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Biomedical subjects

M Kaltenbach

Publications and source records attributed to M Kaltenbach.

At least 73 records · Page 4Linked to original sources
PubMed1992

Nonoperative closure of the patent ductus arteriosus: the Frankfurt experience.

Nonoperative closure of patent ductus arteriosus (PDA) by means of Ivalon plugs (according to the technique of Porstmann) was performed in 101 patients. Sixty-five patients were symptomatic, the Q p/Q s ratio exceeded 1.5 in 56 patients, and pulmonary hypertension (mean pulmonary artery pressure greater than 20 mmHg) was present in 50 patients. In 100/101 patients the PDA could be closed successfully. Ninety-nine patients were without any evidence of residual left-to-right shunt. In one patient a hemodynamically insignificant left-to-right shunt was found with color Doppler echocardiography. Complications were pulmonary embolism due to plug dislocation in two patients (12th and 14th patient; 2 and 7 weeks after the procedure, respectively). One of these patients underwent elective surgery with patch closure of the ductus and removal of the embolized plug. In the other patient the ductus was successfully closed with a second larger plug while the first plug was left in a peripheral pulmonary artery. Surgical revision of the femoral artery was required in six and blood transfusion in two patients. Deep venous thrombosis developed in two patients. During follow-up (total follow-up time more than 200 patient years) no late complications were observed. In conclusion, transfemoral catheter closure of PDA by means of Ivalon plugs is an effective method. It is applicable to adolescents and adults with a low complication rate. The ductus can be closed without residual left-to-right shunt. Long-term results are excellent.

Adolescent↗
PubMed1992

Effect of propranolol and disopyramide on left ventricular function at rest and during exercise in hypertrophic cardiomyopathy.

In 19 patients with hypertrophic cardiomyopathy (15 males, 4 females, mean age 49.2 +/- 10.8 years) left ventricular function was studied with radionuclide ventriculography at rest and during exercise in a crossover design without intervention and after disopyramide and propranolol treatment. 15 of the 19 patients had a resting or latent intraventricular gradient of more than 30 mm Hg. Left ventricular function at rest and during exercise was evaluated before medication, 90 min after oral administration of 200 mg disopyramide or 160 mg propranolol and after 3 weeks of oral therapy with disopyramide 200 mg 2 times a day or propranolol 80 mg 4 times a day. After long-term treatment with disopyramide, resting ejection fraction decreased from 72 +/- 12 to 69 +/- 14% (p less than 0.01) and peak ejection rate (PER) decreased from 3.46 +/- 135 to 3.24 +/- 65 end-diastolic volume (EDV).s-1 (p less than 0.01). Peak filling rate (PFR) at rest decreased from 3.01 +/- 0.8 to 2.77 +/- 0.63 EDV.s-1 (p less than 0.05). Time to peak filling rate (TPFR) at rest and during exercise after acute and chronic therapy did not change compared to control values. Acute and long-term administration of propranolol lead to a significant reduction in heart rate at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1992

Can the coronary atherosclerotic process be influenced by calcium antagonists?

Cell culture experiments and various animal models have shown that calcium antagonists can inhibit atheroma development. A number of antiatherosclerotic mechanisms have been proposed and the promising results of these in vitro and animal experiments prompted clinical trials. Retrospective analyses indicated that verapamil might retard disease progression and the development of new stenoses. Prospective clinical studies, however, have revealed no effect by calcium antagonists on pre-existing coronary stenoses (> or = 20%) and it is suggested that the study duration (2 to 3 years) may have been too short and that advanced stages of atheromatous disease are not influenced by calcium antagonists. Current data suggest that only early stages of coronary atheromatosis may be affected by treatment with calcium antagonists; however, optimum drug, dosage and suitable patients are yet to be defined.

Animals↗
PubMed1992

[Randomized comparison between collagen administration and pressure dressings for occlusion of the arterial puncture after coronary angiography and coronary dilatation].

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 both groups. The average compression time was 4.3 min in group A and 42.3 min in group B (p < 0.001). In group A, 1/50 patients required pressure dressing compared to 50/50 patients in group B. Bleeding was not observed in group A, but was observed in 6/50 patients in group B. The time to ambulation was 6.4 (range, 4-12) h in group A and 21.6 (range, 10-48) h in group B (p < 0.001). Hematomas with a diameter of > 6 cm developed in 4/50 patients in group A and in 11/50 patients in group B (p < 0.05). 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.

Angioplasty, Balloon, Coronary↗
PubMed1992

[Myocardial function before and after reopening of chronic coronary occlusion].

To assess the myocardial function before and after reopening of chronic coronary artery occlusions, 20 patients were investigated at rest and during exercise with ECG and equilibrium radionuclide ventriculography. The recanalisation of the chronically occluded vessel was carried out by means of Rotacs-catheter in 17 patients, of a guide wire enforced by recanalisation-catheter in 2 patients and of a thin guide wire alone in 1 patient, always followed by conventional balloon angioplasty. After successful PTCA the average coronary artery stenosis diameter decreased from 100% to 34 +/- 6%. Angina pectoris and/or dyspnea observed during exercise were improved in 83% of the patients. The radionuclide global left ventricular ejection fraction at rest increased from 55 +/- 9% to 59 +/- 10% (p < 0.05), and during exercise from 52 +/- 12% to 61 +/- 12% (p < 0.05). The improvement in global ejection fraction at rest was more pronounced in 5 patients, who suffered from angina pectoris at rest before PTCA (from 56 +/- 4% to 65 +/- 9%, p < 0.05). It is concluded that reopening of chronically occluded coronary arteries in properly selected patients leads to a significant improvement of the global left ventricular function at rest and during exercise.

Adult↗
PubMed1992

Concept graphics: a language for medical knowledge.

This paper makes a case for Concept Graphics, a novel form of medical knowledge representation. Concept Graphics are assemblies of icons each of which has a precise meaning. Individual icons are metaphors of the object or process they represent. Concept Graphics are analogs of pathological situations, their symptoms, signs and other relevant components necessary for a diagnosis. We propose three principal areas of application for Concept Graphics: medical education, medical records management and research based on medical records. Our earlier work in medical education showed a clear advantage in using Concept Graphics in parallel with text of equivalent information content, over text alone. A Concept Graphics based intelligent tutoring systems (ITS) is being developed. In the area of medical records management we are developing a system for the rapid identification of relevant records based on rapid visual screening. The Concept Graphics based system can reveal properties common to specific groups of records. As such the graphics are a research tool.

Computer Graphics↗
PubMed1992

[Cholesterol lowering and life expectancy: a critical evaluation].

Numerous studies have confirmed a positive correlation between serum cholesterol levels and the occurrence of coronary artery disease. Lowering cholesterol by 1% is accompanied by a reduction of coronary events by 2%. The rate of fatal coronary events is not significantly influenced. Coronary angiography demonstrated only a mild average reduction of coronary lesions after cholesterol-lowering therapy. This might be explained by the low lipid content of a coronary plaque (5-15%). The majority of intervention trials revealed an increase of the extracardiac mortality in treatment groups. Thus, up to the present, it remains unproven that cholesterol-lowering therapy leads to an increase in life expectancy.

Cholesterol↗
PubMed1991

[Changes in the blood and plasma volumes during diagnostic angiocardiography. Differences between high- and low-osmolality contrast media].

Changes in blood and plasma volumes were investigated in the course of diagnostic cardiac catheterizations, comparing the effect of a high and a low osmolar contrast medium in 30 patients (5 women and 25 men; mean age 53 [19-76] years) with coronary heart disease (n = 27) or valvular defect (n = 3). Using a randomized, double-blind protocol 15 patients received amidotrizoic acid (2.1 osmol/kg; mean dosage 166 +/- 68 or 2.2 +/- 1.1 ml/kg), while 15 patients received iopamidol (0.8 osmol/kg; mean dosage 154 +/- 78 ml or 2.1 +/- 1.0 ml/kg). The indocyanine-green method and the haematocrit were used to measure blood and plasma volumes immediately before and after the angiocardiography. Blood volume after amidotrizoic acid injection increased by a mean of 4.9% (228 +/- 242 ml) and by 0.4% (17 +/- 197 ml) after iopamidol (P less than 0.05). Plasma volume increased by a mean of 11.8% (331 +/- 150 ml) after amidotrizoic acid and 5.7% (157 +/- 97 ml) after iopamidol (P less than 0.01). The increase in plasma volume correlated with the dose of contrast medium: 2 ml per ml amidotrizoic acid (r = 0.93) and 1 ml per ml iopamidol (r = 0.82).--During angiocardiography blood and plasma volume may increase by up to 500 ml, an increase which depends not only on dosage but also on the osmolality of the injected contrast medium.

Adult↗
PubMed1991

[20 years of selective coronary angiography (1968-1987). The indications, results and therapeutic consequences].

10,975 diagnostic left-heart catheterizations, performed between 1968 and 1987 in 8,436 men and 2,539 women, were analysed regarding indication, results and therapeutic implications. 6,974 patients (64%) had coronary heart disease, 2,573 (23%) a valvar defect and 849 a cardiomyopathy. The proportion of patients with coronary heart disease increased from 21% to 74% during the 20-year period, while that of patient with valvar defects fell from 52% to under 19%. Severe cardiac complications in relation to the procedure occurred in 0.88%, ending fatally in 8 patients (0.07%). 61% of patients with coronary heart disease and 31% of those with valvar defects were treated conservatively. Percutaneous transluminal coronary angioplasty (PTCA) gradually became more common after its introduction in 1977. In 1987, PTCA was indicated as often as a bypass operation.

Age Factors↗
PubMed1991

Impairment of left ventricular function during coronary angioplastic occlusion evaluated with a nonimaging scintillation probe.

Impairment of left ventricular function during controlled myocardial ischemia induced by coronary angioplasty has been reported from angiographic and echocardiographic studies. Ejection fraction, peak ejection, peak filling rates, and end-systolic and end-diastolic volumes were investigated before, during and after coronary occlusion on-line with a nonimaging scintillation probe. The study consisted of 18 patients (mean age 59 +/- 10 years) with coronary artery stenosis of greater than 70%. During balloon inflation of 60 seconds' duration, coronary occlusion pressure was 31.6 +/- 12 mm Hg. There was no significant change in heart rate. Delay between first and second dilatation was 109 +/- 63 seconds. Ejection fraction decreased from 53 +/- 16 to 40 +/- 12% (first dilatation, p less than 0.01) and to 39 +/- 14% (second dilatation, p less than 0.01) and recovered to 51 +/- 16% 5 minutes after the second dilatation. Peak ejection rate was significantly reduced during the first and second balloon inflations. Peak filling rate decreased from 2.5 +/- 0.8 to 2.0 +/- 0.7 end-diastolic volume.s-1 (first dilatation, p less than 0.01) and to 1.8 +/- 0.7 end-diastolic volume.s-1 (second dilatation, p less than 0.01) and remained reduced at 2.2 +/- 0.7 end-diastolic volume.s-1 (p = not significant) at 5 minutes after the second dilatation. End-systolic and end-diastolic volumes increased significantly during the first and second dilatations and returned to normal after dilatation. It is concluded that short, controlled myocardial ischemia during coronary angioplasty leads to a decrease in systolic and diastolic left ventricular function. Sequential dilatations do not further decrease function if a sufficient interval is kept.

Angioplasty, Balloon, Coronary↗
PubMed1991

[Serum cholesterol and coronary sclerosis].

Among both the general population and physicians, there is considerable uncertainty as to the significance of elevated cholesterol levels. Many laboratories consider all values above 200 mg/dl to be abnormal or undesirable. Taking the case of a 66-year-old lady doctor as an example, arguments against such an undifferentiated view are advanced. It is concluded that cigarette smoking continues to be the major risk factor for coronary heart disease, and every effort should be made to reduce it. Elevated cholesterol levels alone usually have no clinical significance; they should be assessed only in conjunction with other blood parameters, but also with age and sex.

Aged↗
PubMed1991

[Recanalization of chronically obstructed coronary vessels using ROTACS (low-speed rotational angioplasty. Early and long-term results in 152 patients following unsuccessful conventional angioplasty].

Total coronary artery occlusion is the main limiting factor of non-surgical recanalization procedures. With conventional methods, recanalization of total occlusions older than 6 months has a low success rate. Low-speed rotational angioplasty (ROTACS, Osypka, Medtronic) was employed in 152 patients with chronic coronary occlusions in whom conventional guide wire techniques failed. The average success rate was 60% and, although not correlated to site of occlusion, revealed a clear correlation to the duration of the occlusion: 93% (1-3 months), 74% (4-6 months), 52% (6-12 months) and 8% (greater than 12 months). Emergency surgery was needed in 2 patients in whom an attempt was made to recanalize an occluded LAD branch. In both cases, the occlusion was located in the immediate vicinity of the main trunk of the left coronary artery. Thereafter, this anatomical situation was considered a contraindication and no further complications occurred in the subsequent 120 patients. Among the 152 patients, no deaths, no myocardial infarction and no perforation of the vessel wall occurred. Long-term results were monitored by angiography in 95% of successfully treatment patients; good results were documented in 72%.

Angioplasty, Balloon↗
PubMed1991

[Aortic valve insufficiency. Diagnosis, course, therapy].

A radionuclide ventriculographic procedure for the accurate quantification of aortic insufficiency has been developed, and its use in follow-up, pharmacotherapy and surgical planning tested. In 28 patients, follow-up over a period of 20 months revealed only slow progression of the chronic aortic insufficiency; worsening of the symptoms leading to the need for valve replacement was associated with a rapid deterioration of objective parameters. In patients with a stable condition, captopril administered for 4-8 weeks failed to reduce left ventricular overload to any significant extent, while reduction in volume overload was observed in patients with accompanying congestive heart failure or systemic hypertension. Clinical analysis revealed that, as a rule, the indication for valve replacement must be based on follow-up examination. If radionuclide ventriculography reveals a disproportionate enlargement of the ventricle, surgery is indicated even in the absence of symptoms.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1991

[Successful directional coronary atherectomy after futile attempts at balloon dilatation].

Coronary arteriography revealed severe stenoses of the proximal part of the anterior interventricular branch with normal ventricular function in two patients (aged 42 and 38 years) with stable angina and ischaemia reaction in the exercise ECG. In the first patient it was a short spur-like 80% narrowing. But percutaneous balloon angioplasty failed to change the angiographic appearance. In the other patient there was an eccentric, apparently elastic, 90% stenosis, about 10 mm long. Here, too, balloon angioplasty had failed. Subsequently directional coronary atherectomy in both patients achieved removal of the stenosis with lasting clinical improvement. Atherectomy should be considered in similar cases after failed balloon dilatation.

Adult↗
PubMed1991

The effect of cyclosporine on electrically paced isolated rat cardiomyocytes.

The acute cardiotoxicity of cyclosporine was investigated in isolated cardiomyocytes from adult rats. In a first study, myocytes were incubated with CsA ranging from 1 to 10 micrograms/ml and paced by electrical-field stimulation. After 30 min of stimulation the number of surviving rod-shaped myocytes was significantly reduced at 2.5 micrograms/ml (77.9%) and 5 micrograms/ml CsA (64.2%) as compared with the drug vehicle methanol (88.8%, P less than 0.05) with a further decrease at 10 micrograms/ml CsA (30.1% vs. 81.2%, P less than 0.005). In a second study, with the use of digital image processing of fura-2 fluorescence, the mean intracellular free calcium concentration, integrated over 1 sec, of single myocytes in the presence of 5 micrograms/ml CsA, the solvent methanol, or pure Krebs Ringer Hepes buffer was measured. Starting 2 Hz field stimulation increased the intracellular free calcium concentration from 100.1 to 177.9 nM in buffer and from 145.7 to 200.6 nM calcium with methanol. In contrast, there was a 3-fold increase of the intracellular free calcium concentration with 5 micrograms/ml CsA from 128.8 to 376.1 nM calcium. The intracellular free calcium during electrical stimulation was significantly higher with CsA than with the solvent (376.1 nM vs. 200.6 nM, P less than 0.001). In a further study, myocytes were incubated with calcium ranging from 0.5 to 8 mM calcium in the presence of 5 micrograms/ml CsA or the solvent methanol and electrically stimulated. Here, with increasing extracellular calcium the number of rod-shaped myocytes decreased significantly with CsA as compared with the solvent (P less than 0.02). The data suggest that CsA exerts a dose-dependent toxic effect on isolated rat cardiomyocytes that depends on the extracellular calcium concentration. There is direct evidence that CsA increases the intracellular free calcium concentration in rat cardiomyocytes.

Animals↗
PubMed1991

Recanalization of chronic coronary occlusions by low speed rotational angioplasty (ROTACS).

From 1988 to 1990 chronic coronary occlusions were treated with a newly developed slowly rotating angioplasty system (ROTACS), which is designed for atraumatic passage of arterial obstructions. In all 152 patients (mean age 55 years, ranging from 29 to 78 years) attempts to recanalize the coronary occlusion with conventional guidewire systems had failed. In 74/152 patients the age of the occlusion could be estimated because of a previous angiogram or clinical event. It ranged from 1-192 months (median 6 months, mean value 14 months; in 20% of patients it was 1-3, in 37% 4-6, in 28% 7-12, and in 15% greater than 12 months). The occlusion was localized in the right coronary artery (RCA) in 86 cases, in the left anterior descending coronary artery (LAD) in 37 cases, and in the circumflex branch of the left coronary artery in 17 cases. Eleven bypass occlusions were treated. One patient had a LAD and RCA occlusion. Out of 152 patients 84 could be recanalized. The success rate rose with experience from 30% to 60%. It was 55% in the LAD, 52% in the RCA, 70% in the circumflex branch, and 63% in bypass grafts. The success rate in relation to the age of the occlusion was 93% in occlusions of 1-3 month duration, 74% in occlusions of 4-6 months duration, 52% in occlusions of 6-12 months duration, and 8% in occlusions older than 12 months. Seventy-six of the successfully treated patients underwent follow-up angiography after 4 months. In 56/76 (74%) the vessel remained open. Twenty-two patients (29%) had restenosis that was successfully dilated in 21 patients. Twenty patients (26%) had reocclusion. Thus, the angiographically determined long-term success rate was 72%. Emergency operation was necessary in two patients in whom reopening of the LAD was attempted although the occlusion was located directly at the take-off of the LAD from the left main. Since this type of occlusion was consequently considered a contraindication, no further serious complications occurred. There was one myocardial infarction, no death, no vessel wall perforation or other complications in the 152 patients. It is concluded that low speed ROTACS is a safe technique that can be applied in chronic coronary occlusions even if the duration of occlusion exceeds 6 months.

Adult↗