Stenosis can be of three varieties according to the level of damage. Valvular stenosis directly affects the leaflets, which become thin; in this case, the adhesions partially grow together, and the ring, i.e. directly the border of the hole that closes the valve is underdeveloped. Supravalvular stenosis is otherwise called peripheral and is a variant of narrowing of the pulmonary artery. Subvalvular, or subvavular, stenosis is a defect that significantly reduces the patency of the outflow tract of the right ventricle.