An international Consensus Meeting to determine a standard in the examination technique for the detection of right-to-left shunt (RLS) using contrast transcranial Doppler sonography (TCD) led to the following recommendations to standardize the examination procedure: The patient should be prepared with an 18-gauge needle inserted into the cubital vein and should be in the supine position. Insonation of at least one middle cerebral artery (MCA) using TCD is performed. The contrast agent is prepared using 9 ml isotonic saline solution and 1 ml air mixed with a three-way stopcock by exchange of saline/air mixture between the syringes and injected as a bolus. In case of little or no detection of microbubbles (MB) in the MCA under basal conditions, the examination will be repeated using the Valsalva maneuver (VM). Contrast agent will be injected 5 s before the start of the VM; the overall VM duration should be 10 s. The patient should start the VM on examiner’s command. The strength of the VM can be controlled by peak flow velocity of the Doppler curve. The time when the first MB appears at the MCA level will be noted. A four-level categorization according to the MB count should be applied: (1) 0 MB (negative result); (2) 1–10 MB; (3) >10 MB and no curtain, and (4) curtain. (‘Curtain’ refers to a shower of MB, where a single bubble cannot be identified.) The results should be documented for basal condition and VM testing separately. The clinical significance of the diagnosis of a RLS in a particular patient is not fully evaluated and requires further studies. A minimum amount of MB suggestive of a clinical relevant RLS is not yet established. It probably depends on interindividual differences in hemodynamics that are currently not fully understood. Transesophageal echocardiography remains the gold standard for detection of a patent foramen ovale or an atrial septum defect. However, TCD with a contrast agent has been turned out as a potential method to diagnose a RLS in several studies which have been published during the last years, and a RLS other than at the atrial level may be detected only by this method. Furthermore, the VM can be applied more comfortably and more reliably during Doppler examination than during transesophageal echocardiography.

Background and Purpose-Transesophageal echocardiography (TEE) has detected a high prevalence of patent foramen ovale (PFO) in stroke patients, but the clinical implications of the distinctive characteristics of this patency are still a matter of debate. Methods-We studied 350 patients with acute ischemic stroke or transient ischemic attack (TIA) within 1 week of admission. Of these, 101 (29%) were identified by contrast TEE to have a PFO; 86 patients (25%) were cryptogenic stroke patients, and 163 were excluded because of the presence of a definite or possible arterial or clinical evidence of a source of emboli or small-vessel disease. Thirteen PFO subjects without a history of embolism were designated as the control group. All PFO and cryptogenic stroke patients were followed up by neurological visits. Results-Compared with controls, PFO patients with acute stroke or TIA more frequently presented with a right-to-left shunt at rest and a higher membrane mobility (PϽ0.05). Patients with these characteristics were considered to be at high risk. During a median follow-up period of 31 months (range, 4 to 58 months), 8 PFO and 18 cryptogenic stroke patients experienced recurrent cerebrovascular events. The cumulative estimate of risk of cerebrovascular event recurrence at 3 years was 4.3% (95% confidence interval [CI], 0% to 10.2%) for "low-risk" PFO patients, 12.5% (95% CI, 0% to 26.1%) for "high-risk" PFO patients, and 16.3% (95% CI, 7.2% to 25.4%) for cryptogenic stroke patients (high-risk PFO versus low-risk PFO, Pϭ0.05). Conclusions-The association of right-to-left shunting at rest and high membrane mobility, as detected by contrast TEE, seems to identify PFO patients with cerebrovascular ischemic events who are at higher risk for recurrent brain embolism.

We compared digital intra-arterial angiography and transcranial Doppler sonography in acute cerebral ischemia as part of a wider study on a continuous series of 48 patients with acute focal cerebral ischemia in the carotid territory, observed within 4 hours of the onset of symptoms. T he high frequency of acute intracranial occlusion and the therapeutic use of active thrombolytic agents stress the need to monitor the patency of intracranial cerebral arteries in acute ischemic strokes.1 Noninvasive exams should represent the first choice in detecting the occurrence of intracranial arterial occlusions in the very early phase and in following their natural course and responsiveness to therapies.2 The aim of this report is to validate transcranial Doppler (TCD) with respect to cerebral angiography, when both are performed within a short interval, and to define some guidelines for interpretation of TCD findings in acute cerebral ischemia. Subjects and MethodsWe examined 48 patients (22 men, 26 women; mean age±SD, 66.2±9.7years) who had focal cerebral deficits of acute onset due to hemispheric cerebral ischemia. Clinical observation occurred within 4 hours of the onset of the stroke, and within the following 2 hours, all patients underwent a computed tomography (CT) scan, TCD, and intraarterial cerebral angiography. The last two tests were scored independently and blindly.

TCD examination offers an easy and reliable way of monitoring MCA reopening and might be useful to identify subgroups of patients who may benefit most from pharmacological reperfusion.