Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Special Considerations for Ablation in Pediatric Patients

Key Points Children have the same variety of arrhythmia mechanisms as adults, but with a different distribution and often in different clinical settings. Despite physical similarities of older children to adults, children are not just little adults when it comes to the choice to proceed with and techniques for performing ablation; however, virtually all the techniques used in adults, including epicardial approaches, can be performed in…

Atrial Transseptal Catheterization

Key Points A detailed understanding of the anatomy of the atrial septum and its relationship with critical structures such as the aortic root and the posterior atrial wall is crucial to safely perform transseptal catheterization. A biplane fluoroscopy-guided technique using conventional fluoroscopic landmarks guided by diagnostic catheters in standard positions (e.g., coronary sinus, His bundle, noncoronary sinus of Valsalva) is the historical standard for atrial transseptal…

Complications Associated With Radiofrequency Catheter Ablation of Arrhythmias

Key Points Complications can occur in any aspect of catheter ablation procedures. Common and specific risks and complications of catheter ablation procedures are well established. New risks and complications associated with catheter ablation of new target cardiac tachyarrhythmias such as atrial fibrillation and epicardial ventricular tachycardias are still being recognized. Extracardiac complications can also occur as collateral damage during or after catheter ablation of atrial fibrillation…

Ablation of Ventricular Tachycardia With Percutaneous Hemodynamic Support

Key Points Hemodynamic instability precludes detailed activation and entrainment mapping in a significant percentage of patients presenting for scar-related ventricular tachycardia (Sc-VT) ablation. As a result, ablation of Sc-VT is often limited to substrate mapping and ablation performed in sinus rhythm. Substrate-based ablation is thought to be less effective in certain patient populations, such as those with nonischemic cardiomyopathy—because of the paucity of targets (late potentials,…

Ablation of Genetically Triggered Ventricular Tachycardia/Fibrillation—Focusing on Brugada Syndrome

Key Points The right ventricular outflow tract (RVOT) epicardium is the culprit arrhythmogenic substrate site of Brugada syndrome (BrS). Abnormal fractionated electrograms and double potential electrograms are localized only in the anterior aspect of the RVOT epicardium. Epicardial and interstitial fibrosis often coexists with abnormal electrograms. Radiofrequency ablation by targeting the substrate areas that are defined after ajmaline/procainamide results in normalization of the Brugada electrocardiogram pattern…

Ablation of Ventricular Tachycardia With Congenital Heart Disease

Key Points Tachycardia Mechanism Ventricular tachycardia based upon morphologic/anatomic variants of the congenital heart defect or ventricular incisions and patches/scar tissue Best example tetralogy of Fallot: right ventricular macroreentrant tachycardia through anatomically defined isthmuses, often involving the right ventricular outflow tract Mapping Substrate mapping combined with activation mapping and pace mapping to localize right ventricular anatomic isthmuses Proof of electrophysiologic findings by concealed entrainment and stimulus-to-QRS-delay…

Epicardial Approach to Catheter Ablation of Ventricular Tachycardia

Key Points Percutaneous access to the pericardial space has improved our ability to characterize and modify arrhythmogenic epicardial scar substrates. Knowledge of pericardial anatomy and relevant surrounding structures is important for reducing and recognizing complications. Although implementation of epicardial mapping and ablation is variable, substrates with a high likelihood of epicardial scar and prior failed endocardial ablation are most likely to derive benefit from this adjunctive…

Substrate-Based Ablation for Ventricular Tachycardia

Key Points Mapping Arrhythmogenic substrate in ventricular tachycardia (VT) in the setting of structural heart disease is usually living but diseased myocardium within scar, which promotes reentry. This substrate can usually be identified and effectively targeted with ablation in sinus rhythm. Relevant substrate features are consistent with abnormal conduction and include (1) low-amplitude, high-frequency, bipolar signals, including late potentials in sinus rhythm or local abnormal ventricular…

Ablation of Unstable Ventricular Tachycardia and Ventricular Fibrillation

Key Points Substrate mapping is performed to delineate the scarred myocardium in unstable ventricular tachycardia (VT). For ventricular fibrillation (VF), mapping is performed to identify the focal origin of triggers. Targets for substrate ablation include VT exit sites identified by pace mapping, sites identified by brief resetting and entrainment mapping, late and fractionated potentials, sites with local abnormal ventricular activity, and channels between dense (“electrically unexcitable”)…

Ablation of Ventricular Tachycardia Associated With Nonischemic Cardiomyopathy

Key Points Mapping Entrainment mapping focusing on sites with concealed entrainment, pace mapping, electrogram-mapping focusing on sites with fractionated electrograms and isolated potentials Ablation Targets Myocardial fibers within scar tissue Special Equipment Preprocedural magnetic resonance imaging to assess for presence and location of scar tissue Intracardiac echocardiography to assess for intracardiac structures like papillary muscles, location of scar or aneurysms Sources of Difficulty Intramural and epicardial…

