title: Vascular pulsatility in patients with a pulsatile- or continuous-flow ventricular assist device.
abstract: OBJECTIVE
  We sought to investigate differences in indices of pulsatility between patients with normal ventricular function and patients with heart failure studied at the time of implantation with continuous-flow or pulsatile-flow left ventricular assist devices.
  
  
  METHODS
  Eight patients with normal ventricular function and 22 patients with heart failure were studied. A high-fidelity aortic and left ventricular pressure catheter was inserted retrograde through the aortic valve into the left ventricle, and transit-time flow probes were placed on the aorta and device outflow graft. Hemodynamic waveforms were recorded at native heart rate before cardiopulmonary bypass and over a range of device flow rates controlled by adjusting beat rate or rpm. These data were used to calculate vascular input impedance and 2 indices of vascular pulsatility: energy-equivalent pressure and surplus hemodynamic energy.
  
  
  RESULTS
  At low support levels, pulsatile support restored surplus hemodynamic energy to within 2.5% of normal values, whereas continuous support diminished surplus energy by more than 93%. At high support levels, pulsatile support augmented surplus energy by 49% over normal values, whereas continuous support further diminished surplus energy by 97%. Pulsatile support diminished vascular impedance from baseline failure values, whereas continuous support increased impedance. Vascular impedances at baseline for patients undergoing pulsatile and continuous support and during pulsatile support revealed normal vascular compliance, whereas impedance during continuous support indicated a loss of compliance (or "stiffening") of the vasculature.
  
  
  CONCLUSIONS
  These results suggest that selection of device type and flow rate can influence vascular pulsatility and input impedance, which might affect clinical outcomes.
authors.affiliation: Cardiovascular Innovation Institute, University of Louisville, Louisville, Ky 40202, USA.
authors.forename: Adam R
authors.initials: AR
authors.lastname: Travis
authors.forename: Guruprasad A
authors.initials: GA
authors.lastname: Giridharan
authors.forename: George M
authors.initials: GM
authors.lastname: Pantalos
authors.forename: Robert D
authors.initials: RD
authors.lastname: Dowling
authors.forename: Sumanth D
authors.initials: SD
authors.lastname: Prabhu
authors.forename: Mark S
authors.initials: MS
authors.lastname: Slaughter
authors.forename: Mike
authors.initials: M
authors.lastname: Sobieski
authors.forename: Akif
authors.initials: A
authors.lastname: Undar
authors.forename: David J
authors.initials: DJ
authors.lastname: Farrar
authors.forename: Steven C
authors.initials: SC
authors.lastname: Koenig
mesh_terms: D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity; D002315:Cardiopulmonary Bypass / Q000009:adverse effects / Q000379:methods; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*; D006334:Heart Function Tests; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D011673:Pulsatile Flow / Q000502:physiology*; D012016:Reference Values; D018570:Risk Assessment; D013318:Stroke Volume; D015996:Survival Rate; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000401:mortality / Q000601:surgery*