Preload dependency of left ventricular torsion: the impact of normal saline infusion

Adaptation of Left Ventricular Twist Mechanics in Exercise-Trained Children Is Only Evident after the Adolescent Growth Spurt

BACKGROUND

The extent of structural cardiac remodeling in response to endurance training is maturity dependent. In adults, this structural adaptation is often associated with the adaptation of left ventricular (LV) twist mechanics. For example, an increase in LV twist often follows an expansion in end-diastolic volume, whereas a reduction in twist may follow a thickening of the LV walls. While structural cardiac remodeling has been shown to be more prominent post-peak height velocity (PHV), it remains to be determined how this maturation-dependent structural remodeling influences LV twist. Therefore, we aimed to (1) compare LV twist mechanics between trained and untrained children pre- and post-PHV and (2) investigate how LV structural variables relate to LV twist mechanics pre- and post-PHV.

METHODS

Left ventricular function and morphology were assessed (echocardiography) in endurance-trained and untrained boys (n = 38 and n = 28, respectively) and girls (n = 39 and n = 34, respectively). Participants were categorized as either pre- or post-PHV using maturity offset to estimate somatic maturation.

RESULTS

Pre-PHV, there were no differences in LV twist or torsion between trained and untrained boys (twist: P = .630; torsion: P = .382) or girls (twist: P = .502; torsion: P = .316), and LV twist mechanics were not related with any LV structural variables (P > .05). Post-PHV, LV twist was lower in trained versus untrained boys (P = .004), with torsion lower in trained groups, irrespective of sex (boys: P < .001; girls: P = .017). Moreover, LV torsion was inversely related to LV mass (boys: r = -0.55, P = .001; girls: r = -0.46, P = .003) and end-diastolic volume (boys: r = -0.64, P < .001; girls: r = -0.36, P = .025) in both sexes.

CONCLUSIONS

A difference in LV twist mechanics between endurance-trained and untrained cohorts is only apparent post-PHV, where structural and functional remodeling were related.

Congestion in heart failure: a circulating biomarker-based perspective. A review from the Biomarkers Working Group of the Heart Failure Association, European Society of Cardiology

Congestion is a cardinal sign of heart failure (HF). In the past, it was seen as a homogeneous epiphenomenon that identified patients with advanced HF. However, current evidence shows that congestion in HF varies in quantity and distribution. This updated view advocates for a congestive-driven classification of HF according to onset (acute vs. chronic), regional distribution (systemic vs. pulmonary), compartment of distribution (intravascular vs. extravascular), and clinical vs. subclinical. Thus, this review will focus on the utility of circulating biomarkers for assessing and managing the different fluid overload phenotypes. This discussion focused on the clinical utility of the natriuretic peptides, carbohydrate antigen 125 (also called mucin 16), bio-adrenomedullin and mid-regional pro-adrenomedullin, ST2 (also known as interleukin-1 receptor-like 1), cluster of differentiation 146, troponin, C-terminal pro-endothelin-1, and parameters of haemoconcentration. The utility of circulation biomarkers on top of clinical evaluation, haemodynamics, and imaging needs to be better determined by dedicated studies. Some multiparametric frameworks in which these tools contribute to management are proposed.

A change of heart: Mechanisms of cardiac adaptation to acute and chronic hypoxia

Over the last 100 years, high-altitude researchers have amassed a comprehensive understanding of the global cardiac responses to acute, prolonged and lifelong hypoxia. When lowlanders are exposed to hypoxia, the drop in arterial oxygen content demands an increase in cardiac output, which is facilitated by an elevated heart rate at the same time as ventricular volumes are maintained. As exposure is prolonged, haemoconcentration restores arterial oxygen content, whereas left ventricular filling and stroke volume are lowered as a result of a combination of reduced blood volume and hypoxic pulmonary vasoconstriction. Populations native to high-altitude, such as the Sherpa in Asia, exhibit unique lifelong or generational adaptations to hypoxia. For example, they have smaller left ventricular volumes compared to lowlanders despite having larger total blood volume. More recent investigations have begun to explore the mechanisms underlying such adaptive responses by combining novel imaging techniques with interventions that manipulate cardiac preload, afterload, and/or contractility. This work has revealed the contributions and interactions of (i) plasma volume constriction; (ii) sympathoexcitation; and (iii) hypoxic pulmonary vasoconstriction with respect to altering cardiac loading, or otherwise preserving or enhancing biventricular systolic and diastolic function even amongst high altitude natives with excessive erythrocytosis. Despite these advances, various areas of investigation remain understudied, including potential sex-related differences in response to high altitude. Collectively, the available evidence supports the conclusion that the human heart successfully adapts to hypoxia over the short- and long-term, without signs of myocardial dysfunction in healthy humans, except in very rare cases of maladaptation.

A long duration race induces a decrease of left ventricular strains, twisting mechanics and myocardial work in trained adolescents

BACKGROUND

We investigated the acute cardiac consequences of a long-duration (>5 h) adventure race in adolescent athletes from evaluations of left ventricular (LV) strains and myocardial work.

METHODS

Twenty trained male adolescents (i.e. 8 ± 4 hours/week of endurance sports) aged 14 to 17 years participated in a competitive long-duration adventure race. Blood samples were collected before, immediately and 24 h after the race to determine the time course of troponin I (cTnI) considered as a myocardial damage biomarker. Resting echocardiography were conducted before and after the race to assess myocardial regional strains, LV twisting mechanics and myocardial work using speckle tracking echocardiography.

RESULTS

The mean completion time of the race was 05:38 ± 00:20 h, with a mean heart rate (HR) of 83 ± 5% of maximal HR. cTnI concentration significantly increased in 16/20 participants after the race (pre: 0.001 ± 0.002 vs. post: 0.244 ± 0.203 ng·dL^-1, p < 0.001) and returned to baseline within 24 h. Stroke volume, ejection fraction and global longitudinal strains remained unchanged after the race while LV twist and global myocardial work significantly decreased (8.6 ± 3.3 vs. 6.3 ± 3.3 deg and 2080 ± 250 vs. 1781 ± 334 mmHg%, p < 0.05). Diastolic function, indexes of myocardial relaxation and LV untwisting rate (-91.0 ± 19.0 vs. -56.4 ± 29.1 deg·s^-1, p < 0.001) were affected after the race.

CONCLUSION

We demonstrated for the first time that, in trained adolescents, a high-intensity endurance exercise of several hours induced an increase of the cTnI concentration associated with an alteration of myocardial function.

