Relation of torsion and myocardial strains to LV ejection fraction in hypertension

Establishment of Cardiac Laterality

Formation of the vertebrate heart with its complex arterial and venous connections is critically dependent on patterning of the left-right axis during early embryonic development. Abnormalities in left-right patterning can lead to a variety of complex life-threatening congenital heart defects. A highly conserved pathway responsible for left-right axis specification has been uncovered. This pathway involves initial asymmetric activation of a nodal signaling cascade at the embryonic node, followed by its propagation to the left lateral plate mesoderm and activation of left-sided expression of the Pitx2 transcription factor specifying visceral organ asymmetry. Intriguingly, recent work suggests that cardiac laterality is encoded by intrinsic cell and tissue chirality independent of Nodal signaling. Thus, Nodal signaling may be superimposed on this intrinsic chirality, providing additional instructive cues to pattern cardiac situs. The impact of intrinsic chirality and the perturbation of left-right patterning on myofiber organization and cardiac function warrants further investigation. We summarize recent insights gained from studies in animal models and also some human clinical studies in a brief overview of the complex processes regulating cardiac asymmetry and their impact on cardiac function and the pathogenesis of congenital heart defects.

Establishment of hypertension risk nomograms based on physical fitness parameters for men and women: a cross-sectional study

Objective

This study aims to establish hypertension risk nomograms for Chinese male and female adults, respectively.

Method

A series of questionnaire surveys, physical assessments, and biochemical indicator tests were performed on 18,367 adult participants in China. The optimization of variable selection was conducted by running cyclic coordinate descent with 10-fold cross-validation through the least absolute shrinkage and selection operator (LASSO) regression. The nomograms were built by including the predictors selected through multivariable logistic regression. Calibration plots, receiver operating characteristic curves (ROC), decision curve analysis (DCA), clinical impact curves (CIC), and net reduction curve plots (NRC) were used to validate the models.

Results

Out of a total of 18 variables, 5 predictors-namely age, body mass index, waistline, hipline, and resting heart rate-were identified for the hypertension risk predictive model for men with an area under the ROC of 0.693 in the training set and 0.707 in the validation set. Seven predictors-namely age, body mass index, body weight, cardiovascular disease history, waistline, resting heart rate, and daily activity level-were identified for the hypertension risk predictive model for women with an area under the ROC of 0.720 in the training set and 0.748 in the validation set. The nomograms for both men and women were externally well-validated.

Conclusion

Gender differences may induce heterogeneity in hypertension risk prediction between men and women. Besides basic demographic and anthropometric parameters, information related to the functional status of the cardiovascular system and physical activity appears to be necessary.

Multi-Ethnic Study of Atherosclerosis: Relationship between Left Ventricular Shape at Cardiac MRI and 10-year Outcomes

Background Left ventricular (LV) subclinical remodeling is associated with adverse outcomes and indicates mechanisms of disease development. Standard metrics such as LV mass and volumes may not capture the full range of remodeling. Purpose To quantify the relationship between LV three-dimensional shape at MRI and incident cardiovascular events over 10 years. Materials and Methods In this retrospective study, 5098 participants from the Multi-Ethnic Study of Atherosclerosis who were free of clinical cardiovascular disease underwent cardiac MRI from 2000 to 2002. LV shape models were automatically generated using a machine learning workflow. Event-specific remodeling signatures were computed using partial least squares regression, and random survival forests were used to determine which features were most associated with incident heart failure (HF), coronary heart disease (CHD), and cardiovascular disease (CVD) events over a 10-year follow-up period. The discrimination improvement of adding LV shape to traditional cardiovascular risk factors, coronary artery calcium scores, and N-terminal pro-brain natriuretic peptide levels was assessed using the index of prediction accuracy and time-dependent area under the receiver operating characteristic curve (AUC). Kaplan-Meier survival curves were used to illustrate the ability of remodeling signatures to predict the end points. Results Overall, 4618 participants had sufficient three-dimensional MRI information to generate patient-specific LV models (mean age, 60.6 years ± 9.9 [SD]; 2540 women). Among these participants, 147 had HF, 317 had CHD, and 455 had CVD events. The addition of LV remodeling signatures to traditional cardiovascular risk factors improved the mean AUC for 10-year survival prediction and achieved better performance than LV mass and volumes; HF (AUC, 0.83 ± 0.01 and 0.81 ± 0.01, respectively; P < .05), CHD (AUC, 0.77 ± 0.01 and 0.75 ± 0.01, respectively; P < .05), and CVD (AUC, 0.78 ± 0.0 and 0.76 ± 0.0, respectively; P < .05). Kaplan-Meier analysis demonstrated that participants with high-risk HF remodeling signatures had a 10-year survival rate of 56% compared with 95% for those with low-risk scores. Conclusion Left ventricular event-specific remodeling signatures were more predictive of heart failure, coronary heart disease, and cardiovascular disease events over 10 years than standard mass and volume measures and enable an automatic personalized medicine approach to tracking remodeling. © RSNA, 2022 Online supplemental material is available for this article.

Anabolic Steroids Use Is Associated with Impairments in Atrial and Ventricular Cardiac Structure and Performance in Athletes

PURPOSE

Despite potential severe cardiac side effects, anabolic androgenic steroids (AAS) are increasingly used by strength athletes. However, previous echocardiographic studies focused on the left ventricular (LV) strains but did not assess LV twist and untwist mechanics. Moreover, left atrial (LA) function has been often neglected, and its stiffness, an important determinant of LA reservoir function, has never been challenged. The aim of this study was to investigate the effects of AAS on LA and LV morphologies and functions in strength athletes.

METHODS

Fifty subjects including 20 strength-trained young athletes age 32.0 ± 8.5 yr with a mean duration of AAS use of 4.7 ± 1.8 yr (users), 15 athletes with no history of AAS use (nonusers) and 15 sedentary controls underwent speckle tracking echocardiography to assess LA and LV morphology and function.

RESULTS

Users showed higher LA reservoir dysfunction than nonusers (33.7% ± 10.9% vs 44.9% ± 9.9% respectively, P = 0.004) and higher LA stiffness (0.13 ± 0.05 vs 0.19 ± 0.08 A.U., respectively; P = 0.02), higher LV mass index and lower global and regional LV diastolic and systolic dysfunction (global longitudinal strain: -15.5% ± 3.2% vs -18.9% ± 1.8% respectively; P = 0.003), with a drop of LV twist-untwist mechanics (untwisting velocity: 61.5°·s-1 ± 20.2°·s-1 vs 73.7°·s-1 ± 16.1°·s-1 respectively, P = 0.04). There were significant correlations between LV mass and LV apical rotation (P = 0.003, r = 0.44) and diastolic longitudinal strain rate (P = 0.015, r = 0.33).

CONCLUSIONS

Our results showing significant LA and LV remodeling and dysfunctions in young AAS using athletes are alarming. Screening echocardiography based on speckle tracking echocardiography parameters for early diagnosis, as well as a stronger awareness in athletes and in physicians are warranted in this context.

Morphological and functional cardiac consequences of rapid hypertension treatment: a cohort study

BACKGROUND

Left ventricular (LV) hypertrophy (LVH) in uncontrolled hypertension is an independent predictor of mortality, though its regression with treatment improves outcomes. Retrospective data suggest that early control of hypertension provides a prognostic advantage and this strategy is included in the 2018 European guidelines, which recommend treating grade II/III hypertension to target blood pressure (BP) within 3 months. The earliest LVH regression to date was demonstrated by echocardiography at 24 weeks. The effect of a rapid guideline-based treatment protocol on LV remodelling, with very early BP control by 18 weeks remains controversial and previously unreported. We aimed to determine whether such rapid hypertension treatment is associated with improvements in LV structure and function through paired cardiovascular magnetic resonance (CMR) scanning at baseline and 18 weeks, utilising CMR mass and feature tracking analysis.

METHODS

We recruited participants with never-treated grade II/III hypertension, initiating a guideline-based treatment protocol which aimed to achieve BP control within 18 weeks. CMR and feature tracking were used to assess myocardial morphology and function immediately before and after treatment.

RESULTS

We acquired complete pre- and 18-week post-treatment data for 41 participants. During the interval, LV mass index reduced significantly (43.5 ± 9.8 to 37.6 ± 8.3 g/m2, p < 0.001) following treatment, accompanied by reductions in LV ejection fraction (65.6 ± 6.8 to 63.4 ± 7.1%, p = 0.03), global radial strain (46.1 ± 9.7 to 39.1 ± 10.9, p < 0.001), mid-circumferential strain (- 20.8 ± 4.9 to - 19.1 ± 3.7, p = 0.02), apical circumferential strain (- 26.0 ± 5.3 to - 23.4 ± 4.2, p = 0.003) and apical rotation (9.8 ± 5.0 to 7.5 ± 4.5, p = 0.003).

CONCLUSIONS

LVH regresses following just 18 weeks of intensive antihypertensive treatment in subjects with newly-diagnosed grade II/III hypertension. This is accompanied by potentially advantageous functional changes within the myocardium and supports the hypothesis that rapid treatment of hypertension could improve clinical outcomes.

TRIAL REGISTRATION

ISRCTN registry number: 57475376 (assigned 25/06/2015).

Morning blood pressure surge in the early stage of hypertensive patients impacts three-dimensional left ventricular speckle tracking echocardiography

BACKGROUND

The aim of this study was to examine left ventricular (LV) function in untreated, newly diagnosed hypertensive patients with morning blood pressure surge (MBPS) status using three-dimensional (3D) speckle tracking echocardiography (STE).

METHODS

In this study, 163 newly diagnosed hypertensive patients were included, and all patients underwent 24-h ambulatory blood pressure monitoring (ABPM). According to ABPM, participants were divided into a MBPS group and a non-MBPS group. The entire study population was examined by complete two-dimensional (2D) transthoracic echocardiography (TTE) and 3D STE.

RESULT

The results of this study showed that 3D LV longitudinal strain was significantly decreased in the MBPS group compared with the non-MBPS group (- 30.1 ± 2.0 vs. -31.1 ± 2.7, p = 0.045). Similar trends were observed for 3D twist (9.6 ± 6.1 vs. 12.1 ± 4.8, p = 0.011) as well as for 3D torsion (1.23 ± 0.78 vs. 1.49 ± 0.62, p = 0.042). The LV principal strain was decreased in the MBPS group (- 33.9 ± 1.7 vs. -35.5 ± 2.8, p < 0.001). The 3D LV global longitudinal strain (GLS) and principal strain were significantly associated with quartile of MBPS as measured by systolic blood pressure (SBP).

CONCLUSION

The 3D STE revealed that LV mechanics were more impaired in the MBPS group than in the non-surge newly diagnosed, untreated hypertensive patients; even the 2D TTE parameters showed no difference.

Impact of gender on left ventricular deformation in patients with essential hypertension assessed by cardiac magnetic resonance tissue tracking

Left ventricular (LV) myocardial strain impairment has been demonstrated in hypertension despite normal LV ejection fraction (LVEF); however, limited data exist on any difference in results between genders. The aim of this study was to investigate the impact of gender on LV deformation in patients with essential hypertension. This was a cross-sectional study, in which 94 patients (47 men and 47 women) with essential hypertension and 62 age- and gender-matched controls (31 men and 31 women) were enrolled. A 3.0 T/two-dimensional balanced steady-state free precession cine, late gadolinium enhancement was used. The LV endocardial and epicardial contours were drawn by radiologists, then LV volumes, mass, function, and myocardial strain, including peak global radial (GRS), circumferential (GCS), and longitudinal strain (GLS) were automatically calculated. Chi-square test, Student's t-test, general linear model analysis, univariate linear regression analysis, stepwise multivariate linear regression analysis, and intraclass correlation coefficient analysis were performed. Women had significantly higher magnitudes of LV GRS, GCS, and GLS than men in both patients and controls (all p < 0.05). In the overall patients, LV GLS was significantly reduced compared with controls (p < 0.05), while GRS and GCS were preserved (p = 0.092 and 0.27, respectively). Compared with their counterpart controls, LV GRS, GCS, and GLS (all p < 0.05) were significantly reduced in hypertensive men, while only GLS (p < 0.05) was reduced in hypertensive women. Male gender and its interaction with hypertension were associated with higher LV mass and volume, decreased LV GRS, GCS, and GLS compared with hypertensive women. Multivariate analyses revealed that gender and LVEF were independently associated with GRS, GCS, and GLS (all p < 0.001) in hypertension. LV deformation is significantly reduced in hypertension, and gender may influence the response of LV deformation to hypertension, with men suffering more pronounced subclinical myocardial dysfunction. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 3.

Cardiac MRI Assessment of Mouse Myocardial Infarction and Regeneration

Small animal models are indispensable for cardiac regeneration research. Studies in mouse and rat models have provided important insights into the etiology and mechanisms of cardiovascular diseases and accelerated the development of therapeutic strategies. It is vitally important to be able to evaluate the therapeutic efficacy and have reliable surrogate markers for therapeutic development for cardiac regeneration research. Magnetic resonance imaging (MRI), a versatile and noninvasive imaging modality with excellent penetration depth, tissue coverage, and soft-tissue contrast, is becoming a more important tool in both clinical settings and research arenas. Cardiac MRI (CMR) is versatile, noninvasive, and capable of measuring many different aspects of cardiac functions, and, thus, is ideally suited to evaluate therapeutic efficacy for cardiac regeneration. CMR applications include assessment of cardiac anatomy, regional wall motion, myocardial perfusion, myocardial viability, cardiac function assessment, assessment of myocardial infarction, and myocardial injury. Myocardial infarction models in mice are commonly used model systems for cardiac regeneration research. In this chapter, we discuss various CMR applications to evaluate cardiac functions and inflammation after myocardial infarction.

Joint influences of obesity, diabetes, and hypertension on indices of ventricular remodeling: Findings from the community-based Framingham Heart Study

Introduction

Obesity, hypertension, and diabetes are independently associated with cardiac remodeling and frequently co-cluster. The conjoint and separate influences of these conditions on cardiac remodeling have not been investigated.

Materials and methods

We evaluated 5,741 Framingham Study participants (mean age 50 years, 55% women) who underwent echocardiographic measurements of left ventricular (LV) mass (LVM), LV ejection fraction (LVEF), global longitudinal strain (GLS), mitral E/e’, left atrial end-systolic (peak) dimension (LASD) and emptying fraction (LAEF). We used multivariable generalized linear models to estimate the adjusted-least square means of these measures according to cross-classified categories of body mass index (BMI; normal, overweight and obese), hypertension (yes/no), and diabetes (yes/no).

Results

We observed statistically significant interactions of BMI category, hypertension, and diabetes with LVM, LVEF, GLS, and LAEF (p for all 3-way interactions <0.01). Overweight and obesity (compared to normal BMI), hypertension, and diabetes status were individually and conjointly associated with higher LVM and worse GLS (p<0.01 for all). We observed an increase of 34% for LVM and of 9% for GLS between individuals with a normal BMI and without hypertension or diabetes compared to obese individuals with hypertension and diabetes. Presence of hypertension was associated with higher LVEF, whereas people with diabetes had lower LVEF.

Conclusions

Obesity, hypertension, and diabetes interact synergistically to influence cardiac remodeling. These findings may explain the markedly heightened risk of heart failure and cardiovascular disease when these factors co-cluster.

Myocardial strain indices and coronary flow reserve are only mildly affected in healthy hypertensive patients

To investigate changes in two-dimensional myocardial strain echocardiography (2DSTE) indices following a dipyridamole stress test (DIPSE) in relatively healthy hypertensive patients and healthy controls. Forty-seven male hypertensive patients (aged 57±9 years) with normal ejection fraction and without left ventricular (LV) hypertrophy and 20 healthy male subjects were studied with conventional and 2DSTE echocardiography at rest and post DIPSE. Coronary flow reserve (CFR) in the left anterior descending artery following DIPSE was also evaluated. Global longitudinal strain (GLS) and TWIST were higher while UNTWIST rate was lower in hypertensives versus controls (p < 0.05 for all); TWIST remained higher in hypertensives (p = 0.021) after adjustment for differences in age and body mass index (BMI) between the groups. CFR was higher in controls compared to hypertensives even after adjustment for confounders (4.14 vs. 2.53, p = 0.001). DIPSE-induced changes did not differ between the groups after adjustment for age and BMI (p > 0.05 for all). DIPSE-induced improvement in GLS was associated with higher CFR only in hypertensive patients (r - 0.372, p = 0.010). The current study showed that well controlled hypertensive patients have only mild echocardiographic differences compared to controls; some of these differences appear to depend on age and BMI. A 'hyper-rotation' phenomenon (i.e. higher TWIST) early in hypertension may be a compensatory mechanism to preserve global systolic LV function. Coronary microcirculatory function was impaired in hypertensive patients, albeit within normal range, and was associated with DIPSE-induced changes in myocardial long-axis systolic function.

Impact of medical therapy for cardiovascular disease on left ventricular diastolic properties and remodeling

Background

Left ventricular (LV) remodeling and diastolic properties are affected by both underlying cardiovascular disease/cardiovascular disease risk factors (CVDRFs) and corresponding medication therapy. However, these effects may not be apparent in patients with multiple CVDRFs. We evaluated the effect of medication classes on hemodynamics in a patient cohort with normal LV dimensions and systolic function.

Methods

In 38 participants (61 ± 7 years, 64 ± 9% LV ejection fraction) undergoing coronary angiography, LV pressure measurement and cardiac magnetic resonance imaging was performed. The effects of coronary artery disease (CAD), CVDRFs and their corresponding medication therapy on LV parameters were analyzed considering the number of CAD/CVDRFs and ‘adequacy’ of medication therapy to address each existing condition with specific indication-based medication classes.

Results

Of the patients studied, 68% had CAD, 87% had hypertension, 87% had dyslipidemia, and 45% had diabetes. Neither individual or total number of CAD/CVDRFs were associated with overall differences in LV diastolic parameters. However, those without (n = 20) and with (n = 18) ‘adequate’ medication therapy for underlying CAD/CVDRFs differed in values of LV end diastolic pressure (17 ± 4 vs. 11 ± 5 mm Hg, P < 0.001), wall stress (3.9 ± 1.6 vs. 2.2 ± 1.2 x1000 N/m², P < 0.001), pressure/volume ratio (0.13 ± 0.04 vs. 0.08 ± 0.03 mm Hg/ml, P < 0.01), and mass/volume ratio (0.77 ± 0.20 vs. 0.92 ± 0.24 g/ml, P < 0.05), but not in systolic blood pressure or LV mass index.

Conclusions

Our results suggest an association between the degree of LV diastolic impairment and LV remodeling with the intensity of treatment for CAD/CVDRFs. Comprehensive treatment of all identified CAD/CVDRFs may be an important factor for the preservation of diastolic function.

Concomitant systolic and diastolic alterations during chronic hypertension in pig

The mechanical and cellular relationships between systole and diastole during left ventricular (LV) dysfunction remain to be established. LV contraction-relaxation coupling was examined during LV hypertrophy induced by chronic hypertension. Chronically instrumented pigs received angiotensin II infusion for4weeks to induce chronic hypertension (133 ± 7 mmHg vs 98 ± 5 mmHg for mean arterial pressure at Day 28 vs 0, respectively) and LV hypertrophy. LV function was investigated with the instrumentation and echocardiography for LV twist-untwist assessment before and after dobutamine infusion. The cellular mechanisms were investigated by exploring the intracellular Ca²⁺ handling. At Day 28, pigs exhibited LV hypertrophy with LV diastolic dysfunction (impaired LV isovolumic relaxation, increased LV end-diastolic pressure, decreased and delayed LV untwisting rate) and LV systolic dysfunction (impaired LV isovolumic contraction and twist) although LV ejection fraction was preserved. Isolated cardiomyocytes exhibited altered shortening and lengthening. Interestingly, contraction-relaxation coupling remained preserved both in vivo and in vitro during LV hypertrophy. LV systolic and diastolic dysfunctions were associated to post-translational remodeling and dysfunction of the type 2 cardiac ryanodine receptor/Ca²⁺ release channel (RyR2), i.e., PKA hyperphosphorylation of RyR2, depletion of calstabin 2 (FKBP12.6), RyR2 leak and hypersensitivity of RyR2 to cytosolic Ca²⁺ during both contraction and relaxation phases. In conclusion, LV contraction-relaxation coupling remained preserved during chronic hypertension despite LV systolic and diastolic dysfunctions. This implies that LV diastolic dysfunction is accompanied by LV systolic dysfunction. At the cellular level, this is linked to sarcoplasmic reticulum Ca²⁺ leak through PKA-mediated RyR2 hyperphosphorylation and depletion of its stabilizing partner.

Recent Advances in Imaging of Hypertensive Heart Disease

PURPOSE OF REVIEW

To review recent advances in the imaging of hypertensive heart disease (HHD) with an emphasis on developments in the imaging of diffuse myocardial fibrosis using cardiac magnetic resonance (CMR).

RECENT FINDINGS

HHD results from long-standing hypertension and is characterized by the development of left ventricular hypertrophy and diffuse interstitial fibrosis. Diffuse fibrosis traditionally required endomyocardial biopsy to diagnose, but recent developments using T1 mapping in CMR allow for noninvasive assessment. Studies using T1 mapping have shown an increase in extracellular volume fraction (ECV) in patients with HHD compared to normal controls, suggesting ECV can be used as a noninvasive marker for fibrosis in HHD. In addition to T1 mapping, other recent advances in HHD imaging include improvements in three-dimensional echocardiography, allowing for accurate real-time volumetric measurements, and the use of speckle tracking echocardiography to detect subclinical systolic dysfunction. Measurement of ECV using T1 mapping in CMR can be used as a noninvasive marker of diffuse myocardial fibrosis in HHD. While further studies are needed to validate this approach with larger patient cohorts, ECV can potentially be used to both monitor disease progression and assess therapeutic interventions in HHD.

Evaluation of Left Ventricular Systolic Function and Mass in Primary Hypertensive Patients by Echocardiography

Hypertension is an independent risk factor for cardiovascular diseases. The accurate evaluation of cardiovascular risk is of paramount importance in the management of hypertensive patients. Conventional echocardiographic methods have provided the assessment of left ventricular systolic function and mass for many years. Tissue Doppler imaging, 3-dimensional echocardiography, and speckle tracking echocardiography are newer echocardiographic modalities for the left ventricular systolic function and mass quantification. The major emphasis of this review is to evaluate the left ventricular systolic function and mass by conventional and newly developed echocardiographic in hypertensive patients.

Relation of arterial stiffness to left ventricular structure and function in healthy women

BACKGROUND

Interactions between the left ventricular (LV) and the arterial system, (ventricular-arterial coupling) are key determinants of cardiovascular function. However, most of studies covered multiple cardiovascular risk factors, which also contributed to the morphological and functional changes of LV. The aim of this study was to examine the relationship between arterial stiffness and LV structure and function in healthy women with a low burden of risk factors.

METHODS

Healthy women from the Twins UK cohort (n = 147, mean age was 54.07 ± 11.90 years) were studied. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cf-PWV). LV structure and function were assessed by two-dimensional speckle tracking echocardiography.

RESULTS

cf-PWV was significantly associated with most measures of LV geometry and function, including relative wall thickness (RWT), E/e' ratio, global circumferential and radial strain, apical rotation and LV twist (each p <  0.05), but bore no relation to global longitudinal strain. After adjustment for age, body mass index, blood pressure and heart rate, cf-PWV was significantly correlated with RWT, global circumferential strain, apical rotation and LV twist (β = 0.011, - 0.484, 1.167 and 1.089, respectively, each p ≤  0.05).

CONCLUSIONS

In healthy women with a low burden of risk factors, elevated arterial stiffness was intimately interwoven with increased LV twisting even before LV dysfunction becomes clinically evident.

Differential Effects of Isoproterenol on Regional Myocardial Mechanics in Rat using 3D cine DENSE Cardiovascular Magnetic Resonance

The present study assessed the acute effects of isoproterenol on left ventricular (LV) mechanics in healthy rats with the hypothesis that ß-adrenergic stimulation influences the mechanics of different myocardial regions of the LV wall in different ways. To accomplish this, magnetic resonance images were obtained in the LV of healthy rats with or without isoproterenol infusion. The LV contours were divided into basal, mid-ventricular, and apical regions. Additionally, the mid-ventricular myocardium was divided into three transmural layers with each layer partitioned into four segments (i.e., septal, inferior, lateral, and anterior). Peak systolic strains and torsion were quantified for each region. Isoproterenol significantly increased peak systolic radial strain and circumferential-longitudinal shear strain, as well as ventricular torsion, throughout the basal, mid-ventricle, and apical regions. In the mid-ventricle, isoproterenol significantly increased peak systolic radial strain, and induced significant increases in peak systolic circumferential strain and longitudinal strain in the septum. Isoproterenol consistently increased peak systolic circumferential-longitudinal shear strain in all mid-ventricular segments. Ventricular torsion was significantly increased in nearly all segments except the inferior sub-endocardium. The effects of isoproterenol on LV systolic mechanics (i.e., 3D strains and torsion) in healthy rats depend on the region. This region-dependency is also strain component-specific. These results provide insight into the regional response of LV mechanics to ß-adrenergic stimulation in rats, and could act as a baseline for future studies on subclinical abnormalities associated with the inotropic response in heart disease.

Refractory Hypertension Is not Attributable to Intravascular Fluid Retention as Determined by Intracardiac Volumes

Refractory hypertension (RfHTN) is an extreme phenotype of antihypertensive treatment failure defined as lack of blood pressure control with ≥5 medications, including a long-acting thiazide and a mineralocorticoid receptor antagonist. RfHTN is a subgroup of resistant hypertension (RHTN), which is defined as blood pressure >135/85 mm Hg with ≥3 antihypertensive medications, including a diuretic. RHTN is generally attributed to persistent intravascular fluid retention. It is unknown whether alternative mechanisms are operative in RfHTN. Our objective was to determine whether RfHTN is characterized by persistent fluid retention, indexed by greater intracardiac volumes determined by cardiac magnetic resonance when compared with controlled RHTN patients. Consecutive patients evaluated in our institution with RfHTN and controlled RHTN were prospectively enrolled. Exclusion criteria included advanced chronic kidney disease and masked or white coat hypertension. All enrolled patients underwent biochemical testing and cardiac magnetic resonance. The RfHTN group (n=24) was younger (mean age, 51.7±8.9 versus 60.6±11.5 years; P=0.003) and had a greater proportion of women (75.0% versus 43%; P=0.02) compared with the controlled RHTN group (n=30). RfHTN patients had a greater left ventricular mass index (88.3±35.0 versus 54.6±12.5 g/m²; P<0.001), posterior wall thickness (10.1±3.1 versus 7.7±1.5 mm; P=0.001), and septal wall thickness (14.5±3.8 versus 10.0±2.2 mm; P<0.001). There was no difference in B-type natriuretic peptide levels and left atrial or ventricular volumes. Diastolic dysfunction was noted in RfHTN. Our findings demonstrate greater left ventricular hypertrophy without chamber enlargement in RfHTN, suggesting that antihypertensive treatment failure is not attributable to intravascular volume retention.

Left ventricular twist before and after haemodialysis: an analysis using speckle-tracking echocardiography

Background

The most commonly used parameter of cardiac function in the chronic kidney disease (CKD) patient is ejection fraction (EF), using transthoracic echocardiography (TTE). EF is a highly load-dependent measurement, which varies considerably in CKD patients undergoing haemodialysis. The aim of this pilot study was to evaluate a novel measure of myocardial function, left ventricular twist, which is defined as the ‘wringing action of the heart’, using speckletracking echocardiography in CKD patients before and after haemodialysis.

Methods

Twenty-six patients were recruited from the Chris Hani Baragwanath Hospital haemodialysis unit. TTE was performed according to a detailed standardised protocol before and after a single haemodialysis session. Echocardiography was also performed on 26 age- and gendermatched healthy subjects.

Results

The mean age of the control versus CKD group was 44 ± 11.4 and 43.4 ± 12.2 years, respectively; 46% were male. Apical rotation was diminished in CKD patients compared to controls (4.83 ± 2.3 vs 6.31 ± 1.6 °; p = 0.01) despite no difference in EF (61.7 ± 6.2 vs 58.8 ± 13; p = 0.68). There were no differences in the components of twist: apical rotation, basal rotation and net twist before and after dialysis, despite an increase in EF (58.8 ± 13.7 vs 61.2 ± 13.6; p = 0.02) following dialysis.

Conclusion

Unlike EF, the components of twist are relatively independent of changes in haemodynamic load seen during dialysis. The decrease in apical rotation may represent an early marker of cardiac pathology in the late-stage CKD patient.

Left Ventricular Torsion Associated With Aortic Stiffness in Hypertension

BACKGROUND

Left ventricular (LV) torsion plays a key role in cardiac efficiency. In hypertension, aortic stiffening augments cardiac afterload. However, little is known about the links between LV regional contraction and aortic stiffness. We, therefore, investigated these relationships and their contribution to LV diastolic function.

METHODS AND RESULTS

The study included normotensive and hypertensive individuals with normal LV ejection. Apical, basal, and global LV rotation rate and LV global longitudinal strain were measured (2-dimensional speckle tracking echocardiography). Aortic stiffness was calculated from carotid-femoral pulse wave velocity, and LV relaxation was calculated from early diastolic mitral annulus motion. The ratio of basal or apical untwist/twist rates was calculated to assess relationships between aortic stiffness and LV torsion parameters. LV twist and untwist rates were greater in hypertensive than normotensive individuals because of increased basal twist (P<0.001) and untwist (P<0.001) rates. LV relaxation was reduced (early diastolic mitral annulus motion=7.4±1.9 versus 10.4±2.3 cm/s; P<0.001). In the whole population, basal untwist rate increased with aortic stiffening (R=0.43; P<0.001) and LV relaxation (R=0.41; P=0.001). The ratio of basal untwist/twist rate was positively correlated with carotid-femoral pulse wave velocity, and in the hypertensive group, was greater than in the control group and positively correlated to carotid-femoral pulse wave velocity(P<0.001). Results were independent of age, treatment, mean blood pressure, and indexed LV mass.

CONCLUSIONS

In hypertensive individuals, greater basal LV torsion was associated with increased aortic stiffness and improved diastolic function. These changes may compensate for the deleterious effects of aortic stiffening on LV relaxation.

Preserved Myocardial Deformation after Successful Coarctation Repair: A CMR Feature-Tracking Study

Arterial vasculopathy and residual aortic obstruction can lead to left ventricular (LV) dysfunction in patients with coarctation of the aorta (CoA) related to adverse ventriculo-arterial coupling. This study aimed to investigate potential differences in LV myocardial deformation indices between repaired CoA patients and healthy controls. Twenty-two CoA patients (age 30 ± 10.6 years) after surgical repair (n = 12) or balloon angioplasty (BA) (n = 10) without residual stenosis, between 3 months and 16 years of age with > 10 years follow-up were compared to 22 healthy age- and gender-matched controls (age 30 ± 3.8 years). Cardiac magnetic resonance feature tracking (CMR-FT) was used for LV longitudinal-, circumferential-, and rotational deformation indices. Global systolic LV function was preserved in CoA patients (LV ejection fraction 58 ± 4.8 vs. 60 ± 6.8%, p = 0.56) when compared to controls, with normal LV dimensions and mass (p > 0.05). Twelve CoA patients (55%) were hypertensive, of whom 4 were on anti-hypertensive medication. LV global longitudinal strain was preserved in the four-chamber (- 18 ± 4.4 vs. - 16 ± 4.7%, p = 0.06) and two-chamber (- 22 ± 5.1 vs. - 20 ± 6.0%, p = 0.22) orientations in CoA patients. Global circumferential strain was preserved at basal (- 29 ± 4.1 vs. - 28 ± 4.8%, p = 0.43), mid-ventricular (- 27 ± 4.2 vs. - 25 ± 3.0%, p = 0.09), and apical levels (- 35 ± 7.8 vs. - 32 ± 34.9%, p = 0.32). No differences were found in global torsion (2.4 ± 1.3° vs. 2.0 ± 1.4°/cm, p = 0.28), twist (14 ± 5.8° vs. 12 ± 6.3°, p = 0.34), and recoil rate (- 17 ± 9.7° vs. - 17 ± 7.1°/cm s, p = 0.97). Analysis of intra-observer variability demonstrated good reproducibility for all CMR deformation indices. Global and rotational myocardial deformation indices are preserved in CoA patients long-term after repair without residual stenosis, despite a high incidence of hypertension.

Left Ventricular Torsion Shear Angle Volume Approach for Noninvasive Evaluation of Diastolic Dysfunction in Preserved Ejection Fraction

BACKGROUND

Accurate noninvasive diagnostic tools for evaluating left ventricular (LV) diastolic dysfunction (LVDD) are limited in preserved LV ejection fraction. We previously proposed the relationship of normalized rate of change in LV torsion shear angle (φ') to corresponding rate of change in LV volume (V') during early diastole (represented as -dφ'/dV') as a measure of LV diastolic function. We prospectively evaluated diagnostic accuracy of -dφ'/dV' in respect to invasive LV parameters.

METHODS AND RESULTS

Participants (n=36, age 61±7 years) with LV ejection fraction ≥50% and no acute myocardial infarction undergoing coronary angiography for chest pain and/or dyspnea evaluation were studied. High-fidelity invasive LV pressure measurements and cardiac magnetic resonance imaging with tissue tagging were performed. τ, the time constant of LV diastolic relaxation, was 58±10 milliseconds (mean±SD), and LV end-diastolic pressure was 14.5±5.5 mm Hg. Cardiac magnetic resonance imaging-derived -dφ'/dV' was 5.6±3.7. The value of -dφ'/dV' correlated with both τ and LV end-diastolic pressure (r=0.39 and 0.36, respectively, P<0.05). LVDD was defined as τ>48 milliseconds and LV end-diastolic pressure >12 mm Hg (LVDD1), or, alternatively, τ>48 milliseconds and LV end-diastolic pressure >16 mm Hg (LVDD2). Area under the curve (AUC) of -dφ'/dV' for identifying LVDD1 was 0.83 (0.67-0.98, P=0.001), with sensitivity/specificity of 72%/100% for -dφ'/dV' ≥6.2. AUC of -dφ'/dV' for identifying LVDD_2 was 0.82 (0.64-1.00, P=0.006), with sensitivity/specificity of 76%/85% for -dφ'/dV' ≥6.9. There were good limits of agreement between pre- and post-nitroglycerin -dφ'/dV'.

CONCLUSIONS

The -dφ'/dV' obtained from the LV torsion volume loop is a promising parameter for assessing global LVDD with preserved LV ejection fraction and requires further evaluation.

Left ventricular torsion in patients with obstructive sleep apnoea before and after continuous positive airway pressure therapy: assessment by two-dimensional speckle tracking echocardiography

BACKGROUND

The purpose of the present study was to evaluate how obstructive sleep apnoea (OSA) influences left ventricular (LV) torsion and whether nasal continuous positive airway pressure (CPAP) therapy has any impact on LV torsion in OSA patients with established cardiovascular risk factors.

METHODS

LV torsion was assessed by two-dimensional speckle tracking echocardiography (STE) in 162 participants without overt cardiovascular disease. The participants were categorized according to the apnoea-hypopnea index (AHI) as controls and mild, moderate and severe OSA patients. Forty-three patients with AHI greater than 30 were enrolled to receive CPAP therapy for 24 weeks. Twenty-eight patients received CPAP therapy effectively (compliance: 65%). After completion of CPAP therapy, STE was repeated to evaluate LV torsion.

RESULTS

LV torsion was decreased in the severe OSA group compared to mild and moderate OSA but was similar to controls as a result of predominant decrease in apical rotation. AHI had no correlation with LV torsion in moderate OSA but a significant and mild negative correlation with LV torsion in severe OSA. When adjusted for potential confounding variables such as left ventricular mass index, diastolic dysfunction and the presence of hypertension, AHI and E/E' remained significant predictors of LV torsion in OSA patients. LV apical rotation tended to increase after effective CPAP therapy. On the other hand, LV basal rotation decreased significantly.

CONCLUSIONS

LV torsion was altered in OSA patients with varying degrees according to the disease severity. Furthermore, there was no significant change of torsion after 24 weeks of CPAP therapy.

Clinical feasibility and validation of 3D principal strain analysis from cine MRI: comparison to 2D strain by MRI and 3D speckle tracking echocardiography

Two-dimensional (2D) strain analysis is constrained by geometry-dependent reference directions of deformation (i.e. radial, circumferential, and longitudinal) following the assumption of cylindrical chamber architecture. Three-dimensional (3D) principal strain analysis may overcome such limitations by referencing intrinsic (i.e. principal) directions of deformation. This study aimed to demonstrate clinical feasibility of 3D principal strain analysis from routine 2D cine MRI with validation to strain from 2D tagged cine analysis and 3D speckle tracking echocardiography. Thirty-one patients undergoing cardiac MRI were studied. 3D strain was measured from routine, multi-planar 2D cine SSFP images using custom software designed to apply 4D deformation fields to 3D cardiac models to derive principal strain. Comparisons of strain estimates versus those by 2D tagged cine, 2D non-tagged cine (feature tracking), and 3D speckle tracking echocardiography (STE) were performed. Mean age was 51 ± 14 (36% female). Mean LV ejection fraction was 66 ± 10% (range 37–80%). 3D principal strain analysis was feasible in all subjects and showed high inter- and intra-observer reproducibility (ICC range 0.83–0.97 and 0.83–0.98, respectively—p < 0.001 for all directions). Strong correlations of minimum and maximum principal strain were respectively observed versus the following: 3D STE estimates of longitudinal (r = 0.81 and r = −0.64), circumferential (r = 0.76 and r = −0.58) and radial (r = −0.80 and r = 0.63) strain (p < 0.001 for all); 2D tagged cine estimates of longitudinal (r = 0.81 and r = −0.81), circumferential (r = 0.87 and r = −0.85), and radial (r = −0.76 and r = 0.81) strain (p < 0.0001 for all); and 2D cine (feature tracking) estimates of longitudinal (r = 0.85 and −0.83), circumferential (r = 0.88 and r = −0.87), and radial strain (r = −0.79 and r = 0.84, p < 0.0001 for all). 3D principal strain analysis is feasible using routine, multi-planar 2D cine MRI and shows high reproducibility with strong correlations to 2D conventional strain analysis and 3D STE-based analysis. Given its independence from geometry-related directions of deformation this technique may offer unique benefit for the detection and prognostication of myocardial disease, and warrants expanded investigation.

Left ventricular functional, structural and energetic effects of normal aging: Comparison with hypertension

Objectives

Both aging and hypertension are significant risk factors for heart failure in the elderly. The purpose of this study was to determine how aging, with and without hypertension, affects left ventricular function.

Methods

Cross-sectional study of magnetic resonance imaging and ³¹P spectroscopy-based measurements of left ventricular structure, global function, strains, pulse wave velocity, high energy phosphate metabolism in 48 normal subjects and 40 treated hypertensive patients (though no other cardiovascular disease or diabetes) stratified into 3 age deciles from 50–79 years.

Results

Normal aging was associated with significant increases in systolic blood pressure, vascular stiffness, torsion, and impaired diastolic function (all P<0.05). Age-matched hypertension exacerbated the effects of aging on systolic pressure, and diastolic function. Hypertension alone, and not aging, was associated with increased left ventricular mass index, reduced energetic reserve, reduced longitudinal shortening and increased endocardial circumferential shortening (all P<0.05). Multiple linear regression analysis showed that these unique hypertensive features were significantly related to systolic blood pressure (P<0.05).

Conclusions

1) Hypertension adds to the age-related changes in systolic blood pressure and diastolic function; 2) hypertension is uniquely associated with changes in several aspects of left ventricular structure, function, systolic strains, and energetics; and 3) these uniquely hypertensive-associated parameters are related to the level of systolic blood pressure and so are potentially modifiable.

Left Ventricular Function Assessed by One-Point Carotid Wave Intensity in Newly Diagnosed Untreated Hypertensive Patients

OBJECTIVES

To investigate whether newly diagnosed untreated hypertensive patients show higher left ventricular (LV) contractility, as assessed by traditional echocardiographic indices and carotid wave intensity (WI) parameters, including amplitude of the peak during early (W₁ ) and late systole (W₂ ).

METHODS

A total of 145 untreated hypertensive patients were compared with 145 age- and sex-matched normotensive subjects. They underwent comprehensive echocardiography and WI analysis. WI analysis was performed at the level of the common carotid artery. The diameter changes were the difference between the displacement of the anterior and posterior walls, with the cursors set to track the media-adventitia boundaries 2 cm proximal to the carotid bulb and calibrated by systolic and diastolic BP. Peak acceleration was derived from blood flow velocity measured by Doppler sonography with the range-gate positioned at the center of the vessel diameter. WI was based on the calculation of (dP/dt)×(dU/dt), where dP/dt and dU/dt were the derivatives of BP (P) and velocity (U) with respect to time. One-point pulse wave velocity (PWVβ) and the interval between the R wave on ECG and the first peak of WI (R-W₁ ), using a high definition echo-tracking system implemented in the ultrasound machine (Aloka), were also derived.

RESULTS

After adjustment for body weight, heart rate, and physical activity, the two groups had similar general characteristics and diastolic function. However, hypertensives showed significantly higher LV mass, LV ejection fraction (LVEF), circumferential and LV end-systolic stress, and one-point PWV as well as W₁ (13.646 ± 7.368 vs 9.308 ± 4.675 mmHg m/s³ , P =.001) and W₂ (4.289 ± 2.017 vs 2.995 ± 1.868 mmHg m/s³ , P =.001). Hypertensives were divided into tertiles according to LVEF: W₁ (11.934 ± 5.836 vs 11.576 ± 5.857 vs 17.227 ± 8.889 mmHg m/s³ , P <.0001) was higher in the highest LVEF tertile along with relative wall thickness, midwall fractional shortening, endocardial fractional shortening, and R-W₁ .

CONCLUSIONS

Newly diagnosed hypertensives show increased LVM and LV contractility, including carotid WI parameters and R-W₁ values, as compared with normotensive subjects, but no differences in LV diastolic function.

