Left atrial mechanical function in the healthy elderly: new insights from a combined assessment of changes in atrial volume and transmitral flow velocity

Atrial dilation and altered function are mediated by age and diastolic function but not before the eighth decade

OBJECTIVES

This study investigated changes in left atrial (LA) volumes and phasic atrial function, by deciles, with normal aging.

BACKGROUND

LA volume increase is a sensitive independent marker for cardiovascular disease and adverse outcomes. To use this variable more effectively as a marker of pathology and a gauge of outcome, physiological changes due to aging alone need to be quantitated.

METHODS

A detailed transthoracic echocardiogram was performed in 220 normal subjects; 89 (41%) were male and their age ranged from 20 to 80 years (mean 45 ± 17 years). Maximum (end-ventricular systole), minimum (end-ventricular diastole), and pre-a-wave volumes were measured using the biplane method of disks. LA filling, passive emptying, conduit and active emptying volumes, and fractions were calculated. Transmitral inflow, pulmonary vein flow, and pulsed-wave Doppler tissue imaging parameters were measured as expressions of left ventricular diastolic function. For purposes of analysis, subjects were divided by age deciles.

RESULTS

LA indexed maximum (0.05 ml/m(2) per year) and minimum (0.06 ml/m(2) per year) volume increased with age but only became significant in the eighth decade (26.0 ± 6.3 ml/m(2), p = 0.02, and 13.5 ± 3.9 ml/m(2), respectively; p < 0.001). Impaired left ventricular diastolic relaxation was apparent in decade 6 and was associated with a shift in phasic LA volumes so that LA expansion index and passive emptying decreased with increasing age, whereas active emptying volume increased.

CONCLUSIONS

In normal healthy subjects, LA indexed volumes remain nearly stable until the eighth decade when they increase significantly. Therefore, an increase in LA size that occurs before the eighth decade is likely to represent a pathological change. Changes in phasic atrial volumes develop earlier consequent to age-related alteration in LV diastolic relaxation.

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.

Left atrial systolic and diastolic dysfunction in heart failure with normal left ventricular ejection fraction

BACKGROUND

The authors hypothesized that in patients with heart failure with normal left ventricular (LV) ejection fraction (HFNEF), the same fibrotic processes that affect the subendocardial layer of the left ventricle could also alter the subendocardial fibers of the left atrium. Consequently, these fibrotic alterations, together with chronically elevated LV filling pressures, would lead to both systolic and diastolic subendocardial dysfunction of the left atrium (i.e., impaired left atrial [LA] longitudinal systolic and diastolic function) in patients with HFNEF.

METHODS

Patients with HFNEF and a control group consisting of asymptomatic patients with LV diastolic dysfunction (LVDD) matched by age, gender, and LV ejection fraction were studied using two-dimensional speckle-tracking echocardiography.

RESULTS

A total of 420 patients were included (119 with HFNEF and 301 with asymptomatic LVDD). LA longitudinal systolic (LA late diastolic strain rate) and diastolic (LA systolic strain and strain rate) function was significantly more impaired in patients with HFNEF (LA late diastolic strain rate, -1.17 ± 0.63 s(-1); LA systolic strain, 19.9 ± 7.3%; LA systolic strain rate, 1.17 ± 0.46 s(-1)) compared with those with asymptomatic LVDD (-1.80 ± 0.70 s(-1), 30.8 ± 11.4%, and 1.67 ± 0.59 s(-1), respectively) (all P values < .0001). On multiple regression analysis, LV global longitudinal systolic strain and diastolic strain rate were the most important independent predictors of LA longitudinal systolic and diastolic function, in contrast to noninvasive LV filling pressures (i.e., mitral E/e' average septal-lateral ratio), which were modestly related to LA longitudinal systolic and diastolic function. Furthermore, in patients with HFNEF, the subendocardial function of both the left atrium and the left ventricle was significantly impaired in high proportions. In that regard, in patients with HFNEF, the rate of LA longitudinal systolic and diastolic dysfunction was 65.5% and 28.5%, whereas the prevalence of LV longitudinal systolic and diastolic dysfunction was 81.5% and 58%, respectively. In addition, patients with both systolic and diastolic longitudinal dysfunction of the left atrium presented worse NYHA functional class as compared with those with normal LA longitudinal function.

CONCLUSIONS

In patients with HFNEF, LA subendocardial systolic and diastolic dysfunction is common and possibly associated with the same fibrotic processes that affect the subendocardial fibers of the left ventricle and to a lesser extent with elevated LV filling pressures. Furthermore, these findings suggest that LA longitudinal systolic and diastolic dysfunction could be related to reduced functional capacity during effort in patients with HFNEF.

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

AIM

We assessed left atrial appendage (LAA) function using transthoracic tissue Doppler echocardiography (TDE), and examined the influence of aging on LAA contraction and relaxation.

METHODS

The subjects were 45 consecutive patients with heart disease and 110 healthy individuals. LAA wall motion velocity (LAAWV) at the tip of the LAA was measured using transthoracic echocardiography (TTE) and/or transesophageal echocardiography (TEE).

RESULTS

We successfully recorded and measured LAAWV using TTE in 105 (95%) of the 110 healthy subjects. When angle correction was applied for the Doppler beam in TTE, LAAWV during contraction (LAAWVc) measured by TTE closely correlated with that measured by TEE (r = 0.97), and LAAWV during relaxation (LAAWVr) measured by TTE closely correlated with that measured by TEE (r = 0.95). LAAWVc and LAAWVr measured by TTE correlated significantly with the LAA flow velocities during LAA contraction and LAA relaxation measured by TEE (r = 0.64, P < 0.001; r = 0.53, P = 0.001). In healthy subjects, although LAAWVc remained unchanged with aging, LAAWVr significantly declined with aging (r =-0.48, P < 0.001) and had a significant negative correlation with left atrial dimension and a significant positive correlation with transmitral flow and annulus velocity during early diastole.

