Idiopathic ventricular arrhythmias originating from the papillary muscles in the left ventricle: prevalence, electrocardiographic and electrophysiological characteristics, and results of the radiofrequency catheter ablation.

INTRODUCTION: Idiopathic ventricular arrhythmias (VAs) can originate from the left ventricular (LV) papillary muscles (PAMs). This study investigated the prevalence, electrocardiographic and electrophysiological characteristics, and results of catheter ablation of these VAs, and compared them with other LV VAs. METHODS AND RESULTS: We studied 71 patients with VAs originating from the LV anterolateral and posteroseptal regions among 159 patients undergoing successful catheter ablation of idiopathic LV VAs. PAM VAs were uncommon, rare in a sustained form, and more common from the posterior papillary muscle (PPM) than anterior papillary muscle (APM). A younger age was a good predictor for differentiating left posterior fascicular VAs from PPM VAs. There were several electrocardiographic features that accurately differentiated PAM and LV fascicular VAs from mitral annular VAs. However, an R/S ratio < or =1 in lead V6 in the LV anterolateral region and a QRS duration >160 ms in the LV posteroseptal region were the only reliable predictors for differentiating PAM VAs from LV fascicular VAs. A sharp ventricular prepotential was recorded at the successful ablation site during 42% of the PAM VAs. Radiofrequency current with an irrigated or conventional 8-mm tip ablation catheter was required to achieve a lasting ablation of the PAM VA origins whereas that with a nonirrigated 4-mm tip ablation catheter produced excellent results in LV fascicular and mitral annular VAs. CONCLUSIONS: There are differences in the electrocardiographic and electrophysiological features among VAs originating from these regions that are helpful for their diagnosis and effective catheter ablation.

Catheter ablation of ventricular arrhythmias originating in the vicinity of the His bundle: significance of mapping the aortic sinus cusp.

BACKGROUND: There is a close anatomical relationship between the right coronary cusp (RCC) and noncoronary aortic cusp (NCC) and sites recording His bundle (HB) activation in the right ventricle (RV). OBJECTIVE: The purpose of this study was to examine the electrocardiographic and electrophysiological characteristics of ventricular arrhythmias (VAs) that originate near the HB and their potential as predictors of successful catheter ablation sites. METHODS: We studied 147 consecutive patients undergoing successful catheter ablation of idiopathic VAs originating from the ventricular outflow tract of either ventricle or the HB region. RESULTS: In 13 (9%) patients with an origin in the RCC (n = 5), NCC (n = 1), or RV HB region (n = 7), the local RV activation in the HB region preceded the QRS onset. In two VAs originating from the RCC or NCC, failed radiofrequency applications near the HB region in the RV delayed the near-field ventricular electrogram and separated the far-field electrograms before the QRS onset in the HB region. The QRS transition in the precordial leads did not discriminate between an RV origin near the HB and an NCC or RCC origin. A QS pattern in lead aVL might be helpful for predicting an RCC origin. CONCLUSIONS: VAs originating near the HB have similar electrocardiographic and electrophysiological characteristics, regardless of whether the ablation site is in the RV or aortic sinuses because of the close anatomical relationship of these structures and rapid transseptal conduction. When RV mapping reveals an earliest ventricular activation in the HB region during VAs, mapping in the RCC and NCC should be added to accurately identify the site of origin.

Electrocardiographic characteristics of ventricular arrhythmias originating from the junction of the left and right coronary sinuses of Valsalva in the aorta: the activation pattern as a rationale for the electrocardiographic characteristics.

BACKGROUND: Ventricular arrhythmias (VAs) may arise from the aortic sinuses and have electrocardiographic and electrophysiological characteristics that suggest a left (LCC) or right coronary cusp (RCC) origin. However, VAs that arise near the junction of those two cusps (L-RCC) may have unusual features. OBJECTIVES: The purpose of this study was to examine the electrocardiographic and electrophysiological characteristics of VAs arising from the L-RCC. METHODS: We studied 155 patients with idiopathic VAs with either left or right bundle branch block and an inferior QRS axis morphology and five control subjects undergoing a pacing study. RESULTS: For 146 of the 155 patients, the origin determined by the successful ablation site was at the L-RCC in five, LCC in 13, RCC in six, non-coronary cusp in two, right ventricular outflow tract in 108, left ventricular outflow tract in five, left ventricular epicardium in four, and pulmonary artery in three. A qrS pattern in leads V1-V3 was observed only in the VAs with an L-RCC origin. The propagation map revealed that the direction of the propagating wave front from the L-RCC origin produced a vector compatible with a q wave and that the anterior activation to the right ventricular outflow tract via the LCC or RCC formed the r wave. Pacing performed at multiple sites in the aortic root in the control subjects demonstrated that only pacing from the L-RCC could reproduce a qrS pattern in leads V1-V3. CONCLUSIONS: This study revealed that a qrS pattern in leads V1-V3 suggests a site of origin at the L-RCC.

