title: Lvad pump speed increase is associated with increased peak exercise cardiac output and vo2, postponed anaerobic threshold and improved ventilatory efficiency.
abstract: BACKGROUND
  Peak exercise cardiac output (CO) increase is associated with an increase of peak oxygen uptake (VO2), provided that arteriovenous O2difference [Δ(Ca-Cv)O2] does not decrease. At anaerobic threshold, VO2, is related to CO. We tested the hypothesis that, in heart failure (HF) patients with left ventricular assistance device (LVAD), an acute increase of CO obtained through changes in LVAD pump speed is associated with peak exercise and anaerobic threshold VO2increase.
  
  
  METHODS
  Fifteen of 20 patients bearing LVAD (Jarvik 2000) enrolled in the study successfully performed peak exercise evaluation. All patients had severe HF as shown by clinical evaluation, laboratory tests, echocardiography, spirometry with alveolar-capillary diffusion, and maximal cardiopulmonary exercise testing (CPET). CPETs with non-invasive CO measurements at rest and peak exercise were done on 2days at LVAD pump speed set randomly at 2 and 4.
  
  
  RESULTS
  Increasing LVAD pump speed from 2 to 4 increased CO from 3.4±0.9 to 3.8±1.0L/min (ΔCO 0.4±0.6L/min, p=0.04) and from 5.3±1.3 to 5.9±1.4L/min (ΔCO 0.6±0.7L/min, p<0.01) at rest and peak exercise, respectively. Similarly, VO2increased from 788±169 to 841±152mL/min (ΔVO252±76mL/min, p=0.01) and from 568±116 to 619±124mL/min (ΔVO269±96mL/min, p=0.02) at peak exercise and at anaerobic threshold, respectively. Δ(Ca-Cv)O2did not change significantly, while ventilatory efficiency improved (VE/VCO2slope from 39.9±5.4 to 34.9±8.3, ΔVE/VCO2-5.0±6.4, p<0.01).
  
  
  CONCLUSIONS
  In HF, an increase in CO with a higher LVAD pump speed is associated with increased peak VO2, postponed anaerobic threshold, and improved ventilatory efficiency.
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Vignati
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Apostolo
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy; Multimedica, IRCCS, Milano, Italy.
authors.forename: Gaia
authors.initials: G
authors.lastname: Cattadori
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Farina
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy.
authors.forename: Alberico
authors.initials: A
authors.lastname: Del Torto
authors.affiliation: Artech Srl, Modena, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Scuri
authors.affiliation: Cardiac Surgery Unit, Dept. of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Gino
authors.initials: G
authors.lastname: Gerosa
authors.affiliation: Cardiac Surgery Unit, Dept. of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Tomaso
authors.initials: T
authors.lastname: Bottio
authors.affiliation: Cardiac Surgery Unit, Dept. of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Tarzia
authors.affiliation: Cardiac Surgery Unit, Dept. of Cardiac, Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
authors.forename: Jonida
authors.initials: J
authors.lastname: Bejko
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy.
authors.forename: Erminio
authors.initials: E
authors.lastname: Sisillo
authors.affiliation: Dept. of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Milano, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Nicoli
authors.affiliation: Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, "Sapienza", Rome University, Rome, Italy.
authors.forename: Susanna
authors.initials: S
authors.lastname: Sciomer
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy; Dept. of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Milano, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Alamanni
authors.affiliation: IRCCS SDN, Institute of Research, Naples, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Paolillo
authors.affiliation: Centro Cardiologico Monzino, IRCCS, Milan, Italy; Dept. of Clinical Sciences and Community Health, Cardiovascular Section, University of Milano, Milano, Italy. Electronic address: piergiuseppe.agostoni@unimi.it.
authors.forename: Piergiuseppe
authors.initials: P
authors.lastname: Agostoni
mesh_terms: D015308:Anaerobic Threshold / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006353:Heart-Assist Devices; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology
keywords: Cardiac output; Exercise testing; Heart failure; LVAD