A physiological left-to-right shunt through a patent foramen ovale (PFO) can be demonstrated in 32-55% of young adults with unexplained stroke compared with 10-35% of the general population.1 Transoesophageal or transthoracic echocardiographic evidence of a PFO consists of demonstration of a defect in the wall between the atria and ideally the passage of bubble contrast from right to left.at this level. Provocative measures may be used to raise right atrial pressure, such as coughing, Valsalva jnanoeuvre or pressure on the liver, and increase the detection rate of PFO by at least 25%, but are not always performed rigorously or even routinely in children.
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