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Introduction: When ventricular tachycardia (VT) recurs after standard RF ablation (sRFA) some patients benefit from repeat sRFA, whereas others warrant advanced methods such as intramural needle ablation (INA). Our objectives are to assess the utility of repeat sRFA and to clarify the benefit of INA when repeat sRFA fails in patients with VT due to structural heart disease. Methods: In consecutive patients who were prospectively enrolled in a study for INA for recurrent sustained monomorphic VT despite sRFA, repeat sRFA was considered first. INA was performed during the same procedure if repeat sRFA failed or no targets for sRFA were identified. Results: Of 85 patients enrolled, acute success with repeat sRFA was achieved in 30 patients (35%), and during the 6‐month follow‐up, 87% (20/23) were free of VT hospitalization, 78% were free of any VT, and 7 were lost to follow‐up. INA was performed in 55 patients (65%) after sRFA failed, or no endocardial targets were found abolished or modified inducible VT in 35/55 patients (64%). During follow‐up, 72% (39/54) were free of VT hospitalization, 41% were free of any VT, and 1 was lost to follow‐up. Overall, 59 out of 77 (77%) patients were free of hospitalization and 52% were free of any VT. Septal‐origin VTs were more likely to need INA, whereas RV and papillary muscle VTs were less likely to require INA. Conclusions: Repeat sRFA was beneficial in 23% (18/77) of patients with recurrent sustained VT who were referred for INA. The availability of INA increased favorable outcomes to 52%. [ABSTRACT FROM AUTHOR]

Purpose: Develop a deflectable intracardiac MR imaging (ICMRI) guiding‐sheath to accelerate imaging during MR‐guided electrophysiological (EP) interventions for radiofrequency (500 kHz) ablation (RFA) of arrythmia. Requirements include imaging at three to five times surface‐coil SNR in cardiac chambers, vascular insertion, steerable‐active‐navigation into cardiac chambers, operation with ablation catheters, and safe levels of MR‐induced heating. Methods: ICMRI's 6 mm outer‐diameter (OD) metallic‐braided shaft had a 2.6 mm OD internal lumen for ablation‐catheter insertion. Miniature‐Baluns (MBaluns) on ICMRI's 1 m shaft reduced body‐coil‐induced heating. Distal section was a folded "star"‐shaped imaging‐coil mounted on an expandable frame, with an integrated miniature low‐noise‐amplifier overcoming cable losses. A handle‐activated movable‐shaft expanded imaging‐coil to 35 mm OD for imaging within cardiac‐chambers. Four MR‐tracking micro‐coils enabled navigation and motion‐compensation, assuming a tetrahedron‐shape when expanded. A second handle‐lever enabled distal‐tip deflection. ICMRI with a protruding deflectable EP catheter were used for MR‐tracked navigation and RFA using a dedicated 3D‐slicer user‐interface. ICMRI was tested at 3T and 1.5T in swine to evaluate (a) heating, (b) cardiac‐chamber access, (c) imaging field‐of‐view and SNR, and (d) intraprocedural RFA lesion monitoring. Results: The 3T and 1.5T imaging SNR demonstrated >400% SNR boost over a 4 × 4 × 4 cm3 FOV in the heart, relative to body and spine arrays. ICMRI with MBaluns met ASTM/IEC heating limits during navigation. Tip‐deflection allowed navigating ICMRI and EP catheter into atria and ventricles. Acute‐lesion long‐inversion‐time‐T1‐weighted 3D‐imaging (TWILITE) ablation‐monitoring using ICMRI required 5:30 min, half the time needed with surface arrays alone. Conclusion: ICMRI assisted EP‐catheter navigation to difficult targets and accelerated RFA monitoring. [ABSTRACT FROM AUTHOR]

This article discusses a case study involving a 70-year-old woman who experienced complications after undergoing transcatheter aortic valve replacement (TAVR). The patient presented with symptoms of blood pressure spikes and occasional dizziness, and an ECG revealed new conduction abnormalities. The patient was monitored and experienced an episode of high-grade atrioventricular block with ventricular asystole. It was determined that the administration of lidocaine, a common analgesic, may have contributed to the complications. The article highlights the potential hazards of using lidocaine as an adjunctive analgesic and emphasizes the importance of considering contraindications in patients with conduction system disease. [Extracted from the article]

Background: Catheter ablation is effective for eliminating most drug-refractory ventricular arrhythmias (VA). However, a major reason for procedural failure is arrhythmia originating deep within the myocardium where it is inaccessible to conventional endocardial or epicardial approaches. Affected patients have limited therapeutic options.Objectives: The objective of this study was to assess the safety and outcome of a novel radiofrequency ablation catheter that used an extendable/retractable 27-g needle capable of targeting deep arrhythmia (intramural) substrate.Methods: Patients who failed at least one prior catheter ablation procedure for sustained ventricular tachycardia (VT) or nonsustained VA with associated left ventricular dysfunction were enrolled at 3 centers. The target was sustained monomorphic VT in 26 patients, including 8 with recent VT storm or VT requiring intravenous medication, and 5 with incessant VA associated with ventricular dysfunction.Results: Needle ablation was performed in 31 patients (median of 2 failed prior ablation procedures; 71% nonischemic heart disease). After a median of 15 needle lesions/patient, ablation abolished at least 1 inducible VT in 19 of 26 VT patients (73%), and suppressed ambient arrhythmia in 4 of 5 nonsustained arrhythmia patients. At the 6-month follow-up, 48% of patients were free of recurrent arrhythmia and another 19% were improved. Procedure-related complications included a single pericardial effusion treated with percutaneous drainage and a left ventricular pacing lead dislodgement with no deaths.Conclusions: In patients with recurrent ventricular arrhythmias refractory to medications and conventional catheter ablation, intramural needle radiofrequency ablation offers significant arrhythmia control with an acceptable procedural risk. [ABSTRACT FROM AUTHOR]

Aims: Atrial tachycardia (AT) related to atrial fibrillation (AF) ablation frequently poses a diagnostic challenge. Downstream overdrive pacing (DOP) can be used to rapidly detect reentry and assess proximity of a pacing site to an AT circuit or focus. We hypothesized that systematic DOP using multielectrode catheters would facilitate AT mapping.Methods and results: DOP identified constant fusion when the post-pacing interval (PPI)-tachycardia cycle length (TCL) <40 ms and stimulus to adjacent upstream atrial electrogram interval >75% of TCL. Mapping was performed as follows: (i) CS DOP, (ii) DOP at left atrial (LA) roof, (iii) DOP at selected LA sites based on prior DOP attempts, and (iv) mapping and ablation at regions of fractionated electrograms in region of AT. Activation mapping was performed at operator discretion. AT diagnosis was confirmed by successful ablation or additional mapping when ablation was unsuccessful. Fifty consecutive patients with sustained AT underwent mapping of 68 ATs, of whom 42 (62%) were macroreentrant, 19 were locally reentrant (28%), and 7 (10%) were focal. AT was correctly identified with a median of three DOP attempts. All macroreentrant ATs were identified with ≤6 DOP attempts. One AT (1.6%) was terminated by DOP, and three ATs (4.8%) required activation mapping. Intracardiac concealed fusion was seen in 26 ATs (38%), each of which was successfully ablated.Conclusion: Reentry could be demonstrated in a substantial majority of AF ablation-related AT. A stepwise diagnostic approach using DOP and recognition of intracardiac concealed fusion can be used to rapidly identify and ablate reentrant AT. [ABSTRACT FROM AUTHOR]

The article projects the future of cardiovascular (CV) biomedicine in terms of cardiac arrhythmias and electrophysiology in the U.S. Topics discussed include an overview of cardiac arrhythmias, its diagnostic strategies, its lead technology and implantable devices, its ablation strategies, its pharmacological and genomic therapies, and its trends.

An editorial is presented on chemical ablation for ventricular tachycardia. Topics include the intramural ventricular arrhythmias are a major cause of catheter ablation failure and are encountered in patients with nonischemic cardiomyopathy, the myocardium is thick and an epicardial approach is often precluded by overlying fat and coronary arteries and the radiofrequency catheter‐based approaches to reaching intramural substrate have focused on increasing the depth from an epicardial electrode.

Background: Frequent premature ventricular contractions (PVCs) are often amenable to catheter ablation. However, a deep intramural focus may lead to failure due to inability of standard ablation techniques to penetrate the focus. We sought to assess the efficacy and safety of infusion needle ablation (INA) for PVCs that are refractory to standard radiofrequency ablation.Methods: Under 2 Food and Drug Administration approved protocols, INA was evaluated in patients with frequent PVCs that were refractory to standard ablation. Initial targets for ablation were selected by standard mapping techniques. INA was performed with a deflectable catheter equipped with an extendable/retractable needle at the tip that can be extended up to 12 mm into the myocardium and is capable of pacing and recording. After contrast injection for location assessment, radiofrequency ablation was performed with the needle tip using a temperature-controlled mode (maximum temperature 60 °C) with saline infusion from the needle. The primary end point was a decrease in PVC burden to <5000/24 hours at 6 months. The primary safety end point was incidence of procedure- or device-related serious adverse events.Results: At 4 centers, 35 patients (age 55.3±16.9 years, 74.2% male) underwent INA. The baseline median PVC burden was 25.4% (interquartile range, 18.4%-33.9%) and mean left ventricular ejection fraction was 37.7±12.3%. Delivering 10.3±8.0 INA lesions/patient (91% had adjunctive standard radiofrequency ablation also) resulted in acute PVC elimination in 71.4%. After a mean follow-up of 156±109 days, the primary efficacy end point was met in 73.3%. The median PVC burden decreased to 0.8% (interquartile range, 0.1%-6.0%; P<0.001). The primary safety end point occurred in 14.3% consisting of 1 (2.9%) heart block, 1 (2.9%) femoral artery dissection, and 3 (8.6%) pericardial effusions (all treated percutaneously).Conclusions: INA is effective for the elimination of frequent PVCs that are refractory to conventional ablation and is associated with an acceptable safety profile.Registration: URL: https://www.Clinicaltrials: gov; Unique identifier: NCT01791543 and NCT03204981. [ABSTRACT FROM AUTHOR]

The article presents a research study on the incidence, hospital outcome, and management of ventricular perforation which is a common complication of catheter ablation of ventricular arrhythmias. It states that patients underwent catheter ablation at a tertiary referral center. The study indicates that tamponade and ventricular perforation occurs in one percent of ventricular ablation.

Long-Term Follow-Up in Patients with Brugada Syndrome. Introduction: Risk stratification for patients with suspected Brugada syndrome (BS) remains difficult. Implantation of cardioverter-defibrillators (ICDs) in high-risk patients provides continuous long-term arrhythmia protection. Methods: Data of 33 consecutive patients undergoing ICD implantation after BS evaluation between 1995 and 2008 were reviewed. Results: There were 30 (91%) men and 3 (9%) women (46.4 ± 11.7 years). Type I Brugada was noted in 18 (54.5%), type II in 12 (36.4%) patients, and ST elevation after drug challenge in 3 patients (9.1%). Three patients had prior cardiac arrest; 70% a history of syncope; and 56% ventricular arrhythmias at the electrophysiology study. During 7.9 ± 3.6 years of follow-up, 2 patients with prior arrest received appropriate ICD shocks. None of the 30 patients without prior arrest had a sustained arrhythmia detected. ICD-related adverse effects occurred in 11 (33%) patients, including inappropriate shocks in 5 (15%). Eight patients (24%) developed 11 major device-related complications including subclavian vein thrombosis (1), pericardial effusion (1), lead fracture (2), and infection (2); in 4 patients the only complication was premature battery depletion that required early ICD replacement; however, some of these complications such as lead fractures and early battery depletion may not be specific for this patient cohort and may not repeat in the future. Conclusion: Risk stratification for patients with BS for primary prevention remains challenging. The low risk of arrhythmic events that is exceeded by ICD-related adverse effects should inform discussions with patients who do not have a prior history of cardiac arrest. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1115-1119, October 2011) [ABSTRACT FROM AUTHOR]

The article discusses a study of the electrocardiographic identification of scar-related ventricular tachycardia with a left bundle-branch block-like pattern in idiopathic ventricular arrhythmias (VA). The researchers diagnosed the scar using sinus rhythm surface electrocardiography, cardiovascular imaging and electroanatomic catheter mapping. They found a difference between the QRS morphology of scar-related and idiopathic VA.

The article highlights several case studies where combined epicardial-endocardial ablation was done on patients with hypertrophic cardiomyopathy (HCM)-related monomorphic ventricular tachycardia (MMVT). The authors report that pericardial access was achieved using the percutaneous subxyphoid method and ablation sites were identified through combined methods of activation, entrainment and pace mapping. They conclude that in some patients with HCM, combined ablation method is feasible for MMVT.

Percutaneous Epicardial Access. Introduction: There is a paucity of data on the success rates of achieving percutaneous epicardial access in different groups of patients. Methods and Results: Percutaneous epicardial access was attempted in 137 patients having 149 procedures; 19 patients had supraventricular tachycardia (SVT), 25 patients had idiopathic VT and 93 patients had scar-related ventricular tachycardia (VT). Ten patients had prior cardiac surgery. Successful epicardial access was achieved in 133 of 149 (89.3%) procedures. Access was achieved in 17 of 19 (89.5%) patients with SVT, all patients with idiopathic VT, 80 of 93 (86.0%) patients with scar-related VT and in 2 (20%) patients with prior cardiac surgery. Attempted access failed in 16 patients; 8 had prior cardiac surgery and 3 had prior pericarditis. After an initial procedure, repeat access was attempted in 15 patients, 5.1 ± 5.4 months after initial epicardial mapping and ablation. Access was successful in 13 (86.7%) and failed in 2 patients who had pericarditis after their first procedure. Only 4 patients were given intrapericardial glucocorticoid at their first epicardial procedure. Prior cardiac surgery and a history of pericarditis predicted unsuccessful access (P < 0.01). Complications (9 patients) included pericardial bleeding (80–250 mL) and intraabdominal bleeding. Conclusions: In patients without prior cardiac surgery, percutaneous epicardial access can be obtained in the majority of patients. Prior cardiac surgery precludes access in the most patients and when possible adhesions may limit catheter movement. Repeat access is possible in the majority of patients without the installation of intrapericardial glucocorticoid at the first procedure. (J Cardiovasc Electrophysiol, Vol. 21, pp. 406–411, April 2010) [ABSTRACT FROM AUTHOR]

The article discusses the findings of a research study about the mechanism and prevalence of atrial arrhythmias (AA) after lung transplantation. The study showed that the presence of AA after cardiothoracic surgery was common. It suggested whether the late AA could be prevented by additional surgical or ablation lines due to the rare appearance of atrial fibrillation (AF).

Catheter ablation for ventricular tachycardia (VT) is becoming an essential component of the successful management of patients with structural heart disease and refractory ventricular arrhythmias. Despite detailed mapping and ablation from the endocardium, nearly a third of VT circuits remain inaccessible. Pericardial access has improved our ability to address these resistant VTs. Adhesions after cardiac surgery can impede access, necessitating a direct surgical approach to the pericardial space. Potential risks include risk of injury to an epicardial coronary artery, the phrenic nerve, subdiaphragmatic vessels, and right ventricle. We describe the indications for and approach to catheter ablation of VT for the pericardial space. [ABSTRACT FROM AUTHOR]

Ventricular tachycardia (VT), which most commonly occurs in patients with structural heart disease, can be associated with an increased risk of sudden death. The most common cause of ventricular fibrillation is acute coronary ischemia, whereas a myocardial scar from prior infarct is the most common cause of sustained monomorphic VT in patients with structural heart disease. More benign forms of idiopathic VT can also occur in the absence of structural heart disease. Treatment of VT involves both emergent management and prevention of recurrence with medical and device therapy. Appropriately selected patients who have experienced VT or those who are at risk of VT may be candidates for an implantable cardioverter-defibrillator. The left ventricular ejection fraction is most frequently used to stratify patients with either ischemic or nonischemic cardiomyopathy who are at risk of sudden death and may be candidates for a prophylactic defibrillator. Catheter ablation may also be an option for appropriately selected patients with many forms of VT. This article discusses the etiologies and management of VT and its association with sudden death. [ABSTRACT FROM AUTHOR]

Background: The prognostic importance of exercise-induced ventricular arrhythmia (EIVA) may be confounded by the presence of lower-risk idiopathic right ventricular outflow tract arrhythmias with left bundle-branch block (LBBB) morphology. Objective: To determine whether right bundle-branch block (RBBB)-morphology EIVA was associated with increased mortality. Design: Retrospective cohort. Setting: Academic medical center. Patients: 585 unique patients with EIVA and 2340 patients without EIVA, matched by age, sex, and risk factor, who were referred for exercise testing in an academic medical center. Measurements: Deaths and ischemia and infarction found on perfusion scan. Results: During a mean follow-up of 24 months (SD, 13), 31 deaths occurred in the EIVA group compared with 43 deaths in the group without EIVA (5.3% vs. 1.8%; P < 0.001). Worse survival in patients with RBBB-morphology or multiple-morphology EIVA (6.9%) than in patients without EIVA caused this difference. Patients with LBBB-morphology EIVAs had a mortality rate (2.5%) similar to that of patients without EIVA (P = 0.93, log-rank test). Among patients without known atherosclerotic coronary artery disease, any RBBB-morphology EIVA was associated with death (hazard ratio, 2.73 [95% CI, 1.78 to 4.13]; P< 0.001), but LBBB-morphology EIVA was not (hazard ratio, 0.82 [CI, 0.18 to 2.04]; P= 0.72). Limitations: Not all LBBB-morphology EIVA can be dismissed, and not all RBBB-morphology EIVA is high risk. Further evaluation of patients for structural heart disease was clinically driven, not protocol- driven. Conclusion: Right bundle-branch block- or multiple-morphology EIVA is associated with increased mortality. Inclusion of patients with isolated LBBB-morphology EIVA, which often is idiopathic, may contribute to differences in the prognostic importance of EIVA in previous studies. [ABSTRACT FROM AUTHOR]

Catheter ablation is an important therapeutic option for controlling recurrent ventricular arrhythmias in patients with heart disease. Although implantable defibrillators are generally first line therapy in this patient population, a substantial number of patients require additional therapy with either antiarrhythmic drugs, ablation, or both. Studies of mapping and ablation have produced further insights into pathophysiologic mechanisms of these arrhythmias, which are now well characterized. The majority is due to reentry through regions of ventricular scar. Methods for identifying scar based on electrogram characteristics now allow arrhythmogenic areas to be targeted for ablation during stable sinus rhythm, such that ablation is often an option even when multiple and unstable ventricular tachycardia are present. Ablation failure can also be due to anatomical obstacles; however, methods for accessing the pericardial space for mapping and ablation and technological progress can be expected to further improve its efficacy. [ABSTRACT FROM AUTHOR]

The precise techniques employed in the electrophysiology laboratory influence the nature of the electrograms that are recorded during mapping procedures. Unipolar recordings that are minimally filtered can be useful for mapping focal arrhythmia sources, but have substantial far-field signal that can obscure low-amplitude signals of interest in abnormal regions. Bipolar recordings are standard in most laboratories because rejection of far-field signal facilitates identification of local potentials in abnormal areas, but the signal of interest can be beneath either recording electrode and far-field signals do occur. Simultaneously obtained unipolar recordings are a useful adjunct to bipolar recordings in some situations. High pass filtering and digital sampling also influence electrogram characteristics. High pass filtering of unipolar recordings can be useful to reduce far-field components, but limits inferences from electrogram morphology. [ABSTRACT FROM AUTHOR]

Optimizing RF Output. Cooled RF ablation catheters increase lesion size and facilitate ablation compared to standard RF ablation catheters. Cooling the ablation electrode increases the disparity between tissue temperature and electrode temperature, making use of temperature for guiding power application during ablation of less certain value. Appropriate energy titration is important, however, to produce large lesions, while avoiding overheating of tissue with steam formation leading to“pops.” In addition to power, the rate of irrigant flow can be controlled. Electrode–tissue contact and orientation and the cooling effect of blood flow around the electrode and within the tissue are not as easily adjusted and also influence tissue heating. In addition to electrode temperature, a decrease in impedance, bubble formation detected by intracardiac ultrasound, and evidence of tissue heating from an effect on recorded electrograms or the arrhythmia can be used to guide ablation energy. Guidelines for adjusting power delivery and avoiding“pops” and coagulum formation are suggested.(J Cardiovasc Electrophysiol, Vol. 15, pp. S24-S27, Suppl. 1, October 2004) [ABSTRACT FROM AUTHOR]

Objective: To study the safety, efficacy, and mapping utility of a new cryoablation catheter.Background: The CryoCath Technologies Freezor catheter has been used successfully for cryoablation of supraventricular tachycardia (SVT), but has not been evaluated in a large clinical trial.Methods: A multicenter clinical trial to evaluate the safety, efficacy, and cryomapping utility of this cryoablation catheter was conducted in 166 subjects. The target of ablation was the slow pathway in patients with SVT due to AV nodal reentry (AVNRT, n = 103), an accessory pathway in patients with AV reentrant SVT (AVRT, n = 51) and the AV junction in patients with atrial fibrillation (AF, n = 12).Results: Acute procedural success (APS) was achieved in 83% of the overall group (95% CI, 76% to 88%). APS in the AVNRT group was 91% (98.3% CI, 82% to 97%), compared to 69% for AVRT (98.3% CI, 51% to 84%) and 67% for AF (98.3% CI, 29% to 93%), a highly significant difference (P < .001 by stepwise logistic regression). In patients with APS, long-term success after 6 months was 91% overall (95% CI, 86% to 96%) and 94% for AVNRT subjects (98.3% CI, 87% to 100%). None of the AVNRT or AVRT subjects required a permanent pacemaker. Cryomapping successfully identified ablation targets in 64% of patients in whom it was attempted. The electrophysiologic effects of cryomapping were completely reversible within minutes in 94% of such attempts.Conclusions: Catheter cryoablation of SVT is a safe alternative to RF ablation and is clinically effective in patients with AVNRT. Cryomapping can reversibly identify targets for ablation and can help minimize the risk of inadvertent AV block during ablation. [ABSTRACT FROM AUTHOR]

SAPP, J.L., et al.: Ablation Lesion Size Correlates with Pacing Threshold: A Physiological Basis for Use of Pacing to Assess Ablation Lesions. The virtual electrode model predicts that pacing stimulus strength should reflect proximity of the pacing electrode to excitable myocardium, allowing pacing threshold to assess radiofrequency (RF) ablation lesions and unexcitable scar. The purpose of this study is to correlate RF lesion size with pacing threshold and electrogram (EG) amplitude change at the ablation site. In four swine (32–58 kg, 20 ventricular RF lesions were created using a 4-mm tip electrode catheters under fluoroscopic and electroanatomic guidance. Unipolar pacing threshold and bipolar and unipolar EG amplitude were measured before and after ablation and compared with lesion size measured in the fixed, serially sectioned tissue. Lesion diameter ranged from 6.4 to 19 mm and volume ranged from 29 to 1920 mm. Ablation increased the pacing threshold by 320%, from 0.9 ± 0.3 to 3.6 ± 2.6 mA, P < 0.001. The change in pacing threshold correlated with lesion volume R = 0.88, P < 0.001). Linear regression predicts that lesion volume (mm3) = 160 X rise in pacing threshold + 13. Ablation reduced peak to peak bipolar EG amplitude by 56%, from 2.5 ± 2.0 mV to 1.1 ± 0.6 mV (P = 0.005). Unipolar EG amplitude diminished by only 22% from 4.0 ± 1.6 to 3.2 ± 0.9 mV postablation (P = 0.005). The correlations of lesion volume with change in either bipolar R = 0.14, P = 0.6) or unipolar R = 0.18, P = 0.6) EG amplitude were poor. Pacing threshold correlates with RF ablation lesion size, consistent with the virtual electrode model. In normal myocardium, change in pacing threshold is likely to be a better marker of lesion size than electrogram amplitude. (PACE 2004; 27:933–937) [ABSTRACT FROM AUTHOR]

