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Biomedical subjects

M Loebe

Publications and source records attributed to M Loebe.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Heart transplantation--indications and results].

Heart transplantation has become a standard procedure in the treatment for irreversible heart failure. Criteria for both recipients and donors have been extended. One year survival now reaches 81%. In the immediate postoperative course patients are endangered by infection. In the long-term course coronary artery disease of the transplanted heart becomes the most serious problem. Alteration of liver and kidney function due to chronic medication as well as malignancies and hypertension also occur. In case of chronic transplant failure retransplantation may be indicated. Acute cardiac failure before transplantation nowerdays can be treated by mechanical circulatory assist devices.

Follow-Up Studies↗
PubMed1992

[Progress in heart transplantation].

Within the past 10 years, heart transplantation has become established as a standard procedure in heart surgery. Improvements in immunosuppressive therapy and diagnosis of graft rejection have been crucial. The criteria for transplantation have been broadened for recipients as well as for donors. Newborns, pediatric patients, diabetics, and patients with impaired renal function will no longer be excluded from transplantation due to improved postoperative therapy. Furthermore, progress has been made with assisted circulation. Patients with acute heart failure can now be bridged to transplantation.

Adult↗
PubMed1990

[Cytomegalovirus infection and coronary sclerosis after heart transplantation].

Serological tests for cytomegalovirus (CMV) after cardiac transplantation were performed at six to eight-week intervals on 26 patients (3 females and 23 males; mean age 46 [15-62] years) with angiographic or ultimately autopsy evidence of coronary atherosclerosis (group 1) and 24 patients (5 females and 19 males; mean age 45 [25-56] years) without coronary disease in the transplanted heart. A positive result meant an at least fourfold increase in CMV IgG titre, demonstration of CMV IgM or direct viral isolation from blood or other body fluid. In 20 patients of group 1 (77%) a CMV infection had occurred after the transplantation, but in only six patients (25%) in the group 2 (P less than 0.0001). These results are interpreted as demonstrating a relationship between CMV infection and rapidly progressive coronary atherosclerosis after cardiac transplantation.

Adolescent↗
PubMed1989

Heart transplantation in Berlin.

Since July 1983, our group experience with heart transplantation as a routine procedure now includes 346 patients. Predominant diagnosis was dilated cardiomyopathy (64%). The age range was 3 months to 68 years (mean 44.3 years). Immunosuppression has followed several evolving protocols and now emphasizes preoperative administration of cyclosporine A and quadruple immunosuppression with additional azathioprine, cortisone medication, and early postoperative cytolytic prophylaxis with rabbit ATG. We have accepted donor organs up to 55 years without coronary angiography and with very satisfying functional and late results. The diagnosis of rejection by endomyocardial biopsy has been supplemented by routine use of telemetric intramyocardial electrogram monitoring and M-mode echocardiography. Routine use of these methods has distinctly increased diagnostic safety. Eleven children between the ages of 3 months and 18 years have been transplanted with a 72% overall survival rate. Four children younger than age 8 have been followed with noninvasive methods for rejection diagnosis exclusively. A bridge to transplantation program was initiated in July 1987; 31 patients were bridged, 18 of whom could be transplanted. Thirteen patients were discharged after a mean posttransplant period of 31 days. Future development issues will include extension of donor heart criteria, noninvasive diagnosis of rejection, and increasing experience with mechanical bridging.

Adolescent↗
PubMed1989

Extended donor age in cardiac transplantation.

Approximately one third of brain-dead organ donors are above the age of 35 years. These donors have been used routinely for heart transplantation because the risks of compromised early graft function and potentially accelerated graft atherosclerosis remained nuclear. The increasing length of the waiting list and a 30% death rate of those on the waiting list for donor organs in our heart transplant program led to acceptance of donor hearts up to 54 years of age. Of a total number of 233 donor hearts, 74 were between 36 and 54 years old (group 2). These hearts were compared for early and chronic graft function with a group of 159 patients who received hearts from donors aged 1-35 years (group 1). All but three group 2 hearts were accepted without coronary angiography. Early postoperative graft function was sufficient in all 72 group 2 patients, whereas in group 1, early graft failure in nine (5.7%) patients led to death or required retransplantation. Forty-one patients in group 2 and 79 patients in group 1 were restudied at annual intervals between 1 and 4 years postoperatively by complete cardiac angiography. Mean late postoperative left and right ventricular ejection fractions were normal in both groups. Graft atherosclerosis was found in seven (8.9%) patients in group 1 and in four (9.8%) patients in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The carpal tunnel syndrome--a disease underlying Raynaud's phenomenon?

