Estimation Of Left Ventricular Mass Research Articles

Left ventricular mass in patients with heart failure.

To assess left ventricular mass in patients with heart failure and its correlations with other clinical variables and prognosis. The study comprised 587 patients aged from 13.8 years to 68.9 years, 461 (78.5%) being males and 126 (21.5%) females. Left ventricular mass was estimated by using M-mode echocardiography and was indexed by height. The left ventricular mass index ranged from 35.3 g/m to 333.5 g/m and increased with age. The left ventricular mass index was greater in males (mean, 175.7 g/m) than in females (mean, 165.7 g/m). The left ventricular mass index was greater in patients with hypertensive cardiomyopathy (mean of 188.1 g/m), with idiopathic dilated cardiomyopathy (mean, 177.7 g/m) and with cardiomyopathies of other etiologies (mean, 175.1 g/m) than in patients with chagasic (mean, 164.3 g/m) or ischemic (mean, 162 g/m) cardiomyopathy. The left ventricular mass index in patients with heart failure showed a correlation with age, sex, etiology, and left atrial diameter. The correlation with left ventricular ejection fraction was negative: the increase in the left ventricular mass index was associated with a reduction in ejection fraction. The relative risk of death was 1.22 for each 50-g/m increase in the left ventricular mass index. The estimate of left ventricular mass may contribute to the prognostic assessment of patients with heart failure.

Limited utility of the subcostal view for the echocardiographic evaluation of left ventricular mass in epidemiological studies of older persons

Background: Epidemiological estimates of left ventricular mass are based on echocardiographic imaging from the parasternal view, which is often unavailable in subjects with obesity or lung disease. This study was undertaken to assess whether the subcostal view is a valid alternative to estimate left ventricular mass in an unselected older population. Methods: In a cross-sectional study of all the residents in Dicomano, Italy, aged ≥65 years, echocardiography was performed with a systematic attempt to obtain both the parastermal and the subcostal views. Results: The parasternal view was missing in 73/614 participants, 48 of whom were imaged from the subcostal view. In participants imaged from both views, the subcostal view underestimated left ventricular cavity dimension and, consequently, left ventricular mass [79.7 (1.3) vs. 93.3 (1.5) g/m 2; p<0.001]. Furthermore, the subcostal view was only 25% sensitive for the diagnosis of hypertrophy. Several multivariate regression models, developed in an equation development subgroup and tested in a validation subgroup, failed to correct the prediction of left ventricular mass based on measures taken from the subcostal view, also after inclusion of demographic, anthropometric, and spirometric covariates. Conclusions: In unselected older persons, the subcostal view does not improve the accuracy of echocardiographic estimation of left ventricular mass, which remains biased in epidemiological studies.

Validation Study of Normogram For the Clinical Determination of Left Venrtricular Mass(Lvm) From M-Mode Echocardiographic Measurements in Hypertensive Heart Disease

In a study of 70 newly diagnosed hypertensive at the University of Maiduguri Teaching Hospital over a six month period, echocardiography detected increased left ventricular weight (= 225g) in 31 patients representing 44.3%. When compared with the rapid assessment of the estimation of Left Ventricular Mass (LVM) with a normogram for the clinical determination of LVM using M-mode measurement, the following indices were found: sensitivity of 61.3%, specificity of 97.4% and accuracy of 81.4%. These fairly good indices closely estimate the presence of LVM in patient with hypertensive heart disease (HHD). We therefore recommend the use of the normogram for centres without automated machines and busy specialist clinics for rapid estimation of LVM. This will improve the optimal management we render to our patients. Nig. Medical Practitioner Vol. 45(1/2) 2004: 6-8

Accuracy of One? and Two?Dimensional Algorithms with Optimal Image Plane Position for the Estimation of Left Ventricular Mass: A Comparative Study Using Magnetic Resonance Imaging

