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Biomedical subjects

F Bender

Publications and source records attributed to F Bender.

At least 55 records · Page 3Linked to original sources
PubMed1983

Effects of flecainide on atrial and ventricular stimulation thresholds to repetitive extrasystoles and fibrillation and on "2nd Phase" ventricular arrhythmias in dogs.

Repetitive extrasystole and fibrillation thresholds were assessed by various methods of programmed atrial and ventricular stimulation using intracavitary bipolar electrode catheters and a microcomputer based 3-channel stimulator as previously described. "2nd Phase" ventricular arrhythmias were produced by ligation of the left descending coronary artery. 2,5-Bis-(2,2,2-trifluoroethoxy)-N-(2-piperidylmethyl)benzamide acetate (flecainide, R 818, Tambocor) caused a significant increase of the atrial and ventricular fibrillation thresholds. The antifibrillatory action was similar in atrial and ventricular tissues. "2nd Phase" ventricular arrhythmias were dose-dependently reduced or abolished completely. Similar doses were required to suppress spontaneous arrhythmic activity and to increase the fibrillation thresholds. Thus, flecainide proved to be a powerful antiarrhythmic agent with strong antifibrillatory properties in therapeutic doses. It may be a promising drug for the treatment of atrial and ventricular reentrant arrhythmias.

Animals↗
PubMed1983

Comparative study of stress reactions during oral surgery after pindolol and metoprolol.

The prophylactic effect of a single oral dose of 5 mg pindolol (P) or 100 mg metoprolol (M) on sympathetic and adrenergic stress reactions was investigated by a double blind study in 40 patients undergoing oral surgery. A reduction of systolic and diastolic blood pressure as well as heart rate was noted after both, P and M, as was the increase of these parameters during surgery. Adrenaline-, noradrenaline- and c-AMP-level were reduced after systematic beta-blockade by P only, not after M. The increased lipolysis and glycolysis during surgery were prevented by P only. The stimulation of the hypothalamic and adrenal stress reactions were not influenced by either P or M. The application of the systematic beta-blocker with ISA (P) only was suited to prevent the increase of catecholamine levels in plasma and peripheral receptor stimulation.

Adrenocorticotropic Hormone↗
PubMed1982

Beta-adrenoceptor blockade in stress due to oral surgery.

1 The effects of a single oral dose of 5 mg pindolol (P) and 100 mg metoprolol (M) were assessed in a double-blind study in 30 patients undergoing oral surgery. 2 Systolic and diastolic blood pressures and heart rate were reduced 90 min after oral medication and did not exceed initial values at rest during the procedure. 3 Noradrenaline, adrenaline and c-AMP concentrations did not differ at any time from the control values at rest after P, but were increased after local anaesthesia and during oral surgery after M as were the metabolic responses reflected by plasma concentrations of glucose and free-fatty acids. 4 Plasma levels of ACTH and cortisol showed the typical increase during the procedure, being independent of beta-adrenoceptor blockade. In contrast to the cardioselective antagonist M, prophylactic administration of the non-selective drug P prevented the sympathetic and metabolic responses to the stress of oral surgery. 5 Hypothalamic and adrenal stimulation were not reduced by either selective or non-selective beta-adrenoceptor blockade.

Adrenergic beta-Antagonists↗
PubMed1982

Management of cardiac arrhythmias with tiapamil.

37 patients with either chronic atrial fibrillation (AF), atrial premature beats (APBs) or ventricular premature beats (VPBs) received tiapamil as antiarrhythmic treatment. Tiapamil reduced A-V conduction by an average 20% in the group with AF (10 patients), the magnitude of response being dependent on the initial ventricular rate. In 3 of the 7 patients with APBs, the frequency of ectopic beats was reduced following a single i.v. injection of 1 mg/kg tiapamil. In patients with VPBs (n = 20), tiapamil (i.v. injection of 1 mg/kg followed by 4-hour i.v. infusion of 50 micrograms/kg/min in 10 patients) reduced ectopic beats by 30-50% in 6 cases, these all being patients who had not responded to previous antiarrhythmic therapy. The antiarrhythmic effect was maintained by i.v. infusion of 50 micrograms/kg/min for 4 h. The antiarrhythmic effect of tiapamil consists essentially in slowing A-V conduction and reducing chronic VPBs.

Adult↗
PubMed1982

[Age dependence of increase in heart rate after vagolysis (author's transl)].

Age dependent decrease of heart rate in sinus rhythm at rest was shown under clinical and experimental conditions and correlated with a decrease of sympathetic storage granula and membranes indicated by the tissue concentrations of c-AMP, which can be regarded as a messenger at the receptor sites. A slower maximal heart rate after Atropine and a reduced increase during oral medication with Ipratropium bromide can be explained by a reduced cardiac sympathetic threshold. The mentioned age dependent differences of the sympathetic stimulation can not be deduced to myocardial changes, because CPK and CK-MB activities were similar in the different age groups.

Adult↗
PubMed1982

[Enhancement of the antifibrillatory efficacy of quinidine in atrial fibrillation by verapamil (author's transl)].

We reported recently that in patients suffering from atrial fibrillation and being refractory to antifibrillatory therapy with quinidine conversion to sinus rhythm can often be achieved by additional doses of verapamil. To further evaluate the mechanism of this drug interaction, we studied the effects of quinidine, verapamil and combined quinidine-verapamil on the thresholds for electrically induced atrial repetitive extrasystoles (RET) and fibrillation (AFT). Comparative investigations were performed using the new calcium antagonist diltiazem. Our results show that verapamil provides protection against electrically induced atrial reentry arrhythmias only in combination with quinidine, but fails to exert a protective action when given alone. The increased success rate of conversion to sinus rhythm following combined quinidine-verapamil in patients with atrial fibrillation can be explained by an increase in the RET and AFT. The basic mechanism of this effect is supposed to be due to antiadrenergic properties of verapamil. In contrast to verapamil, diltiazen lacks the ability to increase RET and AFT in the presence of quinidine; diltiazen therefore cannot be expected to increase the antifibrillatory efficacy of quinidine in patients with atrial fibrillation.

Animals↗
PubMed1982

[Transvenous retrieval of endocardial pacemaker electrode fragments (author's transl)].

The management of septicemia associated with an infected endocardial pacemaker lead prerequisites removal of the latter nidus. If the infected electrode cannot be manually withdrawn, continuous traction may be employed. Should this attempted fail or should the severed end of the electrode fragment be inaccessible to a superficial approach, thoracotomy may be necessary. As an alternative procedure, we have successfully removed infected electrode fragments from three patients with septicemia by use of a Dotter retrieval catheter monitored with biplane fluoroscopy. The septicemia was subsequently irradiated in all cases.

Aged↗
PubMed1981

[Roentgenologic diagnosis of coronary vessel calcinosis in patients over 65 years of age].

215 out-patients aged between 65 and 88 years (average age 70.3 years) were examined radiologically for coronary calcification. In 62.5% of the cases positive results were obtained with a prevalence of men over women. From the 134 patients with coronary calcification 81.5% had a pathological ECG and 32% of these showed evidence of transmural infarction. The combination of coronary calcification and chronic arterial hypertension was found in 68.5% of the patients. In our opinion radioscopy of the heart for the detection of coronary calcification is of particular diagnostic value, on account of its safety and simplicity, especially with elderly patients; all the more so since the otherwise usual diagnostic techniques such as ergometry and selective coronary angiography can, for reasons of age, only be performed in certain cases.

Aged↗
PubMed1981

Sympathomimetic and cardiodepressant effects of acebutolol, oxprenolol, pindolol, and propranolol. A comparative study on changes in hemodynamics, contractility, heart rate, and AV-conduction time at therapeutic doses.

The present study was undertaken in order to obtain further informations on non-beta-antiadrenergic properties of the four beta-sympatholytic agents acebutolol, oxprenolol, pindolol, and propranolol. Standardized experiments were performed using a chronically reserpinized canine preparation for the assessment of dose-response curves of changes in hemodynamics, left ventricular contractility, heart rate, AV-conduction time, and myocardial oxygen consumption especially at therapeutic doses. Our results show that acebutolol and oxprenolol, at doses clinically recommended, exert moderate positive inotropic effects but do not influence heart rate significantly. Pindolol has a strong both positive chronotropic and inotropic efficacy, even at small therapeutic doses. Propranolol produces neither chronotropic nor inotropic effects. In contrast to the literature acebutolol exerts direct cardiodepression at doses clinically used, whereas oxprenolol, pindolol, at propranolol have no direct cardiodepressant properties at those doses. Thus the relationship between the dose requirements for chronotropic and inotropic sympathomimetic effects differs for each beta-sympatholytic agents, and in may prove impossible to get an order of intrinsic sympathomimetic potency of beta-blockers comparing dose-response curves of heart rate changes only. As shown in the case of acebutolol, direct cardiodepression of beta-sympatholytic agents may occur at therapeutic doses.

Acebutolol↗