title: Normal renal artery spectral Doppler waveform: a closer look.
abstract: OBJECTIVE
  To characterize the spectral Doppler tracing of the normal renal artery.
  
  
  METHODS
  Doppler tracings were obtained from a phantom of a vessel with variable compliance and from the kidneys of 15 healthy volunteers.
  
  
  RESULTS
  In the phantom, vascular compliance had the following effects on systolic flow velocity patterns: low compliance, little change in the sharp appearance of the systolic component of the transmitted pulse; mildly increased compliance, down-stream dampening of early systolic acceleration (ESA) with the appearance of a sharp early systolic transmitted peak and of a more rounded late systolic compliance peak; high compliance, delayed and diminished transmitted peak that eventually disappeared within the enlarging down-stream compliance peak. Healthy subjects with compliant vessels had greater ESA and more frequently visualized early systolic peaks in the renal hilum than in the renal sinus.
  
  
  CONCLUSIONS
  Absence of a discrete early systolic peak is a normal finding in young patients, especially in the more distal interlobar arteries. Loss of the early systolic peak may be explained on the basis of vascular compliance.
authors.affiliation: Department of Radiology, Jefferson Medical College of Thomas Jefferson University Hospital, Philadelphia, PA 19107-5244, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Halpern
authors.forename: C R
authors.initials: CR
authors.lastname: Deane
authors.forename: L
authors.initials: L
authors.lastname: Needleman
authors.forename: D A
authors.initials: DA
authors.lastname: Merton
authors.forename: S A
authors.initials: SA
authors.lastname: East
mesh_terms: D000054:Acceleration; D000328:Adult; D001783:Blood Flow Velocity; D006801:Humans; D008961:Models, Structural; D015588:Observer Variation; D011673:Pulsatile Flow; D011674:Pulse; D012039:Regional Blood Flow; D012077:Renal Artery / Q000000981:diagnostic imaging*; D016037:Single-Blind Method; D013599:Systole; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance