Analysis of global systolic and diastolic left ventricular performance using volume-time curves by real-time three-dimensional echocardiography

Imaging techniques for the assessment of adverse cardiac remodeling in metabolic syndrome

Metabolic syndrome (MetS) includes different metabolic conditions (i.e. abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, decreased HDL cholesterol, and/or hypertension) that concour in the development of cardiovascular disease and diabetes. MetS individuals often show adverse cardiac remodeling and myocardial dysfunction even in the absence of overt coronary artery disease or valvular affliction. Diastolic impairment and hypertrophy are hallmarks of MetS-related cardiac remodeling and represent the leading cause of heart failure with preserved ejection fraction (HFpEF). Altered cardiomyocyte function, increased neurohormonal tone, interstitial fibrosis, coronary microvascular dysfunction, and a myriad of metabolic abnormalities have all been implicated in the development and progression of adverse cardiac remodeling related to MetS. However, despite the enormous amount of literature produced on this argument, HF remains a leading cause of morbidity and mortality in such population. The early detection of initial adverse cardiac remodeling would enable the optimal implementation of effective therapies aiming at preventing the progression of the disease to the symptomatic phase. Beyond conventional imaging techniques, such as echocardiography, cardiac tomography, and magnetic resonance, novel post-processing tools and techniques provide information on the biological processes that underlie metabolic heart disease. In this review, we summarize the pathophysiology of MetS-related cardiac remodeling and illustrate the relevance of state-of-the-art multimodality cardiac imaging to identify and quantify the degree of myocardial involvement, prognosticate long-term clinical outcome, and potentially guide therapeutic strategies.

Feasibility and Accuracy of the Automated Software for Dynamic Quantification of Left Ventricular and Atrial Volumes and Function in a Large Unselected Population

We aimed to evaluate the feasibility and accuracy of machine learning-based automated dynamic quantification of left ventricular (LV) and left atrial (LA) volumes in an unselected population. We enrolled 600 unselected patients (12% in atrial fibrillation) clinically referred for transthoracic echocardiography (2DTTE), who also underwent 3D echocardiography (3DE) imaging. LV ejection fraction (EF), LV, and LA volumes were obtained from 2D images; 3D images were analyzed using dynamic heart model (DHM) software (Philips) resulting in LV and LA volume–time curves. A subgroup of 140 patients also underwent cardiac magnetic resonance (CMR) imaging. Average time of analysis, feasibility, and image quality were recorded, and results were compared between 2DTTE, DHM, and CMR. The use of DHM was feasible in 522/600 cases (87%). When feasible, the boundary position was considered accurate in 335/522 patients (64%), while major (n = 38) or minor (n = 149) border corrections were needed. The overall time required for DHM datasets was approximately 40 seconds. As expected, DHM LV volumes were larger than 2D ones (end-diastolic volume: 173 ± 64 vs. 142 ± 58 mL, respectively), while no differences were found for LV EF and LA volumes (EF: 55% ± 12 vs. 56% ± 14; LA volume 89 ± 36 vs. 89 ± 38 mL, respectively). The comparison between DHM and CMR values showed a high correlation for LV volumes (r = 0.70 and r = 0.82, p < 0.001 for end-diastolic and end-systolic volume, respectively) and an excellent correlation for EF (r = 0.82, p < 0.001) and LA volumes. The DHM software is feasible, accurate, and quick in a large series of unselected patients, including those with suboptimal 2D images or in atrial fibrillation.

Impact of type 2 diabetes mellitus on left ventricular diastolic function in patients with essential hypertension: evaluation by volume-time curve of cardiac magnetic resonance

Background

Essential hypertension and type 2 diabetes mellitus (T2DM) are two common chronic diseases that often coexist, and both of these diseases can cause heart damage. However, the additive effects of essential hypertension complicated with T2DM on left ventricle (LV) diastolic function have not been fully illustrated. This study aims to investigate whether T2DM affects the diastolic function of the LV in patients with essential hypertension using the volume-time curve from cardiac magnetic resonance (CMR).

Methods

A total of 124 essential hypertension patients, including 48 with T2DM [HTN(T2DM +) group] and 76 without T2DM [HTN(T2DM-) group], and 52 normal controls who underwent CMR scans were included in this study. LV volume-time curve parameters, including the peak ejection rate (PER), time to peak ejection rate (PET), peak filling rate (PFR), time to peak filling rate from end-systole (PFT), PER normalized to end-diastolic volume (PER/EDV), and PFR normalized to EDV (PFR/EDV), were measured and compared among the three groups. Multivariate linear regression analyses were performed to determine the effects of T2DM on LV diastolic dysfunction in patients with hypertension. Pearson correlation was used to analyse the correlation between the volume-time curve and myocardial strain parameters.

Results

PFR and PFR/EDV decreased from the control group, through HTN(T2DM −), to HTN(T2DM +) group. PFT in the HTN(T2DM-) group and HTN(T2DM +) group was significantly longer than that in the control group. The LV remodelling index in the HTN(T2DM −) and HTN(T2DM +) groups was higher than that in the normal control group, but there was no significant difference between the HTN(T2DM −) and HTN(T2DM +) groups. Multiple regression analyses controlling for covariates of systolic blood pressure, age, sex, and heart rate demonstrated that T2DM was independently associated with PFR/EDV (β = 0.252, p < 0.05). The volume-time curve method has good repeatability, and there is a significant correlation between volume-time curve parameters (PER/EDV and PFR/EDV) and myocardial peak strain rate, especially circumferential peak strain rate, which exhibited the highest correlation (r = − 0.756 ~ 0.795).

Conclusions

T2DM exacerbates LV diastolic dysfunction in patients with essential hypertension. The LV filling model changes reflected by the CMR volume-time curve could provide more information for early clinical intervention.

Evaluation of left ventricular function in patients with acute ischaemic stroke using cine cardiovascular magnetic resonance imaging

AIMS

Heart failure (HF) is frequent in patients with acute ischaemic stroke (AIS) and associated with higher morbidity and mortality. Assessment of cardiac function in AIS patients using cardiovascular MRI (CMR) may help to detect HF. We report the rate of systolic and diastolic dysfunction in a cohort of patients with AIS using CMR and compare cine real-time (CRT) sequences with the reference of segmented cine steady-state free precession sequences.

METHODS AND RESULTS

Patients with AIS without known atrial fibrillation were prospectively enrolled in the HEart and BRain Interfaces in Acute Ischemic Stroke (HEBRAS) study (NCT02142413) and underwent CMR at 3 Tesla within 7 days after AIS. Validity of CRT sequences was determined in 50 patients. A total of 229 patients were included in the analysis (mean age 66 years; 35% women; HF 2%). Evaluation of cardiac function was successful in 172 (75%) patients. Median time from stroke onset to CMR was 82 h (interquartile range 56-111) and 54 h (interquartile range 31-78) from cerebral MRI to CMR. Systolic dysfunction was observed in 43 (25%) and diastolic dysfunction in 102 (59%) patients. Diagnostic yield was similar using CRT or segmented cine imaging (no significant difference in left ventricular ejection fraction, myocardial mass, time to peak filling rate, and peak filling rate ratio E/A). Intraobserver and interobserver agreement was high (κ = 0.78-1.0 for all modalities).