Cardiac Imaging in Heart Failure with Comorbidities

Imaging modalities stand at the frontiers for progress in congestive heart failure (CHF) screening, risk stratification and monitoring. Advancements in echocardiography (ECHO) and Magnetic Resonance Imaging (MRI) have allowed for improved tissue characterizations, cardiac motion analysis, and cardiac performance analysis under stress. Common cardiac comorbidities such as hypertension, metabolic syndromes and chronic renal failure contribute to cardiac remodeling, sharing similar pathophysiological mechanisms starting with interstitial changes, structural changes and finally clinical CHF. These imaging techniques can potentially detect changes earlier. Such information could have clinical benefits for screening, planning preventive therapies and risk stratifying patients. Imaging reports have often focused on traditional measures without factoring these novel parameters. This review is aimed at providing a synopsis on how we can use this information to assess and monitor improvements for CHF with comorbidities.

Left ventricular shape predicts different types of cardiovascular events in the general population

OBJECTIVE

To investigate whether sphericity volume index (SVI), an indicator of left ventricular (LV) remodelling, predicts incident cardiovascular events (coronary heart disease, CHD; all cardiovascular disease, CVD; heart failure, HF; atrial fibrillation, AF) over 10 years of follow-up in a multiethnic population (Multi-Ethnic Study of Atherosclerosis).

METHODS

5004 participants free of known CVD had magnetic resonance imaging (MRI) in 2000-2002. Cine images were analysed to compute, [Formula: see text] equivalent to LV volume/volume of sphere with length of LV as the diameter. The highest (greatest sphericity) and lowest (lowest sphericity) quintiles of SVI were compared against the reference group (2-4 quintiles combined). Risk-factor adjusted hazard's ratio (HR) from Cox regression assessed the predictive performance of SVI at end-diastole (ED) and end-systole (ES) to predict incident outcomes over 10 years in retrospective interpretation of prospective data.

RESULTS

At baseline, participants were aged 61±10 years; 52% men and 39%/13%/26%/22% Cauc/Chinese/Afr-Amer/Hispanic. Low sphericity was associated with higher Framingham CVD risk, greater coronary calcium score and higher N-terminal pro-brain natriuretic peptide (NT-proBNP); while increased sphericity was associated with higher NT-proBNP and lower ejection fraction. Low sphericity predicted incident CHD (HR: 1.48, 1.55-2.59 at ED) and CVD (HR: 1.82, 1.47-2.27 at ED). However, both low (HR: 1.81, 1.20-2.73 at ES) and high (HR: 2.21, 1.41-3.46 at ES) sphericity predicted incident HF. High sphericity also predicted AF.

CONCLUSIONS

In a multiethnic population free of CVD at baseline, lowest sphericity was a predictor of incident CHD, CVD and HF over a 10-year follow-up period. Extreme sphericity was a strong predictor of incident HF and AF. SVI improved risk prediction models beyond established risk factors only for HF, but not for all CVD or CHD.

Left ventricular torsion and circumferential strain responses to exercise in patients with ischemic coronary artery disease

LV torsion during exercise in patients with coronary artery disease (CAD) is not well known. Circumferential strain (CS) and left ventricular (LV) torsion (Tor) have not been evaluated during ischemia in these patients. We aimed to assess the effect of ischemia during exercise echocardiography (ExE) on CS and Tor. We studied a group of 73 patients with true positive ExE results (Ischemic group: ischemia plus an abnormal coronary angiogram) and a matched control group of 66 patients with negative ExE and either normal coronary angiography or low post-test probability of CAD. Basal rotation (Rot) and apical rotation and basal and apical CS were studied by speckle tracking at rest and exercise. Apical CS and apical and basal Rot values were similar between groups at rest, except basal CS which was already worse in the ischemic group. At exercise, all rotational and CS parameters were impaired in the ischemic in comparison with the control group (basal CS: -18 ± 5 vs. -25 ± 7 %, p < 0.001; apical CS: -31 ± 11 vs. - 43 ± 9 %, p < 0.001; time to basal CS: 52 ± 6 vs. 48 ± 7 %, p = 0.001; time to apical CS: 55 ± 7 vs. 49 ± 6 %, p < 0.001; basal rotation: -0.7 ± 6.5° vs. -6.2 ± 8.5°, p < 0.001; LV twist 13.0 ± 10.4° vs.19.7 ± 11.5°, p < 0.001; LV-Tor 1.9 ± 1.6°/cm vs. 2.8 ± 1.7˚/cm, p = 0.001) with the exception of apical rotation which was similar (12.3 ± 7.4° vs. 13.4 ± 7.7°, p = NS). Basal and apical CS and basal rotation impair during exercise-induced ischemia. LV-Tor decreases with ischemia due to worsening of basal rotation, whereas apical rotation does not impair, suggesting the existence of an apical compensatory mechanism.

Left ventricular twist mechanics in the context of normal physiology and cardiovascular disease: a review of studies using speckle tracking echocardiography

The anatomy of the adult human left ventricle (LV) is the result of its complex interaction with its environment. From the fetal to the neonatal to the adult form, the human LV undergoes an anatomical transformation that finally results in the most complex of the four cardiac chambers. In its adult form, the human LV consists of two muscular helixes that surround the midventricular circumferential layer of muscle fibers. Contraction of these endocardial and epicardial helixes results in a twisting motion that is thought to minimize the transmural stress of the LV muscle. In the healthy myocardium, the LV twist response to stimuli that alter preload, afterload, or contractility has been described and is deemed relatively consistent and predictable. Conversely, the LV twist response in patient populations appears to be a little more variable and less predictable, yet it has revealed important insight into the effect of cardiovascular disease on LV mechanical function. This review discusses important methodological aspects of assessing LV twist and evaluates the LV twist responses to the main physiological and pathophysiological states. It is concluded that correct assessment of LV twist mechanics holds significant potential to advance our understanding of LV function in human health and cardiovascular disease.

In vivo quantification of myocardial stiffness in hypertensive porcine hearts using MR elastography

PURPOSE

To determine alteration in left ventricular (LV) myocardial stiffness (MS) with hypertension (HTN). Cardiac MR elastography (MRE) was used to estimate MS in HTN induced pigs and MRE-derived MS measurements were compared against LV pressure, thickness and circumferential strain.

MATERIALS AND METHODS

Renal-wrapping surgery was performed to induce HTN in eight pigs. LV catheterization (to measure pressure) and cardiac MRI (1.5 Tesla; gradient echo-MRE and tagging) was performed pre-surgery at baseline (Bx), and post-surgery at month 1 (M1) and month 2 (M2). Images were analyzed to estimate LV-MS, thickness, and circumferential strain across the cardiac cycle. The associations between end-diastolic (ED) and end-systolic (ES) MS and (i) mean LV pressure; (ii) ED and ES thickness, respectively; and (iii) circumferential strain were evaluated using Spearman's correlation method.

RESULTS

From Bx to M2, mean pressure, MRE-derived stiffness, and thickness increased while circumferential strain decreased significantly (slope test, P ≤ 0.05). Both ED and ES MS had significant positive correlation with (i) mean pressure (ED MS: ρ = 0.56; P = 0.005 and ES MS: ρ = 0.45; P = 0.03); (ii) ED thickness ( ρ = 0.73; P < 0.0001) and ES thickness ( ρ = 0.84; P < 0.0001), respectively; but demonstrated a negative trend with circumferential strain (ED MS: ρ = 0.31 and ES MS: ρ = 0.37).

CONCLUSION

This study demonstrated that, in a HTN porcine model, MRE-derived MS increased with increase in pressure and thickness.

LEVEL OF EVIDENCE

1 J. Magn. Reson. Imaging 2017;45:813-820.

Uncontrolled blood pressure as an independent risk factor of early impaired left ventricular systolic function in treated hypertension

BACKGROUND

Uncontrolled blood pressure (BP) is commonly observed in patients receiving antihypertensive agents. However, its relationship with early left ventricular (LV) dysfunction has not been elucidated.

METHODS

This study enrolled 276 patients with treated hypertension and 85 healthy controls. The 140/90 mm Hg was used to define controlled (HT1 group, n=145) or uncontrolled BP (HT2 group, n=131) according to the concurrent guidelines. LV myocardial function was assessed by two-dimensional speckle tracking imaging, and the circumferential end-systolic wall stress (cESS)-corrected mid-wall fraction shortening (MWFS), systolic longitudinal (εLs-18), circumferential (εCs-18), and radial (εRs-18) strain were measured.

RESULTS

Despite similar ejection fraction, the HT1 and HT2 groups displayed an overall reduction in the cESS-corrected MWFS (13.4±2.7 vs 11.7±1.7 vs 15.5±1.2), εLs-18 (15.6±2.8 vs 13.0±2.2 vs 17.4±2.8), εCs-18 (17.3±3.4 vs 14.1±2.7 vs 18.9±3.3), and εRs-18 (18.4±4.0 vs 14.8±3.1 vs 20.5±4.5) %·cm² /kdyne·10^-2 when compared with the control group (all P<.001). The changes were more obvious in the HT2 group, regardless of LV hypertrophy. Reductions in the cESS-corrected MWFS and εLs-18 were seen in 68 (25%) and 52 (19%) patients, respectively. Uncontrolled BP were 4.365 times (95% CI 2.203-8.648, P<.001) and 3.928 times (1.851-8.337, P<.001) more likely to be associated with the changes.

CONCLUSIONS

Uncontrolled BP in hypertensive patients is associated with further reduction in LV myocardial function detected by advanced echocardiographic techniques, which cannot be explained by the increase in afterload. It might be regarded as a composite risk factor for earlier and faster development of clinical heart failure, therefore, a simplified treatment target.

A graph theoretic approach for computing 3D+time biventricular cardiac strain from tagged MRI data

Tagged magnetic resonance imaging (tMRI) is a well-established method for evaluating regional mechanical function of the heart. Many techniques have been developed to compute 2D or 3D cardiac deformation and strain from tMRI images. In this paper, we present a new method for measuring 3D plus time biventricular myocardial strain from tMRI data. The method is composed of two parts. First, we use a Gabor filter bank to extract tag points along tag lines. Second, each tag point is classified to one of a set of indexed reference tag lines using a point classification with graph cuts (PCGC) algorithm and a motion compensation technique. 3D biventricular deformation and strain is computed at each image time frame from the classified tag points using a previously published finite difference method. The strain computation is fully automatic after myocardial contours are defined near end-diastole and end-systole. An in-vivo dataset composed of 30 human imaging studies with a range of pathologies was used for validation. Strains computed with the PCGC method with no manual corrections were compared to strains computed from both manually placed tag points and a manually-corrected unwrapped phase method. A typical cardiac imaging study with 10 short-axis slices and 6 long-axis slices required 30 min for contouring followed by 44 min of automated processing. The results demonstrate that the proposed method can reconstruct accurate 3D plus time cardiac strain maps with minimal user intervention.

Improved Right Ventricular Performance with Increased Tricuspid Annular Excursion in Athlete's Heart

Background

Marathon runners (MTH) and patients with mitral regurgitation (MR) exhibit left ventricular (LV) overload, and LV geometric changes in these groups have been reported. In this study, right ventricular (RV) adaptation to chronic volume overload was evaluated in MTH and MR and normal controls together with interventricular septal remodeling and tricuspid annulus (TA) motion.

Methods

A total of 60 age-matched subjects (including 19 MTH, 17 isolated chronic compensated MR patients, and 24 normal subjects) underwent conventional cine and tagged cardiac magnetic resonance imaging. Myocardial strain and curvature were computed on the interventricular septum and RV free wall. A dual-propagation technique was applied to construct RV volume-time curves for a single cardiac cycle. Similarly, the TA was tracked throughout the cardiac cycle to create displacement over time curve.

Results

Septal curvature was significantly lower in MTH and MR compared to controls. No significant differences in RV free-wall strain or RV ejection fraction were noted among the three groups. However, longitudinal TA excursion was significantly higher in MTH compared to controls (p = 0.0061). The peak late diastolic TA velocity in MR was significantly faster than MTH (p = 0.0031) and controls (p = 0.020).

Conclusion

Increased TA kinetics allows for improved RV performance in MTH. Septal remodeling was observed in both MR and MTH, therefore a direct relationship of septal remodeling to TA kinetics in athlete’s heart could not be elucidated in this study.

Regional Heterogeneity in 3D Myocardial Shortening in Hypertensive Left Ventricular Hypertrophy: A Cardiovascular CMR Tagging Substudy to the Life Study

BACKGROUND

Increased relative wall thickness in hypertensive left ventricular hypertrophy (LVH) has been shown by echocardiography to allow preserved shortening at the endocardium despite depressed LV midwall circumferential shortening (MWCS). Depressed MWCS is an adverse prognostic indicator, but whether this finding reflects reduced global or regional LV myocardial function, as assessed by three-dimensional (3D) myocardial strain, is unknown.

METHODS AND RESULTS

Cardiac Magnetic Resonance (CMR) tissue tagging permits direct evaluation of regional 3D intramyocardial strain, independent of LV geometry. We evaluated 21 hypertensive patients with electrocardiographic LVH in the LIFE study and 8 normal controls using 3D MR tagging and echocardiography. Patients had higher MR LV mass than normals (116 ± 40 versus 63 ± 6 g/m2, P = 0.002). Neither echocardiographic fractional shortening (32 ± 6 versus 33% ± 3%), LVEF (63% versus 64%) or mean end-systolic stress (175 ± 27 versus 146 ± 28 g/cm2) were significantly different, yet global MWCS was decreased by both echocardiography (13.4 ± 2.8 versus 18.2% ± 1.5%, P < 0.001) and MR (16.8 ± 3.6 versus 21.6% ± 3.0%, P < 0.005). 3D MR MWCS was lower at the base versus apex (P = 0.002) in LVH and greater in lateral and anterior regions versus septal and posterior regions (P < 0.001), contributing to the higher mean global MWCS by MR than echo. MR longitudinal strain was severely depressed in LVH patients (11.0 ± 3.3 versus 16.5% ± 2.5%, P < 0.001) and apical twist was increased (17.5 ± 4.3 versus 13.7 ± 3.7, P < 0.05). Importantly, both circumferential and longitudinal shortening correlated with LV relative wall thickness (R > 0.60, P = 0.001 for both).

CONCLUSIONS

In patients with hypertensive LVH, despite normal LV function via echocardiography or CMR, CMR intramyocardial tagging show depressed global MWCS while 3D MR strain revealed marked underlying regional heterogeneity of LV dysfunction.

Regional myocardial functional patterns: Quantitative tagged magnetic resonance imaging in an adult population free of cardiovascular risk factors: The multi-ethnic study of atherosclerosis (MESA)

PURPOSE

To characterize the left ventricular (LV) regional deformation patterns and identify normal values of left ventricular strains from tagged magnetic resonance imaging (MRI) in a population with low-risk-factor (LRF) exposure.

MATERIALS AND METHODS

Tagged CMR on three LV short axis slices was performed in participants of the MESA study who were free of cardiovascular disease at baseline. Images were analyzed by the harmonic phase imaging method to obtain: peak torsion, circumferential (Ecc) and radial (Err) strains, and systolic (SRs) and early-diastolic (SRe) strain rates. An LRF group was created from the overall population based on strict exclusion criteria (n = 129) based on risk factors and events observed over a 10-year follow-up.

RESULTS

The normative prediction intervals for the averaged peak Ecc (%) and torsion (deg/cm) measures were: in 45-59-year-old women: (-20.8, -13.2) and (2.1, 6.3); 60-84-year-old women: (-20.6, -12.8) and (2.2, 6.9); 45-59-year-old men: (-21.3, -13.5) and (1.9, 5.7); 60-84-year-old men: (-20.5, -12.5) and (1.5, 5.2). In general, African-Americans (Ecc = -15.9, torsion = 3.3) had lower strains as compared to Chinese (Ecc = -17.1, torsion = 3.9), while Caucasians and Hispanics were intermediate and not significantly different. Circumferential shortening increased spatially from the epicardium to the endocardium (-16.9 to -18.2 at the mid-ventricle) and from the base to the apex (-15.1 to -17.5 at the midwall).

CONCLUSION

The present study provides reference ranges and deformation patterns of deformation values from a large healthy population free of cardiovascular disease at baseline.

The microvascular effects of insulin resistance and diabetes on cardiac structure, function, and perfusion: a cardiovascular magnetic resonance study

Aims

Type 2 diabetes mellitus is an independent risk factor for the development of heart failure. To better understand the mechanism by which this occurs, we investigated cardiac structure, function, and perfusion in patients with and without diabetes.

Methods and results

Sixty-five patients with no stenosis >30% on invasive coronary angiography were categorized into diabetes (19) and non-diabetes (46) which was further categorized into prediabetes (30) and controls (16) according to the American Diabetes Association guidelines. Each patient underwent comprehensive cardiovascular magnetic resonance assessment. Left-ventricular (LV) mass, relative wall mass (RWM), Lagrangian circumferential strain, LV torsion, and myocardial perfusion reserve (MPR) were calculated. LV mass was higher in diabetics than non-diabetics (112.8 ± 39.7 vs. 91.5 ± 21.3 g, P = 0.01) and in diabetics than prediabetics (112.8 ± 39.7 vs. 90.3 ± 18.7 g, P = 0.02). LV torsion angle was higher in diabetics than non-diabetics (9.65 ± 1.90 vs. 8.59 ± 1.91°, P = 0.047), and MPR was lower in diabetics than non-diabetics (2.10 ± 0.76 vs. 2.84 ± 1.25 mL/g/min, P = 0.01). There was significant correlation between MPR and early diastolic strain rate (r = −0.310, P = 0.01) and LV torsion (r = −0.306, P = 0.01). In multivariable linear regression analysis, non-diabetics waist–hip ratio, but not body mass index, had a significant association with RWM (Beta = 0.34, P = 0.02).

