Stefano Strano

Management of syncope: clinical and economic impact of a Syncope Unit

AIMS Aim of this observational study is to evaluate the clinical performance of a Syncope Unit, in order to assess whether the implemented organization really improves syncope management. METHODS AND RESULTS The study enrolled patients with unexplained syncope who were consecutively referred to our Syncope Unit, either as outpatients or during hospitalization, in a 2-month period. The design of this observational study consists in three phases: a retrospective analysis of their clinical management in the 9 months prior to the first attendance at the Syncope Unit (phase one), their subsequent clinical management in the Syncope Unit (phase two) and a 9-month follow-up (phase three). The retrospective analysis of phase one showed that 25% of patients had already been hospitalized without diagnosis. After Syncope Unit evaluation, diagnosis was obtained in 82% of patients, with 15% of patients indicated to pacing. In the follow-up, 23% of patients experienced a syncopal recurrence. Our analysis indicated an 85% reduction of hospital costs in the follow-up period. CONCLUSION The clinical and economic analysis of the three phases of our study demonstrates that a Syncope Unit allows an improved management of patients with syncope.

Power spectrum analysis contribution to the detection of cardiovascular dysautonomia in multiple sclerosis

In multiple sclerosis (MS) autonomic cardiovascular dysfunction is an uncommon, but potentially dangerous event, to which studies of spectral analysis of heart rate variability have not been applied, yet. Material and methods – We studied 16 patients with definite MS (11 women and 5 men, mean age 30.3 ± 7.4 yrs., mean EDSS 2.06±1.42) and 16 sex‐ and age‐matched healthy controls. Besides cardiovascular reflex tests (valsalva manoeuvre, deep breathing, lying to standing, Blood Pressure response to standing and sustained handgrip), each underwent spectral analysis of the R‐R interval short‐term variability at rest and after tilting, to detect three components: very low frequency (VLF), low frequency (LF) and high frequency (HF). A recent brain MRI was obtained from patients, to compare plaque characteristics with spectral parameters. Results – At cardiovascular reflexes, only four patients (25%) showed an impairment, mostly of a mild degree. VLF and LF at rest were lower in MS subjects than in controls (p<0.01). No significant correlation was found between spectral parameters and lesion area or localization as detected on MRI. Conclusions – Spectral analysis could usefully flank reflex tests to detect autonomic subclinical cardiovascular abnormalities.

The potential prognostic role of cardiovascular autonomic failure in α-synucleinopathies

Cardiovascular autonomic failure is the second most common dysautonomic feature of α‐synucleinopathies and has significant impact on daily activities and quality of life. Here we provide a systematic review of cardiovascular autonomic failure in α‐synucleinopathies, emphasizing its impact on cognitive functions and disease outcomes. Articles spanning the period between January 1985 and April 2012 were identified from the PubMed database using a keyword‐based search. Epidemiological studies highlight the negative prognostic effect of cardiovascular autonomic failure on cardiovascular and cerebrovascular outcomes and overall mortality in all α‐synucleinopathies. Altered cerebral perfusion, vascular pressure stress, and related disruption of the blood–brain barrier may also contribute to the white matter hyperintensities and cognitive dysfunction frequently found in patients affected by neurocardiovascular instability. These findings support the hypothesis that cardiovascular autonomic failure may play a negative prognostic role in α‐synucleinopathies and suggest that precocious screening and therapeutic management of cardiovascular autonomic failure may positively impact disease course.

RESPIRATORY SINUS ARRHYTHMIA AND CARDIOVASCULAR NEURAL REGULATION IN ATHLETES

ABSTRACTStudies using spectral analysis of cardiovascular variability as a noninvasive means for assessing autonomic nervous system activity have provided controversial results in athletes. One reason is that a slow breathing rate-a common feature in athletes-affects spectral estimation because it c

Sympathetic-Parasympathetic Activation During Spontaneous Attacks of Cluster Headache: Evaluation by Spectral Analysis of Heart-Rate Fluctuations

Twenty-four hour ECG Holter and blood-pressure monitorings were performed in eight patients suffering from cluster headache. Spectral analysis of heart-rate fluctuation was used to assess the autonomic balance under basal conditions, after head-up tilt, and during a spontaneous attack. Normal autonomic balance was found at rest and during sympathetic activation obtained with head-up tilt in the interparoxysmal period. Before the onset of headache, an increase in the low-frequency (LF) component of the power spectrum was apparent in all patients. This sign of sympathetic activation was followed by an increase in the high-frequency (HF) component that developed about 2000 beats after the onset of headache and rapidly overcame the LF component until the end of pain. Significant differences were found when comparing the spectral parameters [total spectral values (TP), power of the LF and HF components and LF/HF ratio] obtained before, during and after headache. During the attack, blood pressure increased and heart rate decreased in all subjects. There appears to be a primary activation of both sympathetic and parasympathetic functions in cluster headache attacks. The sympathetic component seems to be involved mostly in the development of the attack, whereas the parasympathetic activation seems to occur, following the onset of the attack, independently of the pain.

A multivariate time-variant AR method for the analysis of heart rate and arterial blood pressure

This paper approaches the problem of short-term mechanisms that regulate heart rate and blood pressure variability signals, by focusing the evident changes of their frequency content during transients (dynamic situations in which the behaviour of these control mechanisms may vary on a beat-to-beat basis). In this study, we suggest an autoregressive time-variant spectral estimation method, which is able to follow such dynamic changes in the signals. This method has also been extended to a multivariate approach in order to take into account more than one process at a time, and to assess the mutual influences between the different controlling systems. The algorithms successfully tested on simulated series have also been used to analyse series recorded during a vaso-vagal syncope episode in a tilt manoeuvre and a physical exercise stress test protocol. The results show how this method is able to follow the changing dynamics of the signals on the basis of a closed-loop model of their interaction on a beat-to-beat basis. After a proper identification procedure of the blocks forming the model, it is possible, therefore, to obtain the classical spectral parameters and the gain of the transfer function between the signals. Such parameters constitute new time series that describe the physiopathology of the cardiovascular control systems, even during non-stationary epochs.

Autonomic nervous activity during sleep in middle cerebral artery infarction.

No data are available on the autonomic system during sleep in patients with stroke. The purpose of this study was to determine the influence of acute ischemic stroke on the autonomic cardiovascular system during sleep, and to correlate autonomic activity with the clinical status of patients. Ten patients with ischemic stroke in the middle cerebral artery were studied by means of an all-night polysomnographic recording within the 1st week of the onset of symptoms and at the 3-week follow-up examination. Power spectrum analysis of the heart rate variability was performed using an autoregressive algorithm in 180 consecutive electrocardiographic RR intervals. Spectral power was calculated in 3 main frequency bands: high frequency (HF), 0.15–0.4 Hz; low frequency (LF), 0.04–0.15 Hz; very low frequency (VLF), <0.04 Hz. The data were compared with those of 10 age-matched controls. A significant increase in VLF (p < 0.0005) and a decrease in HF (p < 0.0002) components were found in ischemic stroke patients. The sympathetic-parasympathetic balance (VLF + LF/HF) was higher in patients than controls (p < 0.005). However, these components changed significantly during sleep, revealing a physiological pattern. These power spectral data were still present at the 3-week follow-up. The 4 patients who developed cardiac arrhythmias showed higher sympathetic-parasympathetic balance than patients without arrhythmias (p < 0.05). These data suggest a sympathetic predominance in patients with acute ischemic stroke during sleep. However, the flexible and dynamic properties of the autonomic nervous system are preserved. Cardiac arrhythmias following stroke may be related to the degree of sympathetic predominance.

Direct stimulation of the autonomic nervous system modulates activity of the brain at rest and when engaged in a cognitive task

The effect of autonomic perturbation (AP) on the central nervous system functioning is still largely unknown. Using an automated neck suction device to stimulate the carotid mechanoreceptors in the carotid sinus (parasympathetic pathway), operated synchronously with functional magnetic resonance imaging (fMRI) acquisition, we investigated the effects of AP on the activity of the brain at rest and when engaged in a visuo‐spatial attention task. ECG was always recorded to index changes in autonomic function. At rest, AP induced increased activation in the insula and in the amygdala, which have been previously associated with the autonomic control and emotion processing, as well as in the caudate nucleus and in the medial temporal cortex, both implicated in cognitive functions. Despite a preserved performance during visuo‐spatial attention task, AP induced increased reaction times and a positive modulation on the activation of the right posterior parietal cortex, the occipital cortex, the periaquiductal gray, and nuclei of the brainstem. We speculate that this modulation of brain activity represents, at different anatomical levels, a compensation mechanism to maintain cognitive efficiency under parasympathetic stimulation, which is traditionally considered as the system for energy regain and storage. In conclusion, this study provides the first evidence of a dynamic interaction between AP and higher level functions in humans. Hum Brain Mapp, 2013.

Ganglionated plexi ablation in right atrium to treat cardioinhibitory neurocardiogenic syncope

Cardioinhibitory neurocardiogenic syncope (CNS) is caused by inappropriately trigger-activated cardiac reflex which finally precipitates asystole, sinus bradycardia, or atrioventricular (AV) block [1]. Despite young patients affected by CNS have an excellent prognosis when electro-structural heart diseases are excluded [2], their quality of life may be seriously affected by recurrent episodes [2, 3]. Cardiac pacing might help to control symptoms and therefore is considered in patients aged more than 40 years old with recurrent episodes and documented cardioinhibitory response [1, 4]. In young individuals, the role of cardiac pacing is dubious due to predicted frequent device substitutions and adverse ventricular remodeling over time. Recently, radiofrequency (RF) biatrial ablation of ganglionated plexi (GP) has showed promising results in the shortand long-term treatment of reflex syncope, functional atrioventricular block, or sinus node dysfunction [5, 6]. We report the case of two patients with frequent episodes of CNSwithmarked cardioinhibitory response at head-up tilt test (HUT) who remained highly symptomatic despite common therapeutic measures. Given the young age of the patients, we decided to attempt, on the basis of previous models of atrial denervation [5], a transcatheter ablation at anatomical sites of the right atrial GP, to evaluate if vagal denervation was effective to prevent or to reduce syncope episodes, delaying as long as possible the timing for pacemaker implantation.

Autonomic cardiovascular function and baroreflex sensitivity in patients with cervical dystonia receiving treatment with botulinum toxin type A

ObjectiveTo investigate possible changes in autonomic cardiovascular regulation and cardiopulmonary baroreflex sensitivity in patients with primary cervical dystonia receiving chronic treatment with botulinum toxin type A.MethodsShort-term power spectral analysis of heart rate and systolic blood pressure variability, high-frequency and low-frequency oscillations of heart rate variability, low frequency/high frequency ratio and baroreflex sensitivity (α index) were measured in 12 patients with cervical dystonia before and 2–4 weeks after botulinum toxin type A injection and compared with normative data.ResultsBefore treatment, at rest, patients had significantly lower high frequency power than healthy subjects (p < 0.01), whereas no differences were found in low frequency power. Botulinum toxin injection in patients induced no changes in either power frequency. In patients before treatment and healthy subjects the low frequency oscillatory components increased similarly from rest to tilt (p < 0.01), but tilt induced lower low frequency values in patients than in healthy subjects (p < 0.01). In patients before treatment, the high frequency variations from rest to tilt remained unchanged, whereas in healthy subjects they decreased significantly (p < 0.01). Botulinum toxin type A injection in patients induced no changes in low frequency or high frequency powers. In patients before treatment the low frequency/high frequency ratio increased slightly from rest to tilt, but in healthy subjects increased significantly (p < 0.01). Botulinum toxin type A left the pretreatment low frequency/high frequency ratio unchanged. The α-index measured at rest in patients before treatment was lower than in healthy subjects (p<0.05), whereas during tilt was similar in both groups. The α-index measured after botulinum toxin injection in patients remained unchanged at rest and during tilt.ConclusionsPatients with cervical dystonia receiving treatment with botulinum toxin type A have mild, subclinical abnormalities in autonomic cardiovascular regulation and cardiopulmonary baroreflex sensitivity. These changes do not worsen after acute botulinum toxin type A injection.