title: Left atrial compression and the mechanism of exercise impairment in patients with a large hiatal hernia.
abstract: OBJECTIVE
  The purpose of this study was to determine the association between cardiac compression and exercise impairment in patients with a large hiatal hernia (HH).
  
  
  BACKGROUND
  Dyspnea and exercise impairment are common symptoms of a large HH with unknown pathophysiology. Studies evaluating the contribution of cardiac compression to the pathogenesis of these symptoms have not been performed.
  
  
  METHODS
  We collected clinical data from a consecutive series of 30 patients prospectively evaluated with resting and stress echocardiography, cardiac computed tomography, and respiratory function testing before and after laparoscopic HH repair. Left atrial (LA), inferior pulmonary vein, and coronary sinus compression was analyzed in relation to exercise capacity (metabolic equivalents [METs] achieved on Bruce treadmill protocol).
  
  
  RESULTS
  Exertional dyspnea was present in 25 of 30 patients (83%) despite normal mean baseline respiratory function. Moderate to severe LA compression was qualitatively present in 23 of 30 patients (77%) on computed tomography. Right and left inferior pulmonary vein and coronary sinus compression was present in 11 of 30 (37%), 12 of 30 (40%), and 26 of 30 (87%) patients, respectively. Post-operatively, New York Heart Association functional class and exercise capacity improved significantly (number of patients in New York Heart Association functional classes I, II, III, and IV: 6, 11, 11, and 2 vs. 26, 4, 0, and 0, respectively, p < 0.001; METs [percentage predicted]: 75 ± 24% vs. 112 ± 23%, p < 0.001) and resolution of cardiac compression was observed. Absolute change in LA diameter on the echocardiogram was the only independent cardiorespiratory predictor of exercise capacity improvement post-operatively (p = 0.006).
  
  
  CONCLUSIONS
  We demonstrate, for the first time, marked exercise impairment and cardiac compression in patients with a large HH and normal respiratory function. After HH repair, exercise capacity improves significantly and correlates with resolution of LA compression.
authors.affiliation: Department of Cardiology, Concord Repatriation General Hospital, The University of Sydney, Concord, NSW 2139, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Naoum
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Falk
authors.forename: Austin C C
authors.initials: AC
authors.lastname: Ng
authors.forename: Tony
authors.initials: T
authors.lastname: Lu
authors.forename: Lloyd
authors.initials: L
authors.lastname: Ridley
authors.forename: Alvin J
authors.initials: AJ
authors.lastname: Ing
authors.forename: Leonard
authors.initials: L
authors.lastname: Kritharides
authors.forename: John
authors.initials: J
authors.lastname: Yiannikas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016279:Atrial Function, Left; D004417:Dyspnea / Q000209:etiology; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006325:Heart Atria / Q000503:physiopathology*; D006331:Heart Diseases / Q000209:etiology / Q000503:physiopathology*; D006551:Hernia, Hiatal / Q000150:complications* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged