Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare and progressive disease characterised by remodelling of the pulmonary arteries and progressive narrowing of the pulmonary vasculature. This leads to a progressive increase in pulmonary vascular resistance and pulmonary arterial pressure and, if left untreated, to right ventricular failure and death. A correct diagnosis requires a complete work-up including right heart catheterisation performed in a specialised centre. Although our knowledge of the epidemiology, pathology and pathophysiology of the disease, as well as the development of innovative therapies, has progressed in recent decades, PAH remains a serious clinical condition. Current treatments for the disease target the three specific pathways of endothelial dysfunction that characterise PAH: the endothelin, nitric oxide and prostacyclin pathways. The current treatment algorithm is based on the assessment of severity using a multiparametric risk stratification approach at the time of diagnosis (baseline) and at regular follow-up visits. It recommends the initiation of combination therapy in PAH patients without cardiopulmonary comorbidities. The choice of therapy (dual or triple) depends on the initial severity of the condition. The main treatment goal is to achieve low-risk status. Further escalation of treatment is required if low-risk status is not achieved at subsequent follow-up assessments. In the most severe patients, who are already on maximal medical therapy, lung transplantation may be indicated. Recent advances in understanding the pathophysiology of the disease have led to the development of promising emerging therapies targeting dysfunctional pathways beyond endothelial dysfunction, including the TGF-β and PDGF pathways.

[Peripheral small airway dysfunction differences between idiopathic pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension]

Objective: To investigate the peripheral small airway dysfunction differences between idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Methods: Impulse oscillmetory system testing (IOS) and pulmonary function testing (PFT) were performed in IPAH and CTEPH patients and 30 healthy control group. We also carried out a subgroup analysis depending on their medical history of airway diseases. Results: We included 42 IPAH and 47 CTEPH patients (with or without airways disease: 8 vs. 34 and 17 vs. 34, respectively). Compared with CTEPH patients, IPAH patients were younger but had more serious pulmonary vessel resistance and mean pulmonary arterial resistance. Compared with IPAH patients, CTEPH patients had significant impaired peripheral small airway dysfunction with decreased of MEF(50) (% pred), MMEF(75/25) evaluated by PFT and R5-R20, Δ R5-R20 and AX measured by IOS [10.6(2.0, 33.0) vs. 2.5(-5.0, 16.5); 22.1(14.0, 32.6) vs. 15.5 (7.0, 23.2); 7.64(4, 18.6) vs. 6(3, 11) respectively, all P<0.05]. Subgroup analysis revealed there were no significant peripheral small dysfunction differences in IPAH patients with or without airway diseases. CTEPH patients had a higher proportion of airway diseases and more serious peripheral dysfunction than IPAH patients with airway diseases. Compared with control healthy group, peripheral airway dysfunction was more obvious even in IPAH and CTEPH patients without airway diseases. Conclusion: Compared with IPAH, CTEPH patients were older, but had better hemodynamics and a higher proportion of airway diseases. The peripheral airway dysfunction were more serious in CTEPH patients without airway diseases than IPAH patients without airway diseases and healthy controls group.

CHANGES IN PULMONARY VASCULATURE IN LUNG DISEASES WHICH LEAD TO PULMONARY HYPERTENSION

The pulmonary vasculature was studied in lung biopsy/autopsy specimens of 20 cases, in conditions likely to lead to pulmonary hypertension. The changes were classified as per Edward and Heath classification and morphometric measurements to gauge medial and intimai hypertrophy were done. Medial hypertrophy was found to be the earliest and commonest change in all cases, irrespective of the pathogenic mechanism of pulmonary hypertension. Variable changes specific to various arteriopathies/vasculopathies were noted.