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Paralleling the growth in ablation of complex arrhythmias such as atrial fibrillation and ventricular tachycardia, advanced imaging technologies are becoming more commonplace in the care of the electrophysiology patients. Although intracardiac ultrasound remains the most commonly used imaging technique, advances in real-time MRI may change this in the future. We discuss the current use of intracardiac ultrasound, CT, including rotational angiography, MRI, with an emphasis on delayed-enhancement MRI, and positron emission tomography-CT in advanced ablation procedures. Image integration is emphasized and new technologies such as direct endoscopic visualization are discussed.

Background: The endocardial substrate for ventricular arrhythmias in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is thought to be caused by a progressive degenerative process. Many clinical decisions and treatment plans are guided by this pathophysiologic assumption, but the extent of progression of macroscopic endocardial scar and right ventricular (RV) dilatation have not been assessed., Methods and Results: Eleven patients with ARVD/C and ventricular tachycardia had 2 detailed sinus rhythm electroanatomic endocardial voltage maps (average, 291+/-122 points per map; range, 114 to 558 points) performed a mean of 57 months apart (minimum, 9 months) as part of ventricular tachycardia ablation procedures. Voltage-defined scar (<1.5 mV) and RV volume were measured by area and volume measurement software and compared. Two of the 11 patients had a clear increase in scar area (47 cm(2); 32 cm(2)) confirmed by visual inspection. The remaining 9 (81%; 95% CI, 48% to 98%) patients had no increase (<10-cm(2) difference) in scar area between studies. In contrast, 10 of the 11 patients had a significant increase in RV volume, with an average increase of 24% (212+/-67 mL to 263+/-52 mL; P< or =0.01)., Conclusions: In patients with ARVD/C and ventricular tachycardia, progressive RV dilatation is the rule, and rapid progression of significant macroscopic endocardial scar occurs in only a subset of patients. These results have important management implications, suggesting that efforts to prevent RV dilatation in this population are needed and that an aggressive substrate-based ablation strategy offers the potential to provide long-term ventricular tachycardia control.

Background: Pulmonary vein isolation (PVI) is increasingly used for treatment of atrial fibrillation (AF), but few reports exist regarding long-term success. We determined 5-year outcomes of PVI among patients with freedom from AF off antiarrhythmic drugs (AAD) for 1 year after PVI., Methods and Results: Consecutive patients with paroxysmal or persistent AF who underwent PVI at the University of Pennsylvania from 2000 to 2003 and were free from AF 1 year after ablation were included. Proximal isolation of PVs and non-PV triggers of AF was performed. Long-term ablation success, defined as freedom from AF off AAD after a single ablation procedure, was determined. All patients had transtelephonic monitoring at 3 to 6 months and 12 months and at least yearly contact thereafter. One hundred twenty-three patients were free of AF without AAD at 1 year. AF freedom off AAD was 85% at 3 years and 71% at 5 years, with an approximate 7% per year late recurrence rate after the first year. Patients with recurrent AF >or=5 years after index PVI were older, had larger left atrial size, more AF triggers and more likely had persistent AF. In multivariate analysis, persistent AF (odds ratio, 2.8; 95% confidence interval, 1.4 to 5.7, P=0.005) and age (odds ratio, 1.1; 95% confidence interval, 1.0 to 1.1, P=0.036) independently predicted long-term AF recurrence., Conclusions: Among patients with paroxysmal or persistent AF and AF freedom 1 year after segmental PVI, the majority (71%) remained free of AF for up to 5 years, with an approximate late recurrence rate of 7% per year. Continued vigilance for recurrent AF after PV isolation is warranted, particularly in patients with persistent AF.

The past decade has seen a remarkable period of discovery and refinement of ventricular tachycardia (VT) ablation in patients with left ventricular cardiomyopathy (LVCM). Patients with LVCM presenting with VT have a common substrate distribution involving predominantly the basal or perivalvular LV, which is often more dramatic on the LV epicardium. They typically present with multiple and often unstable tachycardias due to scar-based reentry. Percutaneous intrapericardial access can be safely performed in the electrophysiology laboratory and has greatly enhanced the efficacy of VT ablation in this setting by allowing detailed mapping. Epicardial ablation incurs unique procedural considerations that must be understood to safely and effectively perform the procedure., (Copyright © 2010. Published by Elsevier Inc.)

Purpose: Transesophageal echocardiography (TEE) is the gold standard in the evaluation for left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF) and is often performed prior to AF ablation. We routinely use intracardiac echocardiography (ICE) to assist in AF ablation; however, standard right atrial views do not provide adequate visualization of the LAA. As the incidence of thrombus in this population is relatively low, TEE incurs additional risk, cost, and patient discomfort. Novel views of the LAA with ICE may obviate the need for TEE in this population. We tested the hypothesis that due to their proximity, imaging the LAA from the pulmonary artery (PA) would provide equivalent sensitivity and specificity to TEE in detecting LAA thrombus in a swine model., Methods: Five domestic swine were utilized. Baseline images of the LAA with TEE were obtained. An 8Fr ICE catheter was placed in the left main PA, and imaging of the LAA was repeated. After transseptal puncture, an admixture of 2 cm(3) blood and 1,000 IU of thrombin was injected into the LAA, and imaging of the LAA was repeated. Two blinded, independent reviewers experienced in ICE assessed the images and adjudicated both the presence of thrombus and the subjective image quality., Results: The presence or absence of thrombus was correctly identified in all cases by both reviewers. Both reviewers rated the subjective quality of ICE images superior to TEE., Conclusions: ICE is equivalent to TEE in imaging LAA thrombus in a porcine model. Whether ICE can provide similar diagnostic accuracy and safety for detecting LAA thrombus in humans remains unproven.

