Pulmonary hypertension is a potentially life-threatening condition caused by high blood pressure in the arteries of the lungs, which leads to damage to the right side of the heart. The condition can lead to death from heart failure within a few years.
In the UK, around 8,000 people are diagnosed with pulmonary hypertension. But because the condition is often difficult to diagnose, the true number of people affected could be much higher.
The BHF has funded research into this condition since the 1960s. This has helped to develop the medicines used today to treat pulmonary hypertension, which give people a better quality of life and can even extend their lifespan.
What mountains have taught us about pulmonary hypertension
Professor Donald Heath at the University of Sheffield in the late 1950s was one of the first people in the world to describe how pulmonary hypertension develops: in particular he described how the structure of the blood vessels in the lungs changes and the heart is damaged by the disease. His remarkable work shed light on a condition that was still almost unknown and paved the way for future work to understand why this happens and develop new medicines to treat it.
To understand pulmonary hypertension, Professor Heath joined forces with Professor Peter Harris, the very first BHF Professor, appointed in 1966 at University College London. They were particularly interested in understanding why humans and animals living at high altitude do not develop pulmonary hypertension. Normally, the low oxygen level at high altitudes would cause the arteries in the lungs to contract and raise the pressure, like what is observed in pulmonary hypertension. Together they studied how animals and humans had adapted to living at high altitude.
Professors Heath and Harris led expeditions to the Andes and Himalayas. In the 1980s they found new insights into how animals adapt to those extreme conditions. Over generations, the lungs of yaks have adapted to high altitude by stopping the normal response of the blood vessels in the lungs, which tend to contract in response to low oxygen. This increases the blood pressure in the lungs, and so is harmful in a permanently low-oxygen environment.
Understanding how the body regulates blood pressure in the lungs was key to understanding how pulmonary hypertension develops, and therefore to developing medicines to treat it.
Developing new treatments
In the 1980s, researchers around the world were trying to identify how your body controls blood pressure – specifically, the way blood vessels expand and contract, as this defines your blood pressure. BHF Professor Andrew Henderson in Cardiff was interested in a molecule produced by cells in the blood vessel wall, which causes blood vessels to dilate. His work was a critical part of the research that led to the identification of the molecule by other researchers as the gas nitric oxide (NO), a discovery that was rewarded with the Nobel Prize for Medicine or Physiology in 1998.
Building on all this research, BHF-funded research by Professor Tim Higenbottam at the University of Cambridge in the late 1980s showed that having low levels of NO in the blood vessels of the lungs is a key factor in pulmonary hypertension. For the first time, they gave NO to people with severe pulmonary arterial hypertension (a specific form of pulmonary hypertension) and showed that it reduced the blood pressure in their lungs.
This pioneering work paved the way for the development of further treatments that target the way blood vessels release NO. As a result, new drugs called phosphodiesterase inhibitors were developed. One of the best known is sildenafil, better known as Viagra (which was accidentally discovered to also dilate blood vessels elsewhere in the body). In 2005, BHF-funded work by Professors Martin Wilkins and Lan Zhao at Imperial College London first demonstrated the benefits of using sildenafil to treat pulmonary hypertension. Today, sildenafil and related drugs are the most prescribed medicines in the UK and worldwide for the treatment of pulmonary hypertension, helping to relieve breathlessness and improving lives.
However, these drugs alone are not sufficient to halt the progress of the disease. The BHF is currently supporting further research across the UK. Professor Allan Lawrie in Sheffield and Professor Mandy MacLean at the University of Strathclyde are among the researchers who have identified promising new ways to tackle pulmonary hypertension. These could lead to the development of new pulmonary hypertension treatments in the future.
BHF support for research into pulmonary hypertension over the last 60 years has been crucial to making the UK one of the world leaders in the field and has contributed significantly to improving survival and quality of life for people with pulmonary hypertension.
First published 1st June 2021