The effect of heart orientation on high frequency QRS components in multiple bandwidths

Reduced power of high frequency (HF) oscillations inside the QRS complex reflects ischemic pathology in the heart. In order to show spatial and frequency dependencies, we examined the effect of heart orientation on power of high frequency components under normal and ischemia condition within various frequency bands. Root mean square (RMS) of the signal in QRS region within frequency bands from 150 Hz to 550 Hz and heart rotation around longitudinal axes (360°) were computed from four rabbit isolated hearts. Experimental protocol included control, ischemic and reperfusion phases. This pilot study shows that RMS level of HF signal in non-ischemic heart differs within lead orientation and its maximum lies in a region around specific angle. Relative decrease in RMS value also depends on lead position. When depicted in spatial-frequency plane with polar coordinates, these relative changes contributes to specific patterns under both normal and ischemic conditions, which should be further examined.