Forty patients with clinically and electromyographically proven carpal tunnel syndrome were examined for the frequency of concomitantly occurring Raynaud's phenomenon. The angiologic work-up was based on a detailed vascular history and examination, Doppler sonography to determine systolic digital artery pressures before and after exposure to the cold (10 degrees C for one minute), and thermoplate tests for recording heat convection of the hands at normal room temperature and measuring rewarming time after standardized cold exposure. Only 10% of the patients were found to have manifest Raynaud's phenomenon. The incidence was thus the same as in the general population. In addition, Raynaud's phenomenon and the carpal tunnel syndrome were poorly correlated with respect to their preliminary symptom appearances. Consequently, the carpal tunnel syndrome can no longer be regarded as a disease underlying Raynaud's phenomenon.

Adult↗
PubMed1988

[The role of surgery in the treatment of acute myocardial infarct].

The surgeon's role in the treatment of acute myocardial infarcts is limited to selected cases in which emergency revascularization can be performed with reasonable expectation for salvage of an ischemic, however, still viable myocardium. This goal can be achieved under optimal logistic conditions. At present the result of emergency revascularization can not be predicted with certainty due to the lack of diagnostic methods which would allow for instantaneous differentiation between ischemic and necrotic myocardium. Surgical techniques are established for infarct sequelae such as ventricular rupture, papillary muscle necrosis, and ventricular septal defect, however, the outcome of emergency operations in these instances is primarily determined by the duration and intensity of preoperative circulatory failure. Cardiac transplantation with or without temporary mechanical support or replacement appears to be the future treatment of choice in acute irreversible congestive heart failure and global ventricular impairment following myocardial infarction.

Coronary Artery Bypass↗
PubMedDate not supplied

Pathophysiologic role of contact activation in bleeding followed by thromboembolic complications after implantation of a ventricular assist device.

The time period after implantation of a ventricular assist device in patients with end-stage heart disease is complicated by hemorrhage in the early postoperative period and by thromboembolism in the later course. To investigate the pathophysiologic role of contact activation in 12 bridging patients (10 patients with a paracorporeal Berlin Heart [Berlin Heart GmbH, Berlin, Germany], 2 patients with an intracorporeal Novacor system [Novacor N100; Baxter, Oakland, CA]), hemostatic parameters were determined until heart transplantation or at least up to the 51st postoperative day. The following were observed: 1) In the early postoperative period, until day 15, levels of contact factors XI, XII, and prekallikrein were below normal, whereas levels of plasmin-a2-antiplasmin (PAP) complexes were elevated. Thrombin-antithrombin III (TAT) complexes, as well as platelet factor 4 and beta-thromboglobulin, significantly increased immediately after surgery. 2) In the later postoperative period, starting with the third postoperative week, an increase of factors XI, XII, and prekallikrein was observed. PAP and TAT complexes, as well as platelet factor 4 and beta-thromboglobulin, remained elevated. It is concluded that, in the early postoperative period, hemostasis is influenced mainly by an activation of the intrinsic contact system dependent fibrinolytic system with consumption of contact factors and increased levels of PAP complexes, whereas later system dependent fibrinolysis becomes less important, leading to a shift of the balance toward coagulation, with sustained prothrombin and platelet activation. This is in accord with the observed clinical complications (e.g., early postoperative bleeding, and thromboembolic events later on).

Adult↗
PubMedDate not supplied

Mechanical circulatory support for post cardiotomy cardiogenic shock in infants.

