Performing transcatheter left atrial appendage closure: Techniques and challengesThe left atrial appendage (LAA) has been demonstrated to be the major source of thromboemboli in patients with atrial fibrillation.1 The rationale of LAA closure is based on eliminating LAA continuity with the left atrium (LA), thereby reducing stroke risk. Indeed, left atrial appendage occlusion (LAAO) procedures play an important role in anticoagulation-intolerant patients who are at risk for atrial fibrillation–related stroke. Based on the PROTECT AF (Watchman Left Atrial Appendage System for Embolic PROTECTion in Patients With Atrial Fibrillation)2 and PREVAIL (Prospective Randomized Evaluation of the WATCHMAN LAA Closure Device in Patients With Atrial Fibrillation [AF] Versus Long Term Warfarin Therapy)3 studies, the Food and Drug Administration (FDA) approved use of the Watchman (Boston Scientific, Marlborough, MA) device in 2015, with an updated generation of device subsequently ratified in 2020 following the PINNACLE-FLX (Protection Against Embolism for Nonvalvular AF Patients: Investigational Device Evaluation of the Watchman FLX LAA Closure Technology) study.
How to perform an epicardial ventricular tachycardia ablation: A contemporary and practical approachCatheter ablation is increasingly used for the treatment of cardiac arrhythmias. In the 1990s, in order to treat ventricular arrhythmias resulting from chagasic cardiomyopathy, Sosa et al1 developed a technique to enter the pericardium percutaneously in the absence of a pericardial effusion. Since then, “dry” epicardial access has become a regular part of complex catheter ablation. In this review, we concentrate on the technical aspects of performing epicardial ablation for ventricular tachycardia (VT), including the management of potential complications.
How to perform ethanol ablation of the vein of Marshall for treatment of atrial fibrillationThe arrhythmogenicity of the vein of Marshall (VoM) in atrial fibrillation (AF) has been known for more than 20 years.1 A recent randomized trial showed a reduced odds ratio (0.63; 95% confidence interval 0.41–0.97; P = .04) for the primary outcome of AF or atrial tachycardia (AT) recurrence in patients with persistent AF by adding VoM ethanol infusion (VoM-Et) to the standard ablation approach.2 The VoM is involved in 30% of ATs after AF ablation, and VoM ablation significantly improves the freedom from recurrent arrhythmia.
Left atrial appendage occlusion using intracardiac echocardiographyLeft atrial appendage (LAA) closure (LAAC) has emerged as an alternative prevention strategy for patients with nonvalvular atrial fibrillation and contraindications to long-term anticoagulation.1 In randomized trials studying the Watchman device (Boston Scientific, St. Paul, MN), implantation was performed under transesophageal echocardiography (TEE) guidance.1 The use of TEE often mandates the presence of general anesthesia and an additional cardiologist or anesthesiologist to perform TEE. This uses greater health care resources and adds additional complexity to the procedure.
How to use intracardiac echocardiography to guide catheter ablation of outflow tract ventricular arrhythmiasThe anatomy of the ventricular outflow tracts and semilunar valves as it pertains to catheter ablation of outflow tract ventricular arrhythmias (OTVAs) has been described.1 Assessment of semilunar valve and regional anatomy by fluoroscopy and angiography has limitations. Coronary arteries may be subject to damage from catheter ablation near the semilunar valves due to their proximity to sites of origin of OTVAs. Detailed intracardiac echocardiographic (ICE) views of the semilunar valves may be useful to understand the anatomy, catheter location, and coronary artery proximity and variations.
When bigger is better: Novel use of a 27 F leadless pacemaker delivery sheath for femoral lead extractionsAs the implantation rate of cardiac implantable electronic devices has continued to increase, lead extractions for clinical indications such as infection, lead failure, and lead recall have also increased.1 A femoral approach to transvenous lead extractions is needed when removing previously cut and abandoned leads, leads that disrupt during a superior extraction attempt and in some cases involving central venous obstruction.2
A beginner's guide to permanent left bundle branch pacingStudies have demonstrated the feasibility and clinical benefits of permanent His-bundle pacing (HBP).1 However, concerns regarding higher pacing thresholds, lower R-wave amplitudes, and the potential to develop distal conduction block have limited the clinical application of HBP in certain subgroups.1,2
Mitral isthmus ablation: A hierarchical approach guided by electroanatomic correlationMitral isthmus ablation is an established technique used to treat perimitral atrial flutter. The classic approach involves creating an ablation line connecting the left inferior pulmonary vein (LIPV) to the lateral mitral annulus.1 Its feasibility was first prospectively studied by Jais et al,1 who reported a high rate of bidirectional block. However, subsequent studies by the same group, as well as others, have been less promising.2 This is important because failure to achieve bidirectional block with ablation has been shown to be proarrhythmic.
Retrograde venous ethanol ablation for ventricular tachycardiaRadiofrequency catheter ablation (RFCA) has been considered the first-line therapy for treatment of drug-refractory ventricular arrhythmias (VAs).1 The success of catheter ablation depends on our ability to reach the anatomic location of the ventricular tachycardia (VT) substrate. VTs arising from deep intramural regions2 or in close proximity to coronary vessels3 can have limited RFCA success. Transarterial coronary ethanol ablation has been used as an alternative treatment option and is reasonably successful in treating RFCA-refractory VTs.
Cosmetic aspects of device implantationThe cosmetic aspects of device implantation imply achieving an aesthetically pleasing surgical result. It involves concealing the cardiac implantable electronic device, avoiding unsightly scars, device bulges, and protrusion (Figure 1). Cosmetic device implantation is indicated for the extremely thin patient at risk of erosion and the young patient concerned with body image. These techniques are also important in the pediatric population, patients with burn injury, and patients after mastectomy.
