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Biomedical subjects

W Burger

Publications and source records attributed to W Burger.

At least 55 records · Page 3Linked to original sources
PubMed1993

Serial evaluation of left ventricular function by radionuclide ventriculography at rest and during exercise after orthotopic heart transplantation.

Discrepant results have previously been reported concerning long-term left ventricular function in the human transplanted heart as assessed by radionuclide ventriculography. In this study, radionuclide ventriculograms were obtained at rest and during exercise in 19 patients < 6 months, 7-12 months, 13-24 months and > 24 months after transplantation. Ejection fraction decreased significantly from < 6 months to 13-24 months after transplantation (rest: 69.1% +/- 9.7% to 56.7% +/- 8.3%, P < 0.05; exercise: 70.4% +/- 11.3% to 59% +/- 8%, P < 0.05). Heart rate increased significantly during exercise after > 2 years (90.2 +/- 10.5 beats/min to 103.5 +/- 15 beats/min, P < 0.05) but not within 6 months after transplantation (98.5 +/- 12.8 beats/min to 99.07 +/- 15.8 beats/min). Left ventricular end-diastolic volume remained unchanged. Peak filling rate at rest decreased significantly from 4.2 +/- 0.96 edv/s < 6 months after transplantation to 3.3 +/- 0.66 edv/s (P < 0.05) 13-24 months and 3.3 +/- 0.64 edv/s (P < 0.05) > 24 months after cardiac transplantation. Exercise peak filing rate did not change significantly. It is concluded that radionuclide ventriculography demonstrates a decrease in systolic left ventricular function in the long-term course after cardiac transplantation. A significant increase in exercise peak heart rate may be due to autonomic reinnervation. Differences in the literature concerning left ventricular function may be due to different observation intervals following cardiac transplantation.

Erythrocytes↗
PubMed1993

The value of radiotherapy or chemotherapy after intubation for advanced esophageal carcinoma--a prospective randomized trial.

After intubation for advanced, inoperable squamous carcinoma of the oesophagus, a prospectively controlled randomized trial was done to investigate the effect of radiotherapy (41 patients) or mono-chemotherapy (40 patients) or no further treatment (46 patients). Treatment had no significant effect on either palliation or survival (p < or = 0.7) and did not alter the natural history of the disease.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Effects of exercise or temporary coronary occlusion during angioplasty on right ventricular function with consideration of left-anterior-descending- and right-coronary-artery-related myocardial ischemia.

Whether exercise causes right ventricular ischemia severe enough to depress right ventricular function is still controversial. Therefore, right ventricular function was evaluated in 44 patients with isolated coronary artery disease of either the proximal left anterior descending or right coronary artery during exercise (n = 22) or balloon occlusion during percutaneous transluminal coronary angioplasty (PTCA) (n = 22). Central hemodynamics and right ventricular volumes were determined using a new thermodilution Swan-Ganz catheter. Exercise increased right ventricular end-diastolic volume index [from 89 (66-127) to 101 (70-130) ml m-2, p = 0.00005; median (range)] and stroke volume index [from 44 (27-68) to 53 (36-75) ml m-2, p = 0.0005]. During PTCA, right ventricular end-diastolic volume index remained unchanged, while stroke volume index decreased from 49 (38-60) to 40 (26-49) ml m-2 (p = 0.00005). The decrease in right ventricular ejection fraction during exercise from 56 (41-64) to 52% (39-64) reached only borderline significance (p = 0.06) and was significantly (p = 0.02) smaller than during angioplasty [from 53 (44-62) to 41% (25-66; p = 0.0008)]. Right ventricular ejection fraction did not differ between left anterior descending or right coronary artery obstruction and did not depend on right ventricular afterload. In comparison to exercise angioplasty caused a decreased systolic pressure-volume ratio and a leftward shift of the diastolic pressure-volume curve. In conclusion, exercise has only little effect on right ventricular ejection fraction, whereas inadequate oxygen supply during balloon angioplasty induces severe depression of right ventricular function.

Adult↗
PubMed1993

[Right ventricular function in patients with rheumatic mitral valve stenosis. Effect of balloon mitral valvuloplasty].

