Left ventricular volumes and ejection fraction derived from apical two-dimensional echocardiography

Two-dimensional echocardiographic data in orthogonal apical projections were used to calculate left ventricular ejection fraction and volumes in 18 patients, 10 of whom had asynergy. The left ventricular chamber was modeled as a stack of 20 elliptical discs in order to minimize errors associated with assumptions of regular geometry. Calculations were compared to data from biplane angiography and yielded correlation coefficients of 0.91 for ejection fraction and 0.90 for volumes. The technique significantly underestimated volumes; the average ventricular volume was 161 +/- 23 ml from cineangiography and 104 +/- 25 ml from echocardiography (p < 0.001). Since this technique utilizes the most readily obtained echocardiographic views and allows for variations in ventricular architecture, its potential utility in long-term, serial evaluation of cardiac function appears promising.     

Prediction and assessment of the time-varying effective pulmonary vein area via cardiac MRI and Doppler echocardiography

Accurately estimating left atrial (LA) volume with Doppler echocardiography remains challenging. Using angiography for validation, Marino et al. (Marino P, Prioli AM, Destro G, LoSchiavo I, Golia G, and Zardini P. Am Heart J 127: 886-898, 1994) determined LA volume throughout the cardiac cycle by integrating the velocity-time integrals of Doppler transmitral and pulmonary venous flow, assuming constant mitral valve and pulmonary vein areas. However, this LA volume determination method has never been compared with three-dimensional LA volume data from cardiac MRI, the gold standard for cardiac chamber volume measurement. Previously, we determined that the effective mitral valve area is not constant but varies as a function of time. Therefore, we sought to determine whether the effective pulmonary vein area (EPVA) might be time varying as well and also assessed Marino's method for estimating LA volume. We imaged 10 normal subjects using cardiac MRI and concomitant transthoracic Doppler echocardiography. LA and left ventricular (LV) volumes were measured by MRI, transmitral and pulmonary vein flows were measured by Doppler echocardiography, and time dependence was synchronized via the electrocardiogram. LA volume, estimated using Marino's method, was compared with the MRI measurements. Differences were observed, and the discrepancy between the echocardiographic and MRI methods was used to predict EPVA as a function of time. EPVA was also directly measured from short-axis MRI images and was found to be time varying in concordance with predicted values. We conclude that because EPVA and LA volume time dependence are in phase, LA filling in systole and LV filling in diastole are both facilitated. Application to subjects in select pathophysiological states is in progress.     

Influence of left bundle branch block on left ventricular volumes, ejection fraction and regional wall motion

Background. Left ventricular volumes, ejection fraction and regional wall motion are cardiac parameters which provide valuable information for patient management in a large variety of cardiac conditions. Differences in regional wall motion are of relevance in the field of cardiac resynchronisation therapy. We quantified three-dimensional echocardiographic measurements of left ventricular volumes, ejection and regional wall motion (e.g. expressed as systolic dyssynchrony index (SDI)) in two patient cohorts: patients with normal conduction and patients with complete left bundle branch block. Methods. Thirty-five patients scheduled for routine cardiac examination underwent three-dimensional echocardiography: 23 patients with normal conduction and 12 patients with a complete left bundle branch block. Full-volume datasets were analysed and end-systolic volume (ESV), end-diastolic volume (EDV) and ejection fraction (EF) were obtained. SDI was derived from the standard deviation of the measured times to reach minimal regional volume for each of the 16 segments of the left ventricle. Results. A significant difference was observed in left ventricular volumes, ejection fraction and SDI between the two groups. Patients with complete left bundle branch block showed higher EDV (p=0.025) and ESV (p<0.01) and a lower EF (p<0.01) than patients with normal conduction. SDI is significantly higher in patients with complete left bundle branch block (p=0.004) expressing a higher amount of ventricular dyssynchrony. Intraobserver variability showed excellent correlation coefficients: r=0.99 for EDV, ESV and SDI and r=0.98 for EF. Conclusion. Three-dimensional echocardiography is a feasible and reproducible method for the quantification of left ventricular volumes, left ventricular ejection fraction and regional wall motion. Differences can be assessed between normal patients and patients with left bundle branch block. (Neth Heart J 2007;15:89-94.)     

Ventricular dimensions measured noninvasively by echocardiography in the awake dog.

A surface echocardiographic technique was employed in 37 mongrel dogs for measurement of left ventricular dimensions. Intracardiac bolus injections of dextran were used as an echo contrast material to visualize cardiac chambers, and the identification of intracardiac structures was further confirmed by postmortem examination. The left ventricle could be satisfactorily visualized from both the right and left chest, providing two transverse left ventricular diameters nearly perpendicular to each other. End-diastolic and end-systolic diameter measurements in the two separate transverse planes differed by an average of only 0.07 and 0.1 cm, respectively, and dimensional measurements were reproducible from day to day. Diastolic diameter ranged from 3.0 to 4.7 cm (mean 3.7 cm) and systolic diameter 1.9 to 3.3 cm (mean 2.6 cm). Diameter was directly related to animal weight. Stroke volume calculated from the dimension measurements correlated with stroke volume calculated from indicator-dilution curves in 16 dogs. Ejection fraction averaged 0.67 and 0.54, depending on the formula used to calculate volumes. These results indicate that surface echocardiography can be employed to evaluate left ventricular dimensions in the awake dog.     

Echocardiographic parameters and indices in the normal beagle dog.

M-mode and two-dimensional echocardiographic measurements were made from the right sternal border of 50 healthy Beagles (25 males and 25 females) approximately 7 months old. The dogs were conscious and standing during the investigation. The following parameters, in systole and diastole, were measured on the echocardiographic images: left ventricular posterior wall thickness (LVWT); intraventricular septum thickness (IST); left ventricular internal dimension (LVID); and circumference (LVC). Fractional shortening (FS) and ejection fraction (EF) were also calculated. Mean, standard deviation, range and coefficient of variation are reported for each echocardiographic parameter and for body weight. Males and females were considered separately and together. Each parameter was analysed statistically to check for differences between the sexes and for correlations with body weight. A statistically significant difference between the sexes was only observed for LVWT in systole and diastole. A linear regression with body weight was obtained only for LVID in systole and in diastole. The results show that morphofunctional cardiac homogeneity is independent of size in dogs of this breed and age.     

Effects of positive end-expiratory pressure on the right ventricle

Transmural cardiac pressures, stroke volume, right ventricular volume, and lung water content were measured in normal dogs and in dogs with oleic acid-induced pulmonary edema (PE) maintained on positive-pressure ventilation. Measurements were performed prior to and following application of 20 cmH2O positive end-expiratory pressure (PEEP). Colloid fluid was given during PEEP for ventricular volume expansion before and after the oleic acid administration. PEEP significantly increased pleural pressure and pulmonary vascular resistance but decreased right ventricular volume, stroke volume, and mean arterial pressure in both normal and PE dogs. Although the fluid infusion during PEEP raised right ventricular diastolic volumes to the pre-PEEP level, the stroke volumes did not significantly increase in either normal dogs or the PE dogs. The fluid infusion, however, significantly increased the lung water content in the PE dogs. Following discontinuation of PEEP, mean arterial pressure, cardiac output, and stroke volume significantly increased, and heart rate did not change. The failure of the stroke volume to increase despite significant right ventricular volume augmentation during PEEP indicates that positive-pressure ventilation with 20 cmH2O PEEP decreases right ventricular function.     

Clinical Results of Real-Time Ultrasonic Scanning of the Heart Using a Phased Array System

This report describes the operating characteristics and initial clinical results of a new echocardiographic system that produces real-time, high resolution, cross-sectional images of the heart. This system relies upon phased-array principles to rapidly steer and focus the ultrasound beam through the cardiac structures under investigation. A hand-held, linear array of 24 transducers is manipulated on the patient''s chest to direct the interrogating plane at various cardiac structures. Images of high line density are presented in selectable sector arcs to a maximum of 90 degrees. This imaging system has been used clinically in over 2,000 patients in the past two and one-half years. Its use in the detection of altered states of ventricular and valvular pathology has been described.     

