Management of primary pulmonary hypertension

Management of primary pulmonary hypertension

Primary pulmonary hypertension is a condition with a guarded prognosis and most often a limited survival. Various agents have been tried in the management of primary pulmonary hypertension, with limited efficacy. Anticoagulants have been used for a long time and should be maintained at therapeutic INR (international normalized ratio) levels of prothrombin time to document effective dosing. Digoxin, diuretics and oxygen supplementation have a role in those with heart failure. Calcium channel blockers have been used in fairly high doses for the treatment of primary pulmonary hypertension. Nifedipine and diltiazem are the two important agents, with latter being preferred when the heart rate is on the higher side, due to the response of nifedipine producing reflex tachycardia and diltiazem producing bradycardia. Ideally a response to vasodilators have to be documented before starting these, with epoprostenol or nitric oxide. Calcium channel blockers are not to be given if there are features of right ventricular dysfunction or failure as these agents have negative inotropic effects which can worsen the ventricular dysfunction.

Prostacyclin analogues like epoprostenol which is given intravenously, treprostinil which may be given intravenously, subcutaneously and iloprost which is given by nebulization are other agents found useful in the management of primary pulmonary hypertension.

Oral phosphodiesterase 5 (PDE5) inhibitors like sildenafil and tadalafil also have beneficial effects in primary pulmonary hypertension. The latest addition to the therapeutic armamentarium are oral endothelin antagonists bosentan, macitentan and ambrisentan. Endothelin receptor involved is ET1 which has two subtypes: ET_A and ET_B. Ambrisentan is an ET_A antagonist while macitentan is a dual receptor blocker with more affinity for ET_A.  ET_A is involved in vasoconstriction and proliferation while the role of is ET_B vasodilatation and ET1 clearance [1].

Reference

1. Michele Correale, Armando Ferraretti, Ilenia Monaco, Davide Grazioli, Matteo Di Biase, Natale Daniele Brunetti. Endothelin-receptor antagonists in the management of pulmonary arterial hypertension: where do we stand? Vasc Health Risk Manag. 2018 Oct 4;14:253-264.