How to perform left atrial appendage electrical isolation using radiofrequency ablationAlthough pulmonary vein (PV) isolation (PVI) has been considered an effective treatment for paroxysmal atrial fibrillation (AF), non-paroxysmal AF is a complex arrhythmia for which no ablation strategy has been demonstrated to be effective and widely accepted. As such, a success rate of ∼55% in these patients with AF (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial Part II [Star AF II trial]) is not acceptable in our opinion and efforts should be made to seek for alternative strategies.
Approach to permanent His bundle pacing in challenging implantsRight ventricular apical pacing has been the cornerstone of bradycardia pacing for decades. It is well established that right ventricular pacing leads to ventricular dyssynchrony, reduced left ventricular function, and heart failure.1,2 Since the initial description of permanent His bundle pacing (HBP) by Deshmukh et al in 2000,3 several investigators have demonstrated the clinical utility of HBP in patients with atrioventricular (AV) nodal block, infranodal AV block, and bundle branch block.4–7 Increasing interest in HBP has been hampered in part by challenges and limitations associated with a limited implantation tool set.
How to map and ablate parahisian ventricular arrhythmiasVentricular tachycardia (VT) and premature ventricular contractions (PVCs) originating in the vicinity of the His-bundle region represent 3%–9% of all idiopathic ventricular arrhythmias (VAs).1,2 In addition, patients with cardiomyopathies and scar-related VT may exhibit septal arrhythmogenic substrate involving the parahisian region.3 Catheter ablation of these arrhythmias poses particular challenges because of the risk of inadvertent atrioventricular (AV) block, and a systematic approach is important to improve outcomes and minimize complications.
Implantation of the subcutaneous implantable cardioverter–defibrillator with truncal plane blocksOperative anesthetic requirements and perioperative discomfort are barriers to wide adoption of the subcutaneous implantable cardioverter–defibrillator (SICD) system. The SICD implant procedure involves incision and dissection in the richly innervated midaxillary line of the chest wall for placement of the pulse generator and tunneling in subcutaneous tissue for implantation of the defibrillator lead.1 Intraoperative local anesthetic wound infiltration is routine and provides moderate analgesia, but the effects are short-lasting, and complete coverage of the affected areas is difficult.
Evaluation of shortness of breath after atrial fibrillation ablation—Is there a stiff left atrium?Ablation has emerged as the most effective therapy for atrial fibrillation (AF), with the primary goal to improve symptoms. However, there is a subset of patients who develop limiting symptoms after successful ablation despite reestablishment of sinus rhythm. There is now recognition of “stiff left atrial (LA) syndrome” related to adverse consequences of ablation itself on LA hemodynamics, as described by Gibson and others.1,2 Although relatively uncommon (1.4% incidence in the Gibson series), this syndrome is important to diagnose, as it can cause severe unexplained dyspnea.
Transcatheter/leadless pacingEntirely self-contained cardiac pacing systems for direct implantation within the heart via deflectable catheter are now available for use in humans. Worldwide, there have been more 7000 implants of the “transcatheter” or “leadless” pacemaker.∗ The concept of these pacing systems is far from new; Spickler et al.1 were able to achieve cardiac pacing in animals using a capsular nuclear-powered system in 1970. However, only recently has technology enabled sufficient miniaturization to make transcatheter pacing feasible.
When and how to target atrial fibrillation sources outside the pulmonary veins: A practical approachPulmonary vein (PV) isolation is an effective procedure in patients with paroxysmal atrial fibrillation (AF). For most patients with persistent AF and a subset of patients with paroxysmal AF, however, PV isolation may not be sufficient. Patients with the persistent form are more often beleaguered with comorbidities, which result in a greater degree of structural alterations that contribute to the maintenance of AF. In addition, the atrial activation rate during AF is higher (as evidenced by a shorter AF cycle length) in patients with persistent AF, consistent with a greater degree of electrical remodeling.
How to perform transconduit and transbaffle puncture in patients who have previously undergone the Fontan or Mustard operationThe incidence of arrhythmia is high in patients who have undergone a surgical procedure for complex congenital heart disease.1 Catheter ablation is a good therapeutic option to achieve a cure for tachyarrhythmia or a decrease in tachycardia burden. However, there are considerable limitations for a catheter approach to the heart in patients who have undergone a lateral tunnel or extracardiac conduit Fontan operation or an atrial switch operation (eg, Senning operation or Mustard operation).2 In these patients, a transconduit or transbaffle puncture is needed for electrophysiological procedures.
How to map and ablate papillary muscle ventricular arrhythmiasThe papillary muscles (PMs) are a source of ventricular arrhythmias (VAs) in both structurally normal and abnormal hearts. Presentation includes isolated premature ventricular contractions (PVCs), nonsustained ventricular tachycardia (VT), and sustained recurrent VT. In addition, PVCs arising from the PMs may play a role as triggers of ventricular fibrillation (VF).1,2 Because of their highly variable and complex anatomy and independent motion during the cardiac cycle, catheter ablation is challenging, with lower procedural success and higher recurrence rates compared with other locations.
Fluoroless catheter ablation of atrial fibrillationAlthough the concept of performing fluoroless catheter ablation of atrial fibrillation (AF) was introduced several years ago, it has yet to gain wide adoption.1,2 Despite its well-documented advantages, there are several impediments, including concern that a fluoroless approach will add time to the procedure and may require a second operator. However, perhaps the greatest obstacle is that many electrophysiologists are trained to rely on fluoroscopic imaging and are therefore reluctant to trust intracardiac echocardiography (ICE) as their primary visual modality for tracking catheter movement and manipulation.
Epicardial substrate ablation for Brugada syndromeBrugada syndrome (BrS), characterized by the presence of coved-type ST-segment elevation followed by T-wave inversion in the right precordial electrocardiogram (ECG) leads in patients who have no structural heart disease but have a high risk of sudden cardiac death from ventricular fibrillation (VF), has captivated arrhythmia scholars and electrophysiologists for more than 2 decades. As a result, major progresses have been made toward a better understanding of the syndrome with respect to its genetic basis, underlying pathophysiology, and risk stratification.
