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Three-dimensional echocardiography. Advances for measurement of ventricular volume and mass.

There is a need for more accurate and reproducible serial measurement of left ventricular volume and mass in individual subjects by echocardiography. Conventional echocardiography has significant measurement variability because of its use of geometric assumptions and image plane positioning errors. Guided three-dimensional echocardiography eliminates geometric assumptions and reduces image plane positioning errors by using a "line of intersection" display. Use of three-dimensional guided imaging for a one-dimensional measurement of the left ventricle resulted in a threefold improvement of interobserver variability over conventional echocardiographic measurements. Computer-aided three-dimensional reconstruction of the ventricle for ventricular volume from a series of 8 to 10 short-axis images also achieved more than a threefold improvement of interobserver variability compared with two-dimensional echocardiography. Three-dimensional echocardiographic computation of ventricular volume and mass in healthy subjects was achieved with an accuracy comparable to magnetic resonance imaging and was superior to two-dimensional echocardiography. Three-dimensional echocardiography promises to be a more accurate method of estimating left ventricular volume and mass and may be suitable for serial study of individual subjects because of its improved accuracy and decreased interobserver variability compared with conventional echocardiographic methods.

Diastole↗

Quantification of cerebral ventricular volume in English bulldogs.

Quantitative measurement of cerebral ventricle volume of eight English bulldogs was performed using magnetic resonance (MR) imaging. The mean ventricular volume was 14.8 ml. with a range of 8.6 ml.-38.1 ml. The mean ventricular volume of two beagles was 2.2 ml with a range of 0.7 ml.-3.7 ml. The percent of intracranial volume occupied by ventricle was found to be significantly larger in bulldogs (14.0%; S.D. = 7.9%) than in beagles (Range = 1.0-4.8%). The relationship between the percent of intracranial volume occupied by ventricle and measurements of body weight, age, sex, and various measures of skull anatomy of the bulldog was also determined. The relationship between ventricular volume and neurologic dysfunction was examined. There was a possible trend between high percent of intracranial volume occupied by ventricle and low body weight. This study will serve as a pilot study for examining the relationship between ventricular volume and neurologic disease in bulldogs.

Animals↗

A new method for determination of postmortem left ventricular volumes: clinico-pathologic correlations.

A description is presented of a new and simple procedure for ventricular volume determination by means of pressure fixation of the heart and preparation of plastic molds of the ventricles which can be used to displace water in a graduated cylinder to determine the volume of the mold. Correlations between postmortem ventricular volume as measured by this method and antemortem stroke volume or clinical cardiac status indicate that a large left ventricular volume is often correlated with a low cardiac output and cardiogenic shock.

Autopsy↗

Influence of age on the effect of bidirectional cavopulmonary anastomosis on left ventricular volume, mass and ejection fraction.

OBJECTIVES: We sought to identify age-related differences in the ventricular response of patients after bidirectional cavopulmonary anastomosis (CPA) and to compare changes in the ventricular response among children < 3 years of age who underwent CPA with that of age-matched control subjects who had a systemic to pulmonary artery shunt alone. BACKGROUND: Pre-Fontan CPA has been advocated over a systemic to pulmonary artery shunt alone in patients with a single ventricle to facilitate ventricular volume unloading and minimize risk of the Fontan operation. METHODS: Our study evaluated 23 patients who initially received a systemic to pulmonary artery shunt as an initial procedure before subsequent Fontan palliation. In eight of these patients (group I), bidirectional CPA was performed before age 3 years, and in four (group II), it was performed after age 10 years. The remaining 11 patients (group III, age and weight control group for group I) were maintained with their initial shunt until they underwent Fontan palliation. Serial echocardiographic analysis was used retrospectively to evaluate left ventricular volume and mass and systolic pump function (ejection fraction) before and after bidirectional CPA. RESULTS: Through 10 months of follow-up, group I patients showed significant decreases in indexed end-diastolic volume both after CPA (120 ml/m1.5 body surface area vs. 78 ml/m1.5, p = 0.001) and in comparison with values in patients in group II and III, who showed no changes in end-diastolic volume (p < 0.001). Indexed ventricular mass decreased moderately after bidirectional CPA in group I (from 228 g/m1.5 body surface area to 148 g/m1.5) but remained unchanged in groups II and III. The differences in trends between groups I and III were significant (p = 0.03). Ejection fraction decreased significantly in group II versus group I patients (0.48 to 0.27 vs. 0.51 to 0.52, p < 0.05) after CPA. Oxygen saturation measurements before and after bidirectional CPA revealed a significant increase in group I (73% to 86%, p < 0.001) and a decrease in group II (82% to 73%, p < 0.01). CONCLUSIONS: Bidirectional CPA facilitates ventricular volume unloading and promotes regression of left ventricular mass in younger children (< 3 years) in preparation for a Fontan operation. In contrast, bidirectional CPA is of questionable value in older children as a staging procedure for Fontan palliation.

