title: Exercise hemodynamics during long-term implantation of a left ventricular assist device in patients awaiting heart transplantation.
abstract: OBJECTIVE
  The goal of this study was to assess patients with end-stage heart disease after implantation of a left ventricular assist device at rest and during exercise compatible with activities of daily life.
  
  
  BACKGROUND
  Mechanical circulatory assistance with a left ventricular assist device is an accepted therapy for bridging patients with end-stage heart disease to heart transplantation and has been proposed for long-term implantation.
  
  
  METHODS
  Three patients (aged 37, 42 and 57 years) with end-stage heart failure required implantation of a pneumatically driven, asynchronous Thermedics left ventricular assist device while awaiting heart transplantation. All were assessed 1 month later during graded supine bicycle exercise (maximal work load 100 to 150 W). Detailed central hemodynamics, including continuous pulmonary artery oxygen saturation and oxygen consumption measurements, were obtained. Two of the patients also underwent upright treadmill exercise with oxygen consumption measurements.
  
  
  RESULTS
  During supine bicycle exercise, the heart rate increased from 93 +/- 37 beats/min (95% confidence interval: mean +/- t0.025 x SE) at rest to 119 +/- 54 beats/min and left ventricular assist device rate increased from 82 +/- 47 to 109 +/- 55 beats/min. Oxygen consumption increased from 3.0 +/- 0.9 to 8.7 +/- 2.9 ml oxygen/min per kg body weight. Cardiac output increased from 6.0 +/- 4.4 to 9.6 +/- 7.1 liters/min, yielding an average exercise factor of 8.5 +/- 7.7 and an exercise index of 0.83 +/- 0.61. The patients assessed during treadmill exercise achieved a maximal oxygen consumption of 14.3 and 16.7 ml of oxygen/min per kg. No thromboembolic or other complications attributable to left ventricular assist device implantation occurred during the duration of support. All patients survived orthotopic heart transplantation and are doing well.
  
  
  CONCLUSIONS
  Significant work loads compatible with activities of daily life and adequate exercise hemodynamics were demonstrated by these patients while awaiting heart transplantation. Definitive conclusions regarding the use of this device must be viewed as preliminary because only three patients were involved in this study and the failure rate may be as high as 71% (95% confidence interval of left ventricular assist device success as a bridge to transplantation 29.3% to 100%). Final conclusions regarding the safety and efficacy of the left ventricular assist device as a possible long-term circulatory support device must await results of larger multicenter trials in progress.
authors.affiliation: San Diego Cardiac Center, California 92123.
authors.forename: B E
authors.initials: BE
authors.lastname: Jaski
authors.forename: K R
authors.initials: KR
authors.lastname: Branch
authors.forename: R
authors.initials: R
authors.lastname: Adamson
authors.forename: K L
authors.initials: KL
authors.lastname: Peterson
authors.forename: J B
authors.initials: JB
authors.lastname: Gordon
authors.forename: P M
authors.initials: PM
authors.lastname: Hoagland
authors.forename: S C
authors.initials: SC
authors.lastname: Smith
authors.forename: P O
authors.initials: PO
authors.lastname: Daily
authors.forename: W P
authors.initials: WP
authors.lastname: Dembitsky
mesh_terms: D000328:Adult; D015150:Echocardiography, Doppler; D005080:Exercise Test; D006331:Heart Diseases / Q000503:physiopathology* / Q000601:surgery; D016027:Heart Transplantation; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006353:Heart-Assist Devices; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010701:Phonocardiography; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology*