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the doctor can give appropriate treatment. While you lie flat on a table, your blood pressure, pulse and ECG are monitored. The table is then tilted to an angle of 60 to 75 degrees and monitoring is continued. If nothing happens, a spray of a substance called GTN is given under your tongue as a stimulus and you will be monitored for another 10-15 minutes. The table will then be returned to the flat position and the leads disconnected. The whole test takes around 45 minutes. If your blood pressure falls at the same time as you suffer your usual symptoms, this means that you have vasovagal syndrome or a related condition.


Figure 8: The tilt table test The tilt table test involves monitoring the ECG, pulse and blood pressure while you are lying flat on a table, then when the table is tilted to 60-75 degrees, and then lying flat again.


Genetic testing In most of the channelopathies, cardiomyopathies, Marfan syndrome and familial hypercholesterolaemia, mutations of specific genes have been detected that are thought to cause a specific disease. So, in principle, if we could identify these mutations, we would be able to make a diagnosis in any DNA sample, including any obtained from SADS or sudden death victims at their autopsy or from relatives who have given blood. Unfortunately, this cannot be done at the moment because we don’t have complete knowledge of all the genes involved in every condition. For example, 7 in every 10 people known to have LQTS have mutations of known identified genes. Also, many variations in the DNA code are found in a large number of people and do not necessarily cause any disease. Many families with LQTS have


Cardiac Risk in the Young 32


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