An electrocardiography (ECG) synchronization technique allowed triggering of 1.5-T echo-planar acquisitions of the heart, with high gradient slew rates. In 51 volunteers (37 men and 14 women, aged 21-48 years), the ECG signal was amplified, filtered, and converted into an optical signal directly above the heart and was transmitted optically outside the bore. Reliable and artifact-free ECG tracings were obtained in all cases, regardless of the gradient switching speed.