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Biomedical subjects

M Kaltenbach

Publications and source records attributed to M Kaltenbach.

At least 37 records · Page 2Linked to original sources
PubMed1995

Urinary excretion of cicletanine in the rat. Stereochemical aspects.

The metabolism of (+)-cicletanine and (-)-cicletanine (10 mg kg-1) was studied in healthy male Wistar rats 24 hr after a single dose and following daily oral administration for 25 days. Urine, collected in 24-hr intervals on days 1, 5, 10, 15, 20, and 25, was analyzed by an HPLC method for parent drug and its sulfate/glucuronide conjugates. In urine, the sulfate and glucuronide conjugates of cicletanine were the only two major components quantitated; parent drug was a minor component. Within 24 hr after the first dose of (+)-cicletanine, the sulfate conjugate was the major urinary component; the ratio of sulfate to glucuronide conjugate was 3. After oral administration of (-)-cicletanine, the glucuronide and sulfate conjugates were present in similar amounts. For each enantiomer, the ratio of sulfate/glucuronide did not change upon multiple dosing, and inversion of the enantiomers did not occur. Although sulfate and glucuronide conjugates of each enantiomer are formed, the relative amounts of each conjugate depends on the enantiomer, indicating that there is stereospecificity in the disposition of cicletanine.

Animals↗
PubMed1994

Coronary artery stenosis and occlusion: value of 99Tcm-MIBI SPECT.

The aim of this study was to evaluate and validate a new quantification method for 99Tcm-sestamibi single photon emission computed tomographic (SPECT) myocardial imaging based on a four-slice analysis method and to check the functional results of percutaneous transluminal coronary angioplasty (PTCA). Using the calculated pathological area of the scintigram as an index for myocardial ischaemia, the overall sensitivity was 81-90% and the overall specificity was 74-98%. Analysis of variance of the repeated measurements revealed good reproducibility (coefficient of variation 8.4%). A significant correlation was found between the size of the exercise-induced perfusion defects and the degree of coronary stenosis. The comparison of radionuclide ventriculography and the perfusion image in 27 patients revealed a good correlation between the resting global ejection fraction and myocardial perfusion, but there was no correlation during exercise, indicating a dissociation between myocardial perfusion and function during exercise conditions in patients with coronary artery disease (CAD). Patients with total coronary occlusions showed more resting defects than patients with partial stenoses. Both groups benefit from PTCA or re-opening of chronic coronary occlusion, respectively. Exercise-induced myocardial ischaemia significantly decreased, and in 36% of the patients with previous myocardial infarction a significant reduction of the size of the resting perfusion defects occurred. In conclusion, our quantification method is suitable for the accurate non-invasive diagnosis of CAD, and for the follow-up of the invasive treatment of coronary artery stenoses and occlusions.

Adult↗
PubMed1994

Noninvasive methods in the early detection of restenosis after percutaneous transluminal angioplasty in peripheral arteries.

In a prospective study, several noninvasive methods were evaluated in the early detection of restenosis after percutaneous transluminal angioplasty in peripheral arteries. Sensitivity and specificity of various noninvasive resting and exercise methods for the detection of restenosis were determined. It is concluded that noninvasive follow-up after percutaneous transluminal angioplasty in peripheral arteries requires exercise testing with determination of ankle-arm index or segmental arterial pulse oscillography for the early detection of restenosis.

Aged↗
PubMed1994

Reopening of chronic coronary occlusions by low-speed rotational angioplasty.

Total occlusions are found in 10% to 20% of patients undergoing coronary angioplasty. The low-speed rotational angioplasty system (ROTACS) was developed as an addition to conventional guidewire techniques in chronic occlusions. It can be employed if the passage of the obstructed vascular segment with a conventional guidewire fails. The results in 200 patients presented here indicate that angioplasty expands the option of nonsurgical coronary revascularization.

Angioplasty↗
PubMed1994

Discordance of anti-ischemic and hemodynamic effects of captopril in stable coronary artery disease.

BACKGROUND: The role of angiotensin converting enzyme (ACE) inhibition in patients with coronary artery disease without concomitant disease such as heart failure or hypertension has not been elucidated. In this double-blind, cross-over, randomized trial of the ACE inhibitor captopril, its antianginal and anti-ischemic effects were studied during monotherapy and in the presence of an organic nitrate. METHODS: Thirty-seven patients (34 men, three women) with stable coronary artery disease and exercise-induced ST-segment depression were enrolled. After a washout phase without medication they received placebo, isosorbide dinitrate (ISDN) 20 mg twice daily, captopril 12.5 mg twice daily, and the combination of both for 1 week each, after which exercise tolerance, blood pressure and heart rate (supine, standing and 24 h profile), and peripheral arterial vasodilatation (finger pulse plethysmography) were assessed. RESULTS: Thirty-three patients completed all phases of the study. Exercise-induced anginal symptoms occurred in 17 patients, and asymptomatic ischemia was seen in the other 16 men. In comparison with ISDN, the anti-ischemic effects of captopril were minimal, despite a similar reduction in blood pressure. Compared with baseline, 1 week of placebo reduced the sum of ST-segment depression, the main efficacy parameter, by 10% (NS), captopril by 19% (NS), ISDN by 37% (P < 0.001) and the combination of captopril and ISDN by 42% (P < 0.001; NS versus ISDN). No patient remained completely free of exercise-induced angina during treatment with captopril; however, three patients after ISDN and seven patients after the combination did (P < 0.05). Blood pressure at rest decreased at peak effect by 9-10% systolic (P < 0.001) with monotherapy and by up to 7% diastolic (P < 0.001), and during combined therapy with captopril and ISDN by 18% systolic (P < 0.001) and 12% diastolic (P < 0.001). Significantly enhanced circulatory effects of captopril plus ISDN versus ISDN were found for blood pressure (P < 0.001) and peripheral arterial vasodilation (P < 0.01). The reflex tachycardia induced by ISDN in the upright position (5 beats/min) was not blocked by captopril during combined therapy. CONCLUSIONS: The antianginal and anti-ischemic effects of captopril alone were marginal, despite significant circulatory effects after short-term administration. Although captopril in combination with ISDN resulted in a significant further blood-pressure-lowering effect and increased peripheral arterial vasodilatation, the magnitude of potentiation of the anti-ischemic nitrate effects was, in contrast, small. Only exercise-induced angina was further improved by the use of the combination. No paradoxical worsening of ischemia or angina was seen after captopril. Thus, although captopril has no place as first-line therapy for ischemia, its use in combination with ISDN could be advantageous for long-term prognosis.

Aged↗
PubMed1994

[Reopening of chronic coronary occlusions--initial references for prognostic indications].

Today indication for percutaneous transluminal coronary angioplasty is based on typical chest pain and objective signs of myocardial ischemia during exercise. Especially in chronic coronary occlusions, however, prognostic implications may play an increasing role in the future. The case report describes long-term follow-up of a patient in whom a chronic complete occlusion of the right coronary artery could be reopened successfully back in September 1988. At this time, the peripheral part of the occluded RCA was filled retrogradely by septal collaterals from the LAD. After reopening the patient remained symptom-free for more than two years. In January 1991 again severe angina recurred and ECG showed a non-transmural anterior myocardial infarction. The LAD was occluded proximal and the peripheral part was filled retrogradely by septal collaterals coming from the right coronary artery which was still open (flow reversal). Left ventricular function was only slightly impaired and the LAD occlusion could be reopened successfully too. The case suggests that prognostic implications should be taken into consideration in addition to symptoms especially in complete coronary occlusions.

Aged↗
PubMed1994

UVAL-MED a universal visual associative language for medicine.

We describe UVAL-MED, a Universal visual associative language for medicine, and propose its use in combination with diagnostic reasoning and decision support systems. When fully developed, our system will automatically translate SNOMED terms to UVAL-MED terms. Grammar and syntax for UVAL-MED are defined and its features as a language-independent tool are discussed. The perceived advantages of our graphical language for rapid integration of knowledge and the assessment of developing situations could thus facilitate decision making.

Computer Graphics↗
PubMed1993

Somatic pain threshold and reactive hyperemia in autonomic diabetic neuropathy and silent myocardial ischemia.

In 31 patients with coronary artery disease (autonomic neuropathy, n = 11; diabetes without neuropathy, n = 10; silent myocardial ischemia without diabetes, n = 10) difference in somatic pain threshold and plethysmographically determined reactive hyperemia induced by forearm skeletal muscle ischemia was investigated. There was no difference in reactive hyperemia after passive maximum forearm ischemia in the three groups indicating identical vascular reactivity. After symptom-limited ischemic work however, reactive hyperemia was significantly higher in patients with silent myocardial ischemia as compared to diabetic patients. Exercise time was longer in patients with silent myocardial ischemia (153 +/- 51 s) as 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 (9/10). In conclusion, patients with silent myocardial ischemia have a higher ischemic tolerance in the working forearm as compared to diabetic patients with and without neuropathy. There is a quantitative difference in ischemic tolerance between patients with silent myocardial ischemia and patients with diabetic neuropathy.

Autonomic Nervous System Diseases↗
PubMed1993

[The effect of intracoronary infused captopril on luminal width in coronary stenosis].

To elucidate the mechanism of anti-ischaemic and anti-anginal action of angiotensin-converting-enzyme inhibitors, a randomized double-blind study was undertaken in 30 consecutive patients (27 men, 3 women; mean age 58 [28-70] years) with stable angina and at least 50%, angiographically well demonstrated, stenosis of one of the main coronary artery branches. They received an intracoronary infusion of either 0.5 mg captopril (n = 16) or of a placebo (n = 14) to see whether in this form of application the drug could cause an acute dilatation of a coronary stenosis. The diameter before captopril administration was 1.40 +/- 0.63 mm, while 1, 5 and 10 min after infusion it was 1.49 +/- 0.58 mm, 1.30 +/- 0.54 mm and 1.41 +/- 0.59 mm (not significant). There was also no significant difference between captopril and the placebo. The absence of effect with captopril may be due to insufficient liberation of endothelium-derived relaxing factor in an arteriosclerotic coronary segment.

Adult↗
PubMed1993

Immediate sealing of arterial puncture sites after cardiac catheterization and coronary angioplasty using a biodegradable collagen plug: results of an international registry.

OBJECTIVES: The aim of this study was to evaluate the safety and efficacy of a biodegradable collagen plug that has been developed to reduce the arterial compression time required to achieve hemostasis at the arterial puncture site after diagnostic and interventional coronary procedures. BACKGROUND: After diagnostic and interventional coronary catheterization procedures, local arterial compression is required to achieve hemostasis and complications may ensue, especially in patients on full anticoagulation. METHODS: Between March 1991 and July 1991, 252 patients admitted for routine coronary angiography or angioplasty to four large hospitals received such a hemostatic device immediately after the procedure. Hemostasis was achieved with collagen in 87% of patients after a mean compression time of 4.8 min. Time to hemostasis was independent of the heparin load. A total of 54 hematomas (21%) was reported; all but 2 resolved without additional treatment. Two patients had a severe hematoma, requiring blood transfusion, and two patients required surgery to repair a pseudoaneurysm. During a follow-up period of 4 weeks no severe late complications were reported. CONCLUSIONS: We conclude that the collagen plug appears to be a safe device to achieve hemostasis at the arterial puncture site, independent of anticoagulation.

Adult↗
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

Procedural results and patient selection in recanalization of chronic coronary occlusions by low speed rotational angioplasty.

From 1988 to 1991, 200 consecutive patients (18 female, 182 male, mean age 55.4 +/- 9 years) with chronic coronary occlusions resistant to recanalization by conventional techniques were treated by low speed rotational angioplasty. Indication was based on preserved left ventricular contraction and on exercise-induced symptoms or exercise induced signs of myocardial ischaemia. Duration of occlusion ranged from 1 to 192 months (median 6 months, interquartile range 4-9 months, mean 12 +/- 26 months). Success rate was 91% in occlusions 4 weeks-3 months old, 72% in occlusions 4-6 months old, 55% in occlusions 6-12 months old and 8% in occlusions older than 12 months. In 99 of 116 successfully treated patients (85%) follow-up angiography was performed 4 months after recanalization. In 80/99 (81%) patients the vessel remained open. Fifty of these 80 patients needed no further intervention, while 30/80 of the patients had restenosis treated by a second PTCA in 28 patients. Nineteen of the 99 (19%) patients had reocclusions. Including cases submitted to a second dilation, and angiographically determined long-term patency 4 months after successful recanalization was thus achieved in 78/99 (78%) of patients. Minor complications included asymptomatic dissection in the recanalized vascular region. Serious complications occurred in two proximal occlusions of the left anterior descending coronary artery dissecting into the adjacent circumflex branch, and embolism into distal parts of recanalized vessels. It is concluded that in selected patients low speed rotational angioplasty (Rotacs) is a safe technique applicable to chronic total coronary occlusions even if the duration of occlusion exceeds 6 months and after conventional techniques have failed.(ABSTRACT TRUNCATED AT 250 WORDS)

Atherectomy, Coronary↗
PubMed1993

Effects of nitrendipine and lisinopril on blood pressure and sodium excretion in ciclosporin-associated hypertension after heart transplantation.

Hypertension associated with ciclosporin A may be mediated by sodium and volume retention. Therefore, the effects of an antihypertensive therapy (6 weeks) with nitrendipine (10-20 mg twice daily) or lisinopril (10-20 mg once daily) on office blood pressure, 24-hour ambulatory blood pressure, and left ventricular function were evaluated in a randomised, double-blind cross-over trial in patients after heart transplantation. Nitrendipine and lisinopril were equally effective in lowering office and ambulatory systolic and diastolic blood pressures. After an acute sodium load (210 mval/2 h i.v.), sodium excretion was significantly increased during therapy with lisinopril but only slightly during nitrendipine, indicating that angiotensin-converting enzyme inhibition may improve the sodium-retaining state of heart transplant recipients associated with ciclosporin A.

Adult↗