title: Right-to-left shunt detection sensitivity with air-saline and air-succinil gelatin transcranial Doppler.
abstract: BACKGROUND
  Air-saline transcranial Doppler is nowadays the first-choice examination to identify right-to-left shunt. To increase right-to-left shunt detection in echocardiography, cardiologists also use air-gelatin mixtures, which are more stable, more echogenic, and easier to be prepared.
  
  
  OBJECTIVE
  We assessed the sensitivity of air-gelatin compared with air-saline for transcranial Doppler right-to-left shunt detection.
  
  
  METHODS
  Air-saline transcranial Doppler, during unilateral middle cerebral artery monitoring at rest and after Valsalva maneuver, was performed in patients referred to our neurosonology laboratory for right-to-left shunt detection. The same transcranial Doppler protocol was repeated with air-gelatin. To consider transcranial Doppler positive for cardiac right-to-left shunt, at least one embolic signal had to be detected within 20″ from contrast injection. Later signals were interpreted of pulmonary origin. Trans-thoracic echocardiography was repeated with both air-saline and air-gelatin.
  
  
  RESULTS
  A total of 97 patients were enrolled; 46 had negative transcranial Doppler for cardiac right-to-left shunt with both air-saline and air-gelatin; out of these, four patients with air-saline plus two more patients with air-gelatin presented late, isolated microemboli, slightly more numerous with air-gelatin: these were interpreted as pulmonary shunts and confirmed with trans-thoracic echocardiography. In 28 patients with already early positive air-saline transcranial Doppler at rest, air-gelatin induced a marked right-to-left shunt increase, facilitating its visualization at trans-thoracic echocardiography. In 23 patients in whom air-saline transcranial Doppler was negative at rest and positive for cardiac right-to-left shunt only after Valsalva maneuver, air-gelatin was able to reveal shunt also at rest.
  
  
  CONCLUSIONS
  Air-gelatin increases right-to-left shunt detection sensitivity with transcranial Doppler in particular at rest, even in patients in whom air-saline mixture fails to identify the shunt. The choice of air-gelatin mixture should be considered for multicentric, clinical, and research trials.
authors.affiliation: Neurosonology Laboratory, Stroke Unit, Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Puledda
authors.affiliation: Neurosonology Laboratory, Stroke Unit, Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Toscano
authors.affiliation: Neurosonology Laboratory, Stroke Unit, Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Pieroni
authors.affiliation: Department of Cardiovascular and Respiratory Sciences, Sapienza University of Rome, Rome, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Veneroso
authors.affiliation: Neurosonology Laboratory, Stroke Unit, Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Di Piero
authors.affiliation: Neurosonology Laboratory, Stroke Unit, Department of Neurology and Psychiatry, Sapienza University of Rome, Rome, Italy edoardo.vicenzini@uniroma1.it.
authors.forename: Edoardo
authors.initials: E
authors.lastname: Vicenzini
mesh_terms: D000328:Adult; D000388:Air; D003287:Contrast Media; D004452:Echocardiography; D017548:Echocardiography, Transesophageal; D005780:Gelatin / Q000008:administration & dosage*; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D012680:Sensitivity and Specificity; D012965:Sodium Chloride / Q000008:administration & dosage*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*; D014636:Valsalva Maneuver; D055815:Young Adult
chemical_list: D003287:Contrast Media; D012965:Sodium Chloride; D005780:Gelatin
keywords: Transcranial Doppler; right-to-left shunt; ultrasound contrast agents