Detection of Right‐to‐Left Shunts may be Associated with Body Size

BACKGROUND AND PURPOSE The aim of this study was to investigate whether physiological factors, including body mass index (BMI), are associated with detection of right-to-left shunt (RLS) by contrast transcranial Doppler ultrasonography (c-TCD). METHODS After prospective c-TCD for stroke patients, we compared clinical backgrounds between patients with positive and negative results for RLS. After counting microembolic signals (MES), RLS were functionally graded as follows (grade 0 = 0 MES, grade I = 1-10 MES, grade II = 11-30 MES, grade III = 31-100 MES if countable, grade IV = over 100 MES or uncountable like a shower. RESULTS Subjects comprised 584 patients (203 men, 381 women) with a mean age of 67.9 ± 11.1 years. RLS was detected in 134 of 584 patients (23%). In univariate analysis, mean BMI was 22.1 in patients with RLS and 23.3 in those without RLS (P= .004). Mean BMI in concordance with RLS grade gradually decreased (grade 0; 22.7, grade I; 20.8, grade II; 20.1, grade III; 19.6, P= .001). After performing the Valsalva maneuver, mean BMI in concordance with RLS grade linearly increased (grade I; 20.6, grade II; 23.2, grade III; 24.8, grade IV; 25.8, P < .001). CONCLUSION Although smaller body size may be associated with detection of RLS, a patient with significant RLS (grade III or IV) had larger body.