How to map and ablate left ventricular summit arrhythmiasCatheter ablation of idiopathic ventricular arrhythmias (VAs) is highly successful, with overall cure rates >90%, and is accepted as a first-line therapy by current guidelines.1 However, despite the advances in mapping and ablation techniques, there is a percentage of patients in whom successful ablation cannot be achieved because of anatomic limitations. In this regard, one of the most challenging clinical problems that electrophysiologists may face in the laboratory is the approach to VAs arising from the summit of the left ventricle (LV).
Novel approach to intraprocedural cardiac tamponade: Dual-site drainage with continuous suctionPericardial effusion and cardiac tamponade is an infrequent complication of invasive electrophysiologic procedures, with an estimated risk of 1%–3%.1–3 The most common procedures with increased risk for myocardial perforation are complex ablation during endocardial mapping and/or ablation, transseptal access, and lead placement for device therapy. Although early recognition with supportive management and immediate drainage with pericardiocentesis are necessary to prevent acute hemodynamic instability, the threshold for recommending surgical correction compared to conservative management is not well established.
How to perform permanent His bundle pacing in routine clinical practiceOver the years, various sites of ventricular pacing have been evaluated in clinical trials. Earlier trials established the detrimental effects of right ventricular (RV) apical pacing, including increased risk of atrial fibrillation, heart failure (HF), and mortality. Alternate RV pacing sites have yielded mixed results.1 Biventricular (BiV) pacing in advanced HF and electrical dyssynchrony reduced HF hospitalizations and mortality. Recently, 2 trials evaluated the clinical utility of BiV pacing in the setting of heart block and demonstrated equivocal results.
Enhanced cardiac device management utilizing the random EGM: A neglected feature of remote monitoringRemote monitoring (RM) of cardiac implantable devices is rapidly becoming the standard of care for implantable cardiac device follow-up.
Nodo- and fasciculoventricular pathways: Electrophysiological features and a proposed diagnostic algorithm for preexcitation variantsFasciculoventricular and nodoventricular pathways (FVP and NVP) are uncommon preexcitation variants that can be misleading during electrophysiology studies (EPSs), and differentiating them could be challenging.1–3 In this article, we describe 2 representative cases and then we present various electrophysiological features and phenomenon encountered in patients with these particular accessory pathways (APs).
Pulmonary vein signal interpretation during cryoballoon ablation for atrial fibrillationThe recognition that paroxysmal atrial fibrillation (AF) is predominantly triggered by ectopic beats arising from the vicinity of pulmonary veins (PVs) has spurred the establishment of percutaneous procedures specifically designed to electrically sequestrate the arrhythmogenic PV from the vulnerable left atrium (LA) substrate.1 Recently, the procedure has evolved with the development of purpose-built pulmonary vein isolation (PVI) tools, such as the cryoballoon catheter. This article discusses the anatomic and electrophysiologic bases for the interpretation of pulmonary vein potentials (PVPs) using a small-caliber circular mapping catheter (CMC) and provides an expanded discussion on the pacing maneuvers relevant to cryoballoon-based PVI procedures.
Prevention of phrenic nerve injury during interventional electrophysiologic procedures
The advent of innovative, potent ablative technologies and the adoption of endo–epicardial approaches to treat various arrhythmias have engendered a need for developing strategies to prevent collateral damage to critical structures such as the phrenic nerve (PN) and the esophagus during percutaneous electrophysiologic interventions. Here we detail phrenic nerve injury (PNI) prevention strategies during atrial fibrillation (AF), atrial tachycardia (AT), and ventricular tachycardia (VT) ablation. PNI is more common on the right side because of the anatomic course of the nerve and the greater preponderance of AF and AT ablations.
Safety and prevention of complications during percutaneous epicardial access for the ablation of cardiac arrhythmiasSince its introduction, percutaneous epicardial access is increasingly being performed to facilitate catheter ablation of ventricular tachycardias (VTs) with epicardial circuits, difficult cases of idiopathic VTs, focal atrial tachycardia, and accessory pathways that cannot be successfully targeted endocardially.1 A thorough understanding of the clinical anatomy and potential complications is vital in order to perform a safe procedure.2 In this article, we present the clinical anatomy related to epicardial access, the technique of performing a subxiphoid epicardial puncture, and various measures to prevent complications.
LAA ligation using the LARIAT suture delivery device: Tips and tricks for a successful procedureChronic oral anticoagulation (OAC) has traditionally been considered as the most effective prophylaxis against thromboembolic events in patients with atrial fibrillation (AF). However, as many as 20% of the patients with AF are not candidates for OAC.1,2 Reasons for ineligibility range from intracranial bleeding (the most serious complication) to increased propensity for mechanical injury (the least serious complication). The resumption of OAC in patients who have suffered a life-threatening complication due to OAC is associated with a much higher risk of such events in the future.
Safety and feasibility of transseptal puncture for atrial fibrillation ablation in patients with atrial septal defect closure devicesAF is often found in association with an ASD.1–4 There are an increasing number of patients undergoing transcatheter closure of an ASD who subsequently develop AF in clinical practice.2–4 Catheter ablation has emerged as an effective treatment strategy for drug-refractory symptomatic AF.5 While transseptal access to the left atrium (LA) is a prerequisite for AF ablation, it may prove difficult in the presence of an ASD closure device.6,7 Anticipating technical difficulties and potential complications may discourage operators from considering catheter ablation of AF in this particular patient population.
Two-incision technique for implantation of the subcutaneous implantable cardioverter-defibrillatorThree incisions in the chest are necessary for implantation of the entirely subcutaneous implantable cardioverter-defibrillator (S-ICD). The superior parasternal incision is a possible risk for infection and a potential source of discomfort. A less invasive alternative technique of implanting the S-ICD electrode—the two-incision technique—avoids the superior parasternal incision.