The commonly recommended one-dimensional (ID) and two-dimensional (2D) algorithms for left ventricular (LV) mass calculation are limited by assumptions about ventricular geometry and image plane position. To assess the accuracy of these algorithms after eliminating errors associated with image plane position, LV mass was calculated from high quality cardiovascular magnetic resonance imaging (CMR) data sets using ID (modified cube formula; MCF) and 2D algorithms [area-length (AL) and truncated ellipsoid (TE) methods], and the summation of slices (SS) method as reference technique in 25 patients with LV aneurysms, 15 patients with hypertrophic cardiomyopathy, and 10 healthy subjects. Each algorithm in each group overestimated LV mass compared to SS (p <0.05 and p<0.001). In each patient group, the smallest bias to the reference method was observed for the TE algorithm (p<0.001 vs. MCF and p < 0.05 vs. AL). The LV mass interval encompassing the limits of agreement was 120-220 g for MCF, 100-148 g for AL, and 80-136 g for TE. The interstudy reproducibility of the SS technique for the assessment of LV mass was superior compared to the ID and 2D algorithms. We conclude that despite the use of optimized image plane position ID and 2D algorithms are inaccurate for calculation of LV mass in ventricles with normal and distorted LV geometry. Thus, 3D imaging techniques, such as CMR, should be preferred when assessing LV mass.

A comparison of left ventricular mass between two-dimensional echocardiography, using fundamental and tissue harmonic imaging, and cardiac MRI in patients with hypertension

Purpose: To compare left ventricular mass (LVM) as measured by two-dimensional (2D) echocardiography using two different calculation methods: truncated ellipse (TE) and area length (AL), in both fundamental and tissue harmonic imaging frequencies, to LVM as measured by, the current gold standard, cardiac magnetic resonance imaging (MRI). Turbo gradient echo (TGE) pulse sequence was utilized for MRI. Materials and methods: Thirty-two subjects with history of hypertension were recruited. The images were acquired, contours were traced and the LVM was calculated for all four different echocardiography methods as well as for the cardiac MRI method. The intra-observer variabilities were calculated. The four different echocardiography methods were compared to cardiac MRI using the method described by Bland and Altman. Results: Twenty-five subjects had adequate paired data sets. The mean LVM as measured by cardiac MRI was 162±55 g and for the four different echocardiography methods were: fundamental AL 165±55 g, harmonic AL 168±53 g, fundamental TE 148±50 g, harmonic TE 149±45 g. The intra-observer variability for cardiac MRI method, expressed as bias ± 1 standard deviation of the difference (S.D.D.), was 2.3±9.2 g and for the four different echocardiography methods were: fundamental TE 0.4±26.8 g, fundamental AL 0.6±27.0 g, harmonic TE 6.7±21.8 g, harmonic AL 6.4±22.9 g. The mean LVM for the AL method was closest to the cardiac MRI technique, while TE underestimated LVM. The 95% limits of agreement were consistently wide for all the 2D echocardiography modalities when compared with the cardiac MRI technique. Conclusion: The intra-observer variability in measurements of 2D echocardiographic LVM, together with the wide limits of agreement when compared to the gold standard (cardiac MRI) are sufficiently large to make serial estimates of LVM, of single patients or small groups of subjects, by 2D echocardiography, unreliable.

Regression of left ventricular hypertrophy after treatment of hypertension: Comparison of directed M-echocardiography with magnetic resonance imaging in quantification of serial mass changes

Background: This study sought to validate the reliability of serial echocardiographic measurements in detecting left ventricular (LV) hypertrophy regression by using magnetic resonance imaging (MRI) as a reference standard. Methods and Results: We studied a small population (n = 20) of patients enrolled in the Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement (PRESERVE) trial for evaluating LV hypertrophy regression. LV mass was measured by both echocardiography and MRI at baseline and after 1 year. As compared with baseline, systolic and diastolic blood pressures were significantly decreased after 1 year (all P <.05). Echocardiographic technique showed an overestimation of LV mass by 27.6 g at baseline (P =.005) and by 37.1 g after 1 year (P <.001), and there were wide 95% limits of agreement (±36.0 g at baseline; and ±27.6 g after 1 year) when compared with MRI measurement. Significant changes of LV mass from baseline of −20 ± 22 g (P<.01) and −29 ± 19 g (P <.01) were detected by using echocardiography and MRI after 1 year, respectively (P =.02), and there were similarly wide limits of agreement for change in LV mass (±24.2 g). Conclusions: Despite the use of careful methodology, echocardiographic measurement of LV mass at a single time point or for serial studies resulted in significant variation in LV mass estimates from measurement using MRI.

Why did QT dispersion die?

Considerable controversy exists about the meaning of QT dispersion (QTD). The working hypothesis of the present paper was that the necessary although not sufficient condition for the validity of QTD concept is the association of QTD with nondipolar voltage (NDPV) in T waves of the 12-lead ECG. ECGs of 4,890 subjects, 966 with coronary heart disease (CHD) and 3,844 considered CHD-free were processed using computer programs for measurement of the ratio of the first two eigenvalues (E2/E1), nondipolar voltage (NDPV), terminal T wave direction and ECG estimate of left ventricular mass (LVM). The mean NDPV in T wave was 11 muV (SD 3.9), with 6 muV (SD 1.3) in terminal 40 ms. NDPV alone explained only 6% and NDPV, E2/E1 and LVM combined 13% of QTD variance. There was a modest increase in the fraction of subjects with QTD >60 ms among subjects with NDPV in terminal T > 7 muV compared to those with NDPV >/=7 muV (15% vs. 10%). A more profound increase was associated with terminal T wave direction deviating from normal (37% vs. 12% among those with normal direction), reflecting dipolar rather than nondipolar components. The association between QTD and NDPV is weak, and QTD is unlikely to represent any meaningful myocardial repolarization event in the interval domain. It seems more logical to use direct measurement of NDPV as a potential marker of localized dispersion and heterogeneity of ventricular repolarization for evaluation of the risk of adverse cardiac events.

Accuracy of echocardiographic estimates of left ventricular mass in mice.

Genetically modified mice have created the need for accurate noninvasive left ventricular mass (LVM) measurements. Recent technical advances provide two-dimensional images adequate for LVM calculation using the area-length method, which in humans is more accurate than M-mode methods. We compared the standard M-mode and area-length methods in mice over a wide range of LV sizes and weights (62-210 mg). Ninety-one CD-1 mice (38 normal, 44 aortic banded, and 9 inherited dilated cardiomyopathy) were imaged transthoracically (15 MHz linear transducer, 120 Hz). Compared with necropsy weights, area-length measurements showed higher correlation than the M-mode method (r = 0.92 vs. 0.81), increased accuracy (bias +/- SD: 1.4 +/- 27.1% vs. 36.7 +/- 51.6%), and improved reproducibility. There was no significant difference between end-systolic and end-diastolic estimates. The truncated ellipsoid estimation produced results similar in accuracy to the area-length method. Whereas current echocardiographic technology can accurately and reproducibly estimate LVM with the two-dimensional, area-length formula in a variety of mouse models, additional technological improvements, rather than refinement of geometric models, will likely improve the accuracy of this methodology.

Estudio comparativo entre métodos ecocardiográficos y de resonancia magnética en el cálculo de la masa ventricular izquierda

Echocardiography is a widely applied technique for the estimation of left ventricular mass, although magnetic resonance is considered as a reference method for this purpose. Both techniques were compared in the present study and the usefulness of a simplified method of calculation by magnetic resonance was also tested. Left ventricular mass was determined in 42 patients by M-mode echocardiography by the application of two equations: the so-called Penn's convention and that proposed by the American Society of Echocardiography. Magnetic resonance studies were also performed, left ventricular mass being estimated from an anatomical method (summation of contiguous transverse ventricular slices) that was considered as a reference, and also by means of a geometrical method (planimetry on a single longitudinal view). Echocardiographic studies were judged as technically inadequate in 3/42 (7%) patients, while magnetic resonance was performed in all cases. Comparison between each echocardiographic method and the anatomical method of magnetic resonance showed a coefficient correlation of r = 0.70 (Penn's convention formula), and r = 0.71 (American Society of Echocardiography), with an overestimation being observed, particularly with Penn's convention method. The geometrical method of magnetic resonance showed an excellent correlation with the anatomical technique (r =0.93). Magnetic resonance is more applicable for the estimation of left ventricular mass than M-mode echocardiography, with the latter showing an overestimation when compared with magnetic resonance, particularly with the Penn's convention method. A simplified method of geometrical estimation of left ventricular mass by magnetic resonance is a reliable alternative to the anatomical method.