Adaptation of human left ventricular volumes to the onset of supine exercise

The purpose of this study was to measure the changes and rates of adaptation of left ventricular volumes at the onset of exercise. Eight asymptomatic subjects, in whom intramyocardial markers had been implanted 3-6 years previously during aortocoronary bypass surgery, exercised in the supine position at a constant workload of 73.6 W for 5 min. Six also exercised first at 16.4 W, and then against a workload which progressively increased by 8.2 W every 15 s. Cardiac volumes were measured by computer assisted analysis of the motion of the implanted markers. In the constant workload test, cardiac output increased rapidly from 5.7 +/- 1 min-1 to 10.3 +/- 1.9 1 min-1 by 2 min and then increased more slowly to 10.8 +/- 2.0 1 min-1 by 5 min. The cardiac output increase was mainly due to an increase in heart rate from 68 +/- 12 beats min-1 to 120 +/- 16 beats min-1 with minimal changes in stroke volume. The time constant for the early increase in cardiac output was 45s and for heart rate, 35s. With progressively increasing workloads, there was an almost linear increase of heart rate and cardiac output, but these increased at a slower rate than during the early phase of the constant load exercise test. In conclusion: rapid changes in cardiac output during supine exercise were produced by changes in heart rate; changes in stroke volume provided minor adjustments to cardiac output; the end-diastolic volume was almost constant.     

Rapid microcomputed tomography suggests cardiac enlargement occurs during conductance catheter measurements in mice

Conductance catheters (CC) represent an established method of determining cardiac function in mice; however, the potentially detrimental effects a catheter may have on the mouse heart have never been evaluated. The present study takes advantage of rapid three-dimensional (3D) microcomputed tomography (CT) to compare simultaneously acquired micro-CT and CC measurements of left ventricular (LV) volumes in healthy and infarcted mice and to determine changes in LV volume and function associated with CC insertion. LV volumes were measured in C57BL/6 mice (10 healthy, 10 infarcted, 2% isoflurane anesthesia) using a 1.4-Fr Millar CC. 3D micro-CT images of each mouse were acquired before CC insertion as well as during catheterization. Each CT scan produced high-resolution images throughout the entire cardiac cycle in <1 min, enabling accurate volume measurements as well as direct visualization of the CC within the LV. Bland-Altman analysis demonstrated that CC measurements underestimate volume compared with CT measurements in both healthy [bias of -18.4 and -28.9 μl for end-systolic (ESV) and end-diastolic volume (EDV), respectively] and infarcted mice (ESV = -51.6 μl and EDV = -71.7 μl); underestimation was attributed to the off-center placement of the catheter. Individual evaluation of each heart revealed LV dilation following CC insertion in 40% of mice in each group. No change in ejection fraction was observed, suggesting the enlargement was caused by volume overload associated with disruption of the papillary muscles or chords. The enlargement witnessed was not significant; however, the results suggest the potential for CC insertion to detrimentally affect mouse myocardium, necessitating further investigation.     

In-vivo estimations of the nonlinear pressure-volume relationship of the aorta and instantaneous left ventricular volume

A method is presented in this paper for the in-vivo estimation of the nonlinear pressure-volume relationship of the human aorta. The method is based on nonlinear elastic reservoir theory and utilizes clinical data that can be obtained with a high degree of accuracy, namely stroke volume, end diastolic ventricular volume and aortic pressure trace data. The computational procedure is described and then carried out for six cardiac patients. A method for the estimation of instantaneous left ventricular volume during the ejection period based on the considered nonlinear elastic reservoir theory is also presented. The method is applied for the six cardiac patients cited and the results compared with those obtained for the same subjects by a method of estimation based on linear elastic reservoir theory described in a previous paper by the author (1969).     

Assessment of left ventricular ejection fraction in patients eligible for ICD therapy: Discrepancy between cardiac magnetic resonance imaging and 2D echocardiography

Objective

Implantable cardioverter defibrillators (ICD) and cardiac resynchronisation therapy (CRT) have substantially improved the survival of patients with cardiomyopathy. Eligibility for this therapy requires a left ventricular ejection fraction (LVEF) <35 %. This is largely based on studies using echocardiography. Cardiac magnetic resonance imaging (CMR) is increasingly utilised for LVEF assessment, but several studies have shown differences between LVEF assessed by CMR and echocardiography. The present study compared LVEF assessment by CMR and echocardiography in a heart failure population and evaluated effects on eligibility for device therapy.

Methods

152 patients (106 male, mean age 65.5 ± 9.9 years) referred for device therapy were included. During evaluation of eligibility they underwent both CMR and echocardiographic LVEF assessment. CMR volumes were computed from a stack of short-axis images. Echocardiographic volumes were computed using Simpson’s biplane method.

Results

The study population demonstrated an underestimation of end-diastolic volume (EDV) and end-systolic volume (ESV) by echocardiography of 71 ± 53 ml (mean ± SD) and 70 ± 49 ml, respectively. This resulted in an overestimation of LVEF of 6.6 ± 8.3 % by echocardiography compared with CMR (echocardiographic LVEF 31.5 ± 8.7 % and CMR LVEF 24.9 ± 9.6 %). 28 % of patients had opposing outcomes of eligibility for cardiac device therapy depending on the imaging modality used.

Conclusion

We found EDV and ESV to be underestimated by echocardiography, and LVEF assessed by CMR to be significantly smaller than by echocardiography. Applying an LVEF cut-off value of 35 %, CMR would significantly increase the number of patients eligible for device implantation. Therefore, LVEF cut-off values might need reassessment when using CMR.     

Assessment of right and left ventricular function in healthy mice by blood-pool pinhole gated SPECT

The feasibility of blood-pool pinhole ECG gated SPECT was investigated in healthy mice to assess right and left ventricular function analysis. Anaesthetized (isoflurane 1-1.5%) adult CD1 mice (n=11) were analyzed after intravenous administration of 0.2 ml of 550 MBq of (99m)Tc human albumin. For blood-pool gated SPECT imaging, 48 ventral step and shoot projections with eight time bins per RR over 180 degrees with 64x64 word images were acquired with a small animal gamma camera equipped with a pinhole collimator of 12 cm in focal length and 1.5 mm in diameter. For appropriate segmentation of right and left ventricular volumes, a 4D Fourier analysis was performed after reconstruction and reorientation of blood-pool images with a voxel size of 0.55x0.55x0.55 mm(3). Average right and left ejection fractions were respectively 52+/-4.7% and 65+/-5.2%. Right end diastolic and end systolic volumes were significantly higher compared with the corresponding left ventricular volumes (P<0.0001 each). A linear correlation between right and left stroke volumes (r=0.9, P<0.0001) was obtained and right and left cardiac outputs were not significantly different 14.2+/-1.9 and 14.1+/-2 ml/min, respectively. To cite this article: C. Goetz et al., C. R. Biologies 331 (2008).     

Pulmonary Haemodynamics in Sickle Cell Disease Are Driven Predominantly by a High-Output State Rather Than Elevated Pulmonary Vascular Resistance: A Prospective 3-Dimensional Echocardiography/Doppler Study

Aims

Patients with sickle cell disease have significant morbidity and mortality. Pulmonary hypertension is suggested to be an important contributor but its nature and severity in these patients and how best to non-invasively assess it are controversial. We hypothesised that a high-output state rather than primary pulmonary vascular pathology may be the major abnormality in sickle cell disease. This study aimed to evaluate the characteristics and severity of pulmonary hypertension in patients with sickle cell disease using detailed echocardiography.

Methods and Results

We undertook a prospective study in 122 consecutive stable outpatients with sickle cell disease and 30 age, gender and ethnicity-matched healthy controls. Echocardiographic evaluation included 3D ventricular volumes, sphericity, tissue Doppler, and non-invasive estimation of pulmonary vascular resistance. 36% of patients had a tricuspid regurgitant velocity ≥2.5 m.s^-1 but only 2% had elevated pulmonary vascular resistance and the prevalence of right ventricular dysfunction was very low. Patients with raised tricuspid regurgitant velocity had significantly elevated biventricular volumes and globular left ventricular remodelling, related primarily to anaemia. In a subgroup of patients who underwent cardiac catheterization, invasive pulmonary haemodynamics confirmed the echocardiographic findings.

