Description: Background— Normal coronary blood flow is principally determined by a backward-traveling decompression (suction) wave in diastole. Dyssynchronous chronic heart failure may attenuate suction, because regional relaxation and contraction overlap in timing. We hypothesized that biventricular pacing, by restoring left ventricular (LV) synchronization and improving LV relaxation, might increase this suction wave, improving coronary flow. Method and Results— Ten patients with chronic heart failure (9 males; age 65±12; ejection fraction 26±7%) with left bundle-branch block (LBBB; QRS duration 174±18 ms) were atriobiventricularly paced at 100 bpm. LV pressure was measured and wave intensity calculated from invasive coronary flow velocity and pressure, with native conduction (LBBB) and during biventricular pacing at atrioventricular (AV) delays of 40 ms, 120 ms, and separately preidentified hemodynamically optimal AV delay. In comparison with LBBB, biventricular pacing at separately preidentified hemodynamically optimal AV delay (BiV-Opt) enhanced coronary flow velocity time integral by 15% (7%–25%) ( P =0.007), LV dP/dt max by 15% (10%–21%) ( P =0.005), and neg dP/dt max by 17% (9%–22%) ( P =0.005). The cumulative intensity of the diastolic backward decompression (suction) wave increased by 26% (18%–54%) ( P =0.005). The majority of the increase in coronary flow velocity time integral occurred in diastole (69% [41%–84% ]; P =0.047). The systolic compression waves also increased: forward by 36% (6%–49%) ( P =0.022) and backward by 38% (20%–55%) ( P =0.022). Biventricular pacing at AV delays of 120 ms generated a smaller LV dP/dt max (by 12% [5%–23% ], P =0.013) and neg dP/dt max (by 15% [8%–40% ]; P =0.009) increase than BiV-Opt, against LBBB as reference; BiV-Opt and biventricular pacing at AV delays of 120 ms were not significantly different in coronary flow velocity time integral or waves. Biventricular pacing at AV delays of 40 ms was no different from LBBB. Conclusions— When biventricular pacing improves LV contraction and relaxation, it increases coronary blood flow velocity, predominantly by increasing the dominant diastolic backward decompression (suction) wave.

Description: Aims Recurrent arrhythmias after ablation procedures are often caused by recovery of ablated tissue. Robotic catheter manipulation systems increase catheter tip stability which improves energy delivery and could produce more transmural lesions. We tested this assertion using bipolar voltage attenuation as a marker of lesion quality comparing robotic and manual circumferential pulmonary vein ablation for atrial fibrillation (AF). Methods and results Twenty patients were randomly assigned to robotic or manual AF ablation at standard radiofrequency (RF) settings for our institution (30 W 60 s manual, 25 W 30 s robotic, R30). A separate group of 10 consecutive patients underwent robotic ablation at increased RF duration, 25 W for 60 s (R60). Lesions were marked on an electroanatomic map before and after ablation to measure distance moved and change in bipolar electrogram amplitude during RF. A total of 1108 lesions were studied (761 robotic, 347 manual). A correlation was identified between voltage attenuation and catheter movement during RF (Spearman's rho –0.929, P 〈 0.001). The ablation catheter was more stable during robotic RF; 2.9 ± 2.3 mm (R30) and 2.6 ± 2.2 mm (R60), both significantly less than the manual group (4.3 ± 3.0 mm, P 〈 0.001). Despite improved stability, there was no difference in signal attenuation between the manual and R30 group. However, there was increased signal attenuation in the R60 group (52.4 ± 19.4%) compared with manual (47.7 ± 25.4%, P = 0.01). When procedures under general anaesthesia (GA) and conscious sedation were analysed separately, the improvement in signal attenuation in the R60 group was only significant in the procedures under GA. Conclusions Robotically assisted ablation has the capability to deliver greater bipolar voltage attenuation compared with manual ablation with appropriate selection of RF parameters. General anaesthesia confers additional benefits of catheter stability and greater signal attenuation. These findings may have a significant impact on outcomes from AF ablation procedures.