CONCLUSIONS

Cardiovascular MRI at 3 Tesla is an appropriate method for the evaluation of cardiac function in a selected cohort of patients with AIS. Systolic and diastolic dysfunction is frequent in these patients. CRT imaging allows reliable assessment of systolic and diastolic function.

Assessment of left ventricular diastolic function by three-dimensional transthoracic echocardiography

Doppler echocardiography assessment of left ventricular (LV) filling pressures at rest and during exercise is the most widely used imaging technique to assess LV diastolic function in clinical practice. However, a sizable number of patients evaluated for suspected LV diastolic function show an inconsistency between the various parameters included in the flowchart recommended by current Doppler echocardiography guidelines and results in an undetermined LV diastolic function. Current three-dimensional echocardiography technology allows obtaining accurate measurements of the left atrial volumes and functions that have been shown to improve the diagnostic accuracy and prognostic value of the algorithms recommended for assessing both LV diastolic dysfunction and heart failure with preserved ejection fraction. Moreover, current software packages used to quantify LV size and function provide also volume-time curves showing the dynamic LV volume change throughout the cardiac cycle. Examining the diastolic part of these curves allows the measurement of several indices of LV filling that have been reported to be useful to differentiate patients with normal LV diastolic function from patients with different degrees of diastolic dysfunction. Finally, several software packages allow to obtain also myocardial deformation parameters from the three-dimensional datasets of both the left atrium and the LV providing additional functional parameters that may be useful to improve the diagnostic yield of three-dimensional echocardiography for the LV diastolic dysfunction. This review summarizes the current applications of three-dimensional echocardiography to assess LV diastolic function.

Three-dimensional echocardiography to assess left ventricular geometry and function

Introduction: Quantification of left ventricular (LV) size and function represents the most frequent indication for an echocardiographic study. New echocardiographic techniques have been developed over the last decades in an attempt to provide a more comprehensive, accurate, and reproducible assessment of LV function.Areas covered: Although two-dimensional echocardiography (2DE) is the recommended imaging modality to evaluate the LV, three-dimensional echocardiography (3DE) has proven to be more accurate, by avoiding geometric assumptions about LV geometry, and to have incremental value for outcome prediction in comparison to conventional 2DE. LV shape (sphericity) and mass are actually measured with 3DE. Myocardial deformation analysis using 3DE can early detect subclinical LV dysfunction, before any detectable change in LV ejection fraction.Expert opinion: 3DE eliminates the errors associated with foreshortening and geometric assumptions inherent to 2DE and 3DE measurements approach very closely those obtained by CMR (the current reference modality), while maintaining the unique clinical advantage of a safe, highly cost/effective, portable imaging technique, available to the cardiologist at bedside to translate immediately the echocardiography findings into the clinical decision-making process.

Machine learning based quantification of ejection and filling parameters by fully automated dynamic measurement of left ventricular volumes from cardiac magnetic resonance images

BACKGROUND

Although analysis of cardiac magnetic resonance (CMR) images provides accurate and reproducible measurements of left ventricular (LV) volumes, these measurements are usually not performed throughout the cardiac cycle because of lack of tools that would allow such analysis within a reasonable timeframe. A fully-automated machine-learning (ML) algorithm was recently developed to automatically generate LV volume-time curves. Our aim was to validate ejection and filling parameters calculated from these curves using conventional analysis as a reference.

METHODS

We studied 21 patients undergoing clinical CMR examinations. LV volume-time curves were obtained using the ML-based algorithm (Neosoft), and independently using slice-by-slice, frame-by-frame manual tracing of the endocardial boundaries. Ejection and filling parameters derived from these curves were compared between the two techniques. For each parameter, Bland-Altman bias and limits of agreement (LOA) were expressed in percent of the mean measured value.

RESULTS

Time-volume curves were generated using the automated ML analysis within 2.5 ± 0.5 min, considerably faster than the manual analysis (43 ± 14 min per patient, including ~10 slices with 25-32 frames per slice). Time-volume curves were similar between the two techniques in magnitude and shape. Size and function parameters extracted from these curves showed no significant inter-technique differences, reflected by high correlations, small biases (<10%) and mostly reasonably narrow LOA.

CONCLUSION

ML software for dynamic LV volume measurement allows fast and accurate, fully automated analysis of ejection and filling parameters, compared to manual tracing based analysis. The ability to quickly evaluate time-volume curves is important for a more comprehensive evaluation of the patient's cardiac function.

Machine learning based automated dynamic quantification of left heart chamber volumes

AIMS

Studies have demonstrated the ability of a new automated algorithm for volumetric analysis of 3D echocardiographic (3DE) datasets to provide accurate and reproducible measurements of left ventricular and left atrial (LV, LA) volumes at end-systole and end-diastole. Recently, this methodology was expanded using a machine learning (ML) approach to automatically measure chamber volumes throughout the cardiac cycle, resulting in LV and LA volume-time curves. We aimed to validate ejection and filling parameters obtained from these curves by comparing them to independent well-validated reference techniques.

METHODS AND RESULTS

We studied 20 patients referred for cardiac magnetic resonance (CMR) examinations, who underwent 3DE imaging the same day. Volume-time curves were obtained for both LV and LA chambers using the ML algorithm (Philips HeartModel), and independently conventional 3DE volumetric analysis (TomTec), and CMR images (slice-by-slice, frame-by-frame manual tracing). Automatically derived LV and LA volumes and ejection/filling parameters were compared against both reference techniques. Minor manual correction of the automatically detected LV and LA borders was needed in 4/20 and 5/20 cases, respectively. Time required to generate volume-time curves was 35 ± 17 s using ML algorithm, 3.6 ± 0.9 min using conventional 3DE analysis, and 96 ± 14 min using CMR. Volume-time curves obtained by all three techniques were similar in shape and magnitude. In both comparisons, ejection/filling parameters showed no significant inter-technique differences. Bland-Altman analysis confirmed small biases, despite wide limits of agreement.

CONCLUSION

The automated ML algorithm can quickly measure dynamic LV and LA volumes and accurately analyse ejection/filling parameters. Incorporation of this algorithm into the clinical workflow may increase the utilization of 3DE imaging.

