Detecting right-to-left shunt with contrasted transcranial Doppler sonography in patients with pulmonary arteriovenous malformations

Abstract

Objective To investigate the features of right-to-left shunt (RLS) detected by contrasted transcranial Doppler sonography (cTCD) in patients with pulmonary arteriovenous malformation (PAVM). Methods All medical records of clinical assessment, contrast-enhanced chest CT and CT angiography (CTA), pulmonary angiography (PA) and cTCD using agitated saline were reviewed of eight patients with PAVM, who admitted to the Department of Neurology and Department of Interventional Radiology and Vascular Surgery of our hospital between 2008 and 2015. The diagnosis of PAVM was confirmed by chest contrast-enhanced CT, CTA and PA in all eight patients. Patients with single PAVM were defined as having a solitary PAVM, while patients with multiple PAVM were defined as having two or more PAVM. Three observation indexes were analyzed to characterize RLS demonstrated by cTCD both during normal respiration and after Valsalva maneuver (VM), including the time interval for microembolic signals (MES) appearance, MES duration and shunt volume. The degree of shunt volume was graded a four-level categorization of zero through three according to MES count in unilateral middle cerebral artery (MCA): (1) grade 0, no occurrence of MES; (2) grade 1, 1-10 MES (or 1-20 in bilateral MCA); (3) grade 2, >10 MES (or>20 in bilateral MCA), but no curtain; (4) grade 3, curtain, where a single MES can not be discriminated within the TCD spectra. Shunt volume was small for grade 1, medium for grade 2, large for grade 3. RLS was considered latent shunt if occurring only after VM and continuous shunt if during normal respiration. Results Among eight patients with PAVM, five patients experienced cerebral infarction and one patient also had artery embolism of her limbs. Six patients had single PAVM and the other two had multiple PAVM. The time interval for MES appearance was 5-11 s and MES duration was 20-60 s. Shunt volume was large in seven cases and medium in one case. All cases had continuous shunt. No significant difference was observed on the features of shunt between during normal respiration and after VM. Conclusions The features of RLS detected by cTCD of PAVM visible on contrast-enhanced chest CT, CTA and PA are rapid appearance of medium to large shunt volume and continuous shunt without significant difference between during normal respiration and after VM. Key words: Arteriovenous malformations, pulmonary artery; Ultrasonography, Doppler, transcranial; Embolism, paradoxical; Retrospective studies