Conclusions

Elevated cardiac output and left ventricular volume overload secondary to chronic anaemia may be the dominant factor responsible for abnormal cardiopulmonary haemodynamics in patients with sickle cell disease. 3D echocardiography with non-invasive estimation of pulmonary vascular resistance represents a valuable approach for initial evaluation of cardiopulmonary haemodynamics in sickle cell disease.     

Echocardiographic measurement of cardiac output in rats

The systematic evaluation of different transthoracic echocardiographic (TTE) methods to determine cardiac output (CO) and the effect of changes in intravascular volume on echocardiographically determined indexes of cardiovascular structure in the rat has not been documented. With the use of 11 Wistar rats, simultaneous echocardiographic and thermodilution measurements of CO were compared at baseline and after blood withdrawal or transfusion at 43 different levels of intravascular volume and using 10 different echocardiographic approaches. The best correlation (r = 0.93; P < 0.0001), least bias (-3 ml/min), and best precision (16 ml/min) between thermodilution and echocardiographic methods were obtained at the level of aortic annulus using pulsed Doppler. In conclusion, CO could be accurately assessed in rats using TTE and pulsed Doppler at the level of the aortic annulus. This annulus was demonstrated to remain stable, but pulmonary annulus, thoracic aorta, mitral valve, and left ventricular diameters were found to be more modifiable during volumic changes.     

Volumetric quantification of intracranial and ventricular volume following cranial vault remodeling: a preliminary report

This preliminary study documents preoperative and postoperative changes in cerebral tissue as well as intracranial and ventricular volume in patients who underwent cranial vault remodeling for craniosynostosis. The documentation and calculations were provided from CT data according to a craniofacial protocol. Three-dimensional images were then obtained of the preoperative and postoperative skulls and cerebral tissues. From these data, comparisons of preoperative and postoperative volumes of the cerebral tissue and ventricles could be examined. In one case, a frontal bone advancement combined with anterior cranial vault remodeling was associated with an increase in intracranial volume of 110 cc (8 percent) and a ventricular volume increase of 112 percent. The reported technique should allow more complete evaluation of the preoperative pathology and documentation and prediction of the projected intracranial and ventricular volume changes.     

Echocardiographic chamber quantification in a healthy Dutch population

Aim

For accurate interpretation of echocardiographic measurements normative data are required, which are provided by guidelines. For this article, the hypothesis was that these cannot be extrapolated to the Dutch population, since in Dutch clinical practice often higher values are found, which may not be pathological but physiological. Therefore this study aimed to 1) obtain and propose normative values for cardiac chamber quantification in a healthy Dutch population and 2) determine influences of baseline characteristics on these measurements.

Methods

Prospectively recruited healthy subjects, aged 20–72 years (at least 28 subjects per age decade, equally distributed for gender) underwent physical examination and 2D and 3D echocardiography. Both ventricles and atria were assessed and volumes were calculated.

Results

147 subjects were included (age 44 ± 14 years, 50% female). Overall, feasibility was good for both linear and volumetric measurements. Linear and volumetric parameters were consistently higher than current guidelines recommend, while functional parameters were in line with the guidelines. This was more so in the older population. 3D volumes were higher than 2D volumes. Gender dependency was seen in all body surface area (BSA) corrected volumes and with increasing age, ejection fractions decreased.

Conclusion

This study provides 2D and 3D echocardiographic reference ranges for both ventricles and atria derived from a healthy Dutch population. BSA indexed volumes are gender-dependent, age did not influence ventricular volumes and a rise in blood pressure was independently associated with increased right ventricular volumes. The higher volumes found may be indicative for the Dutch population being the tallest in the world.

