Assessment of atrial regional and global electromechanical function by tissue velocity echocardiography: a feasibility study on healthy individuals

Study the relationship between left atrial (LA) volume and left ventricular (LV) diastolic dysfunction and LV hypertrophy: Correlate LA volume with cardiovascular risk factors

Heart failure (HF) with normal ejection fraction - the isolated diastolic heart failure, depicts increasing prevalence and health care burden in recent times. Having less mortality rate compared to systolic heart failure but high morbidity, it is evolving as a major cardiac concern. With increasing clinical use of Left atrial volume (LAV) quantitation in clinical settings, LAV has emerged as an important independent predictor of cardiovascular outcome in HF with normal ejection fraction. This article is intended to review the diastolic and systolic heart failure, their association with left atrial volume, in depth study of Left atrial function dynamics with determinants of various functional and structural changes.

Left Atrial Velocity Vector Imaging Can Assess Early Diastolic Dysfunction in Left Ventricular Hypertrophy and Hypertrophic Cardiomyopathy

BACKGROUND

The function of left atrium (LA) is difficult to assess because of its ventricle-dependent, dynamic movement. The aim of this study was to assess LA function using velocity vector imaging (VVI) and compare LA function in patients with hypertrophic cardiomyopathy (HCMP) and left ventricular hypertrophy (LVH) with normal controls.

METHODS

Fourteen patients with HCMP (72% male, mean age of 52.6 ± 9.8), 15 hypertensive patients with LVH (88% male, mean age of 54.0 ± 15.3), and 10 age-matched controls (83% male, mean age of 50.0 ± 4.6) were prospectively studied. Echocardiographic images of the LA were analyzed with VVI, and strain rate (SR) was compared among the 3 groups.

RESULTS

The e' velocity (7.7 ± 1.1; 5.1 ± 0.8; 4.5 ± 1.3 cm/sec, p = 0.013), E/e' (6.8 ± 1.6; 12.4 ± 3.3; 14.7 ± 4.2, p = 0.035), and late diastolic SR at mid LA (-1.65 ± 0.51; -0.97 ± 0.55; -0.82 ± 0.32, p = 0.002) were significantly different among the groups (normal; LVH; HCMP, respectively). The e' velocity, E/e', and late diastolic SR at mid LA were significantly different between normal and LVH (p = 0.001; 0.022; 0.018), whereas LA size was similar between normal and LVH (p = 0.592). The mean late diastolic peak SR of mid LA was significantly correlated with indices of diastolic function (E/e', e', and LA size).

CONCLUSIONS

The SR is a useful tool for detailed evaluation of LA function, especially early dysfunction of LA in groups with normal LA size.

Atrial cardiomyopathy: Diagnosis, clinical implications and unresolved issues in anticoagulation therapy

Atrial cardiomyopathy (AC) is an evolving pathophysiological entity that has expanded our understanding regarding the atrium and its role in arrhythmogenesis and cardiac thromboembolism. The pathological myocardium in AC promotes arrhythmogenesis through mechanical dysfunction (hypocontractility, fibrosis), adverse alterations of the endothelium and secretion of prothrombotic factors (IL-6, IL-8, TNF-a). 'Red flags', indicative of AC, can be recognized either non-invasively by electrocardiography, echocardiography and cardiac magnetic resonance imaging or invasively by high-density electroanatomical mapping as low bipolar voltage areas of the affected myocardium. Signs of AC have been strongly associated with an increased risk of ischemic stroke, even embolic strokes of undetermined source, regardless of the coexistence of atrial fibrillation (AF). The underlying existence of AC has been negatively correlated with the success rate of catheter ablation of AF. The clinical value of AC is the provision of a novel pathway regarding the potential mechanisms of cerebrovascular events of cardiac thromboembolic origin. In addition, AC may serve as a risk stratification tool to predict the long-term responders of AF catheter ablation.

Bachmann bundle impairment following linear ablation of left anterior wall: impact on left atrial function

We aimed to evaluate the effect of Bachmann bundle (BB) impairment on electrical and mechanical function of the left atrium (LA), as well as the long-term clinical impact of such impairment. We measured activation time in the five LA walls in 56 patients with atrial fibrillation. LA reservoir, conduit, and contractile function were also evaluated. Patients were divided into two groups based on ablation strategy: the circumferential pulmonary vein isolation (CPVI) group and CPVI with LA anterior wall linear ablation (LAAW) group. Patients in the CPVI + LAAW group were divided into two sub-groups based on ECG differences following ablation: the BB impairment group and intact BB group. LA activation time and function were then compared between the ablation strategy groups and the CPVI + LAAW subgroups. Patients in the CPVI + LAAW group exhibited longer activation times in the anterior and lateral walls of the LA, poorer LA synchrony, and reduced LA contractile and reservoir function when compared with those in the CPVI group. In the BB impairment subgroup, we observed a discrepancy between electrical/mechanical remodeling. Among five walls, activation time was longest in this region. BB impairment was also associated with reduced LA function. Significant changes in LA function and conductibility were observed in patients with anterior wall ablation, especially those with iatrogenic BB impairment.

Hemodynamic function of the right ventricular-pulmonary vascular-left atrial unit: normal responses to exercise in healthy adults

With each heartbeat, the right ventricle (RV) inputs blood into the pulmonary vascular (PV) compartment, which conducts blood through the lungs at low pressure and concurrently fills the left atrium (LA) for output to the systemic circulation. This overall hemodynamic function of the integrated RV-PV-LA unit is determined by complex interactions between the components that vary over the cardiac cycle but are often assessed in terms of mean pressure and flow. Exercise challenges these hemodynamic interactions as cardiac filling increases, stroke volume augments, and cycle length decreases, with PV pressures ultimately increasing in association with cardiac output. Recent cardiopulmonary exercise hemodynamic studies have enriched the available data from healthy adults, yielded insight into the underlying mechanisms that modify the PV pressure-flow relationship, and better delineated the normal limits of healthy responses to exercise. This review will examine hemodynamic function of the RV-PV-LA unit using the two-element Windkessel model for the pulmonary circulation. It will focus on acute PV and LA responses that accommodate increased RV output during exercise, including PV recruitment and distension and LA reservoir expansion, and the integrated mean pressure-flow response to exercise in healthy adults. Finally, it will consider how these responses may be impacted by age-related remodeling and modified by sex-related cardiopulmonary differences. Studying the determinants and recognizing the normal limits of PV pressure-flow relations during exercise will improve our understanding of cardiopulmonary mechanisms that facilitate or limit exercise.

Left atrial speckle tracking echocardiography in clinically healthy dogs: Variability and prediction intervals

Left atrial (LA) speckle tracking echocardiography (STE) provides indices of LA deformation such as strain and strain rate. These variables offer useful clinical information in human and canine patients with cardiac disease. At present, reference ranges for LA STE variables in dogs are scarcely established and, due to variability among centers, they cannot be accepted worldwide. The present study aimed to provide normal ranges for LA strain and strain rate variables in clinically healthy dogs, and to evaluate the effect of clinical parameters such as bodyweight. Eighty clinically healthy dogs served as the study population. Left atrial STE was feasible in all dogs and agreement within and between observers was clinically acceptable for most of the variables, in particular strain variables. Age, sex, and heart rate did not affect LA STE. Bodyweight was negatively correlated with strain variables and positively correlated with diastolic strain rate variables and the relationship was allometric. Bodyweight-based vendor-dependent prediction intervals for LA STE variables in clinically healthy dogs could aid the evaluation of LA function in clinical practice.

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.

Regional Disparities of Left Atrial Appendage Wall Contraction in Patients With Sinus Rhythm and Atrial Fibrillation

BACKGROUND

Patients with atrial fibrillation (AF) exhibit impaired left atrial appendage (LAA) function. However, regional characteristics of LAA function in patients with AF are not defined.

METHODS

Consecutive patients (n = 1,195) undergoing transesophageal echocardiography at a university hospital were included. Patients were divided into three groups on the basis of their rhythm: sinus rhythm (SR), paroxysmal AF, and permanent or persistent AF. Regional LAA wall velocities were determined using color Doppler tissue imaging, placing regions of interest at the lateral and medial wall of the LAA.

RESULTS

Of the 1,182 patients ultimately included, 691 (59%) were in SR, 371 (32%) had permanent or persistent AF, and 120 (10%) had paroxysmal AF with SR at the time of transesophageal echocardiography. Both lateral and medial LAA wall velocities were lower in patients with AF in comparison with those in SR. Nearly 90% of patients in both groups of patients with AF exhibited a pattern of medial LAA wall velocity greater than lateral LAA wall velocity, in comparison with 20% of patients with SR. The odds ratio for the association of this LAA contraction pattern with AF was 22.14 (95% CI, 12.06-40.64; P < .001). The movement of lateral LAA wall velocity showed the highest correlation with LAA emptying velocity compared with the medial LAA wall (r = 0.67, P < .001).

CONCLUSIONS

Lateral LAA wall velocity is higher than medial LAA wall velocity in patients in SR, which reverses in patients with AF. Assessment of LAA regional wall velocity using Doppler tissue imaging appears to be a promising approach to identify patients with paroxysmal AF.

Left atrial longitudinal strain in dilated cardiomyopathy patients: is there a discrimination threshold for atrial fibrillation?

To determine the left atrial longitudinal strain discrimination threshold of atrial fibrillation (AF) in patients with dilated cardiomyopathy (DCM). A total of 100 DCM patients and LVEF < 25% were included. Of them, 50 had sinus rhythm (SR), and 50 had AF. Patients with significant valvular disease, cardiac pacemakers and prosthetic valves were excluded. Speckle tracking echocardiography was performed to visualize the inferior and lateral walls of the left atrium as well as the interatrial septum. The Q-Analysis software was used to assess left atrial contractile strain (ε_CT) during the atrial systole and left atrial conduit strain (ε_CD) during the atrial filling. In SR patients analysis was P-wave timed. In AF patients the reference point was at 200 ms before the QRS complex on the surface ECG. The ε_CD was significantly higher in SR patients than in those with AF (9.68% vs. 4.7%; p = 0.0003). ROC analysis demonstrated that ε_CD less than 5.43% (AUC 0.95; 95% CI 0.905-0.995; p < 0.0001) together with ε_CT below - 1.97% (AUC = 0.97; 95% CI 0.46-1.00; p < 0.0001) identified patients with AF. In patients with LVEF < 25% and AF left atrial contractile strain analysis is feasible. In these patients both contractile and conduit strain values are significantly lower than in patients with preserved SR, and ε_CD below 5.43% and ε_CT less than - 1.97% distinguish SR from AF patients with LVEF < 25%.

Left atrial size and risk of stroke in patients in sinus rhythm

Little is known about the risk of stroke associated with left atrial enlargement in patients in sinus rhythm, and whether such patients may have an unmet need for thromboprophylaxis. In this systematic review we summarise the existing evidence concerning left atrial size and risk of stroke in patients in sinus rhythm. Nine cohort studies were identified, analysing a total of 67,875 participants and 3,093 stroke outcomes. Rates of stroke per 100 person-years in patients with left atrial enlargement and in sinus rhythm ranged from 0.59 in a population-based cohort to 2.06 in patients referred for echocardiography. All studies reported a higher risk of stroke with larger/enlarged left atrium compared to smaller/normal sized left atrium. Two studies found indications of modification by sex, with only positive associations observed in women. Left atrial enlargement may represent an important predictor of stroke across a variety of patient populations in sinus rhythm. The underlying aetiology explaining this observed higher risk is likely to be multifactorial and not confined to a potential direct effect of left atrial enlargement on thromboembolic risk. Formal stroke risk stratification among patients with left atrial enlargement may further help identify patients who stand to gain from preventive antithrombotic therapy.

Supplementary Material to this article is available online at www.thrombosis-online.com.

The association between right ventricular free wall strain and exercise capacity for health check-up subjects

BACKGROUND

Right ventricular (RV) function has been found to be a major factor of exercise capacity in patients with heart failure. However, the role of RV function in exercise capacity in healthy subjects has not been well studied. This study aims to validate the role of RV strain derived from speckle tracking echocardiography for exercise capacity for health check-up subjects.

METHODS

This study prospectively recruited subjects from a routine health examination. All of them were symptom free. RV function represented by RV strain was derived from speckle tracking echocardiography in addition to traditional echocardiography parameters. Functional capacity was determined by a symptom limited treadmill exercise test with the Bruce protocol.

RESULTS

Among 164 recruited subjects (age 52.2 ±9.2 years, 66.4% male), 32 subjects represented impaired functional capacity (MET<8), which was significantly correlated with age, left ventricular mass index, left ventricular filling pressure (E/e'), global longitudinal strain of the left ventricle (LVGLS) (-16.0±2.5% vs. -18.9±3.8%, p < 0.001) and RV free wall strain (RVLS_FW) (-17.0±4.9% vs. -21.9±3.2%, p <0.001). After multivariate logistic regression, RVS_FW was an independent predictor for impaired functional capacity (OR 1.62, CI 1.32-1.98; p <0.001).

CONCLUSIONS

In conclusion, RV strain is independently associated with exercise capacity for health check-up subjects. RV function is an important factor for functional capacity.

Bayes Syndrome and Imaging Techniques

BACKGROUND

Interatrial block (IAB) is due to disruption in the Bachmann region (BR). According to whether interatrial electrical conduction is delayed or completely blocked through the BR, it can be classified as IAB of first, second or third degree. On the surface electrocardiogram, a P wave ≥ 120 ms (partial IAB) is observed or associated to the prolongation of the P wave with a biphasic (positive / negative) morphology in the inferior leads (advanced IAB). Bayes syndrome is defined as an advanced IAB associated with atrial arrhythmia, more specifically atrial fibrillation. Objective and Conclusion: The purpose of this review is to describe the latest evidence about an entity considered an anatomical and electrical substrate with its own name, which may be a predictor of supraventricular arrhythmia and cardioembolic cerebrovascular accidents, as well as the role of new imaging techniques, such as echocardiographic strain and cardiac magnetic resonance imaging, in characterizing atrial alterations associated with this syndrome and generally in the study of anatomy and atrial function.

Left atrial appendage function assessment and thrombus identification

Background

The diagnosis of thrombus in the left atrium in patients with persistent atrial fibrillation (AF) and may be inconsistent because of variability in thrombus morphology. In some cases it is challenging and requires unusual approach. New Doppler-derived methods might be helpful to identify such thrombi. We evaluated quantitative differences in mechanical function of the left atrial appendage (LAA) basal segments using tissue Doppler imaging (TDI)and speckle tracking echocardiography (STE) in patients with non-valvular AF with and without LAA thrombus and compared them with SR patients.

Methods

A total of 80 patients with normal left ventricular ejection fraction underwent transesophageal echocardiography (40 patients with SR and 40 patients with AF on oral anticoagulants including patients with LAA thrombus). We analyzed the basal segments of LAA including left lateral ridge (LLR) and baso-medial appendage segment (BMAS). Quantitative analysis was used to calculate peak velocity, average velocity, strain, strain rate and deformation.

Results

In patients with AF the lower LLR strain rate was the sole new STE significant parameter differentiating patients with and without LAA thrombi: − 0.9(− 1.2; − 0.1)s^− 1 vs. − 1.6(− 1.9; − 1.3)s^− 1, (p = 0.004). Additionally, patients in SR demonstrated significantly better peak velocity, average velocity, strain, strain rate and deformation than those with AF (p < 0.001).

Conclusions

LLR appeared to be an appropriate site for measuring Doppler derived parameters. It is possible that the strain rate in LLR area may be a novel parameter correlating with the presence of thrombus in patients with AF.

The mitral annular displacement by two-dimensional speckle tracking: a new tool in evaluating the left atrial function

BACKGROUND

The methods used to characterize the volume change and the deformation of the left atrium are highly dependent on technical factors and difficult to use in a clinical environment. The aim of this study was to demonstrate that mitral annular displacement by speckle tracking can be an alternative method to studying the longitudinal left atrial function.

METHODS

Ninety study participants (54% men), with a mean age of 53(±15) years, underwent a complete echocardiographic examination, comprising two-dimensional, three-dimensional and tissue Doppler imaging (TDI). They were divided into normal individuals (35) and patients having an abnormal echocardiography (55).

RESULTS

There was a very strong correlation between three-dimensional volumetric function and mitral annular displacement, both for the reservoir (r = 0.78; P < 0.0001) and contractile (r = 0.76; P < 0.0001) functions. The correlation with the longitudinal strain displayed an r = 0.87, P > 0.0001 for the reservoir and r = 0.81, P < 0.0001 for the contractile function. The systolic speed in pulsed TDI and the systolic displacement had an r = 0.83, P < 0.0001. Mitral annular displacement was a very good discriminator for normal versus abnormal participants [area under the curve (AUC) for reservoir = 0.872 and for contractile = 0.843; P < 0.0001], performing less well than three-dimensional (AUC reservoir = 0.892 and contractile = 0.915; P < 0.0001) or deformation (AUC = 0.921 and 0.903 respectively; P < 0.0001), but better than pulsed TDI (AUC = 0.807; P < 0.0001). The percentage error was ±15% for interobserver and ±12% for intraobserver variability. The time taken for displacement analysis was 9 ± 3 s for an experienced cardiologist and 12 ± 4 s for a beginner.

CONCLUSION

Mitral annular displacement by speckle tracking is a reliable and fast method to evaluate left atrial function. Given the strength of the correlations with strain parameters, it could be used as a surrogate measure of the deformation of left atrium.

Early Detection of Left Atrial Energy Loss and Mechanics Abnormalities in Diabetic Patients with Normal Left Atrial Size: A Study Combining Vector Flow Mapping and Tissue Tracking Echocardiography

Background

Whether left atrial (LA) functional abnormalities already exist when the LA is of normal size is unknown. The aim of this study was to explore LA energy loss and mechanics changes using vector flow mapping (VFM) and two-dimensional tissue tracking (2DTT) echocardiography in patients with diabetes and normal LA size.

Material/Methods

This study included 47 normotensive patients with diabetes and 45 controls. The following indexes were measured: LA energy loss during systole (LAELs), early diastole (LAELed), and atrial contraction (LAELac); atrial longitudinal strain during systole (SLAs), early diastole (SLAed) and late diastole (SLAac); and peak LA strain rate during systole (SRLAs), early diastole (SRLAed), and atrial contraction (SRLAac).

