End Systole Research Articles

Associations between Skeletal Muscle and Myocardium in Aging: A Syndrome of "Cardio-Sarcopenia"?

The link between skeletal muscle and heart disease remains intriguing. It is unknown how skeletal muscle may be associated with aspects of myocardial structure and function, particularly in the presence of aging-related sarcopenia. We hypothesize that among aging adults with sarcopenia, alterations in myocardial structure and/or function may exist, resulting in a syndrome of "cardio-sarcopenia." Participants derived from a community cohort study underwent same-day bioimpedance body composition analysis that measured skeletal muscle in sites such as the trunk, upper limb, and lower limb, and echocardiography for assessment of myocardial structure and function. Sarcopenia was diagnosed using the Asian Working Group for Sarcopenia criteria. We studied a total of 378 participants, of whom 88 (23.3%) had sarcopenia. Participants with sarcopenia had smaller left ventricular (LV) sizes (lower LV internal diameter end diastole (4.1 ± .7 vs 4.5 ± .6 cm; P < .0001), lower LV internal diameter end systole (2.3 ± .5 vs 2.5 ± .4 cm; P = .010), lower LV posterior wall end diastole (.7 ± .1 vs .8 ± .1 cm; P = .0036), and lower LV posterior wall end systole (1.4 ± .3 vs 1.5 ± .2 cm; P = .0031). Sarcopenic participants also had lower LV mass (106 ± 35 vs 126 ± 53; P = .0014) and lower left atrial (LA) volume (33 ± 13 vs 36 ± 13; P = .033). Adjusting for age and diabetes mellitus, skeletal muscle mass was associated with LV diameter (β = .06; 95% confidence interval [CI] = .03-.09; P < .0001), LV mass (β = 4.04; 95% CI = 1.78-6.29; P = .001), LA diameter (β = .05; 95% CI = .01-.09; P = .007), and LA volume (β = 1.26; 95% CI = .38-2.13; P = .005). A positive linear correlation was observed between LV mass and handgrip strength (r = .25; P < .0001). Among a community sample of older adults with preserved heart function, sarcopenia is associated with reductions in LV and LA sizes. Skeletal muscle mass was independently associated with specific indices of myocardial structure. J Am Geriatr Soc 67:2568-2573, 2019.

Abstract 614: Using Intact Trabeculae to Determine the Effect of Myosin-Modifying Drugs on Work, Power, and Mechanical Control of Relaxation

Background: Heart failure and especially heart failure with preserved ejection fraction are significant burdens on health. Intact cardiac trabeculae may reveal functional changes that cannot be seen in other ex vivo (skinned, single molecule) preparations. For example, using intact trabeculae, we have shown that relaxation is mechanically controlled by the lengthening strain rate at end systole, not afterload. Objective: We sought to evaluate the effect of myosin activator Omecamtiv Mercarbil (OM) and inhibitor Mavacamten (Mav) on physiologic function in intact trabeculae. Methods/Results: Afterload-clamp protocols were applied to intact cardiac trabeculae from Sprague Dawley rats to simulate physiologic work-loops and evaluate mechanical control of relaxation. Both OM and Mav reduced stroke work (force x length) by &gt;50% and power (force x velocity) by ~50% at doses reducing developed force by 50%. These were mediated by dose-dependent reductions in both force and shortening length. We have recently reported preliminary results that OM improves contraction-relaxation coupling and makes the relaxation rate more sensitive to strain rate in a dose-dependent manner. Mav does not lead to significant changes in contraction-relaxation coupling at any dose; Mav alters the sensitivity of relaxation rate to strain rate only at doses that reduce developed force by 50%. Summary/Perspective: Intact rat cardiac trabeculae reveal function mimicking physiology. OM and Mav show remarkable similarities in force, work, and power, which may be due to the high expression of alpha-myosin heavy chain. OM treatment not only modified contractility but increased sensitivity of the relaxation rate to strain rate in a dose dependent manner, which may explain why diastolic dysfunction is not more prevalent in clinical studies. Mav appears to only modify the attachment of crossbridges as expected.

Hierarchical Motion Estimation With Bayesian Regularization in Cardiac Elastography: Simulation and In Vivo Validation.

