Transcoronary venous radiofrequency catheter ablation of ventricular tachycardia

Percutaneous transluminal radiofrequency closure of the coronary artery in animal studies

The aim of this study was to investigate the safety and effectiveness of a novel method for the selective transcoronary closure of small coronary arteries by the intraluminal application of radiofrequency (RF) energy. Twenty-six small (diameter of 1–2 mm) coronary artery branches were selected in 13 dogs. An RF electrode wire (CRW-Zcy) was placed into the target vessel and a coronary balloon was used to transiently block the blood flow and limit damage to the proximal vessel. A therapeutic dosage of 20–30 W of RT energy every 10–30 sec (selected according the diameter of the target artery) was discharged via the CRW-Zcy inside a microcatheter two or three times in order to achieve arterial closure. A high dosage of 60 W every 120 sec of RF energy was used to conduct the safety study. All 26 branches were successfully closed resulting in the complete blockage of the antegrade and retrograde flows. The area of injury was limited to the target artery and the supplied myocardium. High-dose RF did not cause injury to the adjacent vessels and myocardium. The animals tolerated the procedure well without any untoward systemic effects. A follow-up angiography at two weeks revealed no evidence of recanalization or retrograde filling of the target artery. Percutaneous transluminal radiofrequency closure is a safe and effective interventional approach for closing the small coronary arteries, and is potentially valuable for further investigation.

Human coronary venous anatomy: implications for interventions

The coronary venous system is a highly variable network of veins that drain the deoxygenated blood from the myocardium. The system is made up of the greater cardiac system, which carries the majority of the deoxygenated blood to the right atrium, and the smaller cardiac system, which drains the blood directly into the heart chambers. The coronary veins are currently being used for several biomedical applications, including but not limited to cardiac resynchronization therapy, ablation therapy, defibrillation, perfusion therapy, and annuloplasty. Knowledge of the details of the coronary venous anatomy is essential for optimal development and delivery of treatments using this vasculature. This article is part of a JCTR special issue on Cardiac Anatomy.

Prospective versus retrospective ECG-gating for 64-detector computed tomography of the coronary venous system in pigs

BACKGROUND

Multidetector computed tomography (MDCT) provides a non-invasive anatomic description of the coronary veins that may be useful in patients candidates to cardiac resynchronization. Prospective gating reduces radiation exposure but its impact on image quality is unknown is this setting.

AIMS

This study compared image quality and reliability of MDCT angiography of the coronary veins between prospective and retrospective gating.

METHODS

Seven anaesthetized pigs underwent 64-detector row MDCT with prospective and retrospective ECG-gating. MDCT scans were evaluated for visibility of the veins, estimated radiation dose and vein characteristics. Inter- and intra-observer reproducibility was calculated.

RESULTS

Visibility grades of all veins were significantly decreased in prospective (0.82 ± 0.6) compared to retrospective gating (1.68 ± 0.9; P<0.001), the lateral vein being missed in two cases when using prospective vs. retrospective gating. The maximal vein length was significantly increased when using retrospective gating (P=0.015). Inter-observer but not intra-observer reproducibility was dependent on the gating technique for the maximal length and contrast-to-noise ratio (P=0.003 for both). Heart rate was 82 ± 13 bpm and 86 ± 11 bpm during retrospective and prospective ECG-gating (P=ns) despite full dose of atenolol titration.

CONCLUSION

Retrospective gating seems to be superior to prospective gating MDCT to describe the coronary venous system but the conclusions of our study should be confined to high heart rate condition.

The Emerging Role of Epicardial Ablation

Sosa and colleagues first described a percutaneous approach (via the subxiphoid area) to access the pericardial space in 1996. Epicardial mapping and ablation is increasingly used for the treatment of supraventricular and ventricular arrhythmias and represents an adjunctive approach for challenging arrhythmias to improve procedural success rates. Epicardial ablation should be considered not only after the failure of an endocardial ablation but often as a first-line approach. Complications may occur during percutaneous access and epicardial ablation, and these might be reduced or avoided by improved operator skills and experience. New tools to access the epicardial space are being evaluated.

Single-site access robot-assisted epicardial mapping with a snake robot: preparation and first clinical experience

CardioARM, a highly flexible “snakelike” medical robotic system (Medrobotics, Raynham, MA), has been developed to allow physicians to view, access, and perform complex procedures intrapericardially on the beating heart through a single-access port. Transthoracic epicardial catheter mapping and ablation has emerged as a strategy to treat arrhythmias, particularly ventricular arrhythmias, originating from the epicardial surface. The aim of our investigation was to determine whether the CardioARM could be used to diagnose and treat ventricular tachycardia (VT) of epicardial origin. Animal and clinical studies of the CardioARM flexible robot were performed in hybrid surgical–electrophysiology settings. In a porcine model study, single-port pericardial access, navigation, mapping, and ablation were performed in nine animals. The device was then used in a small, single-center feasibility clinical study. Three patients, all with drug-refractory VT and multiple failed endocardial ablation attempts, underwent epicardial mapping with the flexible robot. In all nine animals, navigation, mapping, and ablation were successful without hemodynamic compromise. In the human study, all three patients demonstrated a favorable safety profile, with no major adverse events through a 30-day follow-up. Two cases achieved technical success, in which an electroanatomic map of the epicardial ventricle surface was created; in the third case, blood obscured visualization. These results, although based on a limited number of experimental animals and patients, show promise and suggest that further clinical investigation on the use of the flexible robot in patients requiring epicardial mapping of VT is warranted.

Epicardial Ablation of Idiopathic Ventricular Tachycardia

Epicardial ventricular tachycardia (VT) is an increasingly recognized arrhythmia in clinical practice. Electrocardiographic algorithms to identify epicardial VT should be used with the understanding that they are an initial guide to localization and do not exclude an epicardial origin of VT, particularly when endocardial approaches are unsuccessful. Ablation using a transvenous approach or direct epicardial access may produce favorable results, although care must be taken to avoid coronary artery or phrenic nerve injury. A subset of patients require a combined endocardial and epicardial approach to eliminate VT. Although these ablation strategies are generally well tolerated, they should be limited to patients with highly symptomatic arrhythmias or those in whom myocardial depression is thought to be related to prolonged tachycardia or repetitive ventricular ectopy.