4D cardiac magnetic resonance imaging, 4D and 2D transthoracic echocardiography: a comparison of in-vivo assessment of ventricular function in rats

Preclinical cardiovascular research is the foundation of our understanding and broad knowledge of heart function and cardiovascular disease. Reliable cardiac imaging modalities are the basis for applicable results. Four-dimensional cardiac magnetic resonance (4D CMR) has been set as the gold standard for in-vivo assessment of ventricular function in rodents. However, technical improvements in echocardiography now allow us to image the whole heart, which makes four-dimensional echocardiography (4DE) a possible alternative to 4D CMR. To date, no study has systematically assessed 4DE in comparison with 4D CMR in rats. In total we studied 26 juvenile Sprague-Dawley rats (Crl: CD (SD) IGS). Twenty rats underwent echocardiographic imaging (2D and 4D) and 4D CMR. Five of those rats underwent a ligation of the superior and inferior vena cava to reduce the cardiac inflow as a disease model. Six additional rats were used to assess reproducibility of echocardiography and underwent three echocardiographic examinations. 4D CMR was performed on a 7T scanner; 2D and 4D echocardiography was conducted using a 40 MHz transducer. Correlation between 4D CMR, 4DE and 2DE for left-ventricular ejection fraction (LVEF) was assessed. An excellent correlation was observed between 4DE and 4D CMR ( r = 0.95, p < 0.001). Correlation of 2DE and 4D CMR was weak ( r = 0.57, p < 0.01). 4DE provides results that are equally precise as 4D CMR and highly reproducible with less technical effort than 4D CMR.

The relative contribution of metabolic and structural abnormalities to diastolic dysfunction in obesity

Background:

Obesity causes diastolic dysfunction, and is one of the leading causes of heart failure with preserved ejection fraction. Myocardial relaxation is determined by both active metabolic processes such as impaired energetic status and steatosis, as well as intrinsic myocardial remodelling. However, the relative contribution of each to diastolic dysfunction in obesity is currently unknown.

Methods:

Eighty adult subjects (48 male) with no cardiovascular risk factors across a wide range of body mass indices (18.4–53.0 kg m⁻²) underwent magnetic resonance imaging for abdominal visceral fat, left ventricular geometry (LV mass:volume ratio) and diastolic function (peak diastolic strain rate), and magnetic resonance spectroscopy for PCr/ATP and myocardial triglyceride content.

Results:

Increasing visceral obesity was related to diastolic dysfunction (peak diastolic strain rate, r=−0.46, P=0.001). Myocardial triglyceride content (β=−0.2, P=0.008), PCr/ATP (β=−0.22, P=0.04) and LV mass:volume ratio (β=−0.61, P=0.04) all independently predicted peak diastolic strain rate (model R² 0.36, P<0.001). Moderated multiple regression confirmed the full mediating roles of PCr/ATP, myocardial triglyceride content and LV mass:volume ratio in the relationship between visceral fat and peak diastolic strain rate. Of the negative effect of visceral fat on diastolic function, 40% was explained by increased myocardial triglycerides, 39% by reduced PCr/ATP and 21% by LV concentric remodelling.

Conclusions:

Myocardial energetics and steatosis are more important in determining LV diastolic function than concentric hypertrophy, accounting for more of the negative effect of obesity on diastolic function than LV geometric remodelling. Targeting these metabolic processes is an attractive strategy to treat diastolic dysfunction in obesity.

Post-transitional adaptation of the left heart in uncomplicated, very preterm infants

BACKGROUND

The postnatal period in preterm infants involves multiple physiological changes occurring immediately after birth and continuing for days or weeks. To recognise and treat compromise, it is important to measure cardiovascular function. The aim of this study was to describe longitudinal left ventricular function using conventional and novel echocardiography techniques in preterm infants who did not experience significant antenatal or postnatal complications and treatments.

METHODS

We prospectively obtained cardiac ultrasound images at days 3, 7, 14, 21, and 28 in 25 uncomplicated, preterm infants <30 weeks of gestation. Speckle tracking analysis of the four chambers and short-axis images provided parameters of left ventricular volume, deformation, and basal myocardial velocities. The patent ductus arteriosus, cardiac dimensions, and atrial volume were also measured.

RESULTS

Stroke volume increased by 24% during the study period (1.05-1.30 ml/kg, p<0.05). Cardiac length, diameter, and systolic basal myocardial velocity increased with unchanged wall stress and deformation parameters. Diastolic function parameters resembled that of the fetus with predominance of atrial contraction compared with early diastolic velocities. Blood pressure and estimates of left ventricular filing pressure increased, suggesting that left ventricular compliance did not change in this period.

CONCLUSION

Stroke volume increased in the first 28 days after preterm birth. The preterm heart adapted by increasing its size, while maintaining systolic and atrial function, independent of early diastolic maturation. Longitudinal deformation of the left ventricle remained unchanged, suggesting relatively preserved function with maturation.

Volume-time curve of cardiac magnetic resonance assessed left ventricular dysfunction in coronary artery disease patients with type 2 diabetes mellitus

BACKGROUND

Type 2 diabetes mellitus (DM2) may induce epicardial coronary artery diseases and left ventricular myocardial damaging as well. Left ventricular dysfunction was found in DM2. In this research, we compared the left ventricular dysfunction of coronary artery disease (CAD) patients with and without type 2 diabetes mellitus as well as normal controls using the volume-time curve of cardiac magnetic resonance (CMR).

METHODS

Sixty-one CAD patients (28 with DM2 and 33 without DM2) and 18 normal individuals were enrolled in this study. Left ventricular function parameters, including the end-diastolic and end-systolic volumes (EDV, ESV), stroke volume (SV) and ejection fraction (EF), and morphologic dimension parameters (end diastolic and systolic diameter (EDD and ESD), were measured and compared. Volume-time curve parameters, including the peak ejection rate (PER), peak ejection time (PET), peak filling rate (PFR), peak filling time from ES (PFT), peak ejection rate normalized to EDV (PER/EDV), and peak filling rate normalized to EDV (PFR/EDV), were derived automatically and compared.

RESULTS

LVEF in the diabetic CAD group was markedly reduced when compared to the normal and CAD without DM2 groups (all p < 0.05). LVEDD of the diabetic CAD group was significantly enlarged compared to the normal and non-diabetic CAD groups (all p < 0.05). More importantly, the lowest parameters of the left ventricle volume time curve (i.e., PER, PFR, PER/EDV and PFR/EDV) were obtained in diabetic CAD patients (all p < 0.05). In diabetic CAD patients, logistic regression analysis indicated that PET, PFT and PFR/EDV were independent predictors of left ventricular dysfunction (odds ratio [OR]: 1.1208, 1.0161, and 0.0139, respectively). The sensitivity and specificity of PET were 81.2 and 90%, respectively, when the threshold value was greater than 164.4 msec; for PFT, the sensitivity and specificity were 87.5 and 95.0%, respectively (criterion >166.0 msec). Higher sensitivity (87.5%) and specificity (100.0%) were obtained for PFR/EDV (criterion ≤3.7EDV/s).

CONCLUSIONS

Parameters that are derived from the volume-time curve on CMR, including PET, PFT and PFR/EDV, allow clinicians to predict left ventricular dysfunction in diabetic CAD subjects with a high degree of sensitivity and specificity.

IN-SILICO MODELING OF LEFT VENTRICLE TO SIMULATE DILATED CARDIOMYOPATHY AND CF-LVAD SUPPORT

Numerical modeling of the left ventricle dynamics plays an important role in testing different physiological scenarios and treatment techniques before the in vitro and in vivo assessments. However, utilized left ventricle model becomes vital in the simulations because validity of the results depends on the response of the numerical model to the parameter changes and additional sub-models for the applied treatment techniques. In this study, it is aimed to evaluate different numerical left ventricle models describing healthy and failing ventricle dynamics as well as the response of these models under continuous flow left ventricular assist device support. Six different numerical left ventricle models which include time varying elastance and single fiber contraction approaches are selected and applied in combination with a closed loop electric analogue of the circulation to achieve this purpose. The time varying elastace models relate ventricular pressure and volume changes in a simplistic way while the single fiber contraction models combine different scales ranging from protein to organ level. Change of the hemodynamic signals at the organ level for healthy, failing and CF-LVAD supported left ventricle models shows functionality of these models and helps to understand usability of them for different purposes.

Diastolic dysfunction measured by cardiac magnetic resonance imaging in women with signs and symptoms of ischemia but no obstructive coronary artery disease

BACKGROUND

Women with chest pain and no obstructive coronary artery disease often have coronary microvascular dysfunction (CMD), diagnosed by invasive coronary reactivity testing (CRT). The relationship between CMD and diastolic function measured by cardiac magnetic resonance imaging (CMR) is not well described.

METHODS

41 women with suspected CMD underwent CRT and CMR. Left ventricular end-diastolic pressure (LVEDP), coronary flow reserve (CFR) and coronary blood flow (CBF) were measured invasively. Resting CMR of these women and 20 reference controls was assessed for LV mass, septal wall thickness, ejection fraction (LVEF), end-diastolic volume (EDV), peak filling rate (PFR) and time-to-peak-filling rate (tPFR). Pearson correlations and linear regression models were made.

RESULTS

Mean age was 55±9, all had LVEF≥50%, and 16/41 (40%) had LVEDP>15mmHg. CMD (CFR<2.5 or CBF<50%) was present in 34/41 (83%) women. tPFR (mean 178±110ms) and PFR (mean 3.2±0.64 EDV/s) were not significantly different in women with or without CMD. tPFR increased with age (r=0.37, p=0.017) and septal wall thickness (r=0.47, p=0.002), while PFR decreased with age (r=-0.45, p=0.003). There was an inverse relationship between CFR and tPFR (r=-0.3, p=0.058). Increasing mass was associated with decreasing CBF (p=0.02). Compared to controls, cases had lower LVEF (p=0.049) and lower EDV (p=0.0002).

CONCLUSION

In women with signs and symptoms of ischemia but no obstructive coronary artery disease, CMD and elevated LVEDP are prevalent. While non-endothelial dependent CMD may be related to diastolic dysfunction, further investigation is needed regarding links between CMD, diastolic dysfunction and the development of heart failure with preserved LVEF.

Three-dimensional echocardiography in various types of heart disease: a comparison study of magnetic resonance imaging and 64-slice computed tomography in a real-world population

BACKGROUND

Accurate quantification of left ventricular (LV) volumes [end-diastolic volume (EDV) and end-systolic volume (ESV)] and ejection fraction (EF) is of critical importance. The development of real-time three-dimensional echocardiography (RT3DE) has shown better correlation than two-dimensional (2D) echocardiography with magnetic resonance imaging (MRI) measurements. The aim of our study was to assess the accuracy of RT3DE and 64-slice computed tomography (CT) in the evaluation of LV volumes and function using MRI as the reference standard in a real-world population with various types of heart disease with different chamber geometry.

METHODS

The study population consisted of 66 patients referred for cardiac MRI for various pathologies. All patients underwent cardiac MRI, and RT3DE and 64 slices CT were then performed on a subsequent day. The study population was then divided into 5 clinical groups depending on the underlying heart disease.

RESULTS

RT3DE volumes correlated well with MRI values (R ² values: 0.90 for EDV and 0.94 for ESV). RT3DE measurements of EF correlated well with MRI values (R ² = 0.86). RT3DE measurements resulted in slightly underestimated values of both EDV and ESV, as reflected by biases of -9.18 and -4.50 mL, respectively. Comparison of RT3DE and MRI in various types of cardiomyopathies showed no statistical difference between different LV geometrical patterns.

CONCLUSION

These results confirm that RT3DE has good accuracy in everyday clinical practice and can be of clinical utility in all types of cardiomyopathy independently of LV geometric pattern, LV diameter or wall thickness, taking into account a slight underestimation of LV volumes and EF compared to MRI.

A mathematical model of pressure and flow waveforms in the aortic root

The differences in the pressure and flow waveforms in the aortic root have not been explained so far in a satisfactory mathematical way. It is a generally accepted idea that the existence of the reflected wave causes the differences in shapes of pressure and flow. In this paper, a mathematical model is proposed that explains the blood pressure and flow waveforms based on changes in left ventricular volume during blood ejection into the aorta. According to the model, a change in volume of the left ventricle during contraction can be mathematically presented with solutions of differential equations that describe the behavior of a second-order system. The proposed mathematical equations of pressure and flow waveforms are derived from left ventricular volume change and basic equations of fluid dynamics. The position of the reflected wave depends on the age and elasticity of arteries, and has an effect on the flow and pressure waveforms. The model is in acceptable agreement with the experimental data available.

Cardiac Function After the Immediate Transitional Period in Very Preterm Infants Using Speckle Tracking Analysis

BACKGROUND

The postnatal period in preterm infants involves multiple physiologic changes starting directly after birth and continuing for days or weeks. To recognize and treat compromise, it is important to measure cardiovascular function. We used a novel technique (speckle tracking echocardiography, STE) to measure cardiac function in this period.

METHODS

We obtained cardiac ultrasound images at day 3, 7, 14, 21 and 28 in preterm infants <30-week gestation. Conventional measures included cardiac size, left ventricular stroke volume, atrial volume and the patent ductus arteriosus (PDA). Four chamber images were analyzed with STE, which provided parameters of left ventricular volume, longitudinal deformation and myocardial velocities.

RESULTS

Images of 54 infants (gestational age 23-29 weeks) were analyzed. STE-derived stroke volume correlated well with conventional echocardiography-derived stroke volume, but agreement was suboptimal. Most STE parameters showed good reliability. All volume parameters and systolic and atrial velocities increased over time. Cardiac deformation and early diastolic velocity did not change. A PDA was associated with 33 % increased stroke volume at day 3 up to 98 % at day 28 with a spherically enlarged heart and increased filling pressure.

CONCLUSION

Speckle tracking echocardiography analysis is a feasible and reliable technique that can simultaneously obtain systolic and diastolic volumes, longitudinal deformation and myocardial velocities from one ultrasound window. Preterm hearts maintain cardiac function well during the first weeks of life, even with increased preload as a consequence of a PDA.

