Systemic Sclerosis-Associated Pulmonary Arterial Hypertension (SSc-PAH)

Pulmonary hypertension (PH) means high blood pressure within the pulmonary arteries, that may lead to additional strain being placed upon the heart. Early signs include persistent breathlessness that may be so mild at first that you barely notice it. If this sounds familiar, it is important to talk to your doctor.

What is systemic sclerosis-associated pulmonary arterial hypertension (SSC-PAH)?

Pulmonary arterial hypertension (PAH) can occur in systemic sclerosis when fibrosis causes the pulmonary arteries to narrow, raising blood pressure within these vessels and placing additional strain upon the heart. This may lead to damage to the right side of the heart, so that it has to work harder. When the cause is narrowing of the small blood vessels this is pulmonary arterial hypertension (PAH), which is a possible complication of systemic sclerosis (SSc-PAH).

About SSc-PAH

The pulmonary arteries are the main blood vessels carrying blood to the lungs from the heart. In SSC-PAH, inflammation and scarring within the blood vessels of the lungs lead to the thickening of the walls of the pulmonary artery. This prevents it from being able to open up easily to relieve the pressure of the blood inside, leading to a build-up of pressure in the vessels feeding into the lungs from the heart, so that blood pressure in the pulmonary artery is higher than normal. This affects the small blood vessels of the lungs, with less blood reaching the lungs and less oxygen carried within the bloodstream. The high pressure then leads to a stretching of the right side of the heart, meaning that it has to work harder. 

Around one-in-ten people with scleroderma may develop PAH, which can be associated with a number of other conditions as well.  In many cases, SSc-PAH will not develop until many years after the onset of systemic sclerosis. What causes someone to develop this condition is unclear. Research is ongoing, and it is thought that there may be a link to certain other complications of SSc, including lung scarring (pulmonary fibrosis) and stiffening of the heart.


In many cases, the onset of SSc-PAH can be very slow, with early symptoms so mild that you barely notice them. It is therefore vital to be aware of the signs to look out for, and to tell your doctor if you notice any changes. Symptoms are caused by either reduced oxygen levels in the bloodstream or by additional strain being placed upon the heart:

  •  Shortness of breath with minimal exertion
  • Tiredness
  • Fatigue
  • Dizzyness or lightheadedness
  • Chest pain, especially on exertion
  • Swelling in the feet or ankles.


    Because there are effective treatments available for SSc-PAH, early detection is vital. Annual testing that is designed to monitor disease progression is an essential part of managing your condition and will detect any changes early on.

    If you have systemic sclerosis, you should be offered these tests routinely, so it is important to ask your doctor if they are not being carried out.

    If PAH is suspected, initial investigations will often be performed by your rheumatologist. If necessary, you can be referred to one of the specialist PH centres in the UK. These investigations may include all of the following:

    • Ultrasound of the heart (echocardiogram)
    • Breathing tests (pulmonary function tests)
    • Exercise tests
    • X-rays (including CT and MRI)


    There are a number of effective treatments for SSc-PAH, and the best option will depend on several factors, including the severity of symptoms. 

    Conventional therapies

    These are treatments designed to help maintain your wellbeing and help you to live as actively as possible.

    • Oxygen therapy: living with PAH means that the heart and lungs are working harder to supply the body with the oxygen it needs. This can lead to fatigue and shortness of breath. Oxygen therapy helps to relieve these symptoms, by increasing the level of oxygen in the bloodstream. It can also help to reduce the pressure on the pulmonary artery, by relaxing the blood vessels of the lungs.
    • Anticoagulants: some forms of PAH carry an increased risk of developing blood clots. Anticoagulant medicines including warfarin can help to prevent this and enable blood to flow more freely.
    • Diuretics or water tablets: these work by increasing urine output and are used to remove excess fluid from the body to reduce the strain upon the heart. Removing water from the blood dcreases the amount of fluid within the blood vessels, which also reduces pressure. Diuretics also treat symptoms like swollen ankles.

