1/26. Infradian rhythm of paroxysmal atrial fibrillation. A case report.To examine the circadian and infradian rhythms of paroxysmal atrial fibrillation, the time and date of 85 arrhythmic attacks occurring over a period of 4 years were analyzed in a patient with reliable symptoms. In the hourly analysis, a remarkable circadian rhythm similar to the reported population circadian rhythm was observed. On a day basis, the distribution of the intervals between 2 successive episodes showed a significant departure from the exponential distribution, indicating the arrhythmia was not a simple probabilistic phenomenon. spectrum analysis revealed a prominent peak occurring at about 0.3 cycles/day, suggesting a possible circasemiseptan rhythm. Thus, in this patient, paroxysmal atrial fibrillation was not a random event when observed not only from an hour incremental perspective but also from a day incremental perspective, suggesting the circadian and infradian rhythms of this arrhythmia.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
2/26. Transient appearance of antegrade conduction via an AV accessory pathway caused by atrial fibrillation in a patient with intermittent wolff-parkinson-white syndrome.A 55 year old man with intermittent Wolff-Parkinson-White (WPW) syndrome had an episode of atrial fibrillation (AF) that lasted for 117 days. After interruption of the AF a Delta wave appeared that lasted for two days and then disappeared. exercise stress and isoprenaline infusion could not reproduce the Delta wave, but after another episode of AF which lasted for seven days a persistent Delta wave appeared that lasted for six hours. In an electrophysiological study performed on a day without a Delta wave, neither antegrade nor retrograde conduction via an accessory pathway was seen, but after atrial burst pacing (at 250 ms cycle length) for 10 minutes, a Delta wave appeared lasting for 16 seconds. Atrial electrical remodelling-that is, the shortening of the atrial effective refractory period caused by AF, is a possible mechanism of the appearance of the Delta wave.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
3/26. Exit block of focal repetitive activity in the superior vena cava masquerading as a high right atrial tachycardia.An unusual case of atrial tachycardia (AT) originating from the superior vena cava (SVC) is reported. A 34-year-old man without structural heart disease underwent catheter ablation for drug-resistant AT. During the tachycardia, low-amplitude spiky electrograms with a cycle length of 120 to 175 msec were recorded in the SVC and exhibited 2:1 exit block to the atria, masquerading as the atrial activation observed with high right AT. These spiky electrograms also were observed during sinus rhythm, but they appeared immediately after the local atrial electrograms. The spikes were traced to a point 3 cm above the junction of the right atrium. Radiofrequency ablation at the site of the earliest appearance of the spike in the SVC successfully eliminated the tachycardia. During the following 15 months, no clinically significant atrial arrhythmias, including atrial fibrillation, occurred. This report indicates that careful mapping, including inside the SVC, will be a requisite in patients with high right atrial tachyarrhythmias.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
4/26. A patient with "atrial torsades de pointes".A patient with long qt syndrome and a history of palpitations underwent electrophysiologic study. Runs of polymorphic self-terminating atrial tachyarrhythmias were easily induced and occurred spontaneously several times. Atrial monophasic action potential (MAP) durations were prolonged at short pacing cycle lengths. Premature high right atrial extrastimuli prolonged MAP durations in the low right atrium, resulting in an inverse electrical restitution curve, and increased dispersion of repolarization. MAP morphology showed gradually increasing early afterdepolarizations. When the arrhythmia was initiated, a new action potential reproducibly emerged from these afterdepolarizations. To the knowledge of the authors, this is the first reported case of "atrial torsades de pointes" in a patient.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
5/26. Premature depolarization concealed in two pulmonary veins.A case is presented in which a premature depolarization emanated from a partially activated left inferior pulmonary vein, activated the entire left superior pulmonary vein, but did not activate the atria ("concealed"). The site of conduction block between each vein and the left atrium was the anatomic atriovenous junction. At times, the same depolarization would activate the atria and initiate atrial fibrillation. The shortest depolarization coupling interval that activated the atria was significantly longer than the atrial fibrillation cycle length recorded in either vein. Observations in this case support two concepts: (1) the existence of myocardial "tracts," extending into and between pulmonary veins; and (2) a "mismatch" between pulmonary vein activation ingress and egress.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
