Air Pollution Role as Risk Factor of Cardioinhibitory Carotid Hypersensitivity

Little is known about the impact of air pollution on neuroautonomic system. The authors have investigated possible influence of air pollution and outdoor temperature on the carotid sinus hypersensitivity (CSH), as main cause of neurally mediated syncope in forty-years-old subjects and older. Pollutants’ concentrations and outdoor temperature of days in which 179 subjects with recurrent syncope underwent carotid sinus massage (CSM) were analyzed. Before this manoeuvre, cardiovascular control by short period heart and blood pressure spectral duration of segment between the end of P and R ECG-waves (PeR) were registred; RR variability on the same short period ECG recordings and their spectral coherence were also analyzed. CSH was found in 57 patients (28 with cardioinhibitory response and 29 subjects showed vasodepressor reaction), while 122 subjects had a normal response. CSM performed during high ozone concentrations was associated with slightly higher risk of cardioinhibitory response (odd ratio 1.012, 95% CI 1.001–1.023, p < 0.05), but neither this or other polluting agent nor outdoor temperature seemed to influence autonomic control in basal resting condition. Thus, ozone seemed to influence response to the CSM in CSH patients and it is probably able to facilitate a cardioinhibitory response, perhaps through an increase of nerve acetylcholine release. P→PR coherence could be useful in predicting a sinus cardioinhibitory hypersensitivity in those cases when CSM is contraindicated.

Clinical Significance of the Head-Up Tilt Test in Improving Prognosis in Patients with Possible Neurally Mediated Syncope

Syncope is commonly encountered in daily clinical practice. Depending on its etiology (benign or life-threatening conditions or environmental triggers), syncope can be neurally mediated (reflex), cardiac, or orthostatic. Furthermore, neurologic disease can cause symptoms that mimic syncope. However, there is limited research on neurally mediated syncope (NMS), which is considered a benign disorder, and close follow-ups are rarely performed. NMS can cause serious clinical events, including severe trauma and car accidents. The head-up tilt test (HUTT) is the gold standard for diagnosing NMS; however, its clinical significance remains unknown, and its relevance to NMS prognosis requires further research. This retrospective study aimed to assess the clinical significance of the HUTT for NMS. We reviewed the charts of 101 patients who underwent HUTT at Tokai University Hospital in Japan between January 2016 and March 2019. During the HUTT, 72 patients (69.2%) experienced syncope. Patients were followed up for 886.1 ± 457.7 days (interquartile range: 518–1293 days). The syncope recurrence rate was 16.9%; however, no significant difference was observed between the two groups (HUTT positive vs. negative) (13.8% vs. 18.1%, p = 0.772). Four of 29 (13.9%) and two of 72 (2.8%) patients in the negative and positive HUTT groups, respectively, experienced cardiac events (p = 0.019). Negative HUTT results may assist in anticipating unexpected clinical events within a few years. A negative HUTT result may allow us to reconsider the NMS diagnosis based on clinical information. Close outpatient follow-up of patients with negative HUTT results is warranted.

Risk of neurally mediated syncope in hypothyroidism and obesity

Introduction and rationale: Thyroid hormones participate in several known mechanisms of cardiac function, being compromised in hypothyroidism (HPT), when uncontrolled, is associated with weight gain. HPT and Obesity participate in autonomic dysfunction.

Electrocardiographic Patterns in Patients with Neurally Mediated Syncope

The baseline electrocardiogram (ECG) is less informative in neurally mediated syncope (NMS) than in arrhythmic syncope. However, some of the ECG patterns present in NMS can have diagnostic and prognostic value in such patients. Electrocardiographic documentation of a syncopal spell and thus identification of the ECG changes can be performed during tilt table test (TTT) or during prolonged ECG monitoring. This work reviews the specific ECG patterns in NMS, which are primarily related to the cardioinhibitory reflex. In addition, there are other ECG findings present in patients with NMS that are being analyzed, such as increased heart rate variability as well as specific QRS voltage patterns. In addition to the diagnostic and prognostic value, these ECG patterns in NMS may help improving the selection of patients for pacemaker implant.

