title: Cardio-respiratory responses of the 6-minute walk test in patients with refractory heart failure during the preoperative period for heart transplant surgery.
abstract: BACKGROUND
  The six-minute walk test (6MWT) has been used to assess functional capacity, clinical status and prognosis. There are a very few descriptions in the literature on the safety and metabolic impact of the test, especially in patients with severe heart failure, awaiting cardiac transplantation.
  
  
  OBJECTIVE
  The aim of the present study was to assess the cardiovascular responses and correlate the performance on the 6MWT with clinical status.
  
  
  METHODS
  From 15 initial candidates, twelve patients (10 males) aged 52 +/- 8 years were submitted to a comprehensive clinical evaluation. The patients performed the 6MWT with electrocardiographic and perceived exertion monitoring in addition to determination of blood lactate concentration. Patients were followed up for 12 months.
  
  
  RESULTS
  The patients walked 399.4 +/- 122.5 meters, reaching a perceived exertion (PE) of 14.3 +/- 1.5 and an increase of 34% in resting heart rate. Two patients exhibited a greater severity of arrhythmia prior to the 6MWT, which did not increase during exertion. Four patients exhibited a significant increase in blood lactate levels (>5 mmol/dL) and three interrupted the test prematurely. The distance walked (D) revealed a correlation with the ejection fraction (%) and functional classification (NYHA). After 12 months of follow up, three patients died and seven were re-hospitalized due to heart failure decompensation.
  
  
  CONCLUSIONS
  Clinical and electrocardiographic behavior suggests that the 6MWT is safe, but may be considered of high intensity for some patients with severe heart failure. Variables related to the performance on the 6MWT may be associated to worsening clinical status in this population.
authors.affiliation: Physiotherapy Division, Faculty of Ceilândia, University of Brasília, UnB, Brasília, DF Brazil. ciprianeft@uol.com.br
authors.forename: Cipriano
authors.initials: C
authors.lastname: Gerson
authors.forename: Graziella França
authors.initials: GF
authors.lastname: Bernardelli
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Luis Vicente Franco
authors.initials: LV
authors.lastname: Oliveira
authors.forename: Francisco
authors.initials: F
authors.lastname: Valdez
authors.forename: João Nelson Rodrigues
authors.initials: JN
authors.lastname: Branco
mesh_terms: D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000503:physiopathology*; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D013997:Time Factors