title: Transthoracic echocardiography using second harmonic imaging with Valsalva manoeuvre for the detection of right to left shunts.
abstract: OBJECTIVE
  To assess transthoracic echocardiography (TTE) using second harmonic imaging with Valsalva manoeuvre compared to transesophageal echocardiography (TEE) for the diagnosis of right to left cardiac and pulmonary shunts.
  
  
  RESULTS
  One hundred and ten patients referred for TEE underwent TTE with bubble contrast. Bubbles in the left atrium within three cardiac cycles were considered diagnostic for a patent foramen ovale (PFO) and later as a pulmonary shunt. Greater than 20 bubbles in the left atrium was considered a large shunt and less than 20 a small shunt. TEE was performed immediately afterwards and read blinded to the TTE results. Pick-up rates were similar with 19 TEE positive (13 PFO) and 18 TTE positive (14 PFO) patients. There were five TEE positive/TTE negative cases who had significantly poorer TTE image quality score (2.7 +/- 0.8 vs 1.9 +/- 0.6, p < 0.05). There were six TEE negative/TTE positive cases, two cases requiring Valsalva manoeuvre to become positive. The Valsalva manoeuvre significantly increased the number of bubbles shunting (10 +/- 11 vs 20 +/- 19, p < 0.005).
  
  
  CONCLUSIONS
  TTE with Valsalva manoeuvre is as good as TEE in diagnosing shunts. Valsalva manoeuvre increases the size of shunt. Both techniques produce false negative results.
authors.affiliation: Department of Cardiology, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
authors.forename: N R A
authors.initials: NR
authors.lastname: Clarke
authors.forename: J
authors.initials: J
authors.lastname: Timperley
authors.forename: A D
authors.initials: AD
authors.lastname: Kelion
authors.forename: A P
authors.initials: AP
authors.lastname: Banning
mesh_terms: D000368:Aged; D002302:Cardiac Output / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology; D003328:Coronary Thrombosis / Q000000981:diagnostic imaging; D004452:Echocardiography / Q000379:methods*; D019320:Embolism, Paradoxical / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005260:Female; D006344:Heart Septal Defects, Atrial / Q000175:diagnosis / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging; D012965:Sodium Chloride; D014636:Valsalva Maneuver
chemical_list: D012965:Sodium Chloride