Pulmonary hypertension: When high blood pressure hits vessels of the lungs

Early signs of pulmonary hypertension are relatively mild and mimic common conditions such as asthma, poor fitness or anxiety. [Courtesy]

Many people are familiar with hypertension, commonly described as high blood pressure, and widely known as a major risk factor for heart attacks, strokes, kidney disease and premature death. Many people live with it for years without symptoms, while others experience headaches, dizziness or fatigue.

According to the World Health Organisation (WHO), hypertension is one of the leading causes of death globally and affects more than one billion people worldwide. In Kenya, national surveys according to WHO’s Eastern Mediterranean Regional Office (EMRO) suggest that nearly one in three adults has raised blood pressure, yet awareness, treatment and control remain low. This shared familiarity with hypertension, however, rarely extends to other forms of dangerous pressure within the body.

Pulmonary hypertension is far less recognised, yet equally serious. Dr Mohamed Hasham Varwani, an Interventional Cardiologist and Assistant Professor of Medicine at the Aga Khan University Hospital Nairobi, defines pulmonary hypertension (PH) as high pressure in the blood vessels of the lungs. This is a different sort of pressure problem. Instead of affecting the body’s main circulation, it affects the blood vessels of the lungs. The result is strain on the right side of the heart and symptoms many mistake for being out of shape.

“Pulmonary hypertension is relatively rare, but it is under-recognized as a cause of persistent lack of breath. Because the early signs are relatively mild and mimic common conditions such as asthma, poor fitness or anxiety,” explains Dr Varwani. “People can go for many years without the right diagnosis yet if left untreated, PH can quietly progress to heart failure and even death. That is why clinicians are calling it a silent epidemic.”

To understand how PH develops, it helps to understand how the heart and lungs work together. “Your heart has two sides. The left side pumps oxygenated blood around the body. The right side pumps blood through the pulmonary arteries into the lungs to pick up oxygen,” Dr Varwani explains.

In pulmonary hypertension, the blood vessels in the lungs become narrowed, stiff or blocked, causing pressure to rise inside them. The right side of the heart must then pump against this resistance every day. Over time, the right ventricle enlarges, weakens and eventually fails, a condition known as right sided heart failure.

As blood flow through the lungs becomes more difficult, less oxygen reaches the body and brain. People are left breathless, exhausted and dizzy, with the heart beating faster in an attempt to compensate.

Pulmonary hypertension is not a single disease but rather the end result of many different processes. Experts classify its causes into several broad groups. One group is pulmonary arterial hypertension, where the disease primarily affects the lung arteries themselves. This form is rare and may be inherited, linked to autoimmune diseases, triggered by certain drugs or occur without a clear cause, which doctors call idiopathic.

Another and far more common cause is pulmonary hypertension due to left heart disease. Long standing high blood pressure, heart failure and valve diseases such as mitral stenosis fall into this category and account for most cases worldwide.

Lung diseases that reduce oxygen levels, including chronic obstructive pulmonary disease, pulmonary fibrosis and sleep apnoea, also lead to PH. Another important cause is chronic thromboembolic pulmonary hypertension, which results from repeated or untreated blood clots in the lungs. This form is significant because it can sometimes be cured with the right surgical or interventional procedure.

HIV associated PH

Other less common causes include conditions such as sarcoidosis, advanced liver disease, blood disorders including sickle cell disease and infections like schistosomiasis.

“Kenya’s reality is that many of these conditions are commonly present here including poorly controlled systemic hypertension, valve disease, chronic lung disease from smoking or biomass exposure, HIV and sickle cell disease,” Dr Varwani notes.

Although HIV associated PH is rare, it is significant at a population level. Sickle cell disease related PH is also an important contributor in Africa. This mix of conditions means PH is not rare in practice once clinicians actively look for it among high risk groups.

Globally, strictly defined pulmonary arterial hypertension is uncommon. When all causes are considered, pulmonary hypertension is estimated to affect about one per cent of the world’s population. According to the National Centre for Biotechnology Information (NCBI), most cases occur in low and middle income countries, where rheumatic heart disease, lung disease, parasitic infections and late diagnosed heart conditions are more prevalent.

Clinic based studies by the National Institutes of Health (NIH) consistently show that PH is common among people with heart failure, advanced valve disease, chronic lung disease and sickle cell disease in Kenya.

Symptoms of pulmonary hypertension usually develop slowly. Early signs include breathlessness during exertion such as climbing stairs or walking uphill, fatigue, reduced stamina, chest tightness during activity, dizziness or fainting and palpitations.

Mistaken for asthma

Because these symptoms are non-specific, many people attribute them to ageing, stress, weight gain or poor fitness. Dr Varwani points out that limited awareness among health care providers means PH is often mistaken for asthma, delaying the correct diagnosis for months or even years.

Without treatment, pulmonary hypertension places strain on the right side of the heart. “Over time, the right ventricle fails,” Dr Varwani explains.

As the condition worsens, patients develop severe breathlessness, leg swelling and abdominal swelling due to fluid accumulation. Complications may include abnormal heart rhythms, coughing up blood, fainting, multi organ congestion affecting the liver and kidneys and in severe cases sudden death.

Diagnosis begins with careful listening to the patient’s story and a thorough examination. An echocardiogram is usually the first test, estimating pulmonary pressures and assessing heart structure and function. Further tests such as blood work, CT scans and sometimes cardiac catheterisation help confirm the diagnosis and identify the underlying cause. Because evaluation is complex, best practice is assessment within a dedicated pulmonary hypertension programme.

While cure is rare except for specific subtypes, modern treatment has dramatically improved outcomes. Management focuses on treating the underlying cause and the pulmonary hypertension itself. Dr Varwani notes that effective medications are now available in Kenya and work by relaxing lung blood vessels and lowering pressure.

Oxygen therapy, supervised exercise, vaccinations, weight management and careful planning around travel and pregnancy are also essential. Untreated PH often progresses to early death, while treated disease can stabilise and sometimes improve, especially when diagnosed early. Awareness, early recognition and timely care are the most powerful tools against the condition.