UNLABELLED: Postrheumatic mitral stenosis might cause impairment of right ventricular (RV) function due to both an increase in RV afterload and rheumatic myocardial disease. Therefore, we investigated in 19 patients with postrheumatic mitral stenosis and sinus rhythm right ventricular volumes and hemodynamics by a computerized thermodilution catheter during rest and supine bicycle exercise. In 14 patients the investigation was repeated within 2 days after balloon mitral valvuloplasty. Resting RV ejection fraction was decreased (43 (15-53)%, median (range)) and correlated significantly with RV end-systolic volume index (r = -0.90), stroke volume index (r = 0.77), RV end-diastolic volume index (r = -0.76), heart rate (r = -0.69), pulmonary artery resistance (r = -0.69), and mean pulmonary artery pressure (r = -0.68). RV end-diastolic volume index was 107 (81-200) ml/m2. Exercise induced a decrease of RV ejection fraction to 36 (13-48)% at 50 Watt (p < 0.001), while it increased RV end-diastolic volume index to 131 (78-231) ml/m2 (p < 0.001). Balloon mitral valvuloplasty improved RV ejection fraction at rest from 41 (15-47)% to 48 (39-55)% (p < 0.005) and from 30 (13-46)% to 43 (27-56)% during exercise (p < 0.005). The increase of RV ejection fraction after valvuloplasty was caused by an increase in stroke volume, but not by a reduction in RV end-diastolic volume. CONCLUSION: Depending on the increased RV afterload, RV function is markedly depressed in mitral stenosis. An immediate and almost complete improvement of RV function occurs with the reduction of RV afterload after balloon mitral valvuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Main branch stenosis after bypass operation. Indications for elective PTCA].

The unprotected left main stenosis still represents one of the contraindications of PTCA; recently developed concepts using percutaneous bypass techniques have not changed this fact so far. However, following bypass grafting the procedure can be done with low risk and may improve prognosis in case of later bypass occlusion. This study should clarify whether a higher rate of bypass occlusion is caused by postsurgical left main PTCA. From October 1981 to January 1991 a left main stenosis was dilated in 41 patients, 2 weeks to 12 years (mean 3.5 years) after bypass grafting. To date, 17/65 venous bypass grafts were already occluded, and 72.4% of the patients suffered from typical angina. In 34/41 patients (82.9%) PTCA was successful, severe complications (death, emergency surgery or myocardial infarction) did not occur and clinical improvement was achieved in 80% of symptomatic patients. Four months later, 26/34 patients (76.5%) had angiographic follow-up. Fifteen restenoses were found and a second PTCA was performed in 9/15. None of the venous bypass grafts, open at the time of the first PTCA, was occluded at follow-up. In one case PTCA of the left main stenosis turned out to be life-saving 7 years later because an occlusion of RCA- and LCX-bypasses occurred and the LAD graft showed a subtotal thrombosis. It is concluded that PTCA of left main stenosis after bypass grafting is a safe procedure and does not lead to a higher rate of venous bypass occlusions. A prognostic indication seems to be justified.

Adult↗
PubMed1992

A word of caution: reopening chronic coronary occlusions.

Reopening of chronically occluded coronary arteries by angioplasty, initially considered a low risk procedure, may carry similar risks at PTCA of coronary stenoses. We report 3 cases with ventricular fibrillation or sudden death 2-4 days after reopening of 1- to 5-month-old coronary occlusions.

Aged↗
PubMed1992

Collagen application for sealing of arterial puncture sites in comparison to pressure dressing: a randomized trial.

One hundred patients undergoing routine diagnostic or interventional catheterization were randomly assigned to receive either percutaneously applied collagen (group A; n = 50) or conventional pressure dressing (group B; n = 50) for sealing of the femoral artery. Clinical variables were comparable in both groups. The heparin dose was 100 IU/kg in 30 patients and 200 IU/kg in 20 patients of either group. The average compression time was 4.3 min in group A and 42.3 min in group B (p < .001). Bleeding was not observed in group A but was observed in 6/50 patients in group B. The time to ambulation was 6.4 hr (range, 4-12 hr) in group A and 21.6 hr (range, 10-48 hr) in group B (p < .001). Hematomas with a diameter of > 6 cm developed in 4/50 patients in group A and in 11/50 patients in group B (p < .05). Blood-transfusions or surgical interventions were not required and there was no loss of ankle pulses in either group. In conclusion, percutaneously applied collagen reduced compression time and duration of bedrest after diagnostic catheterization and PTCA. Despite earlier ambulation, the incidence of bleeding was lower with collagen than with conventional pressure dressing.

