Catheter ablation of ventricular tachycardia originating from the left posterior papillary muscle guided by the shadow of a multipolar catheter

A 62-year-old man without structural heart disease underwent electrophysiological testing for ventricular tachycardia (VT). Hemodynamically unstable VT was induced after isoproterenol (ISP) provocation. Electroanatomical mapping using a multipolar catheter identified the earliest activation originating from the posterior papillary muscle (PPM) where prepotentials preceding the local ventricular electrogram were observed. Irrigated radiofrequency current guided by the shadow of a multipolar catheter eliminated the VT. This case suggested that multipolar catheters may be helpful for identifying tachycardia origins arising from the PPM.     

Catheter ablation of fascicular ventricular tachycardia

Fascicular ventricular tachycardia (VT) is an idiopathic VT with right bundle branch block morphology and left-axis deviation occuring predominantly in young males. Fascicular tachycardia has been classified into three subtypes namely, left posterior fascicular VT, left anterior fascicular VT and upper septal fascicular VT. The mechanism of this tachycardia is believed to be localized reentry close to the fascicle of the left bundle branch. The reentrant circuit is composed of a verapamil sensitive zone, activated antegradely during tachycardia and the fast conduction Purkinje fibers activated retrogradely during tachycardia recorded as the pre Purkinje and the Purkinje potentials respectively. Catheter ablation is the preferred choice of therapy in patients with fascicular VT. Ablation is carried out during tachycardia, using conventional mapping techniques in majority of the patients, while three dimensional mapping and sinus rhythm ablation is reserved for patients with nonmappable tachycardia.     

QRS alternans during right ventricular pacing while ablating a concealed left sided accessory pathway

A 16-year-old boy was referred for an electrophysiological study for documented regular narrow complex tachycardia. A diagnosis of a concealed left lateral accessory pathway was made with an eccentric atrial activation sequence both during tachycardia and right ventricular (RV) pacing. The pathway was mapped at the left posterior mitral vestibule during RV pacing, performed through the distal tip of the His bundle catheter pushed into right ventricular outflow tract. An unusual response to ventricular stimulation with alternation of QRS complex width and morphology was noted. The possible mechanisms are hereby discussed.     

Arrhythmogenicity of radiofrequency ablation: Symptomatic non-sustained ventricular tachycardia and frequent premature ventricular ectopics after accessory pathway ablation

Radiofrequency ablation (RFA) has emerged as the preferred treatment modality with high success rate in cases with WPW syndrome. Arrhythmogenic complications are rarely reported after RFA, except for early or late recurrence of accessory pathway (AP) conduction. We present a unique case where the AP was successfully ablated, however, a new monomorphic PVC of similar morphology to the pre-excited beats developed within 30 min of RFA. She required medical management with sotalol to overcome her worsening symptom on follow-up. The ectopics resolved after 4 months.     

Ventricular tachycardia in repaired double chambered right ventricle - identification of the substrate and successful ablation

A 35 year old female presented with recurrent ventricular tachycardia 5 years after she had undergone surgical repair of double chambered right ventricle. Electroanatomical mapping showed a localised scar in the apex with double potentials and good pace map. Ablation here resulted in non-inducibility of ventricular tachycardia. We hypothesise that the scarring in the apex is the result of sustained pressure overload and becomes arrhythmogenic similar to the apical scar in patients with mid-ventricular hypertrophic cardiomyopathy.     

Catheter ablation of recurrent polymorphic tachycardia: Use of sodium channel blockade to organize the tachycardia: A case report

A 55 year old male presented with recurrent implantable cardioverter defibrillator (ICD) shocks due to polymorphic ventricular tachycardia (PMVT). He had undergone prior catheter ablation for VT three years ago. During the prior attempt he underwent voltage guided substrate ablation. With programmed ventricular extrastimulation (PVES), PMVT was repeatedly induced requiring DC shock. Intravenous procainamide was administered and PVES was repeated which induced sustained monomorphic ventricular tachycardia (MMVT). This VT had pseudo delta waves with maximum deflection index of 0.68, suggestive of epicardial origin. Activation mapping was performed epicardially. Presystolic potentials were recorded in mid anterolateral wall of left ventricular epicardial region. Radiofrequency (RF) ablation at this site terminated the VT. Post ablation there was no inducible tachycardia and patient is free of arrhythmias during 2 years of follow-up.     

The first human experience of a contact force sensing catheter for epicardial ablation of ventricular tachycardia

Contact force (CF) is one of the major determinants for sufficient lesion formation. CF-guided procedures are associated with enhanced lesion formation and procedural success. We report our initial experience in epicardial ventricular tachycardia (VT) ablation with a force-sensing catheter using a new approach with an angioplasty balloon. Two patients with arrhythmogenic right ventricular cardiomyopathy who underwent prior unsuccessful endocardial ablation were treated with epicardial VT ablation. CF data were used to titrate force, power and ablation time.     