Key role of left ventricular untwisting in endurance cyclists at onset of exercise

The rise in oxygen consumption during the transition from rest to exercise is faster in those who are endurance-trained than those who have sedentary lifestyles, partly due to a more efficient cardiac response. However, data regarding this acute cardiac response in trained individuals are limited to heart rate (HR), stroke volume, and cardiac output. Considering this, we compared cardiac kinetics, including left ventricular (LV) strains and twist/untwist mechanics, between endurance-trained cyclists and their sedentary counterparts. Twenty young, male, trained cyclists and 23 untrained participants aged 18-25 yr performed five similar constant workload exercises on a cyclo-ergometer (target HR: 130 beats/min). During each session, LV myocardial diastolic and systolic linear strains, as well as torsional mechanics, were assessed using speckle-tracking echocardiography. Cardiac function was evaluated every 15 s during the first minute and every 30 s thereafter, until 240 s. Stroke volume increased during the first 30-45 s in both groups but to a significantly greater extent in trained cyclists (31% vs. 24%). Systolic parameters were similar in both groups. Transmitral peak filling velocity and peak filling rate responded faster to exercise and with greater amplitude in trained cyclists. Left ventricular filling pressure was lower in the former, whereas LV relaxation was greater but only at the base of the left ventricle. Basal rotation and peak untwisting rate responded faster and to a greater extent in the cyclists. This study provides new mechanical insights into the key role of LV untwisting in the more efficient acute cardiac response of endurance-trained athletes at onset of exercise.NEW & NOTEWORTHY Our study assessed for the first time, to our knowledge, the kinetics of left ventricular function during the transition from rest to constant-load exercise in endurance-trained subjects. We observed a faster cardiac response in cyclists characterized by a faster response of cardiac output, left ventricular transmitral filling, basal rotation, and untwisting. This study highlighted the key role of left ventricular twisting mechanics in the more efficient acute cardiac response of endurance-trained athletes at onset of exercise.

Pivotal Role of Heart for Orthostasis: Left Ventricular Untwisting Mechanics and Physical Fitness

Augmentation of left ventricular (LV) untwisting due to central hypovolemia is likely to be a compensatory mechanism for maintaining stroke volume, which is reduced by a decrease in cardiac filling during orthostatic stress. Orthostatic intolerance observed in both high and low fitness levels may be explained by the impaired response of LV untwisting due to central hypovolemia.

Right Ventricular Failure Post-Implantation of Left Ventricular Assist Device: Prevalence, Pathophysiology, and Predictors

Despite advances in left ventricular assist device (LVAD) technology, right ventricular failure (RVF) continues to be a complication after implantation. Most patients undergoing LVAD implantation have underlying right ventricular (RV) dysfunction (either as a result of prolonged LV failure or systemic disorders) that becomes decompensated post-implantation. Additional insults include intra-operative factors or a sudden increase in preload in the setting of increased cardiac output. The current literature estimates post-LVAD RVF from 3.9% to 53% using a diverse set of definitions. A few of the risk factors that have been identified include markers of cardiogenic shock (e.g., dependence on inotropes and Interagency Registry for Mechanically Assisted Circulatory Support profiles) as well as evidence of cardiorenal or cardiohepatic syndromes. Several studies have devised multivariable risk scores; however, their performance has been limited. A new functional assessment of RVF and a novel hepatic marker that describe cholestatic properties of congestive hepatopathy may provide additional predictive value. Furthermore, future studies can help better understand the relationship between pulmonary hypertension and post-LVAD RVF. To achieve our ultimate goal-to prevent and effectively manage RVF post-LVAD-we must start with a better understanding of the risk factors and pathophysiology. Future research on the different etiologies of RVF-ranging from acute post-surgical complication to late-onset RV cardiomyopathy-will help standardize definitions and tailor therapies appropriately.

The impact of lower body compression garment on left ventricular rotational mechanics in patients with lipedema-Insights from the three-dimensional speckle tracking echocardiographic MAGYAR-Path Study

Lipedema is a lymphedema-masquerading symmetrical, bilateral and disproportional obesity. Its conservative maintenance treatment comprises the use of flat-knitted compression pantyhoses. Lipedema is known to be associated with left ventricular morphological and functional alterations. The present study aimed to assess the effects of graduated compression stockings on left ventricular (LV) rotational mechanics measured by three-dimensional speckle-tracking echocardiography (3DSTE) in lipedema patients. The present study comprised twenty lipedema patients (mean age: 45.8 ± 11.0 years, all females) undergoing 3DSTE who were also compared to 51 age- and gender-matched healthy controls (mean age: 39.8 ± 14.1 years, all females). 3DSTE analysis was performed at rest, and subsequent to 1 hour application of compression class 2 made-to-measure flat-knitted pantyhose. Six lipedema patients showed significant LV rotational abnormalities. Of the remaining fourteen lipedema patients LV basal rotation rotation showed significant reduction, while LV apical rotation showed significant increase with unchanged LV twist after a 60-minute use of compression garment. Significant changes in LV rotational mechanics could be detected among 14 women with lipedema after the use of compression garment however six probands have special LV rotational abnormalities at baseline and/or after compression.

Effect of left ventricular assist device implantation on right ventricular function: Assessment based on right ventricular pressure-volume curves

Right ventricular (RV) failure is significantly associated with morbidity and mortality after left ventricular assist device (LVAD) implantation. However, it remains unclear whether LVAD implantation could worsen RV function. Therefore, we aimed to investigate the effect of LVAD implantation on RV function by comparing RV energetics derived from the RV pressure-volume curve between before and after LVAD implantation. This exploratory observational study was performed between September 2016 and January 2018 at a national center in Japan. Twenty-two patients who underwent LVAD implantation were included in the analysis. We measured RV energetics parameters: RV stroke work index (RVSWI), which was calculated by integrating the area within the RV pressure-volume curve; RV minute work index (RVMWI), which was calculated as RVSWI × heart rate; and right ventriculo-arterial coupling, which was estimated as RV stroke volume/RV end-systolic volume. We compared RV energetics between before and after LVAD implantation. Although RVSWI was similar [424.4 mm Hg · mL/m² (269.5-510.3) vs. 379.9 mm Hg · mL/m² (313.1-608.8), P = 0.485], RVMWI was significantly higher after LVAD implantation [29 834.1 mm Hg · mL/m² /min (18 272.2-36 357.1) vs. 38 544.8 mm Hg · mL/m² /min (29 016.0-57 282.8), P = 0.001], corresponding to a significantly higher cardiac index [2.0 L/min/m² (1.4-2.2) vs. 3.7 L/min/m² (3.3-4.1), P < 0.001] to match LVAD flow. Right ventriculo-arterial coupling was significantly higher after LVAD implantation [0.360 (0.224-0.506) vs. 0.480 (0.343-0.669), P = 0.025], suggesting that the efficiency of RV performance improved. In conclusion, higher RVMWI with higher cardiac index to match LVAD flow and improved efficiency of RV performance indicate that LVAD implantation might not worsen RV function.

Echocardiographic evidence of left ventricular untwisting-filling interplay

Background

Left ventricular untwisting generates an early diastolic intraventricular pressure gradient (DIVPG) than can be quantified by echocardiography. We sought to confirm the quantitative relationship between peak untwisting rate and peak DIVPG in a large adult population.

Methods

From our echocardiographic database, we retrieved all the echocardiograms with a normal left ventricular ejection fraction, for whom color Doppler M-Mode interrogation of mitral inflow was available, and left ventricular untwisting rate was measurable using speckle tracking. Standard indices of left ventricular early diastolic function were assessed by Doppler (peaks E, e’ and Vp) and speckle tracking (peak strain rate Esr). Load dependency of DIVPG and untwisting rate was evaluated using a passive leg raising maneuver.

Results

We included 154 subjects, aged between 18 to 77 years old, 63% were male. Test-retest reliability for color Doppler-derived DIVPG measurements was good, the intraclass correlation coefficients were 0.97 [0.91–0.99] and 0.97 [0.67–0.99] for intra- and inter-observer reproducibility, respectively. Peak DIVPG was positively correlated with peak untwisting rate (r = 0.73, P <  0.001). On multivariate analysis, peak DIVPG was the only diastolic parameter that was independently associated with untwisting rate. Age and gender were the clinical predictive factors for peak untwisting rate, whereas only age was independently associated with peak DIVPG. Untwisting rate and DIVPG were both load-dependent, without affecting their relationship.

Conclusions

Color Doppler-derived peak DIVPG was quantitatively and independently associated with peak untwisting rate. It thus provides a reliable flow-based index of early left ventricular diastolic function.

Superior cardiac mechanics without structural adaptations in pre-adolescent soccer players

AIMS

This study aimed to evaluate left ventricular structure, function and mechanics, in highly-trained, pre-adolescent soccer players compared with age- and sex-matched controls.

DESIGN

The study design was a prospective, cross-sectional comparison of left ventricular structure, function and mechanics.

METHODS

Twenty-two male soccer players from two professional youth soccer academies (age: 12.0 ± 0.3 years) and 22 recreationally active controls (age: 11.7 ± 0.3 years) were recruited. Two-dimensional conventional and speckle tracking echocardiography were used to quantify left ventricular structure, function and peak/temporal values for left ventricular strain and twist, respectively.

RESULTS

End-diastolic volume index was larger in soccer players (51 ± 8 mm/(m²)^1.5 vs. 45 ± 6 mm/(m²)^1.5; p = 0.007) and concentricity was lower in soccer players (4.3 ± 0.7 g/(mL)^0.667 vs. 4.9 ± 1.0 g/(mL)^0.667; p = 0.017), without differences in mean wall thickness between groups (6.0 ± 0.4 mm vs. 6.1 ± 0.5 mm; p = 0.754). Peak circumferential strain at the base (-22.2% ± 2.5% vs. -20.5% ± 2.5%; p = 0.029) and papillary muscle levels (-20.1% ± 1.5% vs. -18.3% ± 2.5%; p = 0.007) were greater in soccer players. Peak left ventricular twist was larger in soccer players (16.92° ± 7.55° vs. 12.34° ± 4.99°; p = 0.035) and longitudinal early diastolic strain rate was greater in soccer players (2.22 ± 0.40 s^-1 vs. 2.02 ± 0.46 s^-1; p = 0.025).

CONCLUSIONS

Highly-trained soccer players demonstrated augmented cardiac mechanics with greater circumferential strains, twist and faster diastolic lengthening in the absence of differences in wall thickness between soccer players and controls.

Unaltered left ventricular mechanics and remodelling after 12 weeks of resistance exercise training – a longitudinal study in men

Previous longitudinal studies suggest that left ventricular (LV) structure is unaltered with resistance exercise training (RT) in young men. However, evidence from aerobic exercise training suggests that early changes in functional LV wall mechanics may occur prior to and independently of changes in LV size, although short-term changes in LV mechanics and structural remodelling in response to RT protocols have not been reported. Therefore, the purpose of this study was to examine the effects of RT on LV mechanics in healthy men performing 2 different time-under-tension protocols. Forty recreationally trained men (age: 23 ± 3 years) were randomized into 12 weeks of whole-body higher-repetition RT (20–25 repetitions/set to failure at ∼30%–50% 1 repetition maximum (1RM); n = 13), lower-repetition RT (8–12 repetitions/set to failure at ∼75%–90% 1RM; n = 13), or an active control period (n = 14). Speckle tracking echocardiography was performed at baseline and following the intervention period. Neither RT program altered standard measures of LV volumes (end-diastolic volume, end-systolic volume, or ejection fraction; P > 0.05) or indices of LV mechanics (total LV twist, untwisting rate, twist-to-shortening ratio, untwisting-to-twist ratio, or longitudinal strain; P > 0.05). This is the first longitudinal study to assess both LV size and mechanics after RT in healthy men, suggesting a maintenance of LV size and twist mechanics despite peripheral muscle adaptations to the training programs. These results provide no evidence for adverse LV structural or functional remodelling in response to RT in young men and support the positive role of RT in the maintenance of optimal cardiovascular function, even with strenuous RT.

Efficacy of Exercise and Testosterone to Mitigate Atrophic Cardiovascular Remodeling

PURPOSE

Early and consistent evaluation of cardiac morphology and function throughout an atrophic stimulus is critically important for the design and optimization of interventions. This randomized controlled trial was designed 1) to characterize the time course of unloading-induced morphofunctional remodeling and 2) to examine the effects of exercise with and without low-dose testosterone supplementation on cardiac biomarker, structural, and functional parameters during unloading.

METHODS

Twenty-six subjects completed 70 d of head-down tilt bed rest (BR): 9 were randomized to exercise training (Ex), 8 to EX and low-dose testosterone (ExT), and 9 remained sedentary (CONT). Exercise consisted of high-intensity, continuous, and resistance exercise. Cardiac morphology (left ventricular mass [LVM]) and mechanics (longitudinal, radial, and circumferential strain and twist), cardiovascular biomarkers, and cardiorespiratory fitness (V˙O2peak) were assessed before, during, and after BR.

RESULTS

Sedentary BR resulted in a progressive decline in LVM, longitudinal, radial, and circumferential strain in CONT, whereas Ex and ExT mitigated decreases in LVM and function. Twist was increased throughout BR in sedentary BR, whereas after an initial increase at BR7, there were no further changes in twist in Ex and ExT. HDL cholesterol was significantly decreased in all groups compared with pre-BR (P < 0.007). There were no significant changes in other cardiovascular biomarkers. Change in twist was significantly related to change in V˙O2max (R = 0.68, P < 0.01).

CONCLUSION

An integrated approach with evaluation of cardiac morphology, mechanics, V˙O2peak, and biomarkers provides extensive phenotyping of cardiovascular atrophic remodeling. Exercise training and exercise training with low-dose testosterone supplementation abrogates atrophic remodeling.

Left Ventricular Speckle Tracking-Derived Cardiac Strain and Cardiac Twist Mechanics in Athletes: A Systematic Review and Meta-Analysis of Controlled Studies

Background

The athlete’s heart is associated with physiological remodeling as a consequence of repetitive cardiac loading. The effect of exercise training on left ventricular (LV) cardiac strain and twist mechanics are equivocal, and no meta-analysis has been conducted to date.