Biventricular ICD implantation using the iliofemoral approach: providing CRT to patients with occluded superior venous access.

A 32-year-old woman with a history of nonischemic dilated cardiomyopathy, left bundle branch block, left ventricular ejection fraction of 0.15, and New York Heart Association Class III congestive heart failure, despite optimal medical treatment, was referred for cardiac resynchronization therapy with implantation of an implantable cardioverter defibrillator. The patient had prior chemotherapy for non-Hodgkin's lymphoma and was shown to have chronic total occlusion of the superior vena cava (SVC) by magnetic resonance imaging. Cardiac resynchronization was accomplished with an iliofemoral approach without complications resulting in marked clinical improvement. We conclude that the iliofemoral approach allows transvenous implantation of cardiac resynchronization therapy in patients with superior vena cava occlusion.

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.

Electrophysiologic and electrocardiographic characteristics and radiofrequency catheter ablation of focal atrial tachycardia originating from the left atrial appendage.

BACKGROUND: The left atrial appendage (LAA) is one of the major sources of focal atrial tachycardias (ATs). OBJECTIVE: The purpose of this study was to investigate the detailed electrophysiologic characteristics and catheter ablation of focal ATs originating from the LAA. METHODS: The study population consisted of 47 consecutive patients with 50 focal ATs originating from the left atrium (LA): LAA in 13, left pulmonary veins (PVs) in 14, right PVs in 12, and mitral annulus in 11. Programmed electrical stimulation and pharmacologic testing were performed to examine the mechanism of LAA AT. Left atriography was performed prior to radiofrequency ablation to identify the focus in the LAA. RESULTS: The mechanism of LAA AT was automaticity in 11 and triggered activity in 2. The 13 LAA foci were located mainly at the LAA base: 11 on the medial side and 2 on the lateral side. Atrial activation sequences within the distal coronary sinus were helpful in differentiating these LAA foci. The criterion of a negative P wave in leads I and aVL indicating an LAA AT focus was associated with sensitivity of 92.3%, specificity 97.3%, positive predictive value 92.3%, and negative predictive value 97.3%. No complications occurred in any of the 13 patients. All 13 patients were free of atrial arrhythmias without any antiarrhythmic drugs during follow-up of 8 +/- 3 years. CONCLUSION: LAA ATs have typical electrophysiologic and electrocardiographic characteristics that are helpful in guiding radiofrequency catheter ablation.

Left ventricular lead implantation in an unusual anatomy of the proximal coronary sinus.

A 62-year-old man with Class III heart failure and left bundle branch block underwent cardiac resynchronization therapy. Because prior implantation attempts from the left side were unsuccessful, the right side approach was attempted. However, it was still impossible to advance the pre-shaped sheaths into the distal coronary sinus (CS) because the CS was abnormal with a posterior vertical take off followed by a sharp sigmoid curve before the AV groove. Ultimately, a straight sheath was adjusted to fit the sigmoid curve with the guidance of an electrophysiologic catheter and a left ventricular lead was then passed into the anterolateral vein.

Efficacy of electroanatomic mapping in the catheter ablation of premature ventricular contractions originating from the right ventricular outflow tract.

