Primary and secondary pulmonary hypertension

Abstract

Pulmonary hypertension (PH) is a complex syndrome that may complicate different cardiovascular, respiratory and systemic disorders. Once considered an orphan disease, currently things have changed in recent years due to major progress seen towards the understanding of this multidisciplinary disorder. PH is defined as an increase in mean pulmonary artery pressure (PAP) ≥25 mmHg at rest as measured invasively by right heart catheterization (RHC). According to common pathophysiological and therapeutic characteristics, 5 clinical groups of PH are defined. Pulmonary arterial hypertension (PAH) or group 1 of PH includes idiopathic and heritable PAH, PAH associated with connective tissue disorders, congenital heart diseases, toxins and drugs, HIV infection and portal hypertension. The common feature of these PH forms is involvement of the distal pulmonary arteries. In PH, the right ventricle (RV) adapts to a dual pressure overload composed by the fixed pulmonary vascular resistance and the pulsatile pressure overload due to pulmonary artery stiffness. RV function is the main determinant of the outcome in PH patients. Based on clinical suspicion or screening of high risk populations, transthoracic echocardiography establishes the probability of PH while the RHC is mandatory to confirm the diagnosis, to assess the severity of haemodynamic impairment and to perform pulmonary vasoreactivity testing in selected PAH patients and to assess the response to PAH treatment or confirm disease worsening. Other diagnostic tools are useful to identify the different forms of PAH and PH and to test the exercise capacity of the patients. Treatment of PAH has evolved considerably over the past 30 years, in part due to the advances in knowledge of the disease and the availability of drugs that target known pathways in the disease pathobiology. Despite this real progress, PAH remains a chronic progressive disorder. Current therapeutic approaches are medical therapy, interventional and surgical procedures.