Eleven infants weighing 2.3 to 7.8 kg underwent mechanical circulatory support for post cardiotomy cardiogenic shock. Initiated pre-operatively in two patients, extracorporeal membrane oxygenation was used in a total of eight patients aged 6 days to 3 months in association with repair of cyanotic congenital heart disease with increased pulmonary blood flow or with a right sided obstructive lesion. Ventricular assist devices were used in three other patients: a centrifugal left ventricular assist device in Patient 1 (10 months, 5.7 kg) after repair of the anomalous left coronary artery, and a pneumatic biventricular assist device (stroke volume 12 ml) in Patient 2 (6 months, 7.0 kg) for cardiac arrest after closure of ventricular septal defect and in Patient 3 (10 months, 7.8 kg) for post transplant graft failure. Duration of extracorporeal membrane oxygenation duration ranged from 26 to 192 hr (mean, 88 hr). Three patients were weaned from extracorporeal membrane oxygenation and two survived. Two others were separated from extracorporeal membrane oxygenation because of bleeding, but both subsequently died. Patient 1 was weaned from the left ventricular assist device after 192 hr and discharged from the hospital. Support was discontinued after 45 hr in Patient 2 who exhibited irreversible brain damage. Patient 3 was weaned from a biventricular assist device after 174 hr, but suffered recurrent graft failure. Our results show that an appropriate circulatory support system should be selected according to the cardiac anatomy in infants.

Acute Kidney Injury↗
PubMedDate not supplied

Complement activation in patients undergoing mechanical circulatory support.

Contact of blood with artificial surfaces activates pro-inflammatory responses and the complement cascade. This may have broad implications on the post implantation fate of patients needing mechanical circulatory support. Therefore, we investigated the course and prognostic value of complement factors C3a and C5a in 66 patients supported with pulsatile ventricular assist devices. All patients were in severe cardiogenic shock, i.e., catecholamine dependent and in the intensive care unit, before implementation of mechanical circulatory support. Isolated left ventricular support (Novacor [Oakland, CA] or Thermo Cardiosystems, Inc. [TCI; Woburn, MA]) was used in 28 patients, and biventricular support (Berlin Heart [Mediport, Berlin, Germany]) in 38 patients. Before initiation of mechanical circulatory support, no statistically significant differences in C3a or C5a between surviving and nonsurviving patients with left ventricular assist devices (LVADs) were found. Patients with biventricular assist devices (BVADs) had significantly higher C3a (804 +/- 364 ng/L) levels than patients with LVADs (536 +/- 204 ng/L, p = 0.02) before mechanical circulatory support. Only C5a, only in the BVAD group, was able to predict patients' post implantation course before implantation of a ventricular assist device (p = 0.02). Three weeks after initiation of mechanical circulatory support, complement factors remained increased in all groups. There was no difference, however, in complement activation between patients with LVADs and those with BVADs. Patients not reaching transplantation had significantly higher C3a levels at this point than those successfully supported (p = 0.007). The degree of complement activation mainly depends on the severity of cardiogenic shock before initiation of mechanical circulatory support, and not on the device used. Patients with extremely high levels of complement activation before implantation of the device could be saved with BVAD rather than LVAD support. Patients who continued to have highly elevated complement levels 3 weeks after initiation of mechanical circulatory support had unfavorable prognoses. Complement activation indicates the severity of cardiogenic shock before implementation of mechanical circulatory support and the degree of recovery from secondary organ dysfunction while on the device. It is fairly independent of the system used for mechanical circulatory support, and therefore can be applied to predict patients' post implantation course and outcome.

Adolescent↗
PubMedDate not supplied

Prevalence and persistence of heparin/platelet factor 4 antibodies in patients with heparin coated and noncoated ventricular assist devices.

