RESUMEN
INTRODUCTION: While catheter tip/tissue contact has been shown to be an important determinant of ablative lesions in in vitro studies, the impact of contact on the outcomes of mapping and ablation in the intact heart has not been evaluated. METHODS AND RESULTS: Twelve dogs underwent atrial ablation guided by the Senesitrade mark robotic catheter remote control system. After intracardiac ultrasound (ICE) validation of contact force measured by an in-line mechanical sensor, the relationship between contact force and individual lesion formation was established during irrigated-tipped ablation (flow 17 mL/sec) at 15 watts for 30 seconds. Minimal contact by ICE correlated with force of 4.7 +/- 5.8 grams, consistent contact 9.9 +/- 8.6 grams and tissue tenting produced 25.0 +/- 14.0 grams. Conversely, catheter tip/tissue contact by ICE was predicted by contact force. A contact force of 10-20 and > or =20 grams generated full-thickness, larger volume ablative lesions than that created with <10 grams (98 +/- 69 and 89 +/- 70 mm(3) vs 40 +/- 42 mm(3), P < 0.05). Moderate (10 grams) and marked contact (15-20 grams) application produced 1.5 X greater electroanatomic map volumes that were seen with minimal contact (5 grams) (26 +/- 3 cm(3) vs 33 +/- 6, 39 +/- 3 cm(3), P < 0.05). The electroanatomic map/CT merge process was also more distorted when mapping was generated at moderate to marked contact force. CONCLUSION: This study shows that mapping and ablation using a robotic sheath guidance system are critically dependent on generated force. These findings suggest that ablative lesion size is optimized by the application of 10-20 grams of contact force, although mapping requires lower-force application to avoid image distortions.
Asunto(s)
Arritmias Cardíacas/diagnóstico , Mapeo del Potencial de Superficie Corporal/instrumentación , Cateterismo Cardíaco/instrumentación , Animales , Arritmias Cardíacas/fisiopatología , Modelos Animales de Enfermedad , Perros , Ecocardiografía , Diseño de Equipo , Fluoroscopía , PronósticoRESUMEN
INTRODUCTION: The purpose of this study was to examine tissue temperatures around pulmonary veins (PVs) during high intensity focused ultrasound (HIFU) balloon ablation for atrial fibrillation. The thermodynamics and extent of PV and phrenic nerve (PN) heating during HIFU ablation have not been established. METHODS AND RESULTS: Tissue temperatures were recorded from epicardial thermocouples at right superior (RS) PV orifice and PN in eight dogs undergoing 51 RSPV HIFU ablations (40 seconds, 40 W). Maximum tissue temperatures, reflected by 288 recording profiles, were negatively correlated with distance from balloon surface (r =-0.79, P < 0.001). Average maximum RSPV temperature was 56.8 +/- 16.8 degrees C (distance: 6.6 +/- 4.1 mm), resulting in full-thickness, circumferential PV isolation in 7 of 8 animals. Direct local mechanical heating restricted to the focused ultrasound zone showed temperature rise to > or =50 degrees C within 10 seconds to a maximum temperature of 82.6 +/- 8.9 degrees C (n = 31). Apparent conductive heating showed gradual heating patterns (<50 degrees C within 10 seconds) at greater distance. PN temperature at all recording sites was 45.0 +/- 11.3 degrees C (distance: 9.2 +/- 5.0 mm). Intentional PN injury (10 of 51 [19.6%] ablations), occurred at 63.7 +/- 16.0 degrees C with closest distance of 4.4 +/- 2.5 mm, which was closer than in PNs without injury (7.3 +/- 4.3 mm, P = 0.005). CONCLUSIONS: HIFU ablation is highly effective in generating temperatures needed for full-thickness, circumferential ablation through rapid direct mechanical heating. Gradual heating of surrounding tissue supports the presence of conductive heating. This study also discloses direct HIFU effects as the mechanism of PN injury occurring within 4-7 mm from balloon surface.
Asunto(s)
Fibrilación Atrial/terapia , Temperatura Corporal/efectos de la radiación , Quemaduras/prevención & control , Quemaduras/fisiopatología , Nervio Frénico/lesiones , Nervio Frénico/fisiopatología , Venas Pulmonares/fisiopatología , Terapia por Ultrasonido/efectos adversos , Animales , Fibrilación Atrial/fisiopatología , PerrosRESUMEN
BACKGROUND: Multiple factors create discrepancies between electroanatomic maps and merged, preacquired computed tomographic images used in guiding atrial fibrillation ablation. Therefore, a Carto-based 3D ultrasound image system (Biosense Webster Inc) was validated in an animal model and tested in 15 atrial fibrillation patients. METHODS AND RESULTS: Twelve dogs underwent evaluation using a newly developed Carto-based 3D ultrasound system. After fiducial clip markers were percutaneously implanted at critical locations in each cardiac chamber, 3D ultrasound geometries, derived from a family of 2D intracardiac echocardiographic images, were constructed. Point-source error of 3D ultrasound-derived geometries, assessed by actual real-time 2D intracardiac echocardiographic clip sites, was 2.1+/-1.1 mm for atrial and 2.4+/-1.2 mm for ventricular sites. These errors were significantly less than the variance on CartoMerge computed tomographic images (atria: 3.3+/-1.6 mm; ventricles: 4.8+/-2.0 mm; P<0.001 for both). Target ablation at each clip, guided only by 3D ultrasound-derived geometry, resulted in lesions within 1.1+/-1.1 mm of the actual clips. Pulmonary vein ablation guided by 3D ultrasound-derived geometry resulted in circumferential ablative lesions. Mapping in 15 patients produced modestly smaller 3D ultrasound versus electroanatomic map left atrial volumes (98+/-24 cm(3) versus 109+/-25 cm(3), P<0.05). Three-dimensional ultrasound-guided pulmonary vein isolation and linear ablation in these patients were successfully performed with confirmation of pulmonary vein entrance/exit block. CONCLUSIONS: These data demonstrate that 3D ultrasound images seamlessly yield anatomically accurate chamber geometries. Image volumes from the ultrasound system are more accurate than possible with CartoMerge computed tomographic imaging. This clinical study also demonstrates the initial feasibility of this guidance system for ablation in patients with atrial fibrillation.