Cardiac elastography (CE) is an ultrasound-based technique utilizing radio-frequency (RF) signals for assessing global and regional myocardial function. In this work, a complete strain estimation pipeline for incorporating a Bayesian regularization-based hierarchical block-matching algorithm, with Lagrangian motion description and myocardial polar strain estimation is presented. The proposed regularization approach is validated using finite-element analysis (FEA) simulations of a canine cardiac deformation model that is incorporated into an ultrasound simulation program. Interframe displacements are initially estimated using a hierarchical motion estimation framework. Incremental displacements are then accumulated under a Lagrangian description of cardiac motion from end-diastole (ED) to end-systole (ES). In-plane Lagrangian finite strain tensors are then derived from the accumulated displacements. Cartesian to cardiac coordinate transformation is utilized to calculate radial and longitudinal strains for ease of interpretation. Benefits of regularization are demonstrated by comparing the same hierarchical block-matching algorithm with and without regularization. Application of Bayesian regularization in the canine FEA model provided improved ES radial and longitudinal strain estimation with statistically significant ( ) error reduction of 48.88% and 50.16%, respectively. Bayesian regularization also improved the quality of temporal radial and longitudinal strain curves with error reductions of 78.38% and 86.67% ( ), respectively. Qualitative and quantitative improvements were also visualized for in vivo results on a healthy murine model after Bayesian regularization. Radial strain elastographic signal-to-noise ratio (SNRe) increased from 3.83 to 4.76 dB, while longitudinal strain SNRe increased from 2.29 to 4.58 dB with regularization.

ASSOCIATION BETWEEN EPICARDIAL ADIPOSE TISSUE MEASURMENT BY TRANSTHORACIC ECHOCARDIOGRAPHY AND MULTISLICE COMPUTED TOMOGRAPHY IN PATIENTS WITH ABDOMINAL OBESITY

Objective: To assess the correlation between epicardial adipose tissue (EAT) thickness, measured by echocardiography, and the EAT volume, measured by multislice computed tomography (MSCT), in patients with abdominal obesity.Design and method: The study included 68 patients (57.5% - men, 42.5% - women), mean age 37.25 ± 6.88 years with abdominal obesity (waist circumference > 80 cm in women and > 94 cm in men). EAT thickness was measured using transthoracic echocardiography (SystemFive, USA) on the free wall of the right ventricle from both parasternal long and short axis views at end systole and end diastole during three cardiac cycles. EAT volume, intraabdominal visceral adipose tissue volume and subcutaneous adipose tissue volume were measured by MSCT (ToshibaAquillion 640, Japan). Results: EAT volume was positively correlated with intraabdominal visceral adipose tissue volume (r = 0,59). Negative correlation was found between EAT volume and the ratio of subcutaneous adipose tissue to intraabdominal visceral adipose tissue (r = −0,39). EAT thickness at end systole was correlated with EAT volume by MSCT (r = 0,45). There was no correlation between EAT thickness at end diastole and EAT volume. Conclusions: These data suggested that EAT is strongly associated with intraabdominal visceral adipose tissue and could indicated visceral obesity. Echocardiographic measurement of EAT was showed a significant correlation with the MSCT EAT measurements. Echocardiography EAT thickness could be used as an easy and reliable imaging indicator of visceral obesity and cardiovascular risk assessment.

Role of cardiovascular magnetic resonance end-systolic 3D-SSFP sequence in repaired tetralogy of Fallot patients eligible for transcatheter pulmonary valve implantation.

To evaluate the usefulness of cardiovascular magnetic resonance (CMR) 3D steady state free precession (SSFP) sequence acquired at end-systole (ES) in repaired Tetralogy of Fallot (rToF) patients eligible for percutaneous pulmonary valve implantation (PPVI). Between 2012 and 2018, 78 rToF patients were selected for pulmonary valve replacement (PVR) according to CMR criteria. CMR protocol included 3D-SSFP sequence used to assess the right ventricle outflow tract (RVOT) diameters at three levels (pulmonary valve remnant, mid-portion, bifurcation) in mid-diastole (MD) or ES, RVOT length and coronary artery anatomy. In 20 rToF patients without indications for PVR (controls), 3D SSFP sequence was acquired at both cardiac phases (MD and ES) to evaluate RVOT dimension throughout the cardiac cycle. Invasive balloon sizing was recorded in patients undergoing PPVI. The 3D-SSFP sequence was performed in MD on 39 patients and in ES on other 39, of whom 26 patients met the criteria for PPVI. The latter was unsuccessful in ten patients (38%), mainly due (80% of cases) to significant size discrepancy at PV remnant and bifurcation levels (p = 0.019 and 0.037 respectively) between the measurements by 3D-SSFP in MD and those by the balloon size in systole. Significant RVOT size difference between MD and ES was present at mid-portion and bifurcation levels in the PVR candidate group, and at all three-levels in the control group (all p < 0.001). ES 3D-SSFP sequence is able to quantify RVOT dilation in rToF patients at its maximum expansion, thus improving selection of PPVI candidates.

CT compared to MRI for functional evaluation of the right ventricle: a systematic review and meta-analysis.

Right ventricular function (RVF) is a strong predictor of adverse cardiac events; however, the reference standard for RVF assessment, MRI, is limited in some patients for whom accurate evaluation of RVF is essential, like those with COPD or non-MR compatible metal implants. We conducted this meta-analysis to evaluate whether CT was as accurate as MRI for the assessment of RVF. We conducted a meta-analysis of studies retrieved from PubMed, Embase, and Cochrane Central searches to evaluate the differences and correlations between the following RVF parameters as measured by CT and MRI: end diastole volume (EDV), end systole volume (ESV), right ventricular ejection fraction (RVEF), and stroke volume (SV). Sixteen studies that used disk summation (637 subjects) and three studies that used three-dimensional reconstruction were included. For the 16 studies, the pooled standard mean differences (95% confidence interval) were 1.04 (- 2.59, 4.67) for EDV, 1.22 (1.50, 3.95) for ESV, - 0.65 (- 2.60, 1.29) for RVEF, and - 0.37 (- 3.64, 2.90) for SV. The overall correlation coefficient (r) values were 0.98 for EDV, 0.95 for ESV, 0.98 for RVEF, and 0.97 for SV. The mean difference between the two methods was not statistically significant (overall effect Z test, p> 0.1). CT can assess RVF with accuracy comparable to that of MRI. Thus, CT is a valid alternative to MRI. • CT could help clinicians to assess RVF as accurately as MRI can, with satisfactory repeatability.

Near-Wall Flow in Cerebral Aneurysms

The region where the vascular lumen meets the surrounding endothelium cell layer, hence the interface region between haemodynamics and cell tissue, is of primary importance in the physiological functions of the cardiovascular system. The functions include mass transport to/from the blood and tissue, and signalling via mechanotransduction, which are primary functions of the cardiovascular system and abnormalities in these functions are known to affect disease formation and vascular remodelling. This region is denoted by the near-wall region in the present work, and we outline simple yet effective numerical recipes to analyse the near-wall flow field. Computational haemodynamics solutions are presented for six patient specific cerebral aneurysms, at three instances in the cardiac cycle: peak systole, end systole (taken as dicrotic notch) and end diastole. A sensitivity study, based on Newtonian and non-Newtonian rheological models, and different flow rate profiles, is effected for a selection of aneurysm cases. The near-wall flow field is described by the wall shear stress (WSS) and the divergence of wall shear stress (WSSdiv), as descriptors of tangential and normal velocity components, respectively, as well as the wall shear stress critical points. Relations between near-wall and free-stream flow fields are discussed.

Evaluation of cardiovascular risk by growth-differentiation factor-15 and tissue Doppler imaging in children with subclinical hypothyroidism.

