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Background: Nonsurgical subxiphoid pericardial access may be useful in ventricular tachycardia ablation and other electrophysiologic procedures but has a risk of right ventricular puncture., Objective: The purpose of this study was to identify a signature pressure frequency that would help identify the pericardial space and guide access., Methods: The study consisted of 20 patients (8 women and 12 men; mean age 59.1 +/- 14.2 years; left ventricular ejection fraction 25.2% +/- 12.2%; failed 1.8 +/- 0.5 endocardial ablations; unresponsive to 2.0 +/- 1.0 antiarrhythmic drugs; 6 ischemic cardiomyopathy, 12 nonischemic cardiomyopathy, 2 normal heart; 4 previous sternotomy) undergoing epicardial ventricular tachycardia ablation. After pericardial access was obtained, a 10Fr long sheath was used to record pressure inside the pericardium and pleural space. Pressures were analyzed using a fast Fourier transform to identify dominant frequencies in each chamber., Results: Mean pressures in the pleural space and the pericardium were not different (7.7 +/- 1.9 mmHg vs 7.8 +/- 0.9 mmHg, respectively). However, the pericardial space in each patient demonstrated two frequency peaks that correlated with heart rate (1.16 +/- 0.21 Hz) and respiratory rate (0.20 +/- 0.01 Hz), whereas the pleural space in each patient had a single peak correlating with respiratory rate (0.20 +/- 0.01 Hz)., Conclusion: The pericardial space demonstrates a signature pressure frequency that is significantly different from the surrounding space. This difference may make minimally invasive subxiphoid pericardial access safer for nonsurgeons and may have important implications for electrophysiologic procedures., (Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Unlabelled: Ventricular tachycardia (VT) is common among patients with Chagas' heart disease but the ultimate mechanisms responsible for its sustained and nonsustained forms are not understood. This study aimed at determining which factors differentiate between patients with sustained (S-VT) and nonsustained VT (NS-VT). Fifty-six consecutive chagasic patients with VT were prospectively selected: 28 patients with spontaneous S-VT and 28 patients with NS-VT. The patients underwent clinical, angiographic, electrophysiologic and myocardial perfusion examination. Syncope episodes (S-VT: 43% versus NS-VT: 11%, p = 0.007) and induction of S-VT by programmed ventricular stimulation (S-VT: 89% versus NS-VT: 7%, p = 0.001) were significantly more frequent in S-VT patients. Evidence of a scar-related reentry was observed in all 24 S-VT patients who underwent endocardial mapping for attempted radiofrequency ablation of 33 VTs. Overall, 29 VTs arose from the LV (88%) and 4 VTs arose from the RV (12%). Among these, 27 VTs (82%) were related to LV inferolateral scar, 2 VTs (6%) were related to LV apical scar, and 4 VTs (12%) were related to RV scars. A significantly higher prevalence of wall motion abnormalities (S-VT: 82% versus NS-VT: 46%, p = 0.005) and myocardial perfusion defects (basal segments, S-VT: 95.5% versus NS-VT: 44%, p = 0.001) was documented within the LV inferior and/or posterolateral regions in S-VT patients compared to NS-VT., In Conclusion: (a) VT may arise from various regions in both ventricles, but LV inferolateral scar is the main source of S-VT reentrant circuits; (b) there is good topographic correlation between myocardial perfusion, wall motion abnormalities and areas that originate S-VT; (c) although to a lesser extent, wall motion and perfusion defects also occur in a relevant proportion of chagasics with NS-VT.

Introduction: The subxyphoid pericardial mapping approach can be used to facilitate catheter ablation of postmyocardial-infarction ventricular tachycardia (post-MI VT), but the presence of dense adhesions is thought to preclude this approach in patients who have previously undergone open-chest cardiac surgery., Aims of the Study: This study reports the first use of a nonsurgical transthoracic epicardial approach in patients with scar-related VT and previous cardiac surgery., Methods: Five patients with a mean age of 67 +/- 10 years, left ventricular ejection fraction (LVEF) of 40 +/- 4.3%) and recurrent VT occurring 7 months to 10 years after cardiac surgery underwent combined endocardial and epicardial mapping and ablation during the same session. Because pericardial adhesions were anticipated to be denser in the anterior wall, the nonsurgical transthoracic epicardial puncture was directed to the inferior wall of the left ventricle. Failure to interrupt VT with radio frequency (RF) energy pulses delivered at the best endocardial or epicardial site prompted changing from one approach to the other., Results: During the epicardial puncture procedure, the contrast medium accumulated in the inferior wall instead of spreading around the cardiac silhouette. The pericardial sac could be entered in all patients, and mapping of the inferolateral epicardial wall of the left ventricle was feasible. Fourteen VTs were induced, of which 8 could not be mapped because of poor hemodynamic tolerance. Three of the remaining 6 mappable VTs were eliminated by endocardial ablation, 2 required an epicardial RF pulse to be rendered noninducible, and 1 VT was not eliminated. No intra- or postprocedural complications were noted despite full heparinization., Conclusion: Nonsurgical transthoracic epicardial catheter mapping and ablation of epicardial VT related to the inferolateral left ventricular wall are feasible in patients who have previously undergone open- cardiac surgery.

This study evaluates the effects of epicardial RF ablation on the coronary vessels in a canine model. Nonsurgical epicardial catheter ablation is a minimally invasive procedure that has proven to be efficacious for the treatment of VT. This approach is limited by concern regarding the potential adverse effects of RF ablation on the epicardial coronary arteries. After lateral thoracotomy, a multipolar linear ablation catheter was sewn adjacent to or crossing the LAD in nine mongrel dogs. Five of these dogs also had a standard 4-mm tip ablation catheter sewn adjacent to the LAD. RF pulses were delivered using temperature control. Animals were sacrificed 14 days after ablation for histological analyses. Using the 4-mm tip catheter, 22 consecutive single lesions of 2.67 +/- 0.35 mm depth were studied. The only coronary arterial change seen was replacement of the media with extracellular matrix. Using the linear ablation catheter, 117 pulses were applied to generate 24 linear lesions (3.8 +/- 1 mm depth). Replacement of the coronary arterial media with extracellular matrix proliferation was commonly seen, and severe hyperplasia occurred in one artery. Intravascular thrombosis occurred in six arteries. The internal perimeter of the vessel (0.78 +/- 0.49 mm vs 1.79 +/- 0.83 mm) was the only variable associated with severe arterial damage. The effects of RF ablation delivered adjacent to the LAD were limited to the media but when delivered above the artery, severe intimal hyperplasia and intravascular thrombosis may occur. Susceptibility to damage is inversely proportional to the vessel size.

Chronic Chagas' myocarditis can alter the myocardial substrate in a way that facilitates the emergence of fatal VT in a way similar to the long-term consequences of myocardial infarction. Post-myocardial infarction and Chagas' VT share many similarities: they are both macroreentrant circuits, entrainable, involving any wall segment from the endocardium to the epicardium. However, as compared to patients with post-MI VT, Chagasic patients tend to be younger and have a higher left ventricular ejection fraction. It is assumed, therefore, that their prognosis is closely related to VT treatment rather than the progression of the myocardial damage caused by the disease itself. Although sudden death is a rare event in patients in NYHA functional class I and II treated with amiodarone, VT recurrence rate is 30% a year. Drug therapy is ineffective for patients with advanced heart failure (100% recurrence rate/40% mortality in 1 year). Open-chest surgery is effective but requires very specialized centers and great expertise making its widespread use unrealistic. The results of combining RF endo/epicardial catheter ablation are still disappointing. Thus, research protocols on the search for new ablation technologies may greatly impact overall mortality in this subset of patients. This review will focus on the limitations of the current catheter-based ablation technology and suggest that an alternative approach is urgently needed. Experimental evidence of the efficacy of near infrared Lasers for catheter ablation will be reported along with investigations of the optical properties of the chagasic myocardium in the near infrared region to indicate that it might be not only feasible but also an appropriate choice to treat these patients.

RF ablation of idiopathic left ventricular outflow tract ventricular tachycardia (LOT-VT) may imply in significant risk of damaging the proximal left main if RF pulses are being delivered from the left sinus of Valsalva or from inside an epicardial coronary vein. This report describes a new approach to control LOT-VT by means of RF catheter ablation.

This case report describes the electrophysiological findings of a 62-year-old patient with chronic Chagas' disease and two distinct morphologies of sustained ventricular tachycardia that involved a mitral isthmus. Multiple RF applications were necessary to obtain a bidirectional conduction block in the mitral isthmus that was related to the interruption of both tachycardias. After the procedure, the patient presented massive cerebral infarction that progressed to coma and death. Autopsy showed acute and old lesions at the mitral isthmus and recent mitral annulus thrombosis.