How to perform ventricular tachycardia ablation with a percutaneous left ventricular assist deviceA majority of patients with structural heart disease and scar-related ventricular tachycardia (VT) have fast, hemodynamically unstable VT.1 In fact, up to one-fifth of the patients have only unstable VT, which precludes detailed activation and entrainment mapping.2 In addition, even in those with well-tolerated VT, procedural success can be complicated by acute heart failure as a consequence of prolonged episodes of induced VT and intravascular volume expansion; and one consequence of this acute decompensated heart failure is a significant increase in the short-term morbidity and mortality of the procedure.
A straightforward, reliable technique for retaining vascular access during lead replacementDuring the removal or replacement of device leads, it is often desirable to retain vascular access, which removes any risk of complications from venous cannulation techniques. In this article, I describe a rapid, safe, and flexible technique for the replacement of a nonadherent device lead while preserving vascular access.
How to perform antral pulmonary venous isolation using the cryoballoonThis article describes our current practice, clinical outcomes, and future directions for the use of balloon cryoablation for the treatment of atrial fibrillation.
Management of hemopericardium related to percutaneous epicardial access, mapping, and ablationPercutaneous epicardial access (Figs. 1A and 1B) has gained wide acceptance as an interventional technique to access the pericardial space. Since its initial description1 in targeting epicardial circuits of ventricular tachycardia (VT) in patients with Chagasic cardiomyopathy, percutaneous epicardial access and ablation has come to play an important role in interventional electrophysiology. This technique has been recognized as a vital addition to catheter ablation of certain cardiac arrhythmias and for the delivery of newer investigational devices such as epicardial suture ligation of the left atrial appendage.
Recording and interpreting unipolar electrograms to guide catheter ablationElectrophysiology laboratories commonly use closely spaced bipolar recordings for mapping. However, unipolar recordings have some useful features that can provide additional complimentary information, provided the limitations of these recordings and the particular recording techniques are recognized.
Implantable cardioverter-defibrillators in congenital heart disease: 10 programming tipsAdvances in cardiac care of the young have given rise to a growing and aging population of patients with congenital heart disease. Despite remarkable improvements in overall survival, sudden cardiac death remains the most common cause of late mortality. As a result, implantable cardioverter-defibrillators (ICDs) are increasingly used in this heterogeneous patient population. Tetralogy of Fallot and transposition of the great arteries are the most prevalent subtypes of congenital heart disease in ICD recipients.
Left cardiac sympathetic denervation for the prevention of life-threatening arrhythmias: The surgical supraclavicular approach to cervicothoracic sympathectomyThe progressive understanding of the diseases associated with significant risk for sudden cardiac death has fostered the development of early diagnosis and risk stratification. Thus, instead of starting from either a sudden death victim or a survivor of a cardiac arrest, it has become relatively common for cardiologists to identify individuals at high risk for sudden death, often after an arrhythmic nonlethal cardiac event such as syncope. Besides ischemic heart disease, it has also been recognized that children and young adults can be affected by arrhythmogenic disorders of genetic origin with a high propensity for lethal arrhythmias.
How to troubleshoot the electroanatomic mapAn electroanatomical mapping system is a useful tool for complex arrhythmia ablation. The system reconstructs the precise 3-dimensional chamber of interest with electrical and anatomical information. There are several technical aspects that physicians should be aware of to maximize its efficacy. This review provides relevant information on troubleshooting of the mapping system.
How to perform and interpret rotational angiography in the electrophysiology laboratorySophisticated imaging methods have been growing in popularity since the introduction of curative ablation procedures for atrial fibrillation (AF). This trend is predicated on the need for a precise anatomic guidance within the complex left atrial (LA) anatomy and less reliance on electrocardiographic characteristics of the substrate. Traditional two-dimensional imaging methods such as fluoroscopy would not satisfy the needs of a complex catheter navigation inside three-dimensional (3D) anatomic structures that may not be confined to the radiographic cardiac silhouette (e.g., pulmonary veins [PVs]).
How to implant a defibrillation coil in the azygous veinImplantable cardioverter-defibrillator (ICD) defibrillation testing may reveal failure to achieve a satisfactory safety margin (conventionally, ≥10 J below the maximum energy of the generator) for defibrillation. Options for modification of the defibrillation threshold include repositioning of the ventricular lead, use (or removal) of a defibrillation coil in the superior vena cava (SVC), reversal of shock polarity, and modifying the shock waveform (not available in all devices). Additional defibrillator coils can be added to the subcutaneous space, the subclavian vein, or the coronary sinus.
How to diagnose and treat cardiac tamponade in the electrophysiology laboratoryAs certain as death and taxes occur, complications will occur when invasive procedures are performed. Pericardial effusion, with or without tamponade, is a well-documented complication even in the most experienced centers.1,2 As a result, electrophysiologists should know how to recognize and manage this complication over the course of their careers. In most situations, the outcome is excellent if the complication is recognized and managed expeditiously; however, delay in diagnosis and treatment can lead to catastrophic results.
CRT delivery systems based on guide support for LV lead placementDespite improvements in LV pacing leads, their placement continues to be limited by the coronary venous anatomy. Frequently, the angioplasty wire does not provide adequate support to advance the LV lead into the vein. However, a guiding catheter preshaped to fit into the ostium of the target can easily provide the required support.1,2 Many implanting physicians are reluctant to adopt preshaped guides for direct LV lead delivery because of lack of familiarity with the approach to open lumen catheter manipulation and contrast injection.
How to use balloons as anchors to facilitate cannulation of the coronary sinus left ventricular lead placement and to regain lost coronary sinus or target vein accessCoronary venous anatomy can make successful implantation of a cardiac resynchronization therapy device difficult or impossible. Venogram and coronary balloons can be used as anchors to facilitate initial coronary sinus (CS) cannulation and left ventricular lead placement and to recover lost CS and target vein access.
