Annex A > Chapter 3 - Developments in the UK, in the Diagnosis and Treatment of Congenital Heart Abnormalities in Children, 1984-1995 > Diagnosis and initial assessment > Cardiac catheterisation

Cardiac catheterisation

20 This invasive investigation has always been the `gold standard' for diagnosing congenital heart abnormalities. It involves inserting a long, fine tube (catheter) into either the vein or artery (or both), usually at the top of the leg (femoral vein and artery), usually through a needle puncture, and then guiding the catheter into the heart. Pressures are measured within the different chambers of the heart and the blood vessels leading into and out of the heart. Blood samples are taken to measure their oxygen content. In order to obtain pictures of the structure of the heart and its abnormalities, an imaging technique called `angiocardiography' came into widespread use around the 1950s. X-ray contrast material or dye is injected into specified chambers of the heart through the catheter and its passage through the chambers and the blood vessels is recorded on X-ray film or by video techniques.

21 The overall risk to the patient of cardiac catheterisation has been low throughout the 1980s and onwards, the mortality being around 1%. However, the risk to the small infant is significantly greater for several reasons. Any procedure in an infant who is already sick and in heart failure adds to the risk. A general anaesthetic is usually given. The blood vessels and heart are small structures and there is a risk of damaging them during the procedure. It is preferable to avoid doing a cardiac catheterisation if sufficient information can be obtained by non-invasive methods. However, it must always be remembered that a cardiac surgeon requires as complete a diagnostic picture as is possible before embarking on an operation.

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