Peri-Balloon Leak Flow Velocity Assessed by Intra-Cardiac Echography Predicts Pulmonary Vein Electrical Gap　- Intra-Cardiac Echography-Guided Contrast-Free Cryoballoon Ablation.

BACKGROUND: The use of iodine contrast agents is one possible limitation in cryoballoon ablation (CBA) for atrial fibrillation (AF). This study investigated intracardiac echography (ICE)-guided contrast-free CBA.Methods and Results:The study was divided into 2 phases. First, 25 paroxysmal AF patients (Group 1) underwent CBA, and peri-balloon leak flow velocity (PLFV) was assessed using ICE and electrical pulmonary vein (PV) lesion gaps were assessed by high-density electroanatomical mapping. Then, 24 patients (Group 2) underwent ICE-guided CBA and were compared with 25 patients who underwent conventional CBA (historical controls). In Group 1, there was a significant correlation between PLFV and electrical PV gap diameter (r=-0.715, P<0.001). PLFV was higher without than with an electrical gap (mean [±SD] 127.0±28.6 vs. 66.6±21.0 cm/s; P<0.001) and the cut-off value of PLFV to predict electrical isolation was 105.7 cm/s (sensitivity 0.700, specificity 0.929). In Group 2, ICE-guided CBA was successfully performed with acute electrical isolation of all PVs and without the need for "rescue" contrast injection. Atrial tachyarrhythmia recurrence at 6 months did not differ between ICE-guided and conventional CBA (3/24 [12.5%] vs. 5/25 [20.0%], respectively; P=0.973, log-rank test). CONCLUSIONS: PLFV predicted the presence of an electrical PV gap after CBA. ICE-guided CBA was feasible and safe, and could potentially be performed completely contrast-free without a decrease in ablation efficacy.

Techniques for reducing air bubble intrusion into the left atrium during radiofrequency catheter and cryoballoon ablation procedures: An ex vivo study with a high-resolution camera.

BACKGROUND: Air embolisms are serious complications during catheter ablation procedures. OBJECTIVES: The aims of the present study were to determine when air bubbles enter the left atrium (LA) during catheter ablation procedures and to identify techniques that reduce air bubble intrusion. METHODS: An ex vivo study was performed to monitor air bubbles using a silicone heart model and a high-resolution camera. In total, 280 radiofrequency catheter and cryoballoon ablation processes were tested. RESULTS: Small and large air bubbles were often observed during catheter ablation processes. Many small air bubbles arose during sheath flushing at fast speeds (15 mL/2 s) (median bubble number [quartiles]: 35 [20-53] for SL0, 35 [23-44] for Agilis, and 98 [91-100] for FlexCath) and during initial cryoballoon inflation/freezing/deflation (34 [22-47]). Large (≥1.5 mm) air bubbles were observed during Lasso catheter insertion (1 [0-1]), cryoballoon insertion (2 [1-2]), and initial inflation/freezing/deflation (1 [1-3]). Massive air bubbles were observed during Optima catheter insertion into the sheath using an inserter (10 [2-15]). Sheath flushing at slow speeds (15 mL/5 s) significantly reduced the number of air bubbles. Before cryoballoon insertion, temporary balloon inflation and air bubble removal from the inflated surface were most effective in reducing air bubble intrusions. Optima catheter insertion without an inserter significantly reduced large air bubble intrusion. CONCLUSION: Air bubbles entered the LA at specific times. Techniques such as sheath flushing at slow speeds, temporary cryoballoon inflation before insertion, inserting the Optima catheter without an inserter, and avoidance of negative pressure in the LA could reduce air bubble intrusion.

The importance of catheter stability evaluated by Visitag(TM) during pulmonary vein isolation.

