Aktueller stand der diagnostik des offenen foramen ovale

The prevalence of patent foramen ovale (PFO) in healthy individuals is estimated to be about 25% and is elevated to 60% in young patients with kryptogenetic stroke. Pathophysiologically during unvoluntary Valsalva manoeuvres a paradoxical embolism from the venous to the arterial system often occurs. To date, transesophageal echocardiography (TEE) was considered to be the most sensitive way to detect PFO. TEE, however, is semiinvasive, and there are a number of serious complications such as bleeding, hypoxia, bronchospasm, cardiac arrhythmias, bacteremia and sudden cardiac arrest. Transcranial Doppler sonography of the middle cerebral artery during contrast injection [Echovist (c-TCD)] has recently been proposed as an alternative method for the detection of PFO. In a PFO-positive case the typical Doppler wave spectrum is overlapped by high intensity transient signals (HITS) which are caused by the contrast bubbles in the blood stream. However, in the literature and in our own experience there are single cases with false negative results in TEE or in c-TCD. Both methods have a sensitivity of approximately 90% and a specifity of 100%. TEE and TCD-Echovist, used separately, have the small risk of false negative result. Combined use of both methods, however, increases the PFO detection rate.