Secondary Pulmonary Hypertension

The diagnosis of pulmonary hypertension first requires a clinical suspicion, as symptoms are often nonspecific. After the diagnosis is made, appropriate classification into the various categories of pulmonary hypertension is essential in order to manage the patient's disease and symptoms appropriately. Therapy is targeted at the underlying cause of the pulmonary hypertension, as well as its effects on the cardiovascular system. Until recently, the treatment of both primary and secondary pulmonary arterial hypertension was limited to supportive therapy alone. With the advent of novel therapeutic agents, more focused therapies designed to treat the pulmonary vasculopathy have become available. These include pulmonary vasodilators such as continuous intravenous prostacyclin, and experimental agents currently undergoing clinical trials. For patients with pulmonary hypertension secondary to pulmonary venous hypertension, therapies differ. In cases where there is left-sided heart disease leading to pulmonary venous hypertension, treatment is aimed at repairing or ameliorating the underlying heart disease. Patients with pulmonary venous hypertension due to extrinsic compression of the central pulmonary veins, or pulmonary veno-occlusive disease have few options, and treatment is generally palliative. In patients with pulmonary hypertension that is associated with disorders of the respiratory system or hypoxemia, the pulmonary hypertension is due to a reactive pulmonary vasoconstriction. Reversal of this vasoconstriction with pulmonary vasodilators can be harmful because of the risk of increasing perfusion to nonventilated lung units. Pulmonary hypertension due to chronic thrombotic or embolic disease can be treated surgically, if the obstructive thrombi are proximal enough for the surgeon to resect them. More distal pulmonary emboli, however, cannot be resected, but there is emerging evidence that the chronic administration of pulmonary vasodilators can be effective in treating this form of the disease.