a2>p2, the second heart sound in the aortic valve auscultation area is greater than the second heart sound in the pulmonary valve auscultation area. Under normal circumstances, a2 is heard most clearly in the aortic valve auscultation area, with a high tone and metallic sound, while p2 is heard most clearly in the pulmonary valve auscultation area with a low tone. a2 < p2 in adolescents; in adulthood, a2 = p2; in the elderly, a2 > p2. When the resistance of the body circulation increases or blood flow increases, such as hypertension and coronary arteriosclerosis, the aortic valve pressure increases and a2 hyperactivity occurs, with a2 > p2. When the resistance of pulmonary circulation is increased or blood flow is increased, such as pulmonary heart disease, pulmonary hypertension, atrial septal defect, arteriovenous catheterization p2 hyperactivity, a2 < p2. a2 > p2 or p2 > a2 are found clinically, further electrocardiogram, cardiac ultrasound should be examined to initially screen for pathological causes.