High frequency ECG-a new method to examine depolarization changes mediated by transient myocardial ischemia

The very-high-frequency components (150-250 Hz) of the electrocardiogram were evaluated. Experiments were designed to determine the extent to which the morphology of the high-frequency QRS potentials is affected by transient myocardial ischemia. The high-frequency ECG was studied in dogs during induced ischemia and in patients undergoing angioplasty. It was found that the high-frequency ECG appears to detect evidence of transient ischemia with greater sensitivity than visual inspection of the surface ECG and may therefore provide useful information. A finite-element three-dimensional model with a self-similar (fractal) conduction system was introduced as a bridge to the understanding of these electrocardiographic phenomena. By using this model it was found that the morphological changes in the high-frequency QRS can be attributed to a slowing of conduction velocity in the region of ischemia