Yoshihisa Nagata

Electrocardiographic changes in pulmonary emphysema: Effects of experimentally induced over-inflation of the lungs on QRS complexes

Summary Seventeen dogs were anesthetized with sodium pentobarbital. In these dogs, over-inflation of the lungs was experimentally induced by blocking the exhaust of a respirator. Dislocation of the heart during over-inflation of the lungs was prevented by fixing the heart on a supporting rod. Three pairs of bipolar electrodes were implanted either on the anterior or posterior wall of the ventricles. They were used as the X- (left-to-right), Y- (foot-to-head), and Z- (front-to-back) dipoles while passing alternating currents (50 μA, 20 Hz.). The electrical signals generated from these dipoles were recorded with the McFee-Parungao lead system. The same lead system was used for recording electrocardiograms. The effects of the over-inflation of the lungs upon the potentials generated from the dipoles and upon the QRS complexes of the electrocardiograms were investigated. Potentials generated from the X-dipole on the anterior or posterior wall decreased during over-inflation of the lungs, in parallel with the R wave in Lead X. Similar reduction was found between the potentials generated from the Y-dipole on the anterior or posterior wall and the R wave in Lead Y. In contrast, opposite changes were found between the potentials generated from the Z-dipole on the anterior or posterior wall. There was a decrease of the potential generated from the Z-dipole on the anterior wall and an increase of that from the Z-dipole on the posterior wall. Similar contradictory changes were found between the R and S waves in Lead Z. The parallelism between changes in the potentials generated from the dipoles and the R and S waves of three orthogonal leads was found to be statistically significant (correlation coefficients ≥ 0.80. Since the position of the heart was fixed, the changes in the potentials generated from the dipoles induced by over-inflation of the lungs could be attributed to the increased electrical resistance of the lungs. The same explanation may be applied to those changes in the R and S waves which were closely related to the changes in the potentials generated from the dipoles. On the basis of resemblance of the changes in the QRS complexes between pulmonary emphysema and the experimentally induced over-inflation of the lungs, increased resistance of the lungs may contribute to changes in QRS complexes in pulmonary emphysema.