Diagnosis and prevention of the vasodepressor type of neurally mediated syncope in Japanese patients

We investigated circulatory dynamics in patients with vasodepressor type neurally mediated syncope (VT-NMS) by performing high-resolution Holter electrocardiography and a correlation analysis of changes in adenylate cyclase activity, blood pressure, and pulse during the head-up tilt test. Holter electrocardiography was performed for 30 patients. Adenylate cyclase activity was evaluated in lymphocytes from blood samples taken at rest and during the head-up tilt test. There was no change in autonomic nerve fluctuation during electrocardiography in VT-NMS patients, but our results showed a significant difference in blood pressure and adenylate cyclase activity between VT-NMS patients and healthy volunteers; the systolic blood pressure of VT-NMS patients decreased after 5 min, while at 10 min, the adenylate cyclase activity was the highest (0.53%) and the systolic blood pressure was the lowest (111.8 mm Hg). Pulse rates increased after 10 min. VT-NMS patients showed higher blood pressure, pulse rate, and adenylate cyclase activity during the tilt test than did healthy volunteers. In patients with syncope, standing for longer than 10 minutes may increase the risk of VT-NMS. From our results, we consider it likely that high systolic blood pressure and adenylate cyclase activity at rest cause fainting in VT-NMS patients. Our findings may be helpful for identifying individuals with a high risk of developing NMS in the healthy population.

Simultaneous Beat-To-Beat Heart Rate And Systolic Blood Pressure Variability In Patients With And Without Neurally Mediated Syncope

Background: Autonomic changes play an essential role in the genesis of neurally mediated syncope (NMS). The aim of this study was to compare the changes of the autonomic nervous system (ANS) by measuring spectral indices of beat-to-beat systolic blood pressure and heart rate variability (SBPV and HRV) in ranges of low frequency (LF), high frequency (HF), and the LF/HF ratio during head-up tilt test (HUTT) in patients with and without a syncope response. Methods: In this case-control study of 46 patients with a suspected history of unexplained syncope, data were recorded separately during the typical three phases of HUTT. Patients who developed syncope were designated as the case group and the rest as the control group. Results: Thirty one patients experienced syncope during HUTT. Resting HRV and SBPV indices were significantly lower in cases than controls. After tilting in the syncope group, both HF and LF powers of SBPV showed a significant and gradual decrease. LF/HF in HRV increased in both groups similarly during the test but in SBPV, mainly driven by oscilations in its LF power, it increased significantly more during the first two phases of the test in syncope patients only to paradoxically decrease during active tilt (p< 0.001). Conclusion: Our findings show an abnormal autonomic function in patients with syncope, both at rest and tilting. Fluctuations of spectral indices of beat-to-beat SBPV, a potential noval index of pure sympathetic activity, show an exaggerated response during tilt and its withdrawal before syncope.

Durable Physiological Changes and Decreased Syncope Burden 12 Months After Unifocal Right-Sided Ablation Under Computed Tomographic Guidance in Patients with Neurally Mediated syncope or Functional Sinus Node Dysfunction

Background - Cardio-neuromodulation (CardNM) is a cardioneuroablative approach aiming to create adequate vagolysis of the sinoatrial node through partial ablation of the anterior right ganglionated plexus. Methods - We performed an interventional study in patients with recurrent neurally mediated syncope (group A) or functional sinus node (SN) dysfunction (group B). Syncope burden, electrocardiogram, 24-h rhythm data, tilt table test, exercise test, and pharmacological challenge with atropine were assessed at baseline and at regular intervals to 12-months. Results - Fifty patients (31 in group A, 19 in group B) underwent CardNM. Mean number of syncopes during the previous 12 months was 9.7±18.2. The procedure was associated with a lower rate of syncope (−95%) and presyncope (−95%) at 12 months versus baseline ( P <0.001). Thirty-seven patients remained entirely free of syncope at 12 months, and the syncope-free survival curve remained stable between 12- and 30-month follow-up. After a mean ablation time of 8±4 min, P-P interval shortened by 247±146 ms ( P <0.001). Basal heart rate (HR) increased by 18% ( P <0.001) and remained stable between 6 and 12 months. At 12 months, mean HR increased by 12% in the entire cohort ( P <0.001), reached 23% in patients with baseline mean HR <70 bpm ( P <0.01), and did not increase in patients with baseline HR >70 bpm. Maximum HR during exercise decreased by 10 bpm at 1 month ( P <0.001) and was restored at 12 months. Conclusions - CardNM is a safe and fast treatment giving rise to a long-term partial SN vagolysis with no apparent short- or long-term safety concerns or undesirable persisting modifications of the intracardiac autonomous nervous system. The impact on vasoplegia is less clear. CardNM is associated with a good clinical outcome in most patients with neurally mediated syncope or functional SN dysfunction. These promising data require confirmation in a multicenter randomized trial.

