Utility of Intracardiac Echocardiography to Guide Transseptal Catheterization for Different Electrophysiology Procedures.

"Intracardiac echocardiography (ICE) has evolved into an indispensable tool in the armamentarium of cardiac electrophysiologists not only for understanding the internal cardiac anatomy but also for establishing transseptal access and for monitoring electrophysiology procedures. ICE aids in live monitoring of every step of the procedure including early detection of complications. Access to the left atrium through transseptal catheterization is a vital step to perform atrial fibrillation and accessory pathway ablations, ablation of left ventricular tachycardias, left atrial appendage closures, left ventricular endocardial electrode implantations for cardiac resynchronization therapies, and for selectively sampling the regions of interest during endomyocardial biopsies."

Hypertrophic cardiomyopathy. / Miocardiopatía hipertrófica.

Hypertrophic cardiomyopathy is the most common inherited cardiovascular disease. It is characterized by increased ventricular wall thickness and is highly complex due to its heterogeneous clinical presentation, several phenotypes, large number of associated causal mutations and broad spectrum of complications. It is caused by mutations in sarcomeric proteins, which are identified in up to 60% of cases of the disease. Clinical manifestations of Hypertrophic Cardiomyopathy include shortness of breath, chest pain, palpitations and syncope, which are related to the onset of diastolic dysfunction, left ventricular outflow tract obstruction, ischemia, atrial fibrillation and abnormal vascular responses. It is associated with an increased risk of sudden cardiac death, heart failure and thromboembolic events. In this article, we discuss the diagnostic and therapeutic aspects of this disease.

Radiofrequency-assisted transseptal perforation for electrophysiology procedures in children and adults with repaired congenital heart disease.

BACKGROUND: Patients with congenital heart disease carry a high burden of arrhythmias and may pose special challenges when these arrhythmias are addressed invasively. We sought to describe our early experience with radiofrequency (RF) needle transseptal perforation to facilitate ablation procedures in this population. METHODS: Retrospective chart review to identify all cases of attempted transseptal access with a commercial RF needle at Children's Hospital Boston between February 2007 and January 2010. RESULTS: A total of 10 patients had attempted RF transseptal perforation. Median age was 27 years. Five patients had undergone atrial switch procedures (Mustard/Senning), four had undergone Fontan operations, and one had atrial septal defect repair. The indication for left atrial access was mapping/ablation of atrial flutter in nine cases, and left-sided accessory pathway in one case. The RF needle was chosen primarily in eight of 10 cases, whereas in the remaining two cases RF was used only after failed attempts with a conventional Brockenbrough needle. Septal material was atrial muscle in five cases, pericardium in three, and synthetic fabric in two. In nine of 10 patients, RF transseptal perforation was successful, including both patients in whom a conventional needle had failed. There were no clinically significant complications. CONCLUSIONS: RF transseptal perforation can be an effective method of obtaining left atrial access for electrophysiologic procedures in patients with complex congenital heart disease, including cases where a conventional Brockenbrough needle has failed.

Added value of transoesophageal echocardiography during transseptal puncture performed by inexperienced operators.

AIMS: Transseptal puncture (TP) appears to be safe in experienced hands; however, it can be associated with life-threatening complications. The aim of our study was to demonstrate the added value of routine use of transoesophageal echocardiography (TEE) for the correct positioning of the transseptal system in the fossa ovalis, thus potentially preventing complications during fluoroscopy-guided TP performed by inexperienced operators. METHODS AND RESULTS: Two hundred and five patients undergoing pulmonary vein isolation procedure (PVI) for drug-resistant paroxysmal or persistent atrial fibrillation were prospectively included. When the operator (initially blinded to TEE) assumed that the transseptal system was in a correct position according to fluoroscopical landmarks, the latter was then checked with TEE unblinding the physician. If necessary, further refinement of the catheter position was performed. Refinement >10 mm, or in case of catheter pointing directly at the aortic root or posterior wall were considered as major repositioning. Thirty-four patients required major repositioning. Regression analysis revealed age (P: 0.0001, Wald: 12.9, 95% confidence interval: 1.04-1.16), left atrial diameter (P: 0.01, Wald: 6.6, 95% confidence interval: 1.04-1.34), previous PVI (P: 0.01, Wald: 6.3, 95% confidence interval: 1.31-8.76), and atrial septal thickness (P: 0.03, Wald: 4.5, 95% confidence interval: 1.05-3.4) as independent predictors of major revision with TEE. CONCLUSION: Routine 2D TEE in addition to traditional fluoroscopic TP appears to be very useful to guide the TP assembly in a correct puncture position and thus, to avoid TP-related complications. However, further randomized prospective comparative studies are necessary to support these suggestions.