Nonsurgical epicardial transthoracic catheter ablation is a minimally invasive procedure that has proven to be efficacious for the treatment of ventricular tachycardia (VT). The usefulness of this technique depends on the prevalence of epicardial circuits, which seem more frequent in Chagasic than post-myocardial infarction VT. This approach is limited by concern regarding the potential adverse effects of radiofrequency (RF) ablation on the coronary arteries. However, the effects of RF ablation delivered in the vicinity of a major coronary artery are limited to the medial artery. Severe intimal hyperplasia and intravascular thrombosis may occur only when RF ablation is delivered above the artery. Moreover, susceptibility to damage is inversely proportional to the vessel size. Coronary artery injury is an uncommon (< 1%) complication that could be prevented by a coronary angiogram prior to ablation. Hemopericardium, another predictable complication occurring in 10% of patients, can be easily controlled in the electrophysiology laboratory.

Objectives: We sought to evaluate feasibility, safety and results of transthoracic epicardial catheter ablation in patients with ventricular tachycardia occurring late after an inferior wall myocardial infarction., Background: Transthoracic epicardial catheter ablation effectively controls recurrent ventricular tachycardia (VT) in patients with Chagas' disease in whom epicardial circuits predominate. Epicardial circuits also occur in postinfarction VT., Methods: Fourteen consecutive patients aged 53.6 +/- 14.5 years with postinfarction VT related to the inferior wall were studied. The VT cycle length was 412 +/- 51 ms. Two patients had previously undergone unsuccessful standard endocardial radiofrequency energy (RF) ablation. The VT was incessant in one patient. Left ventricular angiography showed inferior akinesia in 13 patients and an inferior aneurysm in 1 patient. Ablation was performed with a regular steerable catheter placed into the pericardial sac by pericardial puncture., Results: The pericardial space was reached in all patients. Electrophysiologic evidence of an epicardial circuit was present in 7 of 30 VTs. Due to a high stimulation threshold, empirical thermal mapping was the only criterion used to select the site for ablation. Three VTs were interrupted during the first RF pulse. Two pulses were necessary to render it noninducible in 3 patients (1 VT per patient). In the remaining 4 VTs, 3, 3, 4 and 5 RF pulses, respectively, were used. The overall success was 37.14% (95% confidence interval, 11.83% to 62.45%). Patients are asymptomatic for 14 +/- 2 months., Conclusions: Postinfarction pericardial adherence does not preclude epicardial mapping and ablation to control VT related to an epicardial circuit in postinferior wall myocardial infarction.

We report the case of an 11-month-old child with incessant ventricular tachycardia who underwent two unsuccessful endocardial ablations with standard catheters and in whom the ventricular tachycardia was interrupted only during transthoracic epicardial catheter ablation. This report outlines the usefulness and safety of this novel approach in pediatric patients before surgery when endocardial ablation fails.

We report a case of a 63-year-old women with Chagas' disease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds of application and rendered noninducible afterwards. Two weeks after the procedure, a distinct morphology VT was induced by programmed ventricular stimulation, and the patient was started on amiodarone, remaining asymptomatic 12 months after the procedure.

Introduction: Postinfarction ventricular tachycardia (VT), anteroseptal aneurysm, and ventricular dysfunction are commonly associated and predict a poor long-term prognosis. Surgical left ventricular reconstruction, which includes double plication of the anterior and septal wall, can improve ventricular function. This article analyzes the long-term efficacy of such a procedure to control recurrence of VT in a group of 50 consecutive patients., Methods and Results: The study group consisted of 50 consecutive patients operated on between December 1986 and December 1994. The group comprised 44 men and 6 women. The mean age was 56+/-11 years. All patients had spontaneous VT following an anterior myocardial infarction. Twenty-five patients had two or more episodes of VT (eight presented as cardiac arrest, nine as syncope). Coronary artery disease was limited to the left anterior descending artery in 27 patients. An anteroseptal aneurysm was present in 49 patients. All patients had VT induced by programmed ventricular stimulation before surgery, and left ventricular reconstruction was performed without intraoperative mapping in all cases. Total mortality, VT recurrence, and sudden death rate were the endpoints of the study. In-hospital mortality was 8%. Postoperative left ventricular ejection fraction improved from 0.38 to 0.50 (P<0.05). Only two patients had postoperative inducible VT. Overall survival, VT recurrence rate, and sudden death rate were 73%, 12%, and 10%, respectively, after a median follow-up period of 6.25 years (0 to 8 years)., Conclusion: Visually guided left ventricular reconstruction with septal and anterior wall plicature can be utilized effectively to treat recurrent VT associated with postinfarction anteroseptal aneurysm.