Radiofrequency catheter denervation of sinus node: a randomized comparison of right and left atrial approach for the cardioneuroablation

Funding Acknowledgements Type of funding sources: None. Background Radiofrequency catheter ablation of superior paraseptal ganglionic plexus is an important step to eliminate the vagal modulation of sinus node for the treatment of neurally-mediated syncope. The reasonable effect can be achieved by targeting this plexus from the endocardial aspect of both right (RA) and left (LA) atria. Purpose We investigated the efficacy of RA and LA ablation in terms of sinus nodal denervation. Methods The study included 24 patients (age: 42 ± 13 years, 50% males) who underwent cardioneuroablation for recurrent cardioinhibitory syncope in general anesthesia. Right atrial semicircular lesion at the posteroseptal quadrant of superior vena cava ostium was composed of 5-6 equidistantly distributed ablation sites (30 W, 30 s, 20 ml/min). Left atrial lesion of comparable size was placed strictly contralaterally across the interatrial septum in the anterior vestibulum of a right superior pulmonary vein. Patients were randomly (1:1) assigned to RA-to-LA or LA-to-RA ablation. Sinus rate and the response to extracardiac right vagal nerve high-frequency stimulation (50 Hz, 0.05 ms, 1 V/kg [&lt;70V], 5 s) were recorded at baseline and after each ablation cluster. Results Study protocol ablations overall resulted in sinus acceleration (81 ± 13 vs. 59 ± 12 bpm, P &lt;0.0001) and attenuation of inducible sinus arrests (maximum pause: 1.2 ± 1.4 vs. 5.5 ± 3.0 s, P &lt;0.0001). Temporal development of outcome measures with the progression of ablation is shown in the Figure. There was no significant difference between study groups. Irrespective of ablation order, the first ablation cluster on average generated 77% of the final effect on sinus rate and 68% of the final effect on suppression of vagally-induced sinus pauses. Conclusions Neither RA nor LA approach is preferable for targeting the superior paraseptal ganglionic plexus. Both ablation clusters convey complementary and, in part, mutually independent effects. Biatrial cardioneuroablation seems essential for efficacious sinus nodal denervation. Abstract Figure.

The predictive value of urine specific gravity in the diagnosis of vasovagal syncope in children and adolescents

Background Vasovagal syncope (VVS) is a kind of common neurally mediated syncope in children and adolescents. Decreased blood volume is one of the pathogenesis of VVS. The diagnosis of VVS is mainly based on head-up tilt test (HUTT), but some complications may easily occur when HUTT induces syncope. To find a simple and safe VVS diagnosis method can improve the VVS diagnosis efficiency. Aims of the study This was a prospective study. The study will explore the predictive value of urine specific gravity (USG) in the diagnosis of VVS in children and adolescents. Patients and methods Ninety-seven cases (43 males and 54 females, aged 4 to 16 years old, with an average age of 10.91 ± 2.18 years old) hospitalized due to unexplained premonitory syncope or syncope and diagnosed with VVS through HUTT from September 2014 to September 2018 were selected as VVS group. During the same period, 91 cases of children and adolescents, including 45 males and 46 females, aged from 5 to 15 years old, who underwent a healthy examination were matched as a control (control group). USG was measured in both groups. Results The USG of VVS group was significantly lower than that of the control group (P < 0.01), and USG of females was lower than that of males in VVS group (P = 0.045). The sensitivity and specificity of USG in predicting VVS were evaluated by ROC curve. The area under the ROC curve was 0.751, standard error was 0.035, and 95% CI (0.683, 0.819) suggested that USG was of moderate predictive value in the diagnosis of VVS. As cut-off value of USG was 1.0185, the sensitivity and specificity and diagnostic coincidence rate of VVS were 74.39, 66.04 and 69.68%, respectively. Conclusion There are less USG in children and adolescents with VVS, especially lower USG in females. Therefore, USG has predictive value in the diagnosis of VVS in children and adolescents.