Esophageal PP intervals for analysis of short-term heart rate variability in patients with atrioventricular block before and after insertion of a temporary ventricular inhibited pacemaker

Inter- and intrarater reliability of short-term measurement of heart rate variability on rest in chronic obstructive pulmonary disease (COPD)

BACKGROUND

Individuals with COPD have an imbalance of cardiac autonomic control. In this context, HRV is considered an important tool for assessing cardiac sympathetic and parasympathetic balance, however it is a dependent evaluator measure and subject to methodological biases that may compromise the interpretation of results.

OBJECTIVE

This study examines the inter- and intrarater reliability of HRV parameters derived from short-term recordings in individuals with COPD.

METHODOLOGY

Fifty-one individuals of both genders with COPD clinical diagnosis confirmed by the pulmonary function test and aged ≥50 years were included. The RR interval (RRi) were recorded during a 10 min period on supine position using a portable heart rate monitor (Polar® H10 model). The data were transferred into Kubios® HRV Standard analysis software and analyzed within the stable sessions containing 256 sequential RRi.

RESULTS

The intraclass correlation coefficient (ICC) ranged from 0.942 to 1.000 according to the intrarater analysis by Researcher 01 and 0.915 to 0.998 to the intrarater by Researcher 02. The interrater ICC ranged from 0.921 to 0.998. The coefficient of variation was up to 8.28 for Researcher 01 intrarater analysis, 9.06 for Researcher 02 intrarater analysis and 13.07 for interrater analysis.

CONCLUSION

The measurement of HRV using a portable heart rate device in individuals with COPD present acceptable values of intra- and interrater reliability, supporting the use of HRV in the clinical and scientific scenario. Furthermore, it is important that the data analysis be performed by the same experienced evaluator.

Smart Wearables for Cardiac Autonomic Monitoring in Isolated, Confined and Extreme Environments: A Perspective from Field Research in Antarctica

Antarctica is a space-analog ICE (isolated, cold, and extreme) environment. Cardiovascular and heart autonomic adjustments are key-adaptive physiological responses to Antarctica, both in summer camps and in research stations winter-over. Research fieldwork in ICE environments imposes limitations such as energy restriction, the need for portable and easy-to-handle resources, and resistance of materials to cold and snow/water. Herein, we present the methods we use for cardiac monitoring in the Antarctic field, the limitations of the equipment currently available, and the specific demands for smart wearables to physiological and health tracking in ICE environments, including the increased remote monitoring demand due to COVID-19 restrictions.

Effect of atrioventricular conduction on heart rate variability

This paper discusses the effect of atrioventricular conduction time (AVCT) on the short-term Heart Rate Variability (HRV) by computing HRV parameters using intervals between the onsets of successive P waves (PP time series) for three groups: normal, arrhythmia and sudden cardiac death (SCD) patients. A very precise wavelet transform based ECG delineator was developed to detect PP, PR and RR time series. Mean PR variation in arrhythmia and SCD group was found to be significantly high as compared to the normal group. It was observed that when PR variations in arrhythmia and SCD cases crossed a certain threshold, RR variability no longer provided a very accurate estimate of HRV. In such cases, PP variability was able to provide a better assessment of HRV.

P and R wave detection in complete congenital atrioventricular block

Complete atrioventricular block (type III AVB) is characterized by an absence of P wave transmission to ventricles. This implies that QRS complexes are generated in an autonomous way and are not coordinated with P waves. This work introduces a new algorithm for the detection of P waves for this type of pathology using noninvasive electrocardiographic surface leads. The proposed algorithm is divided into three stages. In the first stage, the R waves located by a QRS detector are used to generate the RR series and time references for the other stages of the algorithm. In the second stage, the ventricular activity (QT segment) is removed by using an adaptive filter that obtains an averaged pattern of the QT segment. In the third stage, a new P wave detector is applied to the residual signal obtained after QT cancellation in order to detect P wave locations and get the PP time series. Eight Holter records from patients with congenital type III AVB were used to verify the proposed algorithm. Although further improvements should be made to improve the algorithm's performance, the results obtained show high average values of sensitivity (90.52%) and positive prediction (90.98%).

