title: How much of the intraaortic balloon volume is displaced toward the coronary circulation?
abstract: OBJECTIVE
  During intraaortic balloon inflation, blood volume is displaced toward the heart (V(tip)), traveling retrograde in the descending aorta, passing by the arch vessels, reaching the aortic root (V(root)), and eventually perfusing the coronary circulation (V(cor)). V(cor) leads to coronary flow augmentation, one of the main benefits of the intraaortic balloon pump. The aim of this study was to assess V(root) and V(cor) in vivo and in vitro, respectively.
  
  
  METHODS
  During intraaortic balloon inflation, V(root) was obtained by integrating over time the aortic root flow signals measured in 10 patients with intraaortic balloon assistance frequencies of 1:1 and 1:2. In a mock circulation system, flow measurements were recorded simultaneously upstream of the intraaortic balloon tip and at each of the arch and coronary branches of a silicone aorta during 1:1 and 1:2 intraaortic balloon support. Integration over time of the flow signals during inflation yielded V(cor) and the distribution of V(tip).
  
  
  RESULTS
  In patients, V(root) was 6.4% +/- 4.8% of the intraaortic balloon volume during 1:1 assistance and 10.0% +/- 5.0% during 1:2 assistance. In vitro and with an artificial heart simulating the native heart, V(cor) was smaller, 3.7% and 3.8%, respectively. The distribution of V(tip) in vitro varied, with less volume displaced toward the arch and coronary branches and more volume stored in the compliant aortic wall when the artificial heart was not operating.
  
  
  CONCLUSIONS
  The blood volume displaced toward the coronary circulation as the result of intraaortic balloon inflation is a small percentage of the nominal intraaortic balloon volume. Although small, this percentage is still a significant fraction of baseline coronary flow.
authors.affiliation: Brunel Institute for Bioengineering, Brunel University, Middlesex, United Kingdom.
authors.forename: Christina
authors.initials: C
authors.lastname: Kolyva
authors.forename: George M
authors.initials: GM
authors.lastname: Pantalos
authors.forename: John R
authors.initials: JR
authors.lastname: Pepper
authors.forename: Ashraf W
authors.initials: AW
authors.lastname: Khir
mesh_terms: D001011:Aorta / Q000503:physiopathology*; D001794:Blood Pressure; D001810:Blood Volume; D003187:Compliance; D003198:Computer Simulation; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D007423:Intra-Aortic Balloon Pumping; D008297:Male; D008875:Middle Aged; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D012039:Regional Blood Flow; D013997:Time Factors