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Biomedical subjects

H Heuer

Publications and source records attributed to H Heuer.

At least 91 records · Page 5Linked to original sources
PubMed1988

Inhibitory effect of oral WEB 2086, a novel selective PAF-acether antagonist, on ex vivo platelet aggregation.

WEB 2086 is a novel PAF-acether antagonist, whose pharmacological action in man has only been preliminarily defined. Twelve healthy male volunteers received oral doses of 5, 30 and 90 mg and over the following 24 h inhibition of 5 x 10(-8) M PAF-acether-induced platelet aggregation ex vivo was studied as an indicator of pharmacological activity. WEB 2086 inhibited PAF-acether-induced platelet aggregation in all the doses tested, with the maximum effect 1 to 2 h after administration. After 2 h 5- 30- and 90-mg doses caused, respectively, 87, 98 and 100% inhibition. The magnitude and duration of the inhibitory effect was dose-dependent, with a significant action still detectable 10 h after administration of all three doses, and 12 h after administration of the two highest doses (30 and 90 mg). The subjects did not complain of any significant adverse effect and all completed the study.

Adult↗
PubMed1988

The effects of sustained vertical gaze deviation on the resting state of the vergence system.

Vergence of the eyes in the dark depends on the vertical direction of gaze. In three experiments this phenomenon was studied using eye inclinations and head tilts of 5 min duration during which monocular or binocular near and distant stimuli were inspected. The effects of eye inclination and head tilt on dark vergence were temporally stable; they exhibited even a tendency to increase with the passage of time. On return to horizontal gaze, positive aftereffects were found, that is dark vergence was biased towards its value with a vertically deviated gaze. The effect of vertical gaze direction turned out to be additive to the effect of binocular near fixation. These findings represent evidence against the hypothesis that the effect of vertical gaze direction on dark vergence is mediated by a feedforward signal that is related to voluntary effort in raising or depressing the eyes.

Adaptation, Ocular↗
PubMed1988

Clinical experience with the rate responsive pacemaker Sensolog 703.

Pacemaker therapy with rate responsive systems becomes increasingly more important. Numerous clinical and experimental trials have been conducted thus far to investigate different sensors of metabolic demands of the body, functioning independently of an atrial electrogram. To transform mechanical energy into electrical energy, activity-triggered systems utilize a piezo-quartz as their sensor. Thirty five patients suffering from pathological bradyarrhythmias and therefore from an inadequate increase of the heart rate during exercise were supplied with a Sensolog 703. Clinical follow-up was first performed with the help of treadmill ergometry, later on by walking on flat ground and climbing steps. The settings due to the first test caused inadequately high stimulation rates. A 24-h-Holter-ECG was necessary to control the programming and the rate profile in the patient's daily life. Using only the histogram and the rateread function, all rate adaptive parameters of the Sensolog 703 could be set by walking on flat ground and climbing steps. We defined a frequency of 75-85 min-1 to be appropriate during walking, respectively "low work." Individual programming ranged from 2-5/8-15/high-low/very fast-medium/fast-medium (slope, threshold, gain, reaction and recovery time). Reprogramming based on 24-h-Holter ECG was only necessary if the pacemaker was formerly adjusted with the help of treadmill ergometry. Besides, we observed an increase of the stimulation rate due to vibrations not related to exercise, e.g., by driving in a car.

Aged↗
PubMed1988

Termination of malignant ventricular tachycardias by use of an automatical defibrillator (AICD) in combination with an antitachycardial pacemaker.

We implanted an "Automatic Implantable Converter-Defibrillator" (AICD) and as far as useful an antitachycardial pacemaker (Intertach) in addition in 11 patients suffering from malignant ventricular tachycardias via a median sternotomy. In eight cases a coronary artery disease and in three cases a dilatative myopathy was the intrinsic disease. During surgery in all patients we attempted to trigger ventricular tachycardias and their termination by programmed stimulation. This procedure was successful in nine patients who received an antitachycardial pacemaker system. After the wounds healing, repeated induced ventricular tachycardias in all patients, who received a combination of the systems, could be terminated by the antitachycardial pacemaker prior to an intervention of the implanted defibrillator.

Cardiac Pacing, Artificial↗
PubMed1988

[Experimental and initial clinical experiences with the new class Ib anti-arrhythmia agent barucainide].