Aneurysm of the great cardiac vein

Anatomical variations in the cardiac veins have the potential to cause iatrogenic injuries during cardiac surgical procedures or cardiac resynchronization therapy. We present a case of an 86-year-old man, which presented with a great cardiac vein aneurysm. The great cardiac vein arose near the apex of the interventricular sulcus to the right of the anterior interventricular branch (AIB) of the left coronary artery and crossed the AIB anteriorly to the left. The great cardiac vein aneurysm appeared to be due to a possible distal constriction of the great cardiac vein by a small muscular branch of the circumflex branch and a possible proximal constriction by the left marginal artery. Cardiologists who interpret imaging of the cardiac veins and cardiac surgeons who operate close to the great cardiac vein should be aware of such a variation.

Improved performance of bayesian solutions for inverse electrocardiography using multiple information sources

The usual goal in inverse electrocardiography (ECG) is to reconstruct cardiac electrical sources from body surface potentials and a mathematical model that relates the sources to the measurements. Due to attenuation and smoothing that occurs in the thorax, the inverse ECG problem is ill-posed and imposition of a priori constraints is needed to combat this ill-posedness. When the problem is posed in terms of reconstructing heart surface potentials, solutions have not yet achieved clinical utility; limitations include the limited availability of good a priori information about the solution and the lack of a "good" error metric. We describe an approach that combines body surface measurements and standard forward models with two additional information sources: statistical prior information about epicardial potential distributions and sparse simultaneous measurements of epicardial potentials made with multielectrode coronary venous catheters. We employ a Bayesian methodology which offers a general way to incorporate these information sources and additionally provides statistical performance analysis tools. In a simulation study, we first compare solutions using one or more of these information sources. Then, we study the effects of varying the number of sparse epicardial potential measurements on reconstruction accuracy. To evaluate accuracy, we used the Bayesian error covariance as well as traditional error metrics such as relative error. Our results show that including even sparsely sampled information from coronary venous catheters can substantially improve the reconstruction of epicardial potential distributions and that a Bayesian framework provides a feasible approach to using this information. Moreover, computing the Bayesian error standard deviations offers a means to indicate confidence in the results even in the absence of validation data.

Ablation of Left Ventricular Epicardial Outflow Tract Tachycardia From the Distal Great Cardiac Vein

OBJECTIVES

The purpose of this study was to examine the feasibility and safety of ablation of idiopathic outflow tract ventricular tachycardia (OTVT) from the distal ramifications of the coronary sinus (CS).

BACKGROUND

A significant minority of patients presenting with idiopathic OTVT have an epicardial focus, the standard approach to which involves ablation from within one of the aortic valve cusps (AVCs). We describe the successful ablation of idiopathic epicardial OTVT from within the CS in the distal great cardiac vein (GCV).

METHODS

Ablation from the distal GCV was performed in 5 patients with idiopathic OTVT who had unfavorable mapping, in some cases unsuccessful ablation from various endocardial and epicardial sites including the AVCs, and in 1 patient via the direct epicardial approach. An electroanatomic mapping system (Carto) was used in 3 patients, and conventional mapping was performed in 2 patients, and in 3 patients cryothermal ablation was performed.

RESULTS

In all patients, the first ablation lesion in the GCV successfully eliminated the arrhythmia. All patients have remained free of VT after a mean follow-up of 24 (7 to 44) months. There were no immediate or long-term complications.

CONCLUSIONS

Idiopathic epicardial OTVT can be successfully ablated from the distal GCV, and should be seen as an alternative to ablation from the aortic valve cusps.

Transcatheter ablation through the cardiac veins in a patient with a biventricular device and left ventricular epicardial arrhythmias

Left ventricular outflow tract (LVOT) may be a source of repeated premature ventricular complexes (PVCs). In symptomatic patients, radiofrequency catheter ablation (RFCA) can be effective, either from endocardial or from epicardial sites. A 50-year-old patient, with dilated cardiomyopathy (DCM) and severe left ventricular (LV) dysfunction, left bundle branch block (LBBB), New York Heart Association (NYHA) class IV, received a biventricular implantable cardioverter/defibrillator (ICD) in 2002. Despite drug therapy, PVCs were frequent (21.019/24 h) including prolonged runs, prompting ICD intervention. Premature ventricular complexes showed an inferior axis morphology, with an R/S ratio in V3>1, suggesting an LVOT origin. Despite the cardiac resynchronization therapy (CRT) device, successful RFCA was performed through the anterior venous branch, with a favourable clinical outcome. To our knowledge, this is the first case describing epicardial RFCA of a PVC focus from cardiac veins in the presence of a CRT device.

Idiopathic Epicardial Left Ventricular Tachycardia Originating Remote From the Sinus of Valsalva

Background— Despite the success of catheter ablation for treatment of idiopathic ventricular tachycardia (VT), occasional patients have been reported in whom VT could not be ablated from the right or left ventricular endocardium or from the aortic sinus of Valsalva (ASOV).

Methods and Results— In 12 of 138 patients (9%) with idiopathic VT referred for ablation, an epicardial left ventricular site of origin was identified >10 mm from the ASOV. Coronary venous mapping demonstrated epicardial preceding endocardial activation by >10 ms (41±7 versus 15±11 ms before QRS onset; P <0.001). VT induction was facilitated by catecholamines and terminated by adenosine. Ablation through the coronary veins or via percutaneous transpericardial catheterization was successful in 9 patients; 2 required direct surgical ablation as a result of anatomic constraints. No ECG pattern was specific for epicardial VT. However, slowed initial precordial QRS activation, as quantified by a novel metric, the maximum deflection index, was more useful. A delayed precordial maximum deflection index ≥0.55 identified epicardial VT remote from the ASOV with a sensitivity of 100% and a specificity of 98.7% relative to all other sites of origin ( P <0.001).

Conclusions— Although clinically underrecognized, idiopathic VT may originate from the perivascular sites on the left ventricular epicardium. The mechanism is consistent with triggered activity. It is amenable to ablation by transvenous or transpericardial approaches, although technical challenges remain. Recognition of a prolonged precordial maximum deflection index and early use of transvenous epicardial mapping are critical to avoid protracted and unsuccessful ablation elsewhere in the ventricles.

Epicardial Ablation With Cooled Tip Catheter Close to the Coronary Arteries is Effective and Safe in the Porcine Heart if the Ventricular Potential is Being Monitored in the Epicardium and Endocardium

BACKGROUND

Transthoracic epicardial ablation can be an alternative to conventional treatment for critical pathways of ventricular tachycardia located in the epicardium. However, the usefulness and safety of epicardial ablation close to the coronary arteries (CA) is not clear. The purpose of the present experimental animal study was to analyze the efficacy and safety of epicardial radiofrequency (RF) ablation close to the CA.

METHODS AND RESULTS

Of the left ventricle-epicardium ablated sites, 35 lesions (20 with cooling and 15 without cooling) were close to the CA (left anterior descending artery < or = 15 mm) and 33 lesions (23 with cooling and 10 without cooling) were further from the CA. For sites close to the CA, epicardial ablation was effective in 77% (15/20) with cooling and in 40% (6/15) without cooling. There was a significant difference of effective ablation between with cooling and without cooling (p < 0.05). For cooling, epicardial lesion size could be predicted by the change of endocardial ventricular potential using a basket catheter. No damage to major epicardial arteries was detected when the catheter tip was positioned 5 mm away from the CA.

CONCLUSIONS

Close to the CA, RF ablation with cooling is more effective than RF without cooling and is safe if the ablation sites are located 5 mm away from the major CA.

Epicardial Idiopathic Ventricular Tachycardia Originating Within the Left Main Coronary Artery Ostium Area: Identification Using the LocaLisa Nonfluoroscopic Catheter Navigation System

Idiopathic ventricular tachycardia (IVT) in patients without structural heart disease commonly arises from the right or left outflow tracts, but there remain arrhythmias that can only be ablated by an epicardial approach. We report a case of an epicardial ventricular tachycardia originating within the left main coronary artery ostium area, as identified using the LocaLisa nonfluoroscopic catheter navigation system. Due to the high risk of coronary artery thrombosis, ventricular tachycardia was successfully ablated by a transthoracic surgical approach using cryoenergy. Ventricular ectopy disappeared and ventricular tachycardia did not recur during long-term follow-up.

Idiopathic Left Ventricular Tachycardia Originating from the Mitral Annulus

BACKGROUND

Radiofrequency catheter ablation (RFCA) can eliminate most idiopathic repetitive monomorphic ventricular tachycardias (RMVTs) originating from the right and left ventricular outflow tracts (RVOT, LVOT). Here, we describe the electrophysiological (EP) findings of a new variant of RMVT originating from the mitral annulus (MAVT).

METHODS AND RESULTS

MAVT was identified in 35 patients out of 72 consecutive left ventricular RMVTs from May 2000 to June 2004. All patients underwent an EP study and RFCA. The sites of origin of the MAVT were grouped into four groups according to the successful ablation sites around the mitral annulus. Group I included the anterior sites (n = 11), group II the anterolateral sites (n = 9), group III the lateral sites (n = 6), and group IV the posterior sites (n = 9). The MAVTs were a wide QRS tachycardia with a delta wave-like beginning of the QRS complex. The transitional zone of the R wave occurred between V1-V2 in all cases. The 12-lead electrocardiogram (ECG) pattern might reflect the site of the origin of MAVTs around the mitral annulus. We proposed an algorithm for predicting the site of the focus and the tactics needed for successful RFCA of the MAVT.

CONCLUSIONS

We described the EP findings of the new variant of RMVT, MAVT. Most MAVTs could be eliminated by RF applications to the endocardial mitral annulus using our proposed tactics.

Longitudinally Partitioned Coronary Sinus: An Unusual Anomaly of the Coronary Venous System

We report a case of a patient with advanced heart failure who had a longitudinally partitioned coronary sinus. With multidirectional fluoroscopic views and a careful approach to the target lumen, a left ventricular lead for biventricular pacing was placed successfully in the left marginal vein.

Idiopathic ventricular arrhythmia arising from the mitral annulus

OBJECTIVES

We sought to clarify the prevalence and characteristics of idiopathic ventricular tachycardia or premature ventricular contraction originating from the mitral annulus (MAVT/PVC).

BACKGROUND

Recent case reports have presented patients with MAVT/PVC.

METHODS

Electrocardiographic (ECG) characteristics and the results of electrophysiologic investigation and radiofrequency catheter ablation (RFCA) were analyzed in 352 patients with symptomatic idiopathic ventricular tachycardia (IVT)/premature ventricular contraction (PVC).

RESULTS

Nineteen cases of IVT/PVC (5%) represented MAVT/PVC. Of these, 11 (58%) originated from the anterolateral portion of the mitral annulus (AL-MAVT/PVC), and 2 (11%) arose from the posterior portion (Pos-MAVT/PVC). The remaining six cases of MAVT/PVC (31%) had posteroseptal origin (PS-MAVT/PVC). In all patients, an S-wave was present in lead V(6). The QRS polarity in inferior leads and leads I and aVL was useful for differentiating AL-MAVT/PVC from Pos-MAVT/PVC or PS-MAVT/PVC. The Pos-MAVT/PVC had an Rs pattern in lead I and an R pattern in lead V(1), whereas PS-MAVT/PVC invariably had an R pattern in lead I and a negative QRS component in lead V(1). The AL-MAVT/PVC and Pos-MAVT/PVC showed a longer QRS duration than the PS-MAVT/PVC (p < 0.001), and all had late-phase "notching" of the QRS complex in inferior leads. In all patients, RFCA eliminated MAVT/PVC, with no recurrences during follow-up for 21 +/- 15 months.

CONCLUSIONS

Mitral annular VT/PVC is a rare but distinct subgroup of IVT/PVC. MAVT/PVC origin could be determined by ECG analysis. The AL and PS sites of the MA were preferential.

Outflow tract tachycardia with R/S transition in lead V3

OBJECTIVES

The aim of this study was to analyze different anatomic mapping approaches for successful ablation of outflow tract tachycardia with R/S transition in lead V(3).

BACKGROUND

Idiopathic ventricular tachycardia can originate from different areas in the outflow tract, including the right and left ventricular endocardium, the epicardium, the pulmonary artery, and the aortic sinus of Valsalva. Although electrocardiographic criteria may be helpful in predicting the area of origin, sometimes the focus is complex to determine, especially when QRS transition in precordial leads is in V(3).

METHODS

We analyzed surface electrocardiograms of 33 successfully ablated patients with outflow tract tachycardia: 20 from the right ventricular outflow tract (RVOT) and 13 from different sites. The R/S transition was determined, and the different anatomic approaches needed for successful catheter ablation were studied.

RESULTS

Overall, R/S transition in lead V(3) was present in 19 (58%) of all patients. In these patients, mapping was started and successfully completed in the RVOT in 11 of 19 (58%) patients. The remaining eight patients with R/S transition in lead V(3) needed five additional anatomic accesses for successful ablation: from the left ventricular outflow tract (n = 3), aortic sinus of Valsalva (n = 2), coronary sinus (n = 1), the epicardium via pericardial puncture (n = 1), and the trunk of the pulmonary artery (n = 1), respectively.

CONCLUSIONS

A R/S transition in lead V(3) is common. In patients with outflow tract tachycardia with R/S transition in lead V(3), a stepwise endocardial and epicardial mapping through up to six anatomic approaches can lead to successful radiofrequency catheter ablation.

Three-Dimensional Visualization of the Coronary Venous System Using Multidetector Row Computed Tomography

BACKGROUND

This study was undertaken to investigate the applicability and image quality of contrast-enhanced visualization of the coronary venous system (CVS) by multidetector row computed tomography (MDCT).

METHODS AND RESULTS

A total of 70 patients underwent MDCT and for each patient, 6 data sets were created throughout the cardiac cycle. The number and location of coronary veins were evaluated in 3-dimensional images using the 6 data sets. The quality of all images reconstructed from the 6 data sets was too poor to evaluate the CVS in 6 patients (9%). In the remaining 64 patients (91%), the diameter of the CVS was usually greater in the images reconstructed from data acquired during systole than in those reconstructed from data acquired during diastole. However, artifacts were observed more often in images from systole than from diastole. The coronary sinus and middle cardiac vein were visible in all 64 patients. The left marginal and posterior veins also were identified in 54 (84%) and 60 patients (94%), respectively.

CONCLUSIONS

MDCT can be used as a non-invasive modality for evaluating the CVS anatomy in most patients.

Simultaneous Mapping in the Left Sinus of Valsalva and Coronary Venous System Predicts Successful Catheter Ablation from the Left Sinus of Valsalva

Idiopathic ventricular tachycardia originating from the left epicardium (Epi-VT) can be ablated from the left sinus of Valsalva (LSV) in selected patients. We hypothesized that the analysis of electrograms at the LSV and transitional zone from the great cardiac vein to the anterior interventricular vein (GCV-AIV) could predict the efficacy of radiofrequency catheter ablation (RFCA) from the LSV. Simultaneous mapping in the LSV and coronary venous system was performed in 25 patients (12 VTs and 13 premature ventricular contractions). The earliest ventricular activation (VA) during the arrhythmias was found at the LSV or GCV-AIV in all patients. RF applications from the LSV were successful in 17 patients success group (S-Gr) and failed in 8 failure group (F-Gr). The earliness of the VA recorded in the LSV (VA[LSV]) and in GCV-AIV (VA[GCV-AIV]) was compared between the two groups. (1) The VA[LSV] preceded the QRS onset by 28 +/- 11 ms in S-Gr and 14 +/- 10 ms in F-Gr (P < 0.01). (2) In S-Gr, the VA[GCV-AIV] was earlier than the VA[LSV] in 5 five patients (35%). However, in F-Gr, the VA[GCV-AIV] was earlier than the VA[LSV] in all patients. (3) In patients in whom the earliest VA was found at the LSV or GCV-AIV, a VA [GCV-AIV] preceding the VA[LSV] by less than 10 ms identified successful RFCA from the LSV with a sensitivity of 88 %, specificity of 100%, and high predictive value. With a detailed analysis of the electrograms recorded from the GCV-AIV and LSV, it was possible to identify the successful catheter ablation of Epi-VT from the LSV.

The coronary sinus: Passive bystander or source of arrhythmia?1 1ASSOCIATE EDITOR: D. GEORGE WYSE

The coronary sinus provides access to the epicardial space of the heart allowing ablation of epicardial accessory pathways, foci of ventricular arrhythmia, and arrhythmogenic areas such as the vein or ligament of Marshall. In addition, its musculature may form atrioventricular accessory connections, participate in macroreentrant atrial arrhythmias, and generate foci of microreentrant atrial tachycardia and fibrillation. Thus, the coronary sinus may serve both as a bystander to arrhythmia circuits as well as an original source of cardiac arrhythmia.

