High-power, short-duration ablation in the coronary sinus: clinical cases and preliminary observations on swine hearts

Purpose Coronary sinus-related arrhythmias are common; however, it is difficult to perform radiofrequency (RF) ablation at these sites efficiently and safely. High-power, short-duration ablation (HPSD) is a proven alternative strategy for pulmonary vein isolation (PVI); whether it can be applied to ablation of the coronary sinus is unknown. The purpose of this preliminary study was to evaluate the feasibility and safety of HPSD ablation in the coronary sinus. Methods Firstly, we demonstrated 4 clinical cases of 3 types of arrhythmias who had unsuccessful ablation with standard power initially, but received successful ablations with HPSD. Secondly, RF ablation was performed in the coronary sinus ostium (CSO) and middle cardiac vein (MCV) of 4 in vitro swine hearts. Two protocols were compared: HPSD (45 W/5 S×5 rounds) and a conventional strategy that used low-power, long-duration ablation (LPLD: 25 W/10 S ×5 rounds). The total duration of HPSD protocol was 25 s, and which of LPLD was 50 s. Results A total of 28 lesions were created. HPSD can produce longer, wider, deeper, and larger lesions than LPLD. This difference was more pronounced when the ablation was in the MCV. One instance of steam pop occurred during LPLD in the MCV. Conclusions HPSD is an effective alternative strategy for ablation in coronary sinus according to clinical applications and preliminary animal study. However, the safety needs to be further evaluated based on more animal and clinical studies.

Vein of Marshall visualization in cardiac computed tomography

The oblique vein of the left atrium (vein of Marshall) is a small vessel that descends obliquely on the back of the left atrium and ends in the coronary sinus near the area where great cardiac vein continues into the coronary sinus. Its cannulation can be useful, e.g. before selected electrophysiology procedures such as paroxysmal focal atrial fibrillation ablation. Because the vein of Marshall should also be avoided at the site of the implantation of the left ventricle lead, knowledge about its existence, position or diameters could be useful. There is a lack of complex data about the possibilities of visualizing the vein of Marshall in cardiac computed tomography. Methods 354 patients were included into the research. Cardiac computed tomography (Aquilion 64, Toshiba: 64 slices, 0.5 mm; retrospective gating; contrast enhanced) was performed for all of the patients. A precise retrospective analysis of the CT data in all phases (every 10%) of the cardiac cycle during post processing was performed including searching for the target vein by using Vitrea workstations (Vital Images). Both multi planar reformatted reconstructions (MPR) and 3D volume renderings were used. The analyses were performed by two experienced researchers (more than 200 coronary venous system analyses previously performed). Results The vein of Marshall was found in 66 of the 354 patients (16.6%). An example of the visualization is presented in the figure below (MPR and 3D volume rendering). Its ostium to coronary sinus was found an average of 42.6±10.8 mm from the coronary sinus ostium to the right atrium. This value was statistically higher (p=0.0082) in the men (45.3±11.2) compared to the women (38.5±9.7). The vein of Marshall is a small vessel; its average diameter was 1.8±0.8 mm and length of the visible vessel that was measured was 8.7±7.5 mm. It was visualized statistically more frequently (p=0.0009) in the end-systolic phases (30–40–50% RR; 68.85% cases) compared to the end-diastolic phases (70–80% RR; 21.31% cases). Occasionally, it was optimally visualized in the other phases (9.83%). Conclusion It is possible to visualize the vein of Marshall using cardiac computed tomography. Because it exists in about 20% of population, during visualization, special attention needs to paid to obtaining quality images in CT especially in the end-systolic phases. Vein of Marshall imaging (VR, MPR) Funding Acknowledgement Type of funding source: None

Right Atrial Collision Time (RACT): a novel marker of propensity for typical atrial flutter

Background The risk of typical atrial flutter (AFL) is increased by factors that increase right atrial (RA) size or cause scarring to reduce conduction velocity. These characteristics ensure the macro re-entrant wave front does not meet its refractory tail. The time taken to traverse the circuit would take account of both of these characteristics (being equal to distance divided by velocity), and may provide a superior marker of propensity to develop AFL. Purpose To investigate right atrial collision time (RACT) as a marker of typical AFL. Methods This single centre, prospective study recruited consecutive typical AFL ablation cases that were in sinus rhythm. Controls were consecutive cases other than atrial fibrillation and >50 years of age. Exclusion criteria for both groups were a prior ablation in the RA and class I and III antiarrhythmics. While pacing the coronary sinus ostium at 600 ms, a local activation time map was created to locate the latest collision point on the anterolateral wall, excluding the RA appendage (Figure 1). This RACT approximates half a revolution. Results The AFL group's (n=34) mean RACT was 132.5±15.06 vs 98.7±12.23ms in the controls (n=40) (p<0.01). No significant difference was observed for age (mean 65.6 vs 62.6 (p=0.18)), male (68.8% vs 60% (p=0.59)), body surface area (mean 2.1 vs 2.03 m2 (p=0.24)). The RACT also proved to be a superior marker than the echocardiographic measurement of right atrial area in an apical four chamber view (mean 17.8 vs 16.3 cm2 (p=0.21).A ROC curve indicated an AUC of 0.97 (95% CI: 0.93–1.0, p<0.01). A RACT cut-off of 120 ms had a specificity of 99% and a sensitivity of 75%. Conclusion RACT is a novel and promising marker of propensity for typical AFL. The ability to predict AFL would be of significant clinical value given the risk of stroke and frequent need for ablation. Funding Acknowledgement Type of funding source: None

Single-Stage Fontan Operation in a Patient With Coronary Sinus Ostium Atresia

An eight-year-old boy with tricuspid atresia was found to have atretic coronary sinus ostium during cardiac catheterization. Single-stage extracardiac fenestrated Fontan operation was performed with surgical unroofing of the coronary sinus into the left atrium to avoid the risk of cardiac congestion.