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Biomedical subjects

H Warnecke

Publications and source records attributed to H Warnecke.

At least 19 recordsLinked to original sources
PubMed1999

Routine minimal invasive vein harvesting reduces postoperative morbidity in cardiac bypass procedures. Clinical report of 1400 patients.

OBJECTIVE: Minimal invasive endoscopic vein harvesting has not gained widespread acceptance although potential improvements in wound healing and patient comfort are undebatable. The main objections to routine application have been impaired graft quality and prolonged operation time. The feasibility of introducing the minimal invasive approach to vein harvesting into a high volume cardiac bypass surgery program was to be investigated in 1400 patients. METHODS: Our preferred technique is based on standard videoscopic equipment for endoscopic surgery. No disposables are used. The subcutaneous tissue above the saphenous vein is tunnelled by exclusively sharp dissection. No shear stresses are applied to the vein graft or its side branches. Side branches are closed by clips or bipolar coagulation. The differences between endoscopic and conventional surgical vein harvesting with regard to operation time, graft quality, wound healing disturbances and postoperative pain were compared in two groups of 300 concurrently operated patients. Subsequently, a further 1100 patients underwent endoscopic vein harvesting, giving a total experience of 1400 endoscopic procedures. RESULTS: After a learning curve of approximately 100 procedures for an experienced surgeon, harvesting time using minimal invasive techniques was 16 +/- 4 min/graft vs. 10 +/- 2 min for the conventional technique (P < 0.01). Severe wound healing disturbances requiring re-intervention were observed in 0.1% following endoscopic harvesting, moderate wound healing disturbances were observed in 1.7% of patients. By comparison, conventional harvesting led to severe wound healing disturbances in 5% and to moderate disturbances in 8% (P < 0.05). Incidence of peri-operative myocardial infarction as an indirect measure of graft quality was 1.7% with endoscopic vs. 2.3% (n.s.) with conventional technique. Early postoperative mobilisation was faster, pain and need of analgesics were distinctly reduced in patients with endoscopic harvesting. Overall operation time was not significantly prolonged by the described technique. CONCLUSIONS: Minimal invasive endoscopic vein harvesting can be developed into a routine procedure resulting in a lower incidence of wound complications, less postoperative pain and much superior cosmetic results. Graft quality appears to be comparable to standard saphenectomy. There is, however, a higher demand of surgical training and expertise.

Aged↗
PubMed1998

Daily noninvasive rejection monitoring improves long-term survival in pediatric heart transplantation.

BACKGROUND: Acute rejection episodes and transplant vasculopathy (TVP) account for most of the late deaths after heart transplantation in both adults and children. Accumulating evidence indicates that fatal acute rejection and TVP are related to unrecognized and untreated early and ongoing acute rejection. Day-by-day surveillance of the heart and prompt treatment of any rejection may yield improved long-term survival. METHODS: In almost all patients having transplantation at our institution (978 patients since 1986), the intramyocardial electrogram (IMEG) was recorded routinely every day through a telemetry pacemaker and transmitted to our center by telephone modem. Earlier studies showed a substantial voltage drop in the IMEG QRS complex is highly indicative of acute rejection, including humoral rejection. In this study, we reviewed the data from 69 pediatric patients up to 16 years old for the incidence of acute rejection, TVP, and long-term outcome. Diagnostic endomyocardial biopsies were performed in only 10 patients, and recent coronary angiograms from 29 children were reviewed. RESULTS: In 50 children discharged after heart transplantation, IMEG surveillance data for a mean of 2.9 years indicated 72 acute rejection episodes. During follow-up of 1 month to 10.5 years (mean follow-up, 4.4 years), 2 patients died late of causes unrelated to either rejection or TVP. Another patient died of rejection during unrecognized underimmunosuppression nearly 8 years after transplantation and nearly 31/2 years after discontinuing IMEG recordings. Two patients without IMEG recording died of acute rejection or late TVP. In 1 patient, moderate TVP was seen on an angiogram after 41/2 years (incidence, 2.0%; 5-year incidence, 5.6%). CONCLUSIONS: Daily recording of the IMEG can reliably detect early stages of acute rejection episodes, and immediate rejection treatment seems to keep the incidence of TVP low. The IMEG appears better than all the other rejection monitoring protocols currently in use.