Epicardial-Endocardial Approach to IST Ablation. A combined epicardial-endocardial approach to ablation of inappropriate sinus tachycardia in a highly symptomatic patient who failed to respond to medical therapy and endocardial ablation is described. The anatomy and physiology of the sinus node is discussed, providing a basis for performing this procedure. This case provides an additional therapeutic option for a condition that often is difficult to manage. (J Cardiovasc Electrophysiol, Vol. 15, pp. 237-240, February 2004) [ABSTRACT FROM AUTHOR]

Arrhythmias continue to contribute significantly to morbidity and mortality in heart failure. Implantable defibrillators have assumed an increasingly important role in preventing sudden death and are recommended for patients who have been resuscitated from cardiac arrest, have unexplained syncope, or exhibit inducible ventricular tachycardia in the setting of prior myocardial infarction. The extension of survival conferred by implantable defibrillators is likely to be limited in patients with advanced heart failure. Ongoing trials will help define the use of these devices in heart failure populations, in whom atrial fibrillation is common and rate control and anti-coagulation are of major importance. Among pharmaceutical options, amiodarone and dofetilide are the major agents for maintenance of sinus rhythm. The complexity of coexistent heart failure and arrhythmia management warrants close collaboration between heart failure and arrhythmia specialists. [ABSTRACT FROM AUTHOR]

Introduction Methods and Results Conclusion Catheter‐based radiofrequency (RF) ablation is generally regarded as the standard approach for patients with ventricular tachycardia (VT) refractory to antiarrhythmic drug therapy and may be considered as a first‐line approach when there is a preference to avoid these agents. Patients with a history of cardiac surgery may have VT substrate inaccessible to catheter ablation due to intervening prosthetic materials or scar.This article describes a 55‐year‐old patient with a history of surgically repaired subvalvular aortic stenosis and subsequent valve‐sparing root replacement who presented with sustained VT. After RF ablation failed due to VT substrate “guarded” by graft material, retrograde coronary venous ethanol ablation (RCVEA) was employed to successfully treat the clinical VT.RCVEA ablation can be useful for treating VT when conventional ablation is limited by inaccessible substrate due to prior cardiac surgery. [ABSTRACT FROM AUTHOR]

Discusses how survivors of myocardial infarction are at risk for ventricular arrhythmias and sudden death. Physicians who must decide whether to refer patients to specialists for arrhythmia assessment and therapy; Complexity of decision; Study which models the potential impact of current arrhythmia detection and management strategies on mortality in survivors of myocardial infarction with reduced left ventricular function who are managed in a contemporary manner.

Ventricular arrhythmias remain the leading cause of death from coronary artery disease. This review summarizes current thinking in several areas relating to the pathophysiology, prognosis, and therapy of ventricular arrhythmias associated with acute and chronic coronary artery disease syndromes. The experimental basis of arrhythmias in the setting of acute myocardial ischemia and chronic myocardial infarction is described, stressing the important pathophysiologic differences between these two conditions. The effects of the autonomic nervous system as a key modulator of ischemic arrhythmogenesis are discussed. Insights, derived from endocardial mapping studies, into the nature of ventricular tachycardia in humans with chronic myocardial infarction are described, including implications for risk stratification and therapy to prevent arrhythmia recurrence. Current therapeutic principles are discussed in the management of ventricular arrhythmias associated with coronary artery disease, including pharmacologic approaches, surgical and catheter ablation, and automatic implantable cardioverting and defibrillating devices. [ABSTRACT FROM AUTHOR]

Monomorphic ventricular tachycardias associated with regions of scar are most commonly due to reentry. Catheter based techniques have recently been described for mapping of reentry circuits. Fluoroscopic methods have obvious limitations when attempting to map large ventricular reentry circuit and localize target-sites of radiofrequency ablation. Three-dimensional right ventricular endocardial mapping was performed in a 38-year-old patient with ventricular tachycardia 28 years after surgical correction of tetralogy of Fallot by using the CARTO electroanatomical system. The map of electrogram voltage showed low amplitude electrograms over the anterior wall of the right ventricle extending into the right ventricular outflow tract, consistent with the location of the ventriculotomy scar. Recording of local activation time was combined with entrainment mapping to define the rnacroreentrant circuit during ventricular tachycardia. Since the activation propagated through a broad path around the right ventriculotomy scar, ablation was performed by creating a line of block, which was facilitated by tagging of the lesion sites on the endocardial activation map. Large ventricular reentry circuits can be identified and interrupted by creation of a line of block to interrupt a broad path. A practical approach to mapping combining analysis of electrogram voltage, activation sequence, and entrainment is presented. [ABSTRACT FROM AUTHOR]

