Vagal reflex provoked by radiofrequency catheter ablation in the right aortic sinus cusp: a Bezold-Jarisch-like phenomenon

A 66-year-old woman with idiopathic premature ventricular contractions with a left bundle branch block QRS morphology and left inferior axis underwent electrophysiologic testing. Successful radiofrequency ablation was achieved in the right coronary cusp (RCC). However, radiofrequency ablation at sites adjacent to the successful ablation site provoked sinus bradycardia followed by atrioventricular conduction block. That phenomenon might be explained by a vagal reflex through stimulation of vagal pathways or receptors in the anterior epicardial fat pads neighboring to the RCC. A vagal reflex should be kept in mind as a complication during catheter ablation of ventricular arrhythmias originating from the RCC.

QRS alternans with 2:1 atrioventricular conduction block: what is the mechanism?

An 81-year-old woman was admitted for symptomatic bradycardia. On admission, the ECG exhibited QRS alternans, narrow QRS complex and left bundle branch block with 2:1 AV block. The patient soon had complete AV block and underwent a pacemaker implantation. An appropriate mechanism for explaining those ECG findings might be 4:1 conduction over the left bundle branch and 2:1 conduction over the right bundle branch. An ECG pattern exhibiting QRS alternans with a narrow QRS complex and bundle branch block with 2:1 AV block may suggest the coexistence of both bundle branch blocks and a high risk of complete AV block.

Atrial tachycardia with widely-split P waves may mimic a distinct faster atrial tachycardia with half the cycle length of the actual P-P interval

A 57-year-old man with atrial tachycardia (AT) after cavo-tricuspid isthmus ablation underwent electrophysiological testing. Mapping revealed atrial activation with a cycle length exactly twice that of the P-P interval on electrocardiogram. Electroanatomic mapping revealed an AT focus near the left superior pulmonary vein, with inter-atrial conduction occurring in the lower septum and cavo-tricuspid isthmus conduction block. A propagation map demonstrated activation going down the left atrial posterior wall and right atrial free wall, generating different positive P waves in the inferior leads. The focal AT with inter- and intra-atrial conduction block exhibited widely-split P waves misinterpreted as a distinct AT.

Successful radiofrequency catheter ablation of ventricular tachycardia originating from underneath the mechanical prosthetic aortic valve

A 67-year-old man who developed sustained ventricular tachycardia (VT) 4 years after a prosthetic aortic valve replacement, underwent electrophysiologic testing and catheter ablation. The mechanism of the VT was suggested to be triggered activity because the VT could be induced by programmed ventricular stimulation, and burst ventricular pacing demonstrated overdrive suppression without a transient entrainment. Successful catheter ablation using a transseptal approach was achieved underneath the mechanical prosthetic aortic valve on the blind side for that approach. This case demonstrated that catheter mapping and ablation of the entire LV using a transseptal approach might be possible.

Ventricular Tachycardia Originating From the Posterior Papillary Muscle in the Left Ventricle

Background— Several distinct forms of focal ventricular tachycardia (VT) from the left ventricle (LV) have been described. We report a new syndrome of VT arising from the base of the posterior papillary muscle in the LV.

Methods and Results— Among 290 consecutive patients who underwent ablation for VT or symptomatic premature ventricular complexes (PVCs) based on a focal mechanism, 7 patients were found to have an ablation site at the base of the posterior papillary muscle in the LV. All patients had normal LV systolic function and a normal baseline electrocardiogram. The electrocardiogram during VT or PVCs demonstrated a right bundle-branch block and superior-axis QRS morphology in all patients. VT was not inducible by programmed atrial or ventricular stimulation. In 2 patients with sustained VT, overdrive pacing neither terminated VT nor demonstrated any criterion for transient entrainment. Activation mapping localized the earliest site of activation to the base of the posterior papillary muscle in all patients. When Purkinje potentials were recorded at the site of successful ablation, these potentials preceded local ventricular muscle potentials during sinus rhythm. During VT or PVCs, however, the ventricular muscle potential always preceded the Purkinje potentials. After recurrence of VT or PVCs with standard radiofrequency ablation, irrigated ablation was successful in eliminating the arrhythmia in all patients. Over a mean follow-up period of 9 months, all patients have been free of PVCs and VT.

