Midwall mechanics in physiologic and hypertensive concentric hypertrophy

Maternal Cardiac Adaptations to a Physical Exercise Program during Pregnancy

INTRODUCTION

Scarce evidence exists regarding the effects of regular pregnancy exercise on maternal cardiovascular health. We aimed to study, using a randomized controlled trial design, the effects of pregnancy exercise on echocardiographic indicators of hemodynamics, cardiac remodeling, left ventricular (LV) function, and cardiovascular disease (CVD) risk factors.

METHODS

Two hundred forty-one healthy pregnant women were assigned to a control (standard care) or intervention (exercise) group (initial n = 121/120). The intervention (weeks 9-11 to 38-39) included three supervised sessions per week (55-60 min, with light-moderate intensity aerobic and strength exercises).

RESULTS

The main findings were as follows: (i) the proportion of women with excessive weight gain at end pregnancy was lower in the exercise group compared with controls (18% vs 40%, P = 0.005), and (ii) there was a tendency toward lower prevalence of depression at end pregnancy in the former (P = 0.029, threshold P value set at 0.013). No significant exercise training effect was essentially found for echocardiographic variables, CVD risk factors, type/duration of labor, or newborn's outcomes (weight, height, head circumference, Apgar scores, and umbilical cord pH).

CONCLUSIONS

Light-moderate intensity supervised exercise is safe for healthy pregnant women and does not impose an additional cardiac overload beyond gestation or affect the main pregnancy outcomes. Such intervention might help decrease, at least partly, the risk of two CVD-associated conditions, excessive weight gain and depression.

Recommendations on the Use of Echocardiography in Adult Hypertension: A Report from the European Association of Cardiovascular Imaging (EACVI) and the American Society of Echocardiography (ASE)

Hypertension remains a major contributor to the global burden of disease. The measurement of blood pressure continues to have pitfalls related to both physiological aspects and acute variation. As the left ventricle (LV) remains one of the main target organs of hypertension, and echocardiographic measures of structure and function carry prognostic information in this setting, the development of a consensus position on the use of echocardiography in this setting is important. Recent developments in the assessment of LV hypertrophy and LV systolic and diastolic function have prompted the preparation of this document. The focus of this work is on the cardiovascular responses to hypertension rather than the diagnosis of secondary hypertension. Sections address the pathophysiology of the cardiac and vascular responses to hypertension, measurement of LV mass, geometry, and function, as well as effects of treatment.

Obesity and hypertensive heart disease: focus on body composition and sex differences

There is evidence that hypertension is frequently associated with overweight/obesity even in kids and adolescents. Either conditions influence development of left ventricular (LV) hypertrophy (LVH), through different biological and hemodynamic mechanisms: obesity is conventionally thought to elicit a coherent growth of LV chamber dimensions and myocardial wall thickness (eccentric LV geometry), whereas a more accentuated increase in wall-thickness (concentric LV geometry) is attributed to hypertension. While during youth these differences are visible, proportion of LV concentric geometry, the most harmful LV geometric pattern, sharply raises in obese individuals during middle age, and becomes the most frequent geometric patterns among obese-hypertensive individuals. Two conditions with elevated hemodynamic impact, severe obstructive sleep apnea and masked hypertension contribute to the development of such a geometric pattern, but non-hemodynamic factors, and specifically body composition, also influence prevalence of concentric LV geometry. Contrasting a general belief, it has been observed that adipose mass strongly influences LV mass, particularly in women, especially when fat-free mass is relatively deficient. Thus, though blood pressure control is mandatory for prevention and reduction of LVH in obese hypertensive patients, without reduction of visceral adiposity regression of LVH is difficult. Future researches should be addressed on (1) assessing whether LVH resulting from alteration of body composition carries the same prognosis as pressure overload LVH; (2) defining tissue characterization of the hypertrophic heart in obese-hypertensive patients; (3) evaluating whether assessment of hemodynamic loading conditions and biological markers can help defining management of the association of obesity with hypertension.

Endurance and Strength Athlete's Heart: Analysis of Myocardial Deformation by Speckle Tracking Echocardiography

Background

Intensive training induces two morphological myocardial typologies of athlete's heart. Endurance training (ET) induces eccentric remodeling, bradycardia and better diastolic filling. Strength training (ST) determines concentric chamber remodelling maintaining a normal heart rate (HR). Aim of the study was to compare ET and ST athletes' heart using speckle tracking echocardiography (STE).

Methods

33 professional ET, 36 ST athletes, and 17 healthy controls (CT) were enrolled. All subjects underwent standard transthoracic echocardiography at rest and STE.

