Atrial Na,K-ATPase increase and potassium dysregulation accentuate the risk of postoperative atrial fibrillation.
BACKGROUND
Postoperative atrial fibrillation is a common complication to cardiac surgery. Na,K-ATPase is of major importance for the resting membrane potential and action potential. The purpose of the present study was to evaluate the importance of Na,K-ATPase concentrations in human atrial biopsies and plasma potassium concentrations for the development of atrial fibrillation.


METHODS
Atrial myocardial biopsies were obtained from 67 patients undergoing open chest cardiac surgery. Na,K-ATPase was quantified using vanadate-facilitated 3H-ouabain binding. Plasma potassium concentration was measured with ion-selective electrode.


RESULTS
In patients with preoperative sinus rhythm, 3H-ouabain-binding site concentration was 16% higher in patients developing postoperative atrial fibrillation compared to patients maintaining sinus rhythm [302 +/- 15 pmol/g wet weight (n = 20) vs. 261 +/- 11 mmol/g wet weight (n = 33), p = 0.03]. Also with multivariable analysis, 3H-ouabain-binding site concentration was significantly associated with the development of atrial fibrillation. High increase in plasma potassium concentration during the perioperative period and surgery was associated with postoperative atrial fibrillation.


CONCLUSIONS
The present study supports the increasing evidence of dysregulation of the potassium homeostasis as an important factor in the development of cardiac arrhythmias. High atrial Na,K-ATPase and sudden plasma potassium concentration increase may contribute to precipitate atrial fibrillation.
Tran
Cao Thach
CT
Laboratory for Molecular Cardiology, Medical Department B, The Heart Centre, Rigshospitalet, Juliane Maries Vej 20, Copenhagen DK-2100, Denmark. tran@dadlnet.dk
Schmidt
Thomas Andersen
TA
Christensen
John Brochorst
JB
Kjeldsen
Keld
K
D000368:Aged; D001281:Atrial Fibrillation / Q000201:enzymology* / Q000209:etiology / Q000503:physiopathology; D003718:Denmark; D005260:Female; D006325:Heart Atria / Q000201:enzymology*; D006706:Homeostasis; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology; D010042:Ouabain; D011183:Postoperative Complications / Q000097:blood / Q000201:enzymology / Q000503:physiopathology; D011188:Potassium / Q000097:blood*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013903:Thoracic Surgery
D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium