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Biomedical subjects

T Pop

Publications and source records attributed to T Pop.

At least 127 records · Page 7Linked to original sources
PubMed1977

Alternans in human atrial monophasic action potenial.

This report describes the case of a patient with a supraventricular tachycardia with a ventricular rate of 109/min and no visible P waves in the electrocardiogram. The recording of the monophasic action potential of the right atrium disclosed an atrial tachycardia with a rate of 218/min. There was an alternans of the phase 2 of repolarisation in the action potential. This report emphasises the fact that the phenomenon of alternans occurs in man, as in the experimental animal, at a cellular level.

Action Potentials↗
PubMed1977

[The relation between the electrophysiological parameters of the right atrium and the AV-node conduction (author's transl)].

40 patients were examined with the extrastimulus method at 3 different driving rates (80, 100 and 120/min). It was found that the atrial conduction velocity during the relative refractory period sometimes explains a paradoxical conduction of a premature atrial beat. The AV-node conduction is mainly determined by the correlation between the functional refractory period of the right atrium (FRPRA) and the effective retractory period of the AV-node (ERPAVN). With increasing driving rate the FRPRA shortened while ERPAVN lengthened. This explains why in this study the number of patients in which the ERPAVN could be reached progressively increased from 23 at a driving rate of 80/min to 31 and 33, respectively, at the driving rates of 100 and 120/min.

Adolescent↗
PubMed1977

[The electrophysiologic constellation of the so-called "sick sinus syndrome" (author's transl)].

A comparative investigation of the electrophysiological properties of the sino-atrial node, the right atrium, the AV-node, and the intraventricular conduction system was performed in 37 patients. 18 patients had a sino-atrial block, 8 a persistent bradycardia and 11 a brady-tachy syndrome. There are the following conclusions: 1. The greatest dysfunction of the sino-atrial node was observed in the group of patients with sino-atrial block. This can be derived from the determination of the sinus node recovery time and from the occurrence of secondary pauses. 2. The vulnerability of the right atrium, investigated by the extra-stimulus-technique, is enhanced in the brady-tachy syndrome. Measuring the duration of the P-wave and the PA-interval does not give any information about the atrial dysfunction. 3. Patients with a sino-atrial block often have a disturbed AV-node conduction. In most patients it is latent only and easily can be detected by atrial incremental pacing. 4. A hemiblock or bundle branch block is found more often in patients with sino-atrial block and sinus bradycardia than in patients with the brady-tachy syndrome. By the registration of a His-bundle-electrogram a trifascicular block can be uncovered in half of these patients. 5. In the sick sinus syndrome, there is always the possibility of additional dysfunctions in the conduction distal to the sino-atrial node. With special regard to therapeutic measures, a complete evaluation can only be made by of both endocardial recording and stimulation methods.

Adult↗
PubMed1976

[The vulnerability of the human atrium. I. Correlations between vulnerability, sinus node recovery time and intraatrial conduction time (author's transl)].

Using the extrastimulus method in 100 patients, premature impulses were applied during the relative refractory period of the right atrium. Depending on the atrial response to these impulses we divided our patients in the following 3 groups: Group A: no repetitive firing (61 patients); group B: 1 to 5 additional atrial extrasystoles with a total duration of maximum 1.5 s (27 patients); group C: runs of atrial flutter or fibrilation for at least 8 s (12 patients). The statistical analysis of the following parameters: age, PA interval, absolute and corrected sinus node recovery time did not show any significant difference between the 3 groups. These results suggest that the investigated parameters are of no great importance in the genesis of the atrial vulnerability.

Adolescent↗
PubMed1976

[Intra-atrial conduction disorders of 2d degree].

Five patients with second degree intraatrial block are presented. The first three cases had a sick sinus syndrome with sinus bradycardia, broad P waves and episodes of atrial flutter or fibrillation. In these patients a Wenckebach phenomenon could bei elicited by atrial stimulation at a critical driving rate between the stimulated site and the recording electrode. In the first patient this conduction disturbance was obtained at several right atrial stimulation sites. The block could be elicited in the other two patients only in a limited area of the right atrium respectively only by left atrial pacing. In the remaining two patients an atrial tachycardia with block was observed. The intraatrial conduction disturbance was manifested as an exit block around the ectopic pacemaker. In one patient the tachycardia was induced by digitalis intoxication. In the other patient no etiologic factor of the tachycardia could be found. While the first three patients presented intraatrial conduction disturbances already in sinus rhythm, the last two cases showed after recovery from the atrial tachycardia P waves of normal duration and configuration.

Aged↗
PubMed1975

[Localization of the conduction defect in complete A-V block by means of His bundle electrograms (author's transl)].

The localization of the conduction defect in so-called complete A-V block can be established by electrocardiography only indirectly and unreliably. In principle the region of the atrio-ventricular junction, i.e. the A-V node and the bundle of His, may be involved just as well as the two branches. Analysis of the configuration of the QRS complex in the electrocardiogram is unreliable, particularly in cases with bundle branch block, because any pattern can arise from the appropriate site of a tertiary focus of stimulation in one of the two ventricles. Recording His bundle potentials (His bundle electrogram) enables differentiation. In eleven personal observations and 151 cases collected from the literature of complete A-V block the analysis with this method showed that the so-called A-V block in the majority of cases (63%) is actually due to bilateral bundle branch block. In the other 37% an A-V junctional block was present. This type of block could be differentiated by means of His bundle electrograms into an A-V nodal block and His bundle block.

Adult↗
PubMed1975

[Atrial standstill (author's transl)].

A patient with a persistent form of atrial standstill is presented. The rarity of this arrhythmia is emphasized and the possible mechanisms involved and the diagnostic criteria are discussed.

Action Potentials↗
PubMed1975

[Hemodynamic compensatory mechanisms of impaired left ventricular contraction in coronary artery disease (author's transl)].

The effect of chronic coronary insufficiency on the hemodynamics, the geometry and muscle mass of the left ventricle were studied in 30 patients and compared to 13 controls. In these patients the cardiac output was normal in spite of impaired contractility and left ventricular wall movement. The impaired cardiac performance was compensated by 1. hypertrophy and 2. dialatation of the left ventricle. In one-vessel disease of the the coronary arteries left ventricular muscle mass was modestly, but not significant increased. Hypertrophy decreased from +20% in one vessel disease to +10% in three vessel disease. In contrast, left ventricular dilatation increased from +23% in one vessel disease to 43% in two vessel disease and to 70% in patients with sclerotic lesions in three vessels. Left ventricular dilatation seems to be the main hemodynamic compensatory mechnism resulting in a relative increase of the pump function of the heart compared to non dilated hearts. However, dilatation leads in the end-phase to left ventricular failure. By increased wall tension in the presence of impaired coronary blood flow dilatation bears the risk of deterioration of left ventricular function.

Adult↗
PubMed1975

An atrionodal and nodo-Hisian gap phenomenon.

Two cases of the gap phenomenon are presented. The first was an example of a gap between the atrium and the AV node. In the second the gap was at the nodo-Hisian junction. At a critical H1H2 interval splitting of the premature His potential occurred. A decrease of the H1H2 interval led to the disappearance of the distal H2 potential and to atrioventricular block. But at even shorter coupling intervals the H1H2 interval lengthened suddenly with resumption of the AV conduction. These observations provide further evidence that the gap phenomenon has a wider spectrum than was previously thought.

Adult↗
PubMed1975

[Atrial re-entry tachycardia].

By means of coupled atrial stimulation short bouts of atrial tachycardia could be elicited in a 61-year-old patient. As an explanation for this unusual response to stimulation a reentry phenomenon within the atria is postulated.

Bundle of His↗