PHOTOPLETHYSMOGRAPHY(PPG) for Cardiovascular Disease 

Edited by, SNEHA MAVIS 

Photoplethysmography (PPG) is a non-invasive optical technique for measuring and detecting changes in blood volume in peripheral blood vessels, such as the ear lobes, fingers and toes. The process usually involves using light to illuminate the skin and taking measurements from the skin's surface. Changes in blood volume produced by pressure can be detected by illuminating infrared or photodiode light on the skin.

According to the European Society of Cardiology (ESC), heart rate is an independent risk factor for cardiovascular disorders; as a result, any change in normal heart rate (or blood volume) activity is a significant indication for cardiovascular dysfunction. Photoplethysmography, which focuses on blood volume consistency and monitoring, has made it easier for doctors to screen, detect and monitor the presence of cardiovascular diseases.

For each heartbeat, a Photoplethysmography would normally measure the pulse cycle duration(T), digital volume pulse(DVP), augmentation Intex(AIx), transit time of reflected wave(RTT) and reflection index(RI). Photoplethysmography generally measures blood pressure, oxygen saturation and cardiac output using a wave and peak detection.

As the complex arterial system is made up of branching elastic tubes through which pulsed blood from the heart passes, any fatty deposits that form a blockage would allow pressure to build up and hinder normal blood flow in the problem area. Abnormal light illuminations in the PPG process would reveal this activity.

Physicians and medical practitioners have recognized the benefits of using Photoplethysmography over typical screening methods such as electrocardiograms(ECG). Photoplethysmography, as a less expensive and the easier technology, enables for the easy detection and monitoring of cardiac problems without the need for invasive procedures.