Results

The LAELs and LAELed decreased in diabetic patients compared with controls (P=0.002, P<0.01, respectively), whereas the LAELac increased in diabetic patients (P<0.001). The SLAs, SLAed, SRLAs, and SRLAed (all P<0.01) were all lower in diabetic patients than in controls. However, there was no difference in the SLAac and SRLAac between the two groups. Multivariate regression analysis showed that the LAELs, LAELac, and SRLAs were independently associated with HbA_1c in the whole study population.

Conclusions

LA energy loss and deformation mechanics are already impaired in diabetic patients with normal LA size and the long-term parameter of glycemic control was correlated with them. VFM combined with 2DTT might be a promising tool for the early detection of LA dysfunction caused by impaired glucose metabolism.

Interatrial conduction disturbance in postoperative atrial fibrillation: a comparative study of P-wave dispersion and Doppler myocardial imaging in cardiac surgery

Objective

Disturbances of interatrial conduction have been proposed as one of the contributing mechanisms of postoperative atrial fibrillation (AF). P-wave dispersion has been recognized as a sensitive tool for detecting interatrial conduction disturbances. Doppler myocardial imaging (DMI) has been validated as a non-invasive tool to indirectly reflect electrical atrial activation and therefore is used in this study to detect possible interatrial electromechanical disturbances after cardiac surgery.

Methods

30 patients (23 men, age 62 ± 1 years) admitted for coronary bypass surgery with no prior history of AF were included in this investigation. Echocardiography and electrocardiograms (ECG) were obtained on the day before and after surgery. In addition to standard echocardiography, DMI-loops were acquired from the apical window. The following time intervals were derived off-line from the free right atrial (RA), left atrial (LA) lateral and LA posterior wall: onset P-wave to start (P to A’start), to peak (P to A’peak) and to end of atrial deformation (total electromechanical activity). These intervals were compared to each other and to P-wave dispersion derived from the recorded ECGs.

Results

All patients were in sinus rhythm during their postoperative assessment, but 11 patients presented episodes of AF within the first three postoperative days. Atrial electromechanical activation was earliest in the RA and latest in the lateral LA. In patients with AF, P-wave dispersion was significantly prolonged postoperatively (mean: +18.6 ms; 95% confidence interval (CI): 12.1–25.2 ms; p < 0.001) compared to non-AF patients (mean: -2.4 ms; CI: -6.6–1.9 ms). P dispersion was closely correlated to P to A’start intervals (from RA to LA lat.: preop.: rho = 0.74, postop.: rho = 0.87; p < 0.001). Prolonged right to left conduction interval was associated with an elevated risk for AF (from RA to LA lat.: odds ratio 1.13 (CI:1.03-1.24); p: 0.007.

Conclusion

DMI enabled detection of interatrial conduction disturbances in concordance to findings of prolonged postoperative P-wave dispersion. Equally effective to P-wave dispersion, this simple and reproducible tool might help to early identify the risk for postoperative AF, thus extending the informative value of routine postoperative echocardiography.

Evaluation of biatrial size and functions by different echocardiographic parameters in patients with acute coronary syndromes

After acute coronary syndromes (ACS), cardiac remodelling affecting not only ventricles but also both atria is an important problem associated with an increased risk for adverse cardiovascular outcomes. However, it is usually underestimated to evaluate atrial size and functions. The aim of the present study is to compare left and right atrial size and functions in ACS patients with healthy controls during transthoracic echocardiography by means of diameter, area and volume measurements, and pulsed-wave tissue Doppler imaging (TDI). 150 ACS patients (128 male, 22 female) and 25 healthy controls (19 male, 6 female) were enrolled into the study. Of the ACS patients, 75 had ST-segment elevation myocardial infarction (STEMI) and 75 had non-STEMI. Biatrial diameters, areas, and volumes were measured from different echocardiographic views. Atrial total emptying fraction and expansion index values were calculated from volume measurements. By the pulsed-wave TDI of the atrial walls; peak systolic (S'), peak early diastolic (E'), and peak late diastolic (A') velocities were measured. Almost all left atrial parameters for diameter, area, and volume measurements were higher in ACS patients. Similarly, they had higher values for the same right atrial parameters. Left and right atrial total emptying fraction and expansion index values were lower in ACS patients than controls. All left and right atrial walls had lower S' and E' velocities in ACS patients. ACS cause important alterations in the biatrial size and functions evaluated by echocardiographic diameter, area and volume measurements, and pulsed-wave TDI.

