Unipolar Electrocardiography in Pulmonary Stenosis

Congenital pulmonary stenosis with intact ventricular septum is a relatively common mal- formation of the heart.The stenosis varies from almost complete obliteration to a minimal decrease in the diameter of the orifice.The stenosis is usually of the valve, but it may be either of the infundi- bulum or of the lower bulbar orifice.The atrial septum may be complete, imperfectly developed, or it may be fenestrated: there is often anatomical patency of the foramen ovale, which may or may not allow the passage of blood from the right to the left atrium during life.The pulmonary artery beyond the stenosis is usually dilated and thin-walled, but it may be normal.These variations make for wide diversity in the clinical features of the malformation.It is often a relatively benign lesion, but in its most severe form death occurs within the first year of life (Freed and Budnitz, 1946).Intermediate between these extremes is the group in which infancy is survived and childhood relatively symptomless but, sooner or later, there is increasing exertional dyspncea, with or without cyanosis, leading on to congestive heart failure or sudden death.The work of Brock (1948, 1949) on valvulotomy and infundibular (or lower bulbar) resection has made this latter group of great clinical and diagnostic importance.In spite of the anatomical and clinical variations, the increased work of the right ventricle depends essentially on the severity of the stenosis in relation to the right ventricular output.The extent of the right ventricular hypertrophy is, therefore, an indication of the severity of the lesion, even in the absence of disability, cyanosis, and clinical deterioration.By recording the degree and development of this hypertrophy, unipolar electrocardiography is of great assistance in the assess- ment of the malformation.The purpose of this paper is to demonstrate the characteristic cardiographic pattern of the extreme right ventricular hypertrophy that develops in pulmonary stenosis.The significance of this pattern is discussed in relation to diagnosis, prognosis, and surgical treatment of this congenital defect.ELECTROCARDIOGRAPHIC FEATURES Dow et al. (1950) -have demonstrated by cardiac catheterization that pulmonary stenosis may exist for many years without disability and without electrocardiographic evidence of right ventricular hypertrophy.There may be right bundle branch block (Blackford and Parker, 1941;Auerbach and Harper, 1947), or the cardiographic picture of moderate to marked right ventricular hyper- trophy (Currens, Kinney, and White, 1945;Lowance et al., 1948).Right ventricular preponderance with large, pointed P waves in lead II, a tendency to lengthening of the P-R interval, and frequent inversion of the T waves in leads II and III, have been described by Allanby and Campbell (1949); they also report tall R waves extending across the chest in the three cases in whom they recorded unipolar chest leads.