Echocardiographic detection and transcranial doppler quantification of right-to-left shunting

Eustaquio Maria Onorato, Francesco Casilli, Gian Paolo Anzola

Research output: Chapter in Book/Report/Conference proceedingChapter


Ultrasound technology have made available many non-invasive techniques for diagnosing a right-to-left shunting (RLS), such as transthoracic echocardiography, transesophageal echocardiography and transcranial Doppler ultrasound. Echocardiographic examination defines patent foramen ovale(PFO) as flap-like opening in the atrial septum secundum, with the septum primum serving as a one-way valve allowing for permanent or transient right-to-left shunt. Transthoracic (TTE) and transesophageal (TEE) echocardiography with saline contrast injection in basal conditions and after Valsalva maneuver have been considered sensitive methods to detect PFO. Although TTE may identify patients with RLS, TEE with saline contrast injection is more sensitive by allowing visualization and microbubbles count in the left atrium that would otherwise be filtered by the lung capillary. Echocardiographic assessment particularly by TEE is of paramount importance for the morphological evaluation of PFO. Different anatomic characteristics such as long-tunnel PFO, large atrial septum aneurysm, prominent Eustachian valve, multiperforated fossa ovalis or lipomatous rims, often combined with each other, may have an impact on immediate procedural results and outcomes. On the other hand, transcranial Doppler (TCD) is unable to locate the source of RLS but is likely to represent the most valid alternative to the so called gold standard Doppler TEE for its high sensitivity and specificity, relative ease of execution and little discomfort to the patients; it may even be superior to assess the functional consequences of RLS, especially so in those cases in whom postural variations in the amount of shunted blood may be present and can be easily detected, a task almost impossible with echocardiography. It has been suggested that it is precisely the amount of shunt as assessed in the cerebral vessels by contrast TCD that may constitute the principal determinant of stroke occurrence and relapse. Therefore, the assessment of RLS by TCD represents a precioustool to help stratify patients according to their risk profile. Furthermore, contrast TCD isideal for follow-up studies, because it is easily repeatable and sensitive enough to detect also minor residual shunts.

Original languageEnglish
Title of host publicationPatent Foramen Ovale
PublisherSpringer-Verlag London Ltd
Number of pages15
ISBN (Print)9781447149873, 9781447149866
Publication statusPublished - Jan 1 2015


  • Contrast echocardiography
  • Contrast transcranial doppler
  • Patent foramen ovale
  • Right-to-left shunting
  • Transesophageal echocardiography
  • Transthoracic echocardiography

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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