     

Relationship of pulmonary vein flow to left ventricular short-axis epicardial displacement in diastole: model-based prediction with in vivo validation

Previous studies in healthy humans have established that the (approximately 850 ml) volume enclosed by the pericardial sac is nearly constant over the cardiac cycle, exhibiting a transient approximately 5% decrease (approximately 40 ml) from end diastole to end systole. This volume decrease manifests as a "crescent" at the ventricular free wall level when short-axis MRI images of the epicardial surface acquired at end systole and end diastole are superimposed. On the basis of the (near) constant-volume property of the four-chambered heart, the volume decrease ("crescent effect") must be restored during subsequent early diastolic filling via the left atrial conduit volume. Therefore, volume conservation-based modeling predicts that pulmonary venous (PV) Doppler D-wave volume must be causally related to the radial displacement of the epicardium (Delta) (i.e., magnitude of "crescent effect" in the radial direction). We measured Delta from M-mode echocardiographic images and measured D-wave velocity-time integral (VTI) from Doppler PV flow of the right superior PV in 11 subjects with catheterization-determined normal physiology. In accordance with model prediction, high correlation was observed between Delta and D-wave VTI (r=0.86) and early D-wave VTI measured to peak D-wave velocity (r=0.84). Furthermore, selected subjects with various pathological conditions had values of Delta that differed significantly. These observations demonstrate the volume conservation-based causal relationship between radial pericardial displacement of the left ventricle and the PV D-wave-generated filling volume in healthy subjects as well as the potential role of the M-mode echo-derived radial epicardial displacement index Delta as a regional (radial) parameter of diastolic function.     

Effect of exercise on blood flow through the aortic valve: a combined clinical and numerical study

The aim of this study was to measure the cardiac output and stroke volume for a healthy subject by coupling an echocardiogram Doppler (echo-Doppler) method with a fluid–structure interaction (FSI) simulation at rest and during exercise. Blood flow through aortic valve was measured by Doppler flow echocardiography. Aortic valve geometry was calculated by echocardiographic imaging. An FSI simulation was performed, using an arbitrary Lagrangian–Eulerian mesh. Boundary conditions were defined by pressure loads on ventricular and aortic sides. Pressure loads applied brachial pressures with (stage 1) and without (stage 2) differences between brachial, central and left ventricular pressures. FSI results for cardiac output were 15.4% lower than Doppler results for stage 1 (r = 0.999). This difference increased to 22.3% for stage 2. FSI results for stroke volume were undervalued by 15.3% when compared to Doppler results at stage 1 and 26.2% at stage 2 (r = 0.94). The predicted mean backflow of blood was 4.6%. Our results show that numerical methods can be combined with clinical measurements to provide good estimates of patient-specific cardiac output and stroke volume at different heart rates.     

Surface:volume relationship in cardiac myocytes studied with confocal microscopy and membrane capacitance measurements: species-dependence and developmental effects.

The quantitative analysis of the contribution of ion fluxes through membrane channels to changes of intracellular ion concentrations would benefit from the exact knowledge of the cell volume. It would allow direct correlation of ionic current measurements with simultaneous measurements of ion concentrations in individual cells. Because of various limitations of conventional light microscopy a simple method for accurate cell volume determination is lacking. We have combined the optical sectioning capabilities of fluorescence laser scanning confocal microscopy and the whole-cell patch-clamp technique to study the correlation between cell volume and membrane capacitance. Single cardiac myocytes loaded with the fluorescent dye calcein were optically sectioned to produce a series of confocal images. The volume of cardiac myocytes of three different mammalian species was determined by three-dimensional volume rendering of the confocal images. The calculated cell volumes were 30.4 +/- 7.3 pl (mean +/- SD) in rabbits (n = 28), 30.9 +/- 9.0 pl in ferrets (n = 23), and 34.4 +/- 7.0 pl in rats (n = 21), respectively. There was a positive linear correlation between membrane capacitance and cell volume in each animal species. The capacitance-volume ratios were significantly different among species (4.58 +/- 0.45 pF/pl in rabbit, 5.39 +/- 0.57 pF/pl in ferret, and 8.44 +/- 1.35 pF/pl in rat). Furthermore, the capacitance-volume ratio was dependent on the developmental stage (8.88 +/- 1.14 pF/pl in 6-month-old rats versus 6.76 +/- 0.62 pF/pl in 3-month-old rats). The data suggest that the ratio of surface area:volume of cardiac myocytes undergoes significant developmental changes and differs among mammalian species. We further established that the easily measurable parameters of cell membrane capacitance or the product of cell length and width provide reliable but species-dependent estimates for the volume of individual cells.