Pulmonary Arterial Hypertension (PAH) is a rare, progressive disorder that thickens and narrows the lung arteries, causing an increase in blood pressure. This makes the heart work harder, potentially leading to heart failure with time.
PAH is serious and can be life-threatening, but early diagnosis and treatment can improve life expectancy and quality of life.
In the advanced stage of the disease, the blood vessels in the lungs are narrowed, thickened and stiff, causing difficulty for the heart to pump blood through, causing the heart muscle to weaken over time. Clots can form and block part of the vessel's lumen as well.
When pulmonary hypertension occurs in the absence of a known cause, it is referred to as idiopathic pulmonary arterial hypertension (IPAH). IPAH is extremely rare, occurring in about 2 to 10 persons per a million population per year. Causes of pulmonary arterial hypertension include collagen vascular diseases (e.g. scleroderma, CREST syndrome or systemic lupus erythematosus), congenital heart diseases (shunts like ventricular and atrial septal defects), HIV infection, liver disease and diet drugs like fenfluramine and dexfenfluramine.
Common causes of secondary pulmonary hypertension include lung disorders (emphysema, lung fibrosis, sleep apnea), chronic pulmonary thromboembolism (chronic formation of blood clots in the pulmonary artery), and left heart disease (e.g. mitral stenosis).
Diagnosis of PAH is based on a combination of clinical evaluation and targeted investigations.
A specialist will assess the symptoms through a physical examination which includes:
- Blood tests
- Electrocardiogram (ECG)
- Chest X-ray and/or CT scan
- Echocardiogram
- Lung Function Evaluation
- Cardiac Catheterisation
A comprehensive evaluation with the above investigations is crucial, with cardiac catheterisation being required for a definite diagnosis.
Symptoms of PAH develop gradually over months or years, worsening as the disease progresses. Patients may experience:
- Shortness of breath on exertion
- Feel fatigue easily
- Fainting spells
- Swelling in the lower limbs
Pulmonary hypertension has a poor prognosis and must be investigated. Patients who have symptoms need to be treated early. Outcomes of the treatment is largely dependent on the cause of the disease. Treatment with PAH specific therapy has been shown to improve symptoms, exercise capacity and overall prognosis of the disease.
Drugs that are used specifically for treatment of pulmonary hypertension in Singapore include:
- Phosphodiesterase V inhibitors such as Sildenafil (Viagra), Tadalafil (Cialis)
- Endothelin Receptor Antagonists such as Bosentan (Tracleer)
- Prostaclyclin analogues such as Inhaled Iloprost (Ventavis), Intravenous Epoprostenol (Flolan), thermostable epoprostenol, Veletri
- Guanylyl Cyclase stimulators such as Riociguat
A patient can sometimes require treatment using two or three types of these drugs in combination as their disease progresses.
Drugs that are commonly used to complement the treatment of pulmonary hypertension include:
- Warfarin -This is an anticoagulant that thins the blood.
- Diuretics - Spironolactone, Frusemide (with Potassium Chloride) - these medications helps to remove water logged in the body
- Long term Oxygen therapy - This is offered to patients with low oxygen saturation (< 90%), as oxygen is a good dilator of the pulmonary blood vessels.
Patients with thromboembolic pulmonary hypertension can be assessed with modalities like dual energy CT angiography or rotational angiography. Patients will be assessed for suitability for pulmonary endarterectomy.
Patients with distal embolic disease can be treated with balloon pulmonary angioplasty(BPA).
Patients receive care from a multidisciplinary team, including PAH specialists, nurses, physiotherapist, and pharmacist, ensuring comprehensive support to achieve the best outcomes.
Treatment involves:
- Pulmonary Vasodilators – Medications that relax the lung arteries to allow for smoother passage of blood and hence, reduces heart strain
- Diuretics – Medications that help with fluid retention to eliminate excess water, available in oral or injectable forms
- Oxygen Therapy – May be necessary if oxygen levels are low
- Cardiac Rehabilitation – Exercise training under close supervision of physiotherapist to enhance patient function
