Background: Congenital cardiac disease with increased pulmonary blood flow or increased pulmonary venous pressure is frequently accompanied by the development of pulmonary hypertension and its accompanying enhanced the vascular reactivity. Breathlessness with worsening exercise tolerance is linked to the development of pulmonary arterial hypertension in congenital heart disease. The most prevalent symptom of pulmonary arterial hypertension and congenital heart disease (CHD) is dyspnea development, which was formerly believed to be brought on by deteriorating PAH but may also be brought on by inflammation and abnormalities in lung function. A sensitive non-invasive marker for vascular alterations in children with congestive heart failure is endothelin-1. Conclusion: Numerous investigations have suggested that the pulmonary vascular endothelium produces the 21-amino acid vasoactive polypeptide known as endothelin-1 (ET-1), which has strong vasoconstrictor effects and promotes the growth of vascular smooth muscle cells. The early vascular change diagnosis reduces comorbidities and enables early medical management and/or surgical repair.