This study was designed to assess the effects of isoflurane (ISO) on the electrophysiological properties of the accessory pathway, atrium, ventricle, and AV node in children with the Wolff-Parkinson-White (WPW) syndrome. The results of programmed electrical stimulation were analyzed in 51 patients (4 months to 17 years of age) with WPW. The study population was divided into two groups. Twenty-seven patients received local anesthesia and intramuscular injection of meperidine, promethazine, and chlorpromazine (MPC group). Twenty-four patients received general anesthesia with ISO inhalation (ISO group). We compared the antegrade effective refractory period of the accessory pathway (antegrade APERP), ventricular effective refractory period (VERP), atrial effective refractory period (AERP), AH interval, and cycle length of circus movement tachycardia (CMT-CL) in 12 pairs of age and sex matched patients selected from the MPC and ISO groups. Of the 12 pairs of age and sex matched patients, antegrade APERP in patients who received ISO (299 ±17 ms, mean ± SEM) was significantly longer as compared with matched patients in the MPC group (262 ± 5 ms, P < 0.025). The VERP and AERP in patients from the ISO group were significantly prolonged compared with the MPC patients (239 ±7 vs 210 ± 8 ms, P < 0.025, and 228 ± 11 vs 180 ± 6 ms, P < 0.01, respectively). There was no significant difference in the AH interval or CMT-CL between the two subgroups. Thus, ISO prolongs the antegrade APERPs as well as the effective refractory periods of atrial and ventricular muscle in children with WPW, while the AH interval and CMT-CL appear to be unaffected. Care must be taken in interpreting measurements of the antegrade APERP made in patients under general anesthesia for RE ablation of accessory pathways. [ABSTRACT FROM AUTHOR]

Introduction: Radiofrequency (RF) ablation of ventricular tachycardia (VT) late after myocardial infarction may be difficult due to characteristics of the infarct containing the reentry circuit. RF lesions in these infarcts in humans have not been characterized. Methods and Results: Catheter mapping and ablation of VT originating from an anterior wall infarct was performed 8 days and again 12 hours prior to death. Pacing identified a region of abnormal conduction where RF ablation terminated VT. This region contained strips of myocytes sandwiched between endocardial fibrosis and dense scar. RF lesions ranged from 2 × 2 mm to 5 × 10 mm and were up to 3 mm in depth. Acute lesions showed superficial thrombus and early coagulation necrosis without inflammation. Older lesions showed coagulation necrosis, sparse neutrophil infiltrate, minimal granulation tissue, hemorrhage, and mixed inflammatory infiltrate along the lumen without re-endothelialization. Conclusion: In this patient, RF lesions had sufficient depth but not width to interrupt the thin, but potentially broad, sheets of myocytes in the reentry circuit. In thinned areas, RF lesions can extend to the epicardium. Selecting sites with abnormal electrograms confines RF lesions to the infarct region. Inflammation and hemorrhage could conceivably cause delayed effects of RF. [ABSTRACT FROM AUTHOR]

Discusses the evidence that sympathetic stimulation facilitates and parasympathetic stimulation reduces the risk of fatal arrhythmias during acute myocardial ischemia as well as the risk of ventricular arrhythmias arising from a chronic infarct scar late after infarction. Risk facing patients who survive the acute phase of myocardial infarction; Association of heart rate variability with sudden death risk; Information on a randomized trial of a surgical approach to protect the heart from the electrophysiologic consequences of sympathetic stimulation.

During entrainment or resetting of ventricular tachycardia, the distance a stimulated antidromic wave front propagates determines the degree of QRS fusion observed. Determinants of antidromic wave front propagation distance during stimulation at reentry circuit sites were studied in computer simulations of figure eight reentry circuits. When not limited by refractory tissue, antidromic propagation distance depended on the stimulus timing, the conduction velocity in the antidromic direction away from the stimulus site, and the time available for propagation before collision with a returning orthodromic wave front. The latter was determined by the conduction time through the circuit in the orthodromic direction from the stimulus site. Faster conduction from the stimulus site in the orthodromic direction relative to the antidromic direction diminished antidromic wave front propagation distance. Consequently, in circuits with heterogeneous conduction velocities, antidromic propagation distance was dependent on the location of the stimulus site. Stimulation in slow areas limited antidromic propagation distance, although increasing stimulus prematurity increased antidromic propagation distance markedly if the antidromic wave front reached faster tissue. These findings explain the ability of rapid or premature stimuli to entrain or reset tachycardia without producing detectable antidromic wave front effects (QRS fusion) on the surface electrocardiogram when the stimulation site is located centrally within slowly conducting areas in the reentry circuit. However, greater antidromic propagation occurs with stimulation at or near more rapidly conducting sites increasing the likelihood that antidromic effects will be seen on the surface electrocardiogram. [ABSTRACT FROM AUTHOR]

