Grading Right-to-Left Shunt With Transforaminal Doppler: A Valid Approach in Patients With Cryptogenic Stroke.

Background And Purpose: Right-to-left shunt (RLS), usually related to a patent foramen ovale (PFO), is an important cause of cryptogenic stroke (CS) in young patients. Transcranial Doppler (TCD) with an agitated saline bubble study is a highly sensitive modality for RLS diagnosis using a transtemporal approach (TTD). However, a minority of patients have insufficient temporal bone windows.