Long-term follow-up of atrial function after cardioversion of atrial fibrillation in horses

Atrial fibrillation (AF) causes atrial electrical and contractile remodelling in horses. The aim of this study was to quantify left atrial (LA) contractile function and its time course of recovery after cardioversion of naturally-occurring AF in horses. The study population included 42 AF horses which were successfully treated using transvenous electrical cardioversion TVEC (n=39) or quinidine sulfate (n=3), with trivial or mild mitral regurgitation present in 25 horses. Thirty-seven healthy horses were used as controls. AF duration was estimated based on the history and previous examinations. Echocardiography was performed during general anaesthesia after TVEC (day 0) and on days 1, 2, 6 and then 7 weeks after cardioversion. The two-dimensional (2D) echocardiographic measurements included LA diameter, area and ejection phase indices such as fractional shortening. Atrial TDI measurements included peak myocardial velocity during atrial contraction (A), time to onset A, time to peak A and duration of A. During follow-up after cardioversion, atrial contractile function measured by 2D echocardiography and TDI gradually improved. At 7 weeks following cardioversion, TDI-based myocardial velocities returned to reference values. However, AF horses still showed significantly larger atrial dimensions, lower 2D ejection phase indices and prolonged TDI-based conduction time compared to the control group. In conclusion, AF-induced atrial contractile dysfunction gradually improves in the weeks following cardioversion, but at 7 weeks post-cardioversion, significant differences remain compared to healthy controls.

New echocardiographic techniques for evaluation of left atrial mechanics

Until recently the left atrium had been subordinate to the left ventricle, but cardiologists now recognize that left atrial (LA) function is indispensable to normal circulatory performance. Transthoracic two-dimensional (2D) and Doppler echocardiography can elucidate parameters of LA function non-invasively. Yet, with the advent of 2D speckle-tracking echocardiography, we are able to detect early LA dysfunction even before structural changes occur. This is pivotal in some common disease states, such as atrial fibrillation, hypertension, and heart failure, in which LA deformation parameters can influence clinical management. However, a unique standardized technique to investigate LA deformation needs to be validated.

Left atrial function: physiology, assessment, and clinical implications

The interest in the left atrium (LA) has resurged over the recent years. In the early 1980s, multiple studies were conducted to determine the normal values of LA size. Over the past decade, LA size as an imaging biomarker has been consistently shown to be a powerful predictor of outcomes, including major public health problems such as atrial fibrillation, heart failure, stroke, and death. More recently, functional assessment of the LA has been shown to be, at least as, if not more robust, a marker of cardiovascular outcomes. Current available data suggest that the combined evaluation of LA size and LA function will augment prognostication. The aim of this review is to provide a critical appraisal of current echocardiographic techniques for the assessment of LA function and the implications of such assessment for prediction and disease prevention.

The effects of spironolactone on atrial remodeling in patients with preserved left ventricular function after an acute myocardial infarction: a randomized follow-up study

OBJECTIVES

Atrial remodeling is an important part of cardiac remodeling after acute myocardial infarction (AMI). The aim of this study was to evaluate the effect of spironolactone on atria in patients with preserved left ventricular (LV) functions after AMI by using two-dimensional and tissue Doppler imaging techniques (TDI).

METHODS

The study consisted of 110 patients with AMI, successfully revascularized with percutaneous coronary intervention, ejection fraction greater than or equal to 40%, and Killip class I-II. Patients were randomized into two groups: conventional therapy (n=55) and additional spironolactone of 25 mg/day with standard conventional therapy (n=55). Echocardiography was performed in the first 48-72 h of AMI and during 6 months of follow-up. Left atrial volume index and emptying fraction were obtained. The peak regional atrial contraction velocity, the time between the onset of p-wave on the monitor ECG and the onset, peak, and the end (TE) of the atrial contraction wave on the tissue Doppler technique curve were measured.

RESULTS

The left atrial volume index and left atrium (LA) dimensions did not significantly change in either group. In the spironolactone group, left atrial emptying fraction increased compared with both baseline value (from 53.0 ± 0.16 to 57.0 ± 0.13 P=0.011) and conventional therapy group (from 50.0 ± 0.17 to 47.0 ± 0.16, P=0.013). The atrial contraction velocity did not change but the LA-TE, interatrial septum-TE, and right atrium-TE were prolonged in the conventional therapy group.

CONCLUSION

Additional spironolactone therapy provided a little benefit on LA remodeling and atrial electromechanic properties in patients with AMI and preserved LV functions.

Assessment of myocardial mechanics using speckle tracking echocardiography: fundamentals and clinical applications

The authors summarize the recent developments in speckle-tracking echocardiography (STE), a relatively new technique that can be used in conjunction with two-dimensional or three-dimensional echocardiography for resolving the multidirectional components of left ventricular (LV) deformation. The tracking system is based on grayscale B-mode images and is obtained by automatic measurement of the distance between 2 pixels of an LV segment during the cardiac cycle, independent of the angle of insonation. The integration of STE with real-time cardiac ultrasound imaging overcomes some of the limitations of previous work in the field and has the potential to provide a unified framework to more accurately quantify the regional and global function of the left ventricle. STE holds promise to reduce interobserver and intraobserver variability in assessing regional LV function and to improve patient care while reducing health care costs through the early identification of subclinical disease. Following a brief overview of the approach, the authors pool the initial observations from clinical studies on the development, validation, merits, and limitations of STE.