Aged↗
PubMed1992

Right ventricular volumes and hemodynamics after successful orthotopic heart transplantation. A comparison to coronary artery disease using thermodilution.

Only few data exist concerning right ventricular function in the chronic stage after cardiac transplantation. Therefore, we investigated hemodynamic and right ventricular volumetric data by a computerized thermodilution Swan-Ganz catheter in 17 patients (median age: 53, range: 18-63 yr) at a median of 24 (4 to 44) months after cardiac transplantation during rest and supine bicycle exercise. Myocardial biopsy showed grade one or less according to the classifications of Billingham. Sixteen patients with coronary artery disease, but without prior myocardial infarction, served for comparison. While angiographic left ventricular ejection fraction was nearly identical in transplant recipients [77 (60-92)%, median (range)] and in patients with coronary artery disease [78 (64-94)%], right ventricular ejection fraction was lower (p < 0.001) in patients after cardiac transplantation [37 (16-58)%] as compared to patients with coronary artery disease [56 (46-62)%]. In transplant recipients right atrial pressure was significantly higher both at rest [10 (2-18) mmHg] and exercise [18 (8-30) mmHg] than in patients with coronary artery disease [5 (1-11) and 8 (3-18) mmHg]. Pulmonary capillary wedge pressure behaved similar in both groups. To further evaluate reasons for right ventricular impairment, a correlation analysis was performed. This showed a negative correlation between right ventricular ejection fraction and the time interval after transplantation (p < 0.0002). However, there was no correlation between right ventricular ejection fraction and acute rejection or a rejection score. In conclusion, right ventricular function may be severely altered in transplant recipients, in contrast to an only slight impairment of left ventricular function.

Adolescent↗
PubMed1992

A phase II study of 5-fluorouracil and leucovorin in advanced carcinoma of the esophagus.

Thirty-five patients with advanced epidermoid carcinoma of the esophagus were treated with 5-fluorouracil (5-FU) 425 mg/m2 and leucovorin 20 mg/m2, day 1-5 every 28 days. Six patients had a partial response (95% confidence limit, 7-35%) with a median response duration of 32 weeks. The median survival time of the patients on study was 14 weeks. The toxicity was acceptable, with only two patients experiencing severe hematologic toxicity and one patient experiencing severe nausea and vomiting. The addition of leucovorin at this dose level in this population of patients with advanced disease does not appear to enhance the activity of 5-FU for patients with squamous cell cancer of the esophagus. Since only a small percentage of patients experienced significant toxicity, a higher response rate could be achieved in patients treated with the maximally tolerated dose.

Adult↗
PubMed1992

Comparison of negative inotropic and vasodilator effects of isradipine and nifedipine after complete autonomic blockade in ischemic heart disease.

The cardiodepressant and vasodilator effects of an intravenous (i.v.) infusion of 0.5 mg isradipine or 2 mg nifedipine were interindividually (10 vs. 10 patients) compared in a double-blind study in patients with stable coronary heart disease. To minimize vasodilation-induced autonomic reflex mechanisms, which may counterbalance negative inotropic effects after acute administration of calcium antagonists, i.v. autonomic blockade was produced by 0.2 mg/kg propranolol and 0.04 mg/kg atropine. Systemic hemodynamics were measured before and 15 min after the end of the 15-min calcium antagonist infusion. After administration of both drugs, heart rate (HR) decreased similarly during the observation period (isradipine from 93 +/- 10 to 88 +/- 9 beats/min and nifedipine from 84 +/- 9 to 79 +/- 6 beats/min, both p less than or equal to 0.01). The reduction in total peripheral resistance (TPR) was significantly (p less than or equal to 0.01) greater after isradipine (from 1,376 +/- 285 to 1,002 +/- 224 dynes s cm-5) than after nifedipine (1,258 +/- 262 to 1,112 +/- 225 dynes s cm-5). Between the two drugs, the difference in the reduction of afterload independent dP/dt40, determined by tip-manometry, reached borderline significance (p = 0.08) (isradipine from 1,197 +/- 258 to 1,157 +/- 225 mm Hg/s, NS and nifedipine 1,228 +/- 226 to 1,109 +/- 227 mm Hg/s, p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nerve Block↗
PubMed1992

Acute and mid-term experiences with the Wiktor stent in acute complications and restenosis after coronary angioplasty.

