Sérgio Laranjo

Wavelet analysis of autonomic outflow of normal subjects on head‐up tilt, cold pressor test, Valsalva manoeuvre and deep breathing

Non‐invasive autonomic evaluation has used fast Fourier transform (FFT) to assign a range of low (LF) and high frequencies (HF) as markers of sympathetic and parasympathetic influences, respectively. However, FFT cannot be applied to brief transient phenomena, such as those observed on performing autonomic tests where the acute changes of cardiovascular signals (blood pressure and heart rate) that represent the first and most important stage of the autonomic performance towards a new state of equilibrium occur. Wavelet analysis has been proposed as a method to overcome and complement information taken exclusively in the frequency domain. With discrete wavelet transform (DWT), a time–frequency analysis can be done, allowing the visualization in time of the contribution of LF and HF to the observed changes of a particular signal. In this study, we evaluate with wavelets the acute changes in R–R intervals and systolic blood pressure that are observed in normal subjects during four classical autonomic tests: head‐up tilt (HUT), cold pressor test (CPT), deep breathing (DB) and Valsalva manoeuvre (VM). Continuous monitoring of ECG and blood presure was performed. Also LF, HF and LF/HF were calculated. Consistent with previous interpretations, data showed an increase of sympathetic activity in HUT, CPT and VM. On DB, results reflected an increase in parasympathetic activity and frequencies. In conclusion, when compared with FFT, wavelet analysis allows the evaluation of autonomic variability during short and non‐stationary periods of time and may constitute a useful advance in the assessment of autonomic function in both physiological and pathological conditions.

Postictal generalized EEG suppression is not associated with periictal cardiac autonomic instability in people with convulsive seizures

Purpose:  Postictal generalized EEG suppression (PGES) seems to be a pathophysiologic hallmark in ictal recordings of sudden unexpected death in epilepsy (SUDEP). It has recently been suggested that presence and duration of PGES might be a predictor of SUDEP risk. Little is known about the etiology of PGES.

Acute vagal modulation of electrophysiology of the atrial and pulmonary veins increases vulnerability to atrial fibrillation

Vagal activity is thought to influence atrial electrophysiological properties and play a role in the initiation and maintenance of atrial fibrillation (AF). We evaluated the effects of acute vagal stimulation on atrial conduction, refractoriness of atrial and pulmonary veins (PVs) and inducibility of AF. An open‐chest epicardial approach was performed in New Zealand White rabbits with preserved autonomic innervation. Atrial electrograms were obtained with four unipolar electrodes placed epicardially along the atria (n= 22) and an electrode adapted to the proximal left PV (n= 10). The cervical vagus nerve was stimulated with bipolar platinum electrodes (20 Hz). Epicardial activation was recorded in sinus rhythm, and effective refractory periods (ERPs), dispersion of refractoriness and conduction times from high‐lateral right atrium (RA) to high‐lateral left atrium (LA) and PVs assessed at baseline and during vagal stimulation. Burst pacing (50 Hz, 10 s), alone or combined with vagal stimulation, was applied to the right (RAA) and left atrial appendage (LAA) and PVs to induce AF. At baseline, ERPs were lower in PVs than in LA and LAA, but did not differ significantly from RA and RAA, and there was a significant delay in the conduction time from RA to PVs compared with the activation time from RA to LA (P < 0.01). During vagal stimulation, ERP decreased significantly at all sites, without significant differences in the dispersion of refractoriness, and the atrial conduction times changed from 39 ± 19 to 49 ± 9 ms (RA to PVs; n.s.) and from 14 ± 7 to 28 ± 12 ms (RA to LA; P= 0.01). Induction of AF was reproducible in 50% of cases with 50 Hz and in 82% with 50 Hz combined with vagal stimulation (P < 0.05). During vagal stimulation, AF cycle length decreased at all sites, and AF duration changed from 1.0 ± 0.9 to 14.0 ± 10.0 s (P < 0.01), with documentation of PV tachycardia in three cases. In 70% of the animals, AF ceased immediately after interruption of vagal stimulation. We conclude that in the intact rabbit heart, vagal activity prolongs interatrial conduction and shortens atrial and PV ERP, contributing to the vulnerability to the induction and maintenance of AF. This model may be useful in the assessment of the autonomic influence in the mechanisms underlying AF.

The Role of Propranolol in the Treatment of Infantile Hemangioma

INTRODUCTION Infantile hemangioma (IH) is one of the most common childhood tumors. There are various medical or surgical therapeutic options, all with suboptimal results. Recently, the successful use of propranolol for involution of IH was described. We report the results of a single-center experience with this therapeutic option. OBJECTIVE To prospectively assess the efficacy and safety of propranolol in children with infantile hemangioma. METHODS We performed a prospective analysis of clinical data of all patients with IH referred to a pediatric cardiology center for baseline cardiovascular assessment prior to propranolol therapy. Propranolol was given at a starting dose of 1 mg/kg/day and titrated to a target dose of 2-3 mg/kg/day according to clinical response. Efficacy was assessed through a photograph-based severity scoring scale. Safety was assessed by collecting data regarding significant side effects. RESULTS Starting in 2010, 30 patients (15 female) were referred for propranolol treatment of IH, at a median age of six months (1-63 months). The mean target propranolol dose was 2.8 mg/kg/day, with a mean duration of therapy of 12 months. All patients experienced significant reduction of IH size and volume. There were no side effects. CONCLUSIONS In our experience propranolol appears to be a useful and safe treatment option for severe or complicated IH, achieving a rapid and significant reduction in their size. No adverse effects were observed, although until larger clinical trials are completed, potential adverse events should be borne in mind and consultation with local specialists is recommended prior to initiating treatment.

An insight into the autonomic and haemodynamic mechanisms underlying reflex syncope in children and adolescents: a multiparametric analysis.

Around 15% of children and adolescents experience at least one episode of syncope until adulthood. Excluding cardiac disease, the majority of syncopes are of reflex origin and benign in nature. In this situation, a tilt test is conducted to reproduce symptoms and to evaluate cardiovascular adaptations to orthostatism, but its mechanisms are not yet well defined. Here, we investigated haemodynamics and autonomic activity during tilt in young patients. Patients (n=113) with unexplained syncope were enrolled. Tilt followed a standard protocol without provocative agents. A positive response (fainters) was defined as a sudden development of syncope or presyncope associated with hypotension, bradycardia, or both. Haemodynamic parameters, autonomic activity, and baroreflex sensibility were evaluated. Data were analysed on baseline; immediately after tilting; on tilt adaptation; before fainting or before tilt-down for non-fainters; and on tilt-down. A total of 45 patients experienced syncope after a mean time of 18 minutes. During tilting up, fainters showed lower blood pressure and peripheral resistance values, which decreased progressively with time together with baroreflex sensibility. Sympathetic tone increased massively along time till syncope. No changes in cardiac output and heart rate were observed. Results show a strong effort of the autonomic nervous system to adapt to orthostatic stress through different magnitudes of sympathetic output, which was maximal before syncope without apparent modifications of parasympathetic tone. These changes suggest an imbalance between both branches of the autonomic nervous system, not enabling a time-progressive adaptation and leading the subject to faint.

Twelve Years of Kawasaki Disease in Portugal: Epidemiology in Hospitalized Children

Background: Kawasaki disease (KD) is the leading cause of acquired heart disease in developed countries. Reported incidences vary worldwide but incidence of KD has not been established in Portugal. Aim: The aims of the study were to describe the epidemiologic characteristics and estimate incidence rates of KD among hospitalized children in Portugal. Methods: This study was a descriptive, population-based study, which used hospital discharge records of patients <20 years of age diagnosed with KD from the Hospital Register database for 2000–2011. Incidence rates were calculated using the number of KD patients and corresponding National census data. Results: There were 533 hospitalizations of 470 patients with KD as the primary diagnosis in Portugal, 63 hospitalizations were transfers of patients between hospitals and there were no relapses. The mean age at admission was 2.8 years, with male predominance (male-to-female ratio: 1.6:1). Children <5 years and infants <1 year represented 83% and 23% of all the patients admitted, respectively. Mean annual incidence was 6.5 per 100,000 children <5 years, 4.5 per 100,000 infants <1 year and 7.8 per 100,000 infants 1–4 years. We found considerable differences between national territorial regions, with majority of cases in most dense regions. The mean length of hospital stay was 9 days, and the incidence peaked in spring (35%) and spring/winter (63%). Coronary aneurysms were reported in 8.5% of patients with a higher male-to-female ratio (3.4:1) and a lower mean age (1.93 years). Reported mortality was 0.4%. Conclusions: This is the first large-scale epidemiologic study of KD in Portugal. The highest incidences occurred among male children 1–4 years of age and in spring/winter.

Successful catheter ablation of a left anterior accessory pathway from the non-coronary cusp of the aortic valve.

Left anterior accessory pathways are considered to be rare findings. Catheter ablation of accessory pathways in this location remains a challenging target, and few reports about successful ablation of these accessory pathways are available. We describe our experience regarding a case of a manifest left anterior accessory pathway ablation using radiofrequency energy at the junction of the left coronary cusp with the non-coronary cusp.

The hybrid approach for palliation of hypoplastic left heart syndrome: Intermediate results of a single-center experience

INTRODUCTION Hypoplastic left heart syndrome (HLHS) is a major cause of cardiac death during the first week of life. The hybrid approach is a reliable, reproducible treatment option for patients with HLHS. Herein we report our results using this approach, focusing on its efficacy, safety and late outcome. METHODS We reviewed prospectively collected data on patients treated for HLHS using a hybrid approach between July 2007 and September 2014. RESULTS Nine patients had a stage 1 hybrid procedure, with seven undergoing a comprehensive stage 2 procedure. One patient completed the Fontan procedure. Five patients underwent balloon atrial septostomy after the hybrid procedure; in three patients, a stent was placed across the atrial septum. There were three deaths: two early after the hybrid procedure and one early after stage two palliation. Overall survival was 66%. CONCLUSIONS In our single-center series, the hybrid approach for HLHS yields intermediate results comparable to those of the Norwood strategy. The existence of dedicated teams for the diagnosis and management of these patients, preferably in high-volume centers, is of major importance in this condition.

Dual etiology of dilated cardiomyopathy: The synergistic role of vitamin D deficiency

Dilated cardiomyopathy is the commonest form of cardiomyopathy in pediatric patients. Various causal factors have been identified, including ionic imbalance. Calcium ions play an essential role in regulating myocardial contractile function, and the harmful role of hypocalcemia as a coadjuvant or even precipitating factor of worsening heart failure has been described in rare case reports. Multiple causative factors may occasionally be present. We describe the first case, to our knowledge, of dilated cardiomyopathy in an infant with severe hypocalcemia and viral myocarditis.

Autonomic modulation in a patient with syncope and paroxysmal atrial-fibrillation

We report a case of a patient with recurrent syncope and paroxysmal atrial fibrillation whose clinical status greatly improved after a period of orthostatic training. The potential efficacy of this non-pharmacological measure in modulating the autonomic tone is discussed below.