Thromboembolism is a major complication in patients with ventricular assist devices (VAD). Anticoagulation with heparin, coumarin, and anti-platelet agents, particularly the development of biocompatible surfaces such as inner pseudo-endothelial layers or a coating with heparin, are intended to reduce these complications. However, the administration of heparin can lead to heparin induced thrombocytopenia type II (HIT II). Predominantly heparin/platelet factor 4 (HPF4) antibodies are responsible for the development of HIT II. The goal of the present investigation was to assess the prevalence of these antibodies in patients with heparin coated and noncoated VADs. Fifty-five patients were enrolled in the investigation. A heparin coated system was implanted in 30 patients, and a noncoated system was implanted in 25 patients. Antibodies were evaluated before, on days 7 and 14, and 3 months after implantation. Testing was performed with the Heparin/Platelet factor 4 enzyme-linked immunosorbent assay (ELISA) (Stago, France). In 40 of the 55 patients, the formation of HPF4 antibodies was observed (73%). In 35 of these patients (88%), HPF4 antibodies were present before surgery. There were no differences between the groups. In 11 patients (equal from both groups), the antibodies disappeared after termination of systemic heparinization. We conclude that in a rather high percentage of patients with VADs HPF4 antibodies are found. This finding may be explained by the repetitive and prolonged exposure of these patients to heparin. Immobilized heparin, as presently used in the carmeda coating, seems not to influence the formation and persistence of HPF4 antibodies. Further studies will have to prove whether HPF4 antibodies contribute to thromboembolic complications in these patients.

Adult↗
PubMedDate not supplied

Transcranial detection of microembolic signals in patients with a novel nonpulsatile implantable LVAD.

Mechanical ventricular assist devices (VAD) have become an accepted therapy for the support of patients in severe heart failure. With the devices presently available, the incidence of thromboembolic complications is high. Since November 1998, we have used the DeBakey VAD (MicroMed, Inc., Woodlands, TX). To detect the effect of this VAD on the appearance of microthrombi or bubbles from cavitation, we measured Microembolic Signals (MES) with transcranial Doppler in patients after the implantation of the DeBakey VAD. Transcranial Doppler studies were performed with the MULTI-DOP X4 device with two 2 MHz probes (for the left and right middle cranial arteries [MCA]) in five patients preoperatively and during 10 weeks after VAD implantation. Both MCAs were monitored simultaneously for 60 minutes in 10 sessions in each patient. The detection and analysis of MES was performed in accordance with the technique and criteria described by the international consensus group. No MES were noted during the study period in four patients. In one patient with preoperatively noted MES the prevalence of MES postoperatively was 50%. The high speed rotating impeller of the DeBakey VAD did not produce any detectable microthrombi or bubbles from cavitation effects.

Adult↗
PubMedDate not supplied

Inflammatory response after implantation of a left ventricular assist device: comparison between the axial flow MicroMed DeBakey VAD and the pulsatile Novacor device.

The implantation of a ventricular assist device (VAD) is associated with a stimulation of the inflammatory system. We compared changes in the inflammatory response after implantation of a pulsatile Novacor left (L) VAD and the axial flow MicroMed DeBakey VAD. Six consecutive patients after implantation of a Novacor LVAD (NC) and six patients after implantation of a MicroMed DeBakey VAD (MD) were included in the investigation. Patients received LVADs for medically non treatable end-stage heart failure. Tumor necrosis factor alpha (TNF), C3a, C5a, interleukin 6 (IL-6), and neutrophil elastase were measured twice a week over a period of 3 months after implantation of the device. All tests were performed with an enzyme-linked immunosorbent assay. There was no significant difference in the clinical course of the two groups. All inflammatory parameters were elevated in both groups during the entire period of the investigation. There was no difference in TNF, polynuclear leukocyte elastase, or C3a levels between the two groups; however, IL-6 (NC: 23.6+/-37.6 pg/ml vs. MD: 63+/-114 pg/ml, p < 0.001) and C5a (NC: 708+/-352 microg/L vs. MD: 1,745+/-1,305 microg/L, p < 0.001) were increased significantly more in patients following implantation of the axial flow MicroMed DeBakey VAD. Compared with the pulsatile Novacor device, the implantation of the axial flow MicroMed DeBakey LVAD seems to be associated with an increased stimulation of one part of the inflammatory system. Further investigations are necessary for evaluation of the pathophysiologic mechanism and clinical implications of these findings.

