SEARCH Articles Figures Tables R amplitude in lead V3 S amplitude in lead V3 by age, each curve corresponding to the indicated percentile level . The sum of R wave amplitude in lead V3 and S wave amplitude in V3 deaeases slightly after birth. It increases after age 7-30 days, reaching the highest value at ages 3-6 months and 1 -3 years, then decreases thereafter up to age 13-18 years. [Publishers Imprint]