Doctors involved in the prediction, treatment and prevention of heart problems could soon have a new arrow in their quiver: a thermometer. Hot spots in the blood vessels supplying the heart, as Christodoulos Stefandis of Paleo Psychio, Athens, Greece, and colleagues reveal in
Stefandis' group used a tiny temperature probe on the end of a long, fine tube to take suites of highly accurate and localised measurements inside normal and diseased coronary arteries. They studied 45 people with healthy hearts and a further 45 with various degrees of atherosclerosis – the kind of thickened and weakened artery walls that reduce blood flow to the heart, causing heart failure.
What emerged is that the temperature at different points in healthy arteries is uniform. In the occluded, at-risk arteries of angina and heart-attack patients, however, temperature is far more heterogeneous because the fatty deposits – so-called 'plaques' – responsible for narrowing the vessels are actually hotter than the surrounding walls.
Moreover the magnitude of this temperature variation within an artery seemed to be directly related to the severity of a subject's heart condition. In other words, heart-attack patients showed the greatest difference in site-to-site plaque temperatures, whereas patients with mild angina showed the least. An intriguing finding given that all these syndromes are, in terms of plaque thickness and number, very similar.
It is not yet clear how this extra heat is being generated and what exactly it means. But it adds to a growing body of evidence that infection and inflammation – both of which raise temperature – play a key part in the progression of heart disease. A theory further supported by the researchers' discovery of high levels of 'C-reactive protein' in the plaques, which is known to indicate inflammation and infection.
The rupture of atherosclerotic plaques and the clots that can form as a result are the main cause of heart attacks, but as yet these events cannot be reliably predicted. Stefandis and colleagues findings hint that this could soon change. Indeed, if confirmed by larger studies, "the concept of thermal heterogeneity may be applied by other specialities," they suggest, "[for] the detection of inflamed or malignant cells in other organs."