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Biomedical subjects

H Weidemann

Publications and source records attributed to H Weidemann.

At least 55 records · Page 3Linked to original sources
PubMed1990

Experience with vascular grafts in total artificial heart replacement.

In total artificial heart replacement the pumps are attached to the vascular system with the help of connectors. These consist of a woven Dacron vessel graft to which a short silastic segment is vulcanized. In 36 calves surviving total artificial heart replacement between one and seven months (average 85 days) the morphological alterations due to interfacial reactions were studied: thrombus formation and neointimal fibrous hyperplasia at the anastomoses. In 15 calves (41.7%) thrombus growth within the outflow tract led to anastomotic stenosis: pulmonary artery 14 (93.3%), aorta-anastomosis 1 (2.8%), both vessels 1 (2.8%), in combination with pannus growth in atrial location 13 (86.7%). In 73.3% the pannus consisted of infected organized thrombus imitating the course of septic vegetative endocarditis. Two calves were reoperated in order to remove the vegetative thrombi, one successfully. In five animals pulmonary stenosis was the main cause of death. The presence and location of excessive tissue growth and thrombus formation within the outflow tract are also inherent to the fluid mechanical design of the valve. Neointimal fibrous hyperplasia at the anastomoses of the grafts seems to be a reparative process started up by platelet-induced subendothelial cell proliferation in response to intimal injuries.

Anastomosis, Surgical↗
PubMed1989

[Heart surgery in terminal kidney failure and dialysis dependent patients. Intraoperative hemofiltration for the prevention of hyperhydration].

12 hemodialysis-dependent patients underwent heart surgery involving cardiopulmonary bypass. Their example outlines the special pre-, intra- and postoperative management in these patients. Intraoperative hemofiltration seems appropriate to prevent fluid overload caused by cardiopulmonary bypass. 3 patients died within the first two weeks after operation. 9 patients are well after 4 to 30 months. The results are compared to the reports found in the literature.

Adult↗
PubMed1988

[Coronary risk factors and their relation to psychosocial factors in females with myocardial infarct].

UNLABELLED: 237 female patients aged 31-76 years with documented first myocardial infarction were examined on an average of 3 month after the acute event. Risk factors of coronary heart disease, sociobiological and psychosocial variables were assessed via standardized questionnaire. Risk factors were correlated with social characteristics, somatic and psychosocial variables. RESULTS: 1. Hyperlipoproteinemia is correlated with risk factors of nutrition (hypercholesterinemia resp. hypertriglyceridemia, obesity). 2. The analysis of smoking habits reveals a positive correlation with social characteristics (e.g. professional status) and also with the amount of experienced stress. 3. The use of oral contraceptives corresponded with young age of fertile women and also with professional status. Furthermore a correlation with a positive working attitude and smoking behavior was found.

Adult↗
PubMed1988

[Cardiac exercise tolerance of infarct patients in exercise therapy].

UNLABELLED: 92 female patients with myocardial infarction were divided into three exercise groups of 25 W, 50 W and 75 W according to their symptom-limited working capacity and examined during bicycle ergometer training. Exercise tolerance, training heart rate and arterial lactic acid were analyzed. RESULTS: 1. Increase in maximal working capacity corresponds to a decrease in limiting cardiac symptoms, or an increase of limiting symptoms, e.g., in tired leg muscles. 2. Intensity of training (as a percentage of maximal symptom-limited work capacity) is 55 +/- 21%, 73 +/- 15%, and 90 +/- 8% for groups of 25, 50 and 75 W (p less than 0.05) respectively. 3. Training heart rate and lactic acid increase significantly proportional to the increase of work capacity. 4. In all three exercise groups, training heart rate corresponds to about 84% maximal heart rate measured at maximal working capacity. 5. Mean maximal lactic acid level is at 3.18 +/- 0.97 mmol/l for the whole exercise group on 75 W. Within this group, only a small subgroup of seven women, who were limited in maximal working capacity by tired leg muscles, reached the so-called anaerobic threshold of 4 mmol/l lactic acid. 6. Female patients greater than or equal to 60 years have partially significant higher mean lactic acid levels for the same exercise load as women less than or equal to 59 years. CONCLUSION: Gender specific differences in performance in women and the cardiac situation in female patients were considered on the basis of symptom-limited performance and body-weight-related physical training, regulated by individual training heart rate.

