Respiratory variability of sinus node activation in humans: insights from ultra-high-density mapping.

PURPOSE: Experimental data suggest that shifts in the site of origin of the sinus node (SN) correlate with changes in heart rate and P wave morphology. The direct visualization of the effect of respiration on SN electrical activation has not yet been reported in humans. We aimed to measure the respiratory shifting of the SN activation using ultra-high-density mapping. METHODS: Sequential right atrial (RA) activation mapping during sinus rhythm (SR) was performed. Three maps were acquired for each patient: basal end-expiratory (Ex), end-inspiratory (Ins), and end-expiratory under isoproterenol (Iso). The earliest activation site (EAS) was defined as the earliest unipolar electrograms (EGM) with a QS pattern and was localized with respect to the ostium of the superior vena cava (SVC; negative values if EAS inside the SVC). RESULTS: In 20 patients, 49 maps in SR were acquired (20 Ex, 19 Ins, and 10 Iso). Expiratory (944 ± 227 ms) and inspiratory (946 ± 227 ms) SR cycle lengths were similar, but shortened under isoproterenol (752 ± 302 ms). Activation was unicentric in 33 maps and multicentric in 16: 4 during Ins, 10 during Ex, and 2 Iso. EAS location was significantly more cranial in expiration than in inspiration (0.27 ± 12.1 vs 5 ± 11.51 mm, p = 0.01). Iso infusion tends to induce a supplemental cranial shift (-4.07 ± 15.83 vs 0.27 ± 12.7 mm, p = 0.21). EAS were found in SVC in 22.7% of maps (30% Ex, 21% Ins, and 8% Iso). CONCLUSION: Inspiration induces a significant caudal shift of the earliest sinus activation. In one-third of the cases, sinus rhythm earliest activation is inside the SVC.

[Organization and management of acute complete atrioventricular block: Results from a Multicenter National Survey]. / Organisation et gestion aiguë du bloc atrioventriculaire complet : résultats d'une enquête multicentrique nationale.

BACKGROUND: Complete atrioventricular block (AVB3) may be an urgent potentially lifethreatening situation. Our objective was to describe the routine management of AVB 3, with emphasis on the organizational aspects. METHODS: From September 2019 to November 2019, a prospective national survey including 28 questions was electronically sent to 100 physicians (Google Form). RESULTS: The answers were collected from 93 physicians (response rate 93%). Permanent pacemaker implantation during weekends and nights (after 8PM) is possible for 49% of the operators (<5 times a year), for 15% (>5 times a year), impossible for 36% of the operators. For AVB3 nonresponsive to isoproterenol occurring during the night, a temporary pacing lead (TPL) is implanted by: the on-site medical staff on-duty (27%), the on-call interventional cardiologist (21%), the on-call electrophysiologist (19%), a permanent pacemaker is implanted by the electrophysiologist (12%), the strategy is not standardized (15%). An externalized active fixation lead (AFL) for AVB3 has already been implanted by 50% of the operators. 80 (86%) have already observed a dislocation of the TPL, a cardiac perforation already occurred in 57 (61%), a groin hematoma in 35 (38%), and this technique was proscribed for 4% of the operators. CONCLUSION: Our survey shows important disparities in terms of management of AVB3 among the different centers. An externalized AFL with a reusable generator was used by half of the centers.