An ECG synchronization circuit for real-time infrared imaging of epicardial coronary vessels

Trigger circuitry designed to synchronize a real-time infrared (IR) imager with the electrocardiogram (ECG) is presented. This synchronization (SYNC) circuit enables the IR imager to acquire a sequence of images at a fixed point in the cardiac cycle, a capability essential for measurement of epicardial coronary vessel diameter. The P wave was used as a trigger signal to test the performance of the SYNC circuit. However, other electrical signals, such as the R wave or aortic BP signals, can be chosen as trigger signals. As an extension to this circuit, a timer can be used to delay the output signal of the SYNC circuit to capture images a few milliseconds after the trigger signal