Cryomap failure.

BACKGROUND: The use of cryomapping at a temperature of -30 degrees to produce reversible lesions has been reported to improve the safety of accessory pathways ablation performed close to the normal conduction system while maintaining efficacy. MATERIALS AND METHODS: We reviewed all the ablation cases in which cryothermal technology was employed in our institution. Cryoablation and cryomapping temperature settings, number and time of the applications, recorded cardiac electrograms and ablation outcomes were analyzed. RESULTS: In three of nine cases where cryoablation was used for accessory pathway ablation, cryomapping failed to identify the location of the pathway or to prevent AV block. CONCLUSIONS: We postulate that currently recommended cryomapping settings are inadequate for all accessory pathways ablation.

One-puncture, double-transseptal catheterization manoeuvre in the catheter ablation of atrial fibrillation.

Pulmonary vein isolation (PVI) guided by circumferential mapping has been established as a curative treatment of atrial fibrillation. In the PVI technique, two transseptal catheters are necessary for mapping and catheter ablation. The one-puncture, double-transseptal catheterization manoeuvre is generally used in the PVI technique. However, to the best of our knowledge, there have been no reports describing transseptal manoeuvre in detail. In this article, the manoeuvre to achieve double-transseptal catheterization easily and safely is described.

Transseptal endocardial left ventricular pacing: an alternative technique for coronary sinus lead placement in cardiac resynchronization therapy.

BACKGROUND: Coronary sinus (CS) lead placement for transvenous left ventricular (LV) pacing in cardiac resynchronization therapy (CRT) has a failure rate at implant and short-term follow-up between 10% and 15%. OBJECTIVE: The purpose of this study was to assess the feasibility of transseptal endocardial LV pacing in patients in whom transvenous CS lead placement had failed. METHODS: An atrial transseptal LV lead placement was attempted in 10 patients (six females, age 69.4 +/- 9.6 years), in whom CS lead placement for CRT had failed. After transseptal puncture and septal dilatation from the femoral route, the left atrium was cannulated with a combination of catheters and guide wires from the left or right subclavian vein. After advancement of this guide catheter into the LV, a standard bipolar screw-in lead could be implanted in the posterolateral wall. All patients were maintained on anticoagulant therapy with warfarin after implant. RESULTS: An LV lead could be successfully implanted in nine of the 10 patients. The stimulation threshold was 0.78 +/- 0.24 V, and the R-wave amplitude was 14.2 +/- 9.7 mV. At 2 months' follow-up, the stimulation threshold was 1.48 +/- 0.35 V with a 0.064 +/- 0.027 ms pulse width. There was no phrenic nerve stimulation observed in any of the patients. There were no thromboembolic complications at follow-up. CONCLUSIONS: LV transseptal endocardial lead implantation from the pectoral area is a feasible approach in patients with a failed CS approach and in whom epicardial surgical lead placement is not an option. Longer follow-up is warranted to determine the risk of thromboembolic complications.

Idiopathic ventricular arrhythmias originating from the tricuspid annulus: Prevalence, electrocardiographic characteristics, and results of radiofrequency catheter ablation.

BACKGROUND: Idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) arising from the tricuspid annulus have been reported. OBJECTIVE: The purpose of this study was to clarify the prevalence and characteristics of VT/PVCs originating from the tricuspid annulus. METHODS: The ECG characteristics and results of radiofrequency (RF) catheter ablation were analyzed in 454 patients with idiopathic VT/PVCs. RESULTS: Thirty-eight (8%) patients had VT/PVCs arising from the tricuspid annulus: 28 VT/PVCs (74%) originated from the septal portion of the tricuspid annulus and the remaining 10 (26%) from the free wall of the tricuspid annulus. QRS duration and Q-wave amplitude in each of leads V1-V3 were greater in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (all P < .01). "Notching" of the QRS complex was observed more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .01). A Q wave in lead V1 was observed more often in VT/PVCs arising from the septum of the tricuspid annulus than those from the free wall of the tricuspid annulus (P < .005). R-wave transition occurred beyond lead V3 more often in VT/PVCs arising from the free wall of the tricuspid annulus than those from the septum of the tricuspid annulus (P < .005). RF catheter ablation eliminated 90% of the VT/PVCs arising from the free wall of the tricuspid annulus but only 57% of the VT/PVCs arising from septum of the tricuspid annulus. CONCLUSION: Idiopathic VT/PVCs arising from tricuspid annulus are not rare, and the detailed origin can be determined by ECG analysis. The preferential site of origin was the septum but also could be the free wall of the tricuspid annulus.

Right septal macroreentrant tachycardia late after mitral valve repair: Importance of surgical access approach.

BACKGROUND: Reentrant atrial tachycardias may occur after mitral valve surgery. These usually involve the left atrium or the lateral wall of the right atrium around the atriotomy scar. OBJECTIVE: The purpose of this study was to test whether ablation could eliminate atrial tachycardia after mitral valve repair. METHODS: Three patients (two men, one woman; mean age 57 +/- 12 years) were studied 48 +/- 38 months after mitral valve repair. In all cases, the surgical approach involved a transseptal incision. Tachycardia mapping was performed using multipolar catheters and the three-dimensional electroanatomic mapping system. The mean flutter cycle length was 313 +/- 21 ms. All patients had dual-loop reentry with one circuit around a septal scar and the other circuit around the tricuspid annulus. RESULTS: Successful radiofrequency ablation of the septal circuit was performed between the scar and the superior tricuspid annulus in all three cases. CONCLUSION: After mitral valve repair using a transseptal incision, dual-loop reentry may occur around the septal scar and the tricuspid annulus. Successful ablation may be achieved with an ablation line between the scar and the tricuspid annulus.

The superior transseptal surgical approach to mitral valve creates slow conduction.

BACKGROUND: Atrial tachycardia is very frequent after mitral valve surgery using the superior transseptal approach. METHODS: Sixteen patients operated on for mitral valve disease (superior transseptal approach = Group A, n = 9, and left atrial approach = Group B, n = 7) underwent radiofrequency catheter ablation of atrial tachycardia guided by electroanatomic mapping. Twenty-six consecutive patients without previous cardiac surgery with typical atrial flutter served as controls (Group C). RESULTS: Atrial tachycardia occurred earlier after the operation in Group A than in Group B (median 97 vs 2,159 days, P = 0.003). Typical atrial flutter was the most frequent circuit in all groups (Group A-7 patients, Group B-5 patients, Group C-26 patients). Three patients in Group A developed right atrial incisional tachycardia. Ten of 14 tachycardia circuits (typical atrial flutter, n = 7, incisional tachycardia, n = 3) in Group A depended on the corridor between the right atrial part of the atriotomy and the tricuspid annulus. Slow conduction during typical atrial flutter was detected in this corridor in Group A, but not in the corresponding region in Groups B and C (P < 0.001). The cycle length of typical atrial flutter was longer in Groups A and B than in Group C (mean 283 ms and 282 ms vs 233 ms, P = 0.003). Patients in Group B with typical atrial flutter had larger right atria than patients in Group A or Group C (mean 156 mL vs 96 mL and 113 mL, P = 0.033). CONCLUSIONS: The superior transseptal incision may predispose to atrial tachycardia by creating slow conduction between the atriotomy and the tricuspid annulus.