Catheter ablation in tetralogy of FallotTetralogy of Fallot is the most common form of cyanotic heart disease, accounting for approximately 10% of congenital heart defects. Corrective surgery involves atrial and/or ventricular incisions and patches that, when combined with altered hemodynamics, predispose to the late onset of arrhythmias.1,2 In a multicenter cohort followed up for 35 years after corrective surgery, sustained atrial and ventricular tachyarrhythmias occurred in 10% and 12% of patients, respectively.1 Macroreentrant right atrial tachycardia is the most common atrial arrhythmia.
Catheter ablation in transposition of the great arteries with Mustard or Senning bafflesComplete transposition of the great arteries (D-TGA) accounts for 5% to 7% of congenital heart defects. Although the arterial switch procedure has now replaced atrial redirection as the surgical procedure of choice, most adults today with D-TGA have had Mustard or Senning baffles. These surgeries involve extensive atrial reconstruction and predispose to sinus node dysfunction and atrial tachyarrhythmias.1,2 By 20 years after surgery, the prevalence of atrial tachyarrhythmias is approximately 25%, continues to increase with time, and is similar among patients with Mustard or Senning baffles.
How to perform magnetic resonance imaging on patients with implantable cardiac arrhythmia devicesMagnetic resonance imaging (MRI) offers unrivaled soft tissue resolution and multiplanar imaging capabilities. Cardiac MRI is capable of accurate characterization of cardiac function and is uniquely capable of identifying scar fibrosis and fat deposition, thus making it an ideal imaging modality for the evaluation of patients presenting with arrhythmia. In addition, the absence of x-ray radiation makes MRI suitable for follow-up of chronic disease and for imaging in young patients and women of childbearing age.
How to identify the location of an accessory pathway by the 12-lead ECGRadiofrequency catheter ablation has become the treatment of choice for patients with symptomatic Wolff-Parkinson-White syndrome (WPW). The QRS complex morphology present on the 12-lead electrocardiogram (ECG) in WPW patients depends on the location of the accessory pathway(s) (AP) and the degree of fusion over the normal atrioventricular (AV) conduction. Accordingly, it is determined by the site of ventricular insertion of the accessory pathway, AV node conduction time, and atrial conduction.
Ablation above the semilunar valves: When, why, and how? Part IIn this two-part series, we discuss the anatomical basis for arrhythmias arising above the semilunar valves. In this part (part I), we describe the relevant anatomy and technique for mapping and ablation of ventricular arrhythmias arising above either the pulmonic or the aortic valve. After an initial discussion of the underlying anatomy and characteristics of the substrate targeted for ablation above the semilunar valve, an approach for safe and effective ablation of supravalvar ventricular arrhythmias is presented.
Ablation above the semilunar valves: When, why, and how? Part IIIn this two-part series on arrhythmias occurring above the semilunar valve, we discuss the relevant underlying anatomy and the technique for mapping and ablation above the aortic and pulmonic valve. In part I, we focused on ventricular arrhythmias, and in this paper (part II), we discuss the anatomy and present knowledge of the substrate mapped and ablated above the aortic valve for atrial tachycardia in certain unusual accessory pathways. The background anatomy of the aortic valve has been discussed in part I of this series, to which the reader is referred.
How to prevent, recognize, and manage complications of lead extraction. Part III: Procedural factorsThe major risks of percutaneous lead extraction include cardiac perforation (1%–4%), emergency cardiac surgery (1%–2%), and death (0.4%–0.8%). However, risk to an individual varies in accordance with a number of factors (Table 1), and informed consent must be tailored to the specific patient. Indicators of very high risk (Table 2) define relative contraindications to the procedure; patients without other options should be referred to experienced centers capable of managing these special cases. Surgical backup should be secured prior to every extraction.
How to avoid inappropriate shocksImplantable cardioverter-defibrillator (ICD) usage has increased dramatically over the past decade. In part this is due to improved patient survival after myocardial infarction, but principally this is due to the increased number of implants for primary prevention. While the salutary effects of ICD therapy in this population of patients are generally accepted, complications from ICD implantation have become a common and pressing issue. First among these complications, both in terms of frequency and impact on quality of life, is inappropriate ICD therapy.
Ablation using irrigated radiofrequency: A hands-on guideThe advent of irrigated radiofrequency (RF) catheters has led to the common misconception that irrigation somehow makes ablation both safer and more effective. In fact, this is not true. Irrigation (or any other means of cooling the catheter tip) results in the ability to deliver greater energy and as such can lead to steam pops, collateral damage, and thrombus formation. It is important to recognize that irrigation allows greater energy delivery; it does not mandate it. The operator must determine the appropriate power settings, irrigant flow rates, and lesion duration for each ablation site.
Novel ablative approach for atrial fibrillation to decrease risk of esophageal injuryPercutaneous atrial fibrillation (AF) ablation using catheter-delivered radiofrequency energy continues to improve in safety and effectiveness. Nonetheless, the potential risk of esophageal injury often limits the ability to fully ablate the posterior portion of the left atrium to achieve optimal procedural success without complications. We present a comprehensive approach that addresses this challenge. Our ablative strategies include (1) identifying the esophagus to minimize ablative energy, when possible, in the proximity of the esophagus, (2) maximize the ability of the esophagus to remove heat and to heal from potential thermal injury, and (3) optimizing energy delivery to avoid deep tissue injury while maintaining procedural efficacy.
How to prevent, recognize, and manage complications of lead extraction. Part II: Avoiding lead extraction—Noninfectious issuesThe first part of this review examined the infectious indications for lead extraction. This part discusses noninfectious indications for lead extraction and strategies for reducing the incidence of such indications.
