Polymorphous Ventricular Tachycardia and Atrioventricular Block

Nine patients are presented who had polymorphous ventricular tachycardia (PMVT) occurring during atrioventricular (AV) block. There were five men and four women with a mean age of 80 +/- 9 years. Five patients had organic heart disease and the remaining four had primary conduction disease (bundle branch block). AV block was complete in four patients (2:1 in three, and paroxysmal in two). The mean ventricular cycle length (of the AV block rhythm) was 1567 +/- 203 ms. The mean QT interval was 0.64 +/- 0.09 s and the mean QTc was 0.51 +/- 0.06 s. When compared to a similar control group with AV block but without PMVT, the ventricular cycle length was similar but the QT and QTc were significantly longer. PMVT was usually of short duration (eight beats to 12 s) and in seven of these nine patients, frequent premature ventricular beats (PVBs) were recorded at various times from the occurrence of PMVT. This is in contrast to the control patients in whom PVBs were detected in one patient only. In conclusion, patients with AV block who develop PMVT usually have longer QT intervals and have detectable PVBs on routine ECGs, unlike similar patients with AV block but without PMVT. In a patient with AV block, a QT interval above 0.60 s and PVBs on the ECG seem to indicate an increased risk for the development of PMVT.     

A Case of Reversible Ventricular Tachycardia and Complete Atrioventricular Block Associated with Primary Cardiac B-Cell Lymphoma

We report a long-term survival case of primary cardiac lymphoma with reversible ventricular tachycardia (VT) and complete atrioventricular block (C-AVB). A 65-year-old man with VT was treated by oral amiodarone administration. Later, a dual-chamber pacemaker was implanted because of C-AVB. Then, he was readmitted, as he complained of fever and chest pain. Echocardiography showed an enlarged cardiac mass and thus an open-chest biopsy was performed. He was then diagnosed with primary cardiac lymphoma. The chemotherapy and radiotherapy resulted in the disappearance of the mass. Complete remission has been maintained for 8 years after the therapy, and no VT or C-AVB has been detected.     

Ablation of Polymorphic Ventricular Tachycardias in Patients with Structural Heart Disease

Background and Objectives: Monomorphic ventricular premature beats (VPB) originating from the Purkinje network can induce polymorphic ventricular tachycardia (PMVT) and ventricular fibrillation (VF) storm. We hereby report the results of targeted ablation to treat PMVT/VF storms initiated by monomorphic VPB in seven patients with structural heart disease and left ventricular (LV)‐dysfunction (n = 4 with coronary artery disease (CAD), n = 2 with chronic and remote myocarditis, n = 1 after aortic valve replacement). Methods and Results: Pace‐mapping and activation mapping was used to identify optimal ablation targets. Earliest activation during mapping was found midseptal of LV in three patients, midinferoseptal of LV in two patients. One patient with myocarditis showed earliest activation at free wall of right ventricle, the other one basal midseptal of LV. Local ventricular electrograms at the successful ablation sites were preceded by short, high frequency, low amplitude potentials by 22–90 ms (median 35 ms). The same local potentials were seen in sinus rhythm. Cycle lengths of VT ranged between 200 and 360 ms (median 245 ms). A median of nine radiofrequency (RF)‐ablations (range 3–19) were necessary to abolish all local Purkinje potentials at the site of earliest activation. Two patients with CAD died due to refractory heart failure. The other five patients had no recurrence of PMVT and VF during follow up (median 10 months, range 1–27 months). Conclusion: The distal Purkinje network plays an important role in triggering PMVT/VF in patients with structural heart disease. Ablation of the triggering VPB originating from the Purkinje arborization is feasible; prevents recurrence in a long‐term follow up; and is potentially life saving in patients with severe LV‐dysfunction after myocardial infarction, in patients after aortic valve replacement, or in patients with myocarditis particularly when medical treatment, including antiarrhythmic drugs, failed to suppress electrical storms.     

