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Biomedical subjects

H Kreuzer

Publications and source records attributed to H Kreuzer.

At least 253 records · Page 14Linked to original sources
PubMed1984

Temporal and spatial development of myocardial infarcts in porcine hearts without significant collateral blood flow.

To evaluate the time-dependent beneficial effect of reperfusion on infarct size, we investigated the temporal and spatial development of infarcts in porcine hearts. The left anterior descending coronary artery was occluded in 17 pigs for different periods of time. Ischemia was always followed by 4 hours of reperfusion. After 60 minutes of ischemia, transmural needle biopsies subdivided into subendocardial and subepicardial halves were removed from the ischemic apex to determine the tissue concentrations of adenosine triphosphate and nicotinamide adenine dinucleotide. The myocardium at risk was determined with a fluorescent dye, and the infarcted tissue with nitroblue tetrazolium stain. Infarct size was expressed as the ratio of the infarcted myocardium over the risk region. Ischemic cell death began in the jeopardized left ventricular subendocardial septum after about 30 minutes of ischemia. Further progress involved the right subendocardial septum and the subendocardium of the left anterior free wall. After 75 minutes of ischemia, most of the myocytes were already irreversibly injured. Tissue damage from the infarctions was complete after 90 to 120 minutes of ischemia. These results indicate that in hearts without a significant collateral blood flow, reperfusion can only reduce infarct size if initiated within 60 to 75 minutes of ischemia. As in canine hearts, infarctions in porcine hearts progress from the ischemic subendocardium toward the outer layers.

Journal Article↗
PubMed1984

Effect of nisoldipine on electrophysiological parameters in patients pretreated with beta-blockers.

The effect of the new 1,4-dihydropyridine calcium antagonist nisoldipine on electrophysiological parameters was investigated in 10 patients who were pretreated with a beta-blocker. 9 patients received atenolol (75 mg/d) and 1 patient pindolol (15 mg/d) at least for three days prior to the electro-physiological study. Before and after the intravenous injection of nisoldipine (1.5 micrograms/kg body weight) the sinus node function (spontaneous sinus node cycle length, sinus node recovery time, rate corrected sinus node recovery time), the conduction times from the high right atrium to the apex of the right ventricle, and the refractoriness of the different compartments of the heart were assessed. Arterial blood pressure was measured with the cuff method. Nisoldipine induced a slight but significant increase of the heart rate without effecting the blood pressure significantly. All other measured electrophysiological parameters remained unaltered, especially the conduction time of the av node. It is concluded that concerning electrophysiology nisoldipine can safely be combined with beta-blockers because this calcium antagonist does not exert an electrophysiological effect.

Adrenergic beta-Antagonists↗
PubMed1984

[Primary angiosarcoma of the heart--3 case reports and a review of the literature].

Three cases of primary angiosarcoma of the heart diagnosed intra vitam are reported. A review of the literature with 118 described cases is given, with special reference to localization, clinical symptoms, diagnostic procedures, and prognosis. Modern diagnostic procedures make it possible to diagnose cardiac tumors in the living patient, but prognosis remains poor.

Adult↗
PubMed1984

Usefulness and limitations of invasive diagnostic procedures in assessment and quantification of valvular lesions.

With increasing number of noninvasive techniques in clinical cardiology, the question emerges whether it is still justified to continue with cardiac catheterization in the assessment of valvular lesions on a routine basis. Therefore, advantages and disadvantages of invasive and noninvasive procedures are compared with respect to the information they provide in patients with valvular heart disease. Usefulness of invasive criteria in the assessment and quantification of valvular lesions have been analyzed. Limitations of these invasive criteria are derived from a score relating the accuracy obtained to the methodical expense incurred with a given diagnostic parameter. From these analyses and in consideration of findings in the literature, we conclude that cardiac catheterization is not only justified but necessary, particularly in patients prior to valve surgery in order to quantitate the valvular lesion, differentiate between valvular and myocardial dysfunction and screen for associated abnormalities such as concomitant coronary artery disease. Despite the progress in recent years, noninvasive techniques cannot provide this combination of precise information.

Aortic Valve Insufficiency↗
PubMed1984

[Occlusion of the right coronary artery with acute right heart infarct and cardiogenic shock].

In a 42-year-old patient with an acute inferior infarction the right coronary artery was recanalised by intracoronary streptokinase 4 hours after the onset of symptoms. In spite of early reperfusion the patient developed an extensive myocardial infarction and died three days later from cardiogenic shock. Autopsy revealed an almost complete necrosis of the right ventricle including the inferior interventricular septum and the adjacent left ventricular wall. Diagnostic and therapeutic problems in the so-called dominant right ventricular infarction are discussed.