Subclinical hypothyroidism, defined as increased TSH serum levels and normal serum free T4 concentrations, has been associated with an increased risk of heart disease in adults. But, data in children and adolescents are scanty and treatment of subclinical hypothyroidism is controversial. Growth differentiation factor-15 (GDF-15) is a promising biomarker of cardiac remodeling. This study aimed to evaluate the cardiovascular risk factors in children with subclinical hypothyroidism, measured with tissue Doppler echocardiography (TDE), and conventional echocardiography and GDF-15 level. The study comprised a total of 41 pediatric patients with subclinical hypothyroidism (SH) (mean age 9.6 ± 4.7 years) and 31 healthy children (mean age 11.2 ± 3.4 years) as the control group. Subclinical hypothyroidism was defined as a thyroid-stimulating hormone level higher than 4 mIU/l and a normal free-thyroxine level (0.6-1.8 ng/dl). Tissue Doppler echocardiography was performed to all individuals in the control group and patient group at the beginning of the study. Global systolic function as assessed by left ventricular ejection fraction was compared between groups. The serum GDF-15 level was measured. There were no significant differences in demographic parameters between the SH and control groups. The left ventricular internal diameter end systole, interventricular septal end diastole, left ventricular posterior wall end diastole, and tricuspid annular plane systolic excursion values were significantly different between the SH and control groups (p = 0.038, 0.028, 0.005, and 0.000, respectively). The mean mitral isovolumic relaxation time value of the SH group was 57.2 ± 9.3 ms, compared to 44.5 ± 5.6 ms for the control group (p = 0.000). The mean tricuspid isovolumic contraction time value of the SH group was 58.7 ± 9.4 ms, and that of the control group was 45.1 ± 5.3 ms (p = 0.000). The mean tricuspid isovolumic relaxation time value of the SH group was 58.03 ± 9.5 ms, and that of the control group was 45.1 ± 5.3 ms (p = 0.000). There were no significant differences in the other m-mode or pulse Doppler echocardiography values between two groups. The GDF-15 value of the SH group was 382.6 ± 268.2 pg/mL, and that of the control group was 473.6 ± 337.9 pg/mL; this difference was not significant. Patients with subclinical hypothyroidism versus healthy individuals had some changes in echocardiographic parameters that indicate involvement of diastolic function of the left ventricle. They were significantly different when compared SH group and the control group. This study demonstrated ventricle diastolic dysfunction in pediatric patients with hypothyroidism. The results of our study suggest that cardiac follow-up may be useful in patients with subclinical hypothyroidism and clinical trials are needed to explore therapeutic effects of T4 and T3 administration in this patients.

Abstract 197: Predictors of Early Left Ventricular Ejection Fraction Recovery in Patients Following Transcatheter Aortic Valve Replacement

Background: Transcatheter aortic valve replacement (TAVR) is recommended by guidelines in severe aortic stenosis (AS) in patients with high or intermediate surgical risk. However, AS and reduced left ventricular ejection fraction (LVEF) is associated with worse clinical outcomes. Many of these patients will have LVEF recovery after TAVR. The purpose of this study was to evaluate the predictors of early LVEF recovery. Methods: All patients with a baseline LVEF &lt; 50% who underwent TAVR and had an echocardiogram within one-month post-TAVR (n=39) at a single center were included to determine the factors that predict an improvement in early LVEF. A 10% increase in LVEF within one month was used as a definition of early improvement in LVEF. Chi-square and T-test were used to examine differences in baseline characteristics between subjects with and without improvement in early LVEF. Results: The patient cohort was 77 ± 9 years, 76.9% male, STS 6.2 ± 3.7. Among the 56% who had an improvement in early LVEF, they were more likely to have a lower left ventricular end diastolic diameter (LVEDD) (5.0±0.8 cm vs. 5.7±0.6 cm; p-value = 0.01) and left ventricular end systole diameter (LVESD) (3.7±0.8 cm vs. 4.5±1.1 cm; p-value = 0.02). These patients were more likely to have a higher interventricular septum diastolic thickness (IVSd) (1.2±0.2 cm vs. 1.0±0.2 cm; p-value = 0.01) and less likely to have a pre-existing peripheral vascular disease (PVD; 13% vs. 50%; p-value=0.01). Conclusion: Our study suggests that LVEDD, LVESD, IVSd, and PVD may be used to predict early improvement in LVEF. These factors need to be further prospectively validated to determine patients who are more likely to benefit from TAVR.

Quantification of myocardial uptake rate constants in dynamic small-animal SPECT using a cardiac phantom

