Myocardial infarction and Antiphospholipid Syndrome: A first study on finger PPG waveforms effects

The aim of this study is to highlight the presence of cardiovascular disease (CVD) using a non-invasive low cost technique: the photoplethysmography (PPG). This work represents a preliminary study in the time domain of finger PPG signals of patients with acute myocardial infarction (AMI), chronic myocardial infarction (CMI), and Antiphospholipid Syndrome (SAA). PPG signals were taken using a commercial pulse oximeter. Twelve PPG waveforms were measured for each studied group (AMI, CMI and SAA) and for a group of healthy volunteers. Time domain PPG signal processing was done using a MATLAB implementation of an improved differential algorithm, in order to detect the characteristic parameter `relative crest time´ (T1/TPT), identified from the literature. The statistical distribution of PPG relative crest time shows that healthy subjects present a relative average crest time below 0.2 and a very tight distribution. On the contrary, patients with AMI, CMI and SAA have a higher mean value of T1/TPT and a wide asymmetrical shape of distribution. The obtained results suggest that a T1/TPT value above the 0.2 threshold is dangerous for healthy subjects. Moreover, the results extracted from PPG signal of younger patients with SAA seem particularly significant.