CONCLUSION

Transthoracic TDE can provide information on LAA function. LAA relaxation may be impaired with aging and may be accompanied by early diastolic left ventricular dysfunction and chronic overload to the left atrium.

Longitudinal tracking of left atrial diameter over the adult life course: Clinical correlates in the community

BACKGROUND

Increased left atrial diameter (LAD) is associated with elevated risk of atrial fibrillation (AF) and cardiovascular disease. Information is limited regarding the short- or long-term correlates of LAD.

METHODS AND RESULTS

We evaluated clinical correlates of LAD for a 16-year period in 4403 Framingham Study participants (mean age, 45 years; 52% women; median observations/participant=3) using multilevel modeling. We related age, sex, body mass index (BMI), systolic and diastolic blood pressure (BP), diabetes, and antihypertensive treatment to LAD. Sex-specific growth curves for LAD were estimated for individuals with low, intermediate, and high risk factor burden. We also related risk factors to changes in LAD during a 4-year period in 3365 participants. Age, male sex (3.83 mm compared to women), greater BMI, higher systolic BP (0.24 mm per 10 mm Hg increment), and antihypertensive treatment (0.54 mm) were associated positively with LAD (P<0.001). Men had a greater increase in LAD with BMI than women (2.02 versus 1.77 mm in women, per 5-unit increment), and individuals receiving antihypertensive treatment experienced a greater increase in LAD with age (0.95 versus 0.63 mm per 10-year age increment) when compared with those not receiving antihypertensive treatment. Overall, greater risk factor burden was positively associated with LAD. These risk factors were also associated positively with 4-year change in LAD (P<0.001).

CONCLUSIONS

Our longitudinal study of a large community-based sample identified higher BP and greater BMI as key modifiable correlates of LAD, suggesting that maintaining optimal levels of these risk factors through the life course may prevent atrial remodeling and AF.

Diastolic dysfunction, cardiovascular aging, and the anesthesiologist

As the number of persons aged 65 years and older continues to increase, the anesthesiologist will more frequently encounter this demographic. Cardiovascular changes that occur in this patient population present difficult anesthetic challenges and place these patients at high risk of perioperative morbidity and mortality. The anesthesiologist should be knowledgeable about these age-related cardiovascular changes, the pathophysiology underlying them, and the appropriate perioperative management. Whether presenting for cardiac or general surgery, the anesthesiologist must identify patients with altered physiology as a result of aging or diastolic dysfunction and be prepared to modify the care plan accordingly. With a directed preoperative assessment that focuses on certain aspects of the cardiovascular system, and the assistance of powerful echocardiographic tools such as tissue Doppler, this can be achieved.

Echocardiographic assessments of left atrial strain and volume in healthy patients and patients with mitral valvular heart disease by tissue Doppler imaging and 3-dimensional echocardiography

Background and Objectives

The purpose of the current study was to assess left atrial (LA) physiology in relation to associations between LA volume change and regional tissue velocities and strains, and to extend this information to patients with mitral stenosis (MS) or mitral regurgitation (MR).

Subjects and Methods

Twenty-two healthy persons, 22 patients with moderate-to-severe MS, and 22 patients with moderate-to-severe MR were studied. Tissue velocities, strains, and time-volume curves of the LA were acquired using tissue Doppler imaging and 3-dimensional echocardiography.

Results

In healthy controls, the maximal LA volume was negatively correlated with the posterior wall longitudinal systolic strain (r=-0.45, p=0.03). The time-to-maximal LA volume was positively correlated with the time-to-posterior wall longitudinal peak strain (r=0.46, p=0.03) and the time-to-circumferential peak strain (r=0.59, p=0.004). The LA active emptying fraction (LAactEF) was positively correlated with the posterior wall longitudinal peak systolic and late diastolic tissue velocities. In patients with MS, the maximal LA volume was negatively correlated with the posterior wall radial peak systolic velocity and the longitudinal late diastolic velocity. In patients with MS, the LAactEF had an additional positive correlation with the anterior wall longitudinal and circumferential systolic velocities, whereas the patients with MR had an additional positive correlation between the LAactEF and the lateral wall longitudinal peak strain as compared with the healthy cantrols.

Conclusion

LA longitudinal and circumferential deformations are more related than radial deformation to determining LA volume and function. The LA of patients with MS revealed a greater pathologic physiology than those of patients with MR.

Determinants of enhanced left atrial active emptying with aging: left atrial preload, contractility or both?

OBJECTIVE

Senile persons have reduced left ventricular (LV) relaxation and increased late diastolic filling. However, the determinant factor of the enhanced active emptying of the left atrium has not been well established.

METHODS

Subjects were 62 healthy individuals with a mean age of 58+/-19 (21-85) years. The biplane modified Simpson's rule was applied to measure left atrial (LA) volume at pre-atrial contraction (LAVpre) as an index of LA preload and LA volume change during atrial contraction (LASV) as an index of active LA emptying. These values were divided by the body surface area and represented as LAVpreI and LASVI, respectively. Postero-basal (dorsal cranial) left atrial wall velocity (LAWV) during atrial contraction as an index of LA contractility was measured in the apical three-chamber view by two-dimensional tissue Doppler echocardiography.

RESULTS

Age significantly correlated with mitral flow velocity (TMA), velocity-time integral during atrial contraction (TMAVTI) and LASVI (r= 0.63, p<0.001 and r=0.71, p<0.001, r=0.21, p=0.049, respectively). LAVpreI was significantly correlated with age (r=0.44, p<0.001), LASVI (r=0.71, p<0.001), TMA (r=0.31, p=0.008) and TMAVTI (r=0.40, p<0.001). LAWV remained unchanged with aging and had no correlation with TMA, TMAVTI or LASVI.

CONCLUSION

The enlargement of the LA in senile persons may be a major determinant of enhanced active LA emptying and the increased LA contractility may be less contributory.