Conclusion

Patients with diabetes have increased LV mass, LV torsion, and decreased MPR. There is a significant association between decreased MPR and increased LV torsion suggesting a possible mechanistic link between microvascular disease and cardiac dysfunction in diabetes.

Left ventricular twist and ventricular-arterial coupling in hypertensive patients

BACKGROUND

Left ventricular (LV) twist is usually influenced by LV hypertrophy resulting from hypertension or vascular stiffness. Vascular stiffness would increase arterial elastance (Ea), whereas LV end-systolic stiffness (Ees) could be influenced by LV hypertrophy. Therefore, in hypertensive patients, we assessed the extent to which ventricular-arterial coupling (VAC; Ea/Ees) affects LV twist, which may be a compensatory mechanism for systolic dysfunction.

METHODS

Hypertensive patients (n = 128) and healthy controls (n = 40) underwent conventional and speckle tracking echocardiography including LV twist. Ea and Ees were estimated noninvasively by echocardiography. Patients were divided into 3 tertiles according to the twist angle. Univariate and multivariate regression analyses were performed to test the influence of VAC on twist.

RESULTS

Patients in the lowest LV twist tertile had larger LV end-systolic volume, lower ejection fraction, lesser mid-wall fractional shortening (MWFS), and higher LV mass index (LVMI), compared to those with the highest tertile. They showed the lower septal tissue Doppler velocity, and global longitudinal and circumferential strain. With regard to VAC, Ea was similar among 3 groups, but Ees was significantly decreased in patient with lower tertile, resulting in increased VAC (1.1 ± 0.2 vs. 0.9 ± 0.1 vs. 0.7 ± 0.1, P < 0.001). While LV twist showed significant correlations with Ees, MWFS, and LVMI, VAC (β = -14.92, P < 0.001) was most associated with twist in a multivariate analysis.

CONCLUSIONS

LV twist was significantly associated with VAC in accordance with LV function; LV twist and VAC decreased progressively as LV systolic function deteriorated, while being enhanced during the well-compensated phase.

Effect of renal denervation on left ventricular mass and function in patients with resistant hypertension: data from a multi-centre cardiovascular magnetic resonance imaging trial

AIMS

Sympathetic stimulation induces left ventricular hypertrophy and is associated with increased cardiovascular risk. Catheter-based renal denervation (RDN) has been shown to reduce sympathetic outflow and blood pressure (BP). The present multi-centre study aimed to investigate the effect of RDN on anatomic and functional myocardial parameters, assessed by cardiac magnetic resonance (CMR), in patients with resistant hypertension.

METHODS AND RESULTS

Cardiac magnetic resonance was performed in 72 patients (mean age 66 ± 10 years) with resistant hypertension (55 patients underwent RDN, 17 served as controls) at baseline and after 6 months. Clinical data and CMR results were analysed blindly. Renal denervation significantly reduced systolic and diastolic BP by 22/8 mm Hg and left ventricular mass index (LVMI) by 7.1% (46.3 ± 13.6 g/m(1.7) vs. 43.0 ± 12.6 g/m(1.7), P < 0.001) without changes in the control group (41.9 ± 10.8 g/m(1.7) vs. 42.0 ± 9.7 g/m(1.7), P = 0.653). Ejection fraction (LVEF) in patients with impaired LVEF at baseline (<50%) significantly increased after RDN (43% vs. 50%, P < 0.001). Left ventricular circumferential strain as a surrogate of diastolic function in the subgroup of patients with reduced strain at baseline increased by 21% only in the RDN group (-14.8 vs. -17.9; P = 0.001) and not in control patients (-15.5 vs. -16.4, P = 0.508).

CONCLUSIONS

Catheter-based RDN significantly reduced BP and LVMI and improved EF and circumferential strain in patients with resistant hypertension, occurring partly BP independently.

Two- and three-dimensional speckle tracking analysis of the relation between myocardial deformation and functional capacity in patients with systemic hypertension

The purpose of this study was to investigate left ventricular (LV) mechanics in hypertensive patients by 2- and 3-dimensional (3D) speckle tracking imaging, and determine the relation between the LV mechanics and functional capacity in this population. This cross-sectional study included 51 recently diagnosed, untreated, hypertensive patients, 49 treated subjects with well-controlled arterial hypertension, 52 treated participants with uncontrolled hypertension, and 50 controls adjusted by gender and age. All the subjects underwent 24-hour blood pressure monitoring, complete 2-dimensional and 3D examination, and cardiopulmonary exercise testing. 3D global longitudinal, circumferential, radial, and area strains were similar between the control group and well-controlled hypertensive patients but significantly decreased in comparison with patients with untreated or inadequately controlled hypertension. Similar findings were obtained for LV torsion and twist rate, whereas LV untwisting rate significantly deteriorated from the controls, across the well-controlled group, to the patients with untreated or uncontrolled hypertension. Peak oxygen uptake was significantly lower in the patients with untreated and uncontrolled hypertension than in the controls and the well-treated hypertensive patients. Peak oxygen uptake was independently associated with LV untwisting rate (β = 0.28, p = 0.03), 3D LV ejection fraction (β = 0.31, p = 0.024), and 3D global longitudinal strain (β = 0.26, p = 0.037) in the whole hypertensive population in our study. In conclusion, LV mechanics and functional capacity are significantly impaired in the patients with uncontrolled and untreated hypertension in comparison with the controls and the well-controlled hypertensive patients. Functional capacity is independently associated with 3D global longitudinal strain, LV untwisting rate, and 3D LV ejection fraction.

Different contribution of extent of myocardial injury to left ventricular systolic and diastolic function in early reperfused acute myocardial infarction

Background

We sought to investigate the influence of the extent of myocardial injury on left ventricular (LV) systolic and diastolic function in patients after reperfused acute myocardial infarction (AMI).

Methods

Thirty-eight reperfused AMI patients underwent cardiac magnetic resonance (CMR) imaging after percutaneous coronary revascularization. The extent of myocardial edema and scarring were assessed by T2 weighted imaging and late gadolinium enhancement (LGE) imaging, respectively. Within a day of CMR, echocardiography was done. Using 2D speckle tracking analysis, LV longitudinal, circumferential strain, and twist were measured.

Results

Extent of LGE were significantly correlated with LV systolic functional indices such as ejection fraction (r = -0.57, p < 0.001), regional wall motion score index (r = 0.52, p = 0.001), and global longitudinal strain (r = 0.56, p < 0.001). The diastolic functional indices significantly correlated with age (r = -0.64, p < 0.001), LV twist (r = -0.39, p = 0.02), average non-infarcted myocardial circumferential strain (r = -0.52, p = 0.001), and LV end-diastolic wall stress index (r = -0.47, p = 0.003 with e’) but not or weakly with extent of LGE. In multivariate analysis, age and non-infarcted myocardial circumferential strain independently correlated with diastolic functional indices rather than extent of injury.

Conclusions

In patients with timely reperfused AMI, not only extent of myocardial injury but also age and non-infarcted myocardial function were more significantly related to LV chamber diastolic function.

Cardiac Systolic Mechanics in Heart Failure with Preserved Ejection Fraction: New Insights and Controversies

Heart failure with preserved ejection fraction (HFpEF) is a cardinal and complex syndrome tightly linked to several co-morbidities, and is currently emerging as a new public health problem in the elderly population. However, despite aggressive intervention, patients with HFpEF typically have a poor prognosis. Part of the reason underlying this phenomenon can be attributed to the insufficiently understood pathophysiology behind this syndrome. Traditional echocardiography-derived parameters such as left ventricular (LV) ejection fraction (LVEF) may not be useful in characterizing such a clinical disorder, or in further identifying the subjects at risk, owing in part to its lack of power to disclose subclinical systolic dysfunction in such a clinical scenario. Herein, we briefly reviewed the clinical manifestations and risk factors of HFpEF, and further provided insights into the understanding of the ventricular architecture and cardiac mechanics underlying HFpEF by utilizing advanced cardiovascular imaging modalities, with a special focus on myocardial deformation.

KEY WORDS

Heart failure; Speckle tracking imaging; Strain.