TRANSESOPHAGEAL ECHOCARDIOGRAPHY AND CONTRAST-TCD IN THE DETECTION OFA PATENT FORAMEN OVALE - EXPERIENCES WITH 111 PATIENTS

Patent foramen ovale (PFO) is increasingly recognized in association w ith cryptogenic stroke. Using transesophageal echocardiography (TEE) a nd transcranial Doppler sonography with ultrasonic contrast medium (co ntrast-TCD), we evaluated the frequency of a PFO as the fundamental co ndition of paradoxical embolism in 111 patients after cerebral ischemi a. There was a right-left shunt in 50 patients (45%) with TEE. In 31 o f 40 patients with stroke of unknown etiology, a PFO was the only dete ctable finding associated with cerebral ischemia. Using TEE as the ''g old standard,'' the sensitivity of contrast-TCD was 91.3%, specificity 93.8%, and the overall accuracy 92.8%. Contrast-TCD failed to detect a right-left, shunt in four patients, but there were four other patien ts with negative TEE and positive contrast-TCD. We conclude that contr ast-TCD is a highly sensitive method for detecting a right-left shunt. Its advantages are low cost, its ability to detect single contrast-me dium embolism, and control of the Valsalva maneuver by observing the d ecrease of cerebral blood flow. Evidence of PFO in cryptogenic stroke should prompt a search for a subclinical venous thrombosis as the embo lic source.