Introduction: An epicardial site of origin of ventricular tachycardia (VT) may explain unsuccessful endocardial radiofrequency (RF) catheter ablation. A new technique to map the epicardial surface of the heart through pericardial puncture was presented recently and opened the possibility of using epicardial mapping to guide endocardial ablation or epicardial catheter ablation. We report the efficacy and safety of these two approaches to treat 10 consecutive patients with VT and Chagas' disease., Methods and Results: Epicardial mapping was carried out with a regular steerable catheter introduced into the pericardial space. An epicardial circuit was found in 14 of 18 mapable VTs induced in 10 patients. Epicardial mapping was used to guide endocardial ablation in 4 patients and epicardial ablation in 6. The epicardial earliest activation site occurred 107+/-60 msec earlier than the onset of the QRS complex. At the epicardial site used to guide endocardial ablation, earliest activation occurred 75+/-55 msec before the QRS complex. Epicardial mid-diastolic potentials and/or continuous electrical activity were seen in 7 patients. After 4.8+/-2.9 seconds of epicardial RF applications, VT was rendered noninducible. Hemopericardium requiring drainage occurred in 1 patient; 3 others developed pericardial friction without hemopericardium. Patients remain asymptomatic 5 to 9 months after the procedure. Interruption during endocardial pulses occurred after 20.2+/-14 seconds (P = 0.004), but VT was always reinducible and the patients experienced a poor outcome., Conclusion: Epicardial mapping does not enhance the effectiveness of endocardial pulses of RF. Epicardial applications of RF energy can safely and effectively treat patients with VT and Chagas' disease.

Introduction: A possible epicardial site of origin may be the reason for unsuccessful endocardial application of radiofrequency energy to control recurrent ventricular tachycardia. This study tests the feasibility and safety of a new epicardial mapping technique in patients with Chagas' disease and recurrent ventricular tachycardia., Methods and Results: Epicardial mapping was performed through a pericardial puncture as an epidural introducer needle was advanced into the pericardial space under fluoroscopic guidance. Medium contrast was injected to demonstrate the position of the needle tip, and a guidewire was introduced until its tip lay within the pericardial space. A 8-French Hemaquet was advanced and 4-mm deflectable tip catheter introduced into the pericardial sac to map the right and left ventricular epicardium. Transthoracic echocardiographic monitoring was performed on the day of the procedure and on the day of hospital discharge. The pericardial space was reached in all patients with no complications. Electrophysiologic data suggesting the existence of an epicardial circuit was found in one patient. No complications occurred during the hospitalization period., Conclusion: Epicardial mapping can be safely performed through a pericardial puncture in the electrophysiology laboratory.

Unlabelled: The aim of the study was to register the prevalence of late potentials (LP) in patients with chronic Chagas' heart disease (CCD) and the relationship with sustained ventricular tachycardia (SVT). 192 patients (96 males), mean age 42.9 years, with CCD were studied through a Signal Averaged ECG using time domain analysis. According to presence or absence of bundle branch block (BBB) and SVT, four groups of patients were created: Group I (n = 72): without SVT (VT-) and without BBB (BBB-): Group II (n = 27): with SVT (VT+) and BBB-; Group III (n = 63): VT- and with BBB (BBB+); and Group IV (N = 30): VT+ and BBB+. The LP was admitted, with 40 Hz filter, in the groups without BBB using standard criteria of the method. In the group with BBB, the root-mean-square amplitude of the last 40 ms (RMS) < = 14 microV was considered as an indicator of LP., Results: In groups I and II, LP was present in 21 (78%) of the patients with SVT and in 22 (31%) of the patients with SVT (p < 0.001), with Sensitivity (S) 78%; Specificity (SP) 70% and Accuracy (Ac) 72%. LP was present in 30 (48%) of the patients without and 20 (67%) of the patients with SVT, in groups III and IV. p = 0.066, with S = 66%; SP = 52%; and Ac = 57%. In the follow-up, there were 4 deaths unrelated to arrhythmic events, all of them did not have LP. Eight (29.6%) of the patients from group II and 4 (13%) from group IV presented recurrence of SVT and 91.6% of these patients had LP., Conclusions: LP occurred in 77.7% of patients with SVT and without BBB. In the groups with BBB, there was association of LP with SVT in 66.6% of the cases. The recurrence of SVT was patient in 21% of the cases from which 91.6% had LP.