This article presents the case study of a 58-year-old man was referred for catheter ablation of recurrent symptomatic tachycardias. The tests found three possibilities which include a narrow and wide complex tachycardia (WCT) that are related to single mechanism, a preexcited tachycardia with ventricular activation over an accessory pathway, or a supraventricular tachycardia inducing ventricular tachycardia.

The article describes the case of a 33-year-old woman with a 25-year history of recurrent palpitations (RP) in Boston, Massachusetts. The atrioventricular relationship and the earliest atrial activation was recorded during inducible regular long RP interval supraventricular tachycardia (SVT). The differential diagnosis of this narrow QRS complex and long RP interval SVT includes left atrial tachycardia and orthodromic atrioventricular reciprocating tachycardia.

The article provides information on the case study involving a 37-year-old woman who was explored for electrophysiologic study for paroxysmal supraventricular tachycardia. Clinical investigations conducted revealed that after slow pathway ablation and during isoproterenol infusion, narrow complex tachycardia occurred. Discussion on the mechanism of the tachycardia is presented.

As the population of patients with implanted defibrillators has grown, an increasing number of patients nonischemic cardiomyopathies are requiring therapy to reduce ventricular arrhythmias. Most of these arrhythmias are related to areas of ventricular scar. Although the pathophysiology of scar development is not well understood in these diseases, advances in cardiac imaging and mapping are better characterizing the scar locations that give rise to the arrhythmias. Here, we review the pathophysiologic and electrocardiographic correlations that inform ablation strategies for ventricular tachycardia in these diseases. [ABSTRACT FROM AUTHOR]

We report the first clinical application of electrocardiographic imaging (ECGI), a new, noninvasive imaging modality for arrhythmias, in an athlete with focal ventricular tachycardia (VT) originating from a left ventricular (LV) diverticulum. A reconstructed map of the epicardial activation sequence during a single premature ventricular complex (PVC) of an identical QRS morphology to the clinical VT, generated from 224-electrode body surface ECGs and a chest CT (ECGI), localized the PVC to the site of the diverticulum. This correlated with subsequent maps obtained using standard techniques. We describe the first case that used ECGI to guide diagnosis and therapy of a clinical tachyarrhythmia. [Copyright &y& Elsevier]

This article focuses on a case study related to electrophysiology. A 52-year-old woman underwent electrophysiologic .study for recurrent supraventricular tachycardia. Programmed stimulation from the right ventricle repeatedly induced atrioventricular reentrant tachycardia (AVRT) using a concealed leftsided accessory pathway. The explanation for the observed shortening of VA interval during the successful RF application is that before pathway block occurred, retrograde conduction was over the accessory pathway, and after pathway block occured retrograde conduction was over the more rapidly conducting AV node.

When VT recurs, particularly with ICD shocks, it is reasonable to consider catheter ablation at that time to prevent further VT, particularly for patients with ischemic heart disease or arrhythmogenic right ventricular cardiomyopathy. Keywords: Editorials; cardiomyopathy; radiofrequency catheter ablation; ventricular tachycardia EN Editorials cardiomyopathy radiofrequency catheter ablation ventricular tachycardia 1850 1852 3 06/17/22 20220621 NES 220621 Is my patient likely to benefit from this therapy?. [Extracted from the article]

Supplemental Digital Content is available in the text. [ABSTRACT FROM AUTHOR]

In patients with structural heart disease, slow VTs are easier to initiate and more likely to occur spontaneously than faster VTs. All patients had VT sufficiently severe to warrant, but disease not so severe as to preclude, a catheter ablation procedure. From a cohort of 215 patients and >176 VT s, only 53 VT s from 49 patients had a complete reentry circuit defined on either the epicardial or endocardial surface of the heart. If the mean conduction velocity through the circuit is slowed to 0.3 m/s, the path length would be 9 cm (a diameter of a little © 2021 American Heart Association, Inc. https://www.ahajournals.org/journal/circ Circulation Kanagasundram et al VT Cycle Length EDITORIAL January 19, 2021 Circulation. [Extracted from the article]

The author focuses on the topic of sudden arrhythmic death syndrome. The most common mechanisms of sudden death are ventricular arrhythmias precipitating cardiac arrest. Several inherited arrhythmogenic syndromes that cause sudden death have been characterized and some are associated with structural heart disease, such as hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy.

The article offers information on atrial fibrillation, regarded as the most common arrythmia, affecting around three million adults in the U.S.