Echocardiographic evaluation of left atrial size and function: current understanding, pathophysiologic correlates, and prognostic implications

Left atrial (LA) volume has recently been identified as a potential biomarker for cardiac and cerebrovascular disease. However, evidence regarding the prognostic implications of LA volume still remains unclear. Evaluation of LA size and function using traditional and more recent echocardiographic parameters is potentially feasible in the routine clinical setting. This review article discusses the conventional and newer echocardiographic parameters used to evaluate LA size and function. Conventional parameters include the assessment of phasic atrial activity using atrial volume measurements, transmitral Doppler peak A velocity, atrial fraction, and the atrial ejection force. Newer parameters include Doppler tissue imaging (DTI) including segmental atrial function assessment using color DTI, strain, and strain rate. In addition, an overview of the implications and clinical relevance of the findings of an enlarged left atrium, from currently available literature, is presented.

Significance of left atrial volume in patients < 20 years of age with hypertrophic cardiomyopathy

Left atrial (LA) enlargement is an indicator of chronic elevation in left ventricular (LV) end-diastolic pressure as well as diastolic dysfunction. There is a lack of data on the significance of LA volume in the pediatric population. The objective of this study was to elucidate the relation between LA volume and diastolic dysfunction, clinical symptoms, and exercise capacity in young patients with hypertrophic cardiomyopathy. All patients aged <20 years with obstructive hypertrophic cardiomyopathy who underwent evaluation at the Mayo Clinic from 2002 to 2006 were retrospectively identified. Reviews of the LA volume index and other traditional diastolic Doppler echocardiographic parameters, as well as clinical data, were performed. A total of 88 patients (66 male) were studied. The median age at evaluation was 14 years. The mean LA volume index was 39 +/- 19 ml/m(2). Additional echocardiographic parameters included a mean LV outflow gradient of 55 +/- 51 mm Hg, a mean E/E' ratio of 14.0 +/- 7.6, and a mean maximal septal wall thickness of 23 +/- 9 mm. On univariate linear regression analysis, LA volume index had an excellent correlation with diastolic dysfunction grade (p <0.001, r(2) = 0.6), LV outflow tract gradient, mitral E/E', and the degree of mitral regurgitation. LA volume index was also positively associated with symptom score (p = 0.005) and maximal oxygen consumption on exercise test (n = 22; p = 0.01). On multivariate analysis, LA volume index was related to diastolic dysfunction grade (p <0.001) and mean mitral regurgitation grade (p = 0.05). In conclusion, this study demonstrates the potential clinical importance of LA volume index in pediatric hypertrophic cardiomyopathy as a marker of the severity of underlying diastolic dysfunction, symptom score, and decreased exercise capacity. LA volume index has significant diagnostic and prognostic value in these patients.

WITHDRAWN: Left atrial function and arterial hypertension

Left atrial enlargement is frequently observed in many cardiac diseases. One of the main determinants of left atrial size is ventricular diastolic function. It has recently been suggested that left atrial volume might be the morphophysiologic expression of long-term modifications induced by diastolic function. Furthermore, left ventricular remodelling, such as it happens in hypertensive patients, is another important determinant of atrial volume. All the volumetric modifications of the left atrium, during cardiac cycle, are involved in hypertensive damage. Therefore, left atrial function impairment represents the result of morphological and haemodynamic alterations observed in hypertension. Actually, many techniques, invasive and non-invasive, are available with the purpose to investigate the real atrial dimensions and provide a suitable assessment of atrial function. Recently, it has been demonstrated that the degree of left atrial enlargement is associated with adverse prognosis in different clinical setting. The predictive value of left atrial volume seems to be independent of left ventricular systolic and diastolic function, but the use of left atrial volume for risk stratification is yet an evolving science: more data are required with respect to the natural history of left atrial remodelling in disease, the degree of left atrial modifiability with therapy and whether regression of left atrial size translates into improved cardiovascular outcome.Journal of Human Hypertension advance online publication, 14 August 2008; doi:10.1038/jhh.2008.96.

Left atrial reservoir function as a potent marker for first atrial fibrillation or flutter in persons > or = 65 years of age

The aim of this prospective study was to evaluate the incremental value of left atrial (LA) function for the prediction of risk for first atrial fibrillation (AF) or atrial flutter. Maximum and minimum LA volumes were quantitated by echocardiography in 574 adults (mean age 74 +/- 6 years, 52% men) without a history or evidence of atrial arrhythmia. During a mean follow-up period of 1.9 +/- 1.2 years, 30 subjects (5.2%) developed electrocardiographically confirmed AF or atrial flutter. Subjects with new AF or atrial flutter had lower LA reservoir function, as measured by total LA emptying fraction (38% vs 49%, p <0.0001) and higher maximum LA volumes (47 vs 40 ml/m(2), p = 0.005). An increase in age-adjusted risk for AF or atrial flutter was evident when the cohort was stratified according to medians of LA emptying fraction (< or =49%: hazard ratio 6.5, p = 0.001) and LA volume (> or =38 ml/m(2): hazard ratio 2.0, p = 0.07), with the risk being highest for subjects with concomitant LA emptying fractions < or =49% and LA volume > or =38 ml/m(2) (hazard ratio 9.3, p = 0.003). LA emptying fraction (p = 0.002) was associated with risk for first AF or atrial flutter after adjusting for baseline clinical risk factors for AF or atrial flutter, left ventricular ejection fraction, diastolic function grade, and LA volume. In conclusion, reduced LA reservoir function markedly increases the propensity for first AF or atrial flutter, independent of LA volume, left ventricular function, and clinical risk factors.

Possible beneficial effect of olmesartan medoxomil on left atrial function in patients with hypertension : noninvasive assessment by acoustic quantification

BACKGROUND AND OBJECTIVE

Hypertension alters the diastolic properties of the left ventricle and results in deterioration in the structure and function of the left atrium. We aimed to evaluate whether olmesartan medoxomil has an effect on left atrial function in hypertensive patients.