Catheter-based intracardiac echocardiography in the interventional cardiac laboratory.

Recent advances in technology have engendered a renewed enthusiasm in the use of intracardiac echocardiography (ICE) to guide and assess cardiac interventions. AcuNav is a phased-array sector imaging probe equipped with color and spectral Doppler capabilities. Previous-generation imaging catheters yielded unfamiliar limited-depth radial images with no flow information. Current imaging technology such as the AcuNav has not only consolidated the role of ICE but opened newer applications in the interventional laboratory. ICE has clear advantages over transesophageal echocardiography as the imaging modality of choice in the cardiac catheterization and electrophysiological laboratories. We review the technical evolution of ICE and describe the expanded utility of the AcuNav imaging catheter during cardiac interventions.

Entrainment mapping of dual-loop macroreentry in common atrial flutter: new insights into the atrial flutter circuit.

INTRODUCTION: The aim of this study was to determine using entrainment mapping whether the reentrant circuit of common type atrial flutter (AFL) is single loop or dual loop. METHODS AND RESULTS: In 12 consecutive patients with counterclockwise (CCW) AFL, entrainment mapping was performed with evaluation of atrial electrograms from the tricuspid annulus (TA) and the posterior right atrial (RA) area. We hypothesized that a dual-loop reentry could be surmised from "paradoxical delayed capture" of the proximal part of the circuit having a longer interval from the stimulus to the captured beat compared with the distal part of the circuit. In 6 of 12 patients with CCW AFL, during entrainment from the septal side of the posterior blocking line, the interval from the stimulus to the last captured beat was longer at the RA free wall than at the isthmus position. In these six patients with paradoxical delayed capture, flutter cycle length (FCL) was 227 +/- 12 ms and postpacing interval minus FCL was significantly shorter at the posterior blocking line than at the RA free wall (20 +/- 11 ms vs 48 +/- 33 ms, P < 0.05). In two of these patients, early breakthrough occurred at the lateral TA. A posterior block line was confirmed in all six patients in the sinus venosa area by intracardiac echocardiography. CONCLUSION: Half of the patients with common type AFL had a dual-loop macroreentrant circuit consisting of an anterior loop (circuit around the TA) and a posterior loop (circuit around the inferior vena cava and the posterior blocking line).

Cryoenergy catheter ablation: a new technique for treatment of permanent junctional reciprocating tachycardia in children.

INTRODUCTION: Permanent junctional reciprocating tachycardia (PJRT) is an infrequent form of reciprocating tachycardia, almost incessant from childhood and usually refractory to drug therapy. Radiofrequency catheter ablation currently is the first-line therapy for PJRT, but its application in the septal region may be associated with complications. In contrast, cryoenergy has several advantages, such as the ability to test the effects of ablation while the lesion is still forming, thus reducing the number of ineffective, useless, and potentially harmful lesions. The aim of this study was to investigate the potential clinical utility of percutaneous cryoenergy catheter ablation for treatment of pediatric patients with PJRT. METHODS AND RESULTS: Four patients (age 14 +/- 5 years; mean +/- SD) with a clinical diagnosis of PJRT underwent catheter cryoablation. The ablation was successfully accomplished in 4 (100%) of 4 patients. The mean +/- SD number of cryoapplications was 1.8 +/- 0.8, and from 1 to 6 cryomappings were performed for each permanent cryolesion. The successful site was in the mid-septal region (2 patients), at the coronary sinus orifice (1 patient), and in the middle cardiac vein (1 patient). No complications with cryoablation were reported, nor was there prolongation of the AH interval during cryomapping or cryoablation. No pain was reported by patients during the cryoenergy catheter ablation procedure. PJRT recurrence occurred in 1 patient who underwent a second successful cryoablation procedure. CONCLUSION: The outcomes of cryoenergy catheter ablation in these 4 patients treated for PJRT suggest that cryoablation is a safe, effective, and pain-free technique for treating pediatric patients with PJRT.

Catheter ablation of ventricular tachycardia by intramyocardial injection of ethanol in an animal model of chronic myocardial infarction.