Comparison Between Patients with and without Reliahle Ventricular Escape Rhythm in the Presence of Long Standing Complete Atrioventricular Block

The underlying heart rhythm was evaluated in 74 patients with complete atrioventricular block and had a permanent pacemaker implantation. The pacing was inhibited for 10 seconds or until the patient developed symptoms of presyncope or syncope. Fifty-six patients (74%) had a reliable escape with a mean cycle length of 2010 ± 596 msec and a mean escape interval of 2335 ± 971 msec. In 93% of these piatients the escape interval was < 4 seconds. The patients without reliable escape (24%), developed symptoms only after a mean of 7153 ± 1875 msec. The duration of the conduction disorder was longer in the patients without escape and the intraventricular conduction was slower. More patients without escape were treated with antiarrhythmic agents. Forty-eight patients were followed for 1 year and underwent at least two different studies and 13% had different results at different tests. In conclusion, patients without reliable escape have a longer history of conduction disorder, a slower intraventricular conduction, and are frequently treated with antiarrhythmic agents. Even patients with reliable escape occasionally may show a greater pacemaker dependence; therefore, they should also be considered as pacemaker dependent.     

Sinus Rhythm Mapping in a Canine Model of Ventricular Tachycardia

The relationship between electrograms recorded during sinus rhythm and the activation sequence during ventricular tachycardia induced by programmed stimulation was investigated in a canine model of myocardial infarction. Thirteen dogs were studied 3 days (n = 10) or 14 days (n = 3) after coronary occlusion. Sixty-three unipolar electrograms were simultaneously recorded with a sock electrode array connected to a digital recording system, and analyzed by computer. Bipolar electrograms were recorded sequentially from the same sites with an analog recorder. Categories of unipolar electrograms were defined with reference to the QRS complex during sinus rhythm as follows: Class A included electrograms with an intrinsic deflection inscribed within the QRS complex, class B included those which did not exhibit any intrinsic rs deflection, and class C included those with an intrinsic deflection inscribed later than QRS. The epicardial distribution of each class of electrograms was significantly different between the preparations with, and those without inducible tachycardia (72% versus 63% of electrograms being in class A, 20% versus 35% in class B, and 8% versus 2% in class C; p less than 0.005). When tachycardia was inducible, class C epicardial electrograms were located in an area extending across the region of infarction, which corresponded to the common reentrant pathway of figure-of-eight patterns mapped during tachycardia. When ventricular tachycardia was not inducible, class B electrograms were recorded all over this region. The morphology of bipolar electrograms had no predictive value in identifying the common reentrant pathway. These results support the view that the inducibility of reentrant tachycardia is dependent upon critically located delayed activity detected during sinus rhythm by unipolar recordings.     

Accelerated Idioventricular Rhythm: A Rare Case of Wide-Complex Dysrhythmia in a Teenager

BackgroundAccelerated idioventricular rhythm (AIVR) is an uncommon and typically benign dysrhythmia with similarities to more malignant forms of ventricular tachycardia (VT). It is often seen in adults after myocardial infarctions, although it also arises in the newborn period, as well as in children with and without congenital heart disease.Case ReportWe describe a presentation of AIVR in an otherwise healthy 13-year-old girl, discovered on arrival to the pediatric emergency department in the setting of post-tonsillectomy bleeding. The case reviews the diagnostic criteria of AIVR, associated symptoms, the pathophysiologic origin of AIVR, and potential treatment strategies.Why Should an Emergency Physician Be Aware of This?Given its morphologic similarities to life-threatening forms of VT, AIVR can be misdiagnosed in the emergency department or primary care settings. With an understanding of the dysrhythmia's unique features, emergency physicians can avoid unnecessary interventions and provide the correct diagnosis, workup, and management of AIVR for pediatric patients.     

