title: Arterial impedance in patients during intraaortic balloon counterpulsation.
abstract: BACKGROUND
  Symptomatic improvement of a patient's hemodynamic condition during intraaortic balloon counterpulsation (IABC) is considered to result largely from a reduction in afterload. Afterload can be accurately quantified by arterial input impedance measurements. Here we report the effect of IABC on arterial impedance in humans.
  
  
  METHODS
  To characterize the effects of IABC on arterial input impedance, impedance measurements were obtained using aortic annulus Doppler flow and pressure from the aortic balloon catheter. Impedance spectra were compared between the cardiac cycles preceding and following the cycle with IABC in 25 patients.
  
  
  RESULTS
  Intraaortic balloon counterpulsation increased stroke volume (23%; p = 0.001), reduced myocardial oxygen demand (11%; p = 0.02), and decreased the aortic pressure at the onset of systole (16%; p = 0.001). There was also a decrease in systemic vascular resistance (24%; p = 0.001), characteristic arterial impedance (21%; p = 0.002), and pulse wave reflection (20%; p = 0.006). Linear regression analysis showed that an increase in stroke volume was predicted only by the decrease in systemic vascular resistance (r = -0.81; p = 0.001).
  
  
  CONCLUSIONS
  The reduction in systemic vascular resistance appeared to be the major mechanism by which IABC improved cardiac pumping efficiency. This effect may result from the passive distention of the peripheral vascular bed due to the propagation of the balloon-augmented diastolic pressure through the arterial system.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Loyola University Medical Center, Maywood, Illinois 60153, USA.
authors.forename: S Y
authors.initials: SY
authors.lastname: Kim
authors.forename: D E
authors.initials: DE
authors.lastname: Euler
authors.forename: W R
authors.initials: WR
authors.lastname: Jacobs
authors.forename: A
authors.initials: A
authors.lastname: Montoya
authors.forename: H J
authors.initials: HJ
authors.lastname: Sullivan
authors.forename: V A
authors.initials: VA
authors.lastname: Lonchyna
authors.forename: R
authors.initials: R
authors.lastname: Pifarré
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D005260:Female; D006331:Heart Diseases / Q000503:physiopathology / Q000601:surgery; D006439:Hemodynamics; D006801:Humans; D007423:Intra-Aortic Balloon Pumping; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D014655:Vascular Resistance