A review of the coronary venous system: a road less travelled

Compared with the coronary arterial system, less attention has been paid to the coronary venous system. In the current era, there are therapeutic options for arrhythmias and for heart failure that use the coronary venous system to access target areas. We review the arrangement of the main cardiac veins to provide a morphologic background to interventionists. In general, the venous system is a useful conduit for delivery of percutaneous transcatheter treatment. But, variability in terms of valves, diameter, angulation, extent of muscular sleeves, proximity to other cardiac structures, and cross-over spatial relationship with branches of coronary arteries have implications for practitioners seeking to make use of the system.

Electrocardiographic Recognition of the Epicardial Origin of Ventricular Tachycardias

BACKGROUND

Some ventricular tachycardias (VTs) originating from the epicardium are not suitable for endocardial radiofrequency ablation and require an epicardial approach. The aim of this study was to define the ECG characteristics that may identify an epicardial origin of VTs.

METHODS AND RESULTS

We analyzed the 12-lead ECG recordings during epicardial and endocardial left ventricular pacing in 9 patients to verify the hypothesis that the epicardial origin of the ventricular activation widens the initial part of the QRS complex. Then, we analyzed the ECG pattern in 14 VTs successfully ablated from the epicardium after a failed endocardial approach (group A), in 27 VTs successfully ablated from the endocardium (group B), and in 28 additional VTs that could not be ablated from the endocardium (group C). Four distinct intervals of ventricular activation were defined and measured: (1) the pseudodelta wave, (2) the intrinsicoid deflection time in V2, (3) the shortest RS complex, and (4) the QRS complex. VTs from groups A and C showed a significantly longer pseudodelta wave, intrinsicoid deflection time, and RS complex duration compared with VTs of group B. There was no difference between groups A and C. A pseudodelta wave of > or =34 ms has a sensitivity of 83% and a specificity of 95%, an intrinsicoid deflection time of > or =85 ms has a sensitivity of 87% and a specificity of 90%, and an RS complex duration of > or =121 ms has a sensitivity of 76% and a specificity of 85% in identifying an epicardial origin of the VTs.

CONCLUSIONS

ECG suggests VTs originating from the epicardium and those with an unsuccessful radiofrequency ablation from the endocardium.

Ventricular Unipolar Potential in Radiofrequency Catheter Ablation of Idiopathic Non-Reentrant Ventricular Outflow Tachycardia

We conducted this study to verify the efficacy of ventricular unipolar potential (V-uni) for ablation of idiopathic non-reentrant ventricular tachycardia (idio-VT). The morphology of V-uni at the successful and unsuccessful sites was analyzed in 27 patients with idio-VT [20 with right ventricular outflow tachycardia (RVOVT) and 7 with left ventricular outflow tachycardia (LVOVT)]. The usefulness of V-uni was compared with a pacemapping method and the V-QRS interval. The incidence of QS-pattern V-uni at the successful and best unsuccessful sites were 100 versus 25% (P = 0.000005) in RVOVT and 86 versus 29% (P = 0.10) in LVOVT. The pacemapping scores at the successful and best unsuccessful sites were 11.5/12 versus 11.2/12; NS in RVOVT, and 11.2/12 versus 11.1/12; NS in LVOVT. The mean V-QRS interval at the successful and the best unsuccessful sites were 22.5 +/- 3.8 versus 21.6 +/- 3.4 msec; NS in RVOVT, 15.1 +/- 3.2 versus 12.5 +/- 3.3 msec; NS in LVOVT. The sensitivity (sen) and specificity (spe) of QS-pattern V-uni to determine the optimum target sites were 1.0 and 0.89 in RVOVT and 0.86 and 0.83 in LVOVT, respectively. In the ablation of idio-VT, QS-pattern V-uni is simply and visually identifiable, is very useful, and should be given a high priority when determining the optimum target site.

Development and Validation of an ECG Algorithm for Identifying the Optimal Ablation Site for Idiopathic Ventricular Outflow Tract Tachycardia

INTRODUCTION

Idiopathic ventricular outflow tract tachycardia or premature ventricular contractions (OT-VTs) can originate from several different sites in the outflow tract, including the left ventricular (LV) endocardium and epicardium. The aims of this study were (1) to develop an ECG algorithm to predict the origin of OT-VT and (2) to test prospectively the accuracy of the algorithm.

METHODS AND RESULTS

An algorithm was developed by correlating the 12-lead ECG findings with the catheter ablation site in 80 patients with OT-VT. The ECG characteristics of the QRS complex during the arrhythmia were analyzed. The catheter sites were verified by multi-plane fluoroscopy. The outflow tract was classified into six subdivisions: right ventricular (RV) septum, RV free wall, RV near the His-bundle region, LV endocardium, left sinus of Valsalva (LSV), and LV epicardium remote from the LSV. An OT-VT originating from the LV epicardium remote from the LSV was defined as an OT-VT in which the earliest ventricular activation was recorded at the LSV and radiofrequency ablation from the LSV failed. This algorithm subsequently was tested prospectively in 88 patients. Overall sensitivity was 88% and specificity was 95%. The positive and negative predictive values were 88% and 96%, respectively.

CONCLUSION

We describe a new ECG algorithm having a high sensitivity and specificity to identify the optimal ablation site for idiopathic ventricular outflow tachycardia or premature ventricular contractions.

Percutaneous pericardial instrumentation for endo-epicardial mapping of previously failed ablations

BACKGROUND

The epicardial location of an arrhythmia could be responsible for unsuccessful endocardial catheter ablation.

METHODS AND RESULTS

In 48 patients referred after prior unsuccessful endocardial ablation, we considered percutaneous, subxiphoid instrumentation of the pericardial space for mapping and ablation. Thirty patients had ventricular tachycardia (VT), 6 patients had a right- and 4 had a left-sided accessory pathway (AP), 4 patients had inappropriate sinus tachycardia, and 4 patients had atrial arrhythmias. Of the 30 VTs, 24 (6 with ischemic cardiomyopathy, 3 with idiopathic cardiomyopathy, and 15 with normal hearts) appeared to originate from the epicardium. Seventeen (71%) of these 24 VTs were successfully ablated with epicardial lesions. The other 7 VTs had early epicardial sites that were inaccessible, predominantly because of interference from the left atrial appendage. Six of these were successfully ablated from the left coronary cusp. In 5 of the 10 patients with an AP, the earliest activation was recorded epicardially. Three of these were right atrial appendage-to-right ventricle APs, and epicardial ablation was successful. No significant complications were observed.