Adult↗
PubMed1984

[Significance of the detection of echocardiographic vegetation for the clinical course and prognosis of infectious endocarditis].

52 patients with infective endocarditis and manifestations on 62 valves were examined by echocardiography between January 1978 and May 1983. In 34 patients (65%) vegetations were visible at least on one valve, in 10 patients (19%) the result was doubtful and in 8 patients (16%) no vegetations could be seen. In a comparison of echocardiographic and intraoperative or autopsy findings, with doubtful results left out, the over-all sensitivity was 96%, specifity 44% and reliability 83%. There was no statistically significant difference in echocardiographic results between patients who were operated upon or treated medically. Patients with positive echocardiographic vegetations had no statistically significant higher risk of embolism. Morphological aspects of the vegetations had no influence on clinical course and prognosis either. All 12 patients (23%) who died had positive echocardiographic vegetations. Yet the difference from the surviving group was not significant. Hence, echocardiography is a sufficiently sensitive and reliable method for the detection of vegetations in patients with infective endocarditis. However, echocardiographic findings alone are of no consequence in medical or surgical treatment, arterial embolization or prognosis.

Adolescent↗
PubMed1984

[Slow flow in the coronary system and ST elevation in the ECG in left atrium catheterization].

A complication of transseptal left atrial catheterization is a transient ST-elevation in the ECG with unknown cause. In this case simultaneous angiography showed a so-called "slow flow" of dye dilution in the coronary artery. A coronary spasm or an embolic occlusion of the coronary artery could be excluded. The reason for this phenomenon might be a reflex increase of the arteriolar resistance with transient ischemia.

Aged↗
PubMed1984

[Cardiomyopathy in female carriers of the Duchenne gene].

The present report describes a family with X-linked recessive muscular dystrophy. In two female carriers a myocardial involvement could be demonstrated, which dominated the clinical picture in one patient. Obviously a congestive cardiomyopathy may develop in female carriers of X-linked recessive muscular dystrophy of the Duchenne-type.

Adolescent↗
PubMed1983

High dose intravenous streptokinase in acute myocardial infarction.

Early recanalization of infarct-related coronary arteries has been attempted in 40 patients with acute myocardial infarction (AMI) and angiographically proven total occlusion by brief high dose intravenous streptokinase infusion (IVSK). In 24 patients (60%) recanalization was achieved after 48 +/- 14 min of IVSK at an infusion rate of 30,000 to 40,000 IU/min (group A), in 16 patients there was a late (greater than 2 h) or no recanalization (group B). The total dose of SK was 1.7 +/- 0.48 Mio IU in group A and 1.74 +/- 0.41 Mio IU in group B, the time from the onset of symptoms to peak myocardial enzyme of creatine phosphokinase (CKMB) 11 +/- 3 h in group A and 22 +/- 6 h in group B (p less than 0.001). Biplane left ventricular ejection fraction increased from 55 +/- 9% at the time of acute angiography to 58 +/- 10% after 14 to 24 days in group A (p less than 0.1) and decreased from 49 +/- 11 to 41 +/- 11% in group B (p less than 0.005). There were four reocclusions in group A, two could be reopened by i.v. urokinase (1 Mio IU over 30 min). During a follow-up period of 18 +/- 8 months one patient in group A died from an early ventricular rupture 2 hours after recanalization, and one patient in group B from heart failure 7 months after IVSK. There was no serious bleeding or other complication related to IVSK. We conclude that IVSK is an effective and safe means of early recanalization of coronary thrombosis in AMI, and feasible in the majority of patients with AMI.

Adult↗
PubMed1983

Endoanaesthesia of left ventricular mechanoreceptors by steady state infusion of lignocaine and the influence of dopamine.

We recorded the afferent activity of 11 left ventricular mechanoreceptors in filaments of the vagus nerve in 10 chloralose-anaesthetised cats. The fibres showed low irregular spontaneous activity of 2.9 (0.2 to 8.4) spikes X s-1. During temporary occlusion of the left anterior descending or left main coronary artery they were activated to 19.1 (4.8 to 47.0) spikes X s-1. Intravenous infusion of 0.175 and 0.35 mg X kg-1 X min-1 lignocaine lowered heart rate and blood pressure. The spontaneous nerve fibre activity remained unchanged by the local anaesthetic, whereas the maximum activity evoked by coronary artery occlusion was reduced to 14.7 (2.6 to 34.1) and 10.9 (2.4 to 27.6) spikes X s-1. An additional infusion of 5 and 10 micrograms X kg-1 X min-1 dopamine during continued application of 0.35 mg X kg-1 X min lignocaine raised heart rate and blood pressure to control values but had only minimal effects on the response of the fibres to coronary occlusion. It is concluded that lignocaine exerts a specific endoanaesthetic effect on the left ventricular mechanoreceptors, which is not mediated by its negative inotropic side effect.

