title: Validation study of Doppler-derived transmitral valve gradients compared to near simultaneously obtained directly measured catheter gradients immediately after mitral valve repair surgery.
abstract: OBJECTIVE
  To evaluate the accuracy of Doppler-derived transmitral valve gradients immediately after mitral valve repair by comparing them with near simultaneously obtained direct catheter gradients.
  
  
  METHODS
  A prospective study.
  
  
  METHODS
  A tertiary care medical center.
  
  
  METHODS
  Twenty elective adult surgical patients presenting for mitral valve repair surgery.
  
  
  METHODS
  Mitral valve surgery proceeded in standard fashion except for the use of a smaller than usual left ventricular vent catheter (Medtronic DLP 10 French left heart vent catheter). After completion of the mitral valve repair and subsequent cardiac de-airing, the patient was weaned from cardiopulmonary bypass. Immediately after separation, the study period began. Near simultaneous transmitral Doppler gradients were obtained with directly measured catheter gradients via the vent catheter.
  
  
  RESULTS
  While the mean peak gradient difference of 1.1 mmHg was small (p-value 0.18, 95% CI: -0.54 to 2.73 mmHg), the correlation between Doppler and catheter gradient measurements (Pearson correlation coefficient r = 0.54, p = 0.055) only approached statistical significance due to the large variance associated with the small sample size. In all patients with a peak gradient greater than 10 mmHg (4 of the 20 patients), overestimation of catheter gradients by Doppler occurred, with two showing a 62% to 73% discrepancy. In these two cases, there was also evidence for elevated left ventricular end-diastolic pressure (LVEDP) along with high transmitral blood flow velocities.
  
  
  CONCLUSIONS
  Doppler-derived transmitral gradients provide a simple, safe, and reliable measure of the true physiologic transmitral valve gradient. At the same time, it is important to recognize that significant Doppler over-estimation of catheter gradients may occur in patients with elevated Doppler transmitral velocities. The causes of these overestimations are unknown. They may be related to technical recording errors. They may also be related to an inherent weakness in Doppler technology--its inability to account for any distal recovery of pressure, which in a select group of patients could be significant.
authors.affiliation: Department of Anesthesia and Critical Care, Hospital of the University of Pennsylvania, Philadelphia, USA. vernickw@uphs.upenn.edu
authors.forename: William J
authors.initials: WJ
authors.lastname: Vernick
authors.forename: E Andrew
authors.initials: EA
authors.lastname: Ochroch
authors.forename: Jiri
authors.initials: J
authors.lastname: Horak
authors.forename: Mary
authors.initials: M
authors.lastname: Hammond
authors.forename: W Clark
authors.initials: WC
authors.lastname: Hargrove
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D006328:Cardiac Catheterization / Q000379:methods*; D017548:Echocardiography, Transesophageal / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies