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The use of transthoracic echocardiography (TTE) is common during cardiopulmonary resuscitation (CPR) from cardiac arrest, but logistic and practical challenges of obtaining satisfactory images without sacrificing the quality of CPR have resulted in some centers utilizing transesophageal echocardiography (TEE) during CPR. Although TEE avoids many of the downsides of TTE, several challenges exist in routine deployment. An alternative approach, intracardiac echocardiography (ICE), is routinely used by electrophysiologists during regular cardiac electrophysiologic procedures, such as atrial ablation for the treatment of atrial fibrillation. In this review, we evaluate various considerations in the potential for use of ICE as a novel means of enhancing resuscitation during CPR.

Purpose Cryoablation is used in the treatment of atrial fibrillation and other cardiac arrhythmias. This study evaluated a novel 10-cm flexible nitrous oxide cryoprobe in an ovine model of atrial ablation. Description Six sheep were anesthetized, underwent a left thoracotomy, and were placed on cardiopulmonary bypass. A left atriotomy was performed, and the cryoprobe was applied endocardially for 120 seconds at less than –40°C to 4 sites on the left atrium. The atrium was closed and the animals were allowed to recover. After 30 days, the animals were euthanized. Transmurality was evaluated in 5-mm sections of each lesion using 2,3,5-triphenyltetrazolium chloride (TTC) and Masson's trichrome staining. Evaluation All animals survived. One hundred four of 106 sections (98%) were transmural by TTC; 103 of 106 (97%) sections were transmural by trichrome staining. There was no late atrial perforation, intraluminal thrombus, or thromboembolism. Conclusions The device reliably produced transmural lesions in a chronic ovine model. Its performance was equivalent to that of other nitrous oxide cryoablation systems.

The purpose of this study was to compare health care costs associated with repeat ablation of atrial fibrillation (AF) with health care costs associated with a successful first procedure.Catheter ablation has become established as a rhythm control strategy for symptomatic paroxysmal and persistent AF. The economic impact of ablation is not completely understood, and it may be affected by repeat procedures performed for recurrent AF.The source of data was the MarketScan (Truven Health, Ann Arbor, Michigan) administrative claims dataset from April 2008 to March 2013, including U.S. patients with private and Medicare supplemental insurance. Patients who underwent an outpatient atrial ablation procedure and a diagnosis of AF were identified. Total health care cost was calculated for 1 year before and after the ablation. Patients were categorized as having undergone a repeat ablation if an additional ablation was performed in the following year.Of 12,027 patients included in the study, repeat ablation was performed in 2,066 (17.2%) within 1 year. Patients with repeat ablation had higher rates of emergency department visits (43.4% vs. 32.2%; 0.001) and subsequent hospitalization (35.6% vs. 21.5%; p 0.001), after excluding hospitalizations for the repeat procedure. Total medical cost was higher for patients with repeat ablation ($52,821 vs. $13,412; p 0.001), and it remained 46% higher even after excluding the cost associated with additional ablations ($19,621 vs. $13,412; p 0.001).Health care costs are significantly higher for patients with a repeat ablation for AF than for patients with only a single ablation procedure, even though both groups have similar baseline characteristics. The increased costs persist even after excluding the cost of the repeat ablation itself. These results emphasize the economic benefit of procedural success in AF ablation.

Background Atrial fibrillation (AF) is the most common sustained arrhythmia. About 60% of patients with rheumatic heart disease have persistent AF. Methods A total of 197 patients underwent valve replacement concomitant bipolar radiofrequency ablation (BRFA). Patients were divided into the biatrial ablation group and the simplified right atrial ablation group. In biatrial ablation group, the patients underwent a complete left and right atrial ablation. In simplified right atrial ablation group, the patients underwent a complete left atrial ablation and a simplified right atrial ablation. Results The conversion of sinus rhythm (SR) was high in both groups during the follow-up period. In the simplified right atrial ablation group, SR conversion rate was 88.29% at discharge. At six months and 12 months after surgery, 87.39% of patients and 86.49% of patients were in SR free of antiarrhythmic drugs, respectively. While in the biatrial ablation group, SA conversion rate was 89.53% at discharge. Percentage of patients in SR free of antiarrhythmic drugs was 88.37% and 88.37% at six months and 12 months after surgery, respectively. Echocardiography showed left atrial diameter decreased significantly after the surgery in the two groups. The ejection fraction and fractional shortening were improved significantly, without significant differences between the two groups. Conclusions The results suggest that the concomitant left atrial and simplified right atrial BRFA for AF in patients undergoing valve replacement can achieve similar early efficiency as biatrial ablation.