Conclusion— We present a distinct syndrome of VT arising from the base of the posterior papillary muscle in the LV by a nonreentrant mechanism. Ablation can be challenging, and irrigated ablation may be necessary for long-term success.

Multiple macroreentrant ventricular tachycardias exhibiting centrifugal endocardial activations from the scar border zone after myocardial infarction

A 53-year-old man with a ventricular tachycardia (VT) electrical storm during the chronic phase of an extensive anteroseptal myocardial infarction underwent electrophysiologic testing and catheter ablation. An electroanatomical map during 7 induced macroreentrant VTs demonstrated multiple centrifugal endocardial activations from sites that were located at the circumferential border zone of a large scar area. Interestingly, during the radiofrequency catheter ablation of 4 of the VTs, the elimination of the substrate of the previous VTs converted one VT to another probably because those VTs might have shared a central common pathway of the macroreentrant circuit with different exits.

Adenosine can improve the intra-atrial conduction block along the mitral annulus during accessory pathway ablation

A 10-year-old boy with a supraventricular tachycardia was referred for catheter ablation. An electrophysiologic study revealed a left lateral concealed accessory pathway (AP). A few radiofrequency (RF) applications targeting the AP resulted in an inadvertent intra-atrial conduction block at the mitral isthmus without any damage to the AP. Adenosine was then administered during left ventricular pacing. Soon after that, the conduction at the mitral isthmus recovered partially, and that change disappeared soon. Those findings suggested that the administration of adenosine may transiently recover the conduction at the mitral isthmus damaged by RF ablation.

Catheter ablation of focal triggers and drivers of atrial fibrillation

It has been demonstrated that most paroxysmal atrial fibrillation (AF) is triggered by ectopic beats originating from the pulmonary veins (PVs). It has been recently reported that some AF episodes are maintained by focal drivers and AF substrates in the PVs and atrium. Left atrial ablation combined with PV isolation targeting AF triggers and drivers may be effective for eliminating atrial arrhythmias. However, multiple AF drivers in the PVs and atrium and acute conduction recovery after the PV isolation may sometimes render that technique less reliable. In this article, we describe the current status of the catheter ablation of focal triggers and drivers of AF in the PVs and atrium, illustrating with case presentations.

Ventricular tachycardia with an outflow tract septal origin after repair of double outlet right ventricle

A 12-year-old boy born with double outlet right ventricle (RV) developed sustained ventricular tachycardia (VT) 6 years after the corrective surgery and underwent electrophysiologic testing and catheter ablation. Electroanatomic mapping of the right and left ventricles during the VT revealed a centrifugal activation from the outflow tract septum. Though an excellent pace map was obtained in the RV, successful ablation was achieved on the left side. These findings suggested that the VT origin might have been located in the intramural region of the ventricular outflow tract septum with a preferential breakout site in the RV outflow tract.

Intrinsic pulmonary vein automaticity with continuous bigeminal depolarizations after pulmonary vein isolation

A 70-year-old man with atrial fibrillation underwent pulmonary vein (PV) isolation (PVI). Bigeminal concealed PV depolarizations persisted within the right superior PV throughout the PVI. Though the PV depolarizations was suppressed after successful PVI, PV depolarization, following a slow intrinsic PV automatic rhythm, was observed. The coupling interval of the PV depolarizations during the PV automaticity was identical to that of the PV depolarizations during sinus rhythm before the PVI. This case demonstrated that PV depolarization does not always depend on an intact left atrial input, but may depend on some types of triggering electrical activity.

Premature ventricular contractions with a right bundle branch block and inferior QRS axis morphology: where is the site of the origin?

A 63-year-old woman with symptomatic premature ventricular contractions (PVCs) underwent electrophysiologic testing. The PVCs were suggested to originate from the infra-aortic valvular left ventricular outflow tract because the PVCs had S-waves in leads I, V5, and V6, and an R/S ratio >1 in lead V(1). However, during some PVCs without S-waves, the ST segment had negative retrograde P-waves with a longer ventricularatrial (VA) interval. A Radiofrequency (RF) application in the left coronary cusp completely eliminated the PVCs, suggesting that negative retrograde P-waves might have been observed as pseudo S-waves during the PVCs.