A new experimentally validated formula to calculate the QT interval in the presence of left bundle branch block holds true in the clinical setting.

BACKGROUND: The evaluation of the QT interval in the presence of left bundle branch block (LBBB) is associated with the challenge to discriminate native QT interval from the prolongation due to the increase in QRS duration. The newest formula to evaluate QT interval in the presence of LBBB suggests: modified QT during LBBB = measured QT interval minus 50% of LBBB duration. The purpose of this study is therefore to validate the abovementioned formula in the clinical setting. METHODS: Validation in two separate groups of patients: Patients who alternated between narrow QRS and intermittent LBBB and patients with narrow QRS who developed LBBB after transcatheter aortic valve implantation (TAVI). RESULTS: The acquired mean native QTc intervals and those calculated by the presented formula displayed no significant differences (p > .99 and p > .75). CONCLUSIONS: In this study we proved for the first time the validity and applicability of the experimentally acquired formula for the evaluation of the QT interval in the presence of LBBB in a clinical setting.

First results and follow-up of a second-generation circular mapping and ablation catheter.

PURPOSE: Pulmonary vein isolation with radiofrequency energy is widely used as a strategy for catheter ablation of atrial fibrillation (AF). Anatomically designed catheters have been developed to increase the efficiency of AF ablation procedures. The second-generation circular ablation catheter, PVAC GOLD, was re-designed to improve energy delivery and mitigate emboli. We investigated the procedural efficiency, biophysics, and chronic efficacy of PVAC GOLD in patients with AF. METHODS: We consecutively enrolled 40 patients (60 ± 11 years) with highly symptomatic, drug refractory AF. The first 20 patients were treated with the first-generation PVAC. The subsequent 20 patients were treated with the second-generation PVAC GOLD catheter. All patients were followed up at 3, 6, and 12 months. RESULTS: All 164 targeted PVs were successfully isolated. Ablations performed with PVAC GOLD showed a significant reduction in total number of ablations needed for PVI, fluoroscopy, and procedure times compared to PVAC (34.7 ± 7.0 vs. 27.0 ± 6.5; p = 0.009), fluoroscopy (29.5 ± 9.5 vs. 23.4 ± 7.0; p = 0.026), and procedure time (93.8 ± 18.9 vs. 83.1 ± 10.6; p = 0.033). PVAC GOLD showed improved biophysics including a reduction of low power ablations and an increase in mean effective energy delivery. At 12 months follow-up, AF recurrence rates were comparable in the two groups (35 vs. 30 %; p = 0.735). There were no adverse events. CONCLUSIONS: The redesigned PVAC GOLD catheter demonstrates a reduction in radiofrequency ablation and procedure time and improved biophysics while maintaining chronic efficacy compared to the first-generation PVAC.

Comparison of cardiogoniometry and ECG at rest versus myocardial perfusion scintigraphy.

BACKGROUND: Cardiogoniometry (CGM) is a novel resting electrocardiac method based on computer-generated three-dimensional data derived from cardiac potentials. The purpose of this study was to determine CGM's and electrocardiography's (ECG) accuracy for detecting myocardial ischemia and/or lesions in comparison with stress/rest myocardial perfusion scintigraphy (single photon emission computer tomography [SPECT]). METHOD: A cohort of consecutively enrolled patients (n = 100) with suspected or known coronary artery disease (mean age 67.8 years, 52% female) were examined by CGM and resting ECG before stress/rest myocardial scintigraphy. RESULTS: Pathological scintigraphy findings at adenosine stress perfusion (ASP) and/or rest were conclusively identified in 21 patients. Diagnostic sensitivity was 71% for CGM and 24% for ECG, specificity was 70% for CGM and 95% for ECG. Reversible ischemia was diagnosed in 16 of 21 patients with pathological scintigraphy results. In this subgroup, sensitivity was 67% for CGM and 25% for ECG. CONCLUSIONS: At rest, the sensitivity of a CGM significantly surmounts that of a standard 12-lead ECG for detection of isolated myocardial ischemia or myocardial lesions revealed by scintigraphy/SPECT; specificity is in a reasonable range. CGM's ease of use and its considerable agreement with the results of myocardial scintigraphy, suggests a possible role for patient screening in the primary care setting.

Fast routing in road networks with transit nodes.

When you drive to somewhere far away, you will leave your current location via one of only a few important traffic junctions. Starting from this informal observation, we developed an algorithmic approach, transit node routing, that allows us to reduce quickest path queries in road networks to a small number of table lookups. For road maps of Western Europe and the United States, our best query times improved over the best previously published figures by two orders of magnitude. This is also more than one million times faster than the best known algorithm for general networks.