INTRODUCTION: Direct injection of ethanol into myocardium has been shown to create large, well-demarcated lesions with transmural necrosis in normal ventricular myocardium and in regions of healed myocardial infarction. The aim of this study was to investigate the effects of direct ethanol injection on the inducibility of ventricular tachycardia (VT) in an animal model of chronic myocardial infarction. METHODS AND RESULTS: Eight sheep with reproducibly inducible VT underwent an electrophysiologic study 139 +/- 65 days after myocardial infarction. Noncontact mapping was used to analyze induced VT. Fifteen different VTs were targeted for catheter ablation. Ablation was achieved by catheter-based intramyocardial injection of a mixture of 96% ethanol, glycerine, and iopromide (ratio 3:1:1). Direct intramyocardial ethanol injection resulted in noninducibility of any VT 20 minutes after ablation in 7 of 8 animals. Four of 5 animals with initially successful ablation remained noninducible for any VT at follow-up study at least 2 days after the ablation procedure. Microscopic examination revealed homogeneous lesions with interstitial edema, intramural hemorrhage, and myofibrillar degeneration at the lesion border. The lesions were well demarcated from the surrounding tissue by a border zone of neutrophilic infiltration. CONCLUSION: Catheter ablation of VT by direct intramyocardial injection of ethanol during the chronic phase of myocardial infarction is feasible. It may be a useful tool for catheter ablation when the area of interest is located deep intramyocardially or subepicardially or when a more regional approach requires ablation of larger amounts of tissue.

"Transseptal" technique through atrial baffles for 3-dimensional mapping and ablation of atrial tachycardia in patients with d-transposition of the great arteries.

Access to targets for radiofrequency ablation in patients with congenital heart disease may be limited by anatomy and by surgically placed obstacles. In patients with atrial switch anatomy for d-transposition of the great arteries, the critical isthmus for maintenance of intraatrial macroreentry circuits is found often on the pulmonary venous side of the atrial baffle. A retrograde approach is extremely difficult for these arrhythmias. Use of transseptal techniques for diagnostic catheterization in these patients has been reported. We report the use of a transseptal technique in two cases in conjunction with 3-dimensional electroanatomic mapping for the successful ablation of atrial reentry tachycardias in patients with Mustard and Senning anatomy.

Radiofrequency catheter ablation of septal accessory pathways in the pediatric age group.

Radiofrequency catheter ablation (RCA) of septal accessory pathways may be technically challenging in children due to the risk of inadvertent atrioventricular (AV) block in the setting of small cardiac dimensions. Outcomes were reviewed for all patients aged < or =19 years with manifest and concealed septal accessory pathways undergoing RCA since 1990 at a single institution. One hundred forty-five procedures were performed in 127 patients (mean age 11.6 years). The number of studies according to accessory pathway location were: anteroseptal (n = 36), midseptal (n = 20), mouth of coronary sinus (n = 40), middle cardiac vein (n = 6), right posteroseptal (n = 21), and left posteroseptal (n = 22). Ablation was deferred for 9 patients (6 anteroseptal and 3 midseptal) in favor of additional pharmacologic trials. Acute success rates for targeted accessory pathways were: anteroseptal (96%), midseptal (94%), mouth of coronary sinus (88%), middle cardiac vein (100%), right posteroseptal (100%), and left posteroseptal (96%). Recurrence rates during follow-up were: anteroseptal (14%), midseptal (12%), mouth of coronary sinus (3%), right posteroseptal (4%), and left posteroseptal (4%). Permanent second or third degree AV block occurred in 4 of 136 RCA attempts (3%), involving 2 anteroseptal and 2 midseptal pathways. In 3 of these 4 cases, a high probability of block was anticipated from prior ablation efforts, prompting pacemaker insertion before or in conjunction with RCA. Thus, in the pediatric age group, acute RCA success rates for septal accessory pathways can exceed 90%. The risks of AV block and accessory pathway recurrence are most relevant to anteroseptal and midseptal pathways. These data may be factored into patient selection and the decision whether to ablate.