Early Left Atrial Mechanics and Volume Abnormalities in Subjects with Prehypertension: A Real Time Three-Dimensional Echocardiography Study

Pathophysiology of Hypertensive Heart Disease: Beyond Left Ventricular Hypertrophy

PURPOSE OF REVIEW

Given that the life expectancy and the burden of hypertension are projected to increase over the next decade, hypertensive heart disease (HHD) may be expected to play an even more central role in the pathophysiology of cardiovascular disease (CVD). A broader understanding of the features and underlying mechanisms that constitute HHD therefore is of paramount importance.

RECENT FINDINGS

HHD is a condition that arises as a result of elevated blood pressure and constitutes a key underlying mechanism for cardiovascular morbidity and mortality. Historically, studies investigating HHD have primarily focused on left ventricular (LV) hypertrophy (LVH), but it is increasingly apparent that HHD encompasses a range of target-organ damage beyond LVH, including other cardiovascular structural and functional adaptations that may occur separately or concomitantly. HHD is characterized by micro- and macroscopic myocardial alterations, structural phenotypic adaptations, and functional changes that include cardiac fibrosis, and the remodeling of the atria and ventricles and the arterial system. In this review, we summarize the structural and functional alterations in the cardiac and vascular system that constitute HHD and underscore their underlying pathophysiology.

Evaluation of left atrial volume and function in patients with coronary slow flow phenomenon using real-time three-dimensional echocardiography

This study aimed to evaluate the left atrial (LA) volume and phasic functions using real-time three-dimensional echocardiography (RT3DE) in coronary slow flow phenomenon (CSFP) patients with preserved left ventricular ejection fraction (LVEF). 56 patients with CSFP (36 males, 20 females) and 48 controls with normal coronary flow (27 males, 21 females) were prospectively enrolled. Comprehensive transthoracic echocardiographic examination and RT3DE for the assessment of LA dynamics were performed in all participants. LA maximum, minimum, and pre-atrial contraction volumes (LAV-max, LAV-min, and LAV-preA) were obtained for every subject. Conventional echocardiographic parameters, except for isovolumetric relaxation time and transmitral deceleration time, did not differ in two groups. RT3DE demonstrated higher LAV-max, LAV-min, LAV-preA, indexed LAV-max (LAVi-max), LA total emptying volume, and LA active emptying volume and fraction for CSFP patients compared with controls (all P < 0.05). In addition, LA total emptying fraction and LA passive emptying fraction were found to be lower in CSFP patients than in controls (all P < 0.05). Moreover, there were positive correlations between mean thrombolysis in myocardial infarction frame count values and LAV-max, LAV-min, LAV-preA, LAVi-max, and LA total and active emptying volumes. CSFP was associated with enlarged LA volumes, impaired LA reservoir and conduit function and enhanced contractile function. Evaluation of LA dynamics using RT3DE could facilitate recognition of subtle myocardial alterations related with CSFP.

Evaluation of left atrial volume and functions by real time three-dimensional echocardiography in patients with subclinical hypothyroidism before and after levothyroxine therapy

BACKGROUND/AIMS

The cardiovascular system is one of the major targets of thyroid hormones. Subclinical hypothyroidism (SCH) is a common disease that can represent "early" thyroid failure. Our aim was to evaluate left atrial (LA) volume and functions in patients with SCH using real time three-dimensional echocardiography (RT3DE) and also to investigate changes in LA parameters after the levothyroxine treatment.

METHODS

In total, 44 patients with SCH and 40 age- and gender-matched controls were studied. Assessments included history, physical examination and echocardiography. All patients with SCH were followed up with replacement therapy until the euthyroid status was achieved.

RESULTS

In patients with SCH, LA total emptying volume, passive emptying volume, and passive ejection fraction were significantly reduced while LA minimal volume, active emptying volume, and active emptying fraction were significantly increased than in control group. Following the levothyroxine treatment, LA volume and function parameters were observed to be significantly improved. A negative correlation between the change of thyroid stimulating hormone (TSH) and change of LA active emptying volume and a positive correlation between the change of TSH level and change of LA passive emptying volume were found.

CONCLUSION

It was shown that volume and functions of LA were impaired in patients with SCH. However, impaired parameters were improved after the levothyroxine treatment. These findings may be indicative of subclinical heart involvement that could lead to functional and structural changes in patients with SCH.

Association of central blood pressure with left atrial structural and functional abnormalities in hypertensive patients: Implications for atrial fibrillation prevention

Aims

Functional and structural abnormalities of the left atrium have been demonstrated to be clinically and prognostically significant in a range of cardiovascular disorders, increasing the risk of atrial fibrillation. Among the potential contributors to these aberrations, central arterial factors remain insufficiently defined. Accordingly, we sought to investigate the determinants of left atrium abnormalities in hypertension, with special focus on central haemodynamics.

Methods

In this retrospective, cross-sectional study, 263 patients (age 63.8 ± 8.0 years) with uncomplicated hypertension underwent echocardiography including left atrium strain (LAS) and volume analysis, and central haemodynamics assessment using radial tonometry.

Results

Patients were grouped depending on LAS and left atrium volume index (LAVI), using externally validated cutpoints (34.1% for LAS and 34 ml/m2for LAVI). The subset with lower LAS ( n = 124) demonstrated higher central (cPP) and brachial pulse pressure (bPP), ventricular- arterial coupling, left ventricular mass index (LVMI) and LAVI, and lower global left ventricular longitudinal strain and early diastolic tissue velocity (e′). Patients with higher LAVI ( n = 119) presented higher systolic blood pressure, cPP, bPP, central augmentation pressure, LVMI and E/e′ ratio and lower LAS. In multivariable analysis, cPP was independently associated with both LAS ( β = –0.22; p = 0.002) and LAVI ( β = 0.21; p = 0.003). No independent associations with left atrium parameters were shown for bPP.

Conclusion

Higher cPP is detrimentally associated with left atrium structural and functional characteristics, thus providing a possible pathophysiological link with the development of substrate for atrial fibrillation. Prophylaxis of atrial fibrillation might be another argument for consideration in the treatment strategy in hypertension targeted measures addressing central blood pressure.

Assessment of left atrial volume and function by real time three-dimensional echocardiography in obese patients

OBJECTIVE

To evaluate left atrial (LA) volume and functions in obese subjects using real time three-dimensional echocardiography (RT3DE) and also the relationship between LA mechanical functions and N-terminal pro-atrial natriuretic peptide (NT-proANP).

METHODS

This study included 40 obese (26 females and 14 males, mean age 51.9 years) and 40 normal weight subjects (23 females and 16 males, mean age 53.5 years) with normal coronary angiograms. All the study participants underwent RT3DE to assess LA volume and mechanical function. Plasma NT-proANP was determined by ELISA method.

RESULTS

There was no significant difference between groups in left ventricular (LV) diameters and ejection fraction, which reflect LV systolic function. However, transmitral deceleration time, isovolumetric relaxation time, and peak late diastolic tissue Doppler velocity values, which reflect LV diastolic function, were found to be significantly higher in obese subjects when compared with controls. LA maximum volume (LAVmax), LAVmax index (LAVI), LA minimal volume (LAVmin), before atrial contraction volume (LAVpreA), LA active emptying volume, LA total emptying volume, and LA active emptying fraction, which reflect LA reservoir and pump functions, were also higher in obese subjects when compared with controls. LA passive emptying fraction was significantly lower in obese subjects than in controls. NT-proANP levels were similar between groups. There were positive correlations between NT-proANP level and LAVI, LAVmax, LAVmin, LAVpreA, and LA total and active emptying volumes.

CONCLUSIONS

Left atrial mechanical functions and volumes are impaired in obese subjects. These findings may be regarded as early markers of subclinical cardiac failure in obese subjects who have not yet exhibited any clinical evidence of cardiovascular disease.

Comparison of left atrial volume and function in non-dipper versus dipper hypertensives: A real-time three-dimensional echocardiography study

OBJECTIVE

Non-dipper hypertension is associated with an increased cardiovascular morbidity and mortality. Besides this, the left atrial (LA) size and functions are accepted to be prognostic factors in various cardiovascular diseases. In this study, we aimed to evaluate the effect of nondipper hypertension on LA volume and functions using real-time three-dimensional echocardiography (RT3-DE).

METHODS

Forty dipper and 52 non-dipper hypertensives enrolled in this prospective cross-sectional study. Patients with any comorbidities that have a potential for causing structural cardiac alterations were excluded. Two-dimensional echocardiography (2-DE) and RT3-DE were performed to assess LA volumes and functions. The statistical tests used in this study were Shapiro-Wilk's test, Student's t-test, Mann-Whitney U test, chi-square test, Spearman's test, and Pearson's correlation test.

RESULTS

LA minimal volume, LA volume before LA contraction, and LA total systolic volume were higher in non-dipper hypertensives than in dipper hypertensives (p<0.001, p=0.003, and p=0.03, respectively). Only, the 2-DE measurements of interventricular septal thickness and E/Em ratio were higher in non-dipper hypertensives (p=0.001 and p=0.03, respectively). There was a moderate correlation between LA minimal volume and LA volume before LA contraction with E/Em (r=0.31, p=0.007 and r=0.32, p=0.005, respectively).

CONCLUSION

Although LA volume and passive LA systolic functions measured by RT3-DE are significantly increased in non-dipper hypertensives, the alterations in active LA systolic functions are not prominent. RT-3DE may be used to define LA volume and function alterations in conditions that have capabilities of adverse cardiac remodeling such as systemic hypertension.