Pulmonary Hypertension - DRAFT

Overview

Pulmonary hypertension (PH) is an increase in mean pulmonary arterial pressure (PAP), which can be caused by or associated with a wide variety of conditions.

Idiopathic pulmonary arterial hypertension is a rare disorder that can be defined as a sustained elevation in PAP and pulmonary vascular resistance, with normal pulmonary artery wedge pressure, in the absence of a known cause. It is a diagnosis of exclusion after other possible causes of PH have been excluded. It is a severe and often rapidly progressive illness in many cases. (1)

Secondary pulmonary hypertension is more common in severe respiratory and cardiac disease, occurring in 18-50% of patients assessed for transplantation or lung volume reduction surgery, and in 7-83% of those with diastolic heart failure.

Between 0.5% and 4% of patients develop chronic thromboembolic PH after acute pulmonary embolism. There is an increased risk for patients presenting with large, recurrent or unprovoked clots.

Classification

The World Health Organization (WHO) has devised a classification system (2).

• Group 1 - idiopathic.
• Group 2 - secondary to left heart disease, valvular heart disease, restrictive cardiomyopathy.
• Group 3 - secondary to chronic lung disease and environmental hypoxaemia.
• Group 4 - due to chronic thrombotic disease, embolic disease, or both.
• Group 5 - metabolic disorders, systemic disorders, haematological diseases, and other miscellaneous causes.

Who to Refer

Patients are usually diagnosed in secondary care following referral or investigation of symptoms.

Most commonly, patients present with progressive breathlessness, weakness and tiredness. Exertional dizziness and syncope may also develop. Oedema and ascites tend to occur late in the disease. Angina and tachyarrythmias, particularly atrial flutter, may also occur. Haemoptysis is uncommon but may occur in Eisenmenger's syndrome and chronic thromboembolic PH.

Clinical signs may be subtle or absent in early disease but can include right ventricular (parasternal) heave, a loud pulmonary second heart sound, murmur of pulmonary regurgitation, systolic murmur of tricuspid regurgitation, raised jugular venous pressure, peripheral oedema and ascites. 

There may also be signs of associated conditions, such as connective tissue disease or liver disease.

Red Flags

Patients who are severely unwell or have acute symptoms may need to be admitted or referred to Rapid Access clinics such as:

Respiratory HOT Clinic - if breathless and threatening admission.

Rapid Access Chest Pain Clinic - if chest pain/ suspected angina

What to do before referral

If PH is suspected then consider the following investigations in primary care:

• Bloods - UE, LFTs (portal hypertension), TFTs, and autoimmune screening (particularly antinuclear antibody to detect possible SLE/scleroderma-like syndrome).
• CXR to exclude other lung diseases although CXR is not useful for diagnosing PH.
• ECG - can show right ventricular hypertrophy and strain patterns but may be normal.
• Pulmonary function tests.
• Polysomnography may be used to exclude obstructive sleep apnoea.
• Echocardiography to assess right ventricular function and estimate pulmonary arterial pressures.

Investigations in secondary care may include:

• Lung biopsy may be needed to exclude interstitial lung disease.
• High-resolution CT of the thorax to investigate other possible causes of PH.
• Isotope perfusion lung scanning has high sensitivity for chronic thromboembolic PH.
• MRI - cardiac MRI or pulmonary angiography.
• Right heart catheterisation is needed to confirm the diagnosis by directly measuring pulmonary pressure. 

Referral

From primary care there is no specific directly accessible Pulmonary Hypertension Clinic available via eRS in BNSSG.

Patients should be referred to the appropriate specialty (usually respiratory or cardiology or haematology) depending on symptoms and/or suspected cause.

Advice and guidance services may also be helpful if there is uncertainty about the most appropriate referral route.

Prognosis

The mean survival of people with evidence of right heart failure or severe PH (greater than 55 mm Hg mean pulmonary artery pressure) is approximately 12 months.

For people with preserved right heart function and a mean pulmonary artery pressure less than 55 mm Hg, survival is approximately three years.

Idiopathic PAH patients who are untreated are known to have a median survival of 2-3 years.(1).

Resources

(1) Pulmonary Hypertension. About Pulmonary Hypertension | Patient

(2) Secondary Pulmonary Hypertension - StatPearls - NCBI Bookshelf (nih.gov)

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