The Effect of Procainamide on Delayed Activation Potentials in a Patient with Ventricular Tachycardia

In a patient with ventricular tachycardia and previous myocardial infarction, delayed activation potentials were recorded from a region of the posterolateral wall of the left ventricle at electrophysiological study. Procainamide, administered intravenously, initially caused increased delay and later, in higher dosage, second-degree block of the delayed potentials.     

Clinical Experience with a New Software-Based Antitachycardia Pacemaker for Recurrent Supraventricular and Ventricular Tachycardias

The Intermedics Intertach 262-12 tachycardia reversion pulse generator was implanted in 14 patients (six male, eight female, mean age at implantation 45 +/- 16 years) with recurrent symptomatic tachycardias. Six patients had atrioventricular (AV) nodal reentrant tachycardia, three patients had orthodromic tachycardia with Wolff-Parkinson-White syndrome, two had circus movement tachycardia via a concealed bypass tract, two had ventricular tachycardia, one patient had atrial flutter. Mean duration of symptoms before implantation was 8 +/- 4 years and mean number of antiarrhythmic drug trials was 3.5 +/- 1. The primary tachycardia response made consisted of autodecremental pacing in one patient, burst pacing in two patients, and adaptive scanning of the initial delay or burst cycle length in eleven patients. The secondary tachycardia response mode consisted of autodecremental pacing in four patients, burst pacing in three patients and burst scanning in four patients. Tachycardia response was automatic in all but one patient with ventricular tachycardia. During a follow-up period of 30.5 +/- 10.6 months, one patient with ventricular tachycardia died from a nonarrhythmic cause. Reinterventions were necessary due to electrode fracture in one patient and due to pacemaker software defect in another one. Two patients underwent surgical cure of their arrhythmia: one patient with atrial flutter and one patient with AV nodal reentry tachycardia, 24 months and 11 months postpacemaker implantation, respectively. Four patients required digitalis to prevent pacing induced atrial fibrillation. Other proarrhythmic effects were not encountered. The pacemaker proved to be a versatile system with reliable tachycardia detection and termination functions. It provided a valuable adjunctive therapy in these selected patients.     

Exercise‐Induced Atrial and Ventricular Tachycardias in a Patient with Left Ventricular Noncompaction and Normal Ejection Fraction

We report a patient with ventricular and atrial tachycardias reproducibly induced during exercise testing. Atrial tachycardia, but no sustained ventricular tachycardia, was induced during electrophysiological study. Catecholaminergic polymorphic ventricular tachycardia was considered because of normal echocardiogram, family history of sudden death, and polymorphic appearance of some of the nonsustained ventricular tachycardia episodes. However, most episodes of ventricular tachycardia were monomorphic. Cardiac magnetic resonance diagnosed isolated left ventricular noncompaction. (PACE 2011; 34:e94–e97)     

Inadvertent Catheter-Induced Right Bundle Branch Block in a Patient with Preexistent Left Bundle Branch Block and Recurrent Macroreentrant Ventricular Tachycardia

This article describes the inadvertent, catheter-induced induction of right bundle branch block resulting not only in transient complete infra-His heart block but also in temporary interruption of the macroreentry circuit of ventricular tachycardia. A patient with preexistent left bundle branch block and spontaneous ventricular tachycardia based upon the bundle branch reentry mechanism underwent electrophysiological testing for the evaluation of sotalol drug efficacy. In search of an optimal His-bundle recording, the manipulation of a 6 Fr quadripolar catheter caused a right bundle branch block, thus advancing the preexistent left bundle branch block to complete heart block. Retrograde ventriculoatrial conduction remained unaffected. The macroreentrant tachycardia with left bundle branch block configuration was no longer inducible. While the patient continued on unchanged sotalol medication (320 mg/d) he required temporary pacing for 16 hours until the block subsided. A subsequent induction attempt demonstrated initiation of the tachycardia. Finally, guided by invasive testing, the patient successfully received amiodarone therapy (300 mg/d). The patient completed an uneventful follow up of 27 months. No progression of conduction delay was observed. This case suggests that the inadvertent induction of right bundle branch block prevents the initiation of ventricular tachycardias relying on bundle branch reentry. Therefore, missed diagnosis or misinterpretation of antiarrhythmic drug efficacy might occur if there is no electrophysiological reevaluation after right bundle branch recovery.     

Idiopathic Left Ventricular Tachycardia with Block Between Purkinje Potential and Ventricular Myocardium

We performed radiofrequency current catheter ablation in a patient with idiopathic LV. While mapping the inferoapical LV septum during tachycardia, spontaneous termination of tachycardia was observed with block between Purkinje (P) potential and ventricular electrogram (P-V block). The cycle length of the tachycardia was associated with prolongation of P-P interval and P-V interval. P potential recording at this site was earliest and at very low amplitude during tachycardia. The radiofrequency current at this site was successful. These findings indicated that Purkinje fiber was a critical part of the tachycardia circuit. Ablation was successful at a site where both an earliest and low amplitude P potential was recorded during tachycardia, and where P-V block that was induced by catheter manipulation was observed during tachycardia.     

Cardioversion, Defibrillation, and Overdrive Pacing of Ventricular Arrhythmias: The Effect of Moricizine in Dogs with Sustained Monomorphic Ventricular Tachycardia

The purpose of this investigation is to define whether the antiarrhythmic drug moricizine has beneficial or adverse effects on currently used antitachycardia and antifibrillatory devices. These studies were performed in a dog model of sustained monomorphic ventricular tachycardia (VT). In 11 dogs, the left anterior descending artery and all surrounding epicardial collateral feeder vessels were ligated. Defibrillator patches were implanted and the dogs were allowed to recover. After a 7-day recovery period, effective refractory period (ERP), end diastolic threshold (EDT), VT induction, and VT and ventricular fibrillation (VF) termination data were collected before and after moricizine infusion (2 mg/kg). In this experimental model, moricizine caused the folIowing electrophysiological changes: a prolongation of the ERP from 173 ± 14 to 182 ± 15 fP < 0.02) with no significant effect on the EDT for pacing; a prolongation of the VT cycle length from 175 ± 18 to 201 ± 23 msec (P < 0.003); an increased cycle length required for overdrive pacing from 136 ± 20 to 157 ± 22 msec (P < 0.01); no effect on the energy required to cardiovert VT; an increase in the defibrillation threshold from 7.5 ±4 to 9.4 ± 4 joules (P < 0.006) and; in 5 of the 8 dogs with VT, theVT could be initiated with somewhat less aggressive stimulation. Significant beneficial electrophysiological effects were noted on theVT cycle length, including a proportionately prolonged overdrive pacing cycle length for VT termination. These changes were contrasted by the significant increase in the VF conversion energy required and the ease with which the VT could be induced postmoricizine. These findings suggest a possible proarrhythmic effect of moricizine.     

Ventricular Fibrillation After Intravenous Atropine in a Patient with Atrioventricular Block

A 69-year-old black woman with complete AV block developed ventricular fibrillation following an IV injection of 1 mg of atropine sulphate. After a successful DC countershock, the ECG showed a polymorphous ventricular tachycardia which subsided spontaneously. Cardiac catheterization revealed a small left ventricular diverticulum and normal coronary arteries. This seems to be the first reported case of atropine-induced ventricular fibrillation in a patient with complete AV block. The fact that this occurred without previous change of the ventricular rate suggests that the adverse action of atropine was mediated through a mere vagolytic effect at the ventricular level.     

Radiofrequency Catheter Ablation of Idiopathic Recurrent Ventricular Tachycardia with Right Bundle Branch Block, Left Axis Morphology

Idiopathic ventricular tachycardia with right bundle branch block and left axis deviation morphology is a well described clinical syndrome. Previous sludies have mapped the tachycordia focus to the inferior septal region at the base of the posterior papillary muscle of the left ventricle. We describe two typical cases in a 20-year' old man and 29-year-old woman in which the tachycardia focus was localized with endocardial mapping techniques. In both cases the ventricular tachycardia focus was ablated with application of radiofrequency current at the inferior septal region. There were no complications of the procedures. The patients remain asymptomatic over follow-up of 7 and 4 months, respectively.     

Analysis during Sinus Rhythm and Ventricular Pacing of Reentry Circuit Isthmus Sites in Right Ventricular Cardiomyopathy

Background: The entrainment mapping algorithm is used for ablation of ventricular tachycardia (VT) in right ventricular (RV) cardiomyopathy, but ablation at endocardial isthmus sites has only a moderate success rate. This study was performed to identify additional local electrogram characteristics associated with successful ablation. Patients and Methods: Using entrainment mapping, 45 reentry circuit isthmus sites were detected in 11 patients with RV cardiomyopathy presenting with 13 monomorphic VTs. Local bipolar electrograms were retrospectively analyzed at reentry circuit isthmus sites during VT, sinus rhythm, and programmed stimulation from the right ventricular apex (RVA), and compared between successful and unsuccessful ablation sites. Results: Ablation was successful at 10 reentry circuit isthmus sites and unsuccessful at 35 isthmus sites. During VT, a longer endocardial activation time relative to QRS onset, an increased electrogram‐QRS interval as a percentage of VT cycle length, and a longer electrogram duration were found at successful in comparison to unsuccessful ablation sites. The presence of isolated diastolic potentials during sinus rhythm at reentry circuit isthmus sites, consistent with slow conduction or unidirectional conduction block, was associated with successful catheter ablation. Prolongation of the duration of the local multipotential electrogram by >100 ms during programmed RVA pacing at reentry circuit exit sites, indicating functional conduction disorder was also a marker of successful ablation. Conclusions: The demonstration of multipotential electrogram characteristics indicating fixed or functional conduction block may increase the likelihood of successful VT ablation at exit and central isthmus sites of reentry circuits in RV cardiomyopathy.     

Successful Radiofrequency Catheter Ablation for Macroreentrant Ventricular Tachycardias in a Patient with Tetralogy of Fallot After Corrective Surgery

CHINUSHI, M., et al .: Successful Radiofrequency Catheter Ablation for Macroreentrant Ventricular Tachycardias in a Patient with Tetralogy of Fallot After Corrective Surgery . Radiofrequency (RF) catheter ablation was applied to two macroreentrant ventricular tachycardias (VTs) documented after corrective operation for tetralogy of Fallot. The activation wavefront of VT with a right bundle branch block pattern was found to revolve in a clockwise manner around a presumed myotomy scar in the right ventricle, and VT with a left bundle branch block pattern revolved around the same anatomical obstacle in a counterclockwise manner. In both VTs, the biggest conduction delay was confirmed at the right ventricular outflow tract. RF applications to the slow conduction area terminated each VT within a few seconds but were insufficient to cure the VTs. RF lesions were then applied to the, slow conduction area in a line to intersect the macroreentrant circuit, and both VTs became noninducible.     

A Case with Catecholaminergic Polymorphic Ventricular Tachycardia Unmasked after Successful Ablation of Atrial Tachycardias from Pulmonary Veins

Catecholaminergic polymorphic ventricular tachycardia (VT) is characterized by polymorphic VT during exercise, and the association of atrial fibrillation (AF) has been reported. However, the mechanism of AF in this disease and the relationship between VT and AF has been obscured. We described a 13-year-old girl who referred for catheter ablation of exercise-induced paroxysmal AF. Multifocal atrial tachycardia mimicking AF on the surface electrocardiogram originated from multiple pulmonary veins (PVs). While AT became non-inducible after the isolation of four PVs, polymorphic VT was initiated by isoproterenol infusion. Polymorphic VT was suppressed during rapid atrial pacing.