Objective

The objective of this systematic review and meta-analysis was to review the literature pertaining to the effect of different forms of athletic training on cardiac strain and twist mechanics and determine the influence of traditional and contemporary sporting classifications on cardiac strain and twist mechanics.

Methods

We searched PubMed/MEDLINE, Web of Science, and ScienceDirect for controlled studies of aged-matched male participants aged 18–45 years that used two-dimensional (2D) speckle tracking with a defined athlete sporting discipline and a control group not engaged in training programs. Data were extracted independently by two reviewers. Random-effects meta-analyses, subgroup analyses, and meta-regressions were conducted.

Results

Our review included 13 studies with 945 participants (controls n = 355; athletes n = 590). Meta-analyses showed no athlete–control differences in LV strain or twist mechanics. However, moderator analyses showed greater LV twist in high-static low-dynamic athletes (d = –0.76, 95% confidence interval [CI] –1.32 to –0.20; p < 0.01) than in controls. Peak untwisting velocity (PUV) was greater in high-static low-dynamic athletes (d = –0.43, 95% CI –0.84 to –0.03; p < 0.05) but less than controls in high-static high-dynamic athletes (d = 0.79, 95% CI 0.002–1.58; p = 0.05). Elite endurance athletes had significantly less twist and apical rotation than controls (d = 0.68, 95% CI 0.19–1.16, p < 0.01; d = 0.64, 95% CI 0.27–1.00, p = 0.001, respectively) but no differences in basal rotation. Meta-regressions showed LV mass index was positively associated with global longitudinal (b = 0.01, 95% CI 0.002–0.02; p < 0.05), whereas systolic blood pressure was negatively associated with PUV (b = –0.06, 95% CI –0.13 to –0.001; p = 0.05).

Conclusion

Echocardiographic 2D speckle tracking can identify subtle physiological differences in adaptations to cardiac strain and twist mechanics between athletes and healthy controls. Differences in speckle tracking echocardiography-derived parameters can be identified using suitable sporting categorizations.

Left ventricular function and mechanics following prolonged endurance exercise: an update and meta-analysis with insights from novel techniques

Background

The cardiac consequences of undertaking endurance exercise are the topic of recent debate. The purpose of this review is to provide an update on a growing body of literature, focusing on left ventricular (LV) function following prolonged endurance exercise over 2 h in duration which have employed novel techniques, including myocardial speckle tracking, to provide a more comprehensive global and regional assessment of LV mechanics.

Methods

Prospective studies were filtered independently following a pre-set criteria, resulting in the inclusion of 27 studies in the analyses. A random-effects meta-analysis was used to determine the weighted mean difference and 95% confidence intervals (CI) of LV functional and mechanical data from pre-to-post-exercise. Narrative commentary was also provided where volume of available evidence precluded meta-analysis.

Results

A significant overall reduction in LV longitudinal strain (Ɛ) n = 22 (− 18 ± 1 to − 17 ± 1%; effect size (d) − 9: − 1 to − 0.5%), strain rate n = 10 (SR;d − 0.9: − 0.1.3 to − 0.5 l/s) and twistn = 5 (11.9 ± 2.2 to 8.7 ± 2.2°,d − 1: − 1.6 to − 0.3°) was observed following strenuous endurance exercise (range 120–1740 min) (P < 0.01). A smaller number of studies (n = 4) also reported a non-significant reduction in global circumferential and radial Ɛ (P > 0.05).

Conclusion

The meta-analysis and narrative commentary demonstrated that a reduction in LV function and mechanics is evident following prolonged endurance exercise. The mechanism(s) responsible for these changes are complex and likely multi-factorial in nature and may be linked to right and left ventricular interaction.

Influence of vagal control on sex-related differences in left ventricular mechanics and hemodynamics

Left ventricular (LV) twist mechanics differ between men and women during acute physiological stress, which may be partly mediated by sex differences in autonomic control. While men appear to have greater adrenergic control of LV twist, the potential contribution of vagal modulation to sex differences in LV twist remains unknown. Therefore, the present study examined the role of vagal control on sex differences in LV twist during graded lower body negative pressure (LBNP) and supine cycling. On two separate visits, LV mechanics were assessed using two-dimensional speckle-tracking echocardiography in 18 men (22 ± 2 yr) and 17 women (21 ± 4 yr) during -40- and -60-mmHg LBNP and 25% and 50% of peak supine cycling workload with and without glycopyrrolate (vagal blockade). LV twist was not different at baseline but was greater in women during -60 mmHg in both control (women: 16.0 ± 3.4° and men: 12.9 ± 2.3°, P = 0.004) and glycopyrrolate trials (women: 17.7 ± 5.9° and men: 13.9 ± 3.3°, P < 0.001) due to greater apical rotation during control (women: 11.9 ± 3.6° and men: 7.8 ± 1.5°, P < 0.001) and glycopyrrolate (women: 11.6 ± 4.9° and men: 7.1 ± 3.6°, P = 0.009). These sex differences in LV twist consistently coincided with a greater LV sphericity index (i.e., ellipsoid geometry) in women compared with men. In contrast, LV twist did not differ between the sexes during exercise with or without glycopyrrolate. In conclusion, women have augmented LV twist compared with men during large reductions to preload, even during vagal blockade. As such, differences in vagal control do not appear to contribute to sex differences in the LV twist responses to physiological stress, but they may be related to differences in ventricular geometry. NEW & NOTEWORTHY This is the first study to specifically examine the role of vagal autonomic control on sex-related differences in left ventricular (LV) mechanics. Contrary to our hypothesis, vagal control does not appear to primarily determine sex differences in LV mechanical or hemodynamic responses to acute physiological stress. Instead, differences in LV geometry may be a more important contributor to sex differences in LV mechanics.

Early modifications of cardiac function in preterm neonates using speckle tracking echocardiography

BACKGROUND AND AIMS

Preterm newborns undergo hemodynamic challenges in the postnatal period. The aim of this study was to investigate myocardial mechanics changes in the postnatal period in preterm infants using speckle tracking echocardiography (STE).

MATERIAL AND METHODS

Thirty-nine preterm infants ≤34 weeks' gestation underwent cardiac ultrasound evaluation during the first 96 hours of life. A repeated echocardiogram at 3 weeks of age was performed. Echocardiographic assessment involved left ventricular ejection fraction, mitral E/A ratio, S' and E' velocities, E/E' ratio, tricuspid annular plane systolic excursion (TAPSE), left atrium-to-aorta ratio, ductal diameter and ductal shunt pattern. Left ventricular longitudinal, circumferential and radial strain, apex-basal rotation and twist were measured from the apical 4-chamber and short-axis views using STE.

RESULTS

The mean gestational age was 30 ± 2.7 weeks with a mean birth weight of 1318 ± 485 g. Apical segments demonstrated higher longitudinal strain than basal and mid-ones. In all gestational ages, endocardial longitudinal strain was higher than the epicardial. Epicardial longitudinal strain significantly increased during the first 3 weeks, resulting in the change in basal rotation from counterclockwise to clockwise and thus in the acquisition of twist. Deformation parameters were higher in infants with a hemodynamic significant patents ductus arteriosus.

CONCLUSIONS

Echocardiographic assessment of myocardial deformation parameters is feasible in preterm infants. Our data suggest that the maturational process of the myocardium is due to the development of the epicardial layer after birth, which allows the acquisition of the twist.

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.

Cardiac structure and function in elite Native Hawaiian and Pacific Islander Rugby Football League athletes: an exploratory study

The aim of this exploratory study was to define the Athletes Heart (AH) phenotype in Native Hawaiian & Pacific Islander (NH&PI) Rugby Football League (RFL) athletes. Specifically, (1) to describe conventional echocardiographic indices of left ventricle (LV) and right ventricle (RV) structure and function in NH&PI RFL players and matched RFL Caucasian controls (CC) and (2) to demonstrate LV and RV mechanics in these populations. Ethnicity is a contributory factor to the phenotypical expression of the AH. There are no data describing the cardiac phenotype in NH&PI athletes. Twenty-one male elite NH&PI RFL athletes were evaluated using conventional echocardiography and myocardial speckle tracking, allowing the assessment of global longitudinal strain (ε) and strain rate (SR); and basal, mid and global radial and circumferential ε and SR. Basal and apical rotation and twist were also assessed. Results were compared with age-matched Caucasian counterparts (CC; n = 21). LV mass [42 ± 9 versus 37 ± 4 g/(m^2.7)], mean LV wall thickness (MWT: 9.5 ± 0.7 and 8.7 ± 0.4 mm), relative wall thickness (RWT: 0.35 ± 0.04 and 0.31 ± 0.03) and RV wall thickness (5 ± 1 and 4 ± 1 mm, all p < 0.05) were greater in NH&PI compared with CC. LV and RV cavity dimensions and standard indices of LV and RV systolic and diastolic function were similar between groups. NH&PI demonstrated reduced peak LV mid circumferential ε and early diastolic SR, as well as reduced global radial ε. There was reduced basal rotation at 25–35% systole, reduced apical rotation at 25–40% and 60–100% systole and reduced twist at 85–95% systole in NH&PI athletes. There were no differences between the two groups in RV wall mechanics. When compared to Caucasian controls, NH&PI rugby players have a greater LV mass, MWT and RWT with concomitant reductions in circumferential and twist mechanics. This data acts to prompt further research in NH&PI athletes.

The impact of preload on 3-dimensional deformation parameters: principal strain, twist and torsion

Background

Strain analysis is feasible using three-dimensional (3D) echocardiography. This approach provides various parameters based on speckle tracking analysis from one full-volume image of the left ventricle; however, evidence for its volume independence is still lacking.

Methods

Fifty-eight subjects who were examined by transthoracic echocardiography immediately before and after hemodialysis (HD) were enrolled. Real-time full-volume 3D echocardiographic images were acquired and analyzed using dedicated software. Two-dimensional (2D) longitudinal strain (LS) was also measured for comparison with 3D strain values.

Results

Longitudinal (pre-HD: −24.57 ± 2.51, post-HD: −21.42 ± 2.15, P < 0.001); circumferential (pre-HD: −33.35 ± 3.50, post-HD: −30.90 ± 3.22, P < 0.001); and radial strain (pre-HD: 46.47 ± 4.27, post-HD: 42.90 ± 3.61, P < 0.001) values were significantly decreased after HD. The values of 3D principal strain (PS), a unique parameter of 3D images, were affected by acute preload changes (pre-HD: −38.10 ± 3.71, post-HD: −35.33 ± 3.22, P < 0.001). Twist and torsion values were decreased after HD (pre-HD: 17.69 ± 7.80, post-HD: 13.34 ± 6.92, P < 0.001; and pre-HD: 2.04 ± 0.86, post-HD:1.59 ± 0.80, respectively, P < 0.001). The 2D LS values correlated with the 3D LS and PS values.

Conclusion

Various parameters representing left ventricular mechanics were easily acquired from 3D echocardiographic images; however, like conventional parameters, they were affected by acute preload changes. Therefore, strain values from 3D echocardiography should be interpreted with caution while considering the preload conditions of the patients.

The influence of adrenergic stimulation on sex differences in left ventricular twist mechanics

KEY POINTS

Sex differences in left ventricular (LV) mechanics occur during acute physiological challenges; however, it is unknown whether sex differences in LV mechanics are fundamentally regulated by differences in adrenergic control. Using two-dimensional echocardiography and speckle tracking analysis, this study compared LV mechanics in males and females matched for LV length during post-exercise ischaemia (PEI) and β₁ -adrenergic receptor blockade. Our data demonstrate that while basal rotation was increased in males, LV twist was not significantly different between the sexes during PEI. In contrast, during β₁ -adrenergic receptor blockade, LV apical rotation, twist and untwisting velocity were reduced in males compared to females. Significant relationships were observed between LV twist and LV internal diameter and sphericity index in females, but not males. These findings suggest that LV twist mechanics may be more sensitive to alterations in adrenergic stimulation in males, but more highly influenced by ventricular structure and geometry in females.

ABSTRACT

Sex differences in left ventricular (LV) mechanics exist at rest and during acute physiological stress. Differences in cardiac autonomic and adrenergic control may contribute to sex differences in LV mechanics and LV haemodynamics. Accordingly, this study aimed to investigate sex differences in LV mechanics with altered adrenergic stimulation achieved through post-handgrip-exercise ischaemia (PEI) and β₁ -adrenergic receptor (AR) blockade. Twenty males (23 ± 5 years) and 20 females (22 ± 3 years) were specifically matched for LV length (males: 8.5 ± 0.5 cm, females: 8.2 ± 0.6 cm, P = 0.163), and two-dimensional speckle-tracking echocardiography was used to assess LV structure and function at baseline, during PEI and following administration of 5 mg bisoprolol (β₁ -AR antagonist). During PEI, LV end-diastolic volume and stroke volume were increased in both groups (P < 0.001), as was end-systolic wall stress (P < 0.001). LV twist and apical rotation were not altered from baseline or different between the sexes; however, basal rotation increased in males (P = 0.035). During β₁ -AR blockade, LV volumes were unchanged but blood pressure and heart rate were reduced in both groups (P < 0.001). LV apical rotation (P = 0.036) and twist (P = 0.029) were reduced in males with β₁ -AR blockade but not females, resulting in lower apical rotation (males: 6.8 ± 2.1 deg, females: 8.8 ± 2.3 deg, P = 0.007) and twist (males: 8.6 ± 1.9 deg, females: 10.7 ± 2.8 deg, P = 0.008), and slower untwisting velocity (males: 68.2 ± 22.1 deg s^-1 , females: 82.0 ± 18.7 deg s^-1 , P = 0.046) compared to females. LV twist mechanics are reduced in males compared to females during reductions to adrenergic stimulation, providing preliminary evidence that LV twist mechanics may be more sensitive to adrenergic control in males than in females.

