|Year : 2023 | Volume
| Issue : 2 | Page : 41-42
Pulmonary hypertension in chronic lung diseases
Senior Consultant and HOD, Department of Pulmonary Medicine, Rajagiri Hospital, Kochi, Kerala, India
|Date of Submission||18-Feb-2023|
|Date of Acceptance||25-Feb-2023|
|Date of Web Publication||02-May-2023|
Dr. Rajesh Venkitakrishnan
Rajagiri Hospital, Kochi, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Venkitakrishnan R. Pulmonary hypertension in chronic lung diseases. J Adv Lung Health 2023;3:41-2
Pulmonary hypertension (PH) is a pathophysiological disorder that may involve multiple clinical conditions and may be associated with a variety of cardiovascular and respiratory diseases. The definitions for PH are based on hemodynamic assessment by right heart catheterization (RHC). Although hemodynamics represent the central element of characterizing PH, the final diagnosis and classification should reflect the whole clinical context and consider the results of all investigations. PH is defined by a mean pulmonary arterial pressure (mPAP) of >20 mmHg at rest. The general purpose of the clinical classification of PH remains to categorize clinical conditions associated with PH, based on similar pathophysiological mechanisms, clinical presentation, hemodynamic characteristics, and therapeutic management. Group 3 PH is associated with obstructive or restrictive lung diseases and/or hypoxic states.
PH associated with lung diseases largely outweighs PH due to other causes, just due to the sheer number of patients with chronic lung diseases. The common lung diseases associated with PH include chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD), obesity hypoventilation syndrome, sarcoidosis, chest wall and neuromuscular abnormalities, etc. Of these, COPD and ILD are diseases with high prevalence in the community, and hence, the focus of discussion in the postliterature of group 3 PH. The prevalence of PH in COPD (COPD-PH) is, in general, dependent on the severity of the disease but also on the definition of PH and the method of diagnostic assessment. Specific genetic signatures are also linked with the development of PH in COPD. Several studies in patients with spirometric GOLD Stage IV, showed that up to 90% have mPAP >20 mmHg, with most ranging between 20 and 35 mmHg. Approximately 1%–5% of COPD patients have mPAP >35–40 mmHg at rest. Most of the data on the prevalence and impact of PH-complicating fibrotic lung disorders emanate from the idiopathic pulmonary fibrosis (IPF) literature. In IPF, mPAP ≥25 mmHg has been reported in 8%–15% of patients on initial workup, with a greater prevalence in advanced (30%–50%) and end-stage (>60%) disease.,, In addition, echocardiography studies have suggested a high prevalence of PH.
The diagnostic approach to PH is mainly focused on two tasks. The primary goal is to raise early suspicion of PH and ensure fast-track referral to PH centers in patients with a high likelihood of pulmonary artery hypertension (PAH), chronic thromboembolic PH, or other forms of severe PH. The second objective is to identify underlying diseases, especially LHD (group 2 PH) and lung disease (group 3 PH), as well as comorbidities, to ensure proper classification, risk assessment, and treatment. The investigations to be performed in suspected PH include a chest radiograph, a 12-lead electrocardiogram, echocardiography, etc. Echocardiography (ECHO) is an invaluable tool in the evaluation of PH and has the advantage of being noninvasive. However, echocardiography alone is insufficient to confirm a diagnosis of PH, which requires RHC. Given the heterogeneous nature of PH and the peculiar geometry of the right ventricle (RV), there is no single echocardiographic parameter that reliably informs about PH status and underlying etiology. Therefore, a comprehensive echocardiographic evaluation for suspected PH includes estimating the systolic pulmonary arterial pressure and detecting additional signs suggestive of PH, aiming at assigning an echocardiographic level of probability of PH.,, Echocardiographic findings of PH, including estimating pressure and signs of RV overload and/or dysfunction, are beyond the scope of this editorial. It may be remembered that echocardiography and other noninvasive measures, including an enlarged main pulmonary artery on computed tomography scan, are limited in their accuracy to detect PH in lung diseases, thus serving as screening tools only.
RHC should be performed in patients with chronic lung diseases when significant PH is suspected, and the patient's management will likely be influenced by RHC results, including referral for transplantation, inclusion in clinical trials or registries, treatment of unmasked left heart dysfunction, or compassionate use of therapy. RHC may be considered when:
- Clinical worsening, progressive exercise limitation, and/or gas exchange abnormalities are not deemed attributable to ventilatory impairment
- An accurate prognostic assessment is deemed sufficiently important.
Therapy directed at alleviating pulmonary artery pressure is recommended in idiopathic PAH, drug-induced PH, heritable forms of PH, and connective tissue-related PH. The drug classes include endothelin receptor antagonists, phosphodiesterase 5 inhibitors, prostacyclin analogs, etc., Special mention needs to be made with regard to connective tissue disease-related PH (CTD-PH) because they can primarily involve pulmonary vasculature as well as cause an ILD. Some aspects of PAH-CTD treatment differ according to the associated CTD. Immunosuppressive therapy combining glucocorticosteroids and cyclophosphamide may result in clinical improvement in patients with systemic lupus erythematosis (SLE)- or mixed CTD-associated PAH, while it is not recommended in PAH-SSc. Patients with SSc and other CTDs may have ILD and/or HFpEF, which needs to be considered when initiating PAH therapy. In SSc, the long-term risk/benefit ratio of oral anticoagulation is unfavorable due to an increased risk of bleeding, while Vitamin K antagonists are recommended in PAH-CTD with a thrombophilic predisposition like antiphospholipid syndrome.
The role of specialized centers with expertise in the comprehensive diagnosis and treatment of PH cannot be overemphasized. PH is considered an orphan disease and has gained research focus only in the past 1–2 decades. Registries for PH, especially group 3 PH, are also conspicuous by their absence in our country. The present edition of JALH has published an original study sharing the clinical profile of patients with PH and has revealed a large number of patients (31%) presenting with PH to a tertiary care respiratory unit to be suffering from obliterative bronchiolitis. This may be in sharp contrast to the established literature, which narrates COPD and ILD as common causes of group 3 PH. More research on group 3 PH need to evolve from India, which may serve as an eye-opener to our own patient characteristics.
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