Search PubMed⌕ Search

Biomedical subjects

V Hombach

Publications and source records attributed to V Hombach.

At least 235 records · Page 13Linked to original sources
PubMed1982

[The significance of the spinal averaging technique in cardiology (author's transl)].

This paper gives a survey on the principles, methodology, and clinical applications of the signal-averaging technique. Bioelectric signals of the heart at the microvolt level are overwhelmed by basal noise in high-gain amplified EKG registrations. By summation and averaging of several hundreds of cardiac cycles, basal noise can be minimized and the signal of interest accumulates. This improvement of the signal-noise ratio primarily depends on the number of cycles averaged, e.g., by 10:1 when 100 cycles are averaged (approximately, the square root of the number of averaged cycles). At present, signal-averaging computers in use are rather variable with respect to data acquisition, filter settings, trigger mechanism/stability, and data processing. These properties have to be taken into account when the results of different groups using different types of averaging computers have to be compared. At present, several applications of the signal-averaging technique in clinical cardiology have been proposed: (1) Surface EKG--registrations of pre-P potentials, of His bundle potentials, and of ventricular late potentials, as well as analysis of the frequency spectrum of the QRS complex in patients with myocardial infarction; (2) intracardiac EKG--recordings of pre-P potentials and of A-V nodal potentials; (3) surface phonocardiogram--detection of low-amplitude, late diastolic signals; (4) Intracardiac pressure analysis--recording of average phasic pressure changes. The most promising and clinically proven application of the signal-averaging technique, at present, seems to be the registration of His bundle potentials as well as of ventricular late potentials from the body surface. Future efforts will need to be made to record cardiac microvolt potentials beat by beat from the body surface by means of specially designed EKG recorders.

Arrhythmias, Cardiac↗
PubMed1982

Electrophysiological effects of cardioselective and non-cardioselective beta-adrenoceptor blockers with and without ISA at rest and during exercise.

1 In 46 patients (16 female and 30 male), aged between 18 and 73 years and effect of acute beta-adrenoceptor blockade with i.v. pindolol, acebutolol and atenolol has been studied at rest and during ergometric exercise, during routine intracardiac His bundle investigations. 2 At rest the functional parameters of the sinus node were impaired most markedly by atenolol. A-V nodal conduction was more depressed with acebutolol and atenolol than with pindolol. The His-Purkinje system conduction remained unaffected by all three beta-adrenoceptor blocking agents. 3 During ergometric exercise the depressant action of beta-adrenoceptor blockade on sinus nodal function with lower heart rates and on A-V nodal conduction with slower conduction velocities was equieffective with pindolol, acebutolol and atenolol. His-Purkinje system conduction again remained unchanged with one exception that after administration of pindolol, conduction rate during exercise was faster than before beta-adrenoceptor blockade. 4 It may be concluded that, in patients with low heart rates, an antagonist such as pindolol with relatively pronounced intrinsic sympathomimetic activity can be considered to be the drug of choice. In contrast, patients with higher heart rates at rest should be treated with a cardioselective betablocker without ISA. Patients with overt Sick Sinus Syndrome should not be given beta-adrenoceptor blockers at all. 5 Physical activity may change (improve or impair) the antiarrhythmic potency of beta-adrenoceptor blockers used in the treatment of supraventricular tachycardias or tachyarrhythmias.

Acebutolol↗
PubMed1982

[Valve replacement for mitral in incompetence in a patient with osteogenesis imperfecta (author's transl)].

Reports on aortic and mitral valve alterations in patients with osteogenesis imperfecta, a congenital connective tissue disorder, are sparse in the literature. Aortic valve incompetence is more common than mitral valve dysfunction. Though the clinico-pathological and histological features of valve alterations are very similar to those seen in Marfan's Syndrome, valve dysfunctions in osteogenesis imperfecta are rarer than in Marfan's Syndrome. In a 23-year-old patient with typical clinical feature of osteogenesis imperfecta, mitral incompetence was detected by echo- and angiography. Patient was provided with a St.-Jude-Medica prosthesis and postoperative course was without any complications.

Adult↗
PubMed1981

Antiarrhythmic effects of acute betablockade with atenolol on supraventricular tachycardias at rest and during exercise.

In a total of 18 patients, 7 females and 11 male patients with ages ranging from 23 to 70 years (mean: 45.5 +/- 14.5) diagnostic His bundle studies incorporating programmed atrial and ventricular pacing for the induction of tachycardias was performed before and after betablockade with the cardioselective betablocking agent atenolol, in a dose of 5 mg given iv. over 3 to 5 minutes. In 7 patients the pacing procedure could be repeated following ergometric exercise in order to evaluate the influence of a raised sympathetic tone on the conditions initiating paroxysmal tachycardias. At rest, atenolol prevented the pacing induced tachycardias (20 dysrhythmias in 18 patients) in 3/5 individuals with Wolff-Parkinson-White (WPW)-syndrome, in 4/6 cases with atrial tachycardias, in 4/6 patients presenting atrial flutter, in 2/2 cases developing AV-nodal tachycardias and in 1/1 individual with ventricular tachycardia. Thus, in 13 out of 19 (68%) supraventricular dysrhythmias patients benefitted from atenolol by preventing or controlling the tachycardia. Ergometric exercise changed the tachycardia or echo zone in 5/8 arrhythmias after betablockade when compared to the controls before administration of atenolol (3/5 improvement by narrowing of the tach- or echo zone, 1/5 prevention of tachycardia, 1/5 impairment due to widening of the tachycardia zone). Considering only the prevention of tachycardias, the antiarrhythmic potency of atenolol was improved in one patient with pacing induced flutter and impaired in one individual with a WPW syndrome, by ergometric exercise. These results suggest that atenolol seems to provide a good antiarrhythmic action, especially in supraventricular tachycardias, and that an increased sympathetic tone during exercise may modify the antidysrhythmic strength of betablockade.

Adult↗
PubMed1981

[Non-invasive derivation of potential of the bundle of His from the body surface (author's transl)].

In 17 of the 28 patients a surface potential of the bundle of His could be differentiated. Pharmacological tests with verapamil and ajmaline raised the number of positive body surface recordings of the bundle of His to 22 out of 30 (=73%). In 11 of the 30 subjects (=37%) depolarizations of the Tawara bundle branches were recorded in addition. Two possible applications of this method are discussed: follow-up of patients with AV-block and supervision of negative dromotropic cardiac medication.

Adult↗
PubMed1980

Effects of a beta 1-selective adrenergic agonist in normal human volunteers.

In healthy volunteers, the effects of prenalterol, a new beta 1-adrenoceptor agonist, on renal hemodynamics, excretory function, plasma-renin-activity, plasma cAMP concentration, and plasma and urinary norepinephrine were studied. Besides an increase in blood pressure, which was adjusted to about 20 mmHg above the resting values, and an increase of heart rate, prenalterol induced only transient decreases of urinary volume and free water clearance and in increase of sodium excretion. The other parameters measured did not change. Thus prenalterol mainly exerts positive inotropic and chronotropic effects and does not affect renal circulation.

Adrenergic beta-Agonists↗
PubMed1979

An approach to direct detection of sinus nodal activity in man.

We are reporting a series of 13 out of a total of 16 patients in whom sinus nodal activity was recorded with the use of intra-atrial electrodes, during diagnostic His-bundle electrocardiography investigations. The protocol consisted of the simultaneous monitoring of the following intra-atrial points: high right atrium, low lateral right atrium, left atrium and the His-bundle electrogram (HBE), which accompanied the detecting sonde placed as a loop in the superior vena cava, with the electrodes facing the sinus nodal area. This permitted an adequate assessment of the sequence of the depolarizing activity. All patients showed sinus nodal potentials preceding the initiation of the P-wave in the surface-EKG or the atrial potential in the high right atrial lead, respectively, in the range of 60 to 270 msec depending upon the functional status of the sinus node in each patient. Such waves were clearly separated from the initiation of the atrial potential by an isoelectric line and showed functional traits compatible with the S-A nodal functions, as many authors have previously reported in experimental animal models. The text contains a review of the relevant literature and discussion upon the diagnostic significance of this method in the assessment of sinus nodal disease.

Adult↗
PubMed1979

[The direct detection of sinus nodal potentials in man by means of the signal-averaging technique (author's transl)].

In 13 patients in the age range of 34 to 70 years (mean: 53 +/- 10 years), during diagnostic His-bundle investigations, registrations from the sinus nodal area were analyzed with a signal-averaging computer. In 12 patients we were able to get reproducible per-P-potentials with a sino-atrial conduction interval between 56 and 227 ms. The normal sequence of the excitation process from the atrium to the AV node together with the bundle of His and to the ventricles in all patients, and the reproducibility of the signal-averaged pre-P-potentials, which were well outlined from the atrial potential with a reasonable conduction interval, suggest that these signal-averaged pre-P-potentials reflect the sinus nodal activity rather than an ectopic focus. In 5 of 11 comparable cases there was a good correlation between the signal-averaged sino-atrial conduction intervals and those calculated with the extrastimulus technique. In 2 patients this correlation was moderate. The signal-averaging process may be impaired by coarse random noise, frequent atrial or ventricular extrasystoles, and by fluctuations of the baseline of the sinus nodal lead. The fact that the registrations are performed during normal undisturbed sinus rhythm offers a considerable advantage over the extrastimulus technique.

Action Potentials↗
PubMed1978

[Action of molsidomine on haemodynamics at rest and on exercise in patients who have coronary heart disease (author's transl)].

In ten patients with coronary heart disease molsidomine achieved a clear-cut decrease in pre- and after-load of the heart at rest. Due to decreased venous return at rest there was a fall in stroke volume resulting in a fall of systolic and diastolic aortic pressure. But at the same level of standardised exercise, systolic and diastolic arterial pressure and cardiac output were similar with or without molsidomine. Without changing after-load, there was a fall in pulmonary artery mean pressure (P less than 0.005), probably due to an increase in left-ventricular compliance and (or) a fall in pulmonary vascular resistance. A rise in venous capacity or a decrease in venous return during exercise was excluded as a possible mechanism of molsidomine action.

Adult↗