Background: In patients (pts) with sick sinus syndrome (SSS), right ventricular apical (RVA) pacing increased the risk of developing atrial fibrillation (AF). However, the mechanism of proarrhythmic effect of RVA pacing remains unclear. Methods: We performed detailed echocardiograhic examination with Tissue Doppler Imaging in 60 pts with SSS (mean age 73A9 years, 42 F) who implanted with DDD pacemakers during atrial and ventricular pacing with atrioventricular interval programmed at 120-150 mesc (ApVp mode) and AAI mode with (ApVs mode) at 70 bpm. Echo measurements were taken after 15 mins of pacing in each mode. The myocardial atrial contraction velocity was measured at annulus of right free wall (Ra), septal (Sa) and lateral free wall (La) respectively. Results: As expected, the AV interval was significantly shorter (118A25 vs.163A45 ms, P=0.002), and QRS duration was longer (146A33 vs.97A26 ms, P,0.001) during ApVp mode as compared with ApVs mode. Although there was no significant difference in left ventricular ejection fraction, left atrial (LA) ejection fraction (50A14 vs.55A14%, P=0.005), LA active emptying fraction (32A17 vs.37A16%, P=0.018) and LA filling fraction (43A13 vs. 48A13%, P=0.007) were all significant improved by 18%, 54% and 18%, respectively during ApVs mode as compared with ApVp mode. Furthermore, atrial myocardial contraction velocities among Ra (14.0A3.8 vs.15.2A4.6cm/s, P=0.026), Sa (7.8A2.6 vs. 8.8A2.8cm/s, P=0.001), and La (8.9A3.2 vs.9.7A2.7cm/s, P=0.020) were also significantly increased during ApVs mode by 12%, 19% and 21%, respectively as compared with ApVp mode (Figure). Conclusions: In pts with SSS, avoidance of RVA pacing during ApVs mode improves LA haemodynamic and mechanical function, which might contribute to a lower risk of development of AF after pacemaker implantation. P773Qualitative and quantitative assessment of 3 novel post-processing methods for enhancing echocardiographic images. Echocardiography, while a prevalent tool for assessing cardiac morphology and function, suffers from a range of artefacts that reduce its diagnostic value. This work qualitatively and quantitatively evaluates 3 novel post-processing methods for enhancing echocardiographic images. Data enhancement is achieved by utilising multiple partially decorrelated instances of a cardiac cycle acquired through a single acoustic window. Such information has until now been largely disregarded during data post-processing. Moreover, unlike past approaches, data enhancement is achieved without filtering out information based on static or adaptive selection criteria. Qualitative assessment using 32 clinical datasets demonstrated (i) suppression of cavity noise, (ii) increase in tissue/cavity contrast, and (iii) visual enhancement of tissue structures previously masked-out by various artefacts (Figure 1). The effect of each post-processing method on the diagnostic value of cardiac ultrasound data was quantitatively assessed by examining the repeatability coefficient variations (via Bland-Altman plots) in clini...
Funding Acknowledgements Type of funding sources: None. Introduction Evidence shows that atrial dysfunction and stunning occur, after successful cardioversion from persistent atrial fibrillation (AF) to sinus rhythm (SR). Electrical and mechanical recovery of the left atrium (LA), do not seem to coincide. Traditional Doppler parameters show reduced atrial contractility immediately after cardioversion, while mechanical improvement in atrial function mainly occurs within the first 4 weeks after sinus rhythm restoration. Purpose This study aimed to determine whether automated left atrial strain (auto-LA strain) could be used to measure global LA function and the time required for mechanical improvement to be seen in LA after cardioversion. Methods Auto-LA strain was measured via transthoracic echocardiography in 20 patients with persistent AF who had been cardioverted to SR and followed up for 3 months, and in a cohort of 20 healthy individuals. Conventional measures of atrial function derived from transmitral pulsed Doppler and tissue Doppler imaging of lateral mitral annulus were included, such as transmitral A wave velocity, A wave velocity-time integral, atrial fraction, A" wave velocity, and A" velocity-time integral. Results Immediately after cardioversion auto-LA strain was significantly lower than in control subjects. Atrial function improved over time with maximal change observed at 1 month after cardioversion. Doppler tissue imaging parameters were also normalised after 1 month of restoration to SR. Despite this initial improvement in LA function, the values of auto-LA strain remained stable for the following 3 months. Conclusion Although the electrical function of LA is immediately restored after successful cardioversion in AF patients, there remains a persistent degree of atrial dysfunction for at least 3 months. This difference could explain the increased propensity for these patients to develop recurrent atrial fibrillation. Additionally, this dysfunction could indicate longer-term use of anti-arrhythmic and antithrombotic medications in the AF cohort. Abstract Figure.
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