Moderate Exercise Induces Different Autonomic Modulations of Sinus and AV Node

BACKGROUND

The routine determination of heart rate variability (HRV) from surface ECGs is based on RR intervals because of the difficulty to precisely locate the P-wave fiducial point on surface ECG recordings. The aim of the study was to assess the changes of RR, PP, and PR intervals at rest and during moderate exercise. The time intervals were determined from atrial and ventricular pacemaker-mediated intracardiac electrograms.

METHODS

Ten patients in sinus rhythm with intrinsic AV node conduction who had received the dual-chamber pacemaker Logos (Biotronik) were included. High-resolution atrial and ventricular intracardiac electrograms were transmitted at rest in supine position and during walking to a portable external recorder. Recording sequences of 150 successive heart cycles were used for HRV analyses after computer-assisted triggering of P and R events. The HRV-index SDNN and power spectral densities for the low (LF; 0.04-0.15 Hz) as well as high (HF; 0.15-0.40 Hz) frequency bands were determined.

RESULTS

SDNN decreased from 26.0 +/- 8.1 ms at rest to 18.3 +/- 4.2 ms during exercise for the PP intervals (P < 0.05) and from 26.8 +/- 8.1 to 18.4 +/- 4.1 ms for the RR intervals (P < 0.05). The LF/HF ratio increased from 2.02 +/- 1.3 to 4.5 +/- 1.5 in the atrium (P < 0.05) and from 2.0 +/- 1.2 to 5.2 +/- 1.9 in the ventricle P < 0.05). Comparing atrial and ventricular HRV at both activity levels, no significant differences were observed for the power of LF and HF spectral components. Regarding the PR intervals SDNN, the total power and the LF/HF ratio did not significantly change during exercise.

CONCLUSIONS

The described technique enabled to record intracardiac electrograms not only at rest, but also during moderate exercise and to use them for HRV evaluation. The changes of PP and RR, but not of the PR intervals, during exercise indicate that autonomic inputs to the sinus node and AV node are independent from each other. The ventricular HRV seems to derive mainly from variations of the sinus node pulse formation.

An Approach to Measure Atrial and Ventricular Heart Rate Variability Using Pacemaker-Mediated Intracardiac Electrograms

Heart rate variability (HRV) measurements are usually performed from ventricular beat-to-beat intervals because of the difficulty to precisely locate the P wave fiducial point in surface ECG recordings. The aim of the study was to describe an approach to determine the atrial and ventricular HRV using pacemaker-mediated intracardiac electrograms. Twelve patients with the dual chamber pacemaker Logos were included. The atrial and ventricular intracardiac electrograms were transmitted with the high resolution telemetry channel of the pacemaker to an external recorder for 20 minutes while the patients were supine. During the measurements the patients were in sinus rhythm with intrinsic AV conduction. After computer assisted triggering of the atrial and ventricular events, the resultant intervals were used to calculate the standard deviation of all NN intervals (SDNN), the square root of the mean squared differences of successive NN intervals (RMSSD), and the percentage of successive interval differences >50 ms (pNN50). The differences between atrial and ventricular HRV-Indexes were assessed for each patient with a cut-off point of 1%. Differences >1% were analyzed in detail. A total of 15,504 heart cycles were analyzed. A manual correction due to false or not triggered atrial or ventricular events was necessary in 0.9%. The overall difference between atrial and ventricular pNN50 was-0.5%+/-2.1%and differences >1% were observed in 4 patients. The NN50 events occurred in the atrial as well as in the related ventricular interval in 84%. NN50 events occurred only in the atrium in 6% and only in the ventricle in 10%. The mean differences between atrial and ventricular SDNN and RMSSD were 0.4+/-2.1 ms and-0.1+/-3.5 ms with intra-individual differences <1%. The present study described a new method and demonstrated its feasibility to determine atrial as well as ventricular HRV from pacemakermediated intracardiac electrograms. The differences for pNN50 indicate that ventricular HRV did not reflect the changes of sinus node activity in all patients.