Henry H. Hsia

Characterization of Endocardial Electrophysiological Substrate in Patients With Nonischemic Cardiomyopathy and Monomorphic Ventricular Tachycardia

Background—Although catheter mapping has been used to define the endocardial electrogram characteristics in patients with ventricular tachycardia (VT) and coronary disease, characterization of the electrophysiological substrate in patients with VT and nonischemic cardiomyopathy is limited. Methods and Results—Left ventricular endocardial electroanatomical mapping was performed in 19 patients with nonischemic cardiomyopathy and monomorphic VT with an average of 178±83 sites per chamber mapped. Abnormal bipolar electrogram was defined as endocardial voltage signal amplitude of <1.8 mV. The extent and location of abnormal endocardium was estimated by measuring areas of abnormal electrogram recordings from 3D voltage maps. The origin of VT was approximated by identifying sites of entrainment with concealed fusion or early presystolic activity and/or by pace mapping. Abnormal electrograms were recorded over a 41±28 cm2 area that represented 20±12% of total endocardial surface. The majority of patients (14/19 patients) had only a modest area (<25%) of endocardial abnormality. All patients had abnormal low-voltage endocardial areas located near the ventricular base in the perivalvular region. There were 3±1 VT morphologies per patient. The majority (88%) of the 57 mapped VTs originated from the ventricular base, corresponding to regions with abnormal endocardial electrograms. Conclusions—Electroanatomical mapping in patients with monomorphic VT and nonischemic cardiomyopathy typically demonstrates a modest-sized basal area of endocardial electrogram abnormalities. The VT site of origin corresponds to these basal electrogram abnormalities. These findings have important implications regarding strategies for VT ablation in this setting.

Electroanatomic Substrate and Outcome of Catheter Ablative Therapy for Ventricular Tachycardia in Setting of Right Ventricular Cardiomyopathy

Background—To gain insight into the pathogenesis of right ventricular (RV) cardiomyopathy and ventricular tachycardia (VT), we determined the clinical and electroanatomic characteristics and outcome of ablative therapy in consecutive patients with (1) RV dilatation, (2) multiple left bundle-branch block (LBBB)–type VTs, and (3) an abnormal endocardial substrate defined by contiguous electrogram abnormalities. Methods and Results—All 21 patients had detailed RV bipolar electrogram voltage mapping. Eighteen patients had simultaneous left ventricular (LV) mapping, including all 4 patients with right bundle-branch block (RBBB) VT. VT was ablated in 19 patients by use of focal and/or linear lesions with irrigated-tip catheters in 10 of 19 patients. Eighteen patients were men, age 47±18 years, and none had a family history of RV dysplasia. RV volume was 223±89 cm3. Electrogram abnormalities extended from perivalvular tricuspid valves (5 patients), pulmonic valves (6 patients), or both valves (10 patients). Electrogram abnormalities always involved free wall, spared the apex, and included the septum in 15 patients (71%). The area of abnormality was 55±37 cm2 (range, 12 to 130 cm2) and represented 34±19% of the RV. In 52 of 66 LBBB VTs, the origin was from the RV perivalvular region. LV perivalvular low-voltage areas noted in 5 patients were associated with a RBBB VT origin. No VT recurred after ablation in 17 patients (89%) during 27±22 months. Conclusions—In patients with RV cardiomyopathy and VT, (1) perivalvular electrogram abnormalities represent the commonly identified substrate and source of most VT, (2) LV perivalvular endocardial electrogram abnormalities and VT can occasionally be identified, and (3) aggressive ablative therapy provides long-term VT control.

Increased intensity of anticoagulation may reduce risk of thrombus during atrial fibrillation ablation procedures in patients with spontaneous echo contrast.

Introducton:A 10% incidence of left atrial (LA) thrombus formation has been detected using intracardiac echocardiography (ICE) imaging monitoring during LA ablation for atrial fibrillation (AF). The aim of this study was to determine if the intensity of anticoagulation reduces LA thrombus formation during pulmonary vein isolation procedure in patients with AF and spontaneous echo contrast (SEC).

Right Bundle-Branch Block Ventricular Tachycardias Septal Versus Lateral Ventricular Origin Based on Activation Time to the Right Ventricular Apex

Background—Identifying the septal versus lateral site of origin of ventricular tachycardia (VT) with a right bundle-branch block (RBBB)–type pattern and an R-S ratio >1 in lead V1 is difficult with the 12-lead ECG, especially in patients with prior apical infarction. Methods and Results—We prospectively evaluated 58 patients with VT. Sixteen patients had apical infarcts (group 1), 29 had nonapical infarcts (group 2), and 13 had no heart disease (group 3). QRS complex onset to activation at the right ventricular apex (stim-RVA) was measured during left ventricular (LV) apical septal and lateral pacing, and 47 RBBB-type VTs (QRS-RVA) were localized to the septal or lateral apex by using entrainment techniques. Pacing and VT site of origin were confirmed by electroanatomic mapping. The stim-RVA time was 59±16 ms for septal versus 187±24 ms for lateral sites in group 1, P<0.001; 70±14 ms for septal versus 169±19 ms for lateral sites in group 2, P<0.001; and 42±15 ms for septal versus 86±16 ms for lateral sites in group 3, P<0.005. The QRS-RVA time was 50±13 ms for apical septal VTs versus 178±21 ms for lateral VTs in group 1, P<0.001; 71±17 ms for apical septal versus 157±20 ms for lateral VTs in group 2, P<0.001; and 32±12 ms for septal versus 71±16 ms for lateral VTs in group 3, P<0.01. Conclusions—The QRS-RVA differs for the VT site of origin from the LV septal versus lateral apex. These data prove useful in rapidly regionalizing the VT site of origin with a V1 R-S ratio >1, particularly in instances of an apical infarct, where surface ECG distinctions are less identifiable.

Ventricular Tachycardia Storm After Initiation of Biventricular Pacing: Incidence, Clinical Characteristics, Management, and Outcome

Introduction: Cardiac resynchronization therapy (CRT) or biventricular pacing (BVP) is becoming an important treatment option in patients with severe congestive heart failure (CHF) and electrical dyssynchrony. When combined with implantable cardioverter‐defibrillator (ICD) therapy, cardiac resynchronization therapy with a defibrillator (CRT‐D) has been shown to improve quality of life, functional class, and, most recently, survival. However, left ventricular (LV) stimulation in the form of BVP in patients at high risk of developing ventricular tachyarrhythmias has raised concerns that BVP may be proarrhythmic. We describe the incidence, clinical characteristics, and management in a series of patients who developed ventricular tachycardia storm (VTS) after initiation of BVP.

Comparison of Cool Tip Versus 8-mm Tip Catheter in Achieving Electrical Isolation of Pulmonary Veins for Long-Term Control of Atrial Fibrillation: A Prospective Randomized Pilot Study

Objective: To compare safety and efficacy of 8‐mm versus cooled tip catheter in achieving electrical isolation (EI) of pulmonary veins (PV) for long‐term control of atrial fibrillation (AF).

Safety and outcomes of cryoablation for ventricular tachyarrhythmias: results from a multicenter experience.

BACKGROUND Catheter ablation of ventricular arrhythmias (VAs) with cryoenergy has not been widely reported. OBJECTIVE The purpose of this study was to assess the feasibility and safety of cryoablation for VA. METHODS Cases where cryoablation of VA was attempted as the initial strategy or was considered to prevent potential damage to other structures such as the coronary arteries, phrenic nerve, and His bundle were collected. Thirty-three patients with either normal heart or structural heart disease undergoing VA ablation using cryoenergy at six different institutions were enrolled in the study. Epicardial access was obtained when appropriate. RESULTS Fifteen patients (7 men) underwent endocardial ablation, 13 (9 men) epicardial ablation (from the coronary sinus in 7), and 5 (2 men) aortic cusp ablation. Mean age was 54 ± 8 years, and ejection fraction was 45% ± 5%. In 15 (45%) patients, VAs were successfully ablated, whereas cryoablation was unsuccessful in the remaining 18 (55%) patients. Cryoablation was successful in all parahisian cases (100%). In three patients, epicardial cryoablation was successful after several failed attempts with open irrigated catheter. An aortic dissection occurred during catheter placement in the aortic cusp. At follow-up of 24 ± 5 months, all patients with acute success were free from clinical VA. CONCLUSION Use of cryoenergy for ablation of VA has excellent success for arrhythmias near the His bundle; however, success rates at other sites appear less favorable. Cryoablation may be considered as an alternative approach for reducing complications during ablation of VAs originating from sites close to other relevant cardiac structures (conduction system, coronary arteries, phrenic nerve) and, in rare cases, could be used epicardially when radiofrequency energy applications have failed.

