, p = 0.037). Mean left and right ventricular ejection fraction was >55% and did not significantly change in groups for up to 10 years. Freedom from cytomegalovirus infection was not significantly different between Groups II and III (p = 0.09). Significantly fewer percutaneous transluminal coronary angioplasties were performed in Group I, but comparable numbers were carried out in Groups II and III (p = 0.53). For retransplantation a similar situation occurred. CONCLUSION: We did not find significant differences in the mid-term follow-up between patients who received hearts from 35- to 50-year-old donors and from those who had received hearts from donors >50 years, despite increased cardiac morbidity in Group III. Close monitoring of the coronary situation after heart transplantation and expanded indications for revascularization in Group III makes heart transplantation with older hearts a suitable option to save the lives of patients in end-stage heart failure.

Adult↗
PubMed2000

Surgical treatment of active infective aortic valve endocarditis with associated periannular abscess--11 year results.

AIMS: The aim of the study was to evaluate the long-term results of allograft and prosthetic valve replacement in the treatment of infective aortic valve endocarditis with periannular abscess. METHODS: Between March 1988 and March 1996, 65 patients underwent surgery for active aortic valve endocarditis and paravalvular abscess. The indications for surgery were congestive heart failure, systemic emboli and atrioventricular block III. The pre-operative evaluation was performed with transoesophageal echocardiography. Aortic valve replacement was performed with allografts in 47 cases, with mechanical valves in 15, and bioprosthetic valves in three cases. All patients with total ventricular-aortic dehiscence and prosthetic valve endocarditis were treated with allografts. RESULTS: The 30-day mortality rate was 23.5% in the prosthetic group, when compared with 8.5% in the patients treated with allografts. The rate of recurrent valve infections during the 11-year follow-up period was 27.1% in the prosthetic group and 3.2% in the allograft group. The actuarial 11-year survival rate was 82.1% in the allograft group and 64.7% in the prosthetic group. CONCLUSION: Aortic allografts are an effective treatment for infective aortic valve endocarditis with associated periannular abscess. The operative mortality and recurrent infection rates are lower than in the prosthetic group, resulting in a significantly higher survival rate. Diagnosis and surgical management of these cases should be based on pre-operative transoesophageal echocardiography.

Abscess↗