Transthoracic tissue Doppler assessment of left atrial appendage contraction and relaxation: their changes with aging

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.

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.

Relevance of transthoracic left atrial appendage wall velocity measurement in addition to left atrial volume for noninvasive and quantitative assessment of left atrial thrombogenesis in patients with atrial fibrillation and normal D-dimer levels

PURPOSE

This study examined the role of left atrial (LA) appendage wall velocity (LAAWV) measurement in addition to LA size for the noninvasive assessment of thrombogenesis in patients with atrial fibrillation (AF) and normal plasma D-dimer levels.

METHODS

In 58 non-valvular AF patients, LAAWV and the LA volume index (LAVI) were determined by transthoracic echocardiography. LA appendage flow velocity and severity of spontaneous echo contrast (SEC) were determined by transesophageal echocardiography.

RESULTS

LAAWV was strongly correlated with LA appendage flow velocity (r = 0.82), and LAVI was weakly correlated with LA appendage flow velocity (r = -0.37). As SEC severity increased, LAAWV decreased (p < 0.001) and LAVI increased (p < 0.001). Among 52 patients with normal D-dimer levels, LAAWV < 10 cm/s had 71 % sensitivity and 94 % specificity for diagnosing severe SEC. Severe SEC was not found in 18/32 large LAVI patients (>34 mL/m(2)), but 17 of the 18 patients (94 %) had LAAWV < 10 cm/s. Severe SEC was found in 3/20 patients with normal LAVI, but all of them showed LAAWV < 10 cm/s.

CONCLUSION

The noninvasive measurement of transthoracic LAAWV in addition to LA volume is clinically relevant for quantitatively assessing thrombogenesis in AF patients with normal D-dimer levels.

Assessment of normal left atrial appendage anatomy and function over gender and ages by dynamic cardiac CT

OBJECTIVES

The aim of this study was to evaluate variations in anatomy and function according to age and gender using cardiac computed tomography (CT) in a large prospective cohort of healthy patients.

BACKGROUND

The left atrial appendage (LAA) is considered the most frequent site of intracardiac thrombus formation. However, variations in normal in vivo anatomy and function according to age and gender remain largely unknown.

METHODS

Three-dimensional (3D) cardiac reconstructions of the LAA were performed from CT scans of 193 consecutive patients. Parameters measured included LAA number of lobes, anatomical position of the LAA tip, angulation measured between the proximal and distal portions, minimum (iVolmin) and maximum (iVolmax) volumes indexed to body surface area (BSA), and ejection fraction (LAAEF). Relationship with age was assessed for each parameter.

RESULTS

We found that men had longer and wider LAAs. The iVolmin and iVolmax increased by 0.23 and 0.19 ml per decade, respectively, while LAAEF decreased by 2% per decade in both sexes.

CONCLUSIONS

Although LAA volumes increase, LAAEF decreases with age in both sexes.

KEY POINTS

• Variations in normal left atrial appendage in vivo anatomy and function remain largely unknown. • Cardiac CT is reliable for left atrial appendage volume measurements. • Although LAA volumes increase, LAAEF decreases with age in both sexes.

Left atrial appendage exclusion for atrial fibrillation

Percutaneous left atrial appendage (LAA) closure is being increasingly used as a treatment strategy to prevent stroke in patients with atrial fibrillation (AF) who have contraindications to anticoagulants. Several approaches and devices have been developed in the last few years, each with their own unique set of advantages and disadvantages. In this article, the published studies on surgical and percutaneous approaches to LAA closure are reviewed, focusing on stroke mechanisms in AF, LAA structure and function relevant to stroke prevention, practical differences in procedural approach, and clinical considerations surrounding management.

Left atrial appendage wall-motion velocity associates with recurrence of nonparoxysmal atrial fibrillation after catheter ablation

Catheter ablation (CA) for nonparoxysmal atrial fibrillation (AF) is controversial due to its high recurrence rate. The aim of this study was to assess retrospectively the diagnostic value of preprocedural left atrial appendage (LAA) wall-motion velocity in predicting recurrence of AF within 1 year after CA. We hypothesized that tissue Doppler-derived measurement of LAA wall-motion velocity associate with recurrence of AF within 1 year after CA. We retrospectively reviewed 47 consecutive patients with nonparoxysmal AF (defined as AF lasting for 1 week or longer) who underwent both transthoracic and transesophageal echocardiography before their first treatment by CA in a single center. Forty-one patients aged 58 ± 10 years were included, and variables predicting the recurrence of AF within 1 year after CA were evaluated. Seventeen patients (41%) developed recurrence of AF within 1 year after CA. Univariate analyses showed that preprocedural LAA upward wall-motion velocity at the apex assessed by transesophageal echocardiography was significantly lower in patients with recurrence of AF than those without recurrence (OR = 1.45, 95% CI: 1.13-2.01, P = 0.009). Multivariate logistic analyses including other potential predictors (duration of AF, left ventricular ejection fraction, E-wave deceleration time, and left atrial wall-motion velocity) identified LAA upward wall-motion velocity at the apex as an independent predictor of outcome. These data suggest in patients with nonparoxysmal AF, preprocedural LAA upward wall-motion velocity at the apex, as determined by tissue Doppler imaging during transesophageal echocardiography, may be a useful indicator for predicting recurrence of AF within 1 year after CA.

High plasma human atrial natriuretic peptide and reduced transthoracic left atrial appendage wall-motion velocity are noninvasive surrogate markers for assessing thrombogenesis in patients with paroxysmal atrial fibrillation

BACKGROUND

The clinical relevance of examining human atrial natriuretic peptide (HANP) or left atrial appendage (LAA) wall-motion velocity during sinus rhythm in paroxysmal atrial fibrillation (AF) patients has not been clearly elucidated.

METHODS

The subjects were 38 patients with paroxysmal AF who underwent transesophageal and transthoracic echocardiography during sinus rhythm. The presence of spontaneous echocontrast (SEC) was examined with transesophageal echocardiography and LAA wall-motion velocity (LAAWV) was measured with transthoracic tissue Doppler echocardiography. Plasma HANP was measured within 3 hours after echocardiography.

RESULTS

Human atrial natriuretic peptide ranged from 12 to 106 pg/mL with an average of 43 ± 24 pg/mL and had a significant correlation with LAAWV (r = -0.57) or LAA flow velocity (r = -0.41). HANP was significantly higher in patients with SEC than in patients without SEC (64 ± 29 vs. 34 ± 15 pg/mL, P = 0.008) and LAAWV was significantly lower in patients with SEC than in patients without SEC (13 ± 5 vs. 20 ± 5 cm/sec, P = 0.002). HANP >44 pg/mL had a sensitivity of 73% and specificity of 89% for diagnosing SEC. SEC was more frequently observed (73%) in patients with HANP >44 pg/mL and/or LAAWV <10 cm/sec as compared with patients (11%) with normal HANP and LAA wall-motion velocity (P < 0.0001).

CONCLUSION

Higher plasma HANP and lower LAA wall-motion velocity may be noninvasive surrogate markers for assessing left atrial thrombogenesis during sinus rhythm in paroxysmal AF patients.