Tissue Doppler derived atrial conduction time: PA-TDI

Tissue Doppler derived atrial conduction time: PA-TDI

Total atrial conduction time (TACT) denotes the total period required for atrial activation. Conventionally it is measured using signal averaged electrocardiogram (SA-ECG) as the maximal P wave duration. It has been shown to be powerful predictor of atrial fibrillation. A simpler method which can be done in any echocardiography laboratory without the use of SA-ECG is a tissue Doppler and surface ECG combined measurement of atrial activation. PA-TDI is measured from the onset of the P wave on surface ECG to the tissue Doppler derived peak of A wave at the lateral left atrial wall). PA-TDI has been shown to predict new onset atrial fibrillation (AF), recurrence of AF after ablation, AF after acute myocardial infarction and even AF after cardiac surgery [1]. Cardiac surgeries in which PA-TDI has been successfully used to predict AF include coronary artery bypass grafting (CABG), aortic valve replacement (AVR) for aortic stenosis [2] and surgery for mitral regurgitation [3].

In mitral regurgitation, prediction of AF is very important as the left atrium is very large. Onset of AF after relief of mitral regurgitation jet which has a cleansing action on the left atrium may lead to thrombus formation and increase the risk of stroke and other systemic embolism [1].

References

1. Yuasa T, Imoto Y. Usefulness of Tissue Doppler Imaging-Derived Atrial Conduction Time for Prediction of Atrial Fibrillation. Circ J. 2016;80(1):58-9.
2. Takahashi S, Fujiwara M, Watadani K, Taguchi T, Katayama K, Takasaki T, Kurosaki T, Imai K, Sueda T. Preoperative tissue Doppler imaging-derived atrial conduction time can predict postoperative atrial fibrillation in patients undergoing aortic valve replacement for aortic valve stenosis. Circ J. 2014;78(9):2173-81. 
3. Takahashi S, Katayama K, Watanabe M, Kodama H, Taguchi T, Kurosaki T, Imai K, Sueda T. Preoperative tissue Doppler imaging-derived atrial conduction time predicts postoperative atrial fibrillation in patients undergoing mitral valve surgery for mitral valve regurgitation. Circ J 2016; 80: 101–109.