Angina Pectoris↗
PubMed1987

Comparative study of long-term effects of Molsidomin 8 mg (slow release form) and ISDN 40 mg (slow release form) on angina pectoris and ischaemic ST-segment depression during maximal bicycle-ergometry in patients with coronary insufficiency.

The results of a randomized double-blind study with two comparable treatment groups are reported. In the course of treatment the frequency of angina pectoris during exercise as measured by a 4-point rating scale of symptom intensity decreased significantly for both groups. In comparison to the base line data the mean total workload increased significantly in both treatment groups (Molsidomin from 379 to 526 watt min; ISDN from 382 to 524 watt min-1). The product of systolic blood pressure and heart rate (BP X HR) under maximal workload increased significantly in both groups (Molsidomin from 17.5 to 20.9 mmHg min-1 1000(-1); ISDN from 17.7 to 20.2 mmHg min-1 1000(-1). The decrease in the ischaemic ST-segment depression on the level of maximal workload of the base line test was significant for both groups for all measures (Molsidomin from 0.27 to 0.08 mV; ISDN from 0.28 to 0.07 mV). The decrease of the ST-segment depression on the individual maximal workload level was significant for all measures in the Molsidomin group, but only on the first day of treatment in the ISDN group.

Angina Pectoris↗
PubMed1985

Chromium bond detection in isolated erythrocytes: a new principle of biological monitoring of exposure to hexavalent chromium.

Internal stress to chromium is only relevant in occupational medicine if it is due to the handling of hexavalent chromium. Cr(VI) ions, after uptake by inhalation or percutaneously are carried in the blood plasma and penetrate--depending on the concentration--into the erythrocytes. Due to the intracellular reduction to Cr(III) and the concurrent intracellular protein binding, the erythrocytes represent an easily accessible target organ for quantitative chromium determination after occupational exposure to Cr(VI) compounds. The results of an earlier experimental study indicate that human plasma too is capable of spontaneous reduction of Cr(VI) ions of up to 2 ppm to Cr(III). This plasma reduction capacity (PRC) can be increased and accelerated considerably by adding ascorbic acid (AA). These findings were supported in this investigation by proving a decreased binding of Cr(VI) inside the erythrocytes under the effect of AA. This leads to the assumption that only those Cr(VI) concentrations can penetrate the membrane of the erythrocytes and enter the cell which either come into contact with the membrane during the reduction process or exceed this limit concentration of 2 ppm. Only in these two instances can corresponding chromium findings be analyzed in isolated and washed erythrocytes. These results are compared with those obtained by conventional methods, such as Cr determination in the blood and/or urine. Our findings indicate that a single determination of chromium concentration in the erythrocytes will permit the monitoring of critical cases of Cr(VI) exposure. This is a new type of biological monitoring in the sense of a condensed longitudinal study, in order to find out whether threshold concentrations have been respected over a given period.

Air Pollutants, Occupational↗
PubMed1985

[Significance of fixed anaerobic threshold, training lactate and training heart rate for bicycle ergometer training with myocardial infarct patients].

UNLABELLED: 302 male myocardial infarction patients were divided into 4 groups according to their symptom-limited physical working capacity and examined during bicycle ergometer training. Lactic acid and heart rate during training were measured. RESULTS: Arterial lactic acid and training heart rate decreased proportionally with the reduction of the maximal symptom-limited working capacity. Arterial lactic acid levels in 4 training groups of 100, 75, 50 and 25 watts were 2.23 (2.56) mmol/l, 1.87 (2.32) mmol/l, 1.58 (1.73) mmol/l and 1.20 (1.11) mmol/l, respectively, p less than 0.001 (in bracket = with beta blocker). Decrease in arterial lactic acid levels according to the reduction of working capacity corresponded to a decrease of training heart rate. In patients with beta blocker therapy results were less pronounced. Intensity of training corresponded to about 80% of VO2 measured as maximal symptom-limited physical working capacity. Training heart rate corresponded to about 85% of maximal heart rate as measured at symptom-limited physical working capacity. The so-called fixed anaerobic threshold of 4 mmol/l lactic acid was not reached by patients with myocardial infarction up to a training intensity of 100 watts (approximately 1.3 watts/kg). From this study it can be concluded that fixed anaerobic threshold and lactic acid are of secondary importance in determining the intensity of endurance training in patients with myocardial infarction.

Adrenergic beta-Antagonists↗
PubMed1983

[Cardiac work capacity and training load in women with coronary heart disease].

Among 1178 patients the data of 11 women with early rehabilitation after cardiac infarction, 30 women with late rehabilitation after infarction and 40 women with coronary heart disease without cardiac infarction were assembled. The women were exercised according to their ergometric and microcatheter workload tolerance. The symptom-limited maximal Watt-load increased significantly in all three groups in patients with "normal cardiac function" and "abnormal ventricular function" from admission to discharge investigation. There was no increase of workload tolerance in women with exercise-induced cardiac insufficiency. The average ergometric training load was increased significantly in patients with "normal cardiac function" and "abnormal ventricular function" in all three groups during four weeks of treatment. There was no increase of training workload in patients with exercise-induced cardiac insufficiency. Symptom-limited maximal Watt-pulse values and average absolute training workload values of the three groups differed by a quarter to a third from the values of comparable male groups. The relative bodyweight-related Watt-exercise values showed no differences between females and males.

Coronary Disease↗
PubMed1983

Hemodynamic measurements and exercise testing to assess the development of tolerance against slow-release isosorbide dinitrate.

Hemodynamic measurements were carried out during exercise testing with floating catheterization in 12 male patients with multiple-vessel disease and stable angina pectoris after placebo, after acute treatment with 60 mg ISDN, and after 4 weeks treatment with 4 X 60 mg ISDN. The acute effects of ISDN at the maximal comparable workload were a 32% decrease in PAd, a 41% decrease in ST-segment depression, and a 35% increase in maximal workload. After 4 weeks therapy we found an attenuation of the efficacy of ISDN, with only a 12% decrease in PAd, a 33% decrease in ST-segment depression, and an 18% increase in maximal workload.

Blood Pressure↗
PubMed1982

[The axillofemoral bypass as an aortoiliac principle of reconstruction in high risk patients. Long term results from 1970-1979 (author's transl)].

A total of 95 consecutive high-risk patients (average age of 68.28 years) underwent 114 axillofemoral bypass operations for revascularization of 116 lower extremities (1970-1979); 84.48% were in stage III and IV. Four bypass variations were used: unilateral bypass (70.8%), crossing bypass (4.4%), bilateral procedure (10.6%) and axillobifemoral bypass (14.2%). In elective operations, the operative mortality was 6.3%; in emergency operations one of 3 patients died. The unilateral bypass including the 5 patients on whom the crossing bypass was used showed a cumulative 5-year patency rate of 51.60%; the bifemoral bypass had a rate of 77.14% and in cases of bilateral bypass no graft was patent after 5 years. Graft thrombosis was the most common complication (47.37%); successful revision was possible in only 53.75%. In case of bifemoral procedure, graft thrombosis occurred in only 29.41%. Therefore, the authors recommend that stricter indications be employed for surgery: an axillofemoral bypass operation should only be performed in cases in stage III and IV for limb salvage and only in a "real" high-risk patient. In addition, the axillobifemoral variation should also be preferred in all cases of bilateral occlusive disease with unilateral symptomatology.

Age Factors↗
PubMed1982

The role of psychosocial risks in patients with early myocardial infarction.

Results of a retrospective case-control study on 380 male patients with clinically documented first myocardial infarction (age 30-55) as well as findings of a follow-up over 18 months of 70% of this sample are presented. First, the presence of somatic risk factors and in a subsample of 53 patients, degree of atherosclerosis as demonstrated by coronary angiography are documented. Second, the role of possible additional risks due to higher nervous activity, and especially to neurohormonal imbalance, is explored by analyzing psychosocial risk constellations of the MI group vs. healthy controls. It is shown that significantly greater parts of MI subjects can be classified as simultaneously exposed to several chronic and acute social risks and that social stressors are related to the recurrence of cardiac symptoms in a follow-up after rehabilitation. Findings are discussed with reference to evidence from prospective studies, and the question of validity of reported data is addressed to by controlling for possible methodological bias such as the role of denial and neuroticism in patients under study and influences caused by interviewers. It can be demonstrated that findings basically remained stable after controlling for these biases. Finally, additional evidence for the validity of subjective stress rating is presented.

Adult↗