Programming and testing of a small-size ECG monitor for small animal gated imaging

Abstract

Pre-clinical cardiac imaging has become one of the most important non-invasive techniques widely used nowadays for studying the electrophysiology and hemodynamic behaviour of the heart using small animals’ models. Despite the great potential it offers for clinical applications in humans, the introduction of movement artefacts and blurring in the images due to the inherent blood flow and respiration among others, reduces significantly the quality of imaging leading to mistakes in results interpretation. A solution to this problem is the synchronization of the electrocardiogram with the imaging machine in a process called gated imaging to trigger image acquisition at specific moments of the cardiac cycle. In this manner, the principal objective of the presented Bachelor Thesis was to design, develop, program and test a small size ECG monitor for small animal gated imaging. The main functions of this device are monitoring the cardiac activity at the same time a TTL pulse is activated in real-time for gating synchronization with the imaging machine. A microcontroller, an analog-to-digital converter and a touch screen were connected together to form a small ECG device that is able to record bioelectrical signals of the heart, to process them and display the electrocardiogram on the screen and generate a TTL pulse for gated imaging. Communication in between the different modules was enabled by SPI protocol implementation. The evaluation of the ECG prototype was performed first in the laboratory with an ECG simulator showing good performance to be later tried in small animals. On the whole the results were satisfactory except from some issues in TTL pulse activation that might need further improvements to enhance gated imaging implementation. This project and the future improved versions of this ECG device, will have a big scientific and social impact. This small size ECG monitor will not only offer an easy to use portable monitoring device for pre-clinical research but also a powerful tool for gated imaging that will be essential for the development of revolutionary drugs to treat heart diseases.