BACKGROUND: The recurrence rates of atrial fibrillation (Af) after ablation are still high, and repeat procedures are required in these patients. The main reason for Af recurrence is the recovery of the conduction between the pulmonary veins and left atrium. The importance of catheter stability during the pulmonary vein isolation (PVI) is not well studied. PURPOSE: The purpose of this study was to evaluate the contact force (CF), stable ablation time, and power during conduction blocking lesion formation for PVI. METHODS: Thirty-two consecutive drug-refractory Af patients who underwent an initial PVI using CARTO 3 and Visitag were included. The CF, ablation time, force time integral (FTI), and ablation power were recorded by Visitag. Residual conduction gap points requiring touch-up ablation after an encircling linear ablation (R point), spontaneous reconnection points (S point), and dormant conduction points (D point) were considered as non-conduction blocking lesion points. Each ablation parameter for the non-conduction blocking lesion points was compared with the other lesion points. RESULTS: Twenty-one points in 16 patients were considered non-conduction blocking lesions. Ten were R, eight were S, and three were D points. The CF, ablation time, FTI, and power at the non-conduction blocking lesion points and other points were 12.0 g (7.0-21.5) and 12.0 g (9.0-16.0) (P = 0.9), 7.7 s (5.6-10.1) and 12.5 s (9.4-16.8) (P < 0.05), 103.0 g*s (62.0-174.5) and 149.0 g*s (104.0-213.0) (P < 0.05), and 30.0 W (22.5-30.0) and 30.0 W (30.0-30.0) (P = 0.06), respectively. CONCLUSIONS: Shorter ablation time recorded in Visitag lead to non-conduction blocking lesion.

Optical coherence tomography study of chronic-phase vessel healing after implantation of bare metal and paclitaxel-eluting self-expanding nitinol stents in the superficial femoral artery.

BACKGROUND: This study aimed to assess chronic-phase suppression of neointimal proliferation and arterial healing following paclitaxel-coated (PTX) and bare metal stent (BMS) implantation in the superficial femoral artery using optical coherence tomography (OCT). METHODS: Twenty-five patients with 68 stents underwent an 8-month OCT follow-up. Besides standard OCT variables, neointimal characterization and frequencies of peri-strut low-intensity area (PLIA), macrophage accumulation, and in-stent thrombi were evaluated. RESULTS: The mean neointimal thickness was significantly less with PTX stents (544.9±202.2 µm vs. 865.0±230.6 µm, p<0.0001). The covered and uncovered strut frequencies were significantly smaller and larger, respectively, in the PTX stent group vs. the BMS group (93.7% vs. 99.4%; p<0.0001, 4.0% vs. 0.4%; p<0.0001, respectively). Heterogeneous neointima was only observed in the PTX stent group (12.5% vs. 0%, p=0.017). The frequencies of PLIA and macrophage accumulation were significantly greater in the PTX stent group (87.2% vs. 67.6%, p=0.001 and 46% vs. 9.1%, p=0.003, respectively). CONCLUSION: After 8 months, reduced neointimal proliferation was observed with PTX stent implantation. On the other hand, delayed arterial healing was observed compared with BMS.

Reduction in coronary microvascular resistance through cardiac resynchronization and its impact on chronic reverse remodelling of left ventricle in patients with non-ischaemic cardiomyopathy.

AIMS: Left bundle branch block (LBBB) induces mechanical dyssynchrony, thereby compromising the coronary circulation in non-ischaemic cardiomyopathy. We sought to examine the effects of cardiac resynchronization therapy (CRT) on coronary flow dynamics and left ventricular (LV) function. METHODS AND RESULTS: Twenty-two patients with non-ischaemic cardiomyopathy (New York Heart Association class, III or IV; LV ejection fraction, ≤35%; QRS duration, ≥130 ms) were enrolled. One week after implantation of the CRT device, coronary flow velocity and pressure in the left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCx) were measured invasively, before and after inducing hyperemia by adenosine triphosphate administration, with two programming modes: sequential atrial and biventricular pacing (BiV) and atrial pacing in patients with LBBB or sequential atrial and right ventricular pacing in patients with complete atrioventricular block (Control). We assessed hyperemic microvascular resistance (HMR, mean distal pressure divided by hyperemic average peak velocity) and the relationship between the change in HMR and mid-term LV reverse remodelling. Hyperemic microvascular resistance was lower during BiV than during Control (LAD: 1.76 ± 0.47 vs. 1.54 ± 0.45, P < 0.001; LCx: 1.92 ± 0.42 vs. 1.73 ± 0.31, P = 0.003). The CRT-induced change in HMR of the LCx correlated with the percentage change in LV ejection fraction (R = -0.598, P = 0.011) and LV end-systolic volume (R = 0.609, P = 0.010) before and 6 months after CRT. CONCLUSION: Cardiac resynchronization therapy improves coronary flow circulation by reducing microvascular resistance, which might be associated with LV reverse remodelling.