The clinical significance of right axis deviation in the electrocardiogram

Abstract

1. 1. We have made a clinical analysis of 200 cases in which the electrocardiogram showed right axis deviation of more than +90°, excluding those with low voltage of the QRS complexes and intraventricular or bundle branch block. The most common findings were mitral stenosis, in 44.5 per cent of the cases, and no heart disease, in 37.5 per cent, leaving only 18 per cent associated with other conditions. Congenital heart disease was the third most common finding, responsible for 7 per cent of the cases. 2. 2. The upper normal limit of right axis deviation we found to be +109°, except for 3 cases. We believe, therefore, that axis deviation of +110°, or more, practically always indicates organic heart disease. 3. 3. Of the 200 cases of right axis deviation, coronary heart disease was found in only 7 (3.5 per cent), and in only one was it of more than slight degree. The position of the heart in the chest, rather than right ventricular strain, probably accounts for this combination. In view of the fact that the incidence of coronary heart disease is high among patients whose electrocardiograms are made in this laboratory, it is evident that the finding of right axis deviation electrocardiographically is strong, though not conclusive, evidence that the patient does not have coronary heart disease. In such cases cor pulmonale, partienlarly, should be considered. 4. 4. An analysis of the electrocardiogram with regard to axis deviation in cases of cor pulmonale and of the most common types of congenital cardiac defects (tetralogy of Fallot, interventricular septal defect, and patent ductus arteriosus) led to the following conclusions: (1) the tetralogy of Fallot always causes right axis deviation, usually of a high degree, except when there is an associated congenital dextrocardia; (2) interventricular septal defect rarely causes any deviation of the electrical axis, and if it does, the tendency is for right axis deviation to occur; (3) patency of the ductus arteriosus almost never causes right axis deviation, but may cause significant left axis deviation; and (4) in cor pulmonale there is always right axis deviation (or a tendency to right axis deviation), although not necessarily of high degree. 5. 5. We believe that even a slight degree of right axis deviation may be very significant and that its proper evaluation can be of prime importance in leading to a correct clinical diagnosis. In the normal person a vertical position of the heart in the chest or its rotation to the left around its longitudinal axis by a thoracic or spinal deformity is the most important factor leading to right axis deviation; while in the case of a transverse or enlarged heart, right axis deviation is almost always due to a cardiac defect which has led, either primarily or secondarily, to right ventricular strain.