Pulmonary function, CT and echocardiographic abnormalities in sickle cell disease
Alan Lunt, Sujal Desai, Athol Wells, David Hansell, Sitali Mushemi, Narbeh Melikian, Ajay Shah, Swee Lay Thein, Anne Greenough
Published in the journal Thorax, August 2014
Sickle Cell Disease (SCD) is amongst the most prevalent genetic diseases worldwide. Only being inherited if both of one’s parents carry a ‘faulty’ gene in their DNA, SCD affects the Haemoglobin molecules that carry oxygen in the blood, distorting the shape of the red blood cells into so-called crescent shaped ‘sickles’.
It has been shown previously that the majority of adults with SCD have changes in their lungs that can be found on a CT scanner, a high powered X-ray scanner that can create a detailed 3D image of the lungs, including airways and blood vessels.
This study showed that findings like particularly large blood vessels in the lung were linked to reduced lung function. This study aimed to show a link between these changes in the lung and the resulting changes in heart function that one can view on an ‘echocardiogram’ in the same group of patients. An ‘echocardiogram’ is a scanner used to observe the way in which the heart functions, from ultrasound waves ‘bouncing’ off the heart. It can view the structure of the heart and vessels, as well as blood flow. In SCD the heart has to pump more blood through the lungs in order to deliver enough oxygen to the tissues.
Adults with SCD were assessed using CT, echocardiography, and other lung function tests such as lung capacity, between the years 2009-2013. This same group of adults had previously been shown to have lung changes on CT scans between 2003-2005.
Whilst there was a large variety in the lung function of the 28 patients with altered lung features, it was demonstrated that lung structure changes seen on CT scans was related to the patients’ decline in lung function, and changes in the function of the heart displayed on echocardiogram tests. Importantly, the results of the study suggest that some of the changes found in the blood vessels between the heart and lungs may be able to explain the differences in the lungs found on CT scan and the decline in lung function. The results of this study help us to understand the complex relationships between heart, lung and blood vessel function in SCD.
This summary was produced by David Launer, Year 12 student from JFS School, Harrow, as part of our departmental educational outreach programme.