Echocardiographic assessment of Left Atrial Appendage function in patients with Mitral Stenosis by Tissue Doppler Velocity Imaging.

Introduction Rheumatic heart disease is one of the commonest cardiac conditions in India in both children and adults, accounting for 30 - 40% of cardiac cases admitted in hospital. Approximately 25% of all patients with rheumatic heart disease have pure or predominant mitral stenosis (MS). Thromboembolism develops in atleast 20% of mitral stenosis patients, at sometime during the course of their disease. Thromboembolism remains an important cause of morbidity and mortality in rheumatic MS. Echocardiography is the widely used method for detecting left atrial and left atrial appendage thrombi. Trans thoracic echocardiography (TTE) is only 50% sensitive in detecting LA and LAA thrombi.Transesophageal echocardiography (TEE) is 99% sensitive and specific in detecting LA and LAA thrombi. Echocardiography when combined with spectral and colour flow Doppler is well established as a safe, non-invasive, and versatile diagnostic modality in cardiology, and is now the predominant technique used for evaluation of left ventricular function and for the assessment and quantification of valvar heart lesions. When combined with physiological or pharmacological stress, echocardiography also enables the identification of reversible myocardial ischaemia and myocardial contractile reserve. However, assessment of regional cardiac dysfunction at rest and during stress remains subjective and semiquantitative, with high interobserver variability. Doppler measurement of myocardial motion,using pulsed wave Doppler, was first proposed in 1989 but this technique allowed realtime visualisation of only a single myocardial segment and its potential was not realised.Only later, with the development of colour flow algorithms to visualise myocardial motion,did the technique begin to gain clinical acceptability. TDI can be performed in pulsed-wave and color modes. Pulsed-wave TDI is used to measure peak myocardial velocities and is particularly well suited to the measurement of long-axis ventricular motion because the longitudinally oriented endocardial fibers are most parallel to the ultrasound beam in the apical views. Because the apex remains relatively stationary throughout the cardiac cycle, mitral annular motion is a good surrogate measure of overall longitudinal left ventricular (LV) contraction and relaxation. AIM OF THE STUDY: The most widely accepted method for assessing the left atrial appendage (LAA) function is the measurement of left atrial appendage late peak emptying velocity (LAAEV) by using pulse wave Doppler (PWD) on Transesophageal echocardiography (TEE) and reduced left atrial appendage late peak emptying velocity represents left atrial appendage dysfunction. The magnitude and pattern of left atrial appendage flow velocities are dependent on acute changes in loading conditions. Left atrial appendage flow velocities may also be affected by left atrial appendage size and morphology which are highly variable. Myocardial velocities obtained by Tissue Doppler imaging (TDI) are less dependent on preload and left atrial appendage (LAA) tissue velocities may help in more accurate risk prediction. CONCLUSION: Left Atrial Appendage function is depressed in patients with mitral stenosis as assessed by Left Atrial Appendage late peak Emptying Velocity and Left Atrial Appendage late peak Systolic velocity. The deterioration of Left Atrial Appendage function is more prominent among patients with Atrial fibrillation and those with embolic events. Left Atrial Appendage late peak Systolic velocity as assessed by Tissue Doppler imaging seems to be more reliable than Left Atrial Appendage late peak Emptying Velocity assessed with Pulse Doppler imaging in assessing Left Atrial Appendage function. Left Atrial Appendage late peak Systolic velocity is a useful parameter in evaluating Left Atrial Appendage function in patients with mitral stenosis