A case of successful radiofrequency catheter ablation for atrial tachycardia originating from the inferior vena cava using high-resolution mapping

A 60-year-old man presented with sustained supraventricular tachycardia. Atrial tachycardia (AT), with the earliest atrial activation (EAA) occurring at the ostium of the coronary sinus, was reproducibly induced.Three-dimensional electroanatomical mapping (3DEAM) using a 3.5-mm distal electrode tip linear catheter (Thermocool) and radiofrequency energy (RF) was performed at the fractionated atrial electrogram site. It preceded at 30 ms to the EAA but did not terminate AT. Further 3DEAM using a multielectrode mapping catheter (Pentaray) demonstrated a centrifugal propagation pattern at the boundary zone between the right atrium and inferior vena cava. RF application here terminated AT, which then became non-inducible.     

Assessment of ablation catheter contact on valve annulus: Implications on accessory pathway ablation

BackgroundCatheter-tissue contact force is an important factor influencing lesion size and efficacy and thereby potential for arrhythmia recurrence following accessory pathway (AP) radiofrequency ablation. We aim to evaluate adequacy and perception of catheter contact on the tricuspid and mitral annuli.MethodsData were collected from 42 patients undergoing catheter ablation. Operators were blinded to contact force information and reported perceived contact (poor, moderate, or good) while positioning the catheter at four tricuspid annular sites (12, 9, 6 and 4 o'clock positions; abbreviated as TA12, TA9, TA6 and TA4) and three mitral annular sites (3, 5 and 7 o'clock positions; abbreviated as MA3, MA5 and MA7) through long vascular sheaths.ResultsThe highest and lowest mean contact forces were obtained at MA7 (13.3 ± 1.7 g) and TA12 (3.6 g ± 1.3 g) respectively. Mean contact force on tricuspid annulus (6.1 g ± 0.9 g) was lower than mitral annulus (9.8 ± 0.9 g) locations (p = 0.0036), with greater proportion of sites with <10 g contact force (81.7% vs 60.4%; p = 0.0075). Perceived contact had no impact on measured mean contact force for both mitral and tricuspid annular positions (p = 0.959 and 0.671 respectively). There was correlation of both impedance and atrial electrogram amplitude with contact force, though insufficient to be clinically applicable.ConclusionA high proportion of annular catheter applications have low contact force despite being performed with long vascular sheaths in the hands of experienced operators. In addition, there was no impact of operator perceived contact force on actual measured contact force. This may carry implications for success of AP ablation.     

Radiofrequency ablation of a middle cardiac vein inserted accessory pathway resulting in posterolateral coronary artery occlusion: A case report

Introduction

Posteroseptal accessory pathways account for 34.5% of the total. Of these, 36% are located within the coronary sinus (CS). Its ablation requires technical alternatives to avoid damage to surrounding tissues, especially branches of the right coronary artery.

Intra-septal radiofrequency ablation within the transseptal puncture hole targeting an interatrial connection during a bi-atrial tachycardia

A 74-year-old man after multiple mitral valve surgeries underwent catheter ablation of a bi-atrial tachycardia (BiAT). Ultra-high resolution activation mapping exhibited a reentrant circuit propagating around the inferior to anterior mitral annulus and right atrial (RA) septum with two interatrial connections. At the transeptal puncture site, continuous fractionated electrograms were recorded during the BiAT, and entrainment pacing revealed a post-pacing interval similar to the tachycardia cycle length, which suggested that the interatrial conduction from the RA to the left atrium (LA) was located just at the transseptal puncture site. A radiofrequency application inside the transseptal puncture hole could successfully eliminate the BiAT. The ablation target for BiATs propagating around the mitral annulus and RA septum is generally the anatomical mitral isthmus (MI). Since the present case had multiple incisions on both the RA and LA septum due to mitral valve surgeries, there was the possibility of the occurrence of a BiAT including the RA and LA septum after performing an MI linear ablation. Therefore, the preferable ablation target for the BiAT in the present case appeared to be the interatrial connection. Ultra-high resolution detailed mapping not only on the atrial endocardium but also in the transseptal puncture hole may be useful for identifying a critical interatrial connection of BiAT circuits.     