Influence of Age on Perioperative Complications Among Patients Undergoing Implantable Cardioverter-Defibrillators for Primary Prevention in the United States

Background— The majority of current implantable cardioverter-defibrillator (ICD) recipients are significantly older than those in the ICD trials. Data on periprocedural complications among the elderly are insufficient. We evaluated the influence of age on perioperative complications among primary prevention ICD recipients in the United States. Methods and Results— Using the National Cardiovascular Datas ICD Registry, we identified 150 264 primary prevention patients who received ICDs from January 2006 to December 2008. The primary end point was any adverse event or in-hospital mortality. Secondary end points included major adverse events, minor adverse events, and length of stay. Of 150 264 patients, 61% (n=91 863) were 65 years and older. A higher proportion of patients ≥65 years had diabetes, congestive heart failure, atrial fibrillation, renal disease, and coronary artery disease. Approximately 3.4% of the entire cohort had any complication, including death, after ICD implant. Any adverse event or death occurred in 2.8% of patients under 65 years old; 3.1% of 65- to 69-year-olds; 3.5% of 70- to 74-year-olds; 3.9% of 75- to 79-year-olds, 4.5% of 80- to 84-year-olds; and 4.5% of patients 85 years and older. After adjustment for clinical covariates, multivariate analysis found an increased odds of any adverse event or death among 75- to 79-year-olds (1.14 [95% confidence interval, 1.03 to 1.25], 80-to 84-year-olds (1.22 [95% confidence interval, 1.10 to 1.36], and patients 85 years and older (1.15 [95% confidence interval, 1.01 to 1.32], compared with patients under 65 years old. Conclusions— Older patients had a modestly increased—but acceptably safe—risk of periprocedural complications and in-hospital mortality, driven mostly by increased comorbidity.

Ventricular tachycardia/ventricular fibrillation ablation in the setting of ischemic heart disease.

Recurrent ventricular tachycardia (VT) in the setting of coronary artery disease is frequently a life‐threatening electrophysiologic emergency. Even in patients with an implantable defibrillator, recurrent VT is frequently accompanied by repeated and disabling shock therapy. Catheter ablative therapy offers the ability to provide immediate control of recurrent VT. Long‐term elimination of VT should be anticipated in most patients. This article reviews the strategies, tools, techniques, and expected outcome for catheter ablation of stable and unstable ventricular arrhythmias in the setting ischemic heart disease.

Early postoperative increase in defibrillation threshold with nonthoracotomy system in humans.

The stability of the defibrillation threshold (DFT) early after implantation of an implantable cardioverter defibrillator was evaluated in 15 patients. All but one patient had a three lead nonthoracotomy system using a subcutaneous patch, a right ventricular endocardial lead, and a lead in coronary sinus (n = 5) or superior vena cava (n = 9). Shocks were delivered using simultaneous in nine, sequential in three, and single pathway (coronary sinus not used) in one patient. DFTs were measured at implant (n = 15), 2–8 days postoperation (postop, n = 15), and 4–6 weeks later (n = 8). The DFT was defined as the lowest energy shock that resulted in successful defibrillation. The DFT was assessed with output beginning at 18 joules or 2–4 joules above the implant DFT. All shocks were delivered in 2‐ to 4‐joule increments or decrements. DFTs were significantly higher postoperatively than DFTs at implant (22.7 ± 7.0 J vs 16.9 ± 3.9 J; P < 0.05), Eight of 15 patients had DFT determined at all three study periods. In these patients, DFT increased at postop (22.8 ± 8.3 J vs 16.4 ± 3.9 J at implant: P < 0.05) and returned to baseline at 4–6 weeks (16 ± 7.1) vs 16.4 ± 3.9 J at implant; P = N.S.). Thus, in patients with a multilead nonthoracotomy system, a DFT rise was observed early after implant. The DFT appears to return to baseline in 4–6 weeks. These results have important implications for programming energy output after implantable cardioverter defibrillator implantation.