CONCLUSIONS

Failure of endocardial ablation could reflect the presence of an epicardial arrhythmia substrate. Epicardial instrumentation and ablation appeared feasible and safe and provided an alternative strategy for the treatment of patients with a variety of arrhythmias. This was particularly true for VT, including patients without structural heart disease.

Nonsurgical transthoracic epicardial radiofrequency ablation: an alternative in incessant ventricular tachycardia

OBJECTIVES

The purpose of this study was to analyze the feasibility, efficacy, and safety of epicardial radiofrequency (RF) ablation in patients with incessant ventricular tachycardia (VT).

BACKGROUND

Management of patients with incessant VT is a difficult clinical problem. Drugs and RF catheter ablation are not always effective. A nonsurgical transthoracic epicardial RF ablation can be an alternative in patients refractory to conventional therapy.

METHODS

Epicardial RF ablation was performed in 10 patients who presented with incessant VT despite the use of two or more intravenous antiarrhythmic drugs.

RESULTS

In eight patients, endocardial ablation (EdA) failed to control the tachycardia. In the remaining two patients, epicardial ablation (EpA) was first attempted because of left ventricular thrombus and severe artery disease, respectively. Eight patients had a diagnosis of coronary artery disease with healed myocardial infarction. One patient had dilated cardiomyopathy, and one patient had idiopathic, incessant VT. In patients with structural heart disease, the mean ejection fraction was 0.28 +/- 0.10%. Four patients previously received an implantable defibrillator. The EpA effectively terminated the incessant tachycardia in eight patients, which represents a success rate of 80%. In them, after a follow-up of 18 +/- 18 months, a single episode of a different VT was documented in one patient. No significant complications occurred related to the procedure.

CONCLUSIONS

In patients with incessant VT despite the use of drugs or standard EdA, the epicardial approach was very effective and should be considered as an alternative in this life-threatening situation.

Investigation of coronary venous anatomy by retrograde venography in patients with malignant ventricular tachycardia

BACKGROUND

The coronary venous system is increasingly used for left ventricular or biventricular pacing in patients with severe heart failure. The present study investigated the structure of the coronary veins in patients presenting with structural heart disease and malignant ventricular tachyarrhythmias. The availability of veins for possible lead placement was assessed.

METHODS AND RESULTS

The number, relative size, and location of coronary veins were evaluated by retrograde venography in 129 patients undergoing cardioverter-defibrillator implantation. Detailed x-ray image analysis was performed in 86 patients, for whom optimal coronary sinus occlusion and vein visualization was achieved. The anterior interventricular vein and the middle cardiac vein were visible in 85 (99%) of 86 patients and in 86 (100%) of 86 patients, respectively. Between these 2 veins, at least 1 additional prominent vein was visible in 85 (99%) of 86 patients. Just 1 vein was present in 44 (51%) of 86 patients. Two veins were observed in 40 (46%) of 86 patients, and >2 veins were visualized in 2 (2%) of 86 patients. Venous anatomy allowed positioning of a 0.014-in guidewire in a coronary vein in 115 (93%) of 124 patients.

CONCLUSIONS

The presence, diameter, angulation, and tortuosity of veins as visualized by retrograde venography determine their acceptability for the placement of a lead in a predetermined location. Despite the considerable variability of the coronary venous system among patients, a lateral vessel for lead introduction was available in 82%, and a posterior or lateral vessel was available in 99% of individuals within a patient population that could potentially benefit from a lead on the left ventricle.

Clinical characteristics and catheter ablation of left ventricular outflow tract tachycardia

Left ventricular outflow tract (LVOT) tachycardia is an uncommon form of idiopathic ventricular tachycardia (IVT). The underlying mechanism of this arrhythmia appears to be cyclic AMP-medicated triggered activity. The tachycardia occurs in the absence of structural heart disease and is generally benign, presenting commonly as palpitations and presyncope. It can manifest either a right or left bundle branch block morphology with an inferior axis. Subtle variations in the QRS morphology in leads I, V1, and V2 can help in localizing the anatomic site of origin (SOO). The arrhythmia is typically responsive to a variety of pharmacologic agents (beta-blockers, calcium channel blockers, Class I and II agents). Radiofrequency catheter ablation of LVOT tachycardia SOO as determined by pace mapping is quite efficacious (success rates of 90%). Magnetic electroanatomic mapping augments this by permitting three-dimensional catheter mapping and reproducible localization of the SOO. Catheter ablation should be considered relatively early in patients who experience severe symptoms with their arrhythmia and have failed, or are reluctant to take medications for the disorder.

Ventricular tachycardias arising from the aortic sinus of valsalva: an under-recognized variant of left outflow tract ventricular tachycardia

OBJECTIVES

To describe a normal heart left bundle branch block, inferior axis ventricular tachycardia (VT), that could not be ablated from the right or left ventricular outflow tracts.

BACKGROUND

Whether these VTs are epicardial and can be identified by a specific electrocardiographic pattern is unclear.

METHODS

Twelve patients with normal heart left bundle branch block, inferior axis VT and previously failed ablation were included in this study. Together with mapping in the right and left ventricular outflow tracts, we obtained percutaneous epicardial mapping in the first five patients and performed aortic sinus of Valsalva mapping in all patients.

RESULTS

No adequate pace mapping was observed in the right and left ventricular outflow tracts. Earliest ventricular activation was noted in the epicardium and the aortic cusps. All patients were successfully ablated from the aortic sinuses of Valsalva (95% CI 0% to 18%). The electrocardiographic pattern associated with this VT was left bundle branch block, inferior axis and early precordial transition with Rs or R in V2 or V3. Ventricular tachycardia from the left sinus had rS pattern in lead I, and VT from the noncoronary sinus had a notched R wave in lead I. None of the patients had complications and all remained arrhythmia-free at a mean follow-up of 8 +/- 2.6 months.