Exacerbation of cardiac energetic impairment during exercise in hypertrophic cardiomyopathy: a potential mechanism for diastolic dysfunction

AIMS

Hypertrophic cardiomyopathy (HCM) is the commonest cause of sudden cardiac death in the young, with an excess of exercise-related deaths. The HCM sarcomere mutations increase the energy cost of contraction and impaired resting cardiac energetics has been documented by measurement of phosphocreatine/ATP (PCr/ATP) using (31)Phosphorus MR Spectroscopy ((31)P MRS). We hypothesized that cardiac energetics are further impaired acutely during exercise in HCM and that this would have important functional consequences.

METHODS AND RESULTS

(31)P MRS was performed in 35 HCM patients and 20 age- and gender-matched normal volunteers at rest and during leg exercise with 2.5 kg ankle weights. Peak left-ventricular filling rates (PFRs) and myocardial perfusion reserve (MPRI) were calculated during adenosine stress. Resting PCr/ATP was significantly reduced in HCM (HCM: 1.71 ± 0.35, normal 2.14 ± 0.35 P < 0.0001). During exercise, there was a further reduction in PCr/ATP in HCM (1.56 ± 0.29, P = 0.02 compared with rest) but not in normals (2.16 ± 0.26, P = 0.98 compared with rest). There was no correlation between PCr/ATP reduction and cardiac mass, wall thickness, MPRI, or late-gadolinium enhancement. PFR and PCr/ATP were significantly correlated at rest (r = 0.48, P = 0.02) and stress (r = 0.53, P = 0.01).

CONCLUSION

During exercise, the pre-existing energetic deficit in HCM is further exacerbated independent of hypertrophy, perfusion reserve, or degree of fibrosis. This is in keeping with the change at the myofilament level. We offer a potential explanation for exercise-related diastolic dysfunction in HCM.

Effects of alcohol septal ablation on left ventricular diastolic filling patterns in obstructive hypertrophic cardiomyopathy

Alcohol septal ablation (ASA) has been shown to improve left ventricular (LV) diastolic function in patients with obstructive hypertrophic cardiomyopathy (HCM). However, its beneficial effect on diastolic function assessed by cardiac magnetic resonance (CMR) has not been reported. We investigated the mid-term changes of diastolic function by CMR combined with echocardiography in HCM patients after ASA at a median of 14-month follow-up. CMR parameters of diastolic function including peak filling rate (PFR), and time to peak filling rate (TPFR) were evaluated in 43 patients (aged 48 ± 9 years). LV diastolic function improved significantly measured by echocardiography with the decrease in ratio of transmitral early LV filling velocity (E) to early diastolic mitral lateral annular velocity (E') (14.20 ± 1.17 to 11.58 ± 1.16, p < 0.001) and E-wave deceleration time (194.04 ± 19.30 to 168.45 ± 12.58 ms, p < 0.001). PFR increased significantly with associated decrease in TPFR after ASA (both p < 0.001) at follow-up. Furthermore, patients with larger decrease in LVOT gradients had a greater improvement of LV diastolic function, as measured by the reduction of E/E' (p < 0.001) and increase of PFR (p < 0.001). In conclusion, this study demonstrated that successful ASA results in both echocardiographic and CMR indices of diastolic function improvement after ASA at 14-month follow-up. ASA therapy can significantly reduce LVOT gradient and mitral regurgitation, both of which may contribute to the improvement of diastolic function.

Intertwin cardiac status at 10-year follow-up after intrauterine laser coagulation therapy of severe twin-twin transfusion syndrome: comparison of donor, recipient and normal values

BACKGROUND

In twin-to-twin transfusion syndrome (TTTS), genetically identical twins are exposed to different haemodynamic conditions during fetal life, which are considered to be the cause of prenatal and postnatal cardiovascular differences between the donor and the recipient.

OBJECTIVE

To assess intertwin differences on childhood cardiac outcome after intrauterine laser coagulation therapy (LC) of severe TTTS.

DESIGN AND PATIENTS

Prospective, detailed, echocardiographic follow-up of 31 twin pairs aged 9.95±0.8 years (mean±SD) with severe TTTS treated by LC, and the comparison with reference values.

RESULTS

Cardiac function was normal and did not show intertwin differences in twins without structural heart disease. Discordant birth weight or birth weight <3rd centile for gestational age had no influence on blood pressure and cardiac indices. Pulmonary stenosis was more common (5/62; 8.1%) than in the general population (prevalence 0.066%, relative risk 134.4, 95% CI 42.1 to 428.8, p<0.0001) and affected both donor and recipient. Intertwin differences in late diastolic right ventricular filling (peak velocities: recipient 0.51±0.11 m/s vs donor 0.45±0.10 m/s, mean difference 0.74 m/s, 95% CI 0.23 to 1.24, p=0.009) and early septal relaxation (mean myocardial velocities: recipient -8.2±1.5 cm/s vs donor -8.9±1.2 cm/s, mean difference 0.7 cm/s, 95% CI 0.02 to 1.38, p=0.044) were found only when twins with right heart disease were included.

CONCLUSIONS

Despite severe prenatal cardiac involvement, childhood cardiac function is normal in the majority of surviving donors and recipients after successful LC of severe TTTS. This underlines the favourable impact of intrauterine LC on postnatal cardiovascular performance.

Evaluation of the right ventricular function in pneumoconiosis patients using volume-time curves obtained by real-time three-dimensional echocardiography

The study was aimed to evaluate the right ventricular function in pneumoconiosis patients by real-time three-dimensional echocardiography. A total of 80 individuals including 44 consecutive pneumoconiosis patients and 36 age- and gender-matched healthy volunteers as controls were prospectively recruited for the study. All the patients underwent two- and three-dimensional echocardiography. Measurements of the right ventricle included tricuspid regurgitation pressure (TRPG), anterior and posterior wall thickness and range of motion (TH1, TH2, M1, M2), right end-diastolic volume and end-systolic volume. The right ventricular ejection fraction (RVEF) was also calculated. The RVEF of healthy volunteers ranged from 50 to 78 %, whereas that of the pneumoconiosis patients varied from 29 to 73 %. An increase in TRPG caused a significant (p = 0.006) decrease in RVEF (by 77.3 %), suggesting the two variables were negatively correlated (r = -0.643, p < 0.01). In comparison with normal, the volume-time curves of the pneumoconiosis patients showed a lower trough. Use of real-time three-dimensional echocardiography provides with added clinical information needed to evaluate right ventricular function in pneumoconiosis patients.

Diastolic dysfunction in women with signs and symptoms of ischemia in the absence of obstructive coronary artery disease: a hypothesis-generating study

BACKGROUND

Angina, in the absence of obstructive coronary artery disease, is more common in women, is associated with adverse cardiovascular morbidity and mortality, and is a major burden to the healthcare system. Although advancements have been made to understand the mechanistic underpinning of this disease, the functional consequence remains unclear.

METHODS AND RESULTS

Cardiac magnetic resonance imaging was performed to assess left ventricular function in 20 women with signs and symptoms of ischemia, but no obstructive coronary artery disease (cases), and 15 age- and body mass index-matched reference controls. Functional imaging included standard cinematic imaging to assess left ventricular morphology and global function, along with tissue tagging to assess left ventricular tissue deformation. Systolic function was preserved in both cases and controls, with no differences in ejection fraction (mean±SE: 63.1±8% versus 65±2%), circumferential strain (-20.7±0.6% versus -21.9±0.5%), or systolic circumferential strain rate (-105.9±6.1% versus -109.0±3.8% per second). In contrast, we observed significant differences between cases and controls in diastolic function, as demonstrated by reductions in both diastolic circumferential strain rate (153.8±8.9% versus 191.4±8.9% per second; P<0.05) and peak rate of left ventricular untwisting (-99.4±8.0° versus -129.4±12.8° per second; P<0.05).

CONCLUSIONS

Diastolic function is impaired in women with signs and symptoms of ischemia in the absence of coronary artery disease, as assessed by cardiac magnetic resonance tissue tagging. These results are hypothesis-generating. Larger studies are needed to define the exact mechanism(s) responsible and to establish viable treatment strategies.

Toward functional screening of cardioactive and cardiotoxic drugs with zebrafish in vivo using pseudodynamic three-dimensional imaging

Given the high mortality in patients with cardiovascular diseases and the life-threatening consequences of drugs with unforeseen adverse effects on hearts, a critical evaluation of the pharmacological response of cardiovascular function on model animals is important especially in the early stages of drug development. We report a proof-of-principle study to demonstrate the utility of zebrafish as an analytical platform to predict the cardiac response of new drugs or chemicals on human beings. With pseudodynamic 3D imaging, we derive individual parameters that are central to the cardiac function of zebrafish, including the ventricular stroke volume, ejection fraction, cardiac output, heart rate, diastolic filling function, and ventricular mass. We evaluate both inotropic and chronotropic responses of the heart of zebrafish treated with drugs that are commonly prescribed and possess varied known cardiac activities. We reveal deranged cardiac function of a zebrafish model of cardiomyopathy induced with a cardiotoxic drug. The cardiac function of zebrafish exhibits a pharmacological response similar to that of human beings. We compare also cardiac parameters obtained in this work with those derived with conventional 2D approximation and show that the latter tends to overestimate the cardiac parameters and produces results of greater variation. In view of the growing interest of using zebrafish in both fundamental and translational biomedical research, we envisage that our approach should benefit not only contemporary pharmaceutical development but also exploratory research such as gene, stem cell, or regenerative therapies targeting congenital or acquired heart diseases.

The impact of segmental volumetric changes on functional mitral regurgitation: a study using three-dimensional regional time-volume analysis combined with low-dose dobutamine

PURPOSE

Using transthoracic three-dimensional (3D) echo regional volume analysis combined with low-dose dobutamine to investigate the effects on regional volume, mitral configuration and functional mitral regurgitation (FMR).

METHODS

Fifty-six patients with ischemic cardiomyopathy (ICM) were included in this study. The effective regurgitant orifice area (EROA) of FMR secondary to ICM with depressed left ventricular ejection fraction was compared with mitral tenting area and coaptation height (CH) before and after low-dose dobutamine (10 μg/kg per min). Using 3-DQ software we measured and calculated regional stroke-volumes (rSV), the ratio of the rSV to the whole left ventricular stroke volume (rgSVratio) in all 17 segments and the average rgSVratio of 4 anterior-PM attached segments (rgSVratio-aver anter-PM), 4 posterior-PM attached segments (rgSVratio-aver post-PM), 8 PMs attached segments (rgSVratio-aver PMs) and all 17 segments before and after dobutamine.

RESULTS

Compared with the resting condition, the SVr and rgSVratio on the basal and mid segments of anterior, lateral, inferior, and posterior walls were increased after dobutamine infusion (P < 0.05). EROA at rest was associated with tenting area, CH and rgSVratio-aver of PMs and the reduction in EROA caused by dobutamine was associated with reductions in tenting area, CH and increases in rgSVratio-aver of PMs. Tenting area was associated with rgSVratio-aver of PMs and reduction caused by dobutamine was associated with increases in rgSVratio-aver of PMs.

CONCLUSIONS

The FMR decreasing during low-dose dobutamine is quantitatively associated with the regional LV volume change of attached PMs. Real time transthoracic three-dimensional echocardiography may provide a simple and noninvasive approach to assess regional LV time-volume characteristic during FMR.

Effects of weight loss on myocardial energetics and diastolic function in obesity

A reduced myocardial phosphocreatine/adenosine triphosphate (PCr/ATP) ratio is linked to both diastolic dysfunction and heart failure. Although obesity is well known to cause diastolic dysfunction a link to impaired cardiac energetics has only recently been established. We assessed whether or not long-term weight loss in obesity, which is known to reduce mortality, is accompanied by both improved cardiac energetics and diastolic function. Normal weight (BMI 22 ± 2; n = 18) and obese subjects (BMI 34 ± 4; n = 13) underwent cine-MRI (1.5 Tesla) to determine left ventricular diastolic function using volume-time curve analysis, and (31)P-MR spectroscopy (3 Tesla) to assess cardiac energetics (PCr/ATP ratio). Obese subjects (n = 13) underwent repeat assessment after 1 year of supervised weight loss. Obesity, in the absence of identifiable cardiovascular risk factors, was associated with significantly impaired myocardial high energy phosphate metabolism (PCr/ATP ratio, normal; 2.03 ± 0.27 vs. obese; 1.58 ± 0.47, p = 0.002) and significantly lower peak diastolic filling rate (normal; 4.8 ± 0.8 vs. obese; 3.8 ± 0.7 EDV/s, p = 0.01). Weight loss (on average 9 kg, 55% excess weight) over 1 year resulted in a 24% increase in PCr/ATP ratio (p = 0.01) and an 18% improvement in peak diastolic filling rate (p = 0.01). Myocardial PCr/ATP ratio remained positively correlated with peak diastolic filling rate after weight loss (r = 0.63, p = 0.02). In obesity, weight loss improves impaired cardiac energetics and myocardial relaxation. Improved myocardial energetics appear to play a key role in diastolic functional recovery accompanying weight loss.

High-resolution cine MRI with TGRAPPA for fast assessment of left ventricular function at 3 Tesla

PURPOSE

To implement and evaluate the accuracy of multislice dual-breath hold cine MR for analysis of global systolic and diastolic left ventricular function at 3T.

