Blood Pressure Variability in Clinical Practice: Past, Present and the Future

Abstract

Recent advances in wearable technology through convenient and cuffless systems will enable continuous, noninvasive monitoring of blood pressure (BP), heart rate, and heart rhythm on both longitudinal 24-hour measurement scales and high-frequency beat-to-beat BP variability and synchronous heart rate variability and changes in underlying heart rhythm. Clinically, BP variability is classified into 4 main types on the basis of the duration of monitoring time: very-short-term (beat to beat), short-term (within 24 hours), medium-term (within days), and long-term (over months and years). BP variability is a strong risk factor for cardiovascular diseases, chronic kidney disease, cognitive decline, and mental illness. The diagnostic and therapeutic value of measuring and controlling BP variability may offer critical targets in addition to lowering mean BP in hypertensive populations.

Keywords: blood pressure; blood pressure variability; digital cardiovascular health; hypertension; noninvasive blood pressure monitoring; photoplethysmography; smart wearable devices.

Figure 1. Determinant of blood pressure.

PWV indicates pulse wave velocity.

Figure 2. Potential mechanism of impact of blood pressure variability (BPV) on microcirculation and target organ damage.

CRP indicates C‐reactive protein; ED, endothelial dysfunction; IL‐6, interleukin‐6; TNF‐alpha, tumor necrosis factor‐alpha; and VSMC, vascular smooth muscle cell.

Figure 3. Methods for measurement of blood pressure variability.

BP indicates blood pressure; HR heart rate; and HRV, heart rate variability.

Figure 4. Principle of photoplethysmography (PPG).

Data generated from volumetric blood flow changes due to light passing through the fingertip into the RBG sensor (red, blue, and green light sensor). The raw PPG data is fed into a machine learning algorithm for PPG feature extractions. BP indicates blood pressure.