1/37. AV reentrant and idiopathic ventricular double tachycardias: complicated interactions between two tachycardias.An electrophysiological study was performed in a 61 year old man with Wolff- Parkinson-White (WPW) syndrome. At baseline, neither ventricular nor supraventricular tachycardias could be induced. During isoprenaline infusion, ventricular tachycardia originating from the right ventricular outflow tract (RVOT) with a cycle length of 280 ms was induced and subsequently atrioventricular reentrant tachycardia (AVRT) with a cycle length of 300 ms using an accessory pathway in the left free wall appeared. During these tachycardias, AVRT was entrained by ventricular tachycardia. The earliest ventricular activation site during the ventricular tachycardia was determined to be the RVOT site and a radiofrequency current at 30 W successfully ablated the ventricular tachycardia at this site. The left free wall accessory pathway was also successfully ablated during right ventricular pacing. The coexistence of WPW syndrome and cathecolamine sensitive ventricular tachycardia originating from the RVOT has rarely been reported. Furthermore, the tachycardias were triggered by previous tachycardias.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
2/37. Intermittent bundle branch blocks in a patient with uncommon-type atrioventricular nodal reentrant tachycardia and enhanced atrioventricular nodal conduction.We report on a patient with uncommon-type atrioventricular (AV) nodal reentrant tachycardia with a short tachycardia cycle length (235-270 ms), in whom transient wide QRS tachycardia with both left bundle branch block and right bundle branch block aberrancy were followed by narrow QRS complexes. In addition, His-ventricular (H-V) block and a sudden prolongation of the H-V interval occurred during the tachycardia. As the determinant of these unusual findings, the possibility that the anterograde limb of the reentry circuit has an enhanced AV nodal conduction property is discussed, as is the clinical significance of this type of tachycardia.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
3/37. Paroxysmal supraventricular tachycardia caused by 1:2 atrioventricular conduction in the presence of dual atrioventricular nodal pathways.One-to-two atrioventricular conduction, ie, the double response to a single sinus or atrial impulse, resulting in two QRS complexes for one P wave, is a rare manifestation of dual atrioventricular (AV) nodal pathways. This report describes the case of a 61-year-old woman with continuous episodes of supraventricular tachycardia caused by independent conduction to the ventricles of sinus impulses over both the fast and the slow AV nodal pathway, giving rise to a ventricular rate that was twice the sinus rate. A wide spectrum of electrocardiographic manifestations of 1:2 AV conduction was observed on the surface electrocardiogram. The diagnosis was suggested by several elements including evidence of dual AV nodal pathways during sinus rhythm and cycle length alternans during tachycardia. The patient underwent successful slow pathway ablation with complete disappearance of symptoms and electrocardiographic manifestations of 1:2 AV conduction.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
4/37. Facilitation of atrioventricular reentrant tachycardia by iatrogenic right bundle branch block.The present case report describes the diagnosis of a concealed bypass tract in the right lateral wall revealed by electrophysiologic evaluation performed in a patient with rare palpitations. A iatrogenic right bundle branch block (RBBB) caused the occurrence of an incessant atrioventricular reentrant tachycardia. The disappearance of the RBBB determined a very difficult induction of the tachycardia that, when induced, showed a shorter cycle length and ventriculoatrial interval than those observed during RBBB tachycardia. The presence of a RBBB ipsilateral to the right free wall accessory pathway provided a critical delay within the circuit thus allowing the bypass tract to recover excitability. This relevant delay also allows the sinus beat to initiate and stabilize the tachycardia thus rendering it incessant.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
5/37. Atrioventricular nodal re-entrant tachycardia with two functionally discrete fast pathways.We present a case with two forms of atrioventricular nodal re-entrant tachycardia (AVNRT) that revealed similar H-A-V sequences, but could be differentiated only by their retrograde atrial activation sequences. Both tachycardias were induced following anterograde slow pathway conduction, suggesting the slow pathway as the anterograde limb of the re-entry circuit. The earliest atrial activation site of one form was in the same region of the bundle of his as that of the common type of AVNRT, while that of the other form was the ostium of the coronary sinus. Properly timed extra-stimuli delivered from the atrium or ventricle during the latter tachycardia penetrated through the fast pathway without resetting the tachycardia cycle length. These rare phenomena suggest the existence of two functionally discrete fast pathways, of which the alternative pathway alters to become the more predominant retrograde limb according to time and circumstances.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