Biplane Long-axis Magnetic Resonance Imaging. Survey Projections for Rapid Estimation of Left Ventricular Mass and Global Function

Objective –To evaluate the accuracy and precision of biplane long-axis magnetic resonance imaging (MRI) and two-dimensional (2D)-echocardiography, for the assessment of left ventricular (LV) mass and volumes, with multislice short-axis MRI as reference standard. Design –Forty-five cardiac patients and four volunteers with varying LV dilatation and hypertrophy were examined by biplane long-axis gradient-echo MRI, 2D-echocardiography, and multiple short-axis gradient-echo MRI. Results –Compared with multislice MRI, the accuracy, i.e. the coefficient of variation (c.v.) of inter-method differences of measured variables, was median 15.7% for biplane MRI and 18.5% for 2D-echocardiography. The precision, expressed as the c.v. of repeated measurements, was median 8.5% for multislice MRI, 9.5% for biplane MRI and 12.4% for 2D-echocardiography. For the determination of LV mass index, MRI was significantly more precise (c.v.: 6.0-8.4%) than 2D-echocardiography (c.v.: 13.7-14.3%, p < 0.05). Conclusion –Biplane long-axis MRI is a fast and simplified method, offering the advantage of displaying anatomy and function in recognizable projections. For the estimation of LV mass and volumes, biplane MRI had an acceptable accuracy, and a precision that did not differ significantly from that of multislice MRI.

Association of ventricular premature complexes with electrocardiographic-estimated left ventricular mass in a population of african-american and white men and women (the atherosclerosis risk in communities [ARIC] study)

Increased left ventricular (LV) mass is often found in adults and is a powerful predictor of cardiovascular mortality. To test the hypothesis that an electrocardiographic estimate of LV mass—the Cornell voltage—is associated with ventricular premature complexes (VPCs) in free-living adults, a cross-sectional analysis of the predictors of VPCs on a 2-minute rhythm strip in a population-based sample of 13,606 middle-aged, African-American and white men and women from 4 US communities in the Atherosclerosis Risk in Communities Study baseline examinations was performed. In adults without known coronary artery disease, the prevalence of VPCs increases monotonically with increasd Cornell voltages within ethnicity and gender groups. Independent of systemic hypertension, serum electrolytes, age, heart rate, educational attainment, gender, and ethnicity, a millivolt increase in Cornell voltage was associated with a 20% to 30% increase in the prevalence odds ratio of VPCs on the 2-minute electrocardiogram. Thus, Cornell voltage is associated with VPCs on a 2-minute electrocardiogram. The association is consistent in African-Americans, whites, men, and women.

Race- and sex-specific ECG models for left ventricular mass in older populations. factors influencing overestimation of left ventricular hypertrophy prevalence by ECG criteria in African-Americans

The validity of the reported high prevalence of left ventricular hypertrophy (LVH) among African-American men and women has been questioned owing to conflicting echocardiographic evidence. We used echocardiographic left ventricular mass (LVM) from M-mode measurements to evaluate associations between LVM, body size, and electrocardiographic (ECG) variables in 3,627 white and African-American men and women 65 years of age and older who were participants of the Cardiovascular Health Study (CHS), a multicenter cohort study of risk factors for coronary heart disease and stroke. ECG amplitudes used in LVH criteria were substantially higher in African-Americans, with apparent LVH prevalence 2 to 3 times higher in African American men and women than in white men and women, although there was no significant racial difference in echocardiographic LVM. The higher apparent LVH prevalence by Sokolow-Lyon criteria in African-American men is in part owing to smaller lateral chest diameter. In women, reasons for racial differences in ECG LVH prevalence remain largely unexplained although a small part of the excess LVH in African-American women by the Sokolow-Lyon criteria appears to be owing to a larger lateral chest semidiameter in white women. ECG variables alone were too inaccurate for LVM prediction, and it was necessary to incorporate in all ECG models body weight that was properly adjusted for race and sex. This resulted in modest LVM prediction accuracy, with R-square values ranging from.22 to.36. Race- and sex-specific ECG models introduced for LVM estimation with an appropriate adjustment for body size differences are expected to facilitate evaluation of LVH status in contrasting racial population groups.

Reliability of echocardiographic assessment of left ventricular structure and function: The PRESERVE study

OBJECTIVESThe study was done to evaluate reliability of echocardiographic left ventricular (LV) mass.BACKGROUNDEchocardiographic estimation of LV mass is affected by several sources of variability.METHODSWe assessed intrapatient reliability of LV mass measurements in 183 hypertensive patients (68% men, 65 ± 9 years) enrolled in the Prospective Randomized Enalapril Study Evaluating Regression of Ventricular Enlargement (PRESERVE) trial after a screening echocardiogram (ECHO) showed LV hypertrophy. A second ECHO was repeated at randomization (45 ± 25 days later). Two-dimensional (2D)-guided M-mode or 2D linear measurements of LV cavity and wall dimensions were verified by one experienced reader.RESULTSMean LV mass was similar at first and second ECHO (243 ± 53 vs. 241 ± 54 g) and showed high reliability as estimated by intraclass correlation coefficient (RHO) = 0.93. Within-patient 5th, 10th, 90th and 95th percentiles of between-study difference in LV mass were −32 g, −28 g, +25 g and +35 g. Mean LV mass fell less from the first to the second ECHO than expected from a formula to predict regression to the mean (2 ± 19 vs. 17 ± 12 g, p < 0.001). Reliability was also high for LV internal diameter (RHO = 0.87), septal (RHO = 0.85) and posterior wall thickness (RHO = 0.83). Substantial or moderate reliability was observed for measures of LV systolic function and diastolic filling (RHO from 0.71 to 0.57).CONCLUSIONSLeft ventricular mass had high reliability and little regression to the mean; between-study LV mass change of ±35 g or ±17 g had ≥95% or ≥80% likelihood of being true change.

Discrepancies between echocardiographic measurements of left ventricular mass in a healthy adult population

Increased left ventricular (LV) mass is associated with increased cardiovascular morbidity and mortality. LV mass is commonly estimated from echocardiography according to the Penn or ASE (American Society of Echocardiography) conventions. No formal statistical test of agreement between these methods has been published. Therefore we compared M-mode echocardiographic LV mass estimates by the Penn and ASE methods in a normal adult population. M-mode echocardiographic tracings were obtained in 169 healthy volunteers and used to calculate LV mass using the Penn and ASE methods. Median values of the estimates were similar [Penn, 126 g (interquartile range 96-170 g); ASE, 129 g (105-164 g); P=0.08] and were highly intercorrelated (r=0.98, P<0.0001). However, the Bland-Altman analysis of agreement revealed significant inconsistencies between Penn and ASE LV mass values. The difference between Penn and ASE values was correlated significantly with heart size (P<0.0001), such that, for small hearts, the Penn LV mass was lower than the ASE LV mass; in contrast, for large hearts, Penn estimates were greater than ASE values. In the upper 5% of the LV mass distribution, the median value for the Penn LV mass index was 132.4 g/m(2), compared with 116.5 g/m(2) for ASE values (2P=0.017). Thus the two most common methods of echocardiographic estimation of LV mass differ significantly at the upper and lower ends of the heart size distribution. These results have important implications for both cardiac research and clinical evaluation.

