Doppler Detects Heart Defect

Previous studies indicate that 25% of the population, and a higher percentage of patients who have had unexplained strokes, have a patent foramen ovale (PFO), which occurs when an opening between two heart chambers fails to close at birth. Many people never experience symptoms; but a PVO can allow a blood clot that forms in a vein to escape from the right to the left side of the heart, enter the arteries to the brain and cause a stroke (paradoxical embolism). Thus, accurately detecting PFOs, and knowing its grade, can help doctors decide whether a stroke was due to a paradoxical embolism.  J. David Spence from Western University (Canada), and colleagues assessed the reliability of echocardiography—the standard diagnostic for measuring blood flow to the brain, versus transcranial Doppler, finding that echocardiography failed to find the PFO in more than 15% of the 340 patients in the study with the defect.  Importantly, the team reports that some of the shunts were quite large, with about one-quarter of the missed defects rated in the three highest grades of severity.