Detection of Cardiac Right-to-Left Shunts by Contrast-Enhanced Harmonic Carotid Duplex Sonography

Abstract

Objective Paradoxical embolization by cardiac right‐to‐left shunts (RLS) is increasingly recognized as an important factor for embolic stroke. Contrast‐enhanced transcranial Doppler sonography (ce‐TCDS) is an established diagnostic tool for RLS detection but is frequently limited because of an inadequate temporal acoustic bone window. The purpose of this study was to determine whether extracranial sonography (ECS) using harmonic frequencies improves detection of RLS. Methods Extracranial color duplex sonography using harmonic frequencies enables visualization of even single ultrasound contrast agent microbubbles because of oscillation. Patients with stroke and positive RLS findings on transesophageal echocardiography underwent a simultaneous extracranial and transcranial sonographic examination of the proximal common carotid artery (CCA) and middle cerebral artery (MCA) on the same side. A Valsalva strain was performed for 10 seconds after intravenous bolus injection of a galactose‐based nontranspulmonary contrast agent. The B‐mode frame sequences of the transverse plane of the CCA obtained by harmonic ECS and the ce‐TCDS recordings of high‐intensity transient signals from the MCA were analyzed offline. Results In all patients with RLS, the shunts could be identified by harmonic ECS. A close correlation could be seen between the count of visualized microbubbles in the CCA and the number of high‐intensity transient signals detected on ce‐TCDS in the ipsilateral MCA. Conclusions The results of this study indicate that contrast‐enhanced ultrasound harmonic imaging of the CCA using a Valsalva strain might be an optional screening tool for detection of cardiac RLS in patients with insufficient acoustic bone windows.

Carotid ultrasound for pulmonary arteriovenous malformation screening

“…No striking difference was noticed between the two sides, and therefore this parameter is not included. In accordance, Draganski et al [24] report that in the detection of cardiac right-to-left shunts, no significant differences between high-intensity transient signal counts in the right and left middle cerebral arteries were found.…”

Guidelines for the Echocardiographic Assessment of Atrial Septal Defect and Patent Foramen Ovale: From the American Society of Echocardiography and Society for Cardiac Angiography and Interventions

“…A, anterior; Ao, aorta; C, catheter; CS, coronary sinus; L, left; LPV, left pulmonary vein; P, posterior; R, right; RAA, right atrial appendage; RPA, right pulmonary artery; S, superior; S1, septum primum; S2, septum secundum; TV, tricuspid valve. Reproduced with permission from Roberson et al 72 the atrial septum. This should be performed before and after device placement, again to evaluate for mitral regurgitation and tricuspid regurgitation after device placement.…”

“…52,61,63,[68][69][70][71][72][73][74][75] Contrast echocardiography and contrast TCD is discussed further in sections on Assessment of Shunting; Techniques, Standards, and Characterization Visualization of Shunting: TTE and TEE; and Transcranial Doppler Detection/Grading of Shunting. Table 1 summarizes the recommended general imaging approach to atrial septal abnormalities stratified by the patient characteristics, imaging modality, and intended application (e.g., diagnosis, procedure selection or guidance, follow-up).…”

Diagnosis of Right-to-Left Shunt: Possible Alternative Approaches

“…This method was already described by Draganski et al in 2005 5 but did not find its way into broad clinical practice. Performance and visualization of highintensity transient signals using contrast-enhanced harmonic carotid duplex and Doppler sonography are simple.…”