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Biomedical subjects

M Kaltenbach

Publications and source records attributed to M Kaltenbach.

At least 109 records · Page 6Linked to original sources
PubMed1990

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↗
PubMed1990

Management of hypertrophic cardiomyopathy.

Therapy of hypertrophic cardiomyopathy aspires to reduce symptoms, increase exercise tolerance, retard or prevent disease progression, and improve prognosis. Medical treatment with calcium antagonists and suppression of rhythm disturbances with amiodarone seem to be most effective. In patients who show no improvement, surgical treatment must be considered.

Cardiomyopathy, Hypertrophic↗
PubMed1990

Experimental balloon valvuloplasty of fibrotic and calcific mitral valves.

This study evaluated the mechanism of valvular area expansion during single- and double-balloon valvuloplasty in fibrotic and calcific mitral valves. Special interest was focused on the morphological features of the valves treated. Mitral valves that appeared unsuitable for commissurotomy were excised in toto at the time of mitral valve replacement in 15 patients. The excised valves were mounted in a fluid-filled chamber with a window for photographic evaluation. The chamber was perfused continuously to ensure maximal valvular opening. The valve was photographed, and the orifice area was measured before and after balloon expansion. In addition, the specimens were examined macroscopically and radiographically with regard to calcium content and degree and localization of fibrosis. These data were correlated with splitting of commissures and with rupture of leaflets. Nine valves were fibrotic, and six were calcific. Dilatation was performed first with a single-balloon catheter (diameter, 2 cm) and then with a double-balloon catheter (diameter, 2 and 1.5 cm). After dilatation with one balloon, the average mitral valve area increased from 0.79 to 1.09 cm2, and with two balloons, average area increased to 1.59 cm2. The single-balloon technique caused commissural splitting in nine valves, stretching in three, partial leaflet rupture in one, and no change in two. After the double-balloon technique, commissural splitting occurred in 12 valves and three leaflets were ruptured where severe fibrosis and calcification were mainly located within the commissures. As a rule, after dilatation with the single-balloon technique, the remaining stenosis was still severe, and after dilatation with the double-balloon technique, the remaining stenosis was moderate.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcinosis↗
PubMed1990

[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↗
PubMed1990

[Effect of verapamil on rate of restenosis following transluminal angioplasty of renal artery stenoses].

This prospective double-blind randomized study examined the effect of verapamil on restenosis after angioplasty of renal artery stenoses. 31 patients received placebo or 120 mg verapamil two or three times daily until the appointed day of the control angiography after 3 months. All patients received 1.5 g aspirin per day. In the control group (13 stenoses, 12 patients) the degree of stenoses increased from 35 +/- 15% immediately after PTA to 41 +/- 21% at repeat angiography 3 months after PTA, in the verapamil group (20 stenoses, 14 patients) from 35 +/- 16% to 43 +/- 22% (ns). Stenoses recurred in 23% of the stenoses in the placebo group and in 20% of the stenoses in the verapamil group (ns). 5 patients, who interrupted the therapy, were excluded from the evaluation. In the conclusion, verapamil does not decrease the incidence of restenosis after PTA of renal artery stenoses during concurrent therapy with aspirin.

Adult↗
PubMed1990

[Rotation angioplasty of chronic coronary artery stenosis].

Coronary artery occlusion of more than six months duration can only rarely be recanalized with conventional techniques. For this reason, rotational angioplasty, which has been successfully applied for occlusion of peripheral arteries, has been employed in modified form for recanalization of chronic coronary artery occlusion. Rotational angioplasty is based on the concept that the slowly revolving, dull and relatively thick head of the flexible rotation catheter will seek the path of least resistance which, even in the case of relatively old arterial occlusions, mostly represents thrombotic material. The elastic, high-torque rotational catheter constructed of several V2A spiral steel wires has an interior lumen for insertion of exchange guidewires up to 0.014" and injection of contrast medium and an olive-shaped head of V2A steel with a diameter of 1.3 to 1.6 mm. A protection catheter made of polyethylene with metal markers and conically-tapered tip provides variable stiffness of the rotating catheter and protection of the endothelium in the proximal vascular segment. The slow rotation of 200 r.p.m. is performed with a small electric motor. Between April 1987 and February 1988, rotation angioplasty was performed in 20 patients, 17 with occlusion of the right coronary artery, two with occlusion of the left anterior descending artery and one with bypass graft occlusion to the left anterior descending artery in whom a conventional guidewire through the chronic occlusion could not be advanced. The duration of occlusion, based on previous angiograms anginal complaints or myocardial infarction, ranged from one month to twelve years, in twelve patients more than six months. In all patients, the indication for revascularization was clearly established.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[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↗
PubMed1990

[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↗
PubMed1990

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↗
PubMed1990

[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↗
PubMed1990

[Comparison of the oxygen deficit and ischemia pain threshold in patients with silent and symptomatic myocardial exercise-induced ischemia].

In 39 patients with angiographically documented coronary artery disease and silent or symptomatic myocardial ischemia under exertion it was investigated if there is a difference in forearm skeletal muscle ischemia and ischemic pain threshold. The degree of myocardial ischemia was determined by plethysmographically measured reactive hyperemia. In 12 asymptomatic and eight symptomatic patients maximal reactive hyperemia was induced by ischemic work in the forearm skeletal muscle. After termination of ischemia there was a significantly higher reactive hyperemia at 20, 90, and 180 s in the asymptomatic patients. Furthermore, nine asymptomatic and 10 symptomatic patients underwent symptom-limited ischemic work until weakness or pain developed. Under these conditions reactive hyperemia as a parameter of oxygen deficiency was higher in the asymptomatic patients. The difference was not statistically significant. There was, however, a significantly higher incidence of ischemic pain in the symptomatic patients. It can be concluded that patients with asymptomatic myocardial ischemia tolerate a higher oxygen deficit in the working forearm and have a higher pain threshold than patients with symptomatic ischemia.

Angina Pectoris↗
PubMed1990

[Coronary angioplasty--can the risk of recurrence be predicted on the day of surgery? A prospective study].

Data from a retrospective study defining seven parameters of increased risk of restenosis after successful transluminal coronary angioplasty (high-grade stenoses, long stenoses, eccentric stenoses, use of high pressure, extended time of balloon inflation, stenoses in obese patients, stenoses in patients without a history of smoking) were fed into a computer. A discriminant analysis was made and an algorithm for prediction of restenosis was defined. The validity of prediction was prospectively tested in 101 patients. In 80/101 (79.2%) prediction was possible; in 21/101 (20.8%) it was not possible. In 15/80 patients (18.8%) the prediction was: "restenosis probable"; in 65/80 patients (81.2%): "restenosis not probable". After 4.4 months 93/101 patients (92.1%) had an angiographic follow-up. The prediction "restenosis" proved to be correct in 13/15 patients (86.7%), and the prediction "no restenosis" was correct in 56/65 patients (86.2%). It is concluded that in the majority of patients the risk of restenosis can be predicted immediately after the intervention.

Adult↗
PubMed1990

[Decreased vagal tone in hyperkinetic heart syndrome?].

Increasing amounts of atropine (0.03 mg + 0.07 mg + 0.01 mg + 0.25 mg + 0.5 mg + 1.0 mg + 1.5 mg; sigma = 3.5 mg, interval between injections: 30 min) were injected intravenously in a cumulative manner in five patients with hyperkinetic heart syndrome and in seven healthy volunteers. The heart rate increased from 93 to 127 beats per min in patients, and from 63 to 104 beats per min. in controls. The diastolic blood pressure slightly increased in both groups, whereas the systolic blood pressure did not change significantly. The accommodation diminished from 6 to 2 dioptries in patients, and from 8 to 5 dioptries in controls. Salivary flow fell from 1.6 to 0.1 g/min in patients with hyperkinetic heart syndrome, and from 1.3 to 0.1 g/min in control persons, respectively. The maximum occupancy of muscarinic receptors (m2-glandular), as measured in plasma specimens by means of a radioreceptor assay, reached more than 80% in each group. The dose-response-curves of atropine were highly comparable in patients and controls. It is concluded that the effects of atropine are essentially the same in patients with hyperkinetic heart syndrome and in healthy control persons. There is no evidence for a diminished vagal tone in such patients.

Adult↗
PubMed1990

[Long-term clinical follow-up after coronary dilatation].

To determine the long-term clinical course after percutaneous transluminal coronary angioplasty (PTCA), 841 patients, 615 with successful PTCA and 226 without, were restudied by questionnaire 2-9 years after the intervention. After successful PTCA a lasting symptomatic improvement was seen in 78% of patients vs 55% of patients without successful PTCA (p less than 0.0001). The probability of myocardial infarction 8 years after successful PTCA was 6% vs 24% after unsuccessful PTCA (p less than 0.0005). The 8-year survival probability (non-cardiac deaths excluded) was 95.7% in patients with demonstrable PTCA success, and 92.0% in patients without (p less than 0.05). Similar significant differences in favor of patients with successful PTCA were seen in the long-term prognosis of patients with single-vessel disease (n = 580). It is concluded that a long-term improvement of the cardiac prognosis by successful PTCA is probable.

Angioplasty, Balloon, Coronary↗
PubMed1989

[Life-threatening complications of ergometry].

During the four most common ergometric exercise tests--bicycle ergometry seated and lying, step exercise testing and treadmill ergometry--such life-threatening complications as ventricular fibrillation, pulmonary edema or myocardial infarction occur to a varying degree. As a typical complication of bicycle ergometry with the patient lying, pulmonary edema, which can be explained by an increase in the venous return in the supine patient, has been observed in 1:29,000 cases. Ventricular fibrillation is particularly common in treadmill ergometry, possibly as a consequence of CNS-derived stimuli provoking arrhythmias due to this type of ergometry which may cause anxiety in some patients. Myocardial infarction, and also death--usually as a result of acute infarction--are also seen much more commonly in treadmill exercise testing (1:2,800 and 1:20,000, respectively) than in bicycle ergometry with the patient seated or supine. The step exercise test is associated with an infarction rate of 1:43,000, and a mortality rate of 1:128,000, and is thus a comparatively safe form of exercise testing. Maximum loading of the patient and the mode of the exercise test (test protocol) appear to have no influence on the complication rate. A careful prior examination including history-taking, the presence of a physician and a standby defibrillator are a must.

Cause of Death↗
PubMed1989

[Piretanide in chronic and acute decompensated heart failure. Effect on hemodynamics and vasoactive hormones].

Eight patients with chronic heart failure classified as NYHA class II to III (group 1) and nine patients with acute decompensated heart failure classified as NYHA class IV (group 2) were treated with piretanide at a dosage of 12 mg administered intravenously. In both groups the level of prostaglandine PGE2 as well as plasma renine activity significantly increased prior to the onset of diuresis. The percentage increase was more pronounced in group 1 which had lower baseline values. With a time-lag, the norepinephrine plasma level also increased significantly. During the first 30 minutes there was only little effect on blood pressure, pulmonary artery pressure and cardiac output in patients with chronic heart failure (group 1). Only after 60 minutes there was a significant decrease in mean pulmonary artery pressure (from 39 +/- 17 to 33 +/- 18 mm Hg; p less than 0.05). In patients with acute decompensated heart failure (group 2) piretanide led to a significant reduction in mean pulmonary artery pressure (from 42 +/- 13 to 37 +/- 12 mm Hg; p less than 0.05) within 15 minutes after administration, i.e. even prior to the onset of diuresis. Thus, the administration of piretanide had a positive effect on hemodynamics in patients with chronic as well as in patients with acute decompensated heart failure. Significant improvement prior to diuresis onset, however, was only found in patients with acute decompensated heart failure. These effects may be explained by a stimulation of prostaglandines which promote vasodilation. They are increased by the diuresis.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1989

[Aortic aneurysm after dilatation of aortic isthmus stenosis].

An aneurysm in the region of the dilatation occurred in two of 23 patients (a 17-year-old boy and a 29-year-old woman) three and one years, respectively, after balloon dilatation for coarctation of the (thoracic) aorta. The aneurysm in the boy was small (18 mm diameter) and he was symptom-free so that no operation is as yet indicated. But the woman had progressively increasing backache after physical exertion and the aneurysm was 4 cm in diameter. Therefore, the aneurysm and coarcted segment were resected and a Dacron prosthesis interposed. As the ultimate value and risk of balloon dilatation of coarctation of the aorta cannot as yet be definitively judged, all patients should be carefully and repeatedly examined over a longer period.

Adolescent↗