Cardiovascular diseases (CVDs) are dysfunction

 Cardiovascular diseases (CVDs) are dysfunctions of the heart and blood vessels and include hypertension or high blood pressure (BP), cardiac arrhythmia, cardiac ischemia, and stroke. CVD is the primary cause of universal death and the leading cause of damage to arteries in organs such as the heart, brain, eyes, and kidneys [1]. BP is a vital physiological sign of the human body that can be varying over time due to physical condition, physiological rhythm, environmental conditions, and so many other factors [2]. 

Monitoring the long-term continuous changes of BP can significantly increase the ability of clinicians to manage the evaluation of arterial alterations and determine CVD risk. Moreover, the continuous BP measurement gives the chances of early diagnosis and clinical treatments of cardiovascular patients through home-based or clinically measurement Food gloves. 

The most accurate and clinically accepted continuous BP measurement methods mostly include arterial tonometry tension and volume compensation parameters, and pulse wave velocity (PWV) parameters. The arterial tonometry method applies to the radial artery that does not need calibration and can be considered as an accurate measurement for long-time monitoring, however, the utilized sensor could be susceptible to artifacts [3]. The BP monitoring devices using the volume compensation method required a reference pressure setting and regular calibration, which increases the complexity of the measurement technique Synthetic Gloves. 

Moreover, the continuous pressure in venous congestion will cost significant pain for the patients [4]. The relationship between blood pressure and PWV was first theoretically validated by Moens and Korteweg (M-K) [5]. The PWV method achieved a more straightforward design for BP measuring devices and solved the somberness of patient’s comfortability in long-term monitoring.

 Concerning using PWV technique, in recent year, the researchers have extracted more features based on time and frequency domain from PWV signals to accomplish multivariate regression models [6, 7]. The pulse transit time (PTT) is one of the features that has shown a high correlation with BP [8]. PTT is related to PWV, and both of them show a relationship with BP [8] inversely. The PTT can be defined as the time takes for an artery pulse to propagate between two arterial sites. 

The definition of PTT can be shortened as the time difference between the R-wave peak in the electrocardiogram (ECG) and the specific point in photoplethysmogram (PPG) signals. Although there have been a considerable number of promising researches based on the relationship of blood pressure with PTT over the past 15 years [9–12], many problems remain for widespread clinical use of this method YICHANG.