How to prevent, recognize, and manage complications of lead extraction. Part I: Avoiding lead extraction—Infectious issuesAs the number of implanted devices continues to grow, so does the need for extraction of chronic endocardial leads. Extraction carries with it considerable risk of morbidity and mortality (both intraprocedure and postprocedure), even in experienced hands. Although the evolution of technology directed at this approach has facilitated the successful removal of leads, no evidence indicates that this technology has lessened the incidence or nature of adverse events. Risks associated with lead extraction include vascular and cardiac perforation, tricuspid valve injury, various arrhythmias, sepsis, pulmonary embolism, bleeding, stroke, and myocardial infarction.
Percutaneous extraction of coronary sinus vein and branch leadsExtraction of cardiac leads and electrodes will continue to be a statistical necessity as electrode implant numbers and durations increase. Improved implant success and expanded indications in heart failure patients for left ventricular (LV) pacing electrodes via the coronary sinus (CS) and its branches have resulted in unique interactions among the leads, venous system, and epicardial heart that are not typically seen with traditional endocardial right heart cardiac electrodes. LV lead placement, as well as the myocardium’s response to it, requires continual evaluation to better understand the limitations that may be encountered during extraction of LV leads, especially as the mean duration of implant reaches beyond 1 year.
European perspective on lead extraction: Part IIIf manual extraction is not successful, a locking stylet is used after the inner lumen is reamed using another stylet to remove debris. Use of a locking stylet with a very flexible tip is essential so that a tortuous lead can be negotiated. Equally important is locking the stylet as close as possible to the lead tip and not allowing the stylet to slip during the procedure. The risk of severing the sometimes fragile interpolar section of encapsulated bipolar leads is high if a positive lock close to the lead tip cannot be achieved.
A European perspective on lead extraction: Part IThe need for lead extraction has increased exponentially in the last decade due to greatly increased “total lead exposure time.” The increased total lead exposure time is the result of new indications for device treatment, device therapy involving more leads per patient, and longer average patient life. Improved general lead reliability noted over recent years may have decreased slightly the need for extraction; however, this effect is more than countered by recent advisories, recalls, and increased complication rates, probably related to many new centers offering device treatment.
How to treat and identify device infectionsThe incidence of device-related infections depends directly on the definition employed. The lack of precision is also compounded by the latency between the initiation and manifestation of the infection. It is not rare for there to be some erythema at the incision site during the first week of healing, and it is not clear that this represents infection. Less frequent, but still common, there can be a small, superficial stitch abscess, which will respond to local measures. When the diagnosis of device system infection is made, it should be made on the basis of pocket cellulitis, erosion, abscess, persistent bacteremia, or endocarditis with or without vegetation on the lead.
Lead extractionLead extraction has grown from a “niche” procedure practiced by a select few individuals to a fairly widely disseminated technique. With the apparent increase in device infections, occluded veins and the need for device “upgrades,” more physicians are attempting to extract chronically implanted pacing and implantable cardioverter-defibrillator (ICD) leads. Unfortunately, obtaining training for this procedure is difficult outside of a training program at a center with a physician experienced in lead extraction.
Lead extraction using the femoral veinLead extraction using the femoral vein is an alternate approach for lead removal. It has often been dubbed “the inferior approach.” This is because today it is often reserved for use only after a failed primary approach via the implant vein. In reality it is the most versatile approach for lead removal. Prior to the advent of powered sheaths, it was frequently used as a primary approach. It is also the only approach, and the procedure of choice, for removal of broken or cut leads with free ends.
How to select patients for lead extractionThe techniques and tools for percutaneous removal of transvenous leads have undergone substantial development over the past several decades. Although the use of locking stylets and powered sheaths to free leads from encapsulated scar tissue has improved the success rate, the procedure still carries a significant risk of morbidity and mortality even in the hands of experienced operators. The threshold for lead extraction continues to evolve. The initial use of the procedure was limited to patients with life-threatening infections because of limited tools, lower success rates and high complication rates.
How to perform linear lesionsAtrial fibrillation (AF) is a particularly complex arrhythmia because the mechanisms leading to fibrillation are not fully understood. Accordingly, ablation strategies have evolved largely on an empirical basis. The creation of linear lesions is a fundamental strategy that is indispensable to an electrophysiology laboratory performing ablation for treatment of this arrhythmia.
Pacing maneuvers for nonpulmonary vein sources: Part IISuperior vena caval (SVC) potentials are similar to pulmonary vein (PV) potentials. The concepts of multiple far-field electrograms and the use of perivenous pacing and specific site and simultaneous pacing described above are equally applicable to understanding the complex electrograms found within the SVC (Figure 1). Specific sites that require pacing to determine the components of a complex electrogram found in the SVC include the right atrium (RA), azygos vein, anomalous PVs draining into the SVC, and right upper PV; in some cases, an anomalous superior branch of the right inferior PV may be required.
Pulmonary vein–related maneuvers: Part IWith the rapid evolution of atrial fibrillation ablation procedures, electrophysiologists have necessarily strived for simple and anatomic-based approaches. In all except the most straightforward procedures, however, questions regarding the significance of various potentials recorded on mapping and ablation catheters arise.1,2 Other articles in this series have described in detail the various approaches to atrial fibrillation ablation. In this article, the anatomic and electrophysiologic bases for pacing maneuvers used with a variety of ablation approaches are reviewed.
How to determine and assess endpoints for left atrial ablationStudies have demonstrated that myocardium surrounding pulmonary vein (PV) ostia plays an important role in the initiation and perpetuation of atrial fibrillation (AF).1,2 This important finding has led to the development of segmental PV ostial isolation, circumferential ablation, and isolation around the PVs using circular linear lesions guided by three-dimensional (3D) electroanatomic mapping. Substrate modification using limited linear ablation also has been demonstrated to improve the clinical outcome after PV isolation in patients with AF inducibility.