6/37. Radiofrequency ablation in a patient with atrioventricular reentrant tachycardia and atrioventricular nodal reentrant tachycardia with 2:1 atrioventricular block.The authors report the case of 15-year-old girl with a history of palpitations and shortness of breath during exercise. The electrocardiogram showed ventricular preexcitation suggesting a wolff-parkinson-white syndrome with a posteroseptal accessory pathway. During the electrophysiological study a left posterospetal accessory pathway was identified and an orthodromic atrioventricular reentry tachycardia was reproducibly induced (cycle length 400 ms). After disappearance of the ventricular pre-excitation with radiofrequency ablation, a dual physiology of atrioventricular node condution was documented and a slow-fast atrioventricular nodal reentrant tachycardia was repeatedly induced. Upon induction, this tachycardia presented a proximal atrioventricular block with 2:1 condution converted to 1:1 condution with overdrive pacing from the proximal coronary sinus (cycle length 270 ms). Radiofrequency ablation of the slow pathway was performed with success. We discuss the need to suspect and seek different arrhythmogenic substracts of tachycardia in a single patient, the electrophysiologic conditions that could explain the inducibility of different arrhythmias in this case, and the controversy regarding ablation of more than one reentry circuit in a single procedure.- - - - - - - - - - ranking = 1keywords = cycle (Clic here for more details about this article) |
7/37. Differentiation between parasystole and reentry in concealed bigeminy.There are two different theories to explain the mechanism of concealed bigeminy: one is '2:1 concealed reentry'; the other is 'irregular parasystole.' Two exemplary cases of the even-number variant of concealed bigeminy are presented. In case 1, the mechanism can be explained by an irregular parasystole due to a modulated parasystole; however, findings during temporary sinus arrest caused by vagal stimulation indicate that this case is not governed by a parasystole, but by a 2:1 concealed reentry. In case 2, the mechanism can be explained by a 2:1 concealed reentry without parasystole; however, findings during temporary sinus arrest indicate that this case is governed by an irregular parasystole due to a type-I second-degree entrance block. Thus, in cases of concealed bigeminy without pure ectopic cycles, it does not seem easy to explain the mechanism of concealed bigeminy on the theory of a modulated parasystole.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
8/37. A case of concealed WPW syndrome with three different reciprocal tachycardias due to triple AV nodal pathways.Triple atrioventricular nodal pathways (TAVNP) occur occasionally, but it is rare for them to produce more than two different tachycardias. Here we report a case of concealed WPW syndrome with three different tachycardias. During electrophysiologic studies, three different reciprocal tachycardias were induced. tachycardia #1 was characterized by a cycle length of 230 msec and an A'-H interval of 70 msec. For tachycardia #2, these parameters were 300 msec and 140 msec, while they were 370 msec and 200 msec for tachycardia #3. During all three tachycardias, the earliest atrial activity was observed in the left atrium. Ventriculoatrial conduction occurred following ventricular stimulation, and the earliest atrial activity was observed in the left atrium, indicating the existence of left-sided accessory pathway. Persistence of tachycardia for 15-30 min caused marked pulmonary congestion. The heart rate was very high (260 beats/min) during tachycardia #1, and the pulmonary arterial pressure rose to 40/30 mmHg, with the pulmonary arterial diastolic pressure remaining at about 30 mmHg throughout the tachycardia. It seems that the pulmonary venous pressure rises abnormally during paroxysmal supraventricular tachycardia with a very high heart rate and that pulmonary congestion can easily occur during a short period of tachycardia.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
9/37. Incessant automatic ventricular tachycardia complicating acute coxsackie B myocarditis.A 13-year-old girl presented with incessant ventricular tachycardia complicating acute Coxsackie B3 myocarditis. Electrophysiologic assessment revealed that the tachycardia could not be terminated, overdrive suppressed or accelerated by programmed electrical stimulation, but was transiently slowed by intravenous adenosine triphosphate and had marked spontaneous and sympathoautonomic-mediated fluctuation in the tachycardia cycle length. These features were atypical of reentry and triggered automaticity and suggested that abnormal automaticity was the likely tachycardia mechanism. Intravenous amiodarone slowed the ventricular tachycardia, but the patient eventually succumbed from rapidly progressive left ventricular failure. Postmortem pathohistologic examination confirmed the diagnosis of acute myocarditis.- - - - - - - - - - ranking = 0.5keywords = cycle (Clic here for more details about this article) |
10/37. Retrograde cycle length alternans during supraventricular tachycardia: an unusual tachycardia mechanism.Cycle length alternans is occasionally seen during supraventricular tachycardia due to oscillations in the antegrade atrioventricular nodal (AVN) refractoriness. However, alternans due to retrograde variation in AVN conduction has not been reported. This report describes the case of a 36-year-old man with atypical AVN reentry tachycardia (AVNRT) whose episodes of tachycardia were characterized by continuous oscillations in retrograde AVN conduction. Ablation at one spot eliminated the tachycardia. Cycle length alternans due to oscillations in retrograde AVN conduction, although rare, can be seen during atypical AVNRT and should be considered.- - - - - - - - - - ranking = 2keywords = cycle (Clic here for more details about this article) |
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