Correlation between the shape of the P wave and the length of the P-R interval in normal electrocardiograms

Abstract 1. 1. P waves may exhibit different shapes, sizes, and, also, correlations. 2. 2. Peaked P waves are, on an average, taller and of shorter duration than rounded P waves. They are associated with a short P-R interval and are found in younger age-groups. Rounded P waves are found with greater frequency in the older age-groups and are associated with a prolonged P-R interval. 3. 3. Notched P waves behave as rounded atrial waves. 4. 4. Correlations between the shape of the P wave and the length of the P-R interval are explained by the intervention of autonomic nerves, especially by differences in the vagal tone.