MATERIALS AND METHODS

25 patients referred to cardiac MR underwent cine imaging at 3T (MAGNETOM Verio) using prospective triggered SSFP (TR 3.1 ms; TE 1.4 ms; FA 60°). Analysis of LV function was performed using a standard non-accelerated single-slice approach (STD) with multiple breath-holds and an accelerated multi-slice technique (TGRAPPA; R=4) encompassing the ventricles with 5 slices/breath-hold. Parameters of spatial and temporal resolution were kept identical (pixel: 1.9 × 2.5 mm(2); temporal resolution: 47 ms). Data of both acquisition techniques were analyzed by two readers using semiautomatic algorithms (syngoARGUS) with respect to EDV, ESV, EF, myocardial mass (MM), peak filling rate (PFR) and peak ejection rate (PER) including assessment of interobserver agreement.

RESULTS

Volumetric results of the TGRAPPA approach did not show significant differences to the STD approach for left ventricular ejection fraction (62.3 ± 10.6 vs. 61.0 ± 8.4, P=0.2), end-diastolic volume (135.8 ± 47.5 vs. 130.8 ± 46.4, P=0.07), endsystolic volume (53.0 ± 29.7 vs. 53.1 ± 32.7, P=0.99) and myocardial mass (114.2 ± 32.5 vs. 114.6±30.6, P=0.9). Moreover, a comparison of peak ejection rate (601.3 ± 190.2 vs. 590.8 ± 218.2, P=0.8) and peak filling rate (535.1±191.2 vs. 535.4 ± 210.7, P=0.99) did not reveal significant differences between the two groups. Limits in interobserver agreement were low for all systolic and diastolic parameters in both groups (P ≥ 0.05). Total acquisition time for STD was 273 ± 124 s and 34 ± 5 s for TGRAPPA (P ≤ 0.001). Evaluation time for standard and multislice approach was equal (10.8 ± 1.4 vs. 9.8 ± 2.1 min; P=0.08).

Current clinical applications of transthoracic three-dimensional echocardiography

The advent of three-dimensional echocardiography (3DE) has significantly improved the impact of non-invasive imaging on our understanding and management of cardiac diseases in clinical practice. Transthoracic 3DE enables an easier, more accurate and reproducible interpretation of the complex cardiac anatomy, overcoming the intrinsic limitations of conventional echocardiography. The availability of unprecedented views of cardiac structures from any perspective in the beating heart provides valuable clinical information and new levels of confidence in diagnosing heart disease. One major advantage of the third dimension is the improvement in the accuracy and reproducibility of chamber volume measurement by eliminating geometric assumptions and errors caused by foreshortened views. Another benefit of 3DE is the realistic en face views of heart valves, enabling a better appreciation of the severity and mechanisms of valve diseases in a unique, noninvasive manner. The purpose of this review is to provide readers with an update on the current clinical applications of transthoracic 3DE, emphasizing the incremental benefits of 3DE over conventional two-dimensional echocardiography.

Assessment of recanalization of chronic total occlusions on left ventricular function in patients with or without previous myocardial infarction by real-time three-dimensional echocardiography

The changes of left ventricular ejection fraction (LVEF) were assessed after successful recanalization of chronic total occlusions (CTO) with or without previous myocardial infarction (MI) by real-time three-dimensional echocardiography (RT3DE). 32 patients with a successfully recanalyzed CTO were included in the present prospective study. The patients were divided into group 1 without previous MI and group 2 with previous MI in the territories of total occlusion vessel that was recanalized. In addition, there was a subgroup composed of 14 patients with collateral flow or retrograde flow in group 2. In all patients, LVEF was determined by RT3DE at baseline and after 6 weeks. In group 1, the evolution of LVEF increased significantly from 59.9 ± 7.2-67.5 ± 8.7% (P < 0.05). In group 2, the evolution of LVEF increased from 48.6 ± 6.1-50.1 ± 6.4%, however, it was without statistic significance (P > 0.05). The evolution of LVEF increased from 46.8 ± 7.1-53.0 ± 7.2% (P < 0.05) in the subgroup of group 2. Left ventricular function in patients with CTO can be feasibility and actually evaluated by RT3DE. The influence of recanalization of CTO on the improvement of left ventricular function was different between MI and non-MI patients. The left ventricular function did not improve in MI patients, but improved significantly in the patients having rich collateral circulation.

Real time three-dimensional stress echocardiography: a new approach for assessing diastolic function

OBJECTIVE

To assess the feasibility of utilizing real time three-dimensional echocardiography (RT3DE) for assessment of diastolic function during stress.

METHODS

Rest and stress volumes were acquired in 24 patients and parameters of diastolic function-peak ventricular filling rate (PFR) and time to peak filling rate (TPFR)-were calculated.

RESULTS

Calculation of diastolic parameters was feasible in all patients. Resting PFR correlated with end-diastolic (EDV) and stroke volumes and inversely with TPFR (r = 0.53, 0.66, -0.5). With stress, PFR increased by 93% and TPFR decreased by 23% (P < 0.001). Stress PFR correlated with stress heart rate, EDV and stroke volume (r = 0.52, 0.50, 0.62) while TPFR correlated inversely with heart rate (r =-0.71). The change in PFR with stress correlated with the change in stroke volume (r = 0.42), while the change in TPFR correlated with the change in end-systolic volume (ESV) (r = 0.43) and inversely with the change in diastolic blood pressure (r =-0.41). Rest and stress PFR and TPFR are independent of age, gender and blood pressure and the change in PFR is independent of stress heart rate or blood pressure. E/E' correlated with stress TPFR (r = 0.72) and change in TPFR (r = 0.67) and inversely with change in PFR (r =-0.67).

CONCLUSIONS

RT3DE can assess diastolic function during stress by detecting changes in PFR and TPFR, independent of gender, age, and blood pressure. The changes in these parameters with stress are influenced by baseline filling pressures. Larger studies are required to validate the clinical significance of these observations.

Left atrial volume by real-time three-dimensional echocardiography: validation by 64-slice multidetector computed tomography

BACKGROUND

Left atrial (LA) enlargement has been acknowledged as a significant predictor of cardiovascular morbidity and mortality.

METHODS

To evaluate the accuracy of two-dimensional and three-dimensional echocardiography for determining LA volume, LA volume measurements by echocardiography were compared with those measured by 64-slice multidetector computed tomography (MDCT) as a reference standard.

RESULTS

Fifty-seven consecutive patients (mean age, 66 ± 11 years; 59% men) referred to echocardiography and MDCT on the same day were prospectively evaluated. LA volume by three-dimensional echocardiography was correlated closely with that by MDCT (r = 0.95, P < .0001), with 8% underestimation. LA volume by two-dimensional echocardiography was correlated less well with that measured by MDCT (r = 0.86, P < .0001) and consistently underestimated LA volume by 19%, particularly as the left atrium enlarged.

CONCLUSIONS

LA volume assessment by three-dimensional echocardiography was correlated closely with that measured by MDCT, albeit with an 8% underestimation. Three-dimensional echocardiography is a feasible noninvasive method to evaluate LA volume.

Diastolic dysfunction: improved understanding using emerging imaging techniques

Diastolic heart failure is increasing in prevalence. Although the pathophysiology is incompletely understood and current therapeutic strategies are limited, identification of diastolic dysfunction is important. We review the role of contemporary techniques with echocardiography and cardiac magnetic resonance imaging (CMRI) in the assessment of diastolic dysfunction. Cardiac catheterization is the criterion standard for demonstrating impaired relaxation and filling by making direct measurements; however, echocardiography has replaced it as the most clinically used tool. By evaluating mitral inflow pulsed-wave Doppler with and without the Valsalva maneuver, isovolumetric relaxation time, pulmonary venous flow Doppler, color M-mode velocity propagation, tissue Doppler imaging, and speckle tracking, echocardiography is considered an accurate method for diagnosis and grading diastolic dysfunction. Evaluation of diastolic function can also be performed by CMRI. Mitral valve inflow velocities, early deceleration time, and pulmonary vein flow velocities are diastolic parameters that can be measured by phase-contrast CMRI. Cardiac magnetic resonance imaging steady-state gradient echo can evaluate functional dimensions for time-volume curves; and myocardial tagging can assess ventricular diastolic "untwisting," which may be important for improved pathophysiologic understanding. Studies have compared echocardiography and CMRI for diagnosing diastolic dysfunction in small patient groups with similar results. Cardiac magnetic resonance imaging can now provide clinically relevant data regarding the underlying cause of diastolic dysfunction and offers promise to gain mechanistic insights for therapeutic strategy development and clinical trial planning.

Role of three-dimensional echocardiography in breast cancer: comparison with two-dimensional echocardiography, multiple-gated acquisition scans, and cardiac magnetic resonance imaging

PURPOSE

In patients with breast cancer, the administration of doxorubicin and trastuzumab is associated with an increased risk of cardiotoxicity. Although multiple-gated acquisition (MUGA) scans and two-dimensional transthoracic echocardiography (TTE) are conventional methods for baseline and serial assessment of left ventricular ejection fraction (LVEF) in these patients, little is known about the use of real-time three-dimensional TTE (RT3D TTE) in this clinical setting. The aim of this study was to assess the accuracy of MUGA, 2D TTE, and RT3D TTE for determining LVEF in comparison to cardiac magnetic resonance imaging (CMR).

METHODS

Between 2007 and 2009 inclusive, 50 female patients with human epidermal growth factor receptor 2-positive breast cancer received adjuvant trastuzumab after doxorubicin. Serial MUGA, 2D TTE, RT3D TTE, and CMR were performed at baseline, 6, and 12 months after the initiation of trastuzumab.

RESULTS

A comparison of left ventricular end diastolic volume (LVEDV) demonstrated a modest correlation between 2D TTE and CMR (r = 0.64 at baseline; r = 0.69 at 12 months, respectively). A comparison of LVEDV between RT3D TTE and CMR demonstrated a stronger correlation (r = 0.87 at baseline; r = 0.95 at 12 months, respectively). Although 2D TTE demonstrated a weak correlation with CMR for LVEF assessment (r = 0.31 at baseline, r = 0.42 at 12 months, respectively), both RT3D TTE and MUGA showed a strong correlation when compared with CMR (r = 0.91 at baseline; r = 0.90 at 12 months, respectively).

CONCLUSION

As compared with conventional MUGA, RT3D TTE is a feasible, accurate, and reproducible alternate imaging modality for the serial monitoring of LVEF in patients with breast cancer.

Measurements of changes in left ventricular volume, strain, and twist during isovolumic relaxation using MRI

Left ventricular (LV) active relaxation begins before aortic valve closure and is largely completed during isovolumic relaxation (IVR), before mitral valve opening. During IVR, despite closed mitral and aortic valves, indirect assessments of LV volume have suggested volume increases during this period. The aim of this study is to measure LV volume throughout IVR and to determine the sources of any volume changes. For 10 healthy individuals (26.0 ± 3.8 yr), magnetic resonance imaging was used to measure time courses of LV volume, principal myocardial strains (circumferential, longitudinal, radial), and LV twist. Mitral leaflet motion was observed using echocardiography. During IVR, LV volume measurements showed an apparent increase of 4.6 ± 1.5 ml (5.0 ± 2.0% of the early filling volume change), the LV untwisted by 4.5 ± 1.9° (36.6 ± 18.0% of peak systolic twist), and changes in circumferential, longitudinal, and radial strains were +0.87 ± 0.64%, +0.93 ± 0.57%, and −1.46 ± 1.66% (4.2 ± 3.3%, 5.9 ± 3.3%, and 5.3 ± 7.5% of peak systolic strains), respectively. The apparent changes in volume correlated ( P < 0.01) with changes in circumferential, longitudinal, and radial strains ( r = 0.86, 0.69, and −0.37, respectively) and untwisting ( r = 0.83). The closed mitral valve leaflets were observed to descend into the LV throughout IVR in all subjects in apical four- and three-chamber and parasternal long-axis views by 6.0 ± 3.3, 5.1 ± 2.4, and 2.1 ± 5.0 mm, respectively. In conclusion, LV relaxation during IVR is associated with changes in principal strains and untwisting, which are all correlated with an apparent increase in LV volume. Since closed mitral and aortic valves ensure true isovolumic conditions, the apparent volume change likely reflects expansion of the LV myocardium and the inward bowing of the closed mitral leaflets toward the LV interior.

Measurement of left ventricular ejection fraction by real time 3D echocardiography in patients with severe systolic dysfunction: comparison with radionuclide angiography

AIM

Measurement of left ventricular ejection fraction (LVEF) using real time 3D echocardiography (3DE) has been performed in subjects with preserved or modestly reduced systolic function. Our aim was to evaluate this technique in the subset of patients with severe systolic dysfunction.

METHODS AND RESULTS

Consecutive patients with LVEF less than 0.35 at two-dimensional echocardiography were included. LVEF obtained by 3DE was compared to the value measured by radionuclide angiography (RNA). Real time full-volume 3DE was performed, with offline semiautomated measurement of LVEF using dedicated software (Cardioview RT, Tomtec) by a single observer blinded to the results of RNA. A total of 50 patients were evaluated, of whom 38 (76%, 27 males, age 69 +/- 13 years) had a 3DE of sufficient quality for analysis. LVEF for this group was 0.21 +/- 0.07 using 3DE and 0.27 +/- 0.08 using RNA. The agreement between the two techniques was rather poor (r = 0.49; P < 0.001; 95% limits of agreements of -0.20 to 0.09). Truncation of the apex was observed in 6 of 38 (16%) patients.

CONCLUSION

In patients with severe systolic dysfunction, 3DE shows poor agreement for measurement of LVEF as compared to RNA. There may be underestimation of up to 20% in absolute terms by 3DE. Accordingly, the two methods are not interchangeable for the follow-up of LV function. A limitation of 3DE may, at least in part, be related to the incomplete incorporation of the apical region into the pyramidal image sector in patients with dilated hearts.