Depth of SCUBA Diving Affects Cardiac Autonomic Nervous System

The present study investigated the influence of SCUBA dives with compressed air at depths of 10 and 20 m on ECG-derived HRV parameters in apparently healthy individuals. We hypothesized that cardiac sympathetic activity (measured by HRV parameters) adapts proportionally to diving depth, and that both time- and frequency-domain parameters are sensitive enough to track changes in cardiac ANS function during diving activities and subsequently during the recovery period. Eleven healthy middle-aged recreational divers (nine men and two women, age 43 ± 8, all nonsmokers) volunteered to participate in the present study. The participants (all open-circuit divers) were equipped with dry suits and ECG Holter devices and were later randomly assigned to dive pairs and depths (10 m vs. 20 m), and each participant served as his or her own control. No interaction effects (diving depth x time epoch) were found for the most commonly used HRV markers. More precisely, in response to two different diving protocols, a significant post hoc effect of time was observed for HR and SDNN, as these parameters transiently decreased during the dives and returned to baseline after ascent (p < 0.001). The ULF, VLF (p < 0.003), TP, and LF parameters decreased significantly during the dives, while HF significantly increased (p < 0.003). SCUBA diving apparently challenges the cardiac ANS, even in healthy individuals. The observed changes reveal possible underwater methods of influencing the parasympathetic activity of the heart depending on the depth of the dive. These results identify autonomic nervous system markers to track the cardiovascular risk related to diving and point to the possibility of tracking cardiovascular system benefits during underwater activities in selected patients.

A Lower Level of Post-Vaccinal Antibody Titer against Influenza Virus A H1N1 May Protect Patients with Autoimmune Rheumatic Diseases from Respiratory Viral Infections

Background and Objectives: The concentration of antibodies against virus influenza A H1N1 in the titer (≥1:32) positively correlates with resistance to flu in healthy persons. In elderly and immune-compromised patients, an influenza vaccine may be less immunogenic. Hypothesis: A lower post-vaccinal antibody titer (≥1:16) may be sero-protective against respiratory viral infections in patients with autoimmune rheumatic diseases. Materials and Methods: Fifty patients with autoimmune rheumatic diseases (Systemic Lupus Erythematosus—24; Rheumatoid Arthritis—15; and Sjögren’s Syndrome—11), who were at least 65 years old or whose relative disease duration (disease duration/age) was greater than 1/8, were examined. Thirty-four of them were vaccinated with a trivalent inactivated non-adjuvant influenza vaccine. The antibody concentration against influenza virus A H1N1 was measured using the standardized hemagglutination inhibition test and patients who got any respiratory viral infection were registered. To test the hypothesis, a correlative analysis was applied, followed by a binary logistic regression that included potential confounding variables, such as age, disease duration and therapy (personal/health-related conditions). Results: Vaccinated patients were significantly less affected by respiratory viral infections (21% vs. 75%). The lower titer considered (≥1:16) was significantly present more often among vaccinated patients (68% vs. 6%). The correlation between its presence/absence and that of respiratory viral infections was –0.34 (p < 0.05). The binary logistic regression evidenced the relevance of this correlation, confirming the hypothesis. Vaccination was associated with the 87.3% reduction in the likelihood of getting respiratory viral infections, whereas the lower antibody titer (≥1:16) was associated with the 77.6% reduction in the likelihood of getting respiratory viral infections. The vaccine was well tolerated by all patients and after vaccination no exacerbation of the underlying disease was observed. Conclusions: A lower antibody titer (≥1:16) against influenza virus A H1N1 could be protective against respiratory viral infections for certain autoimmune rheumatic diseases patients, which confirms the clinical effectiveness of influenza vaccination.

Assessment of Autonomic Nervous System Dysfunction in the Early Phase of Infection With SARS-CoV-2 Virus

BACKGROUND

We are facing the outburst of coronavirus disease 2019 (COVID-19) defined as a serious, multisystem, disorder, including various neurological manifestations in its presentation. So far, autonomic dysfunction (AD) has not been reported in patients with COVID-19 infection.

AIM

Assessment of AD in the early phase of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus).

PATIENTS AND METHODS

We analyzed 116 PCR positive COVID-19 patients. After the exclusion of 41 patients with associate diseases (CADG), partitioned to patients with diabetes mellitus, hypertension, and syncope, the remaining patients were included into a severe group (45 patients with confirmed interstitial pneumonia) and mild group (30 patients). Basic cardiovascular autonomic reflex tests (CART) were performed, followed by beat-to-beat heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) analysis, along with baroreceptor sensitivity (BRS). Non-linear analysis of HRV was provided by Poincare Plot. Results were compared to 77 sex and age-matched controls.

RESULTS

AD (sympathetic, parasympathetic, or both) in our study has been revealed in 51.5% of severe, 78.0% of mild COVID-19 patients, and the difference compared to healthy controls was significant (p = 0.018). Orthostatic hypotension has been established in 33.0% COVID-19 patients compared to 2.6% controls (p = 0.001). Most of the spectral parameters of HRV and BPV confirmed AD, most prominent in the severe COVID-19 group. BRS was significantly lower in all patients (severe, mild, CADG), indicating significant sudden cardiac death risk.

CONCLUSION

Cardiovascular autonomic neuropathy should be taken into account in COVID-19 patients' assessment. It can be an explanation for a variety of registered manifestations, enabling a comprehensive diagnostic approach and further treatment.

Assessment of Autonomic Nervous System Dysfunction in the Early Phase of Infection With SARS-CoV-2 Virus

BACKGROUND

We are facing the outburst of coronavirus disease 2019 (COVID-19) defined as a serious, multisystem, disorder, including various neurological manifestations in its presentation. So far, autonomic dysfunction (AD) has not been reported in patients with COVID-19 infection.

AIM

Assessment of AD in the early phase of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus).

PATIENTS AND METHODS

We analyzed 116 PCR positive COVID-19 patients. After the exclusion of 41 patients with associate diseases (CADG), partitioned to patients with diabetes mellitus, hypertension, and syncope, the remaining patients were included into a severe group (45 patients with confirmed interstitial pneumonia) and mild group (30 patients). Basic cardiovascular autonomic reflex tests (CART) were performed, followed by beat-to-beat heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) analysis, along with baroreceptor sensitivity (BRS). Non-linear analysis of HRV was provided by Poincare Plot. Results were compared to 77 sex and age-matched controls.

RESULTS

AD (sympathetic, parasympathetic, or both) in our study has been revealed in 51.5% of severe, 78.0% of mild COVID-19 patients, and the difference compared to healthy controls was significant (p = 0.018). Orthostatic hypotension has been established in 33.0% COVID-19 patients compared to 2.6% controls (p = 0.001). Most of the spectral parameters of HRV and BPV confirmed AD, most prominent in the severe COVID-19 group. BRS was significantly lower in all patients (severe, mild, CADG), indicating significant sudden cardiac death risk.

CONCLUSION

Cardiovascular autonomic neuropathy should be taken into account in COVID-19 patients' assessment. It can be an explanation for a variety of registered manifestations, enabling a comprehensive diagnostic approach and further treatment.

Hydrogen transfer reaction: Bond formation and bond cleavage through the eyes of interacting quantum atoms

Hydrogen transfer from hydroquinone to the methoxy radical was studied using the density functional theory. The energy decomposition technique, interacting quantum atoms, was employed for a detailed investigation of the changes that the bonds of interest go through along the minimum energy path in the vicinity of the transition state. The whole system was divided either into two or three fragments. The two-fragment analysis enabled investigation of the bond that is formed or the one that is cleaved by defining the fragments as reactants and as products, respectively. The three-fragment analysis (the fragments being semiquinone, hydrogen atom and methoxy radical) was used for the simultaneous analysis of the two phenomena, bond cleavage and bond formation. Additionally, it enabled the interaction between the particle that donates the hydrogen atom and the one that accepts it to be investigated. This interaction is characterized by attractive non-classical and repulsive classical interactions. It was demonstrated that the transferring hydrogen atom undergoes the most pronounced energy changes and gives the largest contribution to the deformation energy.

Relationship between cerebrovascular and valvular manifestations in a Serbian cohort of patients with antiphospholipid syndrome

OBJECTIVES

Antiphospholipid syndrome (APS) may manifest itself as a primary (PAPS) or secondary disease, most commonly in the context of systemic lupus erythematosus (SLE) with various neurological and cardiac manifestations in its occurrence. The objective of this study was to investigate the relationship between cerebrovascular (stroke and transient ischaemic attack (TIA)) and valvular manifestations in a Serbian cohort of APS patients.

METHODS

This is cross sectional study of 508 APS patients: 360 PAPS and 148 APS patients associated with SLE (SAPS). aPL analysis included detection of anticardiolipin antibodies (aCL: IgG/IgM), anti-ß2glycoprotein I (ß2GPI: IgG/IgM), and LA.

RESULTS

The prevalence of valvular manifestations (valvular vegetations and valvular thickening and dysfunction not related to age) in our cohort was significantly higher in SAPS group. (28.4% vs. 8.6%, p=0.0001). Age was strong predictor for stroke and TIA occurrence in both groups as well as gender (stroke more likely occurred in male SAPS and TIA in male PAPS patients). Presence of ß2GPI IgG in SAPS patients was significantly related to stroke (p=0.018), whereas ß2GPI IgG negative PAPS patients were more prone to TIA. Valvular manifestations were significantly related to TIA in both groups of patients and were independent risk factors for TIA in PAPS (OR 3.790 CI 1.597-8.998 p=0.003).

CONCLUSIONS

In this cross-section analysis of a large cohort of Serbian APS patients, there was a strong relationship between valvular and cerebrovascular manifestations, suggesting a more cautious approach regarding neurological symptoms, especially in PAPS patients with valvular vegetations present.

Correlation between ECG changes and early left ventricular remodeling in preadolescent footballers

The aim of this study was to assess the early electrocardiogram (ECG) changes induced by physical training in preadolescent elite footballers. This study included 94 preadolescent highly trained male footballers (FG) competing in Serbian Football League (minimum of 7 training hours/week) and 47 age-matched healthy male controls (less than 2 training hours/week) (CG). They were screened by ECG and echocardiography at a tertiary referral cardio center. Sokolow-Lyon index was used as a voltage electrocardiographic criterion for left ventricular hypertrophy diagnosis. Characteristic ECG intervals and voltage were compared and reference range was given for preadolescent footballers. Highly significant differences between FG and CG were registered in all ECG parameters: P-wave voltage (p < 0.001), S-wave (V1 or V2 lead) voltage (p < 0.001), R-wave (V5 and V6 lead) voltage (p < 0.001), ECG sum of S V_1-2 + R V_5-6 (p < 0.001), T-wave voltage (p < 0.001), QRS complex duration (p < 0.001), T-wave duration (p < 0.001), QTc interval duration (p < 0.001), and R/T ratio (p < 0.001). No differences were found in PQ interval duration between these two groups (p > 0.05). During 6-year follow-up period, there was no adverse cardiac event in these footballers. None of them expressed pathological ECG changes. Benign ECG changes are presented in the early stage of athlete's heart remodeling, but they are not related to pathological ECG changes and they should be regarded as ECG pattern of LV remodeling.

Translation of the Medical Fear Survey to Serbian: psychometric properties

BACKGROUND

Medical Fear Survey (MFS) is an instrument designed for measuring fear of medical and related treatments.

OBJECTIVE

Aim of the present study was MFS translation into Serbian, measurement of its psychometric properties and MFS validation using other Blood-injury-injections and related stimuli instruments that have been translated from English into Serbian.

METHOD

After obtaining permission from the author of the original MFS, double forward translation from English to Serbian and backward translation to English were conducted in ten steps, according to International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines. Reliability, factorial analysis and concurrent validation of Serbian version of MFS were conducted on a sample of 485 medical or pharmacy students at University of Kragujevac, Serbia.

RESULTS

Serbian version of MFS showed high internal consistency with a Cronbach's alpha 0.968 and good temporal stability after testing-and-retesting (Spearman's correlation coefficient 0.838, and intraclass correlation coefficient 0.877). Factorial analysis confirmed the same five factors demonstrated in the original English version: fear of mutilated bodies (10 items), fear of blood (11 items), fear of injections and blood draws (9 items), fear of sharp objects (10 items), and fear of medical examinations and physical symptoms (10 items). The total score of MFS correlated significantly with the total scores of Injection Phobia Scale-Anxiety (Spearman's correlation coefficient 0.391, p <0.001), Blood/Injection Fear Scale (Spearman's correlation coefficient 0.502, p <0.001) and Medical Avoidance Survey (Spearman's correlation coefficient 0.396, p <0.001).

CONCLUSIONS

Serbian version of the 50-item MFS showed similar psychometric properties as the original English version of this scale, with the same factorial structure. It could be used for measurement of fear of medical and related treatments in Serbian socio-cultural milieu, preferably self-administered. Hippokratia 2016, 20(1): 44-49.

Cardiac autonomic dysfunction in patients with gastroesophageal reflux disease

AIM: To investigate autonomic nervous function in patients with a diagnosis of gastroesophageal reflux disease (GERD).

METHODS: The investigation was performed on 29 patients (14 men), aged 18-80 years (51.14 ± 18.34), who were referred to our Neurocardiology Laboratory at the Clinical and Hospital Center “Bezanijska Kosa” with a diagnosis of GERD. One hundred sixteen healthy volunteers matched in age and sex with the examinees served as the control group. The study protocol included the evaluation of autonomic function and hemodynamic status, short-term heart rate variability (HRV) analysis, 24 h ambulatory ECG monitoring with long-term HRV analysis and 24 h ambulatory blood pressure monitoring.

RESULTS: Pathologic results of cardiovascular reflex test were more common among patients with reflux compared to the control group. Severe autonomic dysfunction was detected in 44.4% of patients and in 7.9% of controls (P < 0.001). Parameters of short-term analysis of RR variability, which are the indicators of vagal activity, had lower values in patients with GERD than in the control group. Long-term HRV analysis of time-domain parameters indicated lower values in patients with reflux disease when compared to the control group. Power spectral analysis of long-term HRV revealed lower low- and high-frequency values. Detailed 24 h ambulatory blood pressure analysis showed significantly higher values of systolic blood pressure and pulse pressure in the reflux group than in the control group.

CONCLUSION: Patients with GERD have distortion of sympathetic and parasympathetic components of the autonomic nervous system, but impaired parasympathetic function appears more congruent to GERD.

Autonomic nervous system adjustment (ANSA) in patients with hypertension treated with enalapril

BACKGROUND AND AIM

Reduced baroreflex sensitivity (BRS), decreased heart rate variability (HRV) and increased blood pressure (BP) variability have serious consequences for target organ damage in patients with hypertension, beside the BP level. The study was aimed to evaluate acute and long-term effects of enalapril, on BRS and HRV in individuals with prehypertension and mild essential hypertension.

METHODOLOGY

We enrolled in the study 85 patients (male 53%, age 42-67) with prehypertension and mild hypertension (systolic blood pressure ≥120 mmHg or diastolic blood pressure ≥80 mmHg). All patients were tested before, 30 minutes after first oral enalapril dose and three weeks after monotherapy with enalapril. The methodology included: beat to beat HRV analysis, BRS measurements with sequence technique, ECG with short term and 24-hour HRV analysis, 24-hour ambulatory blood pressure monitoring with systolic and diastolic BP variability analysis. Patients were divided into groups with sympathetic or vagal predominance based on Autonomic Nervous System Adjustment (ANSA) method.

