Biomedical subjects

B Frenking

Publications and source records attributed to B Frenking.

8 recordsLinked to original sources

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

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

Electrophysiologic effects of asocainol, a new antiarrhythmic agent with predominant class I action.

In experiments on 6 mongrel dogs the electrophysiologic effects of the new antiarrhythmic compound (+/-)-6,7,8,9-tetrahydro-2,12-dimethoxy-7-methyl-6-phenethyl-5H- dibenz[d,f]azonin-1-ol (asocainol) were examined in the non-ischemic heart. The PR interval increased significantly following doses of 5 mg/kg caused by a conduction delay in the His-Purkinje system. At high doses (10 mg/kg) the QRS duration was also prolonged. Atrial and ventricular effective refractory periods were only slightly increased. Asocainol significantly increased the atrial fibrillation threshold, whereas the ventricular fibrillation threshold was not altered. Hemodynamics were not changed except for a slight increase in heart rate after 10 mg/kg asocainol. Thus asocainol predominantly exhibited class Ia antiarrhythmic properties, whereas calcium antagonistic actions could not be established in this intact dog heart model.

Animals↗

PubMed1987

[Treatment of chronic ventricular arrhythmias with the new class Ic anti-arrhythmia agent diprafenon--results of long-term therapy].

Diprafenone is a new antiarrhythmic drug with a dominant local anaesthetic action and an additional beta-sympathicolytic activity. In this study, the results of long-term treatment (8 months on average) obtained from 27 patients with chronic ventricular arrhythmias are reported. Before diprafenone, all patients were treated unsuccessfully with flecainide, propafenone, sotalol, combined sotalol/flecainide and sotalol/propafenone, and another two to six antiarrhythmic agents. Following diprafenone (300-600 mg/24 h), a substantial reduction in arrhythmic activity (greater than or equal to 80%; Lown classification less than or equal to II) was achieved in 21 cases. In 12 patients, side effects (fatigue, headache, blurred vision, dizziness and heartburn) were apparent. Diprafenone had to be discontinued in five patients, because of these side effects. At dosages greater than or equal to 450 mg/24 h, the PQ interval was significantly lengthened, and QRS duration prolonged. In one patient, an AV block III degree developed. In another case, SGOT and SGPT increased significantly; this increase was reversed after the drug was discontinued. Despite these side effects, further clinical evaluation of the compound seems promising, as the antiarrhythmic potency of diprafenone is very strong and superior to that of propafenone with respect to the required doses.

Adult↗

PubMed1986

[Dynamic 2-chamber overdrive stimulation with an implantable pacemaker system as a method for terminating slow ventricular tachycardias].

A case report is given on a new method for treatment of drug-resistant slow ventricular tachycardias by automatic dynamic overdrive stimulation, using an implantable pacemaker system. In a 60-year-old patient with coronary heart disease and ventricular tachycardia refractory to drug therapy, an antitachycardia Medtronic pacemaker (type SP 0501) was implanted in October 1984 and used successfully in 65 attacks during 13 months. However, when trying to terminate the tachycardia by means of programmed stimulation, acceleration of the ectopic ventricular rate occurred at 8 occasions. The administration of the experimental antiarrhythmic drug diprafenone (Class Ic) resulted in a reduction of the ventricular frequency but not of the rate of attacks. Then the Vitatron Quintech DDD pacemaker was implanted, providing the chance of terminating the now reduced ventricular rate by the dynamic overdrive mode.

Cardiac Complexes, Premature↗

PubMed1986

Effects of the new vagolytic compound ciclotropium bromide on heart rate and atrial vulnerability.

The effects of the new vagolytic compound alpha-phenylcyclopentane-acetic acid-N-isopropyl-nortropine ester methobromide (ciclotropium bromide) on heart rate and atrial vulnerability were assessed in the animal experiment. Therefore, the comparative effects of atropine (A) and ciclotropium bromide (C) on heart rate (HR) and electrical stimulation thresholds for repetitive atrial extrasystoles (RET) and fibrillation (AFT) were established in 14 mongrel dogs (BW 20-30 kg, artificial ventilation, piritramide-N2O anaesthesia). AFT and RET were determined using trains of rectangular current pulses (13 single pulses, 2 ms, 200 Hz) applied to the right atrial endocardium via bipolar platinum electrodes during the vulnerable period of atrial excitation, which was determined by scanning of the relative refractory period in steps of 10 ms. A (0.025 mg/kg) caused a small transient increase in the AFT; HR rose from 82 +/- 7 to 138 +/- 10/min. Control values were regained after 30 min. RET did not show any significant change. C (0.25 mg/kg) effected a significant increase in the AFT from 7.7 +/- 2 to 34 +/- 6 mA and in HR from 93 +/- 5 to 148 +/- 6/min. The effects lasted about 2 h. RET was not altered.

Animals↗

PubMed1986

[Method for the direct comparison of the frequency behavior in QT- and activity-controlled pacemaker systems].

A non-invasive method of testing the suitability of an activity-controlled pacemaker system in patients with VVT-programmable systems is presented. The QT-time controlled TX-pacemaker of a 36-year-old patient was programmed into the VVT-mode. Then the activity-controlled pacemaker (Activitrax) was fixed epicutaneously above the pectoral muscles and two stimulation electrodes were applied above the implanted pacer and the tip of the implanted probe. Thus the external could be made to trigger the implanted system. The frequency profile was recorded with identical loads with QT and/or activity control. For both the frequency-adapted pacemaker systems, the direct comparison yields characteristic frequency profiles: a quick frequency increase and decrease of both Activitrax and load, but a delayed frequency profile of the QT-controlled pacer. Different frequency maxima are rendered by the two pacemakers as a function of the load.

Adult↗

PubMed1985

Assessment of the antiarrhythmic profile of the new class I agent diprafenone.

The antiarrhythmic profile of the new compound diprafenone was evaluated using various dog models relevant to conditions in humans. In 8 animals, dose related effects on intracardiac conduction, atrial and ventricular refractoriness, fibrillation thresholds and on hemodynamics were determined. In this part of the study also the comparative actions of propafenone were assessed (8 animals). IN another 28 dogs the antiarrhythmic and antifibrillatory actions of diprafenone following short-term coronary occlusion and subsequent release were established. In additional 16 animals the effects of diprafenone on "delayed" reperfusion arrhythmias following release of coronary artery occlusion after 2 h and on stimulus-induced ventricular tachycardia in acute myocardial infarction were investigated. The results show: Diprafenone slows conduction through all parts of the AV-conduction system. The AH-interval is significantly prolonged, QRS-duration and ventricular repolarization are slightly lengthened, and both the atrial and ventricular refractory periods and fibrillation thresholds are markedly increased. Heart rate is slowed, aortic pressure and cardiac output are not significantly changed. Following acute short-term coronary artery occlusion, the incidence of ventricular fibrillation is reduced, and the drop in the ventricular fibrillation threshold is diminished. By contrast, the frequency of ventricular fibrillation after release of short-term occlusion is not influenced. "Delayed" reperfusion arrhythmias, however, are completely abolished, and initiation of ventricular tachycardia in myocardial infarction can be easily prevented. With a predominant local anesthetic mechanism of action and a potential additional beta-sympatholytic activity, the new compound displays close similarities to propafenone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