**3. Etiology**

1.5 Persistent pulmonary hypertension of the newborn

2. Pulmonary hypertension owing to left heart disease

3.1. Chronic obstructive pulmonary disease

3. Pulmonary hypertension owing to lung diseases and/or hypoxia

4. Chronic thromboembolic pulmonary hypertension (CTEPH) 5. Pulmonary hypertension with unclear multifactorial mechanisms 5.1. Hematologic disorders: myeloproliferative disorders, splenectomy

3.3. Other pulmonary diseases with mixed restrictive and obstructive pattern

2.1. Systolic dysfunction 2.2. Diastolic dysfunction 2.3. Valvular disease

2 Pulmonary Hypertension

3.2. Interstitial lung disease

3.4. Sleep-disordered breathing 3.5. Alveolar hypoventilation disorders 3.6. Chronic exposure to high altitude 3.7. Developmental abnormalities

neurofibromatosis, vasculitis

on dialysis.

54 (1): S43–54

immunodeficiency virus.

**2. Epidemiology**

Adapted with permission from ELSEVIER.(ref 11)

1=. Pulmonary veno-occlusive disease (PVOD) and/or pulmonary capillary hemangiomatosis (PCH)

5.2. Systemic disorders: sarcoidosis, pulmonary Langerhans cell histiocytosis: lymphangioleiomyomatosis,

ALK1 = activin receptor-like kinase type 1; BMPR2 = bone morphogenetic protein receptor type 2; HIV = human

**Adapted from** Simonneau et al. Updated clinical Classification of pulmonary hypertension. J Am Coll Cardiol 2009; Vol.

Pulmonary arterial hypertension (PAH) is a rare disease, with an estimated prevalence of 15-50 cases per million.[4] Idiopathic PAH (IPAH) has an annual incidence of 1-2 cases per million people in the US and Europe and is 2-4 times as common in women as in men.[5], [6] The REVEAL Registry demonstrates a 4.1:1 female-to-male ratio among patients with IPAH, and a 3.8:1 ratio among those with associated pulmonary arterial hypertension (APAH). [4] The mean age at diagnosis is around 45 years.[7] IPAH accounts for at least 40% of cases of PAH,

The REVEAL Registry population tends to be overweight, with a BMI of 29 kg/m[2]; hence, obesity may be a risk factor for the development of PAH. A variety of comorbid conditions

5.3. Metabolic disorders: glycogen storage disease, Gaucher disease, thyroid disorders

**Table 1.** Updated Clinical Classification of Pulmonary Hypertension (Dana Point, 2008)

with APAH accounting for the majority of the remaining cases. [8]

5.4. Others: tumoral obstruction, fibrosing mediastinitis, chronic renal failure

Pulmonary arterial hypertension (PAH) is comprised of idiopathic, heritable and associated forms. IPAH was previously referred to as primary pulmonary hypertension. During the 4th World Symposium on pulmonary hypertension in 2008 at Dana Point, California, USA, the group updated the Evian –Venice classification of 2003 of pulmonary hypertension based upon mechanism. 2 (Table 1)