METHODS

Fifty hypertensive patients and 20 controls were included in the study. Hypertensive patients were treated with olmesartan medoxomil for 8 weeks. Before and after treatment, study participants were examined by acoustic quantification and tissue Doppler imaging. Left atrial reservoir function was assessed by end-diastolic volume (EDV), end-systolic volume (ESV), reservoir volume (RV) and peak filling rate (PFR). Left atrial booster pump function was assessed by atrial emptying volume (AEV), atrial emptying fraction (AEF) and peak atrial emptying rate (PAER). Left atrial conduit function was assessed by rapid emptying volume (REV), rapid emptying fraction (REF), REV/AEV ratio, and the ratio of peak rapid emptying rate and PAER (PRER/PAER).

RESULTS

Atrial RV and PFR were significantly increased in hypertensive subjects (48.30 +/- 19.28 mL vs 34.35 +/- 14.26 mL, p < 0.001; 267.26 +/- 126.52 mL/s vs 206.81 +/- 107.17 mL/s, p < 0.05) compared with controls, while the REV/AEV ratio was decreased in hypertensive patients compared with controls (2.86 +/- 0.85 vs 3.69 +/- 2.13, p < 0.001). After therapy with olmesartan medoxomil, atrial RV (48.30 +/- 19.28 mL vs 40.50 +/- 17.59 mL) and PFR decreased (267.26 +/- 126.52 mL/s vs 220.40 +/- 108.56 mL/s, p < 0.05) and the REV/AEV ratio increased (2.86 +/- 0.85 vs 3.14 +/- 0.43, p < 0.05) in hypertensive patients.

CONCLUSION

Our novel findings indicate that left atrial function is impaired in hypertensive patients, and that olmesartan medoxomil can improve left atrial function in this context. Our study also showed that acoustic quantification is useful for non-invasive evaluation of the benefits of treatment on left atrial function.

Structural and functional remodeling of the left atrium: clinical and therapeutic implications for atrial fibrillation

Left atrial (LA) structural and functional remodeling reflects a spectrum of pathophysiological changes that have occurred in response to specific stressors. These changes include alterations at the levels of ionic channels, cellular energy balance, neurohormonal expression, inflammatory response, and physiologic adaptations. There is convincing evidence demonstrating an important pathophysiological association between LA remodeling and atrial fibrillation (AF). Measures that will prevent, attenuate, or halt these processes of LA remodeling may have a major public health impact with respect to the epidemic of AF. In this review, we describe the mechanisms involved in LA remodeling and highlight the existing and potential therapeutic options for its reversal, and implications for AF development.

Assessment of Atrial Function

This article discusses the traditional and more recent echocardiographic measures that have been employed to evaluate atrial function. Conventional parameters commonly used and reported in the literature include the study of the various phases of atrial activity using atrial volume measurements, the peak A wave velocity, its velocity time integral (VTI) and the fraction of atrial contribution (all obtained from transmitral flow), as also the atrial ejection force. Newer parameters for atrial function assessment include Doppler tissue imaging (DTI) including segmental atrial contractility using colour Doppler tissue imaging (CDTI) and estimates of atrial strain and strain rate.

Left atrial remodelling contributes to the progression of asymptomatic left ventricular systolic dysfunction to chronic symptomatic heart failure

Systolic heart failure (HF) is a progressive disorder that often begins with asymptomatic left ventricular (LV) systolic dysfunction and culminates in symptoms from fluid overload and poor end-organ perfusion. The progression to symptomatic HF is accompanied by marked activation of neurohormonal and cytokine systems, as well as a series of adaptive LV anatomical and functional changes, collectively referred to as LV remodelling. However, the mechanisms underlying symptom appearance have not been delineated and the weight of experimental and clinical evidence suggests that the development of symptomatic HF occurs independently of the haemodynamic status of the patient. The left atrium is a muscular chamber strategically located between the left ventricle and the pulmonary circulation with important mechanical function (modulation of LV filling), which is closely coupled with its endocrine (atrial natriuretic peptide synthesis and secretion) and regulatory (contribution to the control of sympathetic activity and vasopressin release) functions. In this narrative review we provide evidence supporting the concept that left atrial dilation and systolic dysfunction (left atrial remodelling) contributes to the progression of asymptomatic LV dysfunction to chronic symptomatic systolic HF as it is a prerequisite for the development of the pulmonary congestion and marked neuronhormoral activity that characterize the symptomatic state.

Echocardiographic assessment of left atrial ejection force and kinetic energy in chronic heart failure

BACKGROUND

There is limited information regarding left atrial (LA) systolic adaptation to chronic heart failure (HF) in humans. Therefore, the aim of our study was to determine the LA ejection force (LAEF) and kinetic energy in patients with HF.

METHODS AND RESULTS

58 HF patients (63.8% in NYHA II) and 48 controls were studied. LA volumes were echocardiographically determined using the biplane area-length method. LA systolic function was assessed with the: (a) active emptying volume (ACTEV) and fraction (ACTEF), (b) ejection force (kdynes/m2), calculated with Manning's method [LAEF = 0.5 * rho * mitral orifice area * A2; rho: blood density, Alpha: late transmitral flow velocity] and a modification incorporating parameters of LA function [LAEFm = 0.5 * rho * LA volume at onset of atrial systole * ACTEF * A2/VTl A], and (c) kinetic energy [LA-ke (kdynes.cm/m2) = 0.5 * rho * ACTEV * A2]. LA maximal volume and ACTEV were lower (42.9 +/- 14.4 vs. 59.7 +/- 14.7 cm3, P < 0.0001; 10.9 +/- 3.3 vs. 13 +/- 3.3 cm3, P = 0.0001, respectively), whereas ACTEF (%) was higher (36.3 +/- 7 vs. 29.3 +/- 7.6 cm3, P < 0.0001) in controls than HF. LAEF, LAEFm, and LA-ke were lower in controls than HF (7.68 +/- 5.1 vs. 10.16 +/- 3.7 kdynes/m2, P = 0.006; 3.63 +/- 2.05 vs. 5.02 +/- 1.74 kdynes/m2, P = 0.0004; 2.41 +/- 1.91 vs. 3.99 +/- 2.1 kdynes.cm/m2, P < 0.0004, respectively).

