The usefulness of routine electrocardiographic monitoring in the EEG laboratory.

In two groups of 500 unselected general hospital patients, EKG abnormalities were found in the EEG lab in 7% and 18.6%. While the most common abnormality was premature ventricular contractions, a wide variety of serious and minor abnormalities were seen, in some instances of emergent nature. Cardiac disease was unsuspected in around 40% of these patients and confirmed in a majority of these when looked for. Depending on the EKG abnormality, hyperventilation was shown to have an adverse effect 9--50% of the time in patients with normal EKG's, it tended to produce an increase of heart rate, but this was not invariant and the change in heart rate was not related to air exchange or EEG change. It is easy for any EEG laboratory to record EKG with existing equipment, and the results of this study suggest that it should be incorporated as a routine procedure. Moreover, the data indicated that hyperventilation is not necessarily a benign procedure. It should be undertaken only after control EKG recordings and assessment of the patient's cardiac status, and performed with EKG monitoring.