Introduction Iatrogenic atrial tachyarrhythmias have increased with the widespread application of left atrial ablative procedures to treat atrial fibrillation. Methods and results Entrainment and activation mapping were utilized to study the mechanisms of atrial flutter in two patients who presented with atypical atrial flutter after high intensity focused ultrasound (HIFU) atrial ablation for persistent atrial fibrillation during the course of concomitant cardiac surgery. Case 1: Atrial flutter with CL of 340 ms was demonstrated to be mediated by entry into and exit from the partially isolated posterior left atrium (LA) with conduction delay across at least one of the connections. The exit site was near the left superior pulmonary vein (LSPV) and the entrance site was near the right inferior pulmonary vein (RIPV) as demonstrated by activation and entrainment mapping. Case 2: Entrainment mapping was highly suggestive of inferior exit from the HIFU ablation line between the two inferior pulmonary veins. Flutter terminated during trans-septal procedure and could not be re-induced. Activation mapping of the LA during pacing revealed the inferior exit and left superior entrance site, both of which were successfully ablated, isolating the posterior LA. Conclusions Re-entrant atrial flutter post-HIFU epicor Maze is caused by slow conduction at entry and exit sites from the otherwise isolated posterior LA wall. In both cases, gaps were found close to the LSPV and RIPV which may reflect difficulty in achieving proper contact between the HIFU device and the left atrial wall at these sites. These gaps are amenable to catheter ablation.

Background Radiofrequency (RF) ablation to treat atrial arrhythmia is limited by the inability to reliably assess lesion durability and transmurality. Objective The purpose of this study was to determine the feasibility of photoacoustic characterization of myocardial ablation lesions in vitro. In this study, we investigated the feasibility of combined ultrasound (US) and spectroscopic photoacoustic imaging to visualize RF ablation lesions in three dimensions (3D) based on unique differences in the optical absorption spectra between normal and ablated myocardial tissue. Methods Tissue samples were excised from the ventricles of fresh porcine hearts. Lesions were generated using an RF catheter ablation system using 20 to 30 W of power applied for 40 to 60 seconds. Ablated samples were imaged in the near-infrared regime (740–780 nm) using a combined PA/US imaging system. Measured PA spectra were correlated to the absorption spectra of deoxyhemoglobin and ablated tissue to produce a tissue characterization map (TCM) identifying 3D lesion location and extent. Tissue samples were stained and photographed for gross pathology. TCM and gross pathology images were coregistered to assess TCM accuracy. Results TCM reliably characterized ablated and non-ablated tissue up to depths of 3 mm. TCM also assessed lesion position and extent with submillimeter accuracy in multiple dimensions. Segmented TCMs achieved >69% agreement with gross pathology. Conclusion The study results suggest that spectroscopic photoacoustic imaging has the potential to accurately assess RF ablation lesion size and position with submillimeter precision and may be well suited to guide transcatheter RF atrial ablation in clinical practice.

Radiofrequency Catheter ablation (RFA) of atrial ablation (AF) is an important therapy for AF. Atrio-esophageal fistula (AEF) is a rare but lethal complication. Rapid diagnosis and treatment with surgical correction can potentially prevent death. Neurologic symptoms with or without fever occurring

Atrial-esophageal fistula (AEF) is an exceedingly rare but often fatal complication of catheter ablation for atrial fibrillation (AF). A 55-year-old male with AF underwent ablation 2 months prior presented for acute stroke. CT and MRI of the brain revealed multiple acute infarcts in bilateral

Recent randomized controlled study suggested improved outcomes after atrial ablation in patients with HFrEF. We utilized the 1999-2014 National Inpatient Sample(NIS) database to study early effects of AF ablation in patients with HFrEF and HFpEF. We identified patients with HFrEF or HFpEF, who were