Aging↗

Right ventricular volume measurement by conductance catheter.

Continuous ventricular volume measurement by the conductance method assumes a homogeneous electrical field dispersed throughout and contained within the ventricle. Because of dense trabeculation and complex geometry, right ventricular (RV) volume description by this method may be seriously compromised. This study sought to determine the accuracy and limitations of RV volume measurement by conductance, with magnetic resonance (MR) imaging (MRI) used as a reference, in the porcine RV. Anesthetized pigs (n = 5, 45-55 kg) were placed in a 1.5-T magnet, and ECG-gated transverse MR images (5-mm slices) were acquired during the complete cardiac cycle. RV cavity volumes were subsequently determined by Simpson's technique. Animals were then instrumented with an RV conductance catheter and an ultrasonic pulmonary artery flow probe. Conductance catheter signals were recorded using single- and dual-field (SF and DF) excitation, and the saline-dilution technique was used to correct volumes for parallel conductance. The gain factor (alpha) was calculated as the ratio of conductance- to MRI-derived stroke volume (alpha SV). Variation of alpha during the cardiac cycle was computed by comparing RV conductance volumes with 1) MRI volumes at isochronal time points within the cardiac cycle [alpha(t)] and 2) the pulmonary flow integral during ejection. After calibration, the conductance-MRI volume relation was modeled linearly with good correlation [r = 0.96 (SF) and r = 0.94 (DF)], close to the line of identity. Individual conductance-MRI plots displayed a slight curvilinear relation that was concave toward the MRI axis. Consistent with this finding, alpha(t) varied significantly during the cardiac cycle (0.49 and 0.39 by SF for end systole and end diastole, respectively, P = 0.011). DF excitation resulted in improved volume measurement [alpha SV = 0.41 (SF) and 0.96 (DF)], with less variation in alpha(t) (1.0 and 0.92 by DF for end systole and end diastole, respectively, P = 0.66). These results indicate that, with calibration, the conductance method can measure absolute RV volume under steady-state conditions. However, the curvilinearity and alpha(t) variation would indicate the potential for nonlinearity when RV volumes are varied over a wider range.

Animals↗

Prognostic value of left ventricular volume response during dobutamine stress echocardiography.

AIMS: An abnormal left ventricular volume response during dobutamine echocardiography identified patients with severe coronary artery disease. The aim of the study was to assess the prognostic value of left ventricular volume changes during dobutamine stress echocardiography in 136 patients. METHODS AND RESULTS: Endpoints were defined as spontaneous cardiac events at follow-up. Left ventricular end-diastolic and end-systolic volume changes (abnormal response: < 10% and < 20% decrease, respectively) were compared with other clinical and stress test variables. During 18 +/- 7 months of follow-up, 31 cardiac events occurred: 12 hard events (cardiac death [n = 6], myocardial infarction [n = 6]) and 19 soft events (unstable angina [n = 16], congestive heart failure [n = 3]). End-diastolic volume response (P = 0.006), diabetes (P = 0.008), inducible wall motion abnormalities (P = 0.024), end-systolic volume response (P = 0.039) and inducible angina (P = 0.038) were related to a greater likelihood of cardiac events. The Cox regression analysis revealed end-diastolic volume response (odds ratio: 3.0; CI 1.44-6.32) and diabetes (odds ratio: 2.7; CI 1.28-5.69) to be independent predictors of spontaneous cardiac events. Diabetes (odds ratio: 4.0; CI 1.26-12.80) and < 40% baseline ejection fraction (odds ratio: 2.21; CI1.14-4.29) were independent predictors of hard events. CONCLUSION: An abnormal end-diastolic volume response during dobutamine stress echocardiography identifies patients with an unfavourable outcome; they should be considered for more accurate prognostic stratification.

