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.

Accelerated idioventricular rhythm requiring catheter ablation in a child: The dark side of a benign arrhythmia.

A 12 year-old boy, with no history of cardiac disease, was referred to our department for evaluation of an incessant accelerated idioventricular rhythm (AIVR) complicated with severe left ventricular (LV) dysfunction and cardiogenic shock. Extensive diagnostic work-up failed to reveal any structural heart disease. During electrophysiological study, AIVR originated from the right ventricular endocardial anterior wall and was successfully ablated using remote magnetic navigation. LV function showed complete recovery four weeks after the procedure. This case highlights a life-threatening evolution of an arrhythmia generally presented as a benign entity in children.

[The use of transesophageal echocardiography to guide the trans-septal puncture. Practical guide, tips and tricks]. / Échocardiographie transœsophagienne pour guider la ponction transseptale. Guide pratique, astuces, particularités, pièges.

Transesophageal echocardiography is very useful to guide transseptal puncture for left atrial ablation procedures. This paper is a practical guide for the ultrasonographer who seeks to meet the expectations of the electrophysiologist, but also for young EP's in order to improve their understanding of the echocardiographical views and to ameliorate the communication between the two specialists. The tips and tricks of all the steps of the exam are presented.

[Usefulness of tricuspid annular displacement (TAD) to identify right ventricular dysfunction in normotensive patients with acute pulmonary embolism]. / Intérêt du tricuspid annular displacement (TAD) dans l'évaluation de la dysfonction ventriculaire droite au cours de l'embolie pulmonaire.

BACKGROUND: Echocardiographic criteria of right ventricular dysfunction (RVD) in acute pulmonary embolism (PE) differ among published studies. Assessment of RV systolic function remains difficult because of the RV's complex shape. We aimed to evaluate RV systolic function with TAD in patients (pts) with acute PE. TAD (QLAB, Philips Medical Imaging) was based on a tissue-tracking algorithm that is ultrasound beam angle independent for automated detection of tricuspid annular displacement. DESIGN: Prospective and observational study. METHODS: All adults' pts who were diagnosed with PE from December 2008 to December 2009 at Princess Grace Hospital, Monaco were eligible for this study after exclusion of history of heart failure. We evaluated 36 consecutive pts with PE (18 male, mean age 62.7 years), which underwent echocardiography, plasma BNP titration during the first day after admission, and a second echocardiography obtained within 48 hours before discharge. RESULTS: TAD value were significantly lower in pts with abnormal RV function by echocardiogram (15.9 ± 0.3 vs. 12.7 ± 0.2 ; P = 0.026). Pts with a normal BNP (<80 pg/ml) had an elevated TAD (16.4 ± 0.2 vs. 11.2 ± 0.3 mm ; P < 0.0001). At discharge, echocardiographic data were obtained from 33 pts (mean: 8.3 ± 3.5 days). RV end diastolic diameter, RV to LV diameter, pulmonary arterial systolic pressure, mean pulmonic valve acceleration time, RV FAC, Sa and TAD were significantly improved. There was no difference between TAD among pts with echocardiographic RVD at baseline vs. pts without RVD (14.9 ± 3.7 vs. 16.1 ± 2.9 mm ; P = 0.3). Four pts who deteriorated during short-term observation had substantially lower TAD values than those with uncomplicated courses (7.7 ± 0.4mm vs. 14.6 ± 0.2 mm ; P = 0.001). In conclusion, impaired TAD was associated with decreased RV systolic function in pts with acute PE. To identify the clinical meaning of decreased TAD, larger trials with longer follow-up periods are needed.

[Arrhythmia follow-up of children and adolescents with neuromuscular diseases]. / Surveillance rythmologique de l'enfant et l'adolescent avec maladie neuro-musculaire.

Much progress has been made over the last few years in understanding and classifying neuromuscular diseases. The heart is frequently affected but often in a dissociated manner with respect to the neuromuscular signs although it has a significant impact on the prognosis. In children and adolescents, the dystrophinopathies, especially Duchenne's muscular dystrophy, are the principal problems but the mild arrhythmic events observed seem to be related to left ventricular dysfunction. On the other hand, in myotonic dystrophies (Steinert's disease), ventricular arrhythmias or conduction defects may appear at an early stage of the disease with serious consequences justifying appropriate follow-up and invasive preventive measures. Emery Dreifuss X-linked dystrophy and other laminopathies are rare conditions but are associated with sudden death and cardiomyopathies of the young adult. Specialised cardiological follow-up is justified in childhood from the time of diagnosis. Medication or implantable electric devices may be justified before the end of the second decade of life. Progressive infra-hisian conduction defects have also been reported in Kearns-Sayre oculo-pharyngeal myopathy. Prospective studies are required at this age to determine the natural history of these pathologies that are probably under diagnosed. The present recommendations, which are based mainly on data from adult series, could then be adapted for younger patients.