Background Cardiac resynchronization therapy (CRT) and atrial ablation procedures currently lack a noninvasive imaging modality for reliable treatment planning and monitoring. Electromechanical wave imaging (EWI) is an ultrasound-based method that has previously been shown to be capable of noninvasively and transmurally mapping the activation sequence of the heart in animal studies by estimating and imaging the electromechanical wave, that is, the transient strains occurring in response to the electrical activation, at both high temporal and spatial resolutions. Objective To demonstrate the feasibility of transthoracic EWI for mapping the activation sequence during different cardiac rhythms in humans. Methods EWI was perfor`med in patients undergoing CRT and a left bundle branch block (LBBB) during sinus rhythm, left ventricular pacing, and right ventricular pacing, as well as in patients with atrial flutter (AFL) before intervention, EWI findings from patients with AFL were subsequently correlated with results from invasive intracardiac electrical mapping studies during intervention. In addition, the feasibility of single-heartbeat EWI at 2000 frames/s is demonstrated in humans for the first time in a patient with both AFL and right bundle branch block (RBBB). Results The electromechanical activation maps demonstrated the capability of EWI to localize the pacing sites and characterize the bundle branch block activation sequence transmurally in patients with CRT. In patients with AFL, the EWI propagation patterns obtained with EWI were in excellent agreement with those obtained from invasive intracardiac mapping studies. Conclusions Our findings demonstrate the potential capability of EWI to aid in the assessment and follow-up of patients undergoing CRT pacing therapy and atrial ablation, with preliminary validation in vivo.

Background Magnetic resonance imaging (MRI) allows visualization of location and extent of radiofrequency (RF) ablation lesion, myocardial scar formation, and real-time (RT) assessment of lesion formation. In this study, we report a novel 3-Tesla RT -RI based porcine RF ablation model and visualization of lesion formation in the atrium during RF energy delivery. Objective The purpose of this study was to develop a 3-Tesla RT MRI-based catheter ablation and lesion visualization system. Methods RF energy was delivered to six pigs under RT MRI guidance. A novel MRI-compatible mapping and ablation catheter was used. Under RT MRI, this catheter was safely guided and positioned within either the left or right atrium. Unipolar and bipolar electrograms were recorded. The catheter tip–tissue interface was visualized with a T1-weighted gradient echo sequence. RF energy was then delivered in a power-controlled fashion. Myocardial changes and lesion formation were visualized with a T2-weighted (T2W) half Fourier acquisition with single-shot turbo spin echo (HASTE) sequence during ablation. Results RT visualization of lesion formation was achieved in 30% of the ablations performed. In the other cases, either the lesion was formed outside the imaged region (25%) or the lesion was not created (45%) presumably due to poor tissue–catheter tip contact. The presence of lesions was confirmed by late gadolinium enhancement MRI and macroscopic tissue examination. Conclusion MRI-compatible catheters can be navigated and RF energy safely delivered under 3-Tesla RT MRI guidance. Recording electrograms during RT imaging also is feasible. RT visualization of lesion as it forms during RF energy delivery is possible and was demonstrated using T2W HASTE imaging.

Radiofrequency (RF) ablation of arrhythmias induces myocardial damage and release of biomarkers. This study aimed to assess the kinetics of heart-type fatty acid-binding protein (h-FABP), a cytosolic protein released after myocardial injury incurred by both atrial and ventricular RF ablation, compared to other markers of myocardial injury.h-FABP, cTnI, CK-MB(mass) and myoglobin were evaluated in 30 patients with atrial or ventricular tachyarrhythmias before, immediately after and at 3, 6 and 24h after the procedure.h-FABP increased immediately after the procedure in all subjects (6.6 ± 1.2 μg/L vs 2.7 ± 0.3, p0.001) but increased significantly only in ventricular ablations. The peak of h-FABP significantly correlates with the values of time for mean power of RF application in both the entire patient cohort and in ventricular ablations.h-FABP may be an early parameter for monitoring RF-induced lesions and the site of ablation was relevant for biomarker increase.