BACKGROUND: Mapping of premature ventricular contractions (PVCs) originating from the right ventricular outflow tract (RVOT) sometimes is not easy because of an unstable incidence and multiple foci of the PVCs. The aim of this study was to evaluate the effectiveness of electroanatomic mapping in catheter ablation of those PVCs. METHODS AND RESULTS: One hundred patients with 134 RVOT origin PVCs were randomly allotted to undergo either conventional (group I; 50 patients with 65 PVCs) or electroanatomic mapping (group II; 50 patients with 69 PVCs). In group II, electroanatomic mapping of the RVOT was performed using auto-freeze maps in patients with frequent PVCs, and pace mapping was performed marking the pacing sites on the remap which was made by extracting the anatomic frame out of the baseline map during sinus rhythm in patients with infrequent PVCs. Successful ablation was achieved in 44 (88%) group I patients and 48 (96%) group II patients (p = 0.14). The fluoroscopy and procedure times and those per PVC morphology were all significantly shorter in group II than group I overall (p < 0.0001 for all comparisons), and in each patient group with infrequent PVCs, frequent PVCs or unstable PVCs (p < 0.05-0.0001). The number of RF applications and that per PVC was significantly smaller in group II than group I (5.3 +/- 1.8 vs 6.2 +/- 2.4, and 4.4 +/- 1.2 vs 5.2 +/- 2.1; p < 0.05). CONCLUSIONS: The use of electroanatomic mapping may reduce the fluoroscopy and procedure times in the ablation of RVOT PVCs, but there is no evidence that it improves the overall efficacy of the procedure.

Totally Implantable IV Treprostinil Therapy in Pulmonary Hypertension Assessment of the Implantation Procedure.

BACKGROUND: Prostacyclins improve symptoms and survival in pulmonary arterial hypertension (PAH). In response to risks associated with external delivery systems, an implantable IV infusion system was developed. A multicenter, prospective, single-arm, clinical trial (DelIVery for PAH) was conducted to evaluate this system for treprostinil in PAH. This analysis describes the findings related to the implant procedure. METHODS: Patients (N = 64) with PAH (World Health Organization group 1) receiving stable IV treprostinil were enrolled. Patients were transitioned to a temporary peripheral IV infusion catheter prior to the procedure. System implantation was performed at 10 centers under general anesthesia or deep IV sedation by clinicians from various specialties. Central venous access was via the cephalic, subclavian, jugular, or axillary vein. Using an introducer and fluoroscopic guidance, the distal tip of the infusion catheter was placed at the superior caval-atrial junction. The catheter was tunneled from the venous access site to an abdominal subcutaneous pocket, where the pump was placed. RESULTS: Of the 64 patients enrolled, four exited prior to implantation. All 60 implant procedures were successful. At baseline, all patients were receiving treprostinil via an external pump at a mean dose of 71.4 ± 27.8 ng/kg/min (range: 22-142 ng/kg/min). The implant averaged 102 ± 32 min (range: 47-184 min). Clinically significant implant procedure-related complications included one pneumothorax, two infections, and one episode of atrial fibrillation. There were three postimplantation catheter dislocations in two patients. Common implant-related events that were not complications included implant site pain (83%) and bruising (17%). CONCLUSIONS: The procedure for inserting a fully implantable system for treprostinil was successfully performed, with few complications. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01321073; URL: www.clinicaltrials.gov.

Pre-Clinical Investigation of a Low-Intensity Collimated Ultrasound System for Pulmonary Vein Isolation in a Porcine Model.

OBJECTIVES: The purpose of this study was to assess the feasibility of pulmonary vein (PV) isolation using low-intensity collimated ultrasound. BACKGROUND: Contemporary approaches to PV isolation are limited by the technical complexity of mapping and ablation. We describe a novel approach to left atrial anatomic rendering and PV isolation that aims to overcome some of these limitations by using low-intensity collimated ultrasound (LICU) system, which allows for near real-time geometry creation and automated ablation in a porcine model. METHODS: Twenty swine were anesthetized, and the LICU ablation catheter was placed in the left atrium via percutaneous transseptal access. Ultrasound M-mode-based anatomies of the inferior PVs were successfully created, and ablation was performed under automatic robotic control along a user-defined lesion path. One animal was excluded because of device failure. RESULTS: All target PVs in the 19 remaining animals were isolated acutely, requiring a mean of 1.6 applications. Ten animals were sacrificed acutely, and the remaining 9 survived for 35 ± 11 days. Of these 9, 1 animal was excluded from analysis because the index lasso position could not be reliably recreated. PVs in 5 of 8 animals remained isolated at sacrifice. Of the 77 total histological sections, 62 lesions (80.5%) were noted to be transmural. Lesions were homogeneous and characterized by coagulative necrosis and fibrous tissue. The mean myocardial thickness was 2.66 ± 1.80 mm, and the mean lesion depth was 4.28 ± 1.97 mm. No extra cardiac or collateral lesions were noted. CONCLUSIONS: This study demonstrates the safety and efficacy of a novel noncontact ultrasound mapping and ablation system to produce continuous transmural lesions that can isolate PVs in a porcine model.