CONCLUSIONS

Normal heart VT with left bundle branch block, inferior axis and early precordial transition can be ablated in the majority of patients from either the left or the noncoronary aortic sinus of Valsalva.

Management of ventricular tachycardia in patients with clinically normal hearts

The majority of patients who present with ventricular tachycardia have underlying structural heart disease. However, there has been increasing appreciation of the existence of multiple forms of idiopathic ventricular tachycardia with distinct features and unique mechanisms. The most common form of idiopathic ventricular tachycardia originates from the right ventricular outflow tract, is characterized by sensitivity to adenosine, and appears to be due to cyclic AMP-mediated triggered activity. Other forms of idiopathic ventricular tachycardia include intrafascicular left ventricular tachycardia, due to reentry, which is sensitive to verapamil, and automatic, propranolol-sensitive ventricular tachycardia.

Ventricular arrhythmias following thermal damage of epicardial tissue: possible causes and clinical implications

Epicardial heating may be used for ventricular tachycardia (VT) ablation and transmyocardial revascularization. However, the potential risks of thermal epicardial injury, including arrhythmia, have not been fully explored. This study relates the pathologic and arrhythmic sequellae of epicardial heating when applied with a diode laser at varying doses. Acute pathology and dosimetry were determined in a group of normal dogs using 2-3 W over 30-90 seconds. Another group received a similar dose range before undergoing 24-hour monitoring, and electrophysiological testing was done at 4 weeks. In this group, four dogs each received 12 lesions (90-180 J) according to a randomized block design. Another dog received nine lower dose lesions (30-120 J). Acute lesions measured 2.5-8.0-mm wide by 4-8.5-mm deep. Charring and vaporization were common when 3 W were applied over 45 seconds. Within 24 hours, VT with features of abnormal automaticity occurred in all dogs receiving this dose. The dog in whom lower doses induced coagulation only had no VT. Four weeks later, electrophysiological study induced no VT. At this time fibrosis and granulation tissue were organizing the contraction band necrosis seen acutely, and some lesion borders were becoming calcified. No major vessels had been damaged. Abnormal automaticity and VT may occur if thermal damage of the epicardium exceeds coagulation. This could be related to tissue injury caused by sudden water vaporization, and may have clinical relevance given the growing indications for myocardial heating.

Radiofrequency catheter ablation from the left sinus of Valsalva in a patient with idiopathic ventricular tachycardia

We report the case of a 54-year-old woman with idiopathic VT originating in the left ventricular outflow tract. She initially presented with palpitations and light-headedness. The morphology of the PVCs exhibited an inferior axis and tall R waves were noted in all the precordial leads. Spontaneous PVCs were transiently terminated by an intravenous injection of adenosine triphosphate. Radiofrequency catheter ablation from the left sinus of Valsalva successfully abolished the PVCs and the VT.

Successful radiofrequency catheter ablation from the supravalvular region of the aortic valve in a patient with outflow tract ventricular tachycardia

Outflow tract ventricular tachycardia (OT-VT) was successfully ablated from the right coronary cusp of the aortic valve. The 12-lead ECG was totally different from the typical right ventricular OT-VT because the R/S ratio in precordial lead V1 was equal to 1 and tall R waves in precordial leads V2-6 were seen. Radiofrequency energy application from the right coronary cusp of the aortic valve successfully ablated this VT without complications. Radiofrequency catheter ablation from the right coronary cusp of the aortic valve can be done safely and effectively.

Successful treatment of idiopathic left ventricular outflow tract tachycardia by catheter ablation or minimally invasive surgical cryoablation

Idiopathic right ventricular outflow tract tachycardia is readily amenable to radiofrequency catheter ablation. However, treatment modalities for left ventricular outflow tract tachycardia are not well defined. Out of 37 patients with idiopathic outflow tract tachycardia referred for catheter ablation, in 3 patients tachycardia originated from the left ventricular outflow tract. On the surface ECG, all left ventricular tachycardias exhibited an inferior axis with a predominant negative QRS complex in lead I. Heart rate during tachycardia ranged from 115 to 170 beats/min. During electrophysiological testing, 1 patient had inducible tachycardia on orciprenaline challenge, 1 patient had inducible tachycardia at baseline, and 1 patient had incessant tachycardia. In two patients, earliest ventricular activation was recorded from the endocardial left ventricular outflow tract at an anterolateral and an anterior site, respectively. A distinct high frequency spike preceded the QRS onset by 66/78 ms. Application of radiofrequency energy successfully eliminated tachycardia at these sites. In one patient, tachycardia originated from the epicardial left ventricular outflow tract. Mapping of the anterior interventricular vein revealed a fractionated low amplitude signal occurring 46 ms before QRS onset. After failure of catheter ablation from the corresponding endocardial site, successful minimally invasive surgical focal cryoablation of the epicardial target region was performed. During a follow-up period ranging from 7 to 12 months, all patients remained free of tachycardia. In conclusion, ventricular tachycardia arising from the left ventricular outflow tract may require endo- and epicardial mapping. Successful treatment is achieved by radiofrequency catheter ablation or minimally invasive surgical cryoablation.

Ventricular arrhythmias in normal hearts

Idiopathic ventricular tachycardia (VT) is characterized by two predominant forms. The most common form originates from the right ventricular outflow tract and presents as repetitive monomorphic VT or exercise-induced VT. The tachycardia is adenosine sensitive and is thought to be because of cAMP-mediated triggered activity. The other major form of idiopathic VT is owing to verapamil-sensitive intrafascicular re-entrant tachycardia, which most often originates in the region of the left posterior fascicle. Both forms of idiopathic VT can be readily treated with radiofrequency catheter ablation.