Background Pulmonary vein (PV) isolation has become a cornerstone for ablation of atrial fibrillation (AF). Circular mapping catheter (CMC)–guided techniques for detection of lesion gaps are challenging. Objective The present study describes a new concept of circumferential PV ablation aiming at bidirectional conduction block based on simultaneous pacing and ablation through the tip of a single mapping/ablation catheter. Methods A total of 147 patients with AF received circumferential PV ablation. In persistent AF, a posterior "box" lesion and a mitral isthmus line were added. All procedures were performed in sinus rhythm. Gaps within the left atrial (LA) ablation lines were detected and closed using voltage and pace mapping through the mapping/ablation catheter. Bidirectional conduction block was the procedural end point. Subsequently, the end point was validated by an independent electrophysiologist using a CMC. Results Procedural and radiation time measured 188 ± 55 and 37 ± 15 min. Bidirectional PV conduction block (lack of PV potentials and lack of LA capture) was found in 140 of 147 (95%) patients with single mapping/ablation catheter and in 138 of 147 (94%) patients with CMC. Early PV reconduction was seen in 22 of 147 (15%) patients. After 12 months follow-up, 84% of the patients were free from AF and/or atrial macro–re-entrant tachycardia. The rate of reablations was 10% and 24% for patients with paroxysmal and persistent AF, respectively. Conclusion Pacing and ablation from the tip of the mapping/ablation catheter is feasible to detect and close gaps within long atrial ablation lines to consistently achieve bidirectional conduction block.

The Cox-Maze procedure is an effective treatment for atrial fibrillation with a long-term freedom from recurrence of >90%. The original procedure was highly invasive and required cardiopulmonary bypass (CPB). Modifications of the procedure have been proposed so that the procedure can be done without CPB. These approaches proposed to use alternative energy sources, to replace cut and sew lesions with lines of ablation, made from the epicardium on the beating heart. This has been challenging because the atrial wall muscle thickness is extremely variable and can be covered with an epicardial layer of fat. Moreover, the circulating intracavitary blood acts as a potential heat sink, making transmural lesions difficult to obtain. In this report, we summarize the use of nine different unidirectional devices to create continuous transmural lines of ablation from the atrial epicardium in a porcine model. We define a unidirectional device as one in which all the energy is applied by a single transducer on a single heart surface. These include four radiofrequency, two microwave, two lasers, and one cryothermic device. The maximum penetration of any device was 8.3 mm. All devices except one, the Atricure IsolatorT pen, failed to penetrate 2.0 mm in some non-transmural sections. Future development of unidirectional energy sources should be directed at increasing the maximum depth and the consistency of penetration.

Objective The cut-and-sew Cox–Maze procedure is the gold standard for surgical treatment of atrial fibrillation, but it is associated with long-term impairment of left atrial mechanical function. We developed a bipolar, irrigated radiofrequency ablation device. We hypothesized that beating heart radiofrequency left atrial ablation would result in minimal acute changes in left atrial hemodynamics. Methods Six healthy subjects were studied. Combination pressure-conductance catheters were inserted into the left atrium and ventricle. With the use of the device, atrial ablation was performed on the beating heart without cardiopulmonary bypass, including electrical isolation of the posterior left atrium and atrial appendage myocardium. Simultaneous left-sided heart pressure–volume and intracardiac echocardiography data were acquired before ablation, after left atrial appendage ablation alone, and after all ablation (with and without appendage occlusion). The derived indices of left-sided heart mechanical function were examined. Results Relative to baseline, no significant diminishment in pressure–volume or intracardiac echocardiography-derived indices of global left-sided heart mechanical function were observed after ablation, with or without appendage occlusion. Mitral valve morphology and function were not significantly altered. A significant diminishment of atrial appendage systolic flow was noted after appendage ablation in association with spontaneous echocardiographic contrast in this region. Conclusions In this model, ablation does not seem to compromise global left-sided heart mechanical function. However, these findings mask regional diminishment in atrial appendage systolic function. This observation demonstrates that electrical isolation of the appendage should be accompanied by its occlusion or excision. Appendage occlusion after ablation does not seem to compromise left-sided heart mechanical function.

ObjectivesLate recurrence of atrial fibrillation frequently occurs after atrial ablation. Risk stratification for success and recurrence of the antiarrhythmic surgical procedure has not yet been established. We studied postoperative epicardial unipolar auriculograms to distinguish between high- and low-risk patients with late recurrence of atrial fibrillation.MethodsEpicardial atrial fibrillatory activity was registered in 70 patients with surgical ablation of permanent atrial fibrillation and postoperative recurrence through the temporary wires. The atrial activation pattern was characterized in 3 groups (type I, II, and III) using Wells’s criteria. The groups were homogeneous in the main clinical preoperative and surgical variables.ResultsMean atrial frequency of postoperative atrial fibrillation recurrence showed differences between groups: 225 ± 53 ms in type I, 177 ± 21 ms in type II, and 150 ± 19 ms in type III (P < .01). At the end of the study, sinus rhythm was achieved in 80% of the subjects with type I, 87.5% with type II, and 23.8% with type III (P < .001). During follow-up, late atrial fibrillation recurred in 21.7% of patients with type I, 17.4% with type II, and 64.2% with auriculogram type III. In multivariate regression analysis, the postoperative auriculogram type III was the only predictor of late atrial fibrillation recurrence (odds ratio 15.6; 95% confidence interval, 3.2–74.7; P < .001).ConclusionsThe unipolar epicardial auriculogram was able to characterize the complexity of the postoperative fibrillatory process and also to identify patients with a high risk of late recurrence. Auriculogram type III had a low success rate for the intraoperative ablation procedure. The lines of the ablation procedure facilitated organization of the auriculograms.

u e l e a d l d c e c u urgical treatment of atrial fibrillation during open heart surgery using alternative energy sources to crete lesions has become the standard of care at many nstitutions, including ours. This is particularly common n mitral valve patients because they have a very high reoperative incidence of atrial fibrillation and the necssary exposure required to perform an ablation is gained y accessing the left atrium for the valve surgery. Using nergy sources to create lesions in lieu of standard “cut nd sew” techniques may offer advantages in that they an be performed more rapidly and are not associated ith the same risk for bleeding. Laser energy is one of everal available energy sources that recently has been a

Rationale: Atrial fibrillation (AF) is the most common cardiac arrhythmia. A primary cause of AF is abnormal electrical activity stemming from ectopic foci located near muscle sleeves of the pulmonary veins. One of the most common and effective ways to treat AF is radiofrequency ablation (RFA) to electrically isolate the pulmonary veins from the left atrium or to directly eliminate ectopic foci. Because endocardial surface of left atrium is covered by thick interwoven layers of collagen and elastin, sites of RF ablation are hard to see.Hypothesis: We hypothesized that RFA-induced muscle damage in the left atrium can be visualized by implementing two different modalities of Hyperspectral Imaging (HSI) technology. HSI captures the entire spectrum for each pixel in an image. Post-acquisition analysis is used to reveal the main spectral components present in the sample to spatially separate regions in the image based on their spectra.Methods: Ablations were performed on a freshly excised porcine left atrial tissue. Images were acquired between 420-720 nm at a spatial resolution of 1392x1040 pixels, using a commercial HSI system (Nuance FX, PerkinElmer) fitted with a low magnification lens. UV LED (365nm) was used to illuminate samples for autofluorescence HSI datasets, while white light source was used for reflectance-based HSI experiments. Nonlinear unmixing was used to reveal the main spectral components and identify lesions sites.Results: Both HSI modalities greatly enhanced RF lesion visualization. The side by side comparison included: i) signal-to-noise ratio of the lesion component intensity profiles, ii) the optimum acquisition ranges and iii) the minimum number of wavelengths needed to differentiate between ablated and unablated tissue.Conclusion: The data provide technical basis for developing HSI catheter aiding real-time RFA lesion visualization during surgical ablation of AF.

Objective A technique for mimicking left atrial atriotomies using an ablation device that can be deployed without cardiopulmonary bypass has been developed. Methods In 12 healthy large (35-50 kg) adult pigs, maze-like ablation lesions were directly applied to the left atrial epicardium on the beating heart. The ablation device is irrigated, with a bipolar "hemostat" morphology, utilizing radiofrequency energy. Prior to and after ablation, left atrial electromechanical properties were measured during sinus rhythm in the latest 5 pigs using percutaneous endocardial catheter electromechanical mapping and intracardiac echocardiography. Pathologic analysis was performed acutely. Results All ablation lesions demonstrated conduction block along their entire course. Global left atrial conduction time (49.4 ± 8.8 milliseconds before vs 58.8 ± 9 milliseconds after) and pattern were not significantly altered. Although a significant amount (17.12% ± 9%) of myocardium was either ablated or electrically isolated, ablation was not associated with significant alterations in global left atrial mechanics (left atrium ejection fraction 19% before vs 17% after; pulmonary vein peak flow velocity 1.22 m/s before vs 1.38 m/s after; peak mitral inflow velocity 2.34 m/s before vs 2.64 m/s after), mitral valve function, nor left ventricular function. There was no evidence of atrial thrombus formation. Transmurality was achieved in most lesions with no evidence of charring or barotrauma. Conclusions Utilizing this ablation device, atrial lesions similar to the left component of the Maze procedure were deployed with uniform success in a beating heart without cardiopulmonary bypass or atriotomy and without adverse effects on left atrial electromechanics.

Background The optimal technique for producing linear radiofrequency thermal lesions in myocardial tissue is unclear. We compared epicardial ablation on the beating heart with endocardial ablation after cardioplegia. Methods Radiofrequency lesions were produced using a multielectrode malleable handheld probe in ovine myocardium with three wall thicknesses. Detailed analysis of lesion dimensions was used to assess the effects of site of ablation, muscle thickness, and duration of ablation. Results After epicardial atrial ablation, myocardial lesions were detected in all sections without macroscopically visible epicardial fat (n = 10), but only 43% (6/14) of sections with epicardial fat. Three of 24 atrial epicardial sections (13%) and 92% (23/25) of endocardial atrial lesion sections were clearly transmural. In thicker tissues lesion depth was independent of endocardial (right ventricle: 3.9 ± 1.1 mm, left ventricle: 3.8 ± 0.7 mm) or epicardial (right ventricle: 3.4 ± 0.6 mm, left ventricle: 4.3 ± 0.9 mm) ablation site. Epicardial lesions are less deep in thinner areas of myocardium ( p = 0.003). Lesions were all wider than they were deep. There was no significant increase in lesion depth with the increase in ablation duration from 1 to 2 minutes. Conclusions Lesions were unlikely to be transmural with either technique when the wall thickness was greater than about 4 mm. Epicardial fat has an important negative effect on epicardial lesion formation. Where epicardial fat is absent epicardially produced lesions penetrate less deeply when the wall thickness is small, possibly due to endocardial cooling by circulating blood. Prolongation of the duration of ablation from 1 to 2 minutes does not significantly increase lesion depth.

Background Recently, there has been renewed interest in simplifying a surgical cure for atrial fibrillation. Microwave energy ablation provides an easier and faster surgical technique, in lieu of traditional "cut and sew," which can also be applied on the beating heart. Methods Specific absorption rate (SAR) and thermal profiles were determined after microwave energy ablation intended for clinical application. Lesion geometry measures obtained in vitro with tissue equivalent media were compared with values collected from animal myocardium. Results Thermal profile analysis demonstrated lesion penetration depths of 2.5, 3, and 5 mm after 8, 16, and 24 seconds, respectively, with microwave power application of 40 W. Dosimetric studies performed using animal myocardium corresponded to the thermal profile analysis and showed that lesion depth was controlled by the output power and the ablation time. Conclusions Lesion geometry in tissue using microwave energy is similar to that predicted from in vitro analysis. The ablation depths and thermal profile of microwave ablation is favorable for performing atrial ablation, and this is corroborated by favorable early clinical results.

