13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

RT-245

Left atrial appendage wall velocities and cycle length of atrial fibrillation waves detected by tissue Doppler imaging in normal and chronic atrial fibrillation patients

Paolo Trambaiolo, Gerardo Ansalone*, Luca Cacciotti, Donato Di Donato, Francesco Fedele.
I Cardiology, Cardiovascular and Respiratory Sciences Department, University "La Sapienza", Rome, *S. Filippo Neri Hospital, Rome, Italy

Background

The color-coded Doppler flow imaging technique, started in 1983 and widely developed for two-dimensional echocardiographic visualization of intracardiac and intravascular physiological and pathological flows, has been recently used for measuring the velocity of myocardial wall^1,2. Tissue Doppler imaging (TDI) is a software modification of a standard color Doppler technique: the signals generated by the myocardial wall of low velocity (< 15 cm/sec) and of high amplitude, rather than those produced by intracavitary flow of high velocity (15-120 cm/sec) and low amplitude are analyzed, using the auto-correlation and velocity calculation method. Thus it is possible to visualize the wall motion in a color-coded mode^3-6: the red color signifies that the cardiac tissue move towards the transducer, while the blue color means that it moves away from the transducer. The maximum color brightness corresponds to the upper limit of the measurable velocity range, which is to the maximum value of the frequency Doppler shift. The different brightness of blue or red colors is proportional to the velocity and to the direction of the myocardial tissue. Two other important characteristics of this system must be remembered: the availability of a high frame rate (50-60/sec), that is particularly useful image post-processing and the high spatial resolution (typically 2x2 mm).

TDI technique allows another modality to measure the myocardial wall velocities (pulsed wave tissue Doppler imaging or PW-TDI) by positioning the sample volume on the myo-cardial wall: the curves of the regional myocardial velocity
distribution can be obtained during the whole cardiac cycle⁷.

As it is well known, the omniplane transesophageal echocardiographic examination (TEE) correctly identifies several morphologic aspects of left atrial appendage (LAA)^8-14, but till today the LAA function pattern has been indirectly obtained by emptying flow velocities and % area change alone.