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Biomedical subjects

G Kober

Publications and source records attributed to G Kober.

At least 73 records · Page 4Linked to original sources

Dose-related antiarrhythmic effects of nicainoprol in patients with chronic ventricular arrhythmias--a double-blind, placebo-controlled, cross-over multicentre trial. Nicainoprol Study Group.

One hundred and three patients with a history of ventricular arrhythmia were screened by baseline 24-h Holter monitoring for a minimal mean number of 30 premature ventricular beats (PVB) per hour. One hundred and one patients were subsequently enrolled in a double-blind, cross-over trial, including four 4-day periods with administration of placebo (PL) or nicainoprol (N.) in doses of 200, 400, 600 mg three times daily in randomized order. Antiarrhythmic efficacy could be evaluated in 61 patients who met all requirements of the protocol, including a complete sequence of valid Holter recordings (greater than 18 h each). Total PVBs were significantly reduced by the 400-mg dose (65%) and the 600-mg dose (71%) as compared to baseline. Two hundred mg N. and PL led to a non-significant reduction of PVBs by 41% and 24%, respectively. An individual response, assumed where there was simultaneous reduction of total PVBs greater than 75%, of ventricular pairs greater than 90% and elimination of ventricular runs, was found in 6 (10%), 10 (16%), 21 (34%), and 22 (36%) patients with PL, 200 mg N., 400 mg N. and 600 mg N., respectively. Four hundred and 600 mg N, significantly prolonged the PR interval (0.17 s and 0.18 s; median values) as compared with baseline (0.16 s), while the QRS duration was significantly increased only by the 600-mg dose (from 0.10 to 0.11 s). Heart rate, mean blood pressure, QT and JTc intervals were not significantly influenced by any dose of N.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Analysis of 100 emergency aortocoronary bypass operations after percutaneous transluminal coronary angioplasty: which patients are at risk for large infarctions?

Severe vascular complications are an inherent risk of percutaneous transluminal coronary angioplasty (PTCA). Data from 100 emergency aortocoronary bypass operations required after 2850 interventions (3.5%) were retrospectively analysed in order to identify factors that determine postoperative infarct size. Large infarctions were assumed if the patient died of cardiogenic shock (n = 12), if postoperative angiography demonstrated a decrease in left ventricular ejection fraction of more than 20% of if R-waves in the ECG decreased by more than 40% and a QRS-score increased by more than 5. According to these definitions, 29 patients experienced large infarctions, while 71 experienced no or only small infarctions. The following factors differentiated the two groups: age (58 vs 53 years, P = 0.008), pre-PTCA exercise work load (88 vs 118 Watts, P = 0.0001), exercise ischaemia score (2.7 vs 1.9, P = 0.045), degree of pre-PTCA stenosis (83 vs 86%, P = 0.03), coronary multivessel versus single vessel disease (60 vs 38%, P = 0.02), collaterals to the target vessel (10 vs 34%, P = 0.05), total vascular occlusion during PTCA (76 vs 56%, P = 0.035), and long duration of ischaemia after onset of the complication (253 vs 179 min, P = 0.012). Data from patients with large postoperative infarctions who survived ranged between those with no or small infarctions and those who died of cardiogenic shock. Higher age (P = 0.04), reduced exercise tolerance (P = 0.0004), absence of collaterals (P = 0.04), and duration of ischaemia until reperfusion (P = 0.001) were independent predictors of large postoperative myocardial infarctions.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗

[Comparison of ischemic pain threshold and reactive hyperemia in autonomic diabetic neuropathy and silent myocardial ischemia].

31 patients with coronary artery disease (11 patients with diabetes mellitus and autonomic neuropathy. 10 patients with diabetes without neuropathy, and 10 patients with asymptomatic myocardial ischemia) participated in a study designed to investigate whether there is a difference in forearm skeletal muscle ischemia and pain threshold. The degree of ischemia was determined by plethysmographically measured reactive hyperemia. There was no difference in maximum reactive hyperemia after passive forearm ischemia of 5-min duration in the three groups. After symptom-limited ischemic work, there was significantly more reactive hyperemia in patients with silent myocardial ischemia as compared to diabetic patients. Exercise time was longer in patients with silent myocardial ischemia (153 +/- 51 s) than in patients with diabetic neuropathy (139 +/- 45 s) and diabetics without neuropathy (120 +/- 45 s). Pain as a cause of termination of symptom-limited ischemic forearm exercise occurred less frequently in patients with diabetic neuropathy (2/11) and patients with silent myocardial ischemia (3/10) as compared to patients with diabetes without neuropathy. Patients with silent myocardial ischemia had a higher ischemic tolerance in the ischemic working forearm than did diabetic patients with and without neuropathy. In patients with neuropathy, however, ischemic pain occurred less frequently at the same ischemic work level compared to diabetics without neuropathy. Therefore, diabetic neuropathy appears to facilitate the occurrence of silent myocardial ischemia. The data presented here suggest that there is a qualitative difference in ischemic tolerance between patients with silent myocardial ischemia and patients with diabetic neuropathy.

Angina Pectoris↗

[Multiparametric analysis using radionuclide ventriculography in the assessment of left ventricular function following heart transplantation].

Left ventricular systolic and diastolic performance was evaluated by radionuclide angiography in 17 patients following cardiac transplantation and compared with normal persons. Both groups performed supine bicycle exercise during the investigation, the control group at 102 +/- 73 W and the transplanted patients at 61.2 +/- 15 W. The ejection fraction increased in the normal persons from 61 +/- 8 to 69 +/- 10% whereas in the transplanted patients it did not increase significantly. There were no relevant changes in systolic parameters during exercise in the transplant recipients. The changes in diastolic parameters were significantly smaller in transplant patients than in normals. After correction for heart rate-induced changes a significantly different time course of the systolic-diastolic sequence during the cardiac cycle became evident in the transplanted group at rest. During exercise the systolic-diastolic sequence during the cardiac cycle became similar in both groups. It is concluded that the reduced exercise capacity of patients in the late phase after cardiac transplantation is partially due to the absence of an EF increase and a limitation of diastolic reserve during exercise.

Adult↗

[Angioscopy of the coronary vessels].

Direct visual examination of the interior surfaces of intact human coronary arteries is now a reality, both from intraoperative and transluminal approaches. As an additional investigation to angiography it improves the knowledge about the corresponding morphology of angiographically visible changes. Since the first report about percutaneous and intraoperative coronary angioscopy by Spears et al. in 1982 important indications concerning the intraoperative approach were defined such as the control of coronary atherectomy, intraoperative balloon dilatation and laser angioplasty, the inspection of the grafts prior to implantation and the assessment of the quality of the distal anastomosis after graft insertion. The most important clinical result angioscopy has brought about is the postulation of a concept of the different clinical forms of coronary artery disease based on the morphological stages of atherosclerosis, which were defined by angioscopy and could be related to clinical symptoms. Scientific studies today are concerned with determinants for the patency rate of bypasses, the restenosis rate of PTCA, the acute and chronic effects of drugs, and the mechanism of all kinds of catheter-supported angioplasties. The next important application of coronary angioscopy will undoubtedly be the simultaneous visual control of coronary angioplasty procedures such as laser angioplasty and other new methods.

Coronary Artery Disease↗

T cell receptor gene rearrangements of T lymphocytes infiltrating the liver in chronic active hepatitis B and primary biliary cirrhosis (PBC): oligoclonality of PBC-derived T cell clones.

Immunological events are involved in the pathophysiology of chronic active hepatitis as indicated from the accumulation of T lymphocytes at the site of tissue damage. We generated T cell clones from liver biopsies of 3 patients with chronic active hepatitis B and 2 patients with primary biliary cirrhosis. These T cell clones (n = 84) were analyzed by means of T cell receptor (TcR) beta gene rearrangements to determine whether the infiltrate consists of a polyclonal or oligoclonal T cell population. The vast majority (62 of 64) of T cell clones from three different patients with chronic active hepatitis B showed no identical rearrangements of the TcR beta chain genes. In marked contrast, in both patients with primary biliary cirrhosis, T cell clones established were of limited diversity. Thus 5 out of 10 and 2 out of 10 T cell clones from one patient and 3 out of 9 and 2 out of 9 T cell clones from the second patient, respectively, showed identical TcR beta gene rearrangements. These data suggest that a clonal dominance is characteristic for local T cell responses in autoimmune liver disease such as primary biliary cirrhosis whereas in virus-induced chronic active hepatitis T cell activation occurs polyclonally.

Adult↗

Influence of carvedilol and propranolol on coronary blood flow.

A total of 17 patients with angiographically proven coronary artery disease and at least one stenosis blocking greater than or equal to 70% of the left anterior descending or circumflex artery were included in a double-blind, randomized study. They received either 5 mg carvedilol or 6 mg propranolol intravenously. Heart rate, aortic pressure, mean coronary sinus pressure and coronary flow (thermodilution) were measured and coronary resistance and the rate-pressure product were calculated before and 25 min after injection. Carvedilol significantly (P less than 0.05) lowered the heart rate (mean, 76 to 69 beats/min), aortic pressure (mean, 153/80-135/72 mm Hg), rate-pressure product (mean, 117-93 mm Hg/min), and coronary flow (mean, 114-94 ml/min). Coronary resistance (mean, 0.97-1.07 mm Hg x min/ml) and coronary flow related to the rate-pressure product (mean, 1.0-1.02 ml/mm Hg) showed no significant change after carvedilol treatment. Propranolol lowered the heart rate (mean, 76-64/min; P less than 0.05) and rate-pressure product (mean, 109-96 mm Hg/min; not significant). Aortic pressure (mean, 145/72-147/74 mm Hg), coronary flow (mean 109-101 ml/min), coronary resistance (mean, 1.1-1.2 mm Hg x min/ml), and coronary flow related to the rate-pressure product (mean, 1.12-1.19 ml/mm Hg) showed no significant change after propranolol administration. Following single application, carvedilol lowered the rate-pressure product more markedly than did propranolol on account of its acute blood-pressure-lowering effect. No differences in the hemodynamic effects of carvedilol and propranolol were found. Neither drug seems to influence the adaption of coronary flow to myocardial oxygen demand.

Adrenergic beta-Antagonists↗

Isolated rat cardiomyocytes as an experimental model for studying acute cardiotoxicity of cyclosporin A.

The acute cardiotoxicity of cyclosporin A was studied in isolated cardiac myocytes from adult rats. In an initial series of 7 animals, myocytes were incubated with concentrations of cyclosporin A ranging from 1 microgram/ml to 50 micrograms/ml. Shape changes of untreated cells, cells treated with cyclosporin A and cells treated with the solvent of cyclosporin A, Tween 80/ethanol, were evaluated. After 8 hours and 16 hours, respectively, of incubation 92 +/- 4.3% and 72 +/- 8.7% of the non-treated control cells were still rod-shaped. Cyclosporin A, however, in a concentration of 5 micrograms/ml decreased the number of rod-shaped cells (79 +/- 3.2% at 8 hours and 51 +/- 3.5% at 16 hours) in comparison to the solvent (94 +/- 3.5% at 8 hours and 76 +/- 5.8% at 16 hours, P less than 0.02). This effect became more pronounced with higher concentrations of cyclosporin A. On the other hand, Tween 80/ethanol alone in higher concentrations also led to a reduced number of rod-shaped cells. In a second series of 7 animals using Tween 80/ethanol and methanol as drug vehicles, myocytes were incubated for 16 hours with 15 micrograms/ml of cyclosporin A in a calcium containing medium (1 mM) or a calcium free medium (10(-4) M ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid). The number of remaining rod-shaped cells was higher in the calcium free medium as opposed to the medium containing calcium when the cells were exposed to cyclosporin A. It is concluded that in the applied model cyclosporin A at high concentrations has an acute cardiotoxic effect which in part appears to be calcium related.

Animals↗

Antiischemic and hemodynamic effects of intravenous isradipine, a new calcium antagonist, in coronary heart disease: a comparative double-blind cross-over study with nifedipine.

In a double-blind cross-over study, 10 patients with stable angina pectoris owing to coronary heart disease were investigated in supine position during rest and bicycle exercise for the effect of 0.4 mg of intravenous (i.v.) isradipine in comparison to 2 mg i.v. nifedipine on cardiac hemodynamics and myocardial ischemia. At rest, both drugs significantly decreased total peripheral resistance (TPR) and mean arterial blood pressure (MAP), whereas heart rate (HR) increased. The pressures and resistance of the pulmonary circulation remained uninfluenced at rest. During symptom limited-exercise, both medications reduced TPR despite an unchanged MAP. Mean pulmonary artery pressure decreased significantly after both medications, whereas right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP), and pulmonary vascular resistance (PVR) decreased significantly only after nifedipine. The improvement of mean ischemic ST-segment depression averaged 44 +/- 6% (mean +/- SEM, p less than or equal to 0.01) after nifedipine and 45 +/- 7% (p less than or equal to 0.01) after isradipine. The time until angina appeared increased after isradipine by 89 +/- 28% (p less than or equal to 0.05) and after nifedipine by 105 +/- 42% (p less than or equal to 0.01). Significant differences between the two medications appeared only for cardiac output (CO) at rest (p less than or equal to 0.05), during which state the increase after isradipine was higher than after nifedipine, and for exercise HR (p less than or equal to 0.01), during which state only nifedipine induced a significant increase in frequency. We conclude that at the chosen dosages the hemodynamic and antiischemic effects of isradipine are similar to the effects that occur after nifedipine.

Calcium Channel Blockers↗

Calcium overload in human giant cell myocarditis.

Myocardial calcium overload was observed in a patient with giant cell myocarditis. The myocardial calcium content estimated by atomic absorption spectrophotometry amounted to 120 mEq/kg dry weight, and the von Kossa stain disclosed multiple foci with patchy calcifications of myocardial fibres. Cytochemical examination of the ultrastructural calcium localisation using the phosphate-pyroantimonate method showed considerable variation in the subcellular calcium distribution. In normal myocytes calcium precipitates were confined to the inner leaflet of the sarcolemma, T-tubules, intercalated disks, and sporadically to mitochondria. In contrast, extensive calcification of mitochondria and loss of sarcolemmal calcium was evident in necrotic myocytes. A number of grossly normal myocytes also showed an increase of calcium precipitates in slightly swollen mitochondria. These findings suggest that myocardial calcium overload in this case started in viable myocytes and was not merely a secondary phenomenon occurring after cell death.

Calcinosis↗

[Effect of the calcium antagonist nisoldipine on coronary circulation and myocardial ischemia in temporary coronary occlusion].

Sixteen patients undergoing PTCA of a significant lesion of the left anterior descending coronary artery received either 0.3 mg nisoldipine or placebo intravenously. Immediately before and during balloon inflation the following parameters were measured: aortic pressure, post-stenotic pressure, coronary occlusion pressure, diastolic pulmonary artery pressure, coronary sinus flow (thermodilution), and intracoronary ECG. After placebo there were no statistically significant changes. Nisoldipine led to a decrease in aortic pressure from 109 +/- 12 to 93 +/- 11 mm Hg (p less than 0.05) before, and from 103 +/- 14 to 92 +/- 8 mm Hg (NS) during balloon inflation. In contrast, coronary occlusion pressure remained unchanged. Heart rate increased from 80 +/- 13 to 96 +/- 16/min before (p less than 0.05), and from 87 +/- 18 to 97 +/- 17/min during balloon inflation (NS). Coronary sinus flow was increased from 95 +/- 16 to 116 +/- 13 ml/min before balloon inflation (p less than 0.01), and from 70 +/- 25 to 86 +/- 26 ml/min during balloon inflation (NS). ST-segment depression or elevation, severity of angina pectoris, and the diastolic pulmonary artery pressure remained unchanged. Thus, 0.3 mg nisoldipine led to a peripheral vasodilatation. While the aortic pressure decreased, coronary occlusion pressure remained unaffected. This could be explained by a marked dilatation of collateral vessels due to nisoldipine. However, myocardial ischemia remained unaffected as a result of the constant coronary occlusion pressure.

Adult↗

[Rupture and fragmentation of a polyethylene terephthalate balloon catheter in a calcified coronary artery stenosis].

We report a case of rupture and fragmentation of a PET-balloon catheter during percutaneous transluminal coronary angioplasty of a calcified LAD-obstruction. When the insufflation pressure was increased to 12 atm, the balloon ruptured. During withdrawal of the balloon catheter the tip of the shaft and a fragment of the balloon tore off and remained within the atheroma. Emergency operation was necessary to remove the fragments and to prevent a large myocardial infarction. Although this is an unusual complication of PTCA, care should be taken when PET-balloon catheters are used in calcified coronary obstructions.

Adult↗

[The effect of electromagnetically produced shock waves on calcified, stenosed aortic valves].

To determine if electromagnetically generated shock-wave lithotripsy has potential application for treatment of stenotic, calcified aortic valves, 38 cusps of surgically excised human aortic valves were studied. Valves were weighed, photographed, and calcium deposition was determined by x-ray. Stiffness was determined by palpation and by measuring the pressure gradient generated in a perfusion system. Valves were exposed to shock waves at 16 or 18 kV with 200 or 400 impulses each. Twenty valves reacted to exposure to shock waves with a reduction in pressure gradient of 1.9 +/- 2 cm H2O. Calcified valve area was reduced by 3.5 +/- 1.3 mm2. Valves without changes in pressure gradient showed a reduction of 7.1 +/- 2 mm2 of calcified valve area. There was no significant difference in weight loss. Using a small focus (4 mm) there was a significant reduction in pressure gradient and calcified valve area, but not in weight; with a large focus (8 mm) reduction in calcified valve area, gradient, and weight was significant (p less than 0.05). Changes in valve stiffness were independent of weight loss and reduction in calcified valve area. In conclusion, shock-wave lithotripsy is capable of reducing stiffness of calcified aortic valves, presumably by fragmentation of tissue calcium deposits.

Aortic Valve↗

[Eccentric coronary stenoses--definition and incidence in coronary angiograms].

The frequency of "eccentric" stenoses was determined in 676 coronary angiograms, which proved to be useful to classify stenoses according to their position (central, eccentric), as well as to the form of residual lumen (round, not round). The results for 616 stenoses which could be evaluated for both position and form were: 30% (183/616) centrally located with round residual lumen; 10% (60/616) centrally located with no round residual lumen; 41% (255/616) eccentrically located with round residual lumen; 19% (115/616) eccentrically located with no round residual lumen. These results are in agreement with previous autopsy findings. The location and form of coronary stenoses may have different meanings: the prevalent round form of residual lumina (71% of all evaluated stenoses) may characterize a normal growing of stenoses, while no round forms might indicate complications such as ruptures with hemorrhage within plaques. The prevalent eccentric location of residual lumina (63% of all evaluated stenoses) may reflect a tendency to dynamic coronary tone within the respective coronary stenosis. This assumption is supported by similar frequencies of dilatative or constrictive responses in patients with coronary artery disease. Individual prognoses, however, with respect to coronary tone or coronary reactions cannot be predicted from morphology.

Coronary Angiography↗

Retardation of development and progression of coronary atherosclerosis: a new indication for calcium antagonists?

Development of atherosclerotic lesions in animals, preferrably induced by a high-cholesterol diet, can be successfully suppressed by calcium channel blockers such as verapamil, nifedipine, nicardipine and diltiazem. The issue of a beneficial effect of calcium channel blockers on human coronary atherosclerosis is however not yet settled. At present, three prospective randomized clinical trials with calcium channel blockers (Nifedipine, Verapamil, Nicardipine) are being conducted (INTACT, FIPS, Study of the Montreal Heart Institute). Target variable for assessment of progression in these studies is the severity of coronary atherosclerosis evaluated by angiography both at entry into the study and after 2-3 years of treatment. A total of 445 patients after coronary bypass surgery (CABG) were entered in FIPS (Frankfurt Isoptin Progression Study) and randomly allocated to either verapamil 120 mg t.i.d. or placebo. The extent of coronary atherosclerosis is assessed by repeat angiography both 1 year and 3 years after randomization. Three vessel regions are evaluated separately. 1. Native vessels without bypass grafts and segments distal to the peripheral graft anastomosis ("core region") 2. Segments bridged by bypass grafts and 3. Bypass grafts. The 1-year follow-up was completed by 162 patients (Group A = 80 patients; Group B = 82 patients). There was a homogeneous distribution in the two groups for all clinical variables, graft patency rates, and the incidence of clinical events (myocardial infarction, need for cardiac surgery or PTCA, cardiac death). The overall progression rate of atherosclerosis in the first year was expectedly low.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

[Effects of transluminal angioplasty on the prognosis after non-Q-wave infarction].

The long-term prognosis in non-Q-wave infarction (NQWI) has proven to be unfavorable due to frequent cardiac events. This study aimed at defining the impact of transluminal coronary angioplasty (TCA) on the prognosis, angina pectoris, ischemic ECG changes, and fitness for work in NQWI. TCA was performed on 114 patients at a mean of 3.8 months after NQWI with a success rate of 78% (success vs failure = 89 vs 25 patients). Clinical follow-up was obtained in 96% of patients at a mean of 49 months after successful TCA or 53 months after unsuccessful TCA, and 90% of patients had angiographic follow-up. Recurrent stenosis was recorded in 17 patients (21%): seven had a second TCA, one a bypass operation, and nine showed only lowgrade stenosis and were treated medically. Another seven patients had dilatation of a new stenosis. Seventy percent of the unsuccessfully dilated patients were subsequently treated with surgery. Differences in coronary morphology between both groups could be responsible for the success of the intervention, but not for the parameters analyzed. Reinfarction and death were found to occur more frequently during the follow-up period after unsuccessful angioplasty and exclusively in those who were treated medically. Most patients with unsuccessful TCA had a long-term benefit regarding improvement in symptoms, exercise-induced ischemia, and fitness for work. Coronary revascularization should consequently be indicated in patients with NQWI for prognostic reasons. The favorable long-term results observed regarding symptoms, myocardial ischemia, and fitness for work give evidence supporting coronary angioplasty as the primary revascularization procedure, if coronary anatomy permits.

Angioplasty, Balloon, Coronary↗

[Practical experiences with wheelchair sports of paraplegic patients].

The group of wheelchair sportsmen presented see their field of activity not only in terms of practising sports with its manifold positive effects but also in terms of providing information and care for hospitalized paraplegic patients and/or recently discharged rehabilitees. The article is based on the answers to a questionnaire developed by the sports medical counselling office in Zwickau. Severely disabled persons, too, take pleasure in their improved fitness and performance.

Humans↗