- Hypertrophy is a thickening of the ventricular wall, while dilation is an enlargement of a chamber to accommodate increased blood volume. Enlargement affects the atria, while hypertrophy affects the ventricles. - The P wave is used to identify atrial enlargement, while changes in the QRS complex indicate ventricular hypertrophy. Increased duration, amplitude or axis deviation serve as indicators. - Right atrial enlargement increases the first part of the P wave amplitude. Left atrial enlargement increases the terminal P wave amplitude in V1 and the P wave duration.