Background: Recently, there has been renewed interest in the development of minimally invasive procedures to treat atrial fibrillation. Unipolar radiofrequency catheters are plagued by poor results, in part because of their inability to produce transmural lesions. This study tested the ability of bipolar radiofrequency energy to create chronic transmural lesions on the beating heart that isolated atrial myocardium. Methods: Five sheep underwent a right thoracotomy. Baseline pacing was performed from the following targeted areas: right atrial appendage, superior vena cava, inferior vena cava, and right pulmonary veins. A cuff of atrial myocardium around the targeted tissue was clamped between the 2 arms of the device. Radiofrequency energy was delivered at 750 mA and continued until the tissue conductance between the electrodes reached a stable minimum level. After ablation, pacing was used to document tissue isolation. The animals survived for 30 days. Results: Twenty circumferential lesions were produced at the initial operation. The mean ablation time was 9.3 ± 4.0 seconds, and the mean peak temperature was 48.4°C ± 6.4°C. All lesions acutely and chronically isolated the targeted tissue. Trichrome staining showed that all lesions were transmural. There were no instances of pulmonary vein stenosis or thrombosis. Conclusions: Bipolar radiofrequency energy can produce permanent transmural linear lesions on the beating heart. Online measurement of tissue conductance reliably predicted lesion transmurality. This new technology may enable surgeons to perform a curative minimally invasive operation for atrial fibrillation on the beating heart. J Thorac Cardiovasc Surg 2002;124:708-13

Background . The purpose of this study was to develop a method of atrial ablation. In the IRK-151 infrared coagulator, light from a tungsten-halogen lamp is focused into a quartz rod. The distal exit plane is connected to a tip made of sapphire to allow linear ablation. Methods . Thirty-six lesions were created in 9 mongrel dogs. The beating ventricular myocardium was ablated from the epicardium. In each dog, 4 lesions were created by using the following durations of application: 3, 9, 15, and 21 seconds. After the ablation, the myocardium was fixed and stained. A linear lesion on the beating right atrial free wall was created. Before and after the ablation, epicardial plaque–electrode mapping was performed. Three months after ablation, remapping was performed. Results . The ablated myocardium had well-demarcated necrosis without carbonization or vaporization. The maximum depth was 10.3 ± 0.8 mm. The conducting pathway was blocked. The block, once made, continued for 3 months. Conclusions . The IRK-151 produces well-demarcated lesions that were deep enough for atrial ablation to block the conducting pathway.

Ablation for atrial fibrillation (AF) ranks as one of the greatest successes and a perplexing failure of contemporary cardiac electrophysiology. Despite tremendous continued enthusiasm, several experienced interventional electrophysiologists consider AF ablation as a palliative rather than a curative procedure. This likely reality has resulted from the increasingly documented high rates of recurrence of AF following ablation. The cornerstone for AF ablation is pulmonary vein (PV) isolation, which involves some form of circumferential atrial ablation. The lack of uniform long-term success has prompted 2 important questions: (1) Do we need to isolate the PVs or are other targets more appropriate? (2) Can we effectively and permanently isolate the PVs? It is essential to answer the latter question before we can address the former. In this issue of HeartRhythm, McClellan et al enlighten us on the potential relationship of specific PV anatomy and AF ablation outcomes. One hundred two patients underwent PV anatomy assessment with cardiac magnetic resonance or computed tomography. The authors report the correlation between anatomic variance, such as common left-sided PVs and the characteristic of the left atrial endocardial ridge, and recurrences following ablation. In most other cardiac arrhythmias, although topology (infarction, surgical scar, etc.) correlates with arrhythmogenesis in outcomes, the fact that anatomy impacts outcomes is not entirely intuitive. Possible questions that arise include whether varying pulmonary anatomy is a cause for AF or whether it simply represents a more difficult landscape for successful ablation. More generally, a fundamental question emerges: Is there anatomic and spatial fixity or altered atrial electrophysiology?

Atrial fibrillation is the most common arrhythmia in the United States. Procedural treatment options such as the MAZE procedure and radiofrequency ablation are available with reasonable success rates. However, there are risks inherent to these procedures, with atrioesophageal fistula being a rare but devastating complication. We report a patient with atrioesophageal fistula who presented with neurologic symptoms 20 days after her initial MAZE procedure, followed by a quick decline within 24 hours of presentation.

