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.

ECG Ventricular Repolarization Dynamics during Exercise: Temporal Profile, Relation to Heart Rate Variability and Effects of Age and Physical Health

Periodic repolarization dynamics (PRD) is a novel electrocardiographic marker of cardiac repolarization instability with powerful risk stratification capacity for total mortality and sudden cardiac death. Here, we use a time-frequency analysis approach to continuously quantify PRD at rest and during exercise, assess its dependence on heart rate variability (HRV) and characterize the effects of age (young adults/middle-aged adults/older adults), body mass index (non-overweight/overweight) and cardiorespiratory fitness level (fit/unfit). Sixty-six male volunteers performed an exercise test. RR and dT variabilities (RRV, dTV), as well as the fraction of dT variability unrelated to RR variability, were computed based on time-frequency representations. The instantaneous LF power of dT (PdTV), representing the same concept as PRD, and of its RRV-unrelated component (PdTVuRRV) were quantified. dT angle was found to mostly oscillate in the LF band. Overall, 50–70% of PdTV was linearly unrelated to RRV. The onset of exercise caused a sudden increase in PdTV and PdTVuRRV, which returned to pre-exercise levels during recovery. Clustering analysis identified a group of overweight and unfit individuals with significantly higher PdTV and PdTVuRRV values at rest than the rest of the population. Our findings shed new light on the temporal profile of PRD during exercise, its relationship to HRV and the differences in PRD between subjects according to phenotypic characteristics.

Water cycle changes in the headwater regions of the Yangtze River and Yellow River basins during the past three decades

&lt;p&gt;Yangtze River and Yellow River are the two most important rivers in China. Long-term observation shows that runoff ratio (i.e., runoff/precipitation, denoted as RR) in the headwater of both Yangtze River (HYZR) and Yellow River (HYER) has experienced significant decrease and then increase trend (referred as V-change) during the period 1980-2015. Over the whole period, RR of the HYER shows significant decreasing trend (-0.02/10a, p &lt; 0.05), while it is not significant for the HYZR. Changes in RR in both HYZR and HYER pose great challenge on runoff predication and water management in the downstream. However, driven mechanisms underlying the V-change of RR are still unclear. Here, based on ground-based and remote sensing datasets, both terrestrial and atmospheric water budgets are investigated to understand the evolution of RR in the headwater regions of Yangtze River and Yellow River. Terrestrial water budgets are for evaporation estimation and water cycle analysis. Atmospheric water budgets are used to calibrate the estimated evaporation. Results show that TWS-REC agrees well with observed total water storage (TWS-GRACE) in both HYZR (r = 0.94, NSE = 0.83) and HYER (r = 0.93, NSE = 0.83) over the period of 2003-2012. Estimated evaporation from both terrestrial water balance and atmospheric water balance method also agree well with each other in the HYZR (r = 0.89, NSE = 0.80) and in the HYER (r = 0.88, NSE = 0.79) over the period of 2000-2015. It suggests that reconstructed TWS and estimated evaporation are reliable for analyzing long-term water cycle in the study areas. Both the ratio of the estimated evaporation to precipitation (ER) in two basin increase first and then decreased during the study period. The correlation coefficients between ER and RR in the HYZR and HYER are -0.63 and -0.79, respectively, presenting that RR variability could be mainly caused by the evolution ER. Meanwhile it also indicates the nonignored role of total water storage (TWS) changes in RR variability in the two basin. TWS-REC in both regions have experienced significant increasing with rate of 26 mm/10a (HYZR, p &lt; 0.05) and 17mm/10a (HYER, p &lt; 0.05), later of which is the main reason of downward trend of RR in HYER. Further analysis indicates that changes in ER are resulted from comprehensive effects of precipitation variability (26.4mm/10a, p &lt; 0.05 in HYZR and 3.5mm/10a p &gt; 0.1 in HYER) and of dramatic climate warming (0.6&amp;#8451;/10a, p &lt; 0.05 in HYZR and 0.5&amp;#8451;/10a, p &lt; 0.05 in HYER). TWS changes in both basin are positively related with dramatic temperature rising and significant vegetation greening. It means that annual fluctuation of precipitation-runoff process (i.e., V-change RR) has affected negatively by climate warming and vegetation greening in the HYZR and HYER. These findings can advance our understanding of the runoff ratio evolution and water cycle in the headwater of Yangtze River and Yellow River and it is also important for ecological conservation strategy and downstream water resources management.&lt;/p&gt;

Abstract P505: Real-world Data Validation Of A Novel P-wave Based Automatic Atrial Fibrillation Detection Algorithm

Background: Automatic ECG algorithms using only RR-variability in ECG to detect AF have shown high false positive rates. By including P-wave presence in the algorithm, research has shown that it can increase detection accuracy for AF. Methods: A novel RR- and P-wave based automatic detection algorithm implemented in the Coala Heart Monitor ("Coala", Coala Life AB, Sweden) was evaluated for detection accuracy by the comparison to blinded manual ECG interpretation based on real-world data. Evaluation was conducted on 100 consecutive anonymous printouts of chest- and thumb-ECG waveforms, where the algorithm had detected both irregular RR-rhythms and strong P-waves in either chest or thumb recording (non-AF episodes classified by algorithm as Category 12).The recordings, without exclusions, were generated from 5,512 real-world data recordings from actual Coala users in Sweden (both OTC and Rx users) during the period of March 5 to March 22, 2019, with no control or influence by the researchers or any other organization or individual. The prevalence of cardiac conditions in the user population was unknown.The blinded recordings were each manually interpreted by a trained cardiologist. The manual interpretation was compared with the automatic analysis performed by the detection algorithm to determine the number of additional false negative indications for AF as presented to the user. Results: The trained cardiologist manually interpreted 0 of the 100 recordings as AF. Manual interpretation showed that the novel automatic AF algorithm yielded 0 % False Negative error and 100 % Negative Predictive Value (NPV) for detection of AF. Irregular RR-rhythms were detected in 569 recordings (10 % of a total of 5,512 recordings). The 100 non-AF recordings containing both irregular RR-rhythms and strong P-waves constituted 18% of all recordings with irregular RR-rhythms. Respiratory sinus arrhythmia was the single most prevalent condition and was found in 47% of irregular RR-rhythms with strong P-waves. Conclusion: The novel, P-wave based automatic ECG algorithm used in the Coala, showed a zero percent False Negative error rate for AF detection in ECG recordings with RR-variability but presence of P-waves, as compared to manual interpretation by a cardiologist.

RR Variability in Acute Coronary Syndromes

Heart rate variability (HRV) is a simple measure that estimates cardiac autonomic modulation. Analysis in the time domain and frequency range of RR variability suggests that the negative prognosis of patients with acute myocardial infarction is related to the overall neuro-vegetative imbalance. The alteration of RR variability reflects the dysfunction of the autonomic nervous system and especially the reduction of parasympathetic tone. The results of this study confirm the association between the reduction of RR variability and the increased risk of adverse events and mortality after acute myocardial infarction. Moreover, it appears that RR variability is an independent predictor for atrial fibrillation. Keywords: RR variability, myocardial infarction, HRV, sudden cardiac death

Symbolic dynamics to discriminate healthy and ischaemic dilated cardiomyopathy populations: an application to the variability of heart period and QT interval

Myocardial ischaemia is hypothesized to stimulate the cardiac sympathetic excitatory afferents and, therefore, the spontaneous changes of heart period (approximated as the RR interval), and the QT interval in ischaemic dilated cardiomyopathy (IDC) patients might reflect this sympathetic activation. Symbolic analysis is a nonlinear and powerful tool for the extraction and classification of patterns in time-series analysis, which implies a transformation of the original series into symbols and the construction of patterns with the symbols. The aim of this work was to investigate whether symbolic transformations of RR and QT cardiac series can provide a better separation between IDC patients and healthy control (HC) subjects compared with traditional linear measures. The variability of these cardiac series was studied during daytime and night-time periods and also during the complete 24 h recording over windows of short data sequences of approximately 5 min. The IDC group was characterized by an increase in the occurrence rate of patterns without variations (0 V%) and a reduction in the occurrence rate of patterns with one variation (1 V%) and two variations (2 V%). Concerning the RR variability during the daytime, the highest number of patterns had 0 V%, whereas the rates of 1 V% and 2 V% were lower. During the night, 1 V% and 2 V% increased at the expense of diminishing 0 V%. Patterns with and without variations between consecutive symbols were able to increase the separation between the IDC and HC groups, allowing accuracies higher than 80%. With regard to entropy measures, an increase in RR regularity was associated with cardiac disease described by accuracy >70% in the RR series and by accuracy >60% in the QTc series. These results could be associated with an increase in the sympathetic tone in IDC patients.