CONCLUSION

Despite the decreased LA systolic shortening, overall LA systolic performance is augmented in chronic HF due to LA dilation.

Left Atrial Remodeling in Acute Anterior Myocardial Infarction

BACKGROUND

Our goal in this study was to examine the changes in the left atrial functions over a period of 3 months by using left atrial volume measurements in patients with anterior myocardial infarction (MI).

METHODS AND RESULTS

Seventy-three patients with anterior MI who consulted our hospital in the first 12 hours starting from the onset of the chest pain and who exhibited ST elevation were enrolled in the study. The left atrial functions of the patients were evaluated by transthoracic echocardiography for a total number of four times; first at the time of the visit to the hospital, then in the first week, and then in the first and third months. Eight (10.95%) of the 73 patients included in the study died during the follow-up. The remaining 65 patients completed the 3-month study period. Of these 65 patients, primary percutaneous transluminal coronary angioplasty (PTCA) was performed for 24 (36.9%) patients and thrombolytic therapy was given to 13 (20%), whereas 28 (43.1%) patients were given only medical treatment. Left atrium (LA) maximum transverse diameter, LA maximum, minimum, and presystolic volume, LA active emptying volume and fraction were found to increase significantly in comparison to baseline detected for this parameter in the first and third months (P < 0.001). However, LA passive emptying volume and fraction was found to decrease significantly in comparison to baseline detected for this parameter in the first and third months (P < 0.001).

CONCLUSIONS

An increase in the diameter, volume, and dimensions of LA during atrial remodeling was detected. LA passive emptying fraction was found to decrease, whereas atrial active emptying function was found to increase to compensate for this change.

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.

Age-related changes in hemodynamics affecting valve performance

Degenerative processes result in changes in both the aortic and mitral valves. For example, degenerative changes may lead to significant aortic stenosis or myxomatous mitral valves. Flows through each valve are determined not only by the properties of the valve itself, but also by the properties of proximal and distal chambers, which also undergo changes with age and diseases associated with the elderly, such as hypertension and coronary artery disease. Assessment of valvular performance should consider the effects of atrial-ventricular coupling (for the mitral valve) or ventricular-arterial coupling (for the aortic valve). Design of therapy or intervention should accordingly consider effects on the system as a whole.

Effect of beta-blocker therapy on left atrial function in patients with heart failure: comparison of metoprolol succinate with carvedilol

OBJECTIVE

We aimed to compare the effects of carvedilol and metoprolol succinate on left atrial (LA) function in patients with chronic heart failure.

METHODS

Thirty three patients (6 females, 27 males) who had not received beta blocker treatment previously and whose left ventricular ejection fraction was below 40% were included in this study. LA volumes were measured echocardiographically just before the time of mitral valve opening (V (max)), onset of atrial systole (p-wave at the electrocardiography = V (p)) and mitral valve closure (V (min)) according to the biplane area length method at baseline and in the 3rd month after the administration of beta blockers. NT-proBNP level was measured at the beginning and in the third month of beta blocker treatment. The first group was given carvedilol 6.25 mg/day, the second group was given 12.5 mg/day metoprolol succinate and it was increased to the tolerable maximal dose.

RESULTS

LA diameter and LA V (max), V (p), V (min) decreased significantly both in carvedilol group and metoprolol group after beta blocker theraphy (P < 0.01, : P < 0.01, : P < 0.05, : P < 0.05: for metoprolol, P < 0.001, P < 0.01, P < 0.01, P < 0.01 for carvedilol). But it was increased in conduit volume (P < 0.05 for two groups). LA-passive emptying fraction, LA-active emptying fraction and reservoir fraction were no significant differences both in carvedilol group and metoprolol group after beta blocker theraphy. NT-proBNP levels were found to decrease significantly in both groups after beta blocker treatment (P < 0.001).:

CONCLUSION

Our findings indicate that beta blocker treatment leads to a decrease in LA diameters and volumes, and metoprolol succinate and carvedilol had similar effects on this decrease.

Left Atrial Size

Left atrial (LA) enlargement has been proposed as a barometer of diastolic burden and a predictor of common cardiovascular outcomes such as atrial fibrillation, stroke, congestive heart failure, and cardiovascular death. It has been shown that advancing age alone does not independently contribute to LA enlargement, and the impact of gender on LA volume can largely be accounted for by the differences in body surface area between men and women. Therefore, enlargement of the left atrium reflects remodeling associated with pathophysiologic processes. In this review, we discuss the normal size and phasic function of the left atrium. Further, we outline the clinically important aspects and pitfalls of evaluating LA size, and the methods for assessing LA function using echocardiography. Finally, we review the determinants of LA size and remodeling, and we describe the evidence regarding the prognostic value of LA size. The use of LA volume for risk stratification is an evolving science. More data are required with respect to the natural history of LA remodeling in disease, the degree of LA modifiability with therapy, and whether regression of LA size translates into improved cardiovascular outcomes.