Myocardial relaxation is accelerated by fast stretch, not reduced afterload

Fast relaxation of cross-bridge generated force in the myocardium facilitates efficient diastolic function. Recently published research studying mechanisms that modulate the relaxation rate has focused on molecular factors. Mechanical factors have received less attention since the 1980s when seminal work established the theory that reducing afterload accelerates the relaxation rate. Clinical trials using afterload reducing drugs, partially based on this theory, have thus far failed to improve outcomes for patients with diastolic dysfunction. Therefore, we reevaluated the protocols that suggest reducing afterload accelerates the relaxation rate and identified that myocardial relengthening was a potential confounding factor. We hypothesized that the speed of myocardial relengthening at end systole (end systolic strain rate), and not afterload, modulates relaxation rate and tested this hypothesis using electrically-stimulated trabeculae from mice, rats, and humans. We used load-clamp techniques to vary afterload and end systolic strain rate independently. Our data show that the rate of relaxation increases monotonically with end systolic strain rate but is not altered by afterload. Computer simulations mimic this behavior and suggest that fast relengthening quickens relaxation by accelerating the detachment of cross-bridges. The relationship between relaxation rate and strain rate is novel and upends the prevailing theory that afterload modifies relaxation. In conclusion, myocardial relaxation is mechanically modified by the rate of stretch at end systole. The rate of myocardial relengthening at end systole may be a new diagnostic indicator or target for treatment of diastolic dysfunction.

Left ventricular twist mechanics during incremental cycling and knee extension exercise in healthy men

Purpose

The objective of the present study was to investigate left ventricular (LV) twist mechanics in response to incremental cycling and isometric knee extension exercises.

Methods

Twenty-six healthy male participants (age = 30.42 ± 6.17 years) were used to study peak twist mechanics at rest and during incremental semi-supine cycling at 30 and 60% work rate maximum (W_max) and during short duration (15 s contractions) isometric knee extension at 40 and 75% maximum voluntary contraction (MVC), using two-dimensional speckle tracking echocardiography.

Results

Data presented as mean ± standard deviation or median (interquartile range). LV twist increased from rest to 30% W_max (13.21° ± 4.63° to 20.04° ± 4.76°, p < 0.001) then remained unchanged. LV systolic and diastolic twisting velocities progressively increased with exercise intensity during cycling from rest to 60% W_max (twisting, 88.21° ± 20.51° to 209.05° ± 34.56° s⁻¹, p < 0.0001; untwisting, −93.90 (29.62)° to −267.31 (104.30)° s⁻¹, p < 0.0001). During the knee extension exercise, LV twist remained unchanged with progressive intensity (rest 13.40° ± 4.80° to 75% MVC 16.77° ± 5.54°, p > 0.05), whilst twisting velocity increased (rest 89.15° ± 21.77° s⁻¹ to 75% MVC 124.32° ± 34.89° s⁻¹, p < 0.01). Untwisting velocity remained unchanged from rest [−90.60 (27.19)° s⁻¹] to 40% MVC (p > 0.05) then increased from 40 to 75% MVC [−98.44 (43.54)° s⁻¹ to −138.42 (73.29)° s⁻¹, p < 0.01]. Apical rotations and rotational velocities were greater than basal during all conditions and intensities (all p < 0.01).

Conclusion

Cycling increased LV twist to 30% W_max which then remained unchanged thereafter, whereas twisting velocities showed further increases to greater intensities. A novel finding is that LV twist was unaffected by incremental knee extension, yet systolic and diastolic twisting velocities augmented with isometric exercise.

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.

Cardiac Imaging to Evaluate Left Ventricular Diastolic Function

Left ventricular diastolic dysfunction in clinical practice is generally diagnosed by imaging. Recognition of heart failure with preserved ejection fraction has increased interest in the detection and evaluation of this condition and prompted an improved understanding of the strengths and weaknesses of different imaging modalities for evaluating diastolic dysfunction. This review briefly provides the pathophysiological background for current clinical and experimental imaging parameters of diastolic dysfunction, discusses the merits of echocardiography relative to other imaging modalities in diagnosing and grading diastolic dysfunction, summarizes lessons from clinical trials that used parameters of diastolic function as an inclusion criterion or endpoint, and indicates current areas of research.

Females have greater left ventricular twist mechanics than males during acute reductions to preload

Compared to males, females have smaller left ventricular (LV) dimensions and volumes, higher ejection fractions (EF), and higher LV longitudinal and circumferential strain. LV twist mechanics determine ventricular function and are preload-dependent. Therefore, the sex differences in LV structure and myocardial function may result in different mechanics when preload is altered. This study investigated sex differences in LV mechanics during acute challenges to preload. With the use of conventional and speckle-tracking echocardiography, LV structure and function were assessed in 20 males (24 ± 6.2 yr) and 20 females (23 ± 3.1 yr) at baseline and during progressive levels of lower body negative pressure (LBNP). Fourteen participants (8 males, 6 females) were also assessed following a rapid infusion of saline. LV end-diastolic volume, end-systolic volume, stroke volume (SV), and EF were reduced in both groups during LBNP (P < 0.001). While males had greater absolute volumes (P < 0.001), there were no sex differences in allometrically scaled volumes at any stage. Sex differences were not detected at baseline in basal rotation, apical rotation, or twist. Apical rotation and twist increased in both groups (P < 0.001) with LBNP. At -60 mmHg, females had greater apical rotation (P = 0.009), twist (P = 0.008), and torsion (P = 0.002) and faster untwisting velocity (P = 0.02) than males. There were no differences in mechanics following saline infusion. Females have larger LV twist and a faster untwisting velocity than males during large reductions to preload, supporting that females have a greater reliance on LV twist mechanics to maintain SV during severe reductions to preload.

The Effects of Exercise Intensity vs. Metabolic State on the Variability and Magnitude of Left Ventricular Twist Mechanics during Exercise

Increased left ventricular (LV) twist and untwisting rate (LV twist mechanics) are essential responses of the heart to exercise. However, previously a large variability in LV twist mechanics during exercise has been observed, which complicates the interpretation of results. This study aimed to determine some of the physiological sources of variability in LV twist mechanics during exercise. Sixteen healthy males (age: 22 ± 4 years, V˙O_2peak: 45.5 ± 6.9 ml∙kg^-1∙min^-1, range of individual anaerobic threshold (IAT): 32–69% of V˙O_2peak) were assessed at rest and during exercise at: i) the same relative exercise intensity, 40%_peak, ii) at 2% above IAT, and, iii) at 40%_peak with hypoxia (40%_peak+HYP). LV volumes were not significantly different between exercise conditions (P > 0.05). However, the mean margin of error of LV twist was significantly lower (F_2,47 = 2.08, P < 0.05) during 40%peak compared with IAT (3.0 vs. 4.1 degrees). Despite the same workload and similar LV volumes, hypoxia increased LV twist and untwisting rate (P < 0.05), but the mean margin of error remained similar to that during 40%peak (3.2 degrees, P > 0.05). Overall, LV twist mechanics were linearly related to rate pressure product. During exercise, the intra-individual variability of LV twist mechanics is smaller at the same relative exercise intensity compared with IAT. However, the absolute magnitude (degrees) of LV twist mechanics appears to be associated with the prevailing rate pressure product. Exercise tests that evaluate LV twist mechanics should be standardised by relative exercise intensity and rate pressure product be taken into account when interpreting results.