A confluent non-enhanced dark core on serial late gadolinium enhancement imaging after a moderator band-ventricular tachycardia ablation

A 77-year-old man underwent radiofrequency catheter ablation of incessant ventricular arrhythmias (VAs) originating from the right ventricular (RV) moderator band (MB). Activation mapping during the VAs exhibited a centrifugal pattern with the earliest activation site (EAS) on the RV septum. A local impedance (LI)-guided radiofrequency application targeting the EAS with a maximum power output of 50W successfully eliminated the VAs and resulted in an LI drop of up to 35 Ω. Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) on the day after the ablation procedure demonstrated a confluent non-enhanced dark core on the RV septal portion of the MB. On the LGE-MRI two months after the procedure, the dark core region became contracted and instead the peripheral region surrounding the dark core exhibited a bright enhancement. The size of the dark core and peripheral enhanced regions on the LGE-MRI remained almost unchanged two months to two years after the procedure. He had no VA recurrences during a two-year follow-up period. Previous LGE-MRI studies reported that an ablated area within healthy ventricular myocardium exhibits a bright homogenous enhancement during the post-ablation chronic phase, while that within ventricular scar tissue exhibits a confluent non-enhanced dark core. This case suggested the presence of a dark core with a peripheral enhancement corresponding to the ablated area within the healthy myocardium of the RV-MB. LGE-MRI may be useful for accurately detecting RF ablation lesions on the RV-MB and visualizing the serial changes in the LGE-MRI characteristics from the post-ablation acute to chronic phases.     

Detection of oesophageal course during left atrial catheter ablation

BackgroundOesophageal changes and injuries were recorded after atrial fibrillation(AF) ablation procedures. The reduction of power in the posterior left atrial(LA) wall(closest to the oesophagus) and the monitoring of temperature in the oesophagus(OE) reduced oesophageal injuries. The intracardiac-echocardiography(ICE) with a Cartosound module provides two-dimensional imaging (2D) to assess detailed cardiac anatomy and its relationship with the OE. The aim of this study was to highlight the safety and feasibility of 3D-reconstruction of the oesophageal course in left atrial catheter ablation(CA) procedures without OE temperature probe or quadripolar catheter to guide ICE OE reconstruction.Methods180 patients(PT) underwent left atrial ablation. AF ablation were 125(69.5%); incisional left atrial tachycardias(IAFL) were 37(20.6%); left atrial tachycardias(LAT) were 19(10.6%). The LA and pulmonary vein anatomies were rendered by traditional electroanatomic mapping(EAM) and merged with an ICE anatomic map. In 109 PT ICE imaging was used to create a geometry of the OE(group A). A quadripolar catheter was used in 71 PT to show OE course associated to ICE(group B).ResultsAblation energy delivery was performed outside the broadest OE anatomy borders. The duration of procedures was longer in group B vs group A Fluoroscopy time was lower in Group A than Group B(Group A 7 ± 3.2 vs 19.2 ± 2.4 min; p < 0.01).ConclusionsOE monitoring with ICE is safe and feasible. Oesophageal anatomy is complex and variable. Many PT will have a broad oesophageal boundary, which increases the risk of untoward thermal injury during posterior LA ablation. ICE with 3D construction of the OE enhances border detection of the OE, and as such, should decrease the risk of oesophageal injury by improving avoidance strategies without intra-oesophageal catheter visualization.     

Ventricular tachycardia based on cardiac sarcoidosis with a narrow QRS complex,ablated on the left ventricle free-wall

A septuagenarian female with cardiac sarcoidosis suffered from drug refractory ventricular tachycardia (VT) requiring multiple implantable cardioverter-defibrillator shocks. The QRS complex during the VT was very similar to that during sinus rhythm although the QRS width during the VT (142 ms) was relatively wider than that during sinus rhythm (107 ms). The VT exit was located on the ventricular septum close to the His-bundle recording region. However, the critical pathway of this VT was detected on the anterior free wall of the left ventricle (LV), and a radiofrequency application at that site could terminate the VT. No Purkinje potentials were recorded there during the VT or sinus rhythm. According to the electrophysiological study, 3-D mapping, and the response to the ablation, the critical circuit of the VT was surrounded by a protected area of scar associated with cardiac sarcoidosis. As a result, the VT circuit was connected to the basal septal area close to the His-Purkinje system as an outer loop of the VT circuit. This unique trajectory of the VT might have caused a similar QRS morphology to that of sinus rhythm, and the relatively narrow QRS complex despite the critical isthmus was located on the anterior free wall of the LV.     

Combination of Hansen Robotic system with cryocatheter in a challenging parahisian accessory pathway ablation

A perceived distinctive feature of cryoablation is the stability (cryoadherence) of the catheter tip during cold temperatures at the desired location, even during tachycardia. We report the case report of a young patient with a parahisian accessory pathway where stability of the ablation catheter was not achieved despite using the cryocatheter with a steerable sheath. Ultimately, stability at the desired location was achieved robotically by means of Hansen system (Hansen Medical, Mountain View, CA, USA).