Myocardial blood flow and myocardial blood flow reserve (MBFR) measurements are often used clinically to quantify coronary microvascular function. Developing imaging-based methods to measure MBFR for research in mice would be advantageous for evaluating new treatment methods for coronary microvascular disease (CMVD), yet this is more challenging in mice than in humans. This work investigates microSPECT’s quantitative capabilities of cardiac imaging by utilizing a multi-part cardiac phantom and applying a known kinetic model to synthesize kinetic data from static data, allowing for assessment of kinetic modeling accuracy. The phantom was designed with four main components: two left-ventricular (LV) myocardial sections and two LV blood-pool sections, sized for end-systole (ES) and end-diastole (ED). Each section of the phantom was imaged separately while acquiring list-mode data. These static, separate-compartment data were manipulated into synthetic dynamic data using a kinetic model representing the myocardium and blood-pool activity concentrations over time and then combined into a set of dynamic image frames and reconstructed. Regions of interest were drawn on the resulting images, and kinetic parameters were estimated. This process was performed for three tracer uptake values (K1), three myocardial wall thicknesses, ten filter parameters, and 20 iterations for 25 noise ensembles. The degree of filtering and iteration number were optimized to minimize the root mean-squared error (RMSE) of K1 values, with the largest number of iterations and minimal filtering yielding the lowest error. Using the optimized parameters, K1 was determined with reasonable error (~3% RMSE) over all wall thicknesses and K1 input values. This work demonstrates that accurate and precise measurements of K1 are possible for the U-SPECT+ system used in this study, for several different uptake rates and LV dimensions. Additionally, it allows for future investigation utilizing other imaging systems, including PET studies with any radiotracer, as well as with additional phantom parts containing lesions.

Immediate Reduction in Left Ventricular Wall Stress Post Transcatheter Aortic Valve Replacement

Background: Patients with aortic stenosis (AS) may have other competing comorbidities to account for their symptoms. Left ventricular wall stress (LVWS) is increased in patients with severe AS and is likely to be an indicator of AS severity, however the immediate effects of transcatheter aortic valve replacement (TAVR) have not been documented. We assessed acute changes in LVWS post TAVR. Methods: Six patients (median age 82 years (IQR 81.8–84)) undergoing TAVR for severe, symptomatic AS (median AV V max: 4.1 m/s (3.8–4.4), AVA 0.7 cm2 (0.68–0.85)) underwent MRI within 24 hours prior to TAVR. CMR-derived volumes were integrated with invasive haemodynamic data obtained using conductance catheters, to construct pressure-volume (PV) loops immediately before and after valve implantation. Pressures obtained on PV-loops were used to derive regional end-systolic (ES) and end-diastolic (ED) LVWS pre- and post-intervention (for 7 contiguous SAX planes). Results: TAVR was associated with a significant reduction in average ES-LVWS (7.8 to 5.7 × 103 N/m2, p = 0.046). There was a non-significant trend to suggest a reduction in median LV-ESP (133 mmHg pre, 129 mmHg post, p = 0.6), LV-EDP (15 mmHg pre, 13 mmHg post, p = 0.46) as well as a trend to suggest a reduction in maximum regional ES-LVWS (9.8 to 9.2 × 103 N/m2, p = 0.5) and minimum regional ES-LVWS (5.6 to 4.9 × 103 N/m2, p = 0.46). In contrast there was no significant change in ED-LVWS following TAVR (average ED-LVWS 2.3 to 2.3, p = 0.46, maximum ED-LVWS 2.6–2.8 × 103 N/m2, p = 0.46). Conclusion: In patients with severe, symptomatic AS, TAVR is associated with an immediate reduction in end-systolic wall stress, however end-diastolic wall stress is unchanged.

Characterisation of Left Ventricular Shape Change as Defined by Sphericity Index in Patients with Acute Phase Takotsubo Cardiomyopathy and Anterior STEMI Patients

Background: Left ventricle (LV) shape changes have been proposed to be predictive of cardiovascular outcomes. Extreme sphericity has been shown to be a strong predictor of heart failure and atrial fibrillation. Sphericity index (SI) is a measure that may be used to quantify LV shape changes. The aim of our study was to characterise LV shape changes using SI between patients with acute phase Takotsubo's cardiomyopathy (TTC) and acute anterior transmural infarction (AMI). Methods: Consecutive TTC (n = 49) and AMI (n = 51) patients with a comprehensive transthoracic echocardiogram during index admission were examined. Standard measures of LV size and systolic function were compared between groups. Mean SI was calculated as an average of the ratio of the short-axis length to the long-axis length in 4- and 2-chamber apical views in both end-diastole (ED) and end-systole (ES). Both groups were also compared to healthy controls (n = 50) and dilated cardiomyopathy (DCM) controls (n = 39). Results: TTC and AMI patients had significantly worse LVEF and greater SI compared to normal controls suggesting LV shape change but not to the degree of DCM patients. Interestingly, there was no significant difference in LVEF between TTC (51 ± 12%) and AMI (53 ± 13%) [p = 0.52] but there was a significant difference in mean SI for TTC (0.60 ± 0.06) vs AMI (0.52 ± 0.07) [p < 0.0005] reflecting a more spherical shaped ventricle in the TTC group. Conclusions: Our results demonstrate differences in LV shape between different cardiac pathologies. Characterisation of these LV geometric changes may provide mechanistic insights into these underlying cardiac pathologies and guide management strategies.

Mitral annular disjunction in mitral valve prolapse: A Cardiac Magnetic Resonance study

Few data exist on cardiac magnetic resonance (CMR) prevalence of mitral annulus disjunction (MAD) in mitral valve prolapse (MVP) and its morphological characteristics. To assess the prevalence of MAD and its consequences on left ventricle (LV) morphology in MVP patients using CMR. 89 patients with MVP (63 women; mean age 64 ± 13) referred for CMR assessment of mitral regurgitation (MR) were evaluated. MVP etiology was either Myxomatous Mitral Valve Disease (MMVP) ( n = 40; 45%) or fibroelastic disease (FED) ( n = 49; 55%). In total, 26/89 (29%) patients underwent injected gadolinium contrast enhancement (GE). MR severity was calculated using the volumetric method with CMR. LV systolic diameter (LVSD), and mitral annulus end systolic (ES) and diastolic (ED) diameters were measured. MAD was defined as a separation between the left atrium-valve junction and the LV posterior free wall, diagnosed by CMR from long axis view in end-systole ( Fig. 1 ). Patients were classified in 2 groups according to presence (MAD+) or absence of MAD (MAD−). MAD was found in 35% (31/89) of MVP patients, measuring 8 ± 4 mm. MAD was more frequent in MMVP (24/40; 60%) than in FED (7/49; 14%; P < 0.0001). Presence of MAD was associated with ventricular arrhythmias (VA) ( P = 0.037), but not with MR severity (regurgitant volume in MAD+ was 47 ± 32 vs. 56 ± 23 ml/beat, P = 0.141). MAD+ showed enlarged basal LVSD (41 ± 9 vs. 37 ± 7 mm, P = 0.014) and mitral annulus, in both ES (49 ± 6 vs. 44 ± 5 mm, P < 0.0001) and ED (48 ± 5 vs. 44 ± 4 mm, P = 0.004). Among the 11/26 patients (42%) with late GE, 83% (5/6) of the patients with LV fibrosis at the level of papillary muscle (PM) had MAD. After adjustment on age and MR severity, MMVP (HR 5.04; 95% CI [1.66–15.31], P = 0.004) and dilated ES mitral annulus diameter (HR 1.17; 95% CI [1.05–1.30], P = 0.005) were independent predictors of MAD ( Table 1 ). MMVP, enlarged LVSD, enlarged mitral annular, VA and PM fibrosis were associated with MAD, independently of MR severity.

Cardiac Phase Detection in Echocardiograms With Densely Gated Recurrent Neural Networks and Global Extrema Loss.

Accurate detection of end-systolic (ES) and end-diastolic (ED) frames in an echocardiographic cine series can be difficult but necessary pre-processing step for the development of automatic systems to measure cardiac parameters. The detection task is challenging due to variations in cardiac anatomy and heart rate often associated with pathological conditions. We formulate this problem as a regression problem and propose several deep learning-based architectures that minimize a novel global extrema structured loss function to localize the ED and ES frames. The proposed architectures integrate convolution neural networks (CNNs)-based image feature extraction model and recurrent neural networks (RNNs) to model temporal dependencies between each frame in a sequence. We explore two CNN architectures: DenseNet and ResNet, and four RNN architectures: long short-term memory, bi-directional LSTM, gated recurrent unit (GRU), and Bi-GRU, and compare the performance of these models. The optimal deep learning model consists of a DenseNet and GRU trained with the proposed loss function. On average, we achieved 0.20 and 1.43 frame mismatch for the ED and ES frames, respectively, which are within reported inter-observer variability for the manual detection of these frames.

Heart filling exceeds emptying during late ventricular systole in patients with systolic heart failure and healthy subjects - a cardiac MRI study.