Usefulness of three posterior chest leads for the detection of posterior wall acute myocardial infarction.

A significant proportion of patients with myocardial infarction are missed upon initial presentation to the emergency department. The 12-lead electrocardiogram (ECG) has a low sensitivity for the detection of acute myocardial infarction, especially if the culprit lesion is in the left circumflex artery (LCA). This study was designed to evaluate the benefit of adding 3 posterior chest leads on top of the 12-lead ECG to detect ischemia resulting from LC disease, using a model of temporary balloon occlusion to produce ischemia. We studied 53 consecutive patients who underwent clinically indicated coronary interventions. At the time of coronary angiography, the balloon was inflated to produce complete occlusion of the proximal LCA. We recorded and analyzed the changes noted on the 15-lead ECG, which included 3 posterior leads in addition to the standard 12 leads. In response to acute occlusion of the LCA, the posterior chest leads showed more ST elevation than the other leads, and more patients had ST elevation in the posterior leads than in any other lead. The 15-lead ECG was able to detect>or=0.5 mm (74% vs 38%, p<0.0001) and >or=1 mm (62% vs 34%, p<0.0001) ST elevation in any 2 contiguous leads more frequently than the 12-lead ECG. In conclusion, the 15-lead ECG identified more patients with posterior myocardial wall ischemia because of temporary balloon occlusion of the LC than the 12-lead ECG. This information may enhance the detection of posterior MI in the emergency department and potentially facilitate early institution of reperfusion therapy.

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.

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.

Efficacy of pulmonary vein isolation in paroxysmal atrial fibrillation patients with a Brugada electrocardiogram.

BACKGROUND: Medical therapy of atrial fibrillation (AF) can be challenging in patients with Brugada electrocardiograms (ECGs). The purpose of this study was to investigate the efficacy of pulmonary vein (PV) isolation (PVI) in AF patients with Brugada ECGs. METHODS AND RESULTS: PVI was performed in 6 consecutive patients exhibiting Brugada ECGs (type I in 1, type II in 4, and type III in 1) at baseline. In all patients exhibiting type II or III Brugada ECGs but 1, the administration of sodium-channel blockers converted those ECG patterns to a type I. Five of 6 (83%) patients were free of symptomatic AF without any antiarrhythmic drugs after the first procedure. In the 1 remaining patient with AF recurrence and newly developed atrial tachycardia (AT), the residual conduction gaps of the 3 previously isolated PVs and a focal AT originating from the mitral isthmus were eliminated in the 2nd session. Finally, during the follow-up period (11+/-6 months) after the last procedure, all patients were free of any symptomatic atrial arrhythmias without any antiarrhythmic drugs. No other complications occurred. CONCLUSIONS: Because of the concerns of proarrhythmias with antiarrhythmic drugs, PVI may be an effective strategy for highly symptomatic patients with AF who have a Brugada ECG pattern.

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.

A wide QRS complex tachycardia with different initiation patterns: what is the mechanism?

A 47-year-old man with palpitations underwent electrophysiologic testing (EPS). Burst atrial pacing while infusing isoproterenol induced non-reproducible wide QRS tachycardias with an unusual pattern of an H-A-V activation with the same tachycardia cycle length and two different initiation patterns. The tachycardia had the earliest atrial activation at the His bundle region. No dual atrioventricular (AV) nodal physiology was demonstrated by programmed atrial stimulation. Though a definite diagnosis of AV nodal reentrant tachycardia was not obtained, slow pathway ablation was performed in order to avoid inadvertent AV block as a complication. Thereafter, no tachycardias were induced by repeat burst atrial pacing.

Atrial tachycardia with slow pathway conduction mimicking typical atrioventricular nodal reentrant tachycardia.

A 68-year-old woman with palpitations underwent electrophysiologic testing. During burst atrial pacing the PR interval exceeded the RR interval and induced a supraventricular tachycardia consistent with a typical AV nodal reentrant tachycardia (AVNRT). Radiofrequency ablation of the slow pathway during the tachycardia immediately produced 2 : 1 AV conduction. After slow AV nodal pathway ablation an atrial tachycardia (AT) remained inducible with the earliest atrial activation around the HB region. Radiofrequency ablation at the site of earliest atrial activation interrupted the AT without AV block. AT originating from the HB region with slow pathway conduction may mimic typical AVNRT.