Cardiovascular response and seizure duration as determined by electroencephalography during unilateral electroconvulsive therapy.

The effect of pulse unilateral electroconvulsive therapy (ECT) on heart rate, blood pressure and the product of heart rate and systolic blood pressure, an index of myocardial oxygen consumption, was studied during 48 ECT sessions in 7 patients with major depression. Intra-individually, hyperventilation-induced hypocapnia compared with normocapnia markedly augmented the ECT-induced increase in heart rate (47% vs 28%) and the product of heart rate and systolic blood pressure (82% vs 60%). Over all ECT seizures, the maximum and increase in heart rate and the product of heart rate and systolic blood pressure were significantly correlated with seizure duration as determined by electroencephalography. However, significant correlations were only present for the seizures during hypocapnia and not during normocapnia. Combining measures of magnitude and length of ECT-induced tachycardia to motor responses may increase the potential for clinical seizure evaluation.