Despite a decline in overall cardiovascular mortality, the incidence of sudden cardiac death (SCD) continues to rise. Patients who survive a myocardial infarction (MI) with depressed ejection fraction are at particularly high risk for SCD. The development of implantable cardioverter-defibrillators (ICDs) has revolutionized SCD prevention; however, despite the current fervor for device implantation, many unresolved questions remain about risk stratification in post-MI patients. This review presents the current indications and timing of ICD implantation for primary and secondary prevention of SCD after MI. Several conventional and investigational methods of risk stratification after MI, as well as current controversies regarding device implantation in specific patient populations, are also reviewed.

Radiofrequency catheter ablation of pulmonary veins has emerged as an effective therapy for patients with symptomatic atrial fibrillation. Advances in real-time intracardiac echocardiography with 2D and Doppler color flow imaging have led to it integration in atrial fibrillation ablation procedures. It allows imaging of the left atrium and pulmonary veins, including identification of anatomic variations. It has an important role in guiding transseptal catheterization, imaging the pulmonary vein ostia, assisting in accurate placement of mapping and ablation catheters, monitoring lesion morphology and flow changes in the ablated pulmonary veins, hence allowing titration of energy delivery. Importantly, it allows instant detection of procedural complications.

Background: Targeting of complex fractionated electrograms (CFEs) has been used as an adjunctive strategy to pulmonary vein isolation (PVI) in patients with persistent atrial fibrillation (AF). However, it is unclear whether CFEs should be targeted before or after PVI., Objectives: The purpose of this study was to examine the effect of PVI on CFE distribution in humans., Methods: We compared left atrial (LA) CFE maps acquired using the NavX system before and after PVI in patients with persistent AF. CFE maps were constructed from bipolar electrograms acquired from a circular mapping catheter. At each point, the mean AF cycle length (CL) was calculated automatically by averaging the intervals between deflections over a 4-second window. Sites with mean CL < or =120 ms were considered CFE+., Results: A total of 22 consecutive patients (82% male, age 58 +/- 9 years) were studied. At baseline, 47% of the LA was encompassed by electrograms with CL <120 ms. PVI had a significant effect on CFE characteristics, with an increase in mean LA AF CL (144 ms pre-PVI vs. 214 ms post-PVI; P <.01) and a decrease in CFE+ LA surface area (47% vs 23%; P <.01). There was significant reduction in CFE burden after PVI in both PV (50% vs. 6%; P <.01) and non-PV (61% vs. 39%; P <.01) regions., Conclusions: In patients with persistent AF, PVI results in a significant decrease in both PV and non-PV areas of CFE. To limit extensive LA ablation, PVI should be performed before targeting CFE when a combined approach is pursued.

Objectives: This study sought to identify the origin within the pulmonary vein (PV) of reproducible atrial fibrillation (AF) triggers., Background: Triggers for AF frequently originate from PVs. However, a systematic evaluation of the location of origin within the PV orifice and associated techniques for eliciting triggers has not been performed., Methods: Spontaneous triggers and those provoked with isoproterenol (up to 20 microg/min) and/or cardioversion in 45 patients with AF were identified using multipolar catheter recordings. In identifying origin, PVs were divided into 17 equal segments from ipsilateral PVs with "carina zone" (CZ) (7 segments between the PVs) and 10 "noncarina zone" (NCZ) segments., Results: Sixty-three reproducible triggers were noted in 37 of the 45 (82%) patients with 57 from PV and 6 (10%) from non-PV sites. Although triggers were identified from 26 of 34 distinct PV segments, most PV triggers (36, 63%) originated from CZ segments (p < 0.05) from both right (17 triggers) and left (19 triggers) PVs. The CZ triggers were more often spontaneous (11 of 36 in CZ vs. 2 of 21 in NCZ; p < 0.05) or elicited with CV (17 of 36 in CZ vs. 6 of 21 in NCZ; p < 0.05). In contrast, NCZ triggers were more likely to require isoproterenol to be provoked (13 of 21 [62%] vs. 8 of 36 [22%], p < 0.05)., Conclusions: Reproducible spontaneous and provoked PV triggers initiating AF can be observed in most patients undergoing AF ablation. These triggers most commonly originate from the carina region of both right and left PVs. Noncarina PV triggers more commonly require provocation with isoproterenol infusion.

Background: Targeting of complex fractionated electrograms (CFEs) has been described as an approach for catheter ablation of atrial fibrillation (AF); however, the distribution and temporal stability of CFE regions remain poorly defined., Methods: In patients with persistent AF referred for ablation, we performed two consecutive left atrial (LA) CFE maps prior to AF ablation. Bipolar electrograms were acquired during AF, and the mean AF cycle length and electrogram voltage were automatically determined at each point. Sites with mean CL

A repetitive, tunable, high-power vacuum ultraviolet laser operating on the 172-nm bound-free transition in xenon has been developed for use in photochemistry, selective excitation spectroscopy, and in the generation of coherent radiation in the XUV spectral region. A compact high-voltage generator is employed in conjunction with a coaxial cold-cathode diode to pump high-pressure xenon at a repetition rate of up to 10 Hz, though at present gas heating limits the operation of the laser to 0.5 Hz. The apparatus has been designed for compatibility with fluorine, and is consequently a suitable pumping source for the rare gas halide exciplex lasers. The gas handling techniques which enabled reliable, reproducible laser action to be achieved in xenon for several hundred pulses are described.