Strain rate imaging for noninvasive functional quantification of the left atrium: comparative studies in controls and patients with atrial fibrillation

Strain rate (SR) imaging enables quantitative measurement of left ventricular (LV) function independent of cardiac translation. However, whether SR imaging is applicable for detection of left atrial (LA) dysfunction remains unknown. The purpose of this study was to assess the feasibility of measuring LA function by SR imaging, focusing on the effects of aging and LA dilatation during atrial fibrillation (AF). Echocardiographic evaluation including SR imaging was performed in 50 controls (29 males and 21 females; mean age, 41 +/- 14 years) and in 27 patients with AF (15 males and 12 females; mean age, 62 +/- 12 years; 8 with persistent AF and 19 with paroxysmal AF) from 3 apical views and analyzed off-line. Peak SR was measured at each LA segment (septum, lateral, posterior, anterior, and inferior), and mean peak systolic SR (SR-LAs), early diastolic SR (SR-LAe), and late diastolic SR (SR-LAa) were calculated by averaging the results for each segment. LA dimension, peak mitral and pulmonary velocities at late diastole, LA fractional shortening, and atrial filling fraction were calculated as parameters of LA function. Normal values for mean SR-LAs, SR-LAe, and SR-LAa were 3.4 +/- 1.0 s -1 , -3.9 +/- 1.7 s -1 , and -3.1 +/- 1.0 s -1 , respectively, and they were successfully measured in more than 95% of the LA segments. In controls, both mean SR-LAs and mean SR-LAe correlated with age, LA dimension, and early to late diastolic mitral flow velocity ratio. Conversely, mean SR-LAa did not show significant correlation with age or parameters of LA function. In AF patients, mean SR-LAs was correlated inversely with age. The mean SR-LAs was significantly lower in persistent AF patients than in age-matched controls (1.7 +/- 0.8 vs 2.9 +/- 0.9 s -1 ; P < .01). Based on our findings, we conclude that noninvasive quantification of LA function using SR imaging enables evaluation of LA dysfunction due to aging and LA dilatation.

B-type natriuretic peptide as a biomarker beyond heart failure: speculations and opportunities

Cardiac secretion of B-type natriuretic peptide (BNP) Increases with the progression of heart failure (HF), and plasma measurement of BNP has emerged recently as a useful, cost-effective biomarker for the diagnosis and prognosis of HF. The diagnostic utility of BNP is complemented by its therapeutic use in decompensated HF. Although clinical use of BNP as a biomarker in HF is Increasing, the specificity of BNP for HF is not robust, suggesting that other mechanisms beyond simple ventricular stretch stimulate BNP release. Several studies have shown that BNP levels Increase in other cardiovascular disease states including ischemia, arrhythmias, fibrosis, cardiac hypertrophy, and coronary endothelial dysfunction. Furthermore, 2 important studies revealed recently that moderate elevations In BNP level, well below the HF range, have prognostic value for future cardiovascular events. Specifically, BNP levels greater than 20 pg/mL were associated with significantly Increased risk of HF and atrial fibrillation. These observations increase speculation that elevated BNP levels represent a final common pathway for many cardiovascular pathologic states and that BNP can be used as a biomarker for non-HF mechanisms, preclinical disease, and other pathologic states of myocardial disease.

Left atrial systolic reserve in idiopathic vs. ischaemic-dilated cardiomyopathy

PURPOSE

There are studies indicating more pronounced left atrial (LA) systolic dysfunction at rest in idiopathic (IDDC) than in ischaemic-dilated cardiomyopathy (ISDC). It was hypothesized that the findings would be similar with regards LA systolic reserve.

METHODS

Twenty-six patients with IDDC, 28 with ISDC and 25 normal controls underwent low-dose dobutamine stress echocardiography (5-10 microg kg(-1) min(-1) IV). Left atrial volumes were echocardiographically determined at rest and during stress at the mitral valve opening (maximal, Vmax), electrocardiographic P wave (onset of atrial systole, Vp) and mitral valve closure (minimal, Vmin) from the apical 4- and 2-chamber views (biplane area-length method). Left atrial systolic function was assessed with the LA-active emptying volume (ACTEV) = Vp-Vmin and fraction (ACTEF) = ACTEV/Vp.

RESULTS

Vmax at rest was similar in IDDC and ISDC and greater than in the controls (54.2 +/- 12 vs. 48.5 +/- 18 vs. 27.1 +/- 6.3 cm(3) m(-2), respectively, P < 0.001) and did not change with stress (53.9 +/- 13.8 vs. 46.9 +/- 16.2 vs. 25.8 +/- 5.9 cm(3) m(-2), P < 0.001). The ACTEV at rest was similar in IDDC and ISDC and greater than in the controls (8.6 +/- 3.5 vs. 9.7 +/- 2.9 vs. 6.1 +/- 2.2 cm(3) m(-2) P < 0.01), whereas during the dobutamine infusion it remained unaltered in IDDC (10.8 +/- 4.6 cm(3) m(-2), P = NS vs. rest) and increased in ISDC (11.8 +/- 3.3 cm(3) m(-2), P < 0.05) and the controls (13.1 +/- 3.2 cm(3) m(-2), P < 0.01). The ACTEF was lower in IDDC than ISDC and the controls at rest (20 +/- 10% vs. 33 +/- 8% vs. 36 +/- 10%, P < 0.01). Dobutamine infusion was associated with no significant increase in ACTEF in IDDC (25 +/- 12%, P = NS vs. rest), and with an increase in this variable in ISDC (39 +/- 10%, P < 0.05) and the controls (49 +/- 12%, P < 0.01).

CONCLUSIONS

Dobutamine infusion is associated with an increase in LA ACTEV and fraction in ISDC and no significant change in these indices in IDDC. These findings indicate a reduced LA systolic reserve in IDDC.

Usefulness of left atrial emptying fraction to predict exercise capacity in patients with normal systolic left ventricular function and without myocardial ischemia

The association of left atrial volume at rest and the left atrial emptying fraction with exercise capacity during stress echocardiography was examined in patients with normal left ventricular function and without ischemia. The left atrial emptying fraction, along with body mass index, was found to be an independent predictor of poor exercise capacity (<5 METs).

Effects of dipper and non-dipper status of essential hypertension on left atrial mechanical functions

AIM

This study was designed in order to investigate the effects of dipper and non-dipper status of hypertension on left atrial mechanical (reservoir, conduit and booster pump) functions with left atrial volume measurements by means of two-dimensional echocardiography in untreated systemic hypertensive patients.

