Impacto da Estimulação Vagal na Indução e Interrupção de Fibrilhação Auricular no Modelo do Coração de Coelho in Vivo

INTRODUCTION: Vagal activity is thought to influence atrial electrophysiological properties and play a role in the initiation and maintenance of atrial fibrillation (AF). In this study, we assessed the effects of acute vagal stimulation (vagus_stim) on atrial conduction times, atrial and pulmonary vein (PV) refractoriness, and vulnerability to induction of AF in the rabbit heart with intact autonomic innervation. METHODS: An open-chest epicardial approach was performed in 11 rabbits (New Zealand; 3.9-5.0 kg), anesthetized and artificially ventilated after neuromuscular blockade. A 3-lead ECG was obtained. Atrial electrograms were recorded along the atria, from right to left (four monopolar electrodes), together with a circular electrode adapted for proximal left PV assessment. Acute vagus nerve stimulation was obtained with bipolar electrodes (20 Hz). Epicardial activation was recorded in sinus rhythm, and the conduction time from right (RA) to left atrium (LA), and from RA to PVs, was measured in basal conditions and during vagus_stim. The atrial effective refractory period (ERP) and dispersion of refractoriness (Disp_A) were analyzed. Vulnerability to AF induction was assessed at the right (RAA) and left (LAA) atrial appendages and the PVs. Atrial stimulation (50 Hz) was performed alone or combined with vagus_stim. Heart rate and blood pressure were monitored. RESULTS: In basal conditions, there was a significant delay in conduction from RA to PVs, not influenced by vagus_stim, and the PV ERPs were shorter than those measured in LA and LAA, but without significant differences compared to RA and RAA. During vagus_stim, conduction times between RA and LA increased from 16+8 ms to 27+6 ms (p < 0.05) and ERPs shortened significantly in RA, LAA and LA (p < 0.05), but not in RAA. There were no significant differences in Disp_A. AF induction was reproducible in 45% of cases at 50 Hz and in 100% at 50 Hz+vagus_stim (p < 0.05). The duration of inducible AF increased from 1.0 +/- 0.2 s to 12.0 +/- 4.5 s with 50 Hz+vagus_stim (p < 0.01). AF lasted >10 s in 45.4% of rabbits during vagus_stim, and ceased after vagus_stim in 4 out of these 5 cases. In 3 animals, PV tachycardia, with fibrillatory conduction, induced with 50 Hz PV pacing during vagus_stim. CONCLUSIONS: Vagus_stim reduces interatrial conduction velocity and significantly shortens atrial ERP, contributing to the induction and duration of AF episodes in the in vivo rabbit heart. This model may be useful for the assessment of autonomic influence on the pathophysiology of AF.

Phototherapy in Childhood: a 17-Year Retrospective Study Regarding Effectiveness and Safety

Introduction: Skin diseases in paediatric age are often distressing conditions with significant impact in children’s psychosocial development. Additionally, systemic therapeutic options are often limited in childhood, due to its potential toxicity in this vulnerable group. Phototherapy is therefore an endorsed option for photo-responsive dermatological conditions. Objective and Methods:This observational retrospective study aims to access efficacy and safety of Phototherapy in our paediatric population. Relevant clinical data from 1996 to present concerning patients aged 18 years or less was collected. Results: 78 patients were included, of which64,1%was female. Mean age was 12,9 years (range 2-18). Distribution according to diagnosis was:47,4%psoriasis, 34,6% alopecia areata, 9,0% vitiligo, 9,0% other diagnosis. Mean number of cycles was 1,5 (range 1-7), with an average of 16,3 treatments per cycle and mean cumulative dose 134 J/cm2. 70,5% was treated with one single cycle. Topic and systemic PUVA were the first choice in 37,2% and 39,7%, respectively, while UVB TL01 and broadband UVB were used in 11,5% each. On the first cycle 67,5% improved, 14,3% showed no sustained clinical response and 19,5% were lost to follow-up. Psoriasis patients had the best response rates (81,8%), followed by alopecia areata (59,3%). Side effects occurred in 21%, being erythema the most common (12%). None led to therapeutic interruption. Discussion: Phototherapy is a safe and effective option in childhood, yet the withdraw rate might be an important limitation.

Alcohol Septal Ablation in Obstructive Hypertrophic Cardiomyopathy: Four Years of Experience at a Reference Center

INTRODUCTION: We describe our center's initial experience with alcohol septal ablation (ASA) for the treatment of obstructive hypertrophic cardiomyopathy. The procedure, its indications, results and clinical outcomes will be addressed, as will its current position compared to surgical myectomy. OBJECTIVE: To assess the results of ASA in all patients treated in the first four years of activity at our center. METHODS: We retrospectively studied all consecutive and unselected patients treated by ASA between January 2009 and February 2013. RESULTS: In the first four years of experience 40 patients were treated in our center. In three patients (7.5%) the intervention was repeated. Procedural success was 84%. Minor complications occurred in 7.5%. Two patients received a permanent pacemaker for atrioventricular block (6% of those without previous pacemaker). The major complication rate was 5%. There were no in-hospital deaths; during clinical follow-up (22 ± 14 months) cardiovascular mortality was 2.5% and overall mortality was 5%. DISCUSSION AND CONCLUSION: The results presented reflect the initial experience of our center with ASA. The success rate was high and in line with published results, but with room to improve with better patient selection. ASA was shown to be safe, with a low complication rate and no procedure-related mortality. Our experience confirms ASA as a percutaneous alternative to myectomy for the treatment of symptomatic patients with obstructive hypertrophic cardiomyopathy refractory to medical treatment.

Femoral Approach: an Exceptional Alternative for Permanent Pacemaker Implantation

The classic transvenous implantation of a permanent pacemaker in a pectoral location may be precluded by obstruction of venous access through the superior vena cava or recent infection at the implant site. When these barriers to the procedure are bilateral and there are also contraindications or technical difficulties to performing a thoracotomy for an epicardial approach, the femoral vein, although rarely used, can be a viable alternative. We describe the case of a patient with occlusion of both subclavian veins and a high risk for mini-thoracotomy or videothoracoscopy, who underwent implantation of a permanent single-chamber pacemaker via the right femoral vein.