Ablation of Ventricular Tachycardia in Coronary Artery Disease

Key Points Mechanism The mechanism of postinfarction monomorphic ventricular tachycardia (VT) is generally reentrant myocardial excitation through surviving myocyte bundles within the infarct scar. Diagnosis and Mapping The diagnosis is made by excluding supraventricular and preexcited causes of broad complex tachycardia. Activation, entrainment, and substrate mapping techniques may all required to localize critical VT circuit components. Ablation Targets The basic critical target for ablation of postinfarct…

Ablation of Idiopathic Left and Right Ventricular and Fascicular Tachycardias

Key Points The mechanism of idiopathic mitral and tricuspid annular ventricular tachycardias (VTs) is nonreentry (triggered activity or automaticity). Mitral annular VT has a right bundle branch block (RBBB) pattern and monophasic R or Rs in leads V 2 to V 6 . Catheter ablation of mitral annular VT is highly successful. Tricuspid annular VT exhibits a left bundle branch block pattern, R (r) in lead…

Ablation of Ventricular Outflow Tract Tachycardias

Key Points Ventricular outflow tract tachycardias include the right or left ventricular (LV) outflow tracts, aortic cusps, pulmonary artery, and the corresponding epicardium (LV summit region). The mechanism underlying outflow tract arrhythmias is usually triggered activity, and the site of origin is focal. Activation mapping during arrhythmia is optimal to identify the site of earliest activation as the target for ablation. Mapping of outflow tract tachycardias…

Special Problems in Ablation of Accessory Pathways

Key Points The approach to the difficult accessory pathway ablation is, first, to exclude cognitive ablation failure by confirming the tachycardia diagnosis and reevaluating the electrograms. Second, use a systematic approach to identify contributing technical factors, such as pathway-related factors (including location and atypical configuration) and associated cardiac structural abnormalities. Finally, devise an appropriate strategy. This may include optimizing pathway localization, adjusting the ablation approach to…

Ablation of Atriofascicular Accessory Pathways and Variants

Key Points Atriofascicular accessory pathways are decrementally conducting accessory pathways that are most commonly located along the right free wall, connecting the atrium to the right bundle branch. They participate in antidromic tachycardia with a left bundle branch block morphology, antegrade conduction over the accessory pathway, and retrograde conduction over the atrioventricular node or another accessory pathway. The most effective method for ablating the atriofascicular pathway…

Catheter Ablation of Superoparaseptal (Anteroseptal) and Midseptal Accessory Pathways

Key Points Diagnosis of superoparaseptal ( anteroseptal ) and midseptal accessory pathways (APs) is made on the basis of an electrocardiographic pattern (if overt preexcitation is present) and evidence of midseptal/anteroseptal AP insertions during intracardiac mapping studies. Orthodromic supraventricular tachycardia using a midseptal AP must be differentiated from atrioventricular (AV) nodal reentry, and septal or parahissian atrial tachycardias. Mapping of superoparaseptal APs is used to locate…

Ablation of Posteroseptal Accessory Pathways

Key Points Posteroseptal accessory pathways (APs) are not true septal pathways but are located in the complex inferior pyramidal space involving the right atrium, right ventricle, left ventricle, left atrium, and coronary sinus and its branches. Mapping often needs to be performed in multiple regions including the septal tricuspid annulus, septal mitral annulus, proximal coronary sinus, and normal and abnormal branches of the coronary sinus including…

Ablation of Free Wall Accessory Pathways

Key Points The atrioventricular (AV) annulus is mapped for atrial or ventricular accessory pathway (AP) insertion sites or the AP itself. Ablation targets include the earliest site of atrial or ventricular activation by the AP, sites of AP potentials, and sites of electrogram polarity reversal (left free wall APs). Special equipment includes preformed sheaths (especially for the transseptal approach), multielectrode halo mapping catheters, and steerable sheaths…

Atrioventricular Junction Ablation for Heart-Rate Control of Atrial Fibrillation

Key Points Mapping uses a combined anatomy- and electrogram-guided approach. The right-sided approach target is just proximal to or below the His bundle electrode position on the fluoroscopic view, or at the proximal His location. The left-sided approach target is just below the aortic valve at the septal site where a His potential can be recorded. If the His potential is not recorded at the upper…

Ablation of Atrioventricular Junctional Tachycardias: Atrioventricular Nodal Reentry, Variants, and Focal Junctional Tachycardia

Key Points Mechanism of atrioventricular nodal reentrant tachycardia (AVNRT) is reentry involving fast and slow atrioventricular (AV) nodal pathways. The typical slow–fast form of AVNRT is diagnosed by the presence of a long atrium–His bundle (AH) interval (>180 ms) during tachycardia, with the earliest retrograde atrial activation localized at the level of the superior part of the triangle of Koch, just behind the tendon of Todaro…