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High-density three-dimensional (3D) mapping of the pulmonary vein (PV)-left atrial (LA) junction was performed to characterize spontaneous PV activity in humans.The activation patterns of ectopic beats and of the initial 2 seconds of atrial fibrillation (AF) from the PVs were analyzed using a 64-poles basket catheter. A focal mechanism was defined as a discrete site of early and centrifugal activation. Continuous activity was considered as an activation coveringor = 80% of the tachycardia beat-to-beat cycle length within the mapping field. In 35 patients, 123 spontaneous focal ectopic beats that did not induce AF and 95 that did induce AF were mapped. The mean coupling interval of ectopic discharges not inducing AF was 281 +/- 70 msec versus 236 +/- 90 msec for ectopies initiating AF (Por = 0.01). The first ectopic activity of all 218 arrhythmogenic events showed exclusively a focal mechanism. During the 95 episodes of AF initiation, one or two ectopic beats from the PVs initiated AF in the LA in 39%, a stable focal tachycardia was recorded in 14%, continuous activity with important changes in cycle length (35 +/- 15 msec) suggestive of decremental or fibrillatory conduction was found in 18%, and in 29% the activation pattern could not be classified. No stable and sustained reentrant circuit could be identified by our mapping tool in the PV-LA junction.Arrhythmogenic activity from PVs in humans is predominantly due to discrete focal activity.

Abnormal baseline electrocardiograms (ECGs) are common in patients with isolated left ventricular noncompaction (IVNC). Whether certain electrocardiographic parameters are associated with a poor clinical outcome, however, remains elusive. The present study was therefore designed to comprehensively assess the predictive value of baseline ECG findings in patients newly diagnosed with IVNC.74 patients diagnosed with IVNC were included in the analysis. During follow-up, 8 patients (11%) died of a cardiovascular cause or underwent heart transplantation (primary outcome measure). On univariate analysis, several variables, including repolarization abnormalities (ST segment elevation/depression, T-wave inversion) in the inferior leads (5-year estimator: 67.1 ± 10.7% vs. 98 ± 2.2%; P = 0.001), an increase in PQ- (hazard ratio (HR) 1.032, P=0.004) and QTc-duration (HR 1.037, P=0.001), were predictive of cardiovascular death or heart transplantation. On multivariate analysis, only PQ- and QTc-duration and the presence of repolarization abnormalities in the inferior leads remained significantly predictive of a poor outcome.PQ duration, QTc duration, and repolarization abnormalities in the inferior leads are independently predictive of a poor prognosis in IVNC. Further prospective studies are required to conclusively investigate the usefulness of baseline ECG parameters for risk stratification in patients with IVNC.

Chronic right ventricular apical (RVA) pacing has been associated with increased risk of heart failure and adverse outcome. The acute effects of RVA pacing on three-dimensional (3D) ventricular function and mechanical dyssynchrony are not well known. We performed a real-time 3D echocardiographic (RT3DE) study to assess global and regional left ventricular function during RVA pacing.Twenty-six patients with implanted cardiac devices and normal intrinsic atrioventricular conduction were included in the study. RT3DE was performed during intrinsic sinus rhythm and during RVA pacing. Quantification of global and regional left ventricular function was performed offline by time-volume analysis of 16 myocardial segments. Time to reach minimum regional volume was calculated for each segment as a percentage of the cardiac cycle. The systolic dyssynchrony index (SDI) was defined as the standard deviation of these time periods. Longitudinal function was assessed by time-volume analysis of apical, midventricular, and basal segments.During RVA pacing, a reversed apical-to-basal longitudinal contraction sequence was observed in 58% of all patients. RVA pacing was associated with increased left ventricular (LV) dyssynchrony (SDI increase from 4.4 ± 2.2% to 6.3 ± 2.4%, P = 0.001) and reduced LV ejection fraction (decrease from 53 ± 13% to 47 ± 14%, P = 0.05).RT3DE assessment of LV function provides evidence that pacing from the RVA results in acute alterations in LV contraction sequence and increased LV dyssynchrony. Further studies are warranted to assess the potential of RT3DE to identify patients who might be at increased risk of pacing-induced heart failure or who might benefit from alternate-site or multisite pacing.

To assess the effect of intra-arterial magnesium on the radial artery during transradial cardiac catheterization.Transradial coronary angiography has become popular in the last decade and offers several advantages over transfemoral angiography. Radial artery spasm is a major limitation of this approach, and a vasodilatory cocktail is usually given. The aim of this study was to examine the effect of magnesium sulphate on the radial artery during cardiac catheterization.This was a prospective, double-blind, randomized trial of 86 patients undergoing radial catheterization. Patients were randomized to receive magnesium sulphate (150 mg) or verapamil (1 mg) into the radial sheath. Radial dimensions were assessed using Doppler ultrasound. The primary endpoint of the study was a change in radial artery diameter following administration. Secondary endpoints included operator-defined radial artery spasm and patient pain.Following administration of the study drug, there was an increase in radial artery diameter in both groups (p0.01), although the increase seen was greater in the group receiving magnesium (magnesium 0.36 +/- 0.03 mm; verapamil 0.27 +/- 0.03 mm; p0.05). Administration of verapamil resulted in a fall in mean arterial pressure (MAP) (change in MAP -6.6 +/- 1.4 mmHg; p0.01), whereas magnesium did not have a hemodynamic effect. Severe arm pain (pain score5) was observed in 14 (30%) patients receiving verapamil and 9 (27%) receiving magnesium (p = NS).This study demonstrates that magnesium is a more effective vasodilator when compared to verapamil, with a reduced hemodynamic effect, and is equally effective at preventing radial artery spasm. As such, the use of this agent offers distinct advantages over verapamil during radial catheterization.