A left lateral body position increases pulmonary vein stress in healthy humans.

Pulmonary vein (PV) stretch is proarrhythmic for atrial fibrillation (AF). AF patients often report that a left lateral (LL) body position can trigger arrhythmia symptoms. Because the PV myocardium is thought to trigger AF, we hypothesized that the LL compared to the supine body position increases PV wall stress. Functional cardiac magnetic resonance imaging was performed in supine and LL recumbent body position in awake condition in healthy human volunteers (n = 20). Following a change from supine to LL position, the heart moved in an anterior-LL direction in the thorax. The right superior PV diameter was increased by 19% (24.6 ± 3.1 vs. 20.7 ± 3.2 mm, p = 0.009) and left atrial (LA) volume was larger by 17% (61.7[15.4] vs. 51.0[17.8] ml, p = 0.015) in LL than supine position, respectively. The passive LA conduit fraction (normalized difference between maximum and pre-contraction LA volume) increased by 25% in LL compared to supine position (19.6 ± 9.0 vs. 15.7 ± 7.6%, respectively, p = 0.016). Local wall stress in the PV regions increased in LL compared to supine position (overall mean: 1.01 ± 0.12 vs. 1.10 ± 0.10 arb. unit, LL vs. supine, position effect p = 0.041), whereas this was not the case in the LA walls (overall mean: 1.18 ± 0.31 vs. 1.21 ± 0.21 arb. unit, LL vs. supine, position effect p = 0.381). In conclusion, a left lateral body position increases PV myocardial stress during the atrial relaxation phase of healthy volunteers. These results have implications for the mechanisms of posture-triggered AF.

Continuous Cardiac Monitoring around Atrial Fibrillation Ablation: Insights on Clinical Classifications and End Points.

BACKGROUND: Atrial fibrillation (AF) is an arrhythmia that can be difficult to identify and classify with short-term monitoring. However, current standard of practice requires only short-term monitoring to determine AF classifications and identify symptom-arrhythmia correlations prior to AF ablation procedures. Insertable cardiac monitors (ICMs) offer continuous arrhythmia monitoring, which could lead to a more accurate measurement of AF burden than standard of practice. METHODS: This analysis focused on 121 patients enrolled in the LINQ Usability Study indicated for an AF ablation. Patients were followed for up to 1 year after ICM insertion. Clinical AF classifications were made by physicians prior to ICM implantation based on available clinical information. Device-detected AF burden and maximum daily burden were collected from device interrogations and remote transmissions. Device AF classifications were determined by categorizing the AF burden based on guidelines. RESULTS: Agreement between clinical and device AF classifications preablation was poor (48.3%, N = 58). The strongest agreement was in the paroxysmal AF group but still was only 61.8%. Furthermore, device-detected preablation AF burden led to the decision to defer AF ablation procedures in 16 (13.2%) patients. The median AF burden in patients with ≥6 months follow-up postablation (n = 71) was reduced from 7.8% (interquartile range [IQR]: 0-32.1%) to 0% (IQR: 0-0.7%). CONCLUSIONS: ICM monitoring to determine AF burden pre- and post-AF ablation may have clinical utility for management of ablation candidates through more accurate AF classification and guiding treatment decisions.

Observations and Considerations on Patient X-ray Exposure in the Electrophysiology Lab.

To assess patient radiation during catheter ablation procedures and operator differences. From 84 patients (51 males, age 63 ± 10 years) undergoing complex catheter ablation by three experienced operators we collected: body mass index (BMI), procedure type and time, fluoroscopy time, dose area product (DAP), air kerma and X-ray system setting (cine, collimation and angiographic imaging angle). A new factor, fluoroscopy DAP-fluoroscopy time ratio, was introduced to compare operator differences. The results show the average procedure time was 179 (± 57) minutes (min), fluoroscopy time was 31 (± 21) min, DAP was 26.4 (± 19.6) Gy.cm(2) and air kerma was 0.26 (± 0.19) Gy. Procedure types were: pulmonary vein isolation (PVI) (52 %), redo PVI (11 %), pulmonary vein ablation catheter (PVAC) (14 %), ventricular tachycardia (VT) (8 %) and others (15 %). Inter-operator difference was observed in fluoroscopy and cine usage. Fluoroscopy DAP-time ratios showed a similar level of patient radiation dose rate by operator A and B (correlation: 0.89), and a significantly higher dose rate by operator C (correlation: 0.20, p<0.001; 0.26, p<0.01, to operator A and B). In conclusion, operators should be aware of patient radiation exposure levels and the influencing factors. Inter- and intra-operator differences can be measured and bench marked for improvement in X-ray efficiency and patient radiation reduction.