    Targeted therapies

    This group of treatments have the aim of slowing down the progression of your condition.

    • Calcium channel blockers: these are vasodilators that are used to help open up the blood vessels. This group of medications includes nifedipine, diltiazem, nicardipine and amlodipine.
    • Endothelin receptor antagonists (ERAs): these are a form of targeted therapy that is used to slow the progression of PAH and even reverse some of the damage to the heart and lungs. They work by reducing the level of endothelin within the blood. Endothelin is a factor in the narrowing of blood vessels that can affect the vessels of the lungs by causing them to narrow, increasing blood pressure within the pulmonary arteries. Reducing the level of endothelin in the blood can limit the damage that it can cause. These medications include bosentan, ambrisentan and macitetan.
    • Phosphodiesterase 5 (PDE 5) inhibitors: this is another targeted therapy that aims to slow progression and limit some of the damage to the heart and lungs.  PDE 5 inhibitors are widely used as a treatment for erectile dysfunction, because the blood vessels are so similar. They work by inhibiting an enzyme called phosphodiesterase type 5 [PDE5] from working, which helps blood vessels to relax, increasing blood flow and lowering blood pressure. Phosphodiesterase 5 inhibitors include sildenafil and tadalafil.
    • Prostanoids: these are powerful vasodilators that are used to enable blood to flow more freely through the vessels of the lungs, ultimately reducing the strain upon the heart. This group of medications work in a similar way to prostaglandins, that occur naturally within the body. In the longer term, the beneficial effect upon the heart may mean that it is able to work more efficiently. Examples of prostanoids include epoprostenol, iloprost and treprostinil.
    • Soluble guanylate cyclase stimulators: these are a form of targeted therapy used to slow down disease progression. It is prescribed in the form of Riociguat tablets, that work by causing the blood vessels in the lungs to dilate.
    • Inhaled treatments: these include nebulised iloprost. This is a vasodilator used to open up the blood vessels of the lungs, allowing blood to flow more freely.

    Pulmonary rehabilitation

    Pulmonary rehabilitation (PR) is a programme of exercise and education that is designed to help people living with lung disease who are affected by breathlessness.

    It combines tailored exercise with the provision of information, with the aim of enabling people to better understand their conditions, the associated breathlessness, and other symptoms.

    A PR course will usually last for up to eight weeks, typically involving two weekly sessions, that would usually be held as group sessions in the absence of coronavirus restrictions, usually with the hospital or other community setting. Sessions will include a program of information together with a tailored programme of exercise, including aerobic exercise and resistance support. The course will be delivered by a team of health professionals who have undergone training in PR including physiotherapists, occupational therapists and nurses.

    PR has been found to enable people to walk further and carry out day-to-day tasks more easily. For more information or to ask for a referral, talk to your doctor.

    Managing Your Wellbeing

    Living with this condition is likely to mean that you become tired more easily, or you may become breathless when walking short distances or climbing the stairs. Pacing yourself and recognising when you need to slow down will help you to manage your symptoms and keep on living life to the fullest.

    Whenever you can, try to save vital energy for the things that are important to you. If you enjoy meeting friends or a doing a particular activity, accepting help when available and planning ahead to conserve energy will help you to continue doing the things you enjoy.

    It is important to take steps to stay as healthy as possible, and optimising your lifestyle may even help slow down the progression of your condition. Taking regular exercise within your comfort zone will not make your condition worse, and it is important to remain as active as you can; for your emotional wellbeing as well as for your physical health. Even a very short walk can make a real difference. Try not to overdo it, as it is important not to become tired from over-exertion and sometimes a small amount every day is enough.

    More information and finding support

    SRUK are here to support you and we offer a number of ways to access information and resources, find support and connect with others who may be in a similar situation. Please give us a call on 020 3893 5998 and we will be very happy to help you. 

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