In regards to the cause of<unk>  a very high percentage are congenital, the right ventricular flow is hindered (or obstructed by this). The cause in turn is divided into: valvular, external and intrinsic (when it is acquired).
Pulmonary valve stenosis
Pulmonary vein stenosis
Tricuspid valve stenosis
Pulmonic stenosis
Supravalvular aortic stenosis
Double inlet left ventricle
Mitral stenosis
Accessory auricle