How to recognize, manage, and prevent complications during atrial fibrillation ablationSeminal observations by Haissaguerre et al1 demonstrating initiation of atrial fibrillation (AF) by pulmonary vein (PV) depolarizations led to the development of percutaneous catheter-based endocardial AF ablation procedure. Since its original description, the AF ablation procedure has evolved considerably. Currently, the most accepted ablation strategy involves creating circumferential radiofrequency (RF) ablation lesions around PV ostia (either individually or encircling wide areas around the left-sided and right-sided veins) with or without additional atrial lesions.
How to use intracardiac echocardiography for atrial fibrillation ablation proceduresIntracardiac echocardiography (ICE) has been an important tool in the development of advanced catheter ablation procedures. ICE technology now allows complete echocardiographic interrogation of all four heart chambers from the right atrium. A list of the uses for ICE in ablation procedures is given in Table 1.
How and when to ablate the ligament of MarshallThe ligament of Marshall is an epicardial vestigial fold that marks the location of the embryologic left superior vena cava. It contains the nerve, vein (vein of Marshall), and muscle tracts.1,2 The proximal portions of the muscle tracts connect directly to the coronary sinus myocardial sleeves. The distal portions of the muscle tracts extend upward into the pulmonary vein region. Figure 1 shows a postmortem human heart with the ligament of Marshall located between the left atrial (LA) appendage and left pulmonary vein.
Catheter ablation of atrial fibrillation originating from extrapulmonary vein areas: Taipei approachThe pulmonary veins (PVs) are a dominant source of ectopic activity initiating atrial fibrillation (AF).1,2 We and others have demonstrated that extra-PV ectopic activity could initiate AF, and elimination of ectopic activity can cure this specific group of patients with AF.3-6 The Bordeaux group demonstrated that extensive ablation of extra-PV areas after isolation of all four PVs can convert chronic AF to focal or macroreentrant atrial tachycardias, and further elimination of these atrial tachycardias could maintain sinus rhythm in approximately 90% of patients with chronic AF.
How to perform ablation of the parasympathetic ganglia of the left atriumCatheter ablation of atrial fibrillation (AF) has generally consisted of eliminating pulmonary vein (PV) triggers initiating AF1 or modifying the adjacent atrial substrate to isolate the PVs.2 Mapping and ablation of complex fractionated atrial electrograms, thought to be responsible for maintaining AF, also have been reported.3 However, all of these strategies likely are associated with varying degrees of denervation, as suggested by experimental,4 clinical, and systematic analysis of the effects of modification of autonomic tone on the outcome of AF ablation.
How to do circular mapping catheter-guided pulmonary vein antrum isolation: The Cleveland Clinic approachAtrial fibrillation (AF) is one of the 20th-century epidemics. Over the past 2 decades, significant advances have been made in the treatment of AF, the last being percutaneous ablation. Haissaguerre et al1 showed that AF triggers often originate from the thoracic veins. The goal of present-day AF ablation is to electrically “disconnect” the pulmonary veins (PVs) from the rest of the left atrium (LA) by ablating around the origin of the veins.2 At present, at least two techniques are used for AF ablation.
How to perform electrogram-guided atrial fibrillation ablationOver the past decade, several mapping studies of human atrial fibrillation (AF) have made the following important observations: (1) Atrial electrograms during sustained atrial fibrillation have three distinct patterns: single potential, double potential, and complex fractionated potential(s) (CFAEs).1–3 (2) The distribution of these atrial electrograms during AF localizes to specific atrial sites, and these electrograms exhibit remarkable temporal and spatial stability.1,2 (3) The CFAE areas represent AF substrate sites and are important targets for AF ablation.
How to perform encircling ablation of the left atriumThe purpose of this article is to describe the technique and results of circumferential pulmonary vein ablation (CPVA) in patients with atrial fibrillation (AF) as currently performed in Milan.1–14 Since a significant learning curve still exists with the standard procedure, we have recently developed a new system, called remote magnetic navigation and ablation, which can be performed by less experienced operators while at the same time still reducing complications.13 The results of our standard technique with manually deflectable catheters are based on about 10,000 patients with paroxysmal, persistent, or permanent AF, many of whom have structural heart disease.
How to manage the patient with a high defibrillation thresholdDefibrillation threshold (DFT) testing is an integral part of implantable cardioverter-defibrillator (ICD) placement and follow-up. Unfortunately, the DFT can vary widely from day to day, influenced by many factors including electrolytes, sympathetic tone, antiarrhythmic drugs, and other medications. For this reason, a 10-J safety margin between the lowest successful defibrillation energy during testing and the maximal device output has been widely adapted as standard practice.1
How to select patients for atrial fibrillation ablationThe goals of therapy for atrial fibrillation (AF) are elimination of symptoms and improvement in quality of life; prevention of complications such as thromboembolic events and tachycardia-mediated cardiomyopathy; and, at least in theory, improvement in survival.
How to interpret and identify pulmonary vein recordings with the lasso catheterCurative catheter ablation of atrial fibrillation (AF) began with the recognition of ectopic impulses triggering AF, originating dominantly from the pulmonary veins (PV). Electrical isolation of the PV from the LA was proposed to eliminate these triggers from the PV and is now performed with the aid of a circumferential PV mapping (lasso) catheter. In addition to the initiating role of the PV, this structure is also critical as a substrate maintaining AF.1 The importance of PV isolation in AF ablative therapy therefore remains unchanged since the development of this technique whether it is for paroxysmal, persistent or permanent AF.
How to perform noncontact mappingThe anatomic and electrophysiologic complexity of arrhythmias subject to evaluation and catheter-based therapy has increased over the past several years. Use of advanced mapping systems, capable of three-dimensional rendering of cardiac chambers and superimposition of electrical information, are not designed to replace conventional mapping techniques but to be used as an adjunctive tool in the analysis and treatment of complex arrhythmias. EnSite 3000 (Endocardial Solutions, Minneapolis, MN) was the first component of the EnSite mapping system capable of advanced electroanatomic evaluation through novel catheter design and capabilities.
How to access the axillary veinThe axillary vein has become a desirable structure for venous access for implantation of defibrillator and pacemaker leads because the vein is large, easily accessed, and can accommodate multiple leads. Furthermore, axillary vein access is not associated with problems accompanying subclavian vein access, including pneumothorax and subclavian crush syndrome.1,2
How to interpret electroanatomic mapsElectroanatomic mapping refers to the acquisition and display of electrical information combined with spatial localization. Technologies presently available include both contact and noncontact electroanatomic mapping. This review focuses on the creation and proper interpretation of contact electroanatomic maps, which involves the sequential recording of unipolar or bipolar electrograms with a catheter in contact with the endocardium or epicardium and display of this information on a three-dimensional navigation system.
How to analyze T-wave alternansNoninvasive detection of patients prone to ventricular tachyarrhythmias and sudden cardiac death using measurements of ventricular repolarization derived from the 12-lead surface ECG has received enormous interest. Among the methods introduced for this purpose are assessment of QT dispersion, determination of QT dynamics assessed from long-term ECG recordings, and morphologic assessment of T-wave patterns. Analysis of microvolt T-wave alternans has emerged as the most promising. Considerable experimental evidence links microvolt T-wave alternans to the genesis of life-threatening ventricular tachyarrhythmias.
How to ablate left atrial flutterTypical atrial flutter ablation has become an increasingly common indication for catheter ablation, with success rates routinely exceeding 90% in most laboratories. In contrast, catheter ablation of left atrial flutter is technically challenging, and high success rates are uncommon.
How to manage patients with inappropriate sinus tachycardiaThe objective of this review is to provide an overview of current understanding of inappropriate sinus tachycardia, with a brief discussion on diagnosis, mechanisms, and therapy. I propose a broad and multidisciplinary management approach for the majority of patients with inappropriate sinus tachycardia.
How to ablate atrioventricular nodal reentry using cryoenergyMost electrophysiologists are well acquainted with the technique of radiofrequency (RF) ablation of AV nodal reentrant supraventricular tachycardia (AVNRT). This familiarity has, in turn, translated into a high degree of efficacy and safety with this method of ablation. On the other hand, catheter cryoablation is a relatively new approach for treating patients with AVNRT.1,2 Although the two ablation methods have certain similarities, understanding the unique features of cryoablation is important so that the method can be optimally used.
Locating focal atrial tachycardias from P-wave morphologyAtrial tachycardia (AT) foci tend to cluster at characteristic anatomic locations that can be gleaned from careful analysis of the P wave.
Atrial lead implantation in the Bachmann bundleThe search for alternative atrial pacing sites has been driven by the observation that atrial activation patterns can influence the incidence of atrial fibrillation (AF).1,2 One goal of atrial pacing is to prevent nonphysiologic delay between right and left atrial activation. Pacing from atrial sites that decrease dispersion of atrial refractoriness may decrease the incidence of AF.
Using the twelve-lead electrocardiogram to localize the site of origin of ventricular tachycardiaThe basis of this review is the underlying hypothesis that the QRS morphology on 12-lead ECG is, to a great extent, determined by the site from which a focal ventricular tachycardia (VT) arises or from which a reentrant circuit exits the central isthmus to activate the “normal” myocardium. The ability to localize or, at the very least, regionalize “the sites of origin” of VTs enables the electrophysiologist to concentrate mapping to a specific region. Several factors limit the ability of the QRS patterns to localize VT origin, including (1) presence and size of infarction, (2) degree of intramyocardial fibrosis, (3) shape of the heart (e.g., aneurysm) and its position within the chest cavity, (4) site and mechanism of VT within an infarct or scarred area, (5) influence of nonuniform anisotropy in affecting propagation from the site of the tachycardia, (6) effects of acute ischemia, antiarrhythmic drugs, or metabolic abnormalities on conduction, (7) integrity of the His-Purkinje system, (8) presence of increased myocardial mass, and (9) presence of structural abnormalities unrelated to tachycardia origin or mechanisms.
Para-Hisian pacing: Useful clinical technique to differentiate retrograde conduction between accessory atrioventricular pathways and atrioventricular nodal pathwaysPara-Hisian pacing is a useful tool to differentiate between retrograde conduction over an accessory pathway and retrograde conduction over the fast or slow atrioventricular (AV) nodal pathways.1–3 Para-Hisian pacing uses right ventricular (RV) pacing close to the His bundle or proximal right bundle branch (RBB). As the position of the ventricular pacing catheter changes subtly during respiration (or by changing pacing output), the pacing stimulus changes capture among (1) basal anteroseptal RV plus His bundle or proximal RBB (His bundle-RBB capture); (2) capture of basal anteroseptal RV alone; and (3) His bundle-RBB capture alone.
Determining inferior vena cava-tricuspid isthmus block after typical atrial flutter ablationIn typical atrial flutter, circular activation around the tricuspid ring is possible because the terminal crest prevents short-circuiting on the posterior wall, and the myocardium between the inferior vena cava (IVC) and the lower rim of the tricuspid ring is the obligatory pathway to close the circuit in the low right atrium (RA) (Figure 1). This IVC-tricuspid ring isthmus (cavotricuspid isthmus) has become the preferred target for ablation because it is the narrowest point of the circuit, it is easily accessible, and it is located far from the AV junction.
Transseptal catheterizationTransseptal catheterization through the atrial septum has become a useful skill for electrophysiologists. The challenge for a successful transseptal puncture is positioning the Brockenbrough needle at the thinnest aspect of the atrial septum, the membranous fossa ovalis, guided by either intracardiac echocardiography (ICE) or fluoroscopy.1–5 This article describes the technical aspects of performing a transseptal puncture using ICE and fluoroscopic guidance.