Introduction: Ultrasound has been a part of the arsenal of medical specialists for more than 50 years but its uses keep growing with the invention of newer methods in diagnostics of different pathologies. One of them are the atrial septal defects (ASD) and even though the standard transthoracic echocardiography (TTE) has proven its efficacy, there is nowadays, available to professionals, a new and equally reliable diagnostic method - transcranial Doppler ultrasonog-raphy (cTCD).
Materials and Methods: This report reviews the growing capabilities of ultrasound in ASD diagnostics. It is estimated that approximately 25% of the world`s population have patent foramen ovale (PFO). The majority of these people have no symptoms associated with this condition. However, in recent years, it has been suggested that patients with cryptogenic strokes or transient ischaemic attacks (TIA) have higher prevalence of PFO. cTCD is a very sensitive technique which can be used for evaluation of right-to-left shunts (RLS) via PFO. In the diagnostics of ASD transtemporal view is used and the middle cerebral artery (MCA) is visualized. The method is performed by intravenous application of saline and the appearance of microbubbles in the MCA determines with high certainty the diagnosis of ASD.
Results and Discussion: Numerous studies have shown that in large percentage of the patients with strokes or TIA such defect is present and the specificity and accuracy of the method are comparable to those of TTE and transesophageal echocardiography (TEE), which is considered a standard method for detecting RLS.
Conclusion: cTCD has similar sensitivity and specificity to cTEE in detecting ASD but has the advantage of being noninvasive and reportedly safe in patients with embolic stroke of undetermined source. In summary, the availability of high sensitive diagnostic techniques such as TCD provides the opportunity of effective and reliable screening of patients with appropriate indications.
Baumgartner et al, Transcranial Color- Coded Duplex Sonography in the Evaluation of Collateral Flow through the Circle of Willis, AJNR Am J Neuroradiol 18:127–133, January 1997
Kirsch et al , Advances in Transcranial Doppler US: Imaging Ahead, RadioGraphics 2013; 33:E1–E14
AIUM Practice Guideline for the Performance of a Transcranial Doppler Ultrasound Examination for Adults and Children, © 2012 by the American Institute of Ultrasound in Medicine
Lechat P, Mas JL, Lascault G, et al. Prevalence of patent foramen ovale in patients with stroke. N Engl J Med 1988;318:1148–52
Blersch W et al, Transcranial Duplex sonography in the Detection of Patent Foramen Ovale, Radiology 2002; 225:693-699
M. Jauss, E.M. Zanette, for the Consensus Conference, Detection of right-to-left shunt with ultrasound contrast agent and transcranial Doppler sonography, Cerebrovascular Diseases, 10 (2000), pp. 490–496
Geraud Souteyrand et al, Comparison of transthoracic echocardiography using second harmonic imaging, transcranial Doppler and transesophageal echocardiography for the detection of patent foramen ovale in stroke patients, Eur J Echocardiography (2006) 7, 147-154