Exercise-Induced Left Ventricular Remodeling Among Competitive Athletes

Background—

Contemporary understanding of exercise-induced cardiac remodeling is based on cross-sectional data and relatively short duration longitudinal studies. Temporal progression of exercise-induced cardiac remodeling remains incompletely understood.

Methods and Results—

A longitudinal repeated-measures study design using 2-dimensional and speckle-tracking echocardiography was used to examine acute augmentation phase (AAP; 90 days) and more extended chronic maintenance phase (39 months) left ventricular (LV) structural and functional adaptations to endurance exercise training among competitive male rowers (n=12; age 18.6±0.5 years). LV mass was within normal limits at baseline (93±9 g/m 2 ), increased after AAP (105±7 g/m 2 ; P =0.001), and further increased after chronic maintenance phase (113±10 g/m 2 ; P <0.001 for comparison to post-AAP). AAP LV hypertrophy was driven by LV dilation (ΔLV end-diastolic volume, 9±3 mL/m 2 ; P =0.004) with stable LV wall thickness (ΔLV wall thickness, 0.3±0.1 mm; P =0.63). In contrast, chronic maintenance phase LV hypertrophy was attributable to LV wall thickening (Δ LV wall thickness, 1.1±0.4 mm; P =0.004) with stable LV chamber volumes (ΔLV end-diastolic volume, 1±1 mL/m 2 ; P =0.48). Early diastolic peak tissue velocity increased during AAP (−11.7±1.9 versus −13.6±1.3 cm/s; P <0.001) and remained similarly increased after chronic maintenance phase.

Conclusions—

In a small sample of competitive endurance athletes, exercise-induced cardiac remodeling follows a phasic response with increases in LV chamber size, early diastolic function, and systolic twist in an acute augmentation phase of exercise training. This is followed by a chronic phase of adaptation characterized by increasing wall thickness and regression in LV twist. Training duration is a determinant of exercise-induced cardiac remodeling and has implications for the assessment of myocardial structure and function in athletes.

E/e' Ratio in Patients With Unexplained Dyspnea: Lack of Accuracy in Estimating Left Ventricular Filling Pressure

BACKGROUND

Elevated left ventricular filling pressure is a cardinal feature of heart failure with preserved ejection fraction. Mitral E/e' ratio has been proposed as a noninvasive measure of left ventricular filling pressure. We studied the accuracy of E/e' to estimate and track changes of left ventricular filling pressure in patients with unexplained dyspnea.

METHODS AND RESULTS

We performed supine and upright transthoracic echocardiography in 118 patients with unexplained dyspnea who underwent right heart catheterization. Supine E/e' ratio modestly but significantly correlated with supine pulmonary arterial wedge pressure (PAWP; r=0.36; P<0.001) and demonstrated poor agreement with PAWP values (Bland-Altman limits of agreement of -8.3 to 8.3 mm Hg; range, 6.5-21.2 mm Hg). Similarly, E/e' ratio cut off of 13 performed poorly in identifying patients with elevated left ventricular filling pressure (sensitivity 6%, specificity 90%). The receiver-operating characteristic area of E/e' was 0.65 (95% confidencce interval, 0.50-0.79). With change from the supine to upright position, PAWP decreased (-5±4 mm Hg; P<0.001) as did both E wave (-17±15 cm/s; P<0.001) and e' (-2.7±2.7 cm/s; P<0.001) velocities, whereas E/e' remained stable (+0.2±2.6; P=0.57). Positional change in PAWP correlated modestly with change in E-wave (r=0.37; P<0.001) velocity. There was no appreciable relationship between change in PAWP and change in average E/e' (r=-0.04; P=0.77) and in half the patients the change in PAWP and E/e' were directionally opposite.

CONCLUSIONS

In patients with unexplained dyspnea, E/e' ratio neither accurately estimates PAWP nor identifies patients with elevated PAWP consistent with heart failure with preserved ejection fraction. Positional changes in E/e' ratio do not reflect changes in PAWP.

Increased LV apical untwist during preload reduction in healthy humans: an echocardiographic speckle tracking study during lower body negative pressure

We sought to investigate the effect of reduced preload on left ventricle (LV) untwist and early diastolic filling in healthy individuals. Twelve healthy men, 22 (22, 23) years of age, were examined at rest and during applied lower body negative pressure (LBNP) of −20 mmHg and −40 mmHg, respectively. Regional untwist and untwist rate during IVRT were calculated at LV basal, papillary, subpapillary, and apical short axis levels by two dimensional speckle tracking echocardiography. Left ventricle early diastolic filling was assessed by transmitral E-wave (E) peak velocity by pulsed Doppler and flow propagation velocity (Vp) by color M-mode Doppler and early diastolic pulsed Doppler tissue velocities (E') from septal and lateral mitral annulus. From rest to LBNP −40 mmHg, the LV untwist and untwist rate at subpapillary level increased from 2.3 (1.4, 3.5) to 4.5 (3.1, 7.6) degrees and from −36 (−51, −25) to −69 (−127, −42) °/s (P < 0.001, P = 0.003), respectively, while apical untwist and untwist rate increased from 3.9 (2.3, 4.3) to 7.6 (6.4, 10.5) degrees and from −51 (−69, −40) to −118 (−170, −84) °/s (P < 0.001, P < 0.001), respectively. Since untwist and untwist rate at the basal level were unchanged, this created markedly larger base to apical untwist and untwist rate gradients from rest to LBNP −40 mmHg. E, Vp, and E' were reduced by 34, 32, and 39%, respectively. LV untwist and untwist rate during IVRT were increased at apical levels, which might be a physiological mechanism to minimize the impairment in LV early diastolic filling during preload reduction.

Left ventricular rotational mechanics in Tanzanian children with sickle cell disease

Background

Sickle cell disease (SCD) is a common inherited hemoglobinopathy. Adults with SCD manifest both systolic and diastolic cardiac dysfunction, though the age of onset of dysfunction has not been defined. Left ventricular (LV) rotational mechanics have not been studied in children with SCD. The aim of this study was to investigate whether cardiac rotational mechanics differed between children with SCD and age-matched controls.