SummaryBackgroundTotal heart volume (THV) within the pericardium is not constant throughout the cardiac cycle and THV would intuitively be lowest at end systole. We have, however, observed a phase shift between ventricular outflow and atrial inflow which causes the minimum THV to occur before end systole. The aims were to explain the mechanism of the late‐systolic net inflow to the heart and determine whether this net inflow is affected by increased cardiac output or systolic heart failure.Methods and ResultsHealthy controls (n = 21) and patients with EF<35% (n = 14) underwent magnetic resonance imaging with flow measurements in vessels to and from the heart, and this was repeated in nine controls during 140 μgram kg−1 min−1 adenosine infusion. Minimum THV occurred 78 ± 6 ms before end of systolic ejection (8 ± 1% of the cardiac cycle) in controls. The late‐systolic net inflow was 12·3 ± 1·1 ml or 6·0 ± 0·5% of total stroke volume (TSV). Cardiac output increased 66 ± 8% during adenosine but late‐systolic net inflow to the heart did not change (P = 0·73). In patients with heart failure, late‐systolic net inflow of the heart′s left side was lower (3·4 ± 0·5%) compared to healthy subjects (5·3 ± 0·6%, P = 0·03).ConclusionsHeart size increases before end systole due to a late‐systolic net inflow which is unaffected by increased cardiac output. This may be explained by inertia of blood that flows into the atria generated by ventricular systole. The lower late‐systolic net inflow in patients with systolic heart failure may be a measure of decreased ventricular filling due to decreased systolic function, thus linking systolic to diastolic dysfunction.

Contractility surrogates derived from three-dimensional lead motion analysis and prediction of acute haemodynamic response to CRT

BackgroundPatient-specific left ventricular (LV) lead optimisation strategies with immediate feedback on cardiac resynchronisation therapy (CRT) effectiveness are needed. The purpose of this study was to compare contractility surrogates derived from...

ECHOCARDIOGRAPHIC PARAMETERS IN EIGHT ADULT TIGERS ( PANTHERA TIGRIS) DURING TWO PHASES OF AN ANESTHETIC PROTOCOL.

Eight adult tigers ( Panthera tigris) underwent a complete echocardiographic examination following sedation with medetomidine, midazolam, and induction of general anesthesia using ketamine and isoflurane (phase 1). Atipamezole was used to antagonize medetomidine (phase 2) and a second echocardiographic examination was performed. Physiologic tricuspid and pulmonic regurgitations were common findings in the sample population and one tiger was excluded from final analyses due to the finding of a ventricular septal defect. Measurements and mean arterial pressure were assessed for statistically significant differences between the two examination phases as well as gender and weight. There was a statistically significant difference between interventricular septum thickness at end systole, ejection fraction, and mean arterial pressure between anesthetic phases while fractional shortening and left ventricular internal dimension at end-systole approached, but did not reach, statistical significance between phases. Weight was found to be a statistically significant predictor of stroke volume and left ventricular internal dimension at end-diastole. The echocardiographic measurements obtained during this study can be used as guidelines for future examinations in adult tigers. The effects of medetomidine on these measurements and systolic function should be taken into account when performing echocardiograms and monitoring anesthetic events.

Abstract 17396: RV Remodeling in Two Animal Models of Pulmonary Arterial Hypertension

Introduction: Right-ventricular function is a good indicator of pulmonary arterial hypertension (PAH) prognosis. By relating ventricular hemodynamics to wall mechanics, we aimed to discriminate the contributions of ventricular geometric remodeling and intrinsic changes in myocardial mechanical properties in two commonly used PAH animal models at end-systole (ES) and end-diastole (ED) to the maintenance of cardiac output during the early compensated phase. Methods: PAH was induced in 13 male Sprague-Dawley rats. The MCT group (N=4) was injected with a single dose of 60mg/kg of monoctroaline and kept in normoxia for 4 weeks. The SuHx group (N=9) was injected with a single dose of 20mg/kg of sugen, a VEGF inhibitor, and was placed on a hypoxia chamber for 3 weeks followed by 3 weeks of normoxia. 7 animals were used as a control group. In-vivo measurements of RV pressure and volume with preload changes were acquired. To relate ventricular pressure-volume relations to sarcomere mechanics, a computational model of the RV was developed. Using ventricular morphology and volume measurements from PAH groups, sarcomere material mechanics were adjusted to evaluate ES and ED functions in the treated animals. Results: ED pressures rose significantly in the treated groups (31.7 vs. 70.5 and 71.1 mmHg). ED and ES volumes remained the same in SuHx and CTL group, but increased significantly in the MCT group. RV hypertrophy increased in both PAH animal models, but it was significantly higher in the SuHx group. Even though differences in pressure, volume and morphology exist between the PAH groups, SV and CO were preserved in all treated animals. Model material parameters of increased in PAH, significantly in MCT maximal isometric tension. Conclusions: The model analysis suggests compensation to ESP rises was only possible due to a significant increase in the contractility of RV myocardium in the MCT and SuHx animals. No changes in diastolic function were found in the MCT animals, but there was an increase stiffness in the SuHx animals.