METHOD

A total of 27 untreated dipper hypertensive patients, group I (15 female, 12 male, mean age 57+/-12 years); 23 untreated non-dipper hypertensive patients, group II (12 female, 11 male, mean age: 53+/-18 years); and 25 voluntary healthy individuals, group III (13 female, 12 male, mean age 53+/-10 years) were included into the study. Twenty-four hour blood pressure (BP) measurement was performed by the cuff-oscillometric method to evaluate the nocturnal decrease of BP. The patients whose night time mean blood pressure measurements were found 10% or more lower compared to mean day time measurements were classified as dipper hypertensive patients and the ones with a decrease of less than 10% were classified as non-dipper hypertensive patients. Left atrial (LA) volumes were measured echocardiographically according to biplane area-length method in apical four-chamber and two-chamber views. LA maximal volume (V(max)) was recorded at the onset of mitral opening, LA minimal volume (V(min)) was recorded at the onset of mitral closure and LA presystolic volume (V(p)) was recorded at the beginning of the atrial systole (p wave on ECG). All volume measurements were corrected to body surface area, and following LA emptying functions parameters were calculated: LA passive emptying volume (LAPEV)=V(max)-V(p), LA passive emptying fraction (LAPEF)=LAPEV/V(max), Conduit volume (CV)=left ventricular output volume-(V(max)-V(min)), LA active emptying volume (LAAEV)=V(p)-V(min), LA active emptying fraction (LAAEF)=LAAEV/V(p), LA total emptying volume (LATEV)=V(max)-V(min), LA total emptying fraction (LATEF)=LATEV/V(max).

RESULTS

LA volume indexes, V(max), V(min), and V(p), were significantly increased in the hypertensive subgroups (groups I and II) than in controls (p<0.001, p<0.001, p<0.001, respectively), but no significant difference was found in the V(p) values between group I and group II. V(max) and V(min) were larger in non-dipper hypertensive group than in dipper hypertensive group (p<0.05 and p<0.05, respectively). LAPEV and LAPEF were observed to be significantly reduced in both dipper and non-dipper hypertensives than in control (p<0.001 and p<0.05, respectively), and this difference was more obvious in non-dipper than dipper cases (p<0.001). Conduit volume was significantly lower in hypertensive groups than controls (p<0.05). LA active emptying volume (p<0.001) and LAA active emptying fraction (p<0.001) were significantly greater in hypertensive cases than in controls. Furthermore, LA active emptying volume in non-dipper hypertensive subjects was significantly greater than dipper hypertensive cases (p<0.05). Left atrial total emptying volume and left atrial total emptying fraction in both hypertensive groups were similar to control (p>0.05).

CONCLUSIONS

Atrial reservoir and booster pump functions increase in hypertensive patients, but this result is more prominent in non-dipper hypertensives than in dipper hypertensive patients.

Left atrial systolic function in primary and familial amyloidosis: assessment from left atrial volume change

The severity of left ventricular involvement may differ between primary (PA) and familial amyloidosis (FA). This study examined whether differences in left atrial (LA) systolic function are also present. Twenty-eight patients (18 men, 10 women, aged 59 +/- 12 years) with PA, 17 (11 men, 6 women, aged 40 +/- 11 years) with FA, and 25 normal controls (18 men, 7 women, aged 56 +/- 14 years) underwent transthoracic M-mode, two-dimensional, and Doppler echocardiography. Left atrial volumes were determined at mitral valve (MV) opening (maximal, Vmax), electrocardiographic P wave (onset of atrial systole, Vp), and MV closure (minimal, Vmin) from the apical two-and four-chamber views using the biplane area-length method. Left atrial systolic function was assessed with the LA active emptying volume (ACTEV) = Vp-Vmin and fraction (ACTEF) = ACTEV/Vp. The E/A ratio was increased (1.34 +/- 0.93 vs. 0.89 +/- 0.3), whereas deceleration time was decreased (168.1 +/- 33.7 vs. 196.2 +/- 34.2 ms) in PA compared with FA (p<0.05). Vmax and Vp were similar in PA and FA and greater than in the controls (46.6 +/- 14 vs. 40 +/- 11.4 vs. 27.1 +/- 6.3 cm3/m2, p<0.01, and 33.4 +/- 11.6 vs. 29.7 +/- 10.8 vs. 16.8 +/- 3.8 cm3/m2, p<0.01, respectively). The ACTEV was lower in PA and in the controls than in FA (6.7 +/- 2 vs. 6.2 +/- 2.2 vs. 8.5 +/- 3.3, respectively, p<0.05). The ACTEF was lower in PA than in FA and both were lower than those in the controls (20 +/- 5% vs. 28 +/- 7% vs. 36 +/- 11%, respectively, p<0.01). Despite a similar increase in LA volume, LA systolic dysfunction is more pronounced in PA than in FA. This is most likely due to the restrictive left ventricular physiology possibly associated with depressed LA contractility in the former.

MRI and echocardiographic assessment of the diastolic dysfunction of normal aging: altered LV pressure decline or load?

Changes in diastolic indexes during normal aging, including reduced early filling velocity ( E), lengthened E deceleration time (DT), augmented late filling ( A), and prolonged isovolumic relaxation time (IVRT), have been attributed to slower left ventricular (LV) pressure (LVP) decay. Indeed, this constellation of findings is often referred to as the “abnormal relaxation” pattern. However, LV filling is determined by the atrioventricular pressure gradient, which depends on both LVP decline and left atrial (LA) pressure (LAP). To assess the relative influence of LVP decline and LAP, we studied 122 normal subjects aged 21–92 yr by Doppler echocardiography and MRI. LVP decline was assessed by color M-mode ( Vp) and the LV untwisting rate. Early diastolic LAP was evaluated using pulmonary vein flow systolic fraction, pulmonary vein flow diastolic DT, color M-mode ( E/ Vp), and tissue Doppler ( E/ Em). Linear regression showed the expected reduction of E, increase in A, and prolongation of IVRT and DT with advancing age. There was no relation of age to parameters reflecting the rate of LVP decline. However, older age was associated with reduced E/ Vp ( P = 0.008) and increased pulmonary vein systolic fraction ( P < 0.001), pulmonary vein DT ( P = 0.0026), and E/ Em ( P < 0.0001), all suggesting reduced early LAP. Therefore, reduced early filling in older adults may be more closely related to a reduced early diastolic LAP than to slower LVP decline. This effect also explains the prolonged IVRT. We postulate that changes in LA active or passive properties may contribute to development of the abnormal relaxation pattern during the aging process.