Estimation of left ventricular mass by gated SPECT: Comparison with 3D echocardiography

Estimation of left ventricular mass by gated SPECT: Comparison with 3D echocardiography

Selection Bias in Clinical Research When Subjects Are Excluded Because of Failure to Estimate Left Ventricular Mass by Echocardiography

Quantitative echocardiographic imaging often is used in clinical research, but the method is not successful in all patients. The goals of this study were as follows: (1) to determine the frequency with which left ventricular mass (LVM) could be estimated by echocardiography, (2) to characterize persons in whom LVM could not be estimated from echocardiography, and (3) to determine whether failure to estimate LVM was independently related to any common cardiovascular risk factors, thereby suggesting a potential for selection bias. This research was part of a community-based case-control study of risk factors in hypertension. Five hundred hypertensive subjects and 506 normotensive age- and sex-matched control subjects were studied prospectively. The mean age was 61 years (range: 39 to 76 years), the mean weight was 74 kg (range: 37 to 127 kg), 46% of the subjects were men, and 56% had a history of smoking. Two-dimensionally guided M-mode echocardiography was attempted in all subjects for determination of LVM (Penn convention). LVM was estimated when the endocardial borders could be accurately identified from a true radial cavity diameter. LVM was estimated in 803 subjects (79.8%). Subjects in whom estimates of LVM could not be obtained were older and had the following characteristics: higher systolic blood pressure; larger chest, waist, and abdominal circumferences; higher waist/hip ratio; and larger body mass index (all P < .02). In multivariate analysis the only independent predictors of failure to estimate LVM by echocardiography were advanced age ( P = .0001), larger chest size ( P = .0001), and history of smoking ( P = .004). The inability to estimate LVM in 20% of subjects has important implications to our understanding the strength of association between potential risk factors and LVM, an independent measure of cardiovascular risk. LVM is more likely to be missing in older subjects who have a large chest and a history of smoking. The effects of such a selection bias should be considered in any analysis, and a characterization of the excluded subjects should be developed. (J Am Soc Echocardiogr 1998;11:1050-5.)

Left ventricular mass assessed by three-dimensional echocardiography using rotational acquisition.

The reproducibility of left ventricular (LV) mass measurement by two-dimensional (2-D) echocardiography is inadequate for individual assessments. This study was undertaken to evaluate the potential of LV mass determination with a new three-dimensional (3-D) echocardiographic method compared with 2-D measurements. Porcine agarose-filled left ventricles (n = 15, true mass 61-511 g) of different shapes were measured by a multiplane 3-D method based on 90 images acquired by probe rotation axis (1) perpendicular and (2) parallel to the ventricular long axis ["parasternal" (the left sternal border was not present as a reference point in this study) and apical views]. Mass was also obtained using (3) the biplane truncated ellipsoid and (4) area-length methods, as well as (5) the modified cube formula. Five hearts were not analyzed with the apical 3-D technique because of insufficient image quality. Systematic deviation from true mass was small with all methods (< 5.3%). Accuracy, expressed as 1 standard deviation of individual estimates around this systematic bias, was 7.7, 13.6, 8.2, 11.9, and 11.9% of true mass for the methods 1-5, respectively. Interobserver reproducibility, expressed as the coefficient of variation, was 4.7, 8.8, 8.1, 8.9, and 9.4% for the same methods. Limits for individual accuracy and reproducibility of LV mass estimates are nearly doubled using apical compared with "parasternal" 3-D echocardiography in vitro. A main advantage of "parasternal" 3-D compared with 2-D LV mass estimates is better reproducibility, but at the expense of greater time consumption. Apical 3-D technique is not superior to simpler 2-D methods based on "parasternal" short axis imaging.

Changes in myocardial density during postinfarction healing: effect on estimation of in vivo left ventricular mass by echocardiographic imaging

To determine whether changes in density (rho) of infarct and noninfarct zones during healing and remodeling after myocardial infarction influence estimates of left ventricular mass and detection of temporal changes by imaging, we measured weights (g) and volumes (mL) of infarct, noninfarct, and mixed tissue in hearts removed 1 to 42 days after anterior infarction in three groups of dogs: nonreperfused infarction treated with placebo or captopril, or infarcts reperfused after 2 h. In vivo mass was calculated from in vivo diastolic myocardial volumes (echocardiograms) and an assumed density of 1.05 g/mL or actual values derived from tissue weights and volumes. Over the 42 days, actual density deviated more from the assumed value of 1.05 in infarct than noninfarct zones, and the overall density was higher for reperfused than nonreperfused ventricles (1.09 vs. 1.06 g/mL, p < 0.01). Correction for density improved the correlation between absolute in vivo and postmortem mass slightly but not the detection of relative changes in mass in control, captopril, or reperfusion groups. These findings suggest that (i) densities of infarct and noninfarct zones differ and change during healing, especially after reperfusion, and (ii) correction for density provides more accurate estimates of volume-derived mass in reperfused hearts.

