The Electrocardiogram and Vectorcardiogram in Right Ventricular Hypertrophy and Right Bundle Branch Block

Abstract

It is the purpose of this paper to appraise certain applications of the electrocardiogram and vectorcardiogram to the diagnosis of right ventricular hypertrophy. The problems that are encountered in this area of electrocardiography are created by the similarity of the records seen in recognizable right ventricular hypertrophy to those that occur in normal infants and to those that are seen in right bundle branch block. The not infrequent failure of any kind of record of the cardiac potentials to reveal recognizable evidence of right ventricular hypertrophy when in fact it is proved to exist adds further confusion to this constellation of difficulties. For the purpose of this paper it has been deemed practical to ignore almost completely problems created by the coexistence of left ventricular hypertrophy and other conditions occurring frequently in rheumatic heart disease (which contribute to the difficulties that are encountered in this area of electrocardiography and vectorcardiography). Our material consists of 1) serial observations on a large group of normal infants some of whom are now five years of age; 2) observations of individuals with congenital heart disease; 3) observations of normal young adults; and 4) observations on an individual with varying degrees of right bundle branch block. In addition we have reviewed observations of other authors that fall in the first three of the above categories. At the outset it is necessary to clarify certain matters that frequently appear to become confused in the literature. In the individual case entirely satisfactory proof of the presence of right ventricular hypertrophy can be obtained only at autopsy. The inference that the right ventricle is hypertrophied when the intraventricular pressure is high and more especially, the inference that it is not hypertrophied when the intraventricular pressure is normal, must be rejected because of the lack of close correlation between the level of the intraventricular pressure and the degree of hypertrophy found at autopsy in individual cases. On the other hand, when one encounters a large group of cases of the same cardiac condition in which a characteristic electrocardiogram is observed, it is not illogical to relate the electrocardiographic findings in question to the presence of that condition. However, the mechanism by which the cardiac condition produces the characteristic electrocardiographic changes may still be open to question. The form of the electrocardiogram may depend upon alterations of the cardiac potentials due to such a structural change as right ventricular hypertrophy or, on the other hand, it may result from a func