Cardiac potentials in pulmonary disease. Overdistension of the lung versus cor pulmonale (right ventricular hypertrophy)^*

These studies demonstrated the distribution of cardiac potentials on the body surface in children with clinical evidence of overdistension of the lungs without right ventricular hypertrophy. The effect of the overdistended lung was shown to alter body surface events during ventricular activation by causing an inferior shift of potential maxima and minima during the middle third of the QRS. Roentgenographic studies demonstrated an associated inferior shift of the heart in relation to the anterior chest surface. Further shown was the associated diminished values of potentials over the left lateral chest during this interval in the patients with cystic fibrosis, as compared to normal children. The results of surface-mapping and x-ray studies indicated that leads placed in the fourth interspace monitor different body surface events during the middle of QRS in the cystic fibrosis children as compared to normal children due, in large part, to the inferior shift of potential maxima and minima. In the presence of cor pulmonale with marked right ventricular hypertrophy the potential distribution over the body was quite different in normal subjects and in those with cystic fibrosis. Right ventricular hypertrophy produced a migration of the anterior maximum in a rightward direction during the latter part of the QRS. Its terminal position was located beneath the right clavicle. These events differed from those in normal subjects and those with cystic fibrosis who showed a leftward migration of the maximum with a terminal distribution characterized by anterior minimum and posterior maximum.