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PubMed1978

The electrocardiographic diagnosis of left septal fascicular block.

In 38 anesthetized and intubated dogs QRS features were estimated after incision of the interventricular septum. The left bundle branch system of the excised heart was stained with Lugol solution to visualize the extent and localization of the fascicular section. In 7 dogs the incision reached a part of the septal network; three of them showed incomplete LBBB pattern. In 13 dogs a major part of the septal network and the posterior/anterior fascile were transected. In 6 of them the pattern of incomplete LBBB was noted. A bipolar intracavitary L-R lead was recorded in 2 of these cases and revealed disappearance of the initial q wave in both. In 7 experiments the left bundle branch was completely transected with consecutive LBBB pattern. In 8 dogs the incision failed to reach the left bundle branch system and the ECG records did not show any form of LBBB pattern. The findings suggest that incomplete LBBB may be a form of left septal fascicular block.

Animals↗
PubMedDate not supplied

Ventricular monophasic action potentials during intermittent left bundle branch block.

A case of intermittent left bundle branch block is presented. Simultaneous recording of right and left ventricular monophasic action potentials allowed a more accurate demonstration of delayed left ventricular activation during intermittent left bundle branch block. His bundle electrogram was also of great help in the interpretation of infrahisian conduction in the patient studied. These methods may be useful in the complex electrophysiologic investigation of certain cases.

Action Potentials↗
PubMed1976

[Adverse effects of drugs: syncope due to prenylamine (author's transl)].

The authors report on 4 Intensive Care Unit cases, hospitalized for syncopes due to serious ventricular arrhythmias. They all presented long Q-T and were receiving treatment with prenylamine. Improvements were observed on suspension of the drug, suggesting therefore that during this treatment, frequent electrocardiographic checks, especially for elderly patients, should be carried out. Caution should also be exercised in associations with other chinidinosimiles and hypokaliemic drugs

Aged↗
PubMed1978

[The antegrade GAPs (author's transl)].

GAP in a-v conduction is defined as a zone within the cardiac cycle where premature atrial impulses fail to evoke ventricular responses whereas atrial beats of greater and lesser prematurity do. This phenomenon occurs when the effective refractory period (ERP) of a distal site is greater than the functional refractory period (FRP) of a proximal site of the conduction system. To date, Damato and Co. classify antegrade gaps into six types on the basis of blocks location and proximal delay that permits conduction recovery: type I: HPS and AVN; type II: HPS (distal) and HPS (proximal); type III: HPS and His-bundle; type IV: AVN (distal) and AVN (proximal); type V: AVN or HPS and atrium; type pseudo-V: AVN or HPS and antrial miocardium proximal to stimulation site; type VI: HPS and supernormality (no proximal delay). The Authors propose, on the basis of 37 cases of GAP phenomenon observed in 185 electrophysiological studies, a new classification of antegrade gaps, which complete and partially modifies Damato's one. Tyes I-II-II-IV and V are divided into A and B forms according to the type and the site of the distal block. GAP type VI is replaced by Damato's pseudo-V. Two new types are proposed: in the first (type VII) the distal block is in the atrium and the proximal delay is in atrial miocardium proximal to stimulation site; in the second (type VIII), in subjects with pre-excitation, the block is in the accessory pathway and the proximal delay is in atrium.

Adolescent↗
PubMed1978

Cardiac conduction abnormalities and Stokes-Adams attacks in myotonic dystrophy.

Myotonic dystrophy is a well known cause of cardiomyopathy. While various cardiac conduction abnormalities have been described in patients with myotonic dystrophy, so far only sporadic cases of Stokes-Adams attacks have been reported. Of 27 patients with this disease various conduction disturbances were detected in 17 (63%), 5 of whom presented with Stokes-Adams attacks and were found to have intracardiac conduction defects. The prognosis in four of the five patients was greatly improved with permanent pacemaker implantation.

Adams-Stokes Syndrome↗
PubMed1978

Asynchronous conduction in the human His bundle.

2 patients with symptoms of paroxysmal AV block showed widening, splitting, slurring and decreasing amplitude of the His potential. Concomitantly, this was followed by different patterns of bundle branch block. In one of the patients it was obvious that a left bundle branch block was related to a Wenckebach phenomenon in the His bundle, and in the other patient different bundle branch block patterns were related to the occurrence of the intra-His bundle conduction delay. It is suggested that the present electrophysiological findings reflect asynchronous conduction in the His bundle causing a critical conduction delay in parts of the bundle branches leading to bundle branch block.

Aged↗
PubMed1979

[State of the heart conduction system in the sick sinus syndrome (according to the recording of the bundle of His potentials and the atrial stimulation test)].

It was established that the presence of Samoilov-Wenckebach's periods and prolongation of the H--V interval at low frequency of the imposed rhythm as well as periods of asystolia of more than 1,200 msec are most typical for these patients. An attempt was made to determine the type of cardiac stimulation indicated for such patients from the character of the disorders of rhythm observed in them and the initial frequency of their own cardiac contractions.

Action Potentials↗
PubMed1979

[Treatment of severe ventricular arrhythmia by means of repeated cardiac stimulation].

The overdrive pacing method is widely used now in clinical practice for prevention and treatment of severe ventricular disorders of the cardiac rhythm. The mechanisms of arrhythmia suppression by means of this stimulation is analysed. Indications are determined for the choice of the site of stimulation and optimal impulce frequency in ischemic heart disease, and overdosage with digitalis drugs, as well as in myocardiopathy.

Adult↗
PubMed1976

'Supernormal' phase in hemiblock conduction.

A case is described where the basic sinus rhythms is associated with an advanced degree of left anterior hemiblock. The rhythm is complicated by atrial extrasystoles, associated with a lesser degree of left anterior hemiblock. This paradox of 'supernormality' is explained on a critical interplay of differential refractoriness within the divisions of the left bundle-branch.

Adult↗
PubMed1978

Electrophysiological properties of intravenous metoprolol in man.

Electrophysiological changes produced by intravenous (0.1 mg/kg) metoprolol, a new selective beta 1-blocking agent devoid of intrinsic activity, were studied in 16 subjects with estimated normal impulse formation and conduction. The most important effects were sinus bradycardia, mild increase of sinoatrial conduction time, depression of intranodal conduction, and prolongation of AV node refractory periods. Sinus node recovery time and atrial refractory periods were unmodified. Infranodal conduction and the refractory periods of the His-Purkinje system, as well as of the bundle-branches, were unchanged. These effects are compared with those observed after intravenous propranolol, pindolol, and oxprenolol.

Adult↗
PubMed1978

Mahaim conduction producing left axis deviation and normal QRS.

An unusual patient is described in whom electrophysiological studies strongly suggest the occurrence of Mahaim conduction. The patient whose electrocardiogram previously showed a left anterior hemiblock pattern then developed advanced atrioventricular (AV) block (AH block). Beats conducted through the atrioventricular node always had a short HV interval (20 ms) and QRS complexes of left anterior hemiblock pattern. Junctional escape beats always had a normal HV interval (50 ms) with normal intraventricular conduction. His bundle pacing showed the StV interval and QRS contour of escape beats. These findings suggest the existence of an accessory pathway (Mahaim fibres) passing from the area of block, presumably the uppermost portion of the His bundle, to the posteroinferior division of the left bundle-branch. The surface electrocardiogram did not show the characteristic delta wave of the Wolff-Parkinson-White syndrome. Our observations suggest that patients in whom there is conduction along Mahaim fibres may show only the pattern of intraventricular conduction defect without a delta wave.

Cardiac Complexes, Premature↗