Secondary pulmonary hypertension: a review of the cardiac causes

Pulmonary hypertension (PAH) is defined as mean pulmonary artery pressure greater than 25 mm Hg at rest, or greater than 30 mm Hg with exercise. While there are a myriad of etiologies for PAH, many times a cardiac etiology may be present. This is particularly important from both diagnostic and therapeutic standpoints, as many lesions are readily repairable with corrective surgery. Often, PAH may be drastically reduced, or even returned to baseline, after surgical correction. This article focuses on these cardiac etiologies of secondary PAH. Primary PAH, and PAH secondary to disease of the lung parenchyma, will not be discussed. Pulmonary hypertension is generated by increased flow through the pulmonary arteries, increased resistance to flow, or venous obstruction at the entrance to the left atrium. There is no upper limit of PAH that definitively precludes surgery, thus all patients with surgically approachable lesions should be referred for evaluation.