Relationship between complex fractionated electrograms (CFE) and dominant frequency (DF) sites and prospective assessment of adding DF-guided ablation to pulmonary vein isolation in persistent atrial fibrillation (AF).

BACKGROUND: Sites of high DF are potential targets for AF ablation, but it is unknown if addition of DF ablation can improve procedural outcome. OBJECTIVES: We sought to (1) examine the relationship between DF sites and complex fractionated electrograms (CFE) and (2) prospectively assess the long-term outcome of adding DF ablation to pulmonary vein antral isolation (PVAI) for persistent AF. METHODS: First, 20 patients with persistent AF who underwent previous CFE-guided ablation and who had AF terminate during ablation were studied retrospectively (group I). Bipolar, 8-second electrograms were collected by a circular catheter (288 ± 86 points/map). The EnSite NavX system allows for automated display of both CFE and DF maps. Electrograms with cycle length <120 ms were considered CFE and were compared to DF sites > 8 Hz (direct inverse relationship). Sites of AF termination were related to CFE and DF sites. Based on these observations, 30 different patients (group II) with persistent AF prospectively underwent DF-guided ablation plus PVAI. They were followed every 3 months for 1 year (visit, Holter, ECG). These patients were compared to case-matched controls undergoing PVAI alone (group III). RESULTS: In group I, there was a significant, inverse correlation between DF and CFE values at each point (r =-0.24, P < 0.001). DF surface area was less than CFE area (27 ± 5 cm(2) vs 34 ± 4 cm(2) , P = 0.03). CFE sites overlapped 48 ± 27% with the DF surface area. Nonoverlapping CFE sites were contiguous to DF sites. AF termination occurred where DF and CFE overlapped, and at these sites, DF was always greater than the mean DF for the map. In group II, all DF sites above the mean value were prospectively ablated during AF. AF termination was noted in only 2/30 (7%) patients. After DF ablation, PVAI was performed and termination increased to 4/30 patients (14%). At 1 year, freedom from atrial arrhythmia > 30 seconds occurred in 57% of DF+PVAI compared to 60% in patients receiving PVAI alone (P = 0.18). CONCLUSIONS: DF and CFE regions overlap only about 50%. AF termination retrospectively occurred on overlapping CFE/DF sites where DF was above the mean. However, prospective ablation of DF sites plus PVAI resulted in low AF termination rates, and did not improve 1 year success over PVAI alone.

Treatment planning and dose analysis for interstitial photodynamic therapy of prostate cancer.

With the development of new photosensitizers that are activated by light at longer wavelengths, interstitial photodynamic therapy (PDT) is emerging as a feasible alternative for the treatment of larger volumes of tissue. Described here is the application of PDT treatment planning software developed by our group to ensure complete coverage of larger, geometrically complex target volumes such as the prostate. In a phase II clinical trial of TOOKAD vascular targeted photodynamic therapy (VTP) for prostate cancer in patients who failed prior radiotherapy, the software was used to generate patient-specific treatment prescriptions for the number of treatment fibres, their lengths, their positions and the energy each delivered. The core of the software is a finite element solution to the light diffusion equation. Validation against in vivo light measurements indicated that the software could predict the location of an iso-fluence contour to within approximately +/-2 mm. The same software was used to reconstruct the treatments that were actually delivered, thereby providing an analysis of the threshold light dose required for TOOKAD-VTP of the post-irradiated prostate. The threshold light dose for VTP-induced prostate damage, as measured one week post-treatment using contrast-enhanced MRI, was found to be highly heterogeneous, both within and between patients. The minimum light dose received by 90% of the prostate, D(90), was determined from each patient's dose-volume histogram and compared to six-month sextant biopsy results. No patient with a D(90) less than 23 J cm(-2) had complete biopsy response, while 8/13 (62%) of patients with a D(90) greater than 23 J cm(-2) had negative biopsies at six months. The doses received by the urethra and the rectal wall were also investigated.

Point-by-point pulmonary vein antrum isolation guided by intracardiac echocardiography and 3D mapping and duty-cycled multipolar AF ablation: effect of multipolar ablation on procedure duration and fluoroscopy time.

PURPOSE: Pulmonary vein antrum isolation (PVAI) guided by intracardiac echocardiography and a roaming circular mapping catheter is an effective treatment modality for atrial fibrillation. Unfortunately, the complexity of this technique leads to long procedure times and high fluoroscopy exposure. Single-catheter multipolar ablation holds the promise to reduce these parameters. This study examined the effect of the conventional point-by-point PVAI with that of single-catheter multipolar ablation on the procedural characteristics and clinical outcomes of atrial fibrillation ablation. METHODS: Referred patients underwent PVAI guided by a magnetic-based 3D mapping (CARTO 3(®) System; group 1) or duty-cycled multipolar AF ablation using the pulmonary vein ablation catheter (PVAC, group 2) between June 2010 and May 2011. RESULTS: Data were analyzed from 19 patients in group 1 and 31 patients in group 2. There was no significant difference in the length of the procedure between the two groups (135 ± 26 vs 125 ± 25 min, P = 0.20). Patients who underwent ablation using PVAC spent significantly less time in the procedure room pre- and post-procedure than those who underwent conventional PVAI (205 ± 38 vs 179 ± 30 min, P = 0.02) and had a significantly shorter fluoroscopy exposure (50 ± 16 vs 36 ± 14 min, P = 0.003) and radiofrequency energy delivery time (54 ± 26 vs 32 ± 33 min, P = 0.02). No differences in safety and efficacy were seen between the groups. CONCLUSIONS: Single-catheter multipolar AF ablation was associated with significantly lower fluoroscopy duration, radiofrequency energy delivery time, and the time the patient spent in the procedure room before and after ablation, although measured short-term clinical outcomes were similar.

CARTO-guided vs. NavX-guided pulmonary vein antrum isolation and pulmonary vein antrum isolation performed without 3-D mapping: effect of the 3-D mapping system on procedure duration and fluoroscopy time.

PURPOSE: Pulmonary vein antrum isolation (PVAI) guided by intracardiac echocardiography and a roaming circular mapping catheter is an effective treatment modality for atrial fibrillation. Unfortunately, the complexity of this technique leads to long procedure times and high fluoroscopy exposure. This study examined the effect of two different mapping systems on the procedural characteristics and clinical outcomes of PVAI for atrial fibrillation. METHODS: Referred patients underwent PVAI using a magnetic-based 3-dimensional (3-D) mapping (CARTO® System; group 1), a current-based system (EnSite NavX™; group 2), or fluoroscopy without 3-D mapping (group 3) between February 2004 and November 2009. RESULTS: Data were analyzed from 71 patients in group 1, 165 patients in group 2, and 197 patients in group 3. Baseline characteristics and measured long-term outcomes did not differ between the groups. Although patients in group 1 were more likely to undergo a concurrent flutter ablation (P = 0.01), they had significantly shorter procedure time, fluoroscopy time, and radiofrequency energy delivery time compared with group 2 and 3 patients. No difference was detected among the groups with respect to recurrence, mean time to recurrence, or number of PVAI procedures. CONCLUSIONS: Use of a magnetic-based 3-D mapping system, which allows precise spatial localization of the ablation catheter, was associated with significantly lower procedure time, fluoroscopy duration, and radiofrequency energy delivery time during catheter ablation for atrial fibrillation compared with a current-based system and ablation performed without 3-D mapping, although measured short- and long-term clinical outcomes were similar.