Changes in myocardial density during postinfarction healing: effect on estimation of in vivo left ventricular mass by echocardiographic imaging

To determine whether changes in density (rho) of infarct and noninfarct zones during healing and remodeling after myocardial infarction influence estimates of left ventricular mass and detection of temporal changes by imaging, we measured weights (g) and volumes (mL) of infarct, noninfarct, and mixed tissue in hearts removed 1 to 42 days after anterior infarction in three groups of dogs: nonreperfused infarction treated with placebo or captopril, or infarcts reperfused after 2 h. In vivo mass was calculated from in vivo diastolic myocardial volumes (echocardiograms) and an assumed density of 1.05 g/mL or actual values derived from tissue weights and volumes. Over the 42 days, actual density deviated more from the assumed value of 1.05 in infarct than noninfarct zones, and the overall density was higher for reperfused than nonreperfused ventricles (1.09 vs. 1.06 g/mL, p < 0.01). Correction for density improved the correlation between absolute in vivo and postmortem mass slightly but not the detection of relative changes in mass in control, captopril, or reperfusion groups. These findings suggest that (i) densities of infarct and noninfarct zones differ and change during healing, especially after reperfusion, and (ii) correction for density provides more accurate estimates of volume-derived mass in reperfused hearts.

Intravascular Ultrasound Catheter Evaluation of the Left Ventricle in Mice: A Feasibility Study.

With the advent of transgenic technology, it has become increasingly important to find a method for evaluating left ventricular (LV) anatomy and function in intact wild type, intervened, and transgenic mice. Mice are 1/10th the size of rats, and have body masses of 10-60 g, LV masses of 40-150 mg, LV wall thicknesses of 0.5-2 mm, and LV internal dimensions of 1-3 mm. Although the murine LV has been imaged by transthoracic (TTE) two-dimensional directed M-mode echocardiography, we explored the use of intravascular ultrasound (IVUS) catheters, with imaging from various positions, to see if better two-dimensional images of the LV could be obtained by IVUS than TTE. Eight normal mice were anesthetized using pentobarbital or avertin. The mice were studied using a commercially available IVUS system (Endosonics, Inc.). Two IVUS catheters (3.5 and 5.0 Fr) with 20-MHz multielement array transducers were used. Each catheter had a 4.0-mm imaging depth of field in all directions (360 degrees ) from the mid-point of the catheter core. Multiple imaging approaches were attempted: transesophageal (TEE); transjugular (TJ); transperitoneal (TP); and open chest, from both epicardial surface (Ep) and via direct LV puncture. TEE and TJ approaches afforded insufficient depth of field to image the entire LV in cross section. TP and Ep approaches resulted in poor images, related both to inadequate depth of field and to relatively small sector angles subtended by imaging elements. LVP (intracavitary imaging) was capable of satisfactorily imaging the LV epicardium, but was unable to image the endocardium, probably because the latter was within the 1.9-mm "ringdown" catheter artifact. All IVUS approach studies lacked sufficient temporal resolution (10 frames/sec) to reliably display systolic and diastolic frames necessary for evaluation of LV function. In contrast, as previously reported, transthoracic two-dimensionally directed M-mode echocardiograms have sufficient temporal and spatial resolution to permit accurate estimates of LV mass and systolic function. Currently, IVUS catheter-based approaches are not feasible for imaging murine LV anatomy and function. Limitations include: (1) inadequate temporal resolution might be improved by ECG gating; (2) limited depth of field possibly resolvable by lower frequency transducers; and (3) relatively large catheter size. (ECHOCARDIOGRAPHY, Volume 13, November 1996)