Adult↗

Changes in ventricular volume, wall thickness and wall stress during progression of left ventricular dysfunction. The SOLVD Investigators.

To assess the long-term changes in cardiac function in asymptomatic patients with severe left ventricular dysfunction, left ventricular (cineangiography) and right ventricular (radionuclide angiography) function were assessed at baseline in 49 patients enrolled in the prevention arm of the Studies of Left Ventricular Dysfunction. After an average follow-up period of 12.4 months, 30 patients (11 randomized to the placebo group and 19 to the enalapril group) could be restudied to assess the progression of ventricular dysfunction. After 1 year of follow-up, the changes in heart rate, left ventricular end-diastolic and systolic pressure and right ventricular volumes were comparable in both groups. However, there were modest but opposite changes in left ventricular end-diastolic volume (+9 ml/m2 with placebo vs. -10 ml/m2 with enalapril, p < 0.05) and end-systolic volume (+5 ml/m2 with placebo vs. -13 ml/m2 with enalapril, p < 0.05). Mean systolic wall stress increased insignificantly in both groups, whereas ejection fraction increased from 29% to 31% in the placebo group and from 28% to 32% with enalapril (p = NS, placebo vs. enalapril). Even in asymptomatic patients with severe left ventricular dysfunction, there was a slow progression of left ventricular dilation. Enalapril administration appeared to slow this progression, but wall stress was not normalized by the treatment at the doses used in the study, indicating that at least one of the stimuli for further remodeling remained present.

Adult↗

[Determination of the real value of the ventricular volume using angiographic methods].

The developing of cuantitative angiographic procedures for evaluating the left ventricular efficiency have displaced most of the simple hemodynamic methods. The calculation of the left ventricular volume by usual ventriculography yields, as a rule, magnified values. The purpose of this paper is to determine the equation of the regression line means of which the real left ventricular volume can be calculated. A series of 12 normal hearts obtained from accidentaly deceased adult individuals (this necropsy material was afforded by the Forensic Medicine Department of México City). Previously measured amounts of a contrast substance were injected into the left ventricular cavity. The heart was filmed in a position equivalent to the chest RAO. The volume of the left ventricle was calculated using monoplane Sandler and Dodge cineventriculographic method. The results were submitted to statistic analysis. Confrontation of calculated and real values rendered a significative "r" (0.7374) and a non-significant "p" (0.001) the regression equation obteined was: y=36.97 + (0.39 x) in which: y=real left ventricular volume. x=calculated left ventricular volume.

Angiocardiography↗

Ventricular volume and cognitive deficit: a computed tomographic study.

A group of 35 patients with presumptive diagnosis of Alzheimer disease and 29 normal volunteer spouse controls, all over the age of 60, underwent medical and neurologic evaluation, an extensive psychometric battery, and CT scanning. CT ventricular volume was derived for each CT section by algorithm summation of the number of pixels within a user-defined cerebrospinal fluid range. Composite ventricular volume for each patient, obtained by summation of the individual section ventricular volumes, was corrected for brain size by dividing by the sum of the five largest brain section volumes. For the normal group, composite ventricular volume thus derived was 5.2% and for the impaired group 7.5%; the 44% difference was significant (p less than .009). Increasing ventricular volume was significantly associated with increasing severity of cognitive impairment (p less than .05).

Aged↗

Studies of left ventricular volume estimation from gated blood pool scan with the use of regression equations.

The authors carried out experimental and clinical studies of left ventricular volume measurement using equilibrium-gated blood pool scan. Using phantoms, we experimentally obtained a regression equation between radioisotope levels and camera counts. From this equation, we deduced a regression equation between camera counts and volumes, which was then used for calculation of left ventricular volumes using count technique. In an experiment using phantom with various volumes, we obtained a favorable result that the average absolute error between the true and measured volumes was as small as 6.8%. In 11 patients, we calculated the left ventricular volume and ejection fraction employing the regression equation and compared the calculated values with the values obtained by cinemascopy. This comparison disclosed an excellent correlation (r = 0.955 for end-diastolic volume, 0.997 for end-systolic volume and 0.853 for ejection fraction). Mean absolute error was 16.2% for end-diastolic volume and 16.0% for end-systolic volume. These results indicate that this technique is clinically applicable.