6/26. ventricular fibrillation induced by rapid atrial rates in patients with hypertrophic cardiomyopathy.AIMS: To describe the mechanisms of induction of ventricular fibrillation (VF) by rapid atrial rates in patients with hypertrophic cardiomyopathy (HCM). methods: Electrophysiological studies, management and follow-up in three patients with HCM with VF induced by atrial pacing. RESULTS: In one patient, spontaneous sinus tachycardia triggered VF. In another patient, VF occurred after verapamil infusion during rapid atrial fibrillation, and in the remaining patient there was no clinical VF. In all three patients, short runs of atrial pacing (cycle length 272-380 ms) induced VF, and QRS widening preceded fibrillation in all patients. Marked ventricular electrogram fragmentation was documented in one patient during atrial pacing and in another patient during late ventricular extra-stimuli. hypotension was associated with sinus tachycardia in one patient. The two patients developing clinical VF underwent atrioventricular (AV) junctional ablation; a ventricular defibrillator was implanted in one, and a mode-switching dual-chamber pacemaker in the other. No arrhythmic events occurred during 34- and 35-month follow-up, respectively. In the other patient, postatrial fibrillation pauses caused syncope, and he is asymptomatic 52 months after implantation of a dual-chamber pacemaker. CONCLUSIONS: Rapid atrial rates can trigger VF in some patients with HCM, probably through a combination of electrophysiological and ischaemic mechanisms. AV junctional ablation may prevent VF in selected cases.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
7/26. High-resolution mapping of tachycardia originating from the superior vena cava: evidence of electrical heterogeneity, slow conduction, and possible circus movement reentry.Superior Vena Cava Reentry. High-resolution mapping of a tachycardia originating from the superior vena cava (SVC) in a patient with atrial fibrillation is described. Unidirectional circuitous repetitive activation encompassing the full tachycardia cycle length was documented around a line of block within the myocardial sleeve of the SVC. Intermittent conduction to the right atrium resulted in an irregular atrial tachycardia. Evidence of electrical heterogeneity and slow conduction persisted in sinus rhythm and was exaggerated by premature stimulation but did not reproduce the activation pattern during tachycardia. All the available evidence is best compatible with circus movement reentry within the SVC, with marked slow and anisotropic conduction responsible for the restricted dimensions of the reentrant circuit. These findings may suggest a similar substrate and arrhythmia mechanism in the myocardium of the pulmonary veins.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
8/26. Electrical disconnection of an arrhythmogenic superior vena cava with discrete radiofrequency current lesions guided by noncontact mapping.This case describes a 54-year-old patient with paroxysmal atrial fibrillation and atrial flutter. Conventionally recorded local electrogram demonstrated a cycle length of 245 ms in the SVC which was conducted to the right atrium in a 2:1 fashion. The analysis of the virtual unipolar local electrogram from the noncontact mapping system demonstrated slow conduction between SVC and right atrium orthogonal to the atrial breakthrough in the upper part of the crista terminalis. RF ablation at the atrial breakthrough induced the electrical disconnection between the CVC and the right atrium.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
9/26. Persistent tachycardia with a 2:1 exit block within an isolated pulmonary vein.We describe a patient with drug-resistant, paroxysmal atrial fibrillation who underwent segmental pulmonary vein (PV) isolation. After complete isolation of the right superior PV, a persistent regular tachycardia was recorded within the vein. A tachycardia focus with a cycle length of 114 ms was found 2.5 cm away from the ostium of the PV. The cycle lengths of the PV tachycardia near the ostium and near the focus were 400 ms and 200 ms, respectively, which indicates the presence of a 2:1 exit block within the vein. This PV tachycardia was completely eliminated with the application of radiofrequency energy at the focus.- - - - - - - - - - ranking = 2keywords = cycle (Clic here for more details about this article) |
10/26. atrial fibrillation following chemotherapy for stage IIIE diffuse large B-cell gastric lymphoma in a patient with myotonic dystrophy (Steinert's disease).The authors describe the unusual association between diffuse B-cell gastric lymphoma and myotonic dystrophy, the most common form of adult muscular dystrophy, and sudden atrial fibrillation following one cycle of doxorubicin-based chemotherapy in the same patient. atrial fibrillation or other cardiac arrhythmias are unusual complications in patients treated with chemotherapy. The cardiac toxicity intrinsically associated with the aggressive chemotherapy employed could function as a triggering factor for the arrhythmia in the predisposed myocardium of this patient.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
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