 5. Atrial conduction time measured at the HRA after 30 seconds of constant pacing at a CL of 600, 500, and 400 ms. Conduction time is measured from the pacing artifact to the onset of the first initial sharp deflection recorded to the first A wave at CS1.10 and CS1.2. Total atrial conduction timePace HRA-Acs1.2; Right atrial conduction timePaceHRA-Acs9.10; Left atrial conduction timeAcs9.10-Acs1.2.6. Atrial electromechanical conduction time: three sampling points are taken at lateral mitral valveSa1, septal mitral valveSa2, lateral tricuspid valve Sa3, in the tissue doppler four-chamber view. Atrial electromechanical conduction time is measured from electrocardiogram P wave initiation to ultrasound A wave initiation. Total atrial electromechanical conduction timeT1-T3;Right atrial electromechanical conduction timeT2-T3; Light atrial electromechanical conduction timeT2-T1. 