title: Repeat microsphere delivery for serial measurement of regional blood perfusion in the chronically instrumented, conscious canine.
abstract: BACKGROUND
  For chronic, repeat hemodynamic studies in conscious dogs, we designed and tested a chronically instrumented canine microsphere delivery model. The goals of this study were (1) to investigate the accuracy of repeated estimations of blood perfusion using fluorescent-labeled microspheres and (2) to develop and validate a chronic preparation that permits consecutive estimations in the same conscious animal over an extended protocol.
  
  
  METHODS
  Via thoracotomy, nine dogs were instrumented with left atrial appendage and aortic vascular access catheters connected to subcutaneous vascular access ports. Four animals received seven serial injections of 1.6 million 15 microm microspheres (total: 11.2 million), and five animals received 8 serial injections of 2.25 million microspheres (total: 18 million) over the course of 11 or 18 wk.
  
  
  RESULTS
  All catheters have remained bidirectionally patent during protocol for 14.9 +/- 0.8 (mean +/- SEM) wk. Sphere accumulation did not significantly alter global myocardial (P = 0.69, P = 0.25), renal (P = 0.92, P = 0.12), hepatic (P = 0.84, P = 0.32), or splenic (P = 0.33, P = 0.70) blood perfusion in either set of animals.
  
  
  CONCLUSIONS
  Catheters remained bidirectionally patent for months, did not interfere with the hemodynamic responses of the preparation, and allowed repeat percutaneous injection of microspheres and withdrawal of reference arterial blood from within conscious canines. Eight serial injections totaling 18 million microspheres over 18 weeks did not alter regional myocardial, hepatic, renal, or splenic blood flow. This dependable, chronic, percutaneous arterial access preparation provides a means for examining acute and long-term effects of pathophysiological, pharmaceutical, and environmental influences on regional arterial blood flow in conscious, large animals.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA 02215, USA. cbartoli@hsph.harvard.edu
authors.forename: Carlo R
authors.initials: CR
authors.lastname: Bartoli
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okabe
authors.forename: Ichiro
authors.initials: I
authors.lastname: Akiyama
authors.forename: Brent
authors.initials: B
authors.lastname: Coull
authors.forename: John J
authors.initials: JJ
authors.lastname: Godleski
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology*; D002408:Catheters, Indwelling; D003243:Consciousness / Q000502:physiology*; D003331:Coronary Vessels / Q000502:physiology; D004285:Dogs; D005260:Female; D007261:Infusions, Intra-Arterial / Q000295:instrumentation / Q000379:methods*; D007668:Kidney / Q000098:blood supply; D008099:Liver / Q000098:blood supply; D008863:Microspheres; D023421:Models, Animal; D012039:Regional Blood Flow / Q000502:physiology; D013154:Spleen / Q000098:blood supply; D013997:Time Factors