Quantitative modeling of the accuracy in registering preoperative patient-specific anatomic models into left atrial cardiac ablation procedures.

PURPOSE: In cardiac ablation therapy, accurate anatomic guidance is necessary to create effective tissue lesions for elimination of left atrial fibrillation. While fluoroscopy, ultrasound, and electroanatomic maps are important guidance tools, they lack information regarding detailed patient anatomy which can be obtained from high resolution imaging techniques. For this reason, there has been significant effort in incorporating detailed, patient-specific models generated from preoperative imaging datasets into the procedure. Both clinical and animal studies have investigated registration and targeting accuracy when using preoperative models; however, the effect of various error sources on registration accuracy has not been quantitatively evaluated. METHODS: Data from phantom, canine, and patient studies are used to model and evaluate registration accuracy. In the phantom studies, data are collected using a magnetically tracked catheter on a static phantom model. Monte Carlo simulation studies were run to evaluate both baseline errors as well as the effect of different sources of error that would be present in a dynamic in vivo setting. Error is simulated by varying the variance parameters on the landmark fiducial, physical target, and surface point locations in the phantom simulation studies. In vivo validation studies were undertaken in six canines in which metal clips were placed in the left atrium to serve as ground truth points. A small clinical evaluation was completed in three patients. Landmark-based and combined landmark and surface-based registration algorithms were evaluated in all studies. In the phantom and canine studies, both target registration error and point-to-surface error are used to assess accuracy. In the patient studies, no ground truth is available and registration accuracy is quantified using point-to-surface error only. RESULTS: The phantom simulation studies demonstrated that combined landmark and surface-based registration improved landmark-only registration provided the noise in the surface points is not excessively high. Increased variability on the landmark fiducials resulted in increased registration errors; however, refinement of the initial landmark registration by the surface-based algorithm can compensate for small initial misalignments. The surface-based registration algorithm is quite robust to noise on the surface points and continues to improve landmark registration even at high levels of noise on the surface points. Both the canine and patient studies also demonstrate that combined landmark and surface registration has lower errors than landmark registration alone. CONCLUSIONS: In this work, we describe a model for evaluating the impact of noise variability on the input parameters of a registration algorithm in the context of cardiac ablation therapy. The model can be used to predict both registration error as well as assess which inputs have the largest effect on registration accuracy.

Mapeamento endocárdico e epicárdico para a ablação do substrato arritmogênico de pacientes com cardiomiopatia chagásica e taquicardia ventricular refratária ao tratamento farmacológico / Epicardial and endocardial mapping for arrhythmogenic substrate catheter ablation in patients with Chagas cardiomyopathy and refractory ventricular tachycardia

Objetivo: Avaliar a segurança e a eficácia da ablação por cateter de substrato endocárdico e epicárdico de pacientes com cardiomiopatia chagásica e taquicardia ventricular refratária ao tratamento farmacológico. Método: 34 pacientes foram incluídos no estudo. Durante o ritmo sinusal, foi realizado o mapeamento eletroanatômico (CARTO-XP) endoepicárdico de voltagem utilizando critérios padronizados (cicatriz < 1,5 mV). A estimulação programada foi usada para a indução de taquicardia ventricular e as arritmias estáveis foram submetidas a mapeamento de ativação e encarrilhamento. Nas arritmias instáveis, a saída do circuito foi definida pela estimulação e o mapeamento (pace mapping) na borda da cicatriz. A ablação foi realizada após definição do circuito e do substrato pelas técnicas descritas. Resultados: Foram realizados 34 procedimentos, com sucesso imediato de 79 por cento. Foi encontrada cicatriz epicárdica em 88 por cento dos pacientes. Não houve tamponamento cardíaco ou qualquer outra complicação grave relacionada ao procedimento. No seguimento de 12 meses, a taxa de recorrência foi de 15 por cento sem indução de taquicardia ventricular e três pacientes morreram devido a progressão da falência cardíaca. Conclusão: A ablação endocárdica e epicárdica foi segura e efetiva para o controle da taquicardia ventricular em pacientes com doença de Chagas.

Objective: Assess the safety and efficacy of endocardial and epicardial substrate catheter mapping and ablation of refractory ventricular tachycardia in patients with Chagas Disease. Patients and Methods: 34 patients were included in this study. During sinus rhythm, patients underwent epicardial and endocardial voltage electroanatomic mapping (CARTO) using standardized criteria (scar < 1.5 mV). Programmed ventricular stimulation was used to induce ventricular tachycardia and stable rhythms were submitted to activation and entrainment mapping. Exit of unstable arrhythmias was defined by stimulation and mapping (pace-mapping) in the scar border zone. Ablation was performed after definition of the circuit and substrate by the reported techniques. Results: 34 procedures were performed and immediate success was achieved in 79 percent. Epicardial scar was observed in 88 percent. There was no cardiac tamponade or major complications related to the procedure. During the 12 month follow-up the recurrence rate was 15 percent in the patients without ventricular tachycardia induction and three patients died due to progressive heart failure. Conclusion: In the study population, catheter ablation using epicardial and endocardial approach was safe and effective in ventricular tachycardia control in chagasic patients.

Simultaneous epicardial and endocardial substrate mapping and radiofrequency catheter ablation as first-line treatment for ventricular tachycardia and frequent ICD shocks in chronic chagasic cardiomyopathy.

BACKGROUND AND AIMS: Slow conduction scarred areas are related with ventricular tachycardia (VT) arrhythmogenesis in nonischemic cardiomyopathy. The purpose of this study was to characterize the substrate in both epicardial and endocardial surfaces of the left ventricle and to evaluate the effectiveness of substrate mapping and ablation for VT in Chagas cardiomyopathy. METHODS AND RESULTS: Seventeen patients were evaluated prospectively using a simultaneous epicardial and endocardial electroanatomical substrate mapping and ablation. With a mean of 201 +/- 94 epicardial and 169 +/- 77 endocardial points, the epicardial voltage areas < or =0.5 mV were 56.8 +/- 40.6 (range 4.4 to 154.8 cm(2)) as compared to 22.5 +/- 15.8 cm(2) (range 5.4 to 61.0 cm(2); p = 0.004) in the endocardium. Analyzing the epicardial surface, there was a strong correlation between the bipolar voltage electrograms and the electrogram duration at the epicardium during sinus rhythm (r = 0.897, p < 0.0001). Acute success was obtained in 83.3% of patients with no serious complications. At the end of follow-up from 14 patients with acute success, 11 (78.6%) had been event-free based on implantable cardioverter defibrillator (ICD) interrogation logs. CONCLUSION: Chronic Chagas cardiomyopathy patients have larger epicardial as compared to endocardial substrate areas. Combined epicardial endocardial substrate mapping and ablation during sinus rhythm proves effective in preventing VT recurrences and appropriate ICD therapies.

Distortion of right superior pulmonary vein anatomy by balloon catheters as a contributor to phrenic nerve injury.

INTRODUCTION: Cryothermal, HIFU, and laser catheter-based balloon technologies have been developed to simplify ablation for AF. Initial enthusiasm for their widespread use has been dampened by phrenic nerve (PN) injury. The interaction between PN and pulmonary vein (PV) geometry contributing to PN injury is unclear. METHODS AND RESULTS: After right thoracotomy, the PN course along the epicardial right atrial surface was mapped directly in 10 dogs. The location of the PN and its relationship with the right superior (RS) PV, and potential RSPV surface distortions after balloon inflation were established by electroanatomic mapping. In 5 dogs, the PN was captured within the RSPV, but could not be stimulated in the remaining 5 dogs. The distance between the RSPV and the PN was significantly shorter in the captured group than in the noncaptured group (6.3 +/- 3.1 mm vs 10.2 +/- 3.2 mm, P < 0.001). Importantly, 96% of the captured sites within the RSPV were observed at a distance >5 mm into the PV. The inflated balloon surface anteriorly extended 5.6 +/- 3.7 mm outside the PV diameter, with distortion of anatomy narrowing the distance from the balloon surface to the PN to 4.8 +/- 2.3 mm. (Distance of the original RSPV-to-PN: 9.4 +/- 2.7 mm, P < 0.001.) CONCLUSION: PN injury with balloon technologies may stem from anatomic distortion of the PV orifice/PN relationship, through increasing contact or shortening the relative distance between the ablation site and the PN, even without displacement of the balloon into the PV. These data are important in the refinement of these technologies to improve procedural safety.

Percutaneous epicardial left atrial appendage closure: preliminary results of an electrogram guided approach.

BACKGROUND: Pharmacologic therapies to prevent stroke in atrial fibrillation (AF) have numerous limitations, prompting the development of device-based therapies. We investigated whether an electrogram-based approach using a novel hollow suture can safely capture and ligate the left atrial appendage (LAA). METHODS AND RESULTS: A novel system for closure of the LAA within the confines of the closed pericardium with a single sheath puncture was tested in 4 dogs. The tool used to grasp the appendage was fitted with electrodes and utilized electrical navigation to identify and confirm LAA capture. A hollow suture preloaded with a mechanical support wire to permit its manipulation and fluoroscopic visualization was advanced over the grasper, and the wire removed after the suture was positioned. The LAA was successfully closed in all dogs. In 2 dogs, after closure, a thoracotomy was performed and the LAA amputated without bleeding, confirming closure integrity. Necropsy confirmed closure in all animals. CONCLUSIONS: Using electrical navigation, percutaneous epicardial LAA ligation with a remotely tightened suture was performed successfully within the confines of the intact pericardial space. This technique may allow decreasing the risk of stroke in AF patients without the need for thoracotomy or an endocardially placed prosthetic device.

Dispositivos eletrônicos implantáveis no tratamento de pacientes com cardiomiopatia chagásica crônica / Implantable electronical devices in the treatment of patients with chronic Chagas cardiomyopathy

A doença de Chagas é importante causa de mortalidade em regiões endêmicas. Uma das principais manifestações da afecção é o envolvimento cardíaco. Na fase crônica da doença, como resultado de degeneração e fibrose miocárdica, podem ocorrer bradiarritmias e insuficiência cardíaca, bem como desenvolver-se o subtrato para arrítmias ventriculares. Morte cardíaca súbita são as principais causas de óbito nesses pacientes. O uso de dispositivos eletrônicos implantáveis para tratamento de bradi e taquiarritmias tem importante papel na prevenção de morte súbita nesses pacientes. Neste artigo, será realizada uma revisão da utilização dos diferentes dispositivos da doença de Chagas.

Estudo comparativo entre oxcarbazepina e carbamazepina contra crises convulsivas tônico-clônicas induzidas por eletrochoque em ratos / Effects of Oxcarbazepine and Carbamazepine as anticonvulsivants induced by electric shock in rats

O trabalho visa comparar a eficácia anticonvulsivante da oxcarbazepina e da carbamazepina e a relaçao dose-efeito das mesmas. Foram utilizados 64 ratos albinos Wistar divididos em sete grupos, que receberam doses de OCBZ e CBZ em diferentes concentraçöes, sendo submetidos 30 minutos depois a eletrochoque transcorneal de 100V po 0,2 segundos, sendo observado o período de latência e de início das crises convulsivas tônico-clônicas...