Desenvolvimento de um fonocardiógrafo digital utilizando ESP32

Abstract

Cardiovascular diseases are among the leading causes of death in Brazil and worldwide. Among heart diseases, valvular diseases stand out, which have gained more attention with the increase in life expectancy of the population. One way to identify valvular diseases is through cardiac auscultation using a stethoscope, a technique whose accuracy can vary depending on the professional’s experience. This work aimed to develop a prototype of a digital phonocardiograph to assist in the auscultation process with visual representations. For this purpose, stages of cardiac signal acquisition, amplification, and conditioning were designed and implemented, with the signal being sent to an ESP32 microcontroller. In this device, the analog signal is converted into a digital signal, processed through a digital filter, and displayed on the M5Stack Core2 module’s display. Signal acquisition is performed using an electret microphone, followed by amplification due to the low signal amplitude, and filtering, consisting of a low-pass and a high-pass filter, to eliminate noise and isolate the frequency range of heart sounds. The ESP32 applies a moving average filter to provide a more accurate display on the M5Stack Core2 display, which also powers the circuit. Simulations and tests were conducted to validate the prototype, revealing some limitations due to the graphical resolution of the M5Stack Core2 display. However, there was successful integration of hardware and firmware, with the signal being displayed in a manner similar to examples found in the literature, achieving the proposed objectives.