title: Delayed improvement in exercise capacity with restoration of sinoatrial node response in patients after combined treatment with surgical repair for organic heart disease and the Maze procedure for atrial fibrillation.
abstract: BACKGROUND
  Although the Maze procedure successfully restores sinus rhythm in patients with heart disease and atrial fibrillation, it is still uncertain whether an addition of the Maze procedure in cardiac surgery is beneficial for exercise performance of the patients after surgery.
  
  
  RESULTS
  The Maze procedure was performed in 25 patients (age, 37 to 70 years) during valve surgery (18 patients) or closure of atrial septal defect (7 patients). A cardiopulmonary exercise test using ramp incremental protocol (15 W/min) was performed before and 1 month, 6 months, and 1 year after surgery. Sinus conversion was obtained in 23 of 25 patients 1 month after surgery. However, sinoatrial (SA) node response to exercise was attenuated by surgery: Mean heart rate (HR) was 83 +/- 13/min at rest, 94 +/- 13/min at 60 W, and 107 +/- 17/min at peak exercise. Peak oxygen uptake (PVO2) was unchanged at this period (before, 17.6 +/- 4.5 mL.min-1.kg-1; 1 month after, 17.5 +/- 4.2 mL.min-1.kg-1). Thereafter, SA node response was restored 6 months after surgery: Mean HR was 84 +/- 13/min at rest, 104 +/- 16/min at 60 W, and 130 +/- 20/min at peak exercise (P < .01 versus 1 month). PVO2 was also improved at this period (20.7 +/- 4.0 mL.min-1.kg-1, P < .01). The increase in PVO2 from 1 month to 6 months after surgery was correlated with the increase in peak HR (y = 0.73x +/- 3.6, r = .79). There were no further changes in heart rate response or PVO2 from 6 months to 1 year after surgery.
  
  
  CONCLUSIONS
  Atrial fibrillation was successfully treated by combined treatment with surgical repair for organic heart disease and the Maze procedure. However, SA node response to exercise was attenuated early after surgery. Thus, exercise capacity was improved at the late phase after surgery, which was related to the extent of restoration in SA node response.
authors.affiliation: Department of Medicine, National Cardiovascular Center, Osaka, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Tamai
authors.forename: Y
authors.initials: Y
authors.lastname: Kosakai
authors.forename: T
authors.initials: T
authors.lastname: Yoshioka
authors.forename: E
authors.initials: E
authors.lastname: Ohnishi
authors.forename: H
authors.initials: H
authors.lastname: Takaki
authors.forename: Y
authors.initials: Y
authors.lastname: Okano
authors.forename: Y
authors.initials: Y
authors.lastname: Kawashima
mesh_terms: D000328:Adult; D000368:Aged; D001281:Atrial Fibrillation / Q000503:physiopathology / Q000628:therapy*; D003131:Combined Modality Therapy; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012849:Sinoatrial Node / Q000503:physiopathology*; D016277:Ventricular Function, Left