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Heart rate variability (HRV) is frequently applied in sport-specific settings. The rising use of freely accessible applications for its recording requires validation processes to ensure accurate data. It is the aim of this study to compare the HRV data obtained by the Polar H10 sensor chest strap device and an electrocardiogram (ECG) with the focus on RR intervals and short-term scaling exponent alpha 1 of Detrended Fluctuation Analysis (DFA a1) as non-linear metric of HRV analysis. A group of 25 participants performed an exhaustive cycling ramp with measurements of HRV with both recording systems. Average time between heartbeats (RR), heart rate (HR) and DFA a1 were recorded before (PRE), during, and after (POST) the exercise test. High correlations were found for the resting conditions (PRE: r = 0.95, rc = 0.95, ICC3,1 = 0.95, POST: r = 0.86, rc = 0.84, ICC3,1 = 0.85) and for the incremental exercise (r > 0.93, rc > 0.93, ICC3,1 > 0.93). While PRE and POST comparisons revealed no differences, significant bias could be found during the exercise test for all variables (p < 0.001). For RR and HR, bias and limits of agreement (LoA) in the Bland–Altman analysis were minimal (RR: bias of 0.7 to 0.4 ms with LoA of 4.3 to −2.8 ms during low intensity and 1.3 to −0.5 ms during high intensity, HR: bias of −0.1 to −0.2 ms with LoA of 0.3 to −0.5 ms during low intensity and 0.4 to −0.7 ms during high intensity). DFA a1 showed wider bias and LoAs (bias of 0.9 to 8.6% with LoA of 11.6 to −9.9% during low intensity and 58.1 to −40.9% during high intensity). Linear HRV measurements derived from the Polar H10 chest strap device show strong agreement and small bias compared with ECG recordings and can be recommended for practitioners. However, with respect to DFA a1, values in the uncorrelated range and during higher exercise intensities tend to elicit higher bias and wider LoA.

Introducción: Uno de los signos objetivables principales de la anafilaxia es la urticaria-angioedema, si bien en algunos casos la liberación de histamina a nivel sistémico ocasiona cambios vasculares y hemodinámicos sin afectación cutánea. En el transcurso de una reacción sistémica, existen cambios en el sistema nervioso autónomo, tanto simpático como parasimpático, los cuales no han sido suficientemente estudiados. Hipótesis y objetivos: En una reacción anafiláctica grave, una gran liberación de histamina al torrente sanguíneo puede producir cambios cardiovasculares antes de producir signos cutáneos. El objetivo principal de este trabajo es valorar si la detección de alteraciones agudas en el electrocardiograma mediante monitorización del paciente, que precedan a los signos cutáneos, podría ser de utilidad para un manejo más precoz de la reacción anafiláctica en las pruebas de provocación oral con alimentos en los procedimiento diagnósticos llevados a cabo por los Servicios de Alergología. Material y métodos: Se realizaría un estudio observacional descriptivo transversal en el que se recogería la actividad cardiaca de pacientes sometidos a pruebas de provocación oral controlada con alimentos, mediante un sensor de frecuencia cardiaca que se conecta al software de análisis de variabilidad de la frecuencia cardiaca (HRV) Kubios R. Introduction: Even though the main objetivable sign in an anaphilactic reaction is urticaria-angioedema, sometimes the release of histamine to the bloodstream causes vascular and hemodynamic changes without skin involvement. There are changes in the autonomic nervous system, sympathetic and parasympathetic, in case of a systemic reaction, which have not been studied enough. Hypothesis and objectives: In a severe anaphylactic reaction, a large release of histamine to the bloodstream can cause cardiovascular changes before causing cutaneous signs. The main objective will be to assess if finding early electrocardiogram alterations through patient monitoring, before any cutaneous signs could be useful for an acute management of the anaphylaxis when performing a direct provocative food or drug challenge by an Allergy department. Material and methods: A cross sectional observational study would be performed, where the cardiac activity of the patients is being measured using a heart rate sensor device, while going through a direct food oral challenge, that would be later conected to a variability analysis of the heart rate (HRV) Kubios R.

U programskom jeziku MATLAB implementirana je detekcija R zupca u EKG signalu. Izračunata je točnost algoritma kojim se vršila detekcija. Zatim je napravljena analiza varijabilnosti srčanog ritma isto u programskom jeziku MATLAB 2015a. Implementirane su metodeu vremenskoj i frekvencijskoj domeni i nelinerane metoda. Svi rezultati prikazani su u grafičkom interaktivnom sučelju za bolji vizualni pregled. We have implemented the R-peak detection in ECG signal in programming language MATLAB. The accuracy of the detection algorithm was also calculated. Then the heart rate variability analysis was performed in the MATLAB 2015a program language. Time domain, frequency domain and non-linear methods were implemented. All results are shown in the graphical user interface (GUI) for easier understanding and better visual inspection.

Background Arrhythmia can significantly alter the image quality of cardiovascular magnetic resonance (CMR); automatic detection and sorting of the most frequent types of arrhythmias during the CMR acquisition could potentially improve image quality. New CMR techniques, such as non-Cartesian CMR, can allow self-gating: from cardiac motion-related signal changes, we can detect cardiac cycles without an electrocardiogram. We can further use this data to obtain a surrogate for RR intervals (valley intervals: VV). Our purpose was to evaluate the feasibility of an automated method for classification of non-arrhythmic (NA) (regular cycles) and arrhythmic patients (A) (irregular cycles), and for sorting of common arrhythmia patterns between atrial fibrillation (AF) and premature ventricular contraction (PVC), using the cardiac motion-related signal obtained during self-gated free-breathing radial cardiac cine CMR with compressed sensing reconstruction (XD-GRASP). Methods One hundred eleven patients underwent cardiac XD-GRASP CMR between October 2015 and February 2016; 33 were included for retrospective analysis with the proposed method (6 AF, 8 PVC, 19 NA; by recent ECG). We analyzed the VV, using pooled statistics (histograms) and sequential analysis (Poincaré plots), including the median (medVV), the weighted mean (meanVV), the total number of VV values (VVval), and the total range (VVTR) and half range (VVHR) of the cumulative frequency distribution of VV, including the median to half range (medVV/VVHR) and the half range to total range (VVHR/VVTR) ratios. We designed a simple algorithm for using the VV results to differentiate A from NA, and AF from PVC. Results Between NA and A, meanVV, VVval, VVTR, VVHR, medVV/VVHR and VVHR/VVTR ratios were significantly different (p values = 0.00014, 0.0027, 0.000028, 5×10−9, 0.002, respectively). Between AF and PVC, meanVV, VVval and medVV/VVHR ratio were significantly different (p values = 0.018, 0.007, 0.044, respectively). Using our algorithm, sensitivity, specificity, and accuracy were 93 %, 95 % and 94 % to discriminate between NA and A, and 83 %, 71 %, and 77 % to discriminate between AF and PVC, respectively; areas under the ROC curve were 0.93 and 0.89. Conclusions Our study shows we can reliably detect arrhythmias and differentiate AF from PVC, using self-gated cardiac cine XD-GRASP CMR.

Electrical Cardioversion for Atrial Fibrillation. Introduction: Atrial fibrillation (AF) is characterized by an irregularly irregular ("random") heart beat. However, controversy exists whether the ventricular rhythm in AF is truly random. We investigated randomness by constructing three-dimensional RR interval plots (3D plots), allowing identification of "clustering" of RR intervals. It was hypothesized that electrical cardioversion (ECV) would be more effective in AF patients with clustering, because clustering might reflect a higher degree of organization of atrial fibrillatory activity.Methods and Results: The study group consisted of 66 patients (44 men and 22 women; mean age 68 +/- 11 years,) who were referred for ECV because of persistent AF. Twenty-four-hour Holter recordings were used to construct 3D plots by plotting each RR interval (x axis) against the previous RR interval (y axis) and the number of occurrences of each of these x,y combinations (z axis). A clustering index was calculated as the percentage of beats within the peaks in the 3D plot. Based on the 3D plots, clustering of RR intervals was present in 31 (47%) of the 66 patients. ECV was effective in restoring sinus rhythm in 29 (94%) of these 31 patients, whereas sinus rhythm was restored in only 25 (71%) of the remaining 35 patients without clustering (P = 0.020). The clustering index ranged from 8% in the 32 patients with sinus rhythm at the end of the study (4 weeks after the ECV); the clustering index in the 22 patients with a relapse of AF after effective ECV was intermediate (P = 0.034 and P = 0.042, respectively).Conclusion: This study indicates that ECV is more effective in restoring sinus rhythm in AF patients with clustering compared to patients in whom no clustering is apparent on 3D plots. In addition, the degree of clustering appears to be predictive of the overall outcome of ECV; the higher the degree of clustering, the higher the likelihood of sinus rhythm at follow-up.