NT-proBNP level and left ventricle diameters before and after transcatheter closure of PDA and VSD

Background Amino-terminal pro-B-type natriuretic peptide (NT-proBNP) levels before and after transcatheter closure may correlate with changes in left ventricular internal diameter end diastole (LVIDd) and end systole (LVIDs). Patent ductus arteriosus (PDA) and ventricular septal defect (VSD) are structural abnormalities which effects cardiac hypertrophy. Cardiac muscle stretching decreases after closure, followed by reduced left ventricle diameters and decreased NT-proBNP levels.&#x0D; Objective To analyze for possible correlations between NT-proBNP levels and left ventricle diameters before and after transcatheter closure.&#x0D; Methods Subjects were PDA and VSD patients who underwent transcatheter closure in the Pediatrics Department of dr. Moh Hoesin Hospital, Palembang, South Sumatera, from May 2016 to March 2017. Measurement of NT-proBNP levels and echocardiography were performed before closure, as well as one and three months after closure.&#x0D; Results There were 34 subjects (15 girls) with median age of 91.5 months. Median NT-proBNP levels were significantly reduced after closure: before closure 111.7pg/mL, one month after closure 62pg/mL, and three months after closure 39 pg/mL (P&lt;0.05). Median LVIDd and LVIDs were also significantly reduced after closure [LVIDd: 39.5mm before, 34.5mm one mo after, and 32.5mm 3 mo after (P&lt;0.05); LVIDs: 23.9mm before, 20.5mm 1 mo after, and 20.0mm 3 mo after (P&lt;0.05)]. At one month after closure, there was a moderate positive correlation between NT-proBNP levels and LVIDd (r=0.432; P=0.011), but no correlation with LVIDs (r=0.287; P=0.100). At three months after closure, there was a significant moderate positive correlation between changes of NT-proBNP levels and changes of LVIDd (r=0.459; P=0.006), as well as LVIDs (r=0.563; P=0.001).&#x0D; Conclusion In pediatric PDA and VSD patients, NT-proBNP levels have a significant positive correlation with diastolic and systolic left ventricle diameters at three months after closure. Decreased NT-proBNP levels may be considered as a marker of closure effectiveness.

Effect of patient positioning on the evaluation of myocardial perfusion SPECT

BackgroundECG-gated SPECT myocardial perfusion imaging is usually acquired in supine position. However, some patients are not comfortable in this position for a variety of personal or medical reasons. Our aim was to investigate the effect of patient positioning on quantitative SPECT imaging results using normal supine database. Methods55 patients (mean age 58.5 ± 8.3 years) were enrolled in this prospective study. Each patient had a pair of ECG-gated stress SPECT myocardial perfusion images acquired on two gamma cameras: one in supine position and the other in upright sitting position. Left ventricular (LV) ejection fraction (EF), end-diastolic (ED), and end-systolic (ES) left ventricular volumes (V), LV mass, summed stress perfusion defect score (SSS), and total severity score (TSS) were calculated automatically relative to a supine normal reference database. ResultsThere were no significant differences in LVEF using the two cameras (0.65 ± 0.08 vs. 0.66 ± 0.10; P > 0.1). However, EDV, ESV, and LV mass were significantly smaller in sitting position than in supine position (89 vs. 80 ml; 33 vs. 29 ml and 115 vs. 109 ml, respectively, all P < 0.0001). On the other hand, SSS and TSS were significantly higher in sitting position than in supine position (5.16 vs. 8.73 and 166.82 vs. 288.27, both P < 0.0001). Overall, more studies in sitting position were interpreted as abnormal than in supine position (P < 0.05). ConclusionPatient positioning has a significant impact on quantitative gated SPECT imaging results. Using a supine normal reference database, SSS and TSS were larger in sitting position than in supine position. Thus, for imaging in sitting position, separate normal limits are required.