Left Atrial Appendage Function Analyzed by Tissue Doppler Imaging in Mitral Stenosis: Effect of Afterload Reduction after Mitral Valve Commissurotomy

Assessment of left atrial appendage function by echocardiography

The left atrial appendage (LAA) is considered not only to be the most frequent site of thrombus formation, but also to play a pivotal role in maintaining normal cardiac function. Transesophageal echocardiography (TEE) is widely used to assess LAA function. The LAA flow velocity has been used as a surrogate for LAA function, and it varies with multiple interrelated factors including age, hemodynamics, type of arrhythmia, and antiarrhythmic interventions. Relatively great importance of LAA function is involved with intraatrial thrombus formation and subsequent thromboembolism, and thus, understanding of characteristics and behaviors of the LAA under various clinical conditions may help determine strategies against atrial thrombosis. Also, techniques other than TEE-derived Doppler to assess LAA function, such as tissue Doppler imaging, have been proposed. In this review, we introduce clinical and echocardiographic correlates of LAA function, the LAA flow velocity in particular, its significance, and how to interpret functional patterns of the LAA each relevant to specific clinical settings.

Evaluating left atrial appendage function in a subtype of non-valvular atrial fibrillation using transesophageal echocardiography combined with two-dimensional speckle tracking

BACKGROUND

The use of transesophageal echocardiography (TEE) is a clinically feasible method for quantitative analysis of left atrial appendage (LAA) function. LAA dysfunction is closely associated with atrial fibrillation (AF)-related stroke. However, there are few studies on the changes in LAA function in patients with different types of AF. This study aimed to observe changes in LAA systolic motion and function in patients with different types of AF by using speckle-tracking echocardiography (STE).

METHODS

A retrospective study of 216 patients with non-valvular AF was conducted. The LAA was divided into three parts: the basal segment (B), middle segment (M), and top segment (A). Speck -racking technology was used to measure and record the forward strain values of the basal segment (B), middle segment (M), and top segment (A) of the LAA, and the peak positive strain dispersion of the LAA was calculated. The left atrial appendage mechanical dispersion (LAAMD) was defined as the standard deviation (SD) of the peak positive strain at each segment of the R-R interval.

RESULTS

Partial speckle-tracking parameters of the LAA showed statistical significance between the two groups. The peak strain on the top segment of the LAA was reduced in the persistent atrial fibrillation (per-AF) group compared to the paroxysmal atrial fibrillation (par-AF) group [11.87 (6.47-20.12) vs. 16.02 (9.76-24.50); 12.66 (6.66-21.22) vs. 20.16 (14.16-30.56); both P<0.01]. In the group with lower LAAMD, the proportion of patients with persistent AF (per-AF) was higher (66.3% vs. 33.7%; P<0.001), the left atrial dilatation was more significant (45.80±5.656 vs. 42.85±4.867; P<0.001), the LAA filling velocity and LAA empty velocity were lower (42.35±20.354 vs. 51.0±20.599; 38.71±24.39 vs. 51.62±21.282; both P<0.001), the LAA ejection fraction was significantly lower (52.16±25.538 vs. 70.85±20.741; P=0.000), and the peak positive strains of the M and A of the LAA were lower than those in the higher LAAMD group.

CONCLUSIONS

The deformability of the LAA is decreased diffusely in per-AF, especially in the A of the LAA. Compliance with LAA was worse in patients with per-AF than in those with par-AF.

Study of immediate and late effects of successful PTMC on left atrial appendage function in patients with severe rheumatic mitral stenosis IN SINUS rhythm

INTRODUCTION

Since its introduction in 1984, Percutaneous Transvenous Mitral Commissurotomy (PTMC) has become established as a safe and effective treatment for rheumatic Mitral Stenosis (MS).( Ben Farhat et al., 1998) 1 Chronic pressure and volume overload imposed by MS causes left atrial (LA) and Left Atrial Appendage (LAA) dysfunction. Risk of cerebrovascular accident (CVA) is increased approximately 17-fold in patients of MS in Atrial Fibrillation (AF) and is present even in patients of MS in sinus rhythm (SR). This study was undertaken to evaluate the effect of PTMC on LAA function by Trans-esophageal echocardiography (TEE) Doppler and Doppler Tissue Imaging (DTI).

METHODS

Total 70 cases were enrolled in this study. Patients with symptomatic severe MS (Mitral Valve Area <1.5cm2), in SR, who underwent a successful PTMC during the period from May 2016 to May 2019 were selected. All the patients underwent Clinical examination, ECG, detailed TTE and TEE before, immediately after (within 24 h) & after 6 months of PTMC.

RESULTS

There was non significant improvement in Left Atrial appendage fractional area change {LAAAC (%)} immediately Post PTMC but there was significant improvement at 6 months Post PTMC. There was significant increase in LAA PW Doppler velocities (LAAEDE, LAALDE and LAAF velocity) immediately Post PTMC which got further improved significantly at 6 months of follow up. There was significant increase in LAA DTI velocities (E_LAA, A_LAA and S_LAA velocity) immediately Post PTMC which got further improved significantly at 6 months of follow up.

CONCLUSION

PTMC improves left atrial appendage function in patients with mitral stenosis.

Left atrial mechanical remodelling assessed as the velocity of left atrium appendage wall motion during atrial fibrillation is associated with maintenance of sinus rhythm after electrical cardioversion in patients with persistent atrial fibrillation

The velocity of left atrium appendage (LAA) wall motion during atrial fibrillation (AF) is a potential marker of mechanical remodelling. In this study, we investigated whether the velocity of LAA wall motion during AF predicted the success of electrical cardioversion and long-term sinus rhythm maintenance. Standard echocardiographic data were obtained by transthoracic echocardiography, and LAA wall motion velocities were measured by transoesophageal echocardiography. With logistic regression and receiver operating characteristic curve analyses, we related echocardiographic and clinical data to cardioversion outcomes and sinus rhythm maintenance at 12 months. Of 121 patients prospectively included in the study, electrical cardioversion restored sinus rhythm in 97 (81.2%), and 51 (42%) patients maintained sinus rhythm at 12 months. Patients in whom cardioversion restored sinus rhythm had higher LAA wall motion velocities than did the patients with failed cardioversions (p <0.001). Compared to patients with AF at 12 months, patients who maintained sinus rhythm had lower maximum and end-diastolic left atrial volumes (p ≤ 0.01), lower E/e’ ratios (p = 0.005), higher s’ values (p = 0.013), and higher LAA motion velocities (p < 0.001). On multivariate logistic regression, only LAA wall motion velocity and E/e’ ratios remained significant predictors of sinus rhythm maintenance at 12 months (p ≤ 0.04). LAA wall motion velocity was also a significant predictor of sinus rhythm maintenance when corrected for clinical variables (p = 0.039). Conclusion: LAA wall motion velocity, as a marker of mechanical remodelling, can predict short-term and long-term sinus rhythm maintenance after electrical cardioversion in AF.

Assessment of left atrial appendage function during sinus rhythm in patients with obstructive sleep apnea

Objective:

Obstructive sleep apnea (OSA) is associated with thromboembolic events. Compromised left atrial appendage (LAA) function due to left ventricular (LV) performance abnormality, often present in patients with OSA, may play an important role. The purpose of this study is to evaluate LV and LAA mechanical functions during sinus rhythm (SR) in patients with OSA.

Methods:

LV and LAA functions were assessed in 43 OSA patients and compared with that of 20 control patients in SR. Tissue Doppler velocities of the LAA apex and emptying velocities (EV) of LAA were obtained on parasternal short-axis view.

Results:

The baseline clinical characteristics were similar except for AHI (apnea-hypopnea index), minimal SaO₂, mean SaO₂, hypertension, and body-surface area. Most of the LV echocardiographic parameters significantly deteriorated in OSA patients in comparison with those in the control group. LAA EV, LAA systolic relaxation velocity (S_M), LAA early-diastolic velocity (E_M), LAA contraction velocity (A_M), left atrial (LA) minimum volume index, LA ejection fraction, LA conduit volume index, and LA reservoir volume index were lower in OSA patients compared with those in the control group (p<0.05). LAA A_M was negatively correlated with AHI and the ratio of peak early diastolic flow velocity (E) to early-diastolic (E’) and positively correlated with LA conduit volume (p<0.05). Multiple predictors for LAA A_M were AHI, presence of diastolic dysfunction, and E/E’ values (p<0.05).

Conclusion:

LAA mechanical function is significantly depressed in patients with OSA and SR. LAA dysfunction may predispose these patients to thromboembolic events. The evaluation of LAA mechanical function by tissue Doppler study using transthoracic echocardiography (TTE) may become an alternative for routine work-up in OSA patients.

Effect of percutaneous mitral balloon valvuloplasty on left atrial appendage function: transesophageal echo study

BACKGROUND

To compare left atrial appendage (LAA) function by Doppler and Doppler tissue imaging (DTI) before and after percutaneous balloon mitral valvuloplasty (PBMV).

MATERIALS AND METHODS

Fifty-nine patients with symptomatic rheumatic mitral stenosis who underwent PBMV were included in this study. LAA function was measured before and after PBMV. To study LAA function, LAA late emptying (LAALE) velocity, LAA late filling (LAALF) velocity, and LAA area change percentage (LAAAC %) were measured. In the DTI study, tissue Doppler velocities of the LAA, including peak early diastolic (E(LAA)), peak late diastolic (A(LAA)), and peak systolic (S(LAA)), were measured.

RESULTS

There was significant increase in LAALE velocity, LAALF velocity, E(LAA), A(LAA), S(LAA) waves measured by Doppler and DTI after PBMV compared with baseline (p < 0.001) but there was no significant change in LAAAC% (p = not significant). Spontaneous echo contrast was present in 10 of the 59 patients before the procedure. It completely disappeared (6 patients) or decreased (4 patients) after PBMV.

CONCLUSIONS

Our results suggest that PBMV improves LAA function and, thereby, may have a favorable influence on future thromboembolic complications.

Effect of percutaneous transvenous mitral commissurotomy on left atrial appendage function: an immediate and 6-month follow-up transesophageal Doppler study

BACKGROUND

The left atrial appendage (LAA) is a common site of thrombus formation and is the source of systemic thromboembolism in patients with rheumatic mitral stenosis. LAA contractile dysfunction is a common finding in these patients. The aim of this study was to assess immediate and 6-month follow-up LAA function by transesophageal Doppler echocardiography in patients who underwent percutaneous transvenous mitral commissurotomy (PTMC).

METHODS

Forty-seven consecutive patients with symptomatic critical mitral stenosis who underwent PTMC were enrolled. All had underwent transthoracic and transesophageal echocardiography before, 24 hours after, and 6 months after PTMC. Pulse Doppler velocities of the LAA were measured, including peak early diastolic (E wave), peak late diastolic (A wave), and peak systolic (S wave). The corresponding tissue Doppler velocities of the LAA, including peak early diastolic (E(LAA)), peak late diastolic (A(LAA)), and peak systolic (S(LAA)), were also measured. LAA ejection fraction was measured using the modified Simpson's method.

RESULTS

The mean age of the 47 enrolled patients was 31.7 ± 10.26 years. Thirty-eight patients were in sinus rhythm, and the remaining nine were in atrial fibrillation. PTMC was successful in all patients. The pulse Doppler velocities of the LAA at baseline, after PTMC, and at 6-month follow-up were as follows: for the E wave, 15.29 ± 2.26, 17.02 ± 2.25, and 17.97 ± 2.55 cm/sec, respectively (P < .001); for the A wave 22.45 ± 4.11, 24.19 ± 4.21, and 25.99 ± 4.51 cm/sec, respectively (P < .001); and for the S wave, 28.52 ± 4.37, 31.45 ± 5.37, and 33.06 ± 4.99 cm/sec, respectively (P < .001). The corresponding tissue Doppler velocities of LAA were as follows: for E(LAA), 4.65 ± 0.91, 5.28 ± 0.85, and 5.80 ± 0.84 cm/sec, respectively (P < .001); for A(LAA), 6.67 ± 1.12, 7.33 ± 1.17, and 7.88 ± 1.22 cm/sec, respectively (P < .001); and for S(LAA), 4.67 ± 1.12, 5.52 ± 1.18, 6.07 ± 1.11 cm/sec, respectively (P < .001). There was a nonsignificant increase in LAA ejection fraction (48.97 ± 8.14% vs 52.3 ± 13.76% vs 52.11 ± 16.3%, respectively, P = .052). On subgroup analysis between patients in sinus rhythm and those with atrial fibrillation, there was no significant difference for LAA ejection fraction and pulse and tissue Doppler velocities. Very good intraclass correlation of the LAA parameters was also observed for the reproducibility of the data.

CONCLUSIONS

The present study shows contractile dysfunction of the LAA in patients with critical mitral stenosis, which significantly improved after PTMC, and a further improvement was observed at 6-month follow-up. Favorable 6-month improvements in LAA parameters suggest continuous structural remodeling of the LAA after PTMC, which is clinically attributed to the absence of thromboembolism. Although there was an improvement in LAA function, it was far below the normal range, suggesting a need for continuous long-term monitoring and management of thromboembolism in these patients.

Approaching regional left atrial function by tissue Doppler velocity and strain imaging

Atrial function is an integral part for the proper performance of the circulatory system. Assessment of its haemodynamic and mechanical characteristics by use of non-invasive echocardiography, including tissue Doppler velocity and strain imaging, may provide a better insight into atrial function and its relationship with ventricular function. From an electromechanical perspective, this review summarizes not only the various methods for evaluating regional atrial function by tissue Doppler imaging, but also the normal findings in healthy subjects and the major clinical utilities in cardiac diseases, such as atrial fibrillation, ischaemic heart disease and heart failure.

Systolic Tissue Velocity Is a Useful Echocardiographic Parameter in Assessment of Left Atrial Appendage Function in Patients with Mitral Stenosis

BACKGROUND

The incidence of thromboembolism remains high in patients with mitral stenosis (MS). The left atrial appendage (LAA) is a potential site for development of thrombus and LAA dysfunction is an independent predictor of thromboembolism. The LAA dysfunction is represented by reduced LAA late emptying velocity. But the magnitude of LAA flow velocities is dependent on acute changes in loading conditions.

AIM

To investigate the value of the LAA tissue velocities obtained by tissue Doppler imaging (TDI) in assessment of LAA function in MS patients with and without thromboembolic events.

METHODS

The study population consisted of 98 isolated MS patients of 32 age and sex-matched healthy controls. All subjects underwent transesophageal echocardiography (TEE). LAA late peak emptying (LAAEV) and filling (LAAFV) flow velocities were recorded. LAA peak late tissue systolic (LSV) and diastolic (LDV) tissue velocities by TDI were measured. The patients were divided into three groups as Group I (n = 38, sinus rhythm and LAAEV > or = 25 cm/s), Group II (n = 26, sinus rhythm and LAAEV < 25 cm/s), and Group III (n = 34, atrial fibrillation).

RESULTS

Twenty-one patients had thromboembolic events. LAAEV, LAAFV, LSV, and LDV were significantly reduced in patients with embolic events. Spontaneous echo contrast (SEC) density was strongly negative correlated with LSV, whereas weakly negative correlated with LAAEV. Multivariate regression analysis showed that LSV and the presence of SEC were independently associated with embolic events.

CONCLUSION

LSV seems more reliable and useful parameter in evaluating LAA function. LAA function is more depressed among patients with embolic events.

Left atrial stiffness and its implications for cardiac function

Proper atrial function is essential for overall cardiovascular performance, mainly by its four major functions, namely, bioelectrical, hormonal, metabolic and hemodynamic. With regard to the latter, atria modulate ventricular filling by smoothing the transformation of the continuous venous return to the intermittent filling pattern of the ventricles during diastole through three main components: a phase of reservoir mainly during ventricular systole, a conduit phase during ventricular diastole and an active phase in late ventricular diastole. Although the atria assume a dynamic role in ventricular filling progression, atrial function and emptying pattern is, conversely, highly influenced by the ventricular diastolic wall stress, underlying the close connection observed between these chambers. This review focuses essentially on left atrial mechanical role, particularly on the physiological and clinical consequences of disturbed atrial compliance.