Animals↗
PubMed1983

The toxicology of brotizolam.

Acute studies. Following oral or intraperitoneal administration, toxicity was very low (LD50 in rodents greater than 10,000 and greater than 900 mg/kg, respectively). Subacute and chronic studies in rodents. Signs of toxicity were seen only at doses of 400 mg/kg or more. Histopathological changes were found only in the 78-week study. Subacute studies in dogs (intravenous) and primates (oral). In dogs, doses of 0.1 and 0.3 mg/kg produced ataxia, salivation, and diarrhoea. In monkeys doses of 7 mg/kg or higher produced ataxia, increased appetite, hyperreflexive muscular spasms, increase in liver weight, and lipid depletion of the adrenal cortex. Reproductive studies in the rat and rabbit. Repeated doses of up to 30 mg/kg were not associated with any disturbance in fertility; nor were any embryotoxic or teratogenic effects observed. When dams wer treated with 400 mg/kg, litter mortality was markedly increased. Mutagenicity studies. The four different tests performed gave no indication of any mutagenic effect. Local tolerance tests in the rabbit. Brotizolam was well tolerated when administered intramuscularly, intra-arterially, or intravenously. Carcinogenicity studies in rodents. The mouse study showed no evidence of a tumourigenic effect. The rat study is still being evaluated. The toxicological studies demonstrate that brotizolam has an unusually wide therapeutic range. Findings of toxicological significance, most of which were reversible, were first recorded at doses of 7-10 mg/kg, i.e. at more than 100-times the intended human therapeutic dose.

Adrenal Glands↗
PubMed1983

Nitrates in aortic valve disease: acute and chronic effects.

The beneficial effect of Nitroglycerin (NTG) on myocardial oxygen-supply-demand ratio in severe aortic stenosis has been already demonstrated. But the chronic administration of isosorbide dinitrate (ISDN) does not reduce the increase in left ventricular filling pressures during exercise. Therefore in severe aortic stenosis, the effects of chronic nitrate administration on left ventricular hemodynamics during exercise do not correspond to the beneficial acute effects of NTG. In aortic insufficiency, sublingual NTG has only minor effects on left ventricular volumes, heart rate and cardiac output. A moderate reduction in pressures results in a significant reduction of wall stress, while there is no major change in regurgitant fraction.

Aortic Valve Insufficiency↗
PubMed1983

Comparative hemodynamic study of IS-5-MN and ISDN in man--which are equieffective doses?

In a crossover study, the hemodynamic effects of 40 mg sustained release isosorbide dinitrate were compared with those of 40 mg isosorbide-5-mononitrate in 10 patients after myocardial infarction. No differences between both drugs were seen in the magnitude of their effects on cardiac preload. The onset of the effect, however, was faster after IS-5-MN and reached its nadir earlier than after sustained release ISDN. Thus, both drugs are hemodynamically equieffective in equal doses, but their effects show different time courses.

Adult↗
PubMed1983

Development of tolerance during nitrate therapy: dissociation of arterial and venous effects. A doppler echocardiographic study.

Using pulsed Doppler echocardiography as a noninvasive method to assess central venous return, nine healthy volunteers were studied before and after isosorbide dinitrate given four times daily for 8 days. First dose isosorbide dinitrate led to a drop in heart rate and mean arterial pressure, and right ventricular inflow velocities decreased. With sustained treatment effects on systemic venous return remained unaltered, whereas reduction in heart rate and in mean arterial pressure was lost. Regarding this disappearing response as indicating a form of tolerance, venous hemodynamic nitrate effects were unaltered by development of tolerance on the arterial side.

Adult↗
PubMed1983

[Prognostic value of thallium scintigraphy in diagnostic problem cases].

Quantitative myocardial scintigraphy was performed in 40 patients with a medium prevalence of coronary artery disease (CAD), i.e. in cases with diagnostic difficulties. The results were compared with those of coronary angiography and ventriculography performed within 6 months thereafter. Sensitivity of scintigraphy in 16 patients with CAD was 88% and specificity in 14 individuals without heart disease was 93%. But in 10 patients with non-coronary heart disease specificity decreased to 30%. Scintigraphic evidence of ischemia increased specificity to nearly 100% including patients with non-coronary heart disease but sensitivity was reduced to 69%. The results demonstrate that myocardial scintigraphy with 201Tl is useful in cases with suspected CAD if diagnostic difficulties arise during the early phase of investigation. But there are limitations due to a rather high prevalence of non-coronary heart disease in such groups.

Adult↗