Adult↗
PubMedDate not supplied

Autologous plasma and platelet sequestration at the beginning of cardiopulmonary bypass: a pilot investigation in five patients undergoing extended vascular surgery in deep hypothermia.

Platelet dysfunction and loss of procoagulants and platelets leads to impaired hemostasis after cardiopulmonary bypass (CPB). Preoperative platelet sequestration delays surgery, and the large volume shifts, necessary to harvest therapeutically effective components, may be associated with hemodynamic instability. We performed platelet and plasma sequestration after the initiation of CPB during the cooling period in patients undergoing surgery in deep hypothermic cardiac arrest. Five patients who underwent major vascular surgery in deep hypothermia were enrolled in this pilot study. Platelet and plasma sequestration was performed during cooling with the CATS cell saver using the plasma sequestration set. Before processing, 2 x 1,000 ml of blood were concentrated by means of hemofiltration to reduce dilution effects of CPB. The autologous platelet concentrates were rotated at 24 degrees C, and the plasma was stored at room temperature. The harvested plasma and platelets were re-transfused during modified ultrafiltration after CPB. Platelet count, 20 mmol/L ADP stimulated platelet aggregation, and fibrinogen levels were measured preoperatively in the harvested material and in patient blood before and after transfusion. A heparinase thromboelastogram (TEG) was performed preoperatively before and after re-transfusion. There was a significant increase in the ADP stimulated platelet aggregation, platelet count, fibrinogen level, and maximum amplitude of the TEG after re-transfusion of the harvested material. No patient needed transfusion of fresh frozen plasma or random donor platelet concentrates. No patient needed re-exploration due to hemorrhage. The data presented provide evidence that autologous plasma and platelet sequestration during CPB initiation is effective. The harvested material reveals a high platelet count and fibrinogen level and preserves functional integrity.

Aged↗
PubMedDate not supplied

Predictors of survival 1 hour after implantation of an intra-aortic balloon pump in cardiac surgery.

From July 1996 to March 2000, 391 patients with intraoperative cardiac low-output syndrome who underwent surgery with heart-lung bypass and had an intra-aortic balloon pump (IABP) implanted were analyzed in a prospective study. Of these 391 patients, 153 (39%) were operated on in an emergency situation, and 238 (61%) patients had elective surgeries. The perioperative mortality was 34% (133 patients). Clinical parameters were analyzed 1 hour after IABP support began. Statistical multivariate analysis showed that patients with an adrenaline requirement higher than 0.5 microg/kg/min, a left atrial pressure higher than 15 mmHg, output of less than 100 mL/hour, and mixed venous saturation (SvQ2) of less than 60% had poor outcomes. Using this data, we developed an IABP score to predict survival early after IABP implantation in cardiac surgery. We conclude that the success or failure of perioperative IABP support can be predicted early after implantation of the balloon pump. In patients with low-output syndrome despite IABP support, implantation of a ventricular assist system should be considered.

Aged↗
PubMedDate not supplied

Role of cytomegalovirus infection in the development of coronary artery disease in the transplanted heart.

In heart transplantation, accelerated graft arteriosclerosis leading to late postoperative graft failure is still an unsolved problem, and its pathogenesis is poorly understood. The existence of multiple underlying mechanisms has been discussed without conclusive results. In kidney transplantation, a negative influence of cytomegalovirus infection on long-term graft function and patient survival could be demonstrated. To evaluate the role of this infection on the incidence of coronary artery disease in the transplanted heart, we have analyzed the cytomegalovirus serostatus in 38 long-term survivors of orthotopic heart transplantation. In 14 patients (group A) graft arteriosclerosis was diagnosed by means of coronary angiography. In 24 patients (group B) the coronary vessels showed no pathologic findings. In 10 patients (71%) of group A serologic study showed evidence of cytomegalovirus infection, whereas only five patients (24%) of group B revealed cytomegalovirus infection. In two further patients of this group herpes zoster infection occurred (p less than 0.0001). Cytomegalovirus infection seems to be an important factor in the development of accelerated graft arteriosclerosis in the transplanted heart.

Adult↗