Results

In ET group, HR was lower than ST group and CT group (p < 0.001; p < 0.01). ET group had higher E/A ratio than ST group and CT group (p < 0.01; p < 0.001). The left ventricular apical circumferential strain in ET group was lower than ST group and CT group (-21.6 ± 4.1% vs. -26.8 ± 7.7%, p < 0.05; vs. -27.8 ± 5.6%, p < 0.01). ET group had lower left ventricular twist (LVT) and untwisting (UTW) than ST group (6.2 ± 0.1° vs. 12.0 ± 0.1°, p < 0.01; -67.3 ± 22.9°/s vs. -122.5 ± 52.8°/s, p < 0.01) and CT group (10.0 ± 0.1°, p < 0.01; -103.3 ± 29.3°/s, p < 0.01). The univariate analysis showed significant correlation between E/A ratio and HR (r = -0.54; p < 0.001), LVT (r = -0.45; p < 0.01), UTW (r = 0.24; p < 0.05). At the multivariate analysis only HR was confirmed as independent predictor of diastolic function in all groups (Beta -0.52; p < 0.001).

Conclusion

In ET there was a better global systolic and diastolic functional reserve at rest observed with strain analysis and it maybe depended on autonomic modulation.

Prognostic value of depressed midwall systolic function in cardiac light-chain amyloidosis

BACKGROUND

Cardiac amyloidosis represents an archetypal form of restrictive heart disease, characterized by profound diastolic dysfunction. As ejection fraction is preserved until the late stage of the disease, the majority of patients do fulfill the definition of diastolic heart failure, that is, heart failure with preserved ejection fraction (HFpEF). In another clinical model of HFpEF, that is, pressure-overload hypertrophy, depressed midwall fractional shortening (mFS) has been shown to be a powerful prognostic factor.

OBJECTIVE AND METHODS

To assess the potential prognostic role of mFS in cardiac light-chain amyloidosis with preserved ejection fraction, we enrolled 221 consecutive untreated patients, in whom a first diagnosis of cardiac light-chain amyloidosis was concluded between 2008 and 2010. HFpEF was present in 181 patients. Patients in whom cardiac involvement was excluded served as controls (n = 121). Prognosis was assessed after a median follow-up of 561 days.

RESULTS

When compared with light-chain amyloidosis patients without myocardial involvement, cardiac light-chain amyloidosis was characterized by increased wall thickness (P <0.001), reduced end-diastolic left ventricular volumes (P <0.001), and diastolic dysfunction (P <0.001). In patients with preserved ejection fraction, mFS was markedly depressed [10.6% (8.7-13.5) vs. 17.8% (15.9-19.5) P <0.001]. At multivariable analysis, mFS, troponin I, and NT-pro-brain natriuretic peptide were the only significant prognostic determinants (P <0.001), whereas other indices of diastolic (E/E' ratio, transmitral and pulmonary vein flow velocities) and systolic function (tissue Doppler systolic indices, ejection fraction), or the presence/absence of congestive heart failure did not enter the model.

CONCLUSION

In cardiac light-chain amyloidosis with normal ejection fraction, depressed circumferential mFS, a marker of myocardial contractile dysfunction, is a powerful predictor of survival.

Left ventricular twisting modifications in patients with left ventricular concentric hypertrophy at increasing after-load conditions

AIMS

Left ventricular hypertrophy (LVH) develops as a result of several clinical conditions, such as intensive training, hypertension, aortic valve stenosis. Aim of this study was to analyze the left ventricular twist (LVT) modifications in LVH patients with increasing after-load conditions.

METHODS

A total of 131 patients were enrolled: 17 healthy sedentary people (Hg), without concentric LVH; 45 water polo players (ATg); 22 patients with hypertensive cardiopathy (HPg); 47 patients with different degrees of aortic stenosis (ASg); all patients had concentric LVH, ejection fraction (EF) >54%, and were age-matched. The left ventricular end-systolic wall stress (LV-ESWS) was used as index of after-load.