RESULTS

1) 30 min after initial dose enalapril significantly and effectively reduced systolic BP with shift towards the parasympathetic predominance as reflected in decreased heart rate and low frequency (LF) to high frequency (HF) ratio (LF/HF ratio); 2) chronic enalapril therapy effectively reduced BP, including both systolic BP, diastolic BP and pulls pressure, had positively influence on dipping status, but did not significantly change BP variability; 3) in the whole patient group chronic enalapril therapy did not significantly change HRV, but it significantly decreased LF(nu) in the patient with high basal sympathetic activity, and significantly increased LF(nu) in patients with high basal vagal activity; enalapril also significantly decreased HF (nu) in patients with high basal parasympathetic activity; 4) despite initial, transit changes in maximal and minimal slope of BRS enalapril did not significantly affect sensitivity of spontaneous baroreflex activation.

CONCLUSION

Initial enalapril dose significantly reduced systolic BP and had beneficial effects on autonomic tone and baroreflex sensitivity. Chronic enalapril therapy effectively reduced BP without significant influence on BRS, but had significant autonomic effects on HRV when initial autonomic profile in each patient was analyzed by ANSA. Analyzed by ANSA method chronic enalapril therapy managed to retrieve disturbed sympathovagal balance and established autonomic equilibrium.

Impairment of cardiac autonomic control in patients with amyotrophic lateral sclerosis

The aim of this study was to investigate autonomic cardiac control in patients with amyotrophic lateral sclerosis (ALS). Fifty-five patients with sporadic ALS (28 female and 27 male; average age 56.00 +/- 10.34 years) were compared to 30 healthy controls (17 female and 13 male; average age 42.87 +/- 11.91 years). Patients with previous history of cardiac disease, diabetes mellitus, and impaired respiratory function were excluded from the study. Cardiovascular autonomic tests according to Ewing, power spectrum analysis of RR variability (low- and high-frequency bands - LF and HF, LF/HF index), real-time beat-to-beat ECG signal monitoring with heart rate variability analysis and baroreflex function analysis were carried out in all patients. Time-domain parameters of heart rate variability (mean RR interval, SDNN, SDANN, SDNN index, rMSSD and pNN50%) were obtained from 24-h ECG monitoring. ALS patients had a significantly higher score of sympathetic (p <0.01) and parasympathetic (p <0.001) dysfunction, as well as of the overall score of autonomic dysfunction (p <0.001). LF/HF index was significantly increased; baroreflex sensitivity and time-domain parameters of heart rate variability were highly significantly decreased in ALS patients (p <0.001). Our results demonstrated impaired cardiac autonomic control in ALS with marked parasympathetic dysfunction and sympathetic predominance.

Heart rate variability in children with exercise-induced idiopathic ventricular arrhythmias

Ventricular arrhythmias (VAs) are common pediatric rhythm disorders requiring comprehensive laboratory evaluation. Although usually idiopathic, implying a benign character and favorable prognosis, the initial clinical approach is still not established in all cases. Considering their prognostic significance, exercise-induced (precipitated or aggravated) VAs usually require additional diagnostics, treatment, and follow-up. A number of reports have presented experimental and clinical evidence that increased sympathetic activity can initiate, or at least facilitate, VAs. Recent data highlight the relationship between exercise-induced idiopathic VAs (IVAs) and the long-term risk of cardiovascular death. The aim of this study was to assess the utility of heart rate variability (HRV) analysis as a noninvasive method for estimating autonomic nervous activity in children with exercise induced IVAs. The study included 42 children with IVAs, who were divided into two groups: children with exercise induced (precipitated or aggravated) IVAs and children with exercised-suppressed IVAs. Time-domain HRV parameters were analyzed from 24-h ambulatory electrocardiography recordings, and the majority of children underwent an exercise stress test using the McMaster protocol. The results of this study showed no significant changes in parasympathetic index, i.e., the square root of the mean of the sum of the squares of the differences between adjacent NN intervals (the length between two successive heartbeats) between the groups examined. On the other hand, we observed diminished time-domain values for the standard deviation of all adjacent NN intervals, as well as diminished time-domain values for standard deviation of the averages of NN intervals in all 5-min segments in the group of children with exercise-induced IVAs, implicating increased sympathetic activity in such individuals. HRV analysis could be a helpful diagnostic method, giving useful information regarding cardiac autonomic control in some children with exercise-induced IVAs.

Gender differences in acute coronary syndrome in Serbia before organized primary PCI network service

INTRODUCTION

Numerous studies were focused on coronary artery disease, most of them in the male population and it seems that data on gender differences in CAD were extrapolated from these studies.

GOAL

The multi-center prospective study was designed to analyze gender differences in features, clinical presentation, and early in-hospital mortality in patients with acute coronary syndrome (ACS) admitted to coronary units in 50 hospitals in Serbia, during a 12 month-period.

METHODS

The data were collected from the central register of ACS, analyzed with respect to gender differences. The study protocol included all consecutive patients with diagnosis of ACS. In the study 12,094 patients were analyzed, 7639 men and 4455 women. Women were significantly older than men in all ACS manifestations (p < 0.001).

RESULTS

Incidence of myocardial infarction (MI) in women was the highest between the 7th and 8th life decade, while in men the highest incidence is observed between their sixties and seventies. Equalization in the incidences of MI in men and women is observed between the sixth and seventh life decades. There were significant differences in the incidence of fibrinolytic therapy and heart failure (p < 0.001) in favor of women. Women with unstable angina and NSTEMI had higher in-hospital mortality (2.4% vs. 1.7% and 9.0% vs. 7.1%, respectively), without statistical significance, while in STEMI the difference was highly statistically significant (16.1% compared to men 10.1), p < 0.001.

DISCUSSION

The mean age of the greatest frequency of occurrence of MI has been shifted five years earlier in the population of women, different from other studies related to the analysis of MI by gender differences.

CONCLUSION

Female mortalitywas significantly higher compared to the male population, thus more aggressive therapy should be administrated.

Autonomic dysfunction in alcoholic cirrhosis and its relation to sudden cardiac death risk predictors

Patients with liver cirrhosis have autonomic dysfunction and complex cardiovascular changes. Increases risk for sudden cardiac death (SCD) was recently recognized in liver cirrhosis. This study analyzed risk predictors for SCD related to autonomic dysfunction in patients with alcoholic liver cirrhosis (ALC). Twenty five patients with ALC were examined and compared with healthy control group. Cardiovascular autonomic reflex tests, comprehensive ECG with QTc interval, late potentials, short-term heart rate variability (HRV) analysis (time domain, spectral and nonlinear-Poincare plot analysis) and 24-h Holter ECG with long-term HRV analysis were done. According to autonomic reflex tests patients with ALC had high incidence (56%) of severe autonomic dysfunction, manifested as pronounced damage of vagal function. Patients had significantly depressed HRV (SDNN, SDANN, triangular index, LF and HF) and more frequently had serious arrhythmias, prolonged QTc and Poincare plot in a shape of dot (p < 0.001). In patient group QTc significantly inversely correlated with spectral components from short-term HRV analysis (ln(LF): r = -0.53, ln(HF): r = -0.47; p < 0.05), and Lown class significantly correlated with total autonomic function score (r = 0.64, p = 0.04). This study indicates that in ALC autonomic neuropathy with vagal impairment and sympathetic predominance is related to SCD risk predictors and onset of serious ventricular arrhythmias.

Detection of massive pulmonary embolism by transesophageal echocardiography

Transesophageal echocardiography is a new echocardiographic technique with indications that are still expanding and being redefined. Recently, the usefulness of transesophageal echocardiography in pulmonary embolism has been demonstrated in several case reports. In this article, we present 3 cases with pulmonary embolism diagnosed by transesophageal echocardiography and discuss its diagnostic value in this clinical setting.