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.

Right atrium contractility and right ventricular diastolic function assessed by pulsed tissue Doppler imaging can predict brain natriuretic peptide in adults with acquired pulmonary hypertension

PURPOSE

We evaluated right atrial (RA) contractility and right ventricular (RV) diastolic function in adult patients with acquired chronic pulmonary hypertension (PH) by pulsed Tissue Doppler Imaging (TDI) and assessed their relationship with serum brain natriuretic peptide (BNP).

MATERIALS AND METHODS

Systolic myocardial wave (Sa), early diastolic myocardial wave (Ea), and late diastolic myocardial wave (Aa) at the tricuspid annulus were recorded in 77 consecutive patients with acquired PH. Early (E) RV inflow waves were recorded from 4-chamber views. RV Aa was regarded as the parameter of RA contractility and RV E/Ea was taken as the parameter of RV diastolic function using TDI.

RESULTS

All subjects had elevated BNP (mean 188.9 +/- 244.0 pg/dl) and pulmonary arterial systolic pressure (PASP) estimated at 62.9 +/- 26.7 mm Hg. BNP levels were positively correlated with RV E/Ea, Aa and PASP (r = 0.47, p < 0.0001 and r = 0.35, p < 0.01, respectively) but negatively with Aa (r = -0.29, p < 0.05). Next, all predictor variables were used in a multiple regression model with serum BNP values as dependent variables, refined to include 3 predictors: RV E/Ea, Aa, and PASP, which were all found to influence serum BNP values (p < 0.0001) by the formula Y = 34.1X1**-19.11X2**+2.95X3* (**p < 0.001, *p < 0.01) where Y = BNP, X1 = E/Ea of RV, X2 = Aa, and X3 = PASP (standard regression coefficients were 0.37, -0.34 and 0.34, respectively).

CONCLUSION

Serum BNP correlates with RA contractility and RV diastolic dysfunction by RV TDI in adults with acquired PH. Increased BNP may be related to decreased RA systolic function and RV diastolic function in these patients.

Multi-modality imaging to assess left atrial size, anatomy and function

The left atrium (LA) anterior-posterior diameter was one of the first standardised echocardiographic parameters. However, the clinical importance of LA size assessment has been neglected for some time. Recent population-based studies have demonstrated the prognostic value of LA size for long-term outcome. Furthermore, with new dedicated techniques such as tissue Doppler imaging, it has become feasible to assess (regional) LA function. In addition, the introduction of catheter ablation procedures has changed the treatment of patients with drug-refractory atrial fibrillation (AF) dramatically. New image integration systems have become available for these catheter ablation procedures. With the use of image integration systems, a real anatomical "roadmap" of the LA is provided for catheter ablation procedures. All these factors may explain the renewed interest in LA anatomy. In this article, the importance of assessment of LA size and LA anatomy is discussed. Furthermore, the various imaging modalities that are available for the non-invasive visualisation of the LA will be reviewed. In addition, the role of these imaging techniques in catheter ablation procedures for AF will be discussed.

Methods and reliability of echocardiographic assessment of left atrial size and mechanical function in horses

OBJECTIVE

To assess the feasibility, describe the techniques, and determine the reliability of transthoracic echocardiography for characterization of left atrial (LA) size and LA mechanical function in horses.

ANIMALS

6 healthy adult horses.

PROCEDURES

Repeated echocardiographic examinations were performed independently by 2 observers in standing, unsedated horses by use of 2-dimensional echocardiography, pulsed-wave flow Doppler, and tissue Doppler imaging (TDI) techniques. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day inter- and intraobserver variability of all echocardiographic variables. Variability was expressed as the coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability.

RESULTS

Most echocardiographic variables of LA size had low overall variability (CV, < 15%). Among the 2-dimensional indices of LA mechanical function, area-based and volume-based ejection phase indices had moderate between-day variability (CV usually < 25%). Transmitral Doppler flow indices were characterized by low to high between-day variability (CV, 6% to 35%). The TDI wall motion velocities had high between-day variability (CV, > 25%), whereas most TDI-derived time intervals had low variability (CV, < 15%).

CONCLUSIONS AND CLINICAL RELEVANCE

LA size and mechanical function can be reliably assessed in standing, unsedated horses by use of 2-dimensional echocardiography, transmitral blood flow velocity profiles, and analyses of LA wall motion by use of TDI. These results may provide useful recommendations for echocardiographic assessment of LA size and function in horses.

Striving towards the ideal cardiac functional assessment strategy: the contribution of tissue Doppler, strain and strain rate imaging

In cardiac research, a major goal of prevention of catastrophic events by risk-factor management and earlier detection has, in recent years, led to a proliferation of imaging modalities, moving us from old-fashioned chest X-ray through increasingly sophisticated approaches such as magnetic resonance imaging (MRI) and multi-slice fast computer-aided tomography (CT) scanning. Today, we have the option of using a vast array of invasive and non-invasive approaches, with diverse technical underpinnings, to assess various, and often overlapping aspects of cardiac function. Tissue Doppler imaging (TDI) and the related applications of strain and strain rate imaging are new technologies that are now being evaluated in the realm of practical patient care, and the underlying principles remind us that cardiac contractility is a reflection of the integration of muscle fibre architecture, mechanics and metabolism. TDI is the first technology that allowed imaging of motion within the myocardial wall rather than that of the blood pool, and permits analysis of velocities and accelerations from ultrasonic scatterers in muscle. Since its inception, it has been used to evaluate both new cardiac functional parameters as well as conventional function; for some of these, TDI has proven the superior imaging modality, while for others it offers only incremental information over conventional approaches.

Atrial strain rate echocardiography can predict success or failure of cardioversion for atrial fibrillation: A combined transthoracic tissue Doppler and transoesophageal imaging study

AIMS

The purpose of this study was to assess the feasibility of measuring left atrial dysfunction with tissue Doppler imaging derived strain rate and to explore its role in predicting the maintenance of sinus rhythm after cardioversion for atrial fibrillation.

METHODS AND RESULTS

Strain rate (SR) and tissue Doppler imaging (TDI) were performed with offline analysis of the basal left atrial wall (LA). SR detected a systolic (Ssr) and early diastolic (Esr) deformation induced by ventricular motion. LA dimensions and volume were measured. Left atrial appendage emptying (LAA_EV) and filling (LAA_FV) velocities were also obtained by transesophageal echocardiography. 27 healthy age-matched controls and 42 patients with AF before cardioversion were studied. Patients were grouped into (1): those who remained in sinus rhythm (group S, n=12) and (2) those who either failed cardioversion or reverted to AF within 4 weeks (group F, n=30). LA dimensions were significantly larger and atrial Esr was significantly lower in group F than group S (all p<0.01). LAA_EV and LAA_FV were not different between groups S and F. Multivariate regression analysis showed that a lower Esr and larger transverse LA diameter (LADtr) were independent predictors of failure of cardioversion (HR, 95% CI: 0.36, 0.14-0.88 and 2.85, 1.33-6.10, respectively). Esr combined with LADtr improved the sensitivity and specificity for predicting successful cardioversion.

CONCLUSIONS

SR can be measured in the basal LA wall in atrial fibrillation and the magnitude of the early diastolic SR could predict the success of cardioversion and the likelihood of maintenance of sinus rhythm.

Effect of Age and Heart Rate on Atrial Mechanical Function Assessed by Doppler Tissue Imaging in Healthy Individuals

BACKGROUND

The potential usefulness of Doppler tissue imaging (DTI) to assess atrial mechanical function in cardiac disease has been demonstrated. However, there are few reports on normal values of atrial function by DTI analysis.

METHODS

Echocardiography with color-coded DTI was performed in 131 healthy control subjects. The peak atrial contraction velocity (V(A)) and the timing of mechanical events were assessed offline at the left atrial (LA) and right atrial (RA) free wall and interatrial septum.

RESULTS

V(A) was higher in the RA (9.0 +/- 2.6 cm/s) than the LA (7.5 +/- 2.4 cm/s, P < .001), and both sites were higher than the interatrial septum (5.6 +/- 1.3 cm/s, both P < .001). The interatrial delay was 24 +/- 21 milliseconds. V(A) at the LA was higher in the participants aged 60 years or older than those who were younger than 60 years (8.1 +/- 2.7 vs 6.7 +/- 1.4 cm/s, P < .001), as was the velocity at the RA (9.6 +/- 2.8 vs 8.0 +/- 2.1 cm/s, P < .01). V(A) at the LA was higher in the participants with heart rate of 60/min or higher than those with lower heart rate (7.9 +/- 2.5 vs 6.8 +/- 1.8 cm/s, P < .05). Sex difference had no effect on V(A) and timings of atrial events.

CONCLUSIONS

Assessment of atrial mechanical function by DTI is feasible in healthy individuals. The V(A) is the highest at the RA, followed by LA, and the lowest at the interatrial septum. Older age and faster heart rate seems to augment V(A) in the atrial walls.