Barucainide is a new class Ib-antiarrhythmic compound which causes a reduction of the upstroke velocity and shortens the duration of the action potential in a dose-dependent fashion. The electrophysiological, hemodynamic and antiarrhythmic effects of the new drug were analyzed in experimental and clinical investigations. The results show that barucainide, in a dose range varying between 0.125-4.0 mg/kg i.v. fails to exert any significant effect on cardiac conduction and refractory times, heart rate, arterial blood pressure, cardiac output and left ventricular contractility. In a standardized animal model of ventricular arrhythmia, barucainide proved to be superior to lidocaine with respect to its antiarrhythmic potency. In a group of patients displaying chronic, otherwise therapy-resistant ventricular arrhythmias, the drug was effective in the majority of cases. Tolerance was excellent over a maximum observation period of 18 months. According to our first experimental and clinical observations, further testing of barucainide appears promising. The drug may be of particular value for treatment of ventricular arrhythmias in cases with left ventricular dysfunction, heart failure and severe conduction disturbances.

Adult↗
PubMed1988

[Pneumopyopericardium--a rare complication following surgical correction of an "upside-down stomach"].

The follow-up period after surgery of an upside-down stomach in a 53-year-old patient was complicated by a pneumopyopericardium due to Candida albicans and Enterococcus. Therapy was performed by pericardial drainage. Local instillations of Mezlocillin (100 mg/l) and Amphotericin B (1 mg/l, Candida-MIC = 0.1 mg/l), over a period of 10 days and followed by a systemic antimycosis with 5-Flucytosin (0.14 g/d/kg over 5 days) and Amphotericin B (0.3 mg/d/kg over 11 days) led to recovery. Six months after discharge from the hospital, echocardiography revealed only a thickened pericardium without hemodynamic disorders.

Candidiasis↗
PubMed1988

[Uni- and bipolar 2-chamber stimulation with a DDD system of programmable polarity].

In order to compare bi- (b) and unipolar (u) stimulation, sensing and electrical interference, twelve patients were followed over a period of ten months. The implanted device was the CPI Delta 925, programmable to the bi- and unipolar mode in the atrium (a) as well as in the ventricle (v). A CPI-4266 screw-in lead positioned in the atrium and a CPI-4260 hook lead placed in the ventricle were connected to the pacemaker. Intraoperatively determined were: (1) the threshold at pulse durations of 0.1 ms, of 0.5 ms and of 1.0 ms, (2) the P/QRS-amplitude, (3) the slew-rate and (4) the resistance in both the bi- and unipolar mode. Having programmed the atrial sensitivity to 0.25 mV or to 0.75 mV and the ventricular sensitivity to 0.5 mV or to 1.5 mV, we postoperatively examined and compared in the two modes of polarity the threshold (2.2 V and 5 V), the P/QRS-amplitude and finally the electrical interference triggered with the help of chest wall stimulation. All measurements were performed one day, four weeks and four months after implantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effect of amrinone in acute severe cardiac failure.

5-Amino-(3,4'-bipyridine)-6(1H)-one (amrinone, WIN-40680, Wincoram) is a potent positive inotropic agent with vasodilator properties. Its positive inotropic effects are unaffected by propranolol and by pre-treatment with reserpine. The effect of intravenous amrinone was studied in 15 patients with acute severe cardiac failure (NYHA class IV) who had failed to respond adequately to treatment with cardiac glycosides, diuretics, vasodilators and catecholamines. Catecholamine dosage was held constant during the period of the study. This is the first report of standardised combination therapy with catecholamines and amrinone. Initially, a mean cumulative dose of 1.6 +/- 0.3 mg/kg of amrinone was administered during the 1st h. This was followed by a long-term infusion of 5-15 micrograms/kg.min. Hemodynamic parameters were monitored by invasive techniques for a minimum of 48 h. At the time of maximal effect, the cardiac index increased from 1.54 +/- 0.35 to 2.8 +/- 0.61 l/min.m2 (p less than 0.001), and the pulmonary arterial capillary pressure decreased from 31 +/- 7.1 to 23 +/- 7.6 mmHg (p less than 0.01). Heart rate and systemic mean arterial blood pressure showed no significant changes during treatment. These results indicate that amrinone may be effective in patients with acute severe cardiac failure refractory to catecholamines.

Acute Disease↗
PubMed1987

Apparent motion in depth resulting from changing size and changing vergence.

Two experiments are reported in which the effect of combining stimuli of changing size and changing vergence on the perception of motion in depth was examined. Changing size and changing vergence corresponded to in-phase or anti-phase sinusoidal motions of an outline circle, with different amplitudes. In-phase stimuli had approximately additive effects on the estimated peak-to-peak amplitude of apparent motion in depth. Anti-phase stimuli did not cancel each other; apparent motion was in-phase with one or the other stimulus. When apparent motion was in-phase with one stimulus, there was only a limited influence of the other stimulus. The results are discussed with regard to a model proposed by Regan and Beverley for the combination of changing size and changing disparity.

Adult↗
PubMed1987

Prophylaxis of exercise-induced ventricular arrhythmias by verapamil.

In this study prophylactic antiarrhythmic effects of verapamil on exercise-induced ventricular arrhythmias are evaluated. Investigations were carried out on a total of 22 patients. All patients showed frequent and/or complex ventricular arrhythmias during repeated exercise tests under control conditions. After two control exercise tests all patients were treated with verapamil 120 mg given every 8 hours orally over 4 days. On the 3rd and 4th day of treatment the exercise tests were repeated. Verapamil caused a significant reduction in the incidence and severity of exercise-induced ventricular arrhythmias in 13 out of 22 patients. In patients with exercise-induced ST-segment depression a prophylactic action could be demonstrated in 9 out of 10 cases. The antiarrhythmic effect was independent of changes in heart rate. A reduction in myocardial oxygen consumption and direct electrophysiological effects (suppression of the 'slow response' and/or an increase in the resting potential of the 'depressed fast response') can be considered, as well as a suppression of 'triggered activity' or a direct inhibition of adrenergic effects. Calcium antagonists (type verapamil) prove to be suitable drugs for the treatment of exercise-induced ventricular arrhythmias in patients with myocardial ischaemia.

Adult↗
PubMed1987

[Prevention of effort-induced ventricular arrhythmia using verapamil].

In this study prophylactic antiarrhythmic effects of verapamil on exercise-induced ventricular arrhythmias were evaluated in a total of 22 patients. All patients displayed frequent and/or complex ventricular arrhythmias during repeated exercise tests under control conditions. After two control exercise tests, all patients were treated with 120 mg verapamil given every 8 h orally for 4 days. On the 3rd and 4th day of treatment the exercise tests were repeated. The results were that verapamil caused a significant reduction in the incidence and severity of exercise-induced ventricular arrhythmias in 13 out of 22 patients. In patients with concomitant significant ST-segment depression, a prophylactic action could be demonstrated in nine out of ten cases. The antiarrhythmic effect was independent of changes in heart rate. In patients with myocardial ischaemia, a reduction in myocardial oxygen consumption and direct electrophysiological effects (suppression of the "slow response" and/or an increase in the resting potential of the "depressed fast response") can be discussed as mechanisms of action. Also, a suppression of "triggered activity" or a direct inhibition of adrenergic effects must be considered. According to our results and the literature, calcium antagonists (verapamil type) proved to be suitable drugs for the treatment of exercise-induced ventricular arrhythmias, particularly in patients with concomitant myocardial ischaemia.

Arrhythmias, Cardiac↗
PubMed1987

[Electrophysiologic and hemodynamic effects of the new anti-arrhythmia agent diprafenone].

Diprafenone is a new antiarrhythmic agent currently under clinical investigation, with close chemical similarity to propafenone. In this study, the electrophysiological and haemodynamic effects of the compound were investigated both in animals, by experiment, and in man. Diprafenone produces a dose-dependent prolongation of conduction in all parts of the conducting system. Lengthening of PQ-time is more pronounced than prolongation of QRS. The atrial and ventricular refractory periods are also significantly prolonged. There are no significant changes in the QT-time. Heart rate and aortic pressure are slightly decreased. The electrophysiological and haemodynamic profile of Diprafenone is similar to propafenone with respect to a dominant local anaesthetic activity and an additional beta-sympatholytic effect. However, with respect to the dose needed, the efficacy of the new drug appears to be significantly stronger. Diprafenone can be considered an effective antiarrhythmic drug for the treatment of supraventricular and ventricular tachyarrhythmias.

Animals↗