Contact Force in Atrial Fibrillation: Role of Atrial Rhythm and Ventricular Contractions: Co-Force Atrial Fibrillation Study

In an experimental model, variable and intermittent contact force (CF) resulted in a significant decrease in lesion volume. In humans, variability of CF during pulmonary vein isolation has not been characterized. Methods and Results-In 20 consecutive patients undergoing CF-guided circumferential pulmonary vein isolation, 914 radiofrequency applications (530 in sinus rhythm and 384 in atrial fibrillation) were analyzed. The variability of the 60% CF range (CF60%) was 17 ± 9.6 g. Hundred seventy-one (19%) applications were delivered with constant, 717 (78%) with variable, and 26 (3%) with intermittent CF. The mean CF and force-time integral were significantly higher during applications with variable than with intermittent or constant CF. There was no significant difference in CF variability, CF60% variability, and force-time integral between applications delivered in sinus rhythm and atrial fibrillation. The main reasons for CF variability were systolo-diastolic heart movement (29%) and respiration (27%). In 10 additional patients, during adenosine-induced atrioventricular block, the minimum CF significantly increased at 19 sites (5.3 ± 4.4 versus 13.4 ± 5.9 g; P < 0.001) and at 16 sites intermittent or variable CF became constant. At only 1 site systolo-diastolic movement remained the main reason for variable CF. Conclusions-CF during pulmonary vein isolation remains highly variable despite efforts to optimize contact. CF and CF parameters were similar during sinus rhythm and atrial fibrillation. The main reasons for CF variability are systolodiastolic heart movement and respiration. The systolo-diastolic peaks and nadirs of CF are because of ventricular contractions at the large majority of pulmonary vein isolation sites.

Comparison of contrast enhanced three dimensional echocardiography with MIBI gated SPECT for the evaluation of left ventricular function

Background. In clinical practice and in clinical trials, echocardiography and scintigraphy are used the most for the evaluation of global left ejection fraction (LVEF) and left ventricular (LV) volumes. Actually, poor quality imaging and geometrical assumptions are the main limitations of LVEF measured by echocardiography. Contrast agents and 3D echocardiography are new methods that may alleviate these potential limitations. Methods. Therefore we sought to examine the accuracy of contrast 3D echocardiography for the evaluation of LV volumes and LVEF relative to MIBI gated SPECT as an independent reference. In 43 patients addressed for chest pain, contrast 3D echocardiography (RT3DE) and MIBI gated SPECT were prospectively performed on the same day. The accuracy and the variability of LV volumes and LVEF measurements were evaluated. Results. Due to good endocardial delineation, LV volumes and LVEF measurements by contrast RT3DE were feasible in 99% of the patients. The mean LV end-diastolic volume (LVEDV) of the group by scintigraphy was 143 65 mL and was underestimated by triplane contrast RT3DE (128 60 mL; p < 0.001) and less by full-volume contrast RT3DE (132 62 mL; p < 0.001). Limits of agreement with scintigraphy were similar for triplane andfull-volume, modalities with the best results for full-volume. Results were similar for calculation of LV end-systolic volume (LVESV). The mean LVEF was 44 16% with scintigraphy and was not significantly different with both triplane contrast RT3DE (45 15%) and full-volume contrast RT3DE (45 15%). There was an excellent correlation between two different observers for LVEDV, LVESV and LVEF measurements and inter observer agreement was also good for both contrast RT3DE techniques. Conclusion. Contrast RT3DE allows an accurate assessment of LVEF compared to the LVEF measured by SPECT, and shows low variability between observers. Although RT3DE triplane provides accurate evaluation of left ventricular function, RT3DE full-volume is superior to triplane modality in patients with suspected coronary artery disease. © 2009 Cosyns et al; licensee BioMed Central Ltd.