Pseudo-QT prolongation, artifactual electrocardiographic patterns produced by transduction of cardiovascular motion

Four cases are presented in which focal electrocardiographic artifacts mimicked QT segment prolongation with giant T and U waves. Displacement of the recording electrode by a subjacent cardiovascular impulse was the cause of this distortion. The artifacts could be reproduced at the bedside by intentional changes in patient posture and electrode stability. Phasic variation in electrode contact with the electrolyte gel and skin, or intermittent contact between the heart and chest wall, causes shifts in the electrical properties of the recording system which may distort the recorded waveforms during the repolarization phase of the electrocardiogram.