title: Effect of exercise and pump speed modulation on invasive hemodynamics in patients with centrifugal continuous-flow left ventricular assist devices.
abstract: BACKGROUND
  Continuous-flow left ventricular assist devices (CF-LVADs) improve functional capacity in patients with end-stage heart failure. Pump output can be increased by increased pump speed as well as changes in loading conditions.
  
  
  METHODS
  The effect of exercise on invasive hemodynamics was studied in two study protocols. The first examined exercise at fixed pump speed (n = 8) and the second with progressive pump speed increase (n = 11). Patients underwent simultaneous right-heart catheterization, mixed venous saturation, echocardiography and mean arterial pressure monitoring. Before exercise, a ramp speed study was performed in all patients. Patients then undertook symptom-limited supine bicycle exercise.
  
  
  RESULTS
  Upward titration of pump speed at rest (by 11.6 ± 8.6% from baseline) increased pump flow from 5.3 ± 1.0 to 6.3 ± 1.0 liters/min (18.9% increase, p < 0.001) and decreased pulmonary capillary wedge pressure (PCWP; 13.6 ± 5.4 to 8.9 ± 4.1 mm Hg, p < 0.001). Exercise increased pump flow to a similar extent as pump speed change alone (to 6.2 ± 1.0 liters/min, p < 0.001), but resulted in increased right- and left-heart filling pressures (right atrial pressure [RAP]: 16.6 ± 7.5 mm Hg, p < 0.001; PCWP 24.8 ± 6.7 mm Hg, p < 0.001). Concomitant pump speed increase with exercise enhanced the pump flow increase (to 7.0 ± 1.4 liters/min, p < 0.001) in Protocol 2, but did not alleviate the increase in pre-load (RAP: 20.5 ± 8.0 mm Hg, p = 0.07; PCWP: 26.8 ± 12.7 mm Hg; p = 0.47). Serum lactate and NT-proBNP levels increased significantly with exercise.
  
  
  CONCLUSIONS
  Pump flow increases with up-titration of pump speed and with exercise. Although increased pump speed decreases filling pressures at rest, the benefit is not seen with exercise despite concurrent up-titration of pump speed.
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney; Victor Chang Cardiac Research Institute, Sydney.
authors: Kavitha
authors: K
authors: Muthiah
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney.
authors: Desiree
authors: D
authors: Robson
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney.
authors: Roslyn
authors: R
authors: Prichard
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney.
authors: Robyn
authors: R
authors: Walker
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney.
authors: Sunil
authors: S
authors: Gupta
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney; Victor Chang Cardiac Research Institute, Sydney.
authors: Anne M
authors: AM
authors: Keogh
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney; Victor Chang Cardiac Research Institute, Sydney.
authors: Peter S
authors: PS
authors: Macdonald
authors: Ventracor Limited, Chatswood, New South Wales, Australia.
authors: John
authors: J
authors: Woodard
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney.
authors: Eugene
authors: E
authors: Kotlyar
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney.
authors: Kumud
authors: K
authors: Dhital
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney.
authors: Emily
authors: E
authors: Granger
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney.
authors: Paul
authors: P
authors: Jansz
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney.
authors: Phillip
authors: P
authors: Spratt
authors: Heart Failure and Transplant Unit, St. Vincent׳s Hospital, Sydney; Faculty of Medicine, University of New South Wales, Sydney; Victor Chang Cardiac Research Institute, Sydney. Electronic address: cshayward@stvincents.com.au.
authors: Christopher S
authors: CS
authors: Hayward
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015444:Exercise; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000601:surgery*; D006353:Heart-Assist Devices; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D055815:Young Adult
keywords: exercise; heart failure; hemodynamics; left ventricular assist device; pump speed