Diagnosis of Right-to-Left Shunt: Possible Alternative Approaches
To the Editor:
We read with great interest the recent article by Del Sette et al1 about diagnosis of right-to-left shunt with vertebrobasilar doppler examination.
So far, neurologists used transtemporal recordings based on the manuscript by Teague and Sharma.2 The emboli detection is in fact limited by insufficient temporal bone window in 10% to 20% of stroke patients.3 A probably even greater limitation is the lack of transcranial examination expertise in local hospitals treating stroke patients.4 Unfortunately, this issue cannot be solved by a transnuchal emboli detection technique.
Recordings at the common carotid artery should be considered as a possible alternative technique. This method was already described by Draganski et al in 20055 but did not find its way into broad clinical practice. Performance and visualization of high-intensity transient signals using contrast-enhanced harmonic carotid duplex and Doppler sonography are simple. Findings in a patient with a patent foramen ovale can be seen in the Figure.
It might turn into a feasible option for local hospitals and for patients without a sufficient acoustic bone window in stroke centers if sensitivity and specificity will turn out to be comparable to the established methods.
Del Sette M, Dinia L, Rizzi D, Sugo A, Albano B, Gandolfo C. Diagnosis of right-to-left shunt with transcranial Doppler and vertebrobasilar recording. Stroke. 2007; 38: 2254–2256.
Teague SM, Sharma MK. Detection of paradoxical cerebral echo contrast embolization by transcranial Doppler ultrasound. Stroke. 1991; 22: 740–745.
Seidel G, Kaps M, Gerriets T. Potential and limitations of transcranial color-coded sonography in stroke patients. Stroke. 1995; 26: 2061–2066.
Ruland S, Gorelick PB, Schneck M, Kim D, Moore CG, Leurgans S. Acute stroke care in Illinois: a statewide assessment of diagnostic and treatment capabilities. Stroke. 2002; 33: 1334–1339.
Draganski B, Blersch W, Holmer S, Koch H, May A, Bogdahn U, Holscher T, Schlachetzki F. Detection of cardiac right-to-left shunts by contrast-enhanced harmonic carotid duplex sonography. J Ultrasound Med. 2005; 24: 1071–1076.