Methods

Basal and apical LV short-axis images were acquired prospectively in 213 patients with SCD (mean age, 14.1 ± 2.6 years) and 49 controls (mean age, 13.3 ± 2.8 years) from the Muhimbili Sickle Cohort in Dar es Salaam, Tanzania. The magnitude of basal and apical rotation, net twist angle, torsion, and untwist rate were obtained by two-dimensional speckle-tracking. The timing of events was normalized to aortic valve closure.

Results

Mean basal rotation was significantly lower in patients with SCD compared with controls (P = .012), although no difference was observed in apical rotation (P = .37). No statistically significant differences in torsion or net twist angle were detected. Rotation rate at the apex (P = .001) and base (P = .0004) were significantly slower in subjects with SCD compared with controls. Mean peak untwisting rate was also significantly slower in patients with SCD (P = .006). No associations were found between hemoglobin concentration and apical rotation, basal rotation, net twist, and torsion.

Conclusion

This study demonstrates alterations in LV rotational mechanics in children with SCD, including lower basal rotation, peak differential twist, and untwist rate. These abnormalities denote subclinical changes in LV systolic and diastolic performance in children with SCD. Future work may reveal an association between rotational metrics and long-term patient outcomes.

Left ventricular rotation and right-left ventricular interaction in congenital heart disease: the acute effects of interventional closure of patent arterial ducts and atrial septal defects

BACKGROUND

Left ventricular rotation is physiologically affected by acute changes in preload. We investigated the acute effect of preload changes in chronically underloaded and overloaded left ventricles in children with shunt lesions.

METHODS

A total of 15 patients with atrial septal defects (Group A: 7.4 ± 4.7 years, 11 females) and 14 patients with patent arterial ducts (Group B: 2.7 ± 3.1 years, 10 females) were investigated using 2D speckle-tracking echocardiography before and after interventional catheterisation. The rotational parameters of the patient group were compared with those of 29 matched healthy children (Group C).

RESULTS

Maximal torsion (A: 2.45 ± 0.9°/cm versus C: 1.8 ± 0.8°/cm, p < 0.05), apical peak systolic rotation (A: 12.6 ± 5.7° versus C: 8.7 ± 3.5°, p < 0.05), and the peak diastolic torsion rate (A: -147 ± 48°/second versus C: -110 ± 31°/second, p < 0.05) were elevated in Group A and dropped immediately to normal values after intervention (maximal torsion 1.5 ± 1.1°/cm, p < 0.05, apical peak systolic rotation 7.2 ± 4.1°, p < 0.05, and peak diastolic torsion rate -106 ± 35°/second, p < 0.05). Patients in Group B had decreased maximal torsion (B: 1.8 ± 1.1°/cm versus C: 3.8 ± 1.4°/cm, p < 0.05) and apical peak systolic rotation (B: 8.3 ± 6.1° versus C: 13.9 ± 4.3°, p < 0.05). Defect closure was followed by an increase in maximal torsion (B: 2.7 ± 1.4°/cm, p < 0.05) and the peak diastolic torsion rate (B: -133 ± 66°/second versus -176 ± 84°/second, p < 0.05).

CONCLUSIONS

Patients with chronically underloaded left ventricles compensate with an enhanced apical peak systolic rotation, maximal torsion, and quicker diastolic untwisting to facilitate diastolic filling. In patients with left ventricular dilatation by volume overload, the peak systolic apical rotation and the maximal torsion are decreased. After normalisation of the preload, they immediately return to normal and diastolic untwisting rebounds. These mechanisms are important for understanding the remodelling processes.

Left ventricular torsional mechanics and myocardial iron load in beta-thalassaemia major: a potential role of titin degradation

BACKGROUND

Iron may damage sarcomeric proteins through oxidative stress. We explored the left ventricular (LV) torsional mechanics in patients with beta-thalassaemia major and its relationship to myocardial iron load. Using HL-1 cell and B6D2F1 mouse models, we further determined the impact of iron load on proteolysis of the giant sarcomeric protein titin.

METHODS AND RESULTS

In 44 thalassaemia patients aged 25 ± 7 years and 38 healthy subjects, LV torsion and twisting velocities were determined at rest using speckle tracking echocardiography. Changes in LV torsional parameters during submaximal exercise testing were further assessed in 32 patients and 17 controls. Compared with controls, patients had significantly reduced LV apical rotation, torsion, systolic twisting velocity, and diastolic untwisting velocity. T2* cardiac magnetic resonance findings correlated with resting diastolic untwisting velocity. The increments from baseline and resultant LV torsion and systolic and diastolic untwisting velocities during exercise were significantly lower in patients than controls. Significant correlations existed between LV systolic torsion and diastolic untwisting velocities in patients and controls, both at rest and during exercise. In HL-1 cells and ventricular myocardium of B6D2F1 mice overloaded with iron, the titin-stained pattern of sarcomeric structure became disrupted. Gel electrophoresis of iron-overloaded mouse myocardial tissue further showed significant decrease in the amount of titin isoforms and increase in titin degradation products.

CONCLUSIONS

Resting and dynamic LV torsional mechanics is impaired in patients with beta-thalassaemia major. Cell and animal models suggest a potential role of titin degradation in iron overload-induced alteration of LV torsional mechanics.

Evaluation of left ventricular torsion in children with hypertrophic cardiomyopathy

AIMS

To evaluate the role of torsion in hypertrophic cardiomyopathy in children.

METHODS

A total of 88 children with idiopathic hypertrophic cardiomyopathy (n = 24) and concentric hypertrophy (n = 20) were investigated with speckle-tracking echocardiography and compared with age- and gender-matched healthy controls (n = 44).

RESULTS

In hypertrophic cardiomyopathy, we found increased torsion (2.8 ± 1.6 versus 1.9 ± 1.0°/cm [controls], p < 0.05) because of an increase in clockwise basal rotation (-8.7 ± 4.3° versus -4.9 ± 2.5° [controls], p < 0.001) and prolonged time to peak diastolic untwisting (3.7 ± 2.4% versus 1.7 ± 0.6% [controls] of cardiac cycle, p < 0.01), but no differences in peak untwisting velocities. Hypertrophic cardiomyopathy patients demonstrated a negative correlation between left ventricular muscle mass and torsion (r = -0.7, p < 0.001). In concentric hypertrophy, torsion was elevated because of increased apical rotation (15.1 ± 6.4° versus 10.5 ± 5.5° [controls], p < 0.05) without correlation with muscle mass. Peak untwisting velocities (- 202 ± 88 versus -145 ± 67°/s [controls], p < 0.05) were higher in concentric hypertrophy and time to peak diastolic untwisting was delayed (1.8 ± 0.8% versus 1.2 ± 0.6% [controls], p < 0.05).

CONCLUSIONS

In contrast to an increased counterclockwise apical rotation in concentric hypertrophy, hypertrophic cardiomyopathy is characterised by predominantly enhanced systolic basal clockwise rotation. Diastolic untwisting is delayed in both groups. Torsion may be an interesting marker to guide patients with hypertrophic cardiomyopathy.