title: Real-time MR imaging of aortic flow: influence of breathing on left ventricular stroke volume in chronic obstructive pulmonary disease.
abstract: OBJECTIVE
  To assess real-time changes of left ventricular stroke volume (SV) in relation to the breathing pattern in healthy subjects and in patients with chronic obstructive pulmonary disease (COPD).
  
  
  METHODS
  Real-time magnetic resonance (MR) imaging flow measurements were performed in the ascending aorta of 10 healthy volunteers and nine patients with severe COPD. Breathing maneuvers were registered with an abdominal pressure belt, which was synchronized to the electrocardiographic signal and the flow measurement. Healthy subjects performed normal breathing, deep breathing, and the Valsalva maneuver. Patients with COPD performed spontaneous breathing. Paired two-tailed Student t tests were used in healthy volunteers to assess significant SV differences between normal breathing and deep breathing or the Valsalva maneuver. The results of measurements in the patients with COPD were compared with the results during normal breathing in healthy subjects with the unpaired two-tailed Student t test.
  
  
  RESULTS
  In healthy subjects, SV decreased during inspiration and increased during expiration (r2 = 0.78, P <.05). When compared with the SV during normal breathing, mean SV did not change during deep breathing but declined during the Valsalva maneuver (P <.05). The difference between minimal and maximal SVs (ie, SV range) increased because of deep breathing or the Valsalva maneuver (P <.05). In normal and deep breathing, velocity of SV elevation and velocity of SV decrease were equal (which resulted in a ratio of 1), whereas during the Valsalva maneuver, this value increased (P <.05). Spontaneous breathing in COPD resulted in SV changes (P <.05) similar to those observed in healthy subjects who performed the Valsalva maneuver.
  
  
  CONCLUSIONS
  Real-time MR imaging of aortic flow reveals physiologic flow alterations, which are dependent on variations in the breathing pattern.
authors.affiliation: Department of Radiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, the Netherlands.
authors.forename: Rik J
authors.initials: RJ
authors.lastname: van den Hout
authors.forename: Hildo J
authors.initials: HJ
authors.lastname: Lamb
authors.forename: Joost G
authors.initials: JG
authors.lastname: van den Aardweg
authors.forename: Robert
authors.initials: R
authors.lastname: Schot
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van der Wall
authors.forename: Jeroen J
authors.initials: JJ
authors.lastname: Bax
authors.forename: Albert
authors.initials: A
authors.lastname: de Roos
mesh_terms: D000328:Adult; D000368:Aged; D001011:Aorta / Q000503:physiopathology*; D001783:Blood Flow Velocity; D004562:Electrocardiography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012119:Respiration; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume; D014636:Valsalva Maneuver; D016277:Ventricular Function, Left