In 1987 Dr James Cox introduced a new operation for treating atrial fibrillation. The Maze procedure created several incisions throughout both the left and right atria. These incisions were designed to block the multiple macroreentrant circuits felt to be responsible for atrial fibrillation. Over the years Dr Cox and his group had developed a successful paradigm for introducing operations for cardiac arrhythmias. This paradigm was based on first developing a sound understanding of the fundamental substrates and interactive mechanisms. Successful surgical interventions were only introduced clinically after a thorough understanding of the basic electrophysiology and anatomy was developed in the laboratory in animal models [1]. After the clinical introduction of the Maze procedure it went through several iterations before settling on what has become the gold standard for treating atrial fibrillation, the Cox-Maze III procedure. Our long-term results at Washington University have revealed a cure rate of more than 96% at 10 years [2]. Despite its remarkable success the operation has not been widely adopted by surgeons, in part owing to its technical difficulty and complexity. There also is still significant morbidity associated with this operation including the need for pacemaker implantation in as many as 10% of patients. These problems have led numerous investigators around the world to develop potentially less invasive or simpler approaches to treating this extremely common arrhythmia. A common strategy has been to replace the surgical incisions with linear lines of ablation. Various energy sources have been used to perform this ablation including radiofrequency energy, microwave, laser, cryoablation, and ultrasound [3]. The objective of these new technologies is to replace the surgical incisions with lines of transmural ablation to create conduction block. Doing so would fulfill the goal of the Cox-Maze procedure to block reentrant circuits. Theoretically this would be less invasive and easier to perform as it would replace the traditional cut-and-sew technique. However because these new ablation devices are replacing a well-developed and extensively studied operation, it is imperative that they be safe and effective and at the same time provide a truly less invasive alternative treatment option. In the last several years many of these new technologies have been introduced clinically. The Food and Drug Administration has approved most of these devices only for soft-tissue coagulation. Unfortunately they have been used widely in an off-label manner for treating atrial fibrillation without adequate experimental or clinical investigation of their efficacy for arrhythmia ablation. The absence of peer-reviewed evaluation has led to many predictable problems. Because of the lack of established dose-response curves, surgeons have had to estimate appropriate ablation times to account for the varying thicknesses of pathologic atria encountered in the operating room. Moreover most of these technologies give no indication of when the lesion becomes transmural. These shortcomings have led to prolonged ablation times to ensure lesion transmurality. Not only can this lead to unintended collateral tissue injury [4] but also the lack of any verification of lesion transmurality and clinically relevant dose-response curves may explain the higher failure rate compared with the Cox-Maze III procedure that has been seen in some series [5, 6].

Background: Catheter ablation for atrial fibrillation (AF) is more efficacious than antiarrhythmic therapy. Post ablation recurrences reduce ablation effectiveness and are contributed by lesion discontinuity in the fibrotic linear ablation lesions. The anti-fibrotic role of statins in reducing AF is being assessed in current trials. By reducing the chronic pathological fibrosis that occurs in AF they may reduce AF. However if statins also have an effect on the acute therapeutic fibrosis of an ablation, this could exacerbate lesion discontinuity and AF recurrence. We tested the hypothesis that statins attenuate ablation lesion continuity in a recognised pig atrial linear ablation model. Aims: To assess whether Atorvastatin diminishes the bi-directional conduction block produced by a linear atrial ablation lesion. Methods: Sixteen pigs were randomised to statin (n=8) or placebo (n=8) with drug pre-treatment for 3 days and a further 4 weeks. At initial electrophysiological study (EPS1) 3D right atrium (RA) mapping and a vertical ablation linear lesion in the posterior RA with bidirectional conduction block were completed (Gepstein Circ 1999). Follow-up electrophysiological assessment (EPS2) at 28 days assessed bidirectional conduction block maintenance. Results: Data of 15/16 (statin=7) pigs were analysed. Mean lesion length was 3.7 ± 0.8cm with a mean of 17.9 ± 5.7 lesion applications. Bi-directional conduction block was confirmed in 15/15 pigs (100%) at EPS1 and EPS2. Conclusions: Atorvastatin did not affect ablation lesion continuity in this pig atrial linear ablation model. If patients are on long-term statins for AF reduction, periablation cessation is probably not necessary.