Radiofrequency catheter ablation of ventricular tachycardia from the anterobasal left ventricle

Ventricular tachycardia (VT) in coronary artery disease arises mostly from endocardial sites. However, little is known about the site of origin in other diseases. We report two patients who had VT originating from an anterior aspect of the left ventricle just below the mitral annulus, adjacent to the left ventricular outflow tract. The QRS configuration of VT showed an inferior axis and monophasic R waves in all the precordial leads. Radiofrequency current delivered to this site from the endocardial site successfully ablated the tachycardia in both.

Dual morphology of idiopathic ventricular tachycardia

INTRODUCTION

Idiopathic ventricular tachycardia (VT) typically has a single morphology originating either in the right ventricular outflow tract (RVOT) or near the posterior fascicle of the left ventricle (LV) in most instances. We present our observations in six patients with idiopathic VT in whom two morphologies were present.

METHODS AND RESULTS

Of 55 patients with idiopathic VT who underwent radiofrequency (RF) ablation, 44 had LV "fascicular" tachycardia, whereas 11 had RVOT tachycardia. During RF energy delivery, there was a change in VT morphology in two patients with idiopathic LV tachycardia. This second morphology was not ablated initially, recurred at follow-up, and was reablated successfully. In two additional patients with idiopathic LV tachycardia, a second VT was inducible after ablation of the "clinical" VT. This second morphology recurred at follow-up and was ablated successfully in one patient. The site where the second VT was ablated in all the three patients was remote from that of the first VT. In two patients with RVOT tachycardia, a second VT, originating from a different area of the RVOT, was induced after RF ablation of the "clinical" VT. This second VT recurred at follow-up and was reablated successfully in one patient.

CONCLUSION

Idiopathic VT is a more heterogenous entity than hitherto believed. A second VT was seen in 11% of patients during or after RF ablation of the "clinical" VT. The appearance of a second VT suggests either a different exit site of the same circuit or another site of origin.

Successful radiofrequency catheter ablation of incessant ventricular tachycardia with a delta wave-like beginning of the QRS complex

Ventricular tachycardia with a delta wave-like beginning of the QRS complex is considered to be refractory to endocardial catheter ablation because it originates from the epicardial region. A 45-year-old woman had incessant ventricular tachycardia with a delta wave-like beginning of the QRS complex which was resistant to several antiarrhythmic drugs. The origin of the arrhythmia was at the mitral annulus on the antero-lateral left ventricular wall. The earliest endocardial activation preceded the QRS complex by 18 msec. After 7 sec of endocardial radiofrequency application ventricular tachycardia was terminated. During a 2 year follow-up ventricular tachycardia did not recur and only small numbers of premature ventricular contractions (< 100/day) were noted. VT with delta wave-like QRS morphology which originates from the basal region of the ventricle may be treated successfully with radiofrequency catheter ablation using an endocardial approach.

Radiofrequency catheter ablation of left ventricular outflow tract tachycardia from the coronary cusp: a new approach to the tachycardia focus

INTRODUCTION

Idiopathic ventricular tachycardia (VT) originating from the left ventricular outflow tract (LVOT) is rare. Previously reported were two cases of LVOT tachycardia which were treated with radiofrequency (RF) catheter ablation through endocardial aortomitral continuity. We report here a case of a repetitive LVOT tachycardia in which the QRS morphology during VT exhibited an atypical left bundle branch block and inferior axis. Pace mapping revealed that the origin of this VT was very close to the left sinus of Valsalva. Transcoronary cusp RF catheter ablation abolished the VT in this patient and is a new approach for the treatment of this kind of VT. The application of this approach to the other types of VT has yet to be determined.

Feasibility and safety of two French electrode catheters in the performance of electrophysiological studies

The aim of this study was to analyze prospectively the feasibility and safety of using 2 Fr versus 6 Fr standard electrode catheters for diagnostic electrophysiological study.

METHODS

Two hundred and five consecutive patients were randomized to receive the 6 Fr approach (3 quadripolar, 6 Fr, electrode catheters inserted through the left or right femoral vein and placed in the high right atrium, right ventricular apex, and His bundle area) or the 2 Fr approach (3 quadripolar, 2 Fr, electrode catheters inserted through a single, 7 Fr, triple lumen, guiding catheter and positioned at the same sites as the 6 Fr approach).

RESULTS

Introduction time was shorter in the 2 Fr group (133.3 +/- 65 s, range 87-669 s) than in the 6 Fr group (242.8 +/- 91.8 s, range 168-1024 s, P < 0.001). The overall fluoroscopy time was longer in the 2 Fr group (141.2 +/- 40.1 s, range 78-312 s) than in the 6 Fr group (126.4 +/- 39.7 s, range 58-341 s, P = 0.009). However in the last 100 patients there was no more difference between the two groups (137.6 +/- 28.2 s vs 128.4 +/- 23.2 s, P = 0.07). There was no significant difference between 2 Fr and 6 Fr groups in the mean atrial (5.9 +/- 2.2 mV, range 2.2-11.3 mV, vs 6.1 +/- 2.3 mV, range 2.4-12.4 mV, P = 0.57) and ventricular (5.6 +/- 2.1 mV, range 1.9-9.7 mV, vs 5.7 +/- 2.2 mV, range 2.3-10.5 mV, P = 0.66) activation potential amplitudes recorded during sinus rhythm, or in the rate of stable His bundle potential recording (P = 0.3), and catheter dislodgment (P = 0.54). The overall number of complications was significantly higher in the 6 Fr group than in the 2 Fr group (29 vs 5, P = 0.001), as well as the number of entry site related complications (3 vs 12, P = 0.02) and catheter manipulation related complications (2 vs 17, P < 0.001).

CONCLUSIONS

The results of this study show that the use of 2 Fr electrode catheters reduces the rates of entry site and catheter manipulation related complications during EPS. Despite their small size, these catheters allow quick and precise positioning of the electrode.