The Need to Quantify Right-to-Left Shunt in Acute Ischemic Stroke

Abstract

Background and Purpose-Although right-to-left shunt (RLSh) has been reported to be significantly more frequent in young stroke patients with cryptogenic stroke, its relevance in a nonselected population of acute ischemic stroke is not well known. The aim of this study was to determine the importance of the RLSh magnitude as a risk factor for stroke in nonselected patients. Methods-Two hundred eight patients hospitalized consecutively with transient ischemic attack or acute cerebral infarction and 100 healthy control subjects were studied. Transcranial Doppler ultrasonography (TCD) was performed in both middle cerebral arteries (MCAs) after intravenous application of agitated saline solution. The magnitude of RLSh was quantified by counting the number of signals in 1 MCA during a Valsalva maneuver. RLSh was classified as "no shunt," "small" (Ͻ10 signals), and "large" (Ͼ10 signals), with the latter including the "shower" (Ͼ25 signals) and "curtain" (uncountable signals) patterns. Extensive investigations, including contrast transesophageal echocardiography, were carried out on patients diagnosed as suffering from stroke of an uncertain etiology. The importance of RLSh for stroke was assessed by logistic regression analysis. Results-Contrast TCD detected a large RLSh in 40 (19.7%) patients and in 21 (21%) control subjects, all with cardiac RLSh characteristics. A large RLSh was present in 4.7% of atherothrombotic strokes, 10.5% of cardioembolic strokes, 15.4% of lacunar strokes, and 45.3% of cryptogenic strokes (PϽ0.001). Although the overall frequency of RLSh was not significantly different between patients and control subjects, the detection of curtain or shower patterns by contrast TCD was associated with a higher risk of stroke (odds ratio , 3.5; 95% confidence interval, 1.29 to 9.87), particularly with cryptogenic stroke (odds ratio, 12.4; 95% confidence interval, 4.08 to 38.09) after adjustment for concomitant vascular risk factors. Conclusions-It is essential to quantify RLSh by contrast TCD during the Valsalva maneuver given that only those with shower and curtain patterns are associated with a higher risk of ischemic stroke in a nonselected population. (Stroke. 1998;29:1322-1328.)Key Words: echocardiography, transesophageal Ⅲ foramen ovale, patent Ⅲ stroke, acute Ⅲ ultrasonography, Doppler, transcranial I schemic strokes represent the third greatest cause of death and the greatest cause of functional incapacity in the western world. Despite exhaustive investigations, the origin of ischemic strokes is undetermined in 40% of cases according to conventional etiologic criteria, 1 and this is even higher in young stroke patients. PFO has been suggested as a potential source of paradoxical embolism, 2-15 but this has been questioned by some experts. 16 -20 Most authors agree that there is greater prevalence of RLSh in ischemic stroke of undetermined etiology, [2][3][4][5]7,9,11,12,19 although most studies have been carried out using only TEE [2][3][4][5][12][13][14][15][16][17]19,21 or in relatively small group...

Recurrent cerebrovascular ischaemic events in patients with interatrial septal abnormalities: a follow-up study

“…A number of reports have recently emphasised the size of the right to left shunt as the crucial factor for paradoxical embolism in stroke patients [15][16][17][18].…”

“…According to our previous work [13] and to other Authors [15][16][17], the entity of the right-left shunt was defined "small" if less than 20 microbubbles appeared in the left atrium upon release of a Valsalva manoeuvre and "large" if at least 20 microbubbles appeared after Valsalva or if a right to left shunt was evident at rest. An ASA was diagnosed when the atrial septum extended at least for 11 mm either into the left or the right atrium or both.…”

Contrast Transcranial Doppler Ultrasound in the Detection of Right-to-Left Shunts

“…Once conclusive recommendations on the treatment of RLS patients are available, the importance of contrast TCD may further increase (1) because of its ability to detect RLS not noted during TEE and (2) because of the possibility of quantifying shunts by the number of MES detected. 29 …”

Migraine, patent foramen ovale and migraine triggers

“…Perhaps the most relevant aspect has been the elevated frequency of PFO in stroke of undetermined cause [4,[13][14][15] and its recurrences [16,17]. In fact, an association between stroke, PFO and migraine has been reported [5,18,19].…”