Restoration of atrial function after the maze procedure for patients with atrial fibrillation. Assessment by Doppler echocardiography.

BACKGROUND: The purpose of the present study was to evaluate the effects of the maze procedure on atrial function in patients operated on for atrial fibrillation. The maze procedure is a new surgical intervention that is designed to restore sinus rhythm and active mechanical atrial contraction as a definitive treatment for patients with atrial fibrillation. METHODS AND
RESULTS: Doppler echocardiographic analysis of mitral and tricuspid inflow as well as pulmonary venous flow velocity was carried out in 46 patients 8 +/- 7 months after the maze procedure, and results were compared with those obtained from 27 age-matched control subjects. To evaluate atrial contraction, we determined the presence of atrial contribution to ventricular filling at the mitral and tricuspid valve levels and measured the percent atrial filling fractions of the left and right atria. To evaluate atrial compliance, we measured the systolic and the systolic-to-diastolic flow velocity ratios of the pulmonary venous inflow. Results were compared with similar measurements obtained from control subjects. Restoration of active atrial contraction was detected in 40 of the 46 patients (87%); right atrial contraction was noted in 38 patients (83%), and left atrial contraction was noted in 28 patients (61%). In patients with active atrial contraction, the percent atrial filling fraction of the right atrium was comparable to that of control subjects (32 +/- 7% versus 33 +/- 8%, P = NS), whereas that of the left atrium was smaller (20 +/- 5% versus 36 +/- 7%, P < .005). In addition, compared with control subjects, pulmonary venous flow in maze patients exhibited a reduced systolic component (17 +/- 4 versus 53 +/- 16 cm/s, P < .001) and decreased systolic-to-diastolic flow velocity ratio (0.3 +/- 0.01 versus 1.1 +/- 0.3, P < .001) and velocity integral ratio (0.3 +/- 0.01 versus 1.3 +/- 0.4, P < .001), all suggesting decreased left atrial filling.
CONCLUSIONS: The maze procedure restores active right atrial contraction and improves left atrial contraction in most patients. Obtained measurements suggest decreased left atrial compliance and reduced left atrial contribution to ventricular filling compared with control subjects. Despite the reduced indexes, qualitative restoration of function in either atria should translate in improved atrioventricular synchrony and reduction in thromboembolic events in patients with chronic or paroxysmal atrial fibrillation.