Characteristics of Circadian Blood Pressure Pattern of Hypertensive Patients According to Localization of Fragmented QRS on Electrocardiography

Electrocardiographic alterations in patients with chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiovascular events, and electrocardiography has an important role in detecting cardiac side effects of COPD-related hypoxia.

Hidden Markov model-based heartbeat detector using electrocardiogram and arterial pressure signals

The automatic detection of a heartbeat is commonly performed by detecting the QRS complex in the electrocardiogram (ECG), however, various noise sources and missing data can jeopardize the reliability of the ECG. Therefore, there is a growing interest in combining the information from many physiological signals to accurately detect heartbeats. To this end, hidden Markov models (HMMs) are used in this work to jointly exploit the information from ECG, arterial blood pressure (ABP) and pulmonary arterial pressure (PAP) signals in order to conceive a heartbeat detector. After preprocessing the physiological signals, a sliding window is used to extract an observation sequence to be passed through two HMMs (previously trained on a training dataset) in order to obtain the log-likelihoods of observation and signals a detection if the difference of log-likelihoods exceeds an adaptive threshold. Several HMM-based heartbeat detectors were conceived to exploit the information from the ECG, ABP and PAP signals from the MIT-BIH Arrhythmia, PhysioNet Computing in Cardiology Challenge 2014, and MGH/MF Waveform databases. A grid search methodology was used to optimize the duration of the observation sequence and a multiplicative factor to form the adaptive threshold. Using the optimal parameters found on a training database through 10-fold cross-validation, sensitivity and positive predictivity above 99% were obtained on the MIT-BIH Arrhythmia and PhysioNet Computing in Cardiology Challenge 2014 databases, while they are above 95% in the MGH/MF waveform database using ECG and ABP signals. Our detector approach showed detection performances comparable with the literature in the three databases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13534-021-00192-x.

Electrocardiographic differences in patients with true and pseudo-resistant hypertension

Cardiovascular disease is the leading cause of mortality in hypertensives, and patients with true resistant hypertension have an increased risk for premature cardiovascular events. Electrocardiography (ECG) has an essential role in the monitoring of hypertensive heart disease; however, little is known about the importance of ECG parameters in patients with resistant hypertension. We aimed to investigate whether fragmented QRS (fQRS) and frontal plane QRS-T angle, which are novel ECG parameters indicating myocardial damage, predict true resistant hypertension in patients with uncontrolled blood pressure. Four hundred six hypertensive patients with resistant hypertension were prospectively enrolled for the study. Patients were divided into two groups as 'true resistant' or 'pseudo-resistant' hypertensives and compared regarding the ECG parameters. While 73 (18%) patients had true resistant hypertension, 333 (82%) patients had pseudo-resistant hypertension. The frequency of fQRS (47.9% vs. 20.1%, p < 0.001) and average frontal plane QRS-T angle (93.0° ± 19.7° vs. 53.8° ± 10.2°, p < 0.001) were significantly higher in patients with true resistant hypertension compared to those with pseudo-resistant hypertension. Also, fQRS in anterior leads was significantly more frequent in patients with true resistant hypertension (57.1% vs. 23.8%, p < 0.001). Moreover, ROC curve analysis demonstrated that an increased frontal plane QRS-T angle > 90.75° predicted true resistant hypertension with a sensitivity 96% and specificity 61% (AUC:0.874, p < 0.001). Furthermore, multivariate analysis demonstrated that fQRS in anterior leads (OR: 1.251, 95% CI: 1.174-1.778, p = 0.002) and frontal plane QRS-T angle (OR: 1.388, 95% CI: 1.073-1.912, p < 0.001) were independent predictors of true resistant hypertension. In conclusion, fQRS and frontal plane QRS-T angle may be useful to predict true resistant hypertension in patients with uncontrolled blood pressure.