Vectorcardiogram with McFee-Parungao lead system in spontaneously hypertensive rats.

Vectorcardiograms (VCG) were recorded from five spontaneously hypertensive rats (SHR) and five age-matched normal wistar rats (WR). Arterial systolic blood pressure was 115 +/- 10.8 mmHg in WR and 176 +/- 7.7 mmHg in SHR. The basic procedures for recording VCG in the rat were investigated. After rats were anesthetized with urethane-chloralose, VCG were taken by using the McFee-Parungao lead system in restrained ventral position. VCG in SHR were characterized by superior, posterior and leftward shift of QRS loops, a more elliptical form of QRS loops in the horizontal plane, and an increase in QRS-T angles in all planes, when compared with WR. These vectorcardiographic findings in SHR were quite similar to those produced by left ventricular hypertrophy in humans.