Acute Disease↗
PubMed1998

Percutaneous dilatational tracheostomy done early after cardiac surgery--outcome and incidence of mediastinitis.

During November 95 to April 97, 45 percutaneous dilatational tracheostomies were performed in a nonselected patient series of 2788 open cardiac surgery cases. Tracheostomy was performed as early as the 2nd postoperative day (median: 6th day), when extubation was not foreseen within the next few days. Duration of intubation was 13 days (mean). We observed 6 complications in 5 patients (13.3%), namely bleeding, misplacement of the tube, subcutaneous emphysema, and superficial infection of the tracheostoma. Mediastinitis and wound infection of the sternal wound did not occur in any single case. There was no death due to tracheostomy. Clinically evident tracheal stenosis and inadequate granulation of the stoma were not observed after extubation. In our opinion, percutaneous dilatational tracheostomy is justifiable, shows good results, and entails minimal risk if done early after cardiac surgery, and it is also superior to standard surgical tracheostomy. Increased incidence of mediastinitis was not seen.

Adult↗
PubMed1998

Treatment of humoral rejection after heart transplantation.

BACKGROUND: Until a few years ago, the incidence of humoral rejection after heart transplantation was underestimated. These episodes were frequently very aggressive and often fatal, because the maintenance and emergency immunosuppression available at the time only inadequately covered the humoral branch of the immune response. In spite of individual case reports, the effects of blood purification procedures or cyclophosphamide in this situation can only be insufficiently estimated. METHODS: To evaluate this therapy concept, 20 dog-lymphocyte-antigen-matched dogs underwent heterotopic neck-heart transplantation. Fourteen dogs underwent transplantation after having been previously sensitized through multiple skin transplantations, 6 dogs were not sensitized (control). The animals received an induction with 3x 250 mg prednisolone, as well as triple immunosuppression (cyclosporine, azathioprine, and cortisone). Biopsy (light microscopy, immunofluorescence), intramyocardial voltage, electric myocardial impedance (>200 kHz, <10 kHz), and echocardiographic (left ventricular wall thickness, diastolic relaxation velocity) examinations were performed daily to monitor rejection. Rejection therapy was continued for 3 days according to the following regimen: apheresis, cortisone boluses (CB), and cyclophosphamide in group A1 (n = 4), apheresis and CB without cyclophosphamide in group A2 (n = 4), and CB only in group C (n = 6). The subsequent course under triple immunosuppression was then observed. RESULTS: In the sensitized animals the onset of severe humoral rejection on the fifth day deteriorated cardiac function down to 75% (70% to 80%) of the initial values. In groups A1 and A2, apheresis resulted in recovery to near-control values (89% to 94%) within two hours, and indeed to complete recovery (97% to 101%) after the second apheresis, that is, within 1 day. In group C recovery was delayed (2 days) and incomplete (84% to 91 %). After therapy was discontinued, rejection-related functional deterioration recurred immediately in group C, and from 2 to 3 days after apheresis, regardless of whether cyclophosphamide therapy was performed (group A1) or not (group A2). In the control group all animals showed a rejection-free posttransplantation course. CONCLUSIONS: By diluting inflammatory mediators, apheresis leads to a rapid improvement in cardiac function during severe humoral rejection after head transplantation. Neither apheresis nor cyclophosphamide therapy are able to have an immediate positive influence on the activation of the immune cascade and to prevent an ongoing rejection.

Animals↗
PubMed1997

Status of patients presently living 9 to 13 years after orthotopic heart transplantation.

BACKGROUND: Heart transplantation has a dramatic impact on both life expectancy and quality of life in patients with terminal heart failure. The aim of the study was to evaluate psychologic, social, occupational, and somatic status of patients living long-term, 9 to 13 years after orthotopic heart transplantation. PATIENTS AND METHODS: Seventy-seven of 182 patients who received transplants between July 1983 and January 1988 in Hannover (1983-1985; n = 69 patients) and Berlin (1986-1988; n = 113 patients) have survived up to now, 9 to 13 years after transplantation (mean, 10 years 4 months). The patients and their medical records (eg, cardiac catheter studies, echocardiography) were examined to assess their somatic status. Psychologic, social, and occupational status and quality of life data were assessed by combination of self-rating questionnaires (the Short Form Health Survey Questionnaire, Giessener Beschwerdebogen [the Giessen Subjective Complaints List], the Sickness Impact Profile, and the Hospital Anxiety and Depression Scale) and semistructured interviews. RESULTS: Ninety-one percent of the patients were in New York Heart Association functional class I (70%) or II (21%). The results of the psychologic investigation revealed a definite impact of the side effects of chronic immunosuppression; however, overall, the quality of life rating was within the normal range. Sixty-seven (86%) patients were married, 51 (66%) patients were retired, 17 (22%) worked full-time or part-time, and 9 (12%) were housewife or houseman. Four male patients have fathered five healthy children 1 to 10 years after the transplantation. More than 75% of the patients had normal systolic ventricular function (mean left ventricular ejection fraction, 0.63). Coronary angiograms were normal or with minor wall irregularities in 86% (n = 66 patients), and revealed severe obstructions in 14% (n = 11). Normal function of all valves was found in one-third of the patients, tricuspid valve incompetence was not found or was insignificant in 87% (n = 67 patients) and severe in 8% (n = 10). Six patients had undergone tricuspid valve replacement, invariably for structural valve defects attributable to biopsy injuries. Fifty-eight patients (75%) exhibited various degrees of compensated renal insufficiency, 7 of them were on chronic hemodialysis, and 2 patients have undergone kidney transplantation. Hepatic function was normal in 68% (n = 52) of the patients, and 1 patient has developed liver cirrhosis. Osteoporosis was diagnosed of the discrete form in 7 (9%) and of a significant degree in 24 patients (31%); 38.5% (n = 30) complained of symptoms of polyneuropathy. CONCLUSIONS: The patients surviving 9 to 13 years after orthotopic heart transplantation are mostly in good physical status, the quality of life is comparable to the general population, and only a few of them have significantly limited in their life style. They do show the substantial chronic side effects of long-term immunosuppression, remaining treatment-dependent for a lifetime.

Adolescent↗
PubMed1996

Mycotic aortic aneurysms after orthotopic heart transplantation: a three-case report and review of the literature.

Mycotic aortic aneurysm is a rare yet life-threatening complication after orthotopic heart transplantation. This article reviews three cases of mycotic aortic aneurysm in heart transplant recipients developing in the first year after heart transplantation. Excision of the aneurysm and in situ reconstruction of the ascending aorta were performed with a patch of glutaraldehyde-fixed pericardium or cryopreserved aortic allograft material as a patch or conduit replacement. These cases show that early diagnosis by computed tomographic scanning, surgical treatment, high-dose parenteral antibiotics, and close follow-up are essential for successful treatment.

Adult↗
PubMed1993

Intramyocardial electrogram recordings for diagnosis and therapy monitoring of cardiac allograft rejection.

The registration of intramyocardial ECG amplitudes (IMEG) is a non-invasive diagnostic method of monitoring cardiac allograft rejection. In order to detect possible sources of error IMEG signals were recorded in heterotopic neck hearts in ten beagle dogs. Immunosuppression was based on cyclosporin A. The rejection process was followed by IMEG registrations as well as by serial myocardial biopsies. Intramyocardial electrogram recordings were made via three unipolar and three bipolar leads obtained from screw-in electrodes in both ventricles and the apex of the allograft. A 10% voltage drop was used as an indicator of rejection. In four dogs, the first rejection episode was treated with methyl-prednisolone and the therapy's success was monitored by IMEG and repeat biopsy. At autopsy the histology of each electrode circumference was correlated with the corresponding IMEG. The average sensitivity of a single lead was not acceptable (unipolar: 28%, bipolar: 47%). When the voltages of different leads were summed up the sensitivity rose to 43% (3 x unipolar), 85% (3 x bipolar) and 100% (all leads). During rejection therapy the IMEG recovered within 24-48 h. We conclude that in moderate allograft rejection (grade 2/3a ISHT classification), the rejection-related changes of intramyocardial ECG voltage amplitude (IMEG) seem to follow a "focal pattern" similar to the histology. Therefore the recording of several, preferably bipolar, electrode configurations appears to enhance adequate diagnostic reliability.

Animals↗
PubMed1993

Survival predictors in patients with a left ventricular ejection fraction of 10-30% receiving a coronary bypass: analysis of preoperative variables.

A total of 224 patients with angina pectoris and a left ventricular ejection fraction in the range of 10-30% (mean 24.2%) underwent coronary artery bypass grafting between April 1986 and August 1991. These patients received a mean (s.d.) of 2.9 (0.3) aortocoronary vein grafts. The overall operative mortality rate was 8.9%. The 1-, 2- and 3-year survival rates were 87.7%, 86.7% and 85.2%, respectively. Analysis of operative risk factors showed that patients with an end-diastolic left ventricular pressure > 24 mmHg were significantly more at risk (mortality rate 20.0%, P < 0.05) than those with an end-diastolic left ventricular pressure < or = 24 mmHg (mortality rate 6.2%). Patients with a perioperative cardiac index < 2.5 l min-1m-2 had higher mortality (25.4%) than those with a cardiac index > or = 2.5 l min-1m-2 (mortality 1.9%, P < 0.001). The operative mortality rate of patients with a cardiac index < 2.5 l min-1m-2 and an end-diastolic left ventricular pressure > 24 mmHg was 40.5%. Patients with a left ventricular ejection fraction of 10-20% were not significantly more at risk (P > 0.05) than those with a left ventricular ejection fraction of 21-30%.

Adult↗
PubMed1992

Coordination of the legs of a slow-walking cat.

On the basis of behavioural studies the influences that coordinate the movement of the legs of a slowly walking cat have been investigated. The recording method applied here allows for the measurement of forward and backward movement of the legs which are called swing and stance movements, respectively. Influences between contralateral legs, i.e. both front legs or both hind legs, are stronger than those occurring between ipsilateral legs, i.e. front and hind leg of the same side. Influences which coordinate the front legs seem to be of the same kind as those for the hind legs. These influences are symmetrical, which means that the same type of influence acts from right to left leg and in the reverse direction. Two types of influences are described for contralateral legs: 1. When the influencing leg performs a swing movement, the influenced leg is prevented from starting a swing movement. 2. When the influencing leg performs a stance movement, the probability that the influenced leg starts a swing movement increases as the influencing leg moves backwards during its stance movement. In contrast to contralateral coupling, the ipsilateral influences are symmetric, i.e. a different influence acts from front to hind leg than does in the reverse direction. The front leg is influenced to start a swing when both legs have approached each other to a given value. The hind leg is influenced to start a stance movement after the front leg has begun its swing.

Animals↗
PubMed1992

Early diastolic left ventricular function as a marker of acute cardiac rejection: a prospective serial echocardiographic study.

Changes in left ventricular early diastolic time intervals are sensitive indicators of incipient left ventricular dysfunction. We tested the hypothesis that acute rejection in cardiac transplant recipients is associated with alteration of early diastolic myocardial function, as expressed by the time interval Te, a parameter derived from digitized M-mode echocardiograms. Te is defined as the time interval between maximal posterior wall contraction and the point of peak posterior wall endocardium retraction velocity, as determined by the nadir of the computed first derivative curve. In transplant patients without rejection (group A, n = 48), Te was prolonged compared to healthy individuals (group C, n = 35) (79.0 +/- 12.5 ms vs 64.0 +/- 7.9 ms; p < 0.0001). During acute rejection (group B, n = 18) transplant patients had significantly longer mean Te values compared to transplant patients without rejection (group A) (97.8 +/- 17.9 ms vs 79.0 +/- 12.5 ms; p < 0.0001). Longitudinal studies in individual patients (group D, n = 18) demonstrated that rejection is associated with prolongation of Te (94.5 +/- 16.0 ms during rejection vs 79.0 +/- 10.3 ms before rejection; p < 0.0002) and that Te returns to individual baseline values in response to treatment (79.2 +/- 9.4 ms after therapy vs 79.0 +/- 10.3 ms before rejection; NS). In a prospective study, Te changes in transplant patients (group E, n = 96) were correlated with myocardial biopsy results. Sixty-one biopsies showed acute rejection, and 115 biopsies were negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1992

Recovery of end-organ failure during mechanical circulatory support.

To evaluate organ recovery during mechanical assistance, respiratory, hepatic and renal function parameters of 40 patients who underwent bridge-to-transplant procedures were reviewed retrospectively. Mechanical circulatory support was indicated if the hemodynamic and clinical status deteriorated despite pharmacotherapy with catecholamines, vasodilators, and intravenous use of the phosphodiesterase inhibitor enoximone. Sequelae of cardiogenic shock such as renal, hepatic and respiratory insufficiency were not considered a contraindication for mechanical support. The analysis of preimplant data such as serum creatinine, liver enzymes and pulmonary gas exchange did not identify any predictive indicator of irreversible organ damage. Functional recovery of preexisting respiratory, hepatic and renal dysfunction was found in 91%, 90%, and 85%, respectively. Subsequent transplantation, however, was affected by the number of failing organs prior to mechanical support. Of 17 patients with isolated organ failure prior to assist, 14 (82%) were transplanted. By contrast, 9 (75%) of 12 with combined failure of two organs, and only 6 (54%) of 11 patients with clinical patterns of three failing organ systems received transplants. In all patients who underwent successful transplantation, transplantability was associated with rapid organ recovery within 10 to 15 days after initiating mechanical assistance.

Adolescent↗
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↗
PubMed1992

[Coronary revascularization in end-stage coronary heart disease in relation to assessment of myocardial vitality].

From 4/1986-12/1990, 177 pts. with endstage coronary artery disease (CAD) and left ventricular ejection fraction 10-30% received coronary artery bypass grafting (CABG). Preoperatively myocardial infarction rate was 1.5 (mean). Presupposition for CABGs was myocardial ischaemia at present demonstrated in myocardial viability test. 66.1% of the pts. had signs of ischaemia at e.c.g. after work. Additionally 97.6% of the pts. had myocardial ischaemia defined as redistribution in myocardial scintigraphy. Angina pectoris was present in 93.8% of the pts. preoperatively. 1-5 (mean 2.9) CABG per pt. were performed. 35 pts. received an internal mammaria bypass to the left coronary artery also. Operative mortality was 11.3% (1986-1990) and in 1990 alone 7.3%. Actuarial survival rate was calculated after one year to 87.4% after two years to 86.1% and after three years to 84.8%. Postoperatively all pts. were free from angina pectoris. 5 months after the operation e.c.g. after work was performed. The physical stress bearing area was increased to 82.7 Watt (mean) compared to 51.7 Watt (mean) preoperatively (p less than 0.001 s.). In conclusion pts. with endstage CAD and left ventricular ejection fraction 10-30% appeared to be good candidates for CABG with good prognosis and significant symptomatic improvement when signs of myocardial ischaemia are present preoperatively.

Aged↗
PubMed1991

[Therapy of terminal heart failure using heart transplantation].

Heart transplantation (HTx) has now become an accepted treatment modality for end-stage heart disease. The limited supply of suitable donor organs imposes constraints upon the decision of who should be selected for transplantation. Usually patients are candidates for HTx, who remain NYHA functional class III or IV despite maximal medical therapy. Further criteria are low left ventricular ejection fraction (less than 20%) with heart rhythm disturbances class IIIA-V (LOWN), which are associated with poor prognosis. Additionally, the suffering of the patient and also the course of heart failure are essential for judging the urgency of HTx. Contraindications are absolute in patients with untreated infections, fixed pulmonary vascular resistance (PVR) above 8 WOOD-degrees, severe irreversible kidney and liver disease, active ventricular or duodenal ulcers and acute, psychiatric illness. HTx is relatively contraindicated in patients with diabetes mellitus, age over 60 years, PVR above 6 WOOD-degrees and an unstable psychosocial situation. To prevent rejection of the transplant heart, live-long immunosuppressive therapy is needed. Most immunosuppressive regimes consist of Cyclosporine A and Azathioprine (double drug therapy) or in combination (tripple drug therapy) with Prednisolone. For monitoring of this therapy, control of hole blood cyclosporine A level and white blood count is needed. Rejection episodes can be suspected if there is a greater than 20 mmHg decrease of systolic blood pressure, elevated body temperature, malaise, tachycardia or heart rhythm disturbance. The diagnosis of cardiac rejection can be established by endomyocardial biopsy. Measurement of the voltage of either the surface or intramyocardial ECG, echocardiography with special consideration to early left ventricular filling time as well as immunological methods are additionally used tools. Graft sclerosis as the main risk factor of the late transplant period remains an unsolved problem.

Adaptation, Psychological↗
PubMed1991

[Risk of adrenal cortex insufficiency following heart transplantation].

In 20 patients we studied the function of the corticotropic pituitary and adrenal gland 13 to 45 month (m = 27.1) after heart transplantation (HTx). For prophylactic immunosuppression all patients were treated with triple drug therapy, including Cyclosporine A, Azathioprine and Prednisolone. After performing the CRH-test we could demonstrate, that in all patients, treated with Prednisolone (0.09-0.15 mg/kg/day) for more than 1 year, adrenal insufficiency was evident. Patients must be controlled carefully, if therapy with steroids is stopped thereafter, not only because of increased risk of rejection but also because metabolic disturbance caused by adrenal insufficiency may occur. In case of elevated demand of steroids (i.e. infections or surgery), adequate substitution with glucocorticosteroids is needed.

Adrenal Cortex Function Tests↗
PubMed1991

Mechanical left ventricular support as a bridge to cardiac transplantation in childhood.

The mechanical extrathoracic "Berlin Heart" cardiac assist device was used for left ventricular support in an 8-year-old child of 27 kg body weight. Terminal left ventricular failure and life-threatening ventricular tachyarrhythmias in this child were sequelae of coarctation of the aorta, aortic stenosis and resultant severe left ventricular dilatation, hypokinesia and fibrosis. With the assist device, cardiogenic shock could be reversed. The child was extubated and mobilized during an 8-day waiting period for orthotopic heart transplantation. This case illustrates that the use of ventricular assist devices can be successfully extended to children and may be advantageous compared to other techniques of mechanical circulatory support, such as balloon pumping or extracorporeal membrane oxygenation.

Age Factors↗
PubMed1991

Patient selection for mechanical circulatory support as a bridge to cardiac transplantation.

Between 7/87 and 9/90 thirty-four patients underwent total artificial heart (Berlin Heart) (n = 2) or biventricular assist device (Berlin Heart) (n = 32) implantation as a bridge to cardiac transplantation. The time of mechanical support ranged from 2 to 60 days, for a mean of 19.2 days. Twenty-three patients received heart transplants, with 74% 30-day survival and 52% long-term survival. Implantation of a mechanical support system became indicated in those patients whose hemodynamic and clinical condition deteriorated despite treatment with enoximone in addition to maximal sympathomimetic medication. The strategy to administer enoximone routinely was the result of a prospective study on 24 pretransplant patients in whom enoximone therapy reduced the need for mechanical assistance by 62%. At the time of device implantation shock-related organ impairment such as cerebral, renal, hepatic, and respiratory dysfunction was present in 62% of patients. In addition, 7 patients had pneumonia. During mechanical support complete recovery of end-organ failure and resolution of pneumonia was observed in the majority of patients. The results indicate that end-organ dysfunction per se should not be considered a contraindication to mechanical circulatory support as a bridge to cardiac transplantation. However, further clinical investigations are needed to identify predictive indicators of irreversible organ damage.

Adult↗