RESULTS

Left ventricular twist value showed a progressive increase from ATg to ASg, according to increasing after-load. Longitudinal left ventricular function by tissue Doppler imaging (TDI) and speckle tracking echocardiography (STE) was reduced in HPg and ASg. There was a negative correlation between LVT and longitudinal systolic function at TDI and STE (r = -0.4; P < 0.001; -0.23; P < 0.05). E/A ratio was lower in HPg and ASg than ATg and Hg. LVT was linearly related to LV-ESWS (r = 0.36; P < 0.01), E/A ratio (r = -0.59; P < 0.001), E/E' ratio (r = 0.43; P < 0.001), age (r = 0.5; P < 0.001), relative wall thickness (RWT) (r = 0.38; P < 0.01), heart rate (HR) (r = 0.3; P < 0.05), maximum (G. max), and mean transvalvular gradient (G. mean) in ASg (r = 0.37; P < 0.01, r = 0.4; P < 0.01). RWT, E/A ratio, and HR were independent predictor of LVT (β = 0.23; P = 0.007; -0.44; P = 0.001; 0.17; P = 0.049). Only in ASg, G. mean was independent predictor of LVT (β = 0.44; P = 0.01).

CONCLUSION

Left ventricular twist showed a linear trend at increasing after-load values to compensate the reduction in systolic longitudinal function in pathological LVH patients.

Increased short-term blood pressure variability is associated with early left ventricular systolic dysfunction in newly diagnosed untreated hypertensive patients

BACKGROUND AND AIM

Twenty-four-hour blood pressure (BP) variability, by ambulatory BP monitoring (ABPM), has been related to left ventricular hypertrophy, independent of mean BP values. We tested the hypothesis that short-term BP variability (BPV) is also related to subclinical left ventricular systolic dysfunction.

METHODS

We assessed 24-h SBP and DBP variabilities, quantified as standard deviation (SD) of daytime (awake) BP values and as weighted SD of 24-h BP (24-h-weighted BPV), in 309 recently (<6 months) diagnosed, prospectively recruited, and untreated hypertensive patients. Patients were included only if with normal (≥55%) left ventricular ejection fraction (LVEF). Left ventricular systolic function was assessed by echocardiography measuring midwall fractional shortening (MFS), circumferential end-systolic stress (cESS), MFS/cESS, peak systolic wall stress, left ventricular fractional shortening (LVFS), and LVEF.

RESULTS

At multivariate analysis, awake and 24-h-weighted SBP variabilities (directly, P = 0.038 and P = 0.002, respectively) as well as relative wall thickness (RWT) (inversely, P = 0.001) were significantly related to cESS. Awake and 24-h SBP average values (inversely, P = 0.011 and P = 0.002, respectively), awake and 24-h-weighted SBP variabilities (inversely, P = 0.017 and P = 0.024, respectively), and RWT (directly, P = 0.001) were all significantly related to MFS/cESS. Finally, awake and 24-h average SBP (directly, P = 0.01 for both), awake and 24-h-weighted SBP variability (directly, P = 0.001 and P = 0.032, respectively), and RWT (inversely, P = 0.001) were all significantly and independently related to peak systolic wall stress.

CONCLUSION

In newly diagnosed never-treated hypertensive patients, in the absence of LVEF changes and independent of left ventricular mass index, higher awake, or 24-h-weighted short-term SBP variabilities are associated with early depressed left ventricular systolic function.

Evaluation of left anterior descending coronary artery stenosis severity from myocardial end-diastolic wall stress estimated by tissue-Doppler imaging

PURPOSE

To identify patients with significant coronary artery disease by the noninvasive quantification of myocardial wall stress in diastole.

METHODS

We studied 60 male subjects in sinus rhythm with significant (n = 30) or moderate (n = 30) proximal left anterior descending coronary artery stenosis, and 30 healthy subjects (control group). The average end-diastolic wall stress was estimated at left ventricle anterior and interventricular septum wall segments from regional wall thickness, meridional and circumferential regional radii of curvature, and noninvasively estimated left ventricular end-diastolic pressure.

RESULTS

There were significant differences in left ventricular end-diastolic pressure between patients and controls (p < 0.05). End-diastolic myocardial wall stress was significantly different between patients with significant and moderate coronary stenosis and healthy subjects in all anterior and septal wall segments (p < 0.05) except for the anterior wall at mid level. The receiver-operating characteristic curves showed that septum apex wall stress has the highest discriminatory power for predicting significant stenosis versus healthy coronary artery with 83% area under the curve.

CONCLUSIONS

Estimated end-diastolic myocardial wall stress may help in evaluating regional myocardial dysfunction due to coronary artery disease.

