title: Changes in ocular blood flow velocities during external counterpulsation in healthy volunteers and patients with atherosclerosis.
abstract: BACKGROUND
  External counterpulsation (ECP) is a new noninvasive means of augmenting organ perfusion by applying ECG-triggered diastolic pressure to the vascular bed of the lower limbs. In this study, effects of ECP on changes of ocular blood flow velocities were studied.
  
  
  METHODS
  Mean, systolic and diastolic flow velocities of the ophthalmic artery were measured by Doppler sonography before and during ECP. Twelve healthy volunteers (age 31.3+/-4.3 years) and 12 patients with severe atherosclerosis (inclusion criteria: two atherosclerotic risk factors, at least one severe coronary stenosis, age 62.1+/-5.3 years) were included in the study.
  
  
  RESULTS
  In healthy subjects, ECP changed diastolic flow velocity of the ophthalmic artery nonsignificantly from 21.6+/-7.7 to 23.7+/-10.5 cm/s. Systolic flow velocity decreased significantly from 36.1+/-13.6 to 28.9+/-10.2 cm/s (P<0.01). Mean flow velocity changed nonsignificantly from 28.1+/-9.4 to 26.5+/-9.9 cm/s. In atherosclerotic patients, mean flow velocity increased significantly from 26.3+/-11.4 to 29.3+/-11.2 cm/s (P<0.001), which was caused by significant diastolic flow augmentation from 19.7+/-9.1 to 23.9+/-9.7 cm/s (P<0.001). Systolic flow velocity was not changed significantly (from 34.2+/-12.8 to 32.6+/-11.8 cm/s).
  
  
  CONCLUSIONS
  No significant change of mean blood flow velocity in the ophthalmic artery was found in young healthy subjects. In elderly patients with atherosclerosis, ECP significantly increased blood flow velocity in the ophthalmic artery by 11.4%. This may indicate an ocular perfusion benefit in these patients as a result of ECP and could also explain the increase of perfusion found in patients with retinal ischemia after ECP.
authors.affiliation: II. Medical Clinic (Cardiology, Angiology), Friedrich-Alexander-University, Erlangen-Nuremberg, Erlangen, Germany. Dierk.Werner@nexgo.de
authors.forename: D
authors.initials: D
authors.lastname: Werner
authors.forename: G
authors.initials: G
authors.lastname: Michelson
authors.forename: J
authors.initials: J
authors.lastname: Harazny
authors.forename: F
authors.initials: F
authors.lastname: Michalk
authors.forename: J U
authors.initials: JU
authors.lastname: Voigt
authors.forename: W G
authors.initials: WG
authors.lastname: Daniel
mesh_terms: D000328:Adult; D001161:Arteriosclerosis / Q000503:physiopathology*; D001783:Blood Flow Velocity; D015908:Counterpulsation; D005123:Eye / Q000098:blood supply; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009880:Ophthalmic Artery / Q000503:physiopathology*; D018608:Ultrasonography, Doppler