الفهرس 
َِAcknowledegementOnly 14 pages are availabe for public view
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Abstract
AF is a progressive condition that begins with hemodynamic and/or structural changes in the left atrium (LA) and evolves through the paroxysmal and persistent stage.
The aim of this thesis was:(1) to determine the contribution of LA mechanical function, including LA stiffness, to AF progression by comparing patients with paroxysmal and persistent AF with normal control subjects, and to evaluate whether LA mechanical function and stiffness are related with the structural changes of LA, (2) Estimation of left ventricular filling pressure depending on tissue Doppler utility and evaluation of its relation to atrial stiffness.
Speckle tracking echocardiography allows the quan¬tification of LA function, and recently, noninvasive estimate of LA strain by speckle tracking has been proposed.
Estimation of LV filling pressures using E/e may be of clinical utility for management of patients in whom a definite indication to rate or rhythm control strategy does not exist.
Our hypothesis was that E/e is a more accurate predictor of hemodynamic load and thus could predict even precocious AF relapse.
twenty paroxysmal AF patients (51 ± 13 years, 60% male), 20 persistent AF patients (49 ± 8 years, 65% male), were studied, using a speckle tracking and tissue doppler echocardiography, and were compared with 20 age-, gender-, and left ventricular (LV) EF matched controls (46 ± 8 years, 60% male). LA maximal volume, mitral annular velocities, and global longitudinal LA strain were measured. The ratio of E/e’ to LA strain was used as an index of LA stiffness.
Patients with paroxysmal and persistent AF had similar age, gender, heart rate and LV ejection fraction, when compared with that of the normal controls. However, paroxysmal and persistent AF patients showed increased LA maximal volume (24.3±3.2, 20.1±5.2 vs. 18.3±1.6, p <0.001) and LV filling pressure (9.5±1.1, 7.9±1.2 vs. 6.8±1.1, p <0.001), but decreased mitral annular velocities and LA strain (18.1±2.8, 21.5±4.3 vs. 25.9±2.9, p <0.001). LA stiffness was increased in patients with persistent and paroxysmal AF than in the control subjects (0.55±0.12, 0.36 ± 0.09 vs. 0.26 ± 0.02, p <0.001), and was related with LA diameter and LV filling pressure.
So there was a correlation between LA stiffness and LV filling pressure and AF progress.
The important role of LV diastolic dysfunction in promoting and perpetuating AF is well established.
The link between diastolic impairment and risk of AF is mediated by long-term left atrial pressure overload, which favors progressive left atrial enlargement and electrical instability.
Furthermore, Better understanding of LA structure and function could lead to improvements in our ability to predict the risk of developing AF and the response to treatment in patients with this arrhythmia