Sinus escape-capture bigeminy alternating with sinus extrasystolic bigeminy: dual atrial response and apparent sinus escape.

We report here five cases of sinus bigeminy in which comparatively long PP intervals alternated with comparatively short PP intervals, suggesting 'sinus escape-capture bigeminy' or 'sinus extrasystolic bigeminy'. In three of the cases, these two forms of sinus bigeminy were found in the same patient. This is the first study on 'sinus escape-capture bigeminy' alternating with 'sinus extrasystolic bigeminy'.

Parasystole due to re-entry as the possible mechanism of ventricular parasystole with second-degree entrance block.

Background: In 1974, Kinoshita reported a case of 'irregular parasystole' due to type I second-degree entrance block. Since then, many cases of such 'irregular' parasystole have been reported by us. To explain the mechanism of 'irregular' parasystole, two theories have been suggested, namely, 'electrotonic modulation' by Jalife and Moe, and 'type I second-degree entrance block' by us.

Apparent AV junctional escape in Wenckebach AV block: markedly slow conduction through the slow AV pathway.

We report here two cases of Wenckebach atrioventricular (AV) block in which apparent AV junctional escape was observed, but most likely resulted from markedly slow conduction through the slow pathway of dual AV junctional pathways. In these cases, it seems that a blocked P-wave was followed by an AV junctional escape beat. However, a blocked P-wave occasionally failed to be followed by an escape beat, and the RR interval containing the blocked P-wave was markedly longer than the above escape interval.

Paroxysmal atrial fibrillation initiated by late coupled atrial extrasystoles.

A Holter recording was taken from a 62-year-old man, in whom paroxysmal atrial fibrillation was often initiated by late coupled extrasystoles rather than by close coupled ones. Coupling intervals of the extrasystoles to the preceding sinus P waves were considerably variable. When the coupling interval of an extrasystole was shorter than a critical period of 0.

Apparent disappearance of ventricular parasystole due to a marked difference between the long form and the short form of the ectopic cycles.

Electrocardiograms were taken from a 44-year-old man with irregular ventricular parasystole in whom pure parasystolic cycles without any intervening nonectopic QRS complexes were found. When a sinus impulse fell late in the parasystolic cycle, it hastened occurrence of the next parasystolic discharge. This suggested that type I second degree entrance block occurred in the re-entrant pathway containing the parasystolic focus.

Accessory-pathway block on alternate beats in the Wolff-Parkinson-White syndrome: supernormal conduction as the mechanism.

The Holter monitor electrocardiograms were taken from 2 patients with intermittent Wolff-Parkinson-White syndrome. In these patients, when the heart rate was increased, accessory-pathway block on alternate beats was found and was maintained for a considerably long period. In one patient, when accessory-pathway block on alternate beats was found, a ventricular extrasystole occurred.

Apparent bradycardia-dependent right bundle branch block associated with atypical atrioventricular Wenckebach periodicity as a possible mechanism.

The Holter monitor electrocardiogram was taken from a 15-year-old male athlete. Intermittent right bundle branch block frequently occurred at rest. When sinus cycles gradually lengthened, sinus impulses were conducted to the ventricles with right bundle branch block (RBBB) in succession.

Atrial escape-capture bigeminy in dominant atrial rhythm with 2:1 exit block.

A 27-year-old woman with atrial bigeminy is reported in whom long PP intervals alternate with short PP intervals. All P waves are negative in lead II and all PR intervals measure 0.12 s.

Alternating reversed wenckebach periodicity: Concealed electrotonic conduction as a possible mechanism.

Electrocardiograms were taken from a 67-year-old man with 2:1 atrioventricular block in whom alternating reversed Wenckebach periodicity was found. Long PR intervals of alternately conducted P waves progressively shortened until an alternate P wave was blocked. After an alternate P wave was blocked, the next alternate P wave was conducted to the ventricles with a markedly long PR interval.

Atypical atrioventricular Wenckebach periodicity caused by conduction through triple atrioventricular junctional pathway as a probable mechanism.

Electrocardiograms were taken from an 84-year-old man with right bundle branch block in whom atypical atrioventricular Wenckebach periodicity was frequently occurred. The electrocardiographic findings as mentioned below suggested that the atypical periodicity was caused by conduction through triple atrioventricular junctional pathways as a probable mechanism. When a P wave was blocked after a markedly prolonged PR interval of 0.

"Sinus node" reentrant tachycardia associated with respiration.

A 77-year-old woman (case 1) and a 57-year-old woman (case 2) with paroxysmal "sinus tachycardia" are reported in whom the tachycardia repeatedly occurred associated with respiration. In both cases, reentrant P' waves are almost the same in configuration as sinus P waves, and P'R intervals are also the same in length as PR intervals. In case 1, the tachycardia was initiated during inspiration, and was terminated during expiration; showing tachycardia-dependent initiation.

Apparent bradycardia-dependent advanced second-degree atrioventricular block.

A 65-year-old man with repeated chest discomfort and dizzy spells was transferred by an emergency car. On the way to hospital, his pulse was palpable as regular 4 to 5 beats followed by an unpalpable period of about 4 s. His electrocardiographic monitor showed that 4 to 5 sinus QRS complexes were followed by consecutive 3 to 4 blocked sinus P waves, which occurred repeatedly.

Double ventricular response caused by longitudinal dissociation in the his bundle.

Electrocardiograms were taken from a 36-year-old woman with normal sinus rhythm in which 4 types of QRS complexes and 2 types of fusion QRS complexes were found in configuration. To interpret this arrhythmia, we proposed 3 unique mechanisms: a) double ventricular response through the fast pathway mainly directing to the right bundle branch and the slow pathway mainly directing to the left bundle branch, b) longitudinal dissociation in the His bundle, and c) transverse conduction in the lower edge of the dissociation. Although functional longitudinal dissociation in the atrioventricular node has been reported, longitudinal dissociation in the His bundle is a rare arrhythmia.