Transcranial Doppler Detection of Venous-to-Arterial Circulation Shunts: Criteria for Patent Foramen Ovale

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Abstract

Purpose.

As paradoxical embolism is associated with stroke in young adults, migraine, and decompression sickness, the detection of venous-toarterial circulation shunt (v-aCS), such as patent foramen ovale (PFO), is increasingly important. We compared a rigorous transcranial Doppler (TCD) protocol with transesophageal echocardiography (TEE) to develop criteria for PFO.

Methods.

Standardized TCD was performed 2 weeks before simultaneous TEE and TCD in 39 patients aged 15-39 following ischemic stroke (n = 33) or myocardial infarction (n = 6). V-aCS was investigated by contrast sonography. During standardized TCD, contrast injections were performed twice, at rest and with cough and Valsalva maneuvers. TCD and TEE were recorded and analyzed independently by ‘blinded’ observers.

Results.

All 16 of the 39 patients with PFO on TEE had more than 15 micro-emboli on standardized TCD; in 14 of these 16, paradoxical embolization required no provocation. Three of 9 patients with ‘major’ v-aCS (>50 microbubble emboli at rest or >10 at rest with >80 on provocation) on standardized TCD were not identified by TEE as having large shunts.

Conclusion.

The standardized TCD protocol is sensitive in the diagnosis of PFO and with the use of provocation maneuvers measures the functional importance of v-aCS more accurately than TEE.

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