Stockwell Transform Based Time-Frequency Analysis of the ECG Features for Assessment of Risk of Left Ventricular Hypertrophy in Hypertension Patients

Hypertension is a major disease that affects millions of people world-wide. If hypertension remains untreated for long time it could give rise to an enlarged heart condition called Left Ventricular Hypertrophy (LVH). However, recent research in medical domain proposes that left ventricular diastolic dysfunction (LVDD) may be considered as a preceding indicator of LVH. The analysis of ECG signal has shown significant results in identifying LVDD condition that can lead to LVH, however the analysis method till date have remain limited to the manual examination of time domain features of ECG parameters by the experts which is time consuming and cumbersome. Since the time-frequency analysis of the ECG signal have shown more promising results in diagnosis of any abnormality related to the cardiac system, therefore the application of this method is employed in the patients suffering from hypertension and for assessment of the future risk(s) in developing LVH. In the study, we have proposed a Stockwell Transform based time-frequency analysis method of the ECG features (QRS Complex, P-Wave and T-Wave) for accessing the preceding stage of the myocardial remodeling phase. To perform the study, ECG features of the 60 subjects recorded from hospital comprising of 30 controlled and 30 hypertension cases were studied. At the location of the QRS interval a spreading in the power is observed in diseased patients, which signifies increased ventricular activation time, also the power level of the P-Wave and T-Wave have shown significant changes. Increased Ventricular activation time and P-Wave dispersion observed in the frequency domain along with P-wave terminal force, can be used as an indicator of associated risk of developing Left Ventricular Hypertrophy.