We report about the 6-month follow-up of 28 consecutive patients treated with a new tantalum stent (Wiktor¿ stent, Medtronic, Inc.). Indication for stenting was the prevention of restenosis in eight patients (restenosis group), and threatening or acute closure after PTCA in 20 patients (acute closure group). Twenty-eight of 30 stents were successfully positioned in 27 of 28 patients (96%), whereas implantation failed twice in one patient. Immediate stent occlusion developed in two patients in the acute closure group (7.4%) Subacute stent occlusion was observed in three patients (11%), one in the restenosis group, two in the acute closure group, between 3 and 5 days after implantation. Coronary bypass surgery had to be performed in four patients (15%): one patient after failed stent placement, two after acute, and one after subacute stent thrombosis. Major bleeding complications related to the anticoagulative drug regimen occurred in nine patients (33%). Three patients (11%) died for reasons most probably not related to stent implantation. A 6-month angiographic follow-up revealed restenosis in two of 19 patients (11%), one patient in each group. Sixteen of the 27 stented patients (59%) reached 6-month follow-up without death, acute or subacute stent thrombosis, or restenosis. It is concluded that the Wiktor stent can be placed with a high rate of success. It may also reduce the risk of restenosis. The stent also offers the possibility to circumvent emergency bypass surgery in case of PTCA related vessel occlusion. Acute and subacute stent occlusion still remains an unsolved topic.

Adult↗
PubMed1992

[Chronic coronary artery occlusion--age, morphology and chance of reopening. An attempt to define indications].

In chronic coronary occlusions the rate of successful reopening seems to be improved with the help of new techniques; the chance of success can be judged by the age of occlusion. Frequently this age cannot be fixed exactly. The purpose of the study was therefore to find out, whether the chance of reopening can be judged by morphology. 60 patients in whom the occlusions could not be passed with a conventional wire were treated with the ROTACS system. Cine angios were reviewed carefully, morphological details in at least two projections were evaluated in graphic representations and correlated with the acute success rate and the estimated age of occlusion. Morphological parameters associated with a higher rate of success (type A) were: 1) a clearcut proximal stump with 2) no sidebranches at the site of occlusion, 3) no bridging collaterals and 4) only a slight filling of the distal vessel. Parameters with a low success rate (type B) were: 1) no proximal stump, 2) sidebranches at the site of occlusion, 3) bridging collaterals and 4) a very good distal filling. 48/60 (80%) of occlusions could be classified in type A or type B. The success rate was 17/21 (81%) (type A) versus 5/27 (18.5%) (type B) (p < 0.0002). The estimated age of type B occlusions was significantly higher than in type A: median 8 versus median 4 months (p < 0.002). It is concluded that the rate of success in reopening chronic coronary occlusions can be judged in the majority of patients using morphological parameters.

Atherectomy, Coronary↗
PubMed1991

Acute and chronic effects of nitrendipine in patients with precapillary pulmonary hypertension due to pulmonary fibrosis.

Eleven patients with histologically confirmed fibrosis of the lung were investigated for the effects of the dihydropyridine calcium antagonist nitrendipine on pulmonary hemodynamics. After 5 mg of acute sublingual nitrendipine, mean pulmonary artery pressure was significantly lowered (p less than or equal to 0.05) from 32 +/- 3 to 29 +/- 3 mmHg at rest, and significantly lowered (p less than or equal to 0.05) during exercise from 55 +/- 4 to 49 +/- 4 mmHg. Short-term oxygen application at rest significantly reduced this parameter to 28 +/- 3 mmHg (p less than or equal to 0.001). Nitrendipine lowered total pulmonary vascular resistance during both rest (from 412 +/- 50 to 351 +/- 49 dyn.s.cm-5; p less than or equal to 0.05), although it did not affect pulmonary arteriolar resistance. Also, oxygen treatment at rest influenced only total pulmonary vascular resistance (reduction from 412 +/- 50 to 373 +/- 48 dyn.s.cm-5; p less than or equal to 0.01), but not pulmonary arteriolar resistance. Pressure-flow curves, which were derived from cardiac output at rest and during exercise and from the corresponding gradient between mean pulmonary artery pressure and pulmonary capillary wedge pressure, remained unchanged by acute medication. Since a change in arterial oxygen partial pressure was not noticed after nitrendipine, arteriovenous shunting or a worsening of ventilation perfusion relationships can be excluded. Long-term (3 weeks) treatment (double-blind parallel design) with 10 mg of nitrendipine (4 patients) once daily showed no advantage in comparison to placebo (6 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