Differential expression of TRPC channels in the left ventricle of spontaneously hypertensive rats

This study was designed to identify the differential expression of the canonical transient receptor potential (TRPC) channels in the left ventricle of spontaneously hypertensive rats (SHR). Echocardiography studies were performed to compare the left ventricular function in SHR vs. Wistar-Kyoto rats (WKY), and the mRNA level of the TRPC channels was determined by quantitative real-time RT-PCR (qRT-PCR). Western blots were performed to examine whether the mRNA expression corresponded with the protein expression. Compared with the WKY, the mRNA expression of TRPC4 and TRPC5 was significantly increased in the 10-week-old SHR (P = 0.032 for TRPC4 and P = 0.043 for TRPC5), so did the TRPC4/5 protein content. The midwall fractional shortening (mFS) of SHR was lower than WKY (P = 0.016). Furthermore, increased expression of TRPC4/5 was correlated with both increased blood pressure and decreased mFS. These findings suggest that TRPC4 and 5 seem to be the main subtypes expressed in the heart of the SHR at the beginning period of hypertension. Theses channels may participate in the development of left ventricular systolic dysfunction.

Left ventricular longitudinal systolic dysfunction is an independent marker of cardiovascular risk in patients with hypertension

BACKGROUND

To explore the prognostic value of left ventricular (LV) longitudinal systolic dysfunction in patients with hypertension.

METHODS

In 156 hypertensive subjects, LV longitudinal systolic function was assessed by echocardiographic measurement of M-mode left atrioventricular plane displacement (AVPD) and Tissue Doppler (TD)-derived mitral annulus peak systolic velocity (Sm). Patients were followed for development of the following cardiovascular events: congestive heart failure requiring hospitalization, new-onset angina, nonfatal myocardial infarction, coronary revascularization procedures, transient ischemic attack, nonfatal stroke, and cardiovascular death.

RESULTS

Over a follow-up of 23.3 +/- 5.4 months, 24 patients had 29 events. Both longitudinal systolic indices were predictive of outcome (hazard ratios: AVPD, 0.24, P < 0.001; Sm, 0.22; P < 0.001). AVPD < or = 11.4 mm (75.0% sensitivity and 53.8% specificity) and Sm < or = 8.9 cm/s (79.2% sensitivity and 61.4% specificity) were identified as the best cutoffs for the prediction of cardiovascular events (area under curve: AVPD, 0.66, P < 0.01; Sm, 0.71; P < 0.0001). Compared to conventional indices of circumferential systolic function, AVPD and Sm showed similar overall diagnostic performance, but higher sensitivity and lower specificity. Coexistence of longitudinal and circumferential systolic dysfunction was associated with the worst prognosis (P < 0.0001). Multivariate analysis confirmed an independent association of longitudinal indices with clinical outcome, incremental to circumferential systolic impairment, and other confounding variables.

CONCLUSIONS

Longitudinal systolic dysfunction is an independent marker of cardiovascular risk in hypertensive patients. Despite similarity in predictive accuracy, longitudinal indices are more sensitive but less specific than circumferential indices for the prediction of cardiovascular events in these subjects.

Impact of obesity on left ventricular mass and function in subjects with chronic volume overload

OBJECTIVE

Previous studies evaluated the effect of obesity on left ventricular (LV) mass and systolic function in healthy subjects and in patients with coexistent chronic LV pressure overload due to hypertension, but no data exist regarding subjects with underlying volume overload. This study assessed the impact of overweight-obesity on LV mass and systolic function in patients with coexistent chronic LV volume overload.

RESEARCH METHODS AND PROCEDURES

In 885 subjects with degenerative aortic regurgitation, a common cause of LV volume overload, LV mass, ejection fraction, and myocardial contractility were determined by echocardiography.

RESULTS

LV mass was greater in overweight (193.5 +/- 54.2 g) and further increased in obese subjects (208.4 +/- 63.6 g) in comparison with normal-weight patients (177.7 +/- 54.9 g) (p < 0.0001), and these differences were still evident after adjustment for LV workload, gender, and body size. Despite no differences in ejection fraction, LV myocardial contractility was lower in overweight (92.6 +/- 14.8%) and obese subjects (91.7 +/- 14.4%) than normal-weight individuals (95.6 +/- 16.0%) (p = 0.0058). The magnitudes of these effects were not different from those found in age-, gender-, and body size-matched controls, suggesting additive interaction, rather than synergistic, between overweight-obesity and the underlying condition of volume overload. Multivariate analysis showed that BMI independently predicted LV mass and that the negative effect on LV myocardial contractility was mediated by LV hypertrophy.

DISCUSSION

Overweight and obesity are associated with LV hypertrophy and contractile impairment in patients with underlying chronic LV volume overload.

Circumferential Versus Longitudinal Systolic Function in Patients with Hypertension: A Nonlinear Relation

BACKGROUND

Depressed circumferential midwall performance and impaired left ventricular (LV) longitudinal function are both early markers of LV systolic dysfunction in patients with hypertension. The relation between midwall and longitudinal indices in these patients has never been analyzed.

METHODS

In 126 patients with hypertension, midwall fractional shortening (mFS), stress-corrected mFS, M-mode left atrioventricular plane displacement, and tissue Doppler-derived peak mitral annular systolic velocity were determined.

RESULTS

Regression analysis showed that the relations of midwall indices to atrioventricular plane displacement and mitral annular systolic velocity were all nonlinear. Reductions in atrioventricular plane displacement or mitral annular systolic velocity within their higher ranges corresponded to relatively smaller decreases in mFS and stress-corrected mFS. Relative wall thickness was the strongest determinant of the relative efficiency of circumferential and longitudinal LV contraction.

CONCLUSION

The relation between circumferential midwall and longitudinal function in patients with hypertension is nonlinear and dependent on LV geometry. In these patients, systolic impairment occurs earlier in longitudinal than circumferential performance.

Mechanics of the normal heart

Even though studies on isolated papillary muscles and cardiomyocytes can be applied to the mechanics of a beating heart, it is not always easy for physicians to relate these findings to clinical medicine. Thus, it is important to extend the studies to intact heart either in simulations or in animal models and even better to validate the results with human subjects. Advances in engineering and computer technology have allowed us to bridge the gap between physiology and mechanics. Cardiomyocyte stress/strain relates to muscle energy expenditure, which dictates oxygen and substrate utilization. Appreciation of this sequential relationship by clinicians will facilitate the logical development and assessment of therapies. Theory of finite element analysis (FEA) can predict cardiac mechanics under normal and pathologic conditions. Imaging studies provide an avenue to relate these predictions indirectly to experimental studies. In this fashion, we can understand the mechanical basis for the micro- and macroanatomical twisting motion of the beating heart. The purposes of this manuscript are: (1) to examine the terms that are traditionally used to describe mechanical stresses and strain within the ventricle, (2) to explore the three-dimensional organization of cardiomyocytes that influences global ventricular function, (3) to apply mechanical measures to both single cardiomyofibrils and the intact ventricle (4) to evaluate mathematical and computer models used to characterize cardiac mechanics, and (5) to outline the clinical methods available to measure ventricular function and relate findings from FEA to pathologic conditions.

Evaluation of Midwall Systolic Function in Left Ventricular Hypertrophy: A Comparison of 3-Dimensional Versus 2-Dimensional Echocardiographic Indices

OBJECTIVE

This study investigated the sensitivity of 3-dimensional (3D) midwall ejection fraction (EF) (3DEF(mw)) to the presence of left ventricular (LV) hypertrophy (LVH) in comparison with conventional echocardiographic indices for systolic function.

BACKGROUND

EF and fractional shortening (FS) do not reflect the prognosis of patients with LVH. Midwall mechanics better represent the true function in LVH. However, midwall FS (FS(mw)) interrogates a limited region of LV. We developed a method for determining 3DEF(mw).

METHODS

This study compared 3DEF(mw) with 2-dimensional (endocardial EF [EF(endo)], endocardial FS, FS(mw), and systolic tissue velocity) and 3D (3D EF(endo) and mitral annular motion [MAM]) echocardiographic indices in 28 patients with essential hypertension and LV mass index by M-mode greater than 125 g/m(2) versus 21 healthy individuals.

RESULTS

Systolic function assessed by EF(endo), endocardial FS, 3D EF(endo), and systolic tissue velocity did not differ between the two groups, but MAM (11.6 vs 14.0 mm), FS(mw) (14.7 vs 18.2%), and 3DEF(mw) (36.6 vs 44.1%) were significantly decreased in LVH compared with normal. Only 3 parameters correlated significantly with both the M-mode and 3D measurements of LV mass index: FS(mw) (r = -0.74 [M-mode]; r = -0.48 [3D]), 3DEF(mw) (r = -0.63 [M-mode]; r = -0.68 [3D]), and MAM (r = -0.43 [M-mode]; r = -0.36 [3D]). Midwall indices FS(mw) (F = 40.4) and 3DEF(mw) (F = 26.5) better discriminated LVH and normal groups than MAM or endocardial indices.

CONCLUSIONS

The 3DEF(mw) method discriminates the systolic function of LVH and normal groups, and correlates with the degree of hypertrophy. By avoiding the limitations of FS(mw) or MAM, 3DEF(mw) provides a more comprehensive metric of systolic function in patients with LVH.