Comparison of left atrial volume and function after linear ablation and after cardioversion for chronic atrial fibrillation

Several techniques for treatment of atrial fibrillation (AF) have been developed, including the direct placement of radiofrequency for lesions at open heart surgery. Detailed evaluation of left atrial (LA) function has not been performed after these procedures and has not been compared in patients with chronic AF. We compared the atrial function of patients with sustained sinus rhythm (SR) after linear ablation with a group who underwent direct-current cardioversion and a group of normal controls to investigate the measurable deleterious effects, if any, on atrial function after the surgical procedure. Twenty-one consecutive patients who had maintained SR for >6 months after a linear radiofrequency ablation (LRFA) procedure were studied. As control subjects, we examined 33 patients with chronic AF successfully restored to SR by cardioversion who maintained SR for >6 months and 42 age-matched normal subjects. LA function was decreased in both the LRFA and cardioverted AF groups compared with normal controls. The parameters of LA function, atrial fraction, LA ejection fraction, and the A' velocity were lowest in the LRFA group, intermediate in the cardioverted AF group, and highest in the normal controls (LA function: 15.8 +/- 10%, 26 +/- 10%, 33 +/- 7%; p = 0.0001; LA ejection fraction: 31 +13%, 41 +/- 12%, 51 +/- 9%; p = 0.0001; A' velocity: 4.2 +/- 1.4, 7.6 +/- 2.2, 9.5 +/- 1.9 cm/s; p = 0.0001). LA volumes were increased in the LRFA and cardioverted AF groups compared with normals (62.8 +/- 22 vs 70.6 +/- 17 vs 38.7 +/- 9.8 ml; p = 0.0001). Thus, although LA function is restored and maintained after LRFA has been performed during open heart surgery, LRFA use is associated with a measurable decrease in LA function over and above that found after conventional cardioversion.

Risks for atrial fibrillation and congestive heart failure in patients >/=65 years of age with abnormal left ventricular diastolic relaxation

We sought to determine the risk for the first episodes of atrial fibrillation (AF) and congestive heart failure (CHF) in a cohort of patients aged >/=65 years who had abnormal left ventricular (LV) diastolic relaxation. Records were reviewed for all residents of Olmsted County, Minnesota, who had >/=1 transthoracic echocardiogram performed at the Mayo Clinic between 1990 and 1998, and who were in sinus rhythm and did not have a history of AF, CHF, valvular or congenital heart disease, permanent pacemaker, or stroke. Of 994 patients who qualified and had LV diastolic function assessment, abnormal LV relaxation was identified in 569 (57%), 105 of whom (18%) developed a first episode of AF or CHF over a mean follow-up of 4.0 +/- 2.7 years. Age (p <0.0001), history of myocardial infarction (p <0.0001), history of diabetes mellitus (p = 0.041), electrocardiographic LV hypertrophy (p = 0.0223), and indexed left atrial (LA) volume (p = 0.0003) were independent predictors. A stepwise increase in age-adjusted risk was evident when stratified by tertiles of indexed LA volume (<27 ml/m(2); 27 to 37 ml/m(2); >37 ml/m(2)). Compared with patients with normal LV diastolic function (n = 148, 15%), the risks for first episodes of AF or CHF were not different in those with abnormal diastolic relaxation if LA volume was <27 ml/m(2) (p = 0.303). In conclusion, these data suggest the presence of a wide spectrum of risks for AF or CHF in the elderly who have abnormal LV diastolic relaxation, with the highest risks evident in those with the largest left atria. When LA volume was <27 ml/m(2), however, the risks for these events were not different from those with normal LV diastolic function.

Left atrial and left ventricular function in healthy children and young adults assessed by three dimensional echocardiography

OBJECTIVE

To establish normal values of left atrial and left ventricular volumes and function in children and young adults using three dimensional echocardiography (3DE).

METHODS

169 healthy subjects aged 2 to 27 years were studied by digitised 3DE. 3DE was achieved using rotational acquisition of planes at 18 degrees intervals from the parasternal view for the left atrium and from the transthoracic apical view for the left ventricle with ECG gating and without respiratory gating. Left atrial and left ventricular volumes could be calculated throughout the heart cycle, and the respective time-volume curves were reconstructed in each subject.

RESULTS

For the analysis the subjects were divided into five groups according to body surface area: 0.5-0.75 m2, 0.75-1.0 m2, 1.0-1.25 m2, 1.25-1.5 m2, and over 1.5 m2. Mean (SD) left atrial maximum volume/body surface area was 19.6 (3.5), 21.7 (3.7), 22.0 (4.7), 24.5 (4.8), and 27.4 (6.4) ml/m2; left ventricular maximum volume/body surface area was 50.1 (8.8), 54.9 (10.1), 56.4 (9.9), 58.7 (11.0), and 64.4 (10.3) ml/m2. Left atrial active emptying increased from 19% to 35% with age (r = 0.34, p < 0.001) and with decreasing heart rate (r = -0.28, p < 0.001).

CONCLUSIONS

Transthoracic 3DE is well suited for studying the phasic changes in left atrial and left ventricular volumes in young children as well as in adults. The data obtained from 169 healthy subjects will serve as a reference for further studies in patients with various cardiac abnormalities.