Description: Patients with atrial fibrillation (AF) are at an increased risk of ischaemic stroke. The efficacy of stroke prevention with vitamin K antagonists in these patients has been well established. However, associated bleeding risks may offset the therapeutic benefits in patients with risk factors for bleeding. Despite improvements achieved by novel oral anticoagulants, bleeding remains a clinically relevant problem, especially gastrointestinal bleeding. Percutaneous occlusion of the left atrial appendage (LAA) may be considered as an alternative stroke prevention therapy in AF patients with a high bleeding risk. This paper explores patient groups in whom oral anticoagulation may be challenging and percutaneous LAA occlusion (LAAO) has a potentially better risk–benefit balance. The current status of LAAO and future directions are reviewed, and particular challenges for LAA occlusion requiring further clinical data are discussed. This article is a summary of the Third Global Summit on LAA occlusion, 15 March 2013, Barcelona, Spain.

Description: Aims Whether adjusting interventricular (VV) delay changes haemodynamic efficacy of cardiac resynchronization therapy (CRT) is controversial, with conflicting results. This study addresses whether the convention for keeping atrioventricular (AV) delay constant during VV optimization might explain these conflicts. Method and results Twenty-two patients in sinus rhythm with existing CRT underwent VV optimization using non-invasive systolic blood pressure. Interventricular optimization was performed with four methods for keeping the AV delay constant: (i) atrium and left ventricle delay kept constant, (ii) atrium and right ventricle delay kept constant, (iii) time to the first-activated ventricle kept constant, and (iv) time to the second-activated ventricle kept constant. In 11 patients this was performed with AV delay of 120 ms, and in 11 at AV optimum. At AV 120 ms, time to the first ventricular lead (left or right) was the overwhelming determinant of haemodynamics (13.75 mmHg at ±80 ms, P 〈 0.001) with no significant effect of time to second lead (0.47 mmHg, P = 0.50), P 〈 0.001 for difference. At AV optimum, time to first ventricular lead again had a larger effect (5.03 mmHg, P 〈 0.001) than time to second (2.92 mmHg, P = 0.001), P = 0.02 for difference. Conclusion Time to first ventricular activation is the overwhelming determinant of circulatory function, regardless of whether this is the left or right ventricular lead. If this is kept constant, the effect of changing time to the second ventricle is small or nil, and is not beneficial. In practice, it may be advisable to leave VV delay at zero. Specifying how AV delay is kept fixed might make future VV delay research more enlightening.

Description: Preliminary results are presented from the first validation of geophysical dataproducts (ice concentration, snow thickness on sea ice ( ) and ice temperature ( ) fromthe NASA EOS Aqua AMSR-E sensor, in East Antarctica (in September-October 2003). Thechallenge of collecting sufficient measurements with which to adequately validate thecoarse-resolution AMSR-E data products was addressed by means of a hierarchicalapproach, using detailed in situ measurements, digital aerial photography and other satellitedata. Initial results indicate that, at least under cold conditions with a dry snowcover, thereis a reasonably close agreement between satellite- and aerial photo-derived iceconcentrations i.e., 97.2 ±3.6% for NT2 and 96.5 ±2.5% for BBA algorithms versus 94.3±10% for the aerial photos. In general, the AMSR-E concentration represents a slightoverestimate of the actual concentration, with the largest discrepancies occurring in regionscontaining a relatively high proportion of thin ice. Although the AMSR-E concentrations fromthe NT2 and BBA algorithms are similar on average, differences of 〉5% occur on a point-by-point basis, again related to thin ice distribution. The AMSR-E ice temperature ( ) productagrees with coincident surface measurements to within approximately 0.5o C. Regardingsnow thickness, the AMSR retrieval is a significant underestimate compared to in situmeasurements weighted by the percentage of thin ice (and open water) present. For thecase study analysed, the underestimate was 46% for the overall average, but 23%compared to smooth ice measurements. An encouraging factor is that the spatialdistribution of the AMSR-E product follows an expected and consistent spatial pattern,suggesting that the observed difference may be an offset (at least under freezingconditions). Areas of discrepancy are identified, and the need for future work highlighted.