Adolescent↗

Validation of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volume: comparison with cast-validated biplane cineventriculography.

To determine the accuracy of attenuation-corrected equilibrium radionuclide angiographic determinations of right ventricular volumes, we initially studied 14 postmortem human right ventricular casts by water displacement and biplane cineventriculography. Biplane cineventriculographic right ventricular cast volumes, calculated by a modification of Simpson's rule algorithm, correlated well with right ventricular cast volumes measured by water displacement (r = .97, y = 8 + 0.88x, SEE = 6 ml). Moreover, the mean volumes obtained by both methods were no different (73 +/- 28 vs 73 +/- 25 ml). Subsequently, we studied 16 patients by both biplane cineventriculography and equilibrium radionuclide angiography. The uncorrected radionuclide right ventricular volumes were calculated by normalizing background corrected end-diastolic and end-systolic counts from hand-drawn regions of interest obtained by phase analysis for cardiac cycles processed, frame rate, and blood sample counts. Attenuation correction was performed by a simple geometric method. The attenuation-corrected radionuclide right ventricular end-diastolic volumes correlated with the cineventriculographic end-diastolic volumes (r = .91, y = 3 + 0.92x, SEE = 27 ml). Similarly, the attenuation-corrected radionuclide right ventricular end-systolic volumes correlated with the cineventriculographic end-systolic volumes (r = .93, y = - 1 + 0.91x, SEE = 16 ml). Also, the mean attenuation-corrected radionuclide end-diastolic and end-systolic volumes were no different than the average cineventriculographic end-diastolic and end-systolic volumes (160 +/- 61 and 83 +/- 44 vs 170 +/- 61 and 86 +/- 43 ml, respectively). Comparison of the uncorrected and attenuation-corrected radionuclide right ventricular volumes demonstrated narrower 95% confidence intervals for the attentuation-corrected right ventricular volume determinations over a wide range of cineventriculographic volumes. Thus we conclude that: (1) attenuation-corrected radionuclide right ventricular end-diastolic and end-systolic volumes compare closely with those obtained by a cast-validated biplane cineventriculographic method and (2) attenuation-corrected radionuclide right ventricular volumes correspond more closely to determinations of biplane cineventriculographic right ventricular volumes and are thus likely to be more accurate than uncorrected radionuclide right ventricular volumes.

Adolescent↗

Right and left ventricular volume characteristics in children with pulmonary stenosis and intact ventricular septum.

Right (RV) and left ventricular (LV) volume variables were calculated in 27 patients with pulmonary stenosis (PS) during routine cardiac catheterization. These included 21 patients with isolated PS (group I) and seven studies in six patients (group II) with PS and right-to-left atrial shunt. Right and left ventricular volumes were calculated according to Simpson's rule and the area length methods respectively. In group I, right ventricular end-diastolic volume (RVEDV) was not different from normal, RVEF (0.70 +/- 0.02) was significantly higher than normal, and right ventricular stroke index (RVSI) (4.36/L/min/M2 +/- 0.23) was normal. The RVEDV/LVEDV ratio was significantly less than normal (P=0.001). Multiple regression analysis indicated that RVEDV (% of normal) decreased with both age and severity of RV outflow obstruction (r=0.77). In group II, RVEDV and RVSI were both less than normal (P less than 0.001), while RVEF was normal. LVEDV in the group was slightly higher than normal (P=0.026) while LVEF was less than normal (P=0.027) and resulted in normal LVSI. The data suggest that RV and LV function in children with isolated PS are normal, and that knowledge of the RV volume variables is not essential for the management of these patients. In contrast, hearts of patients with PS and right-to-left interatrial shunt have evidence that suggest depressed ventricular function, and the quantitation of RV volume may be helpful in the management of these patients.

Adolescent↗

Ventricular volume regulation: a mathematical model and computer simulation.

A mathematical model of ventricular volume regulation based on fluid mechanical principles has been constructed using a systems engineering approach. The parameters used in the model are based on clinical observation, laboratory investigation, and presumptions that will be tested later. The model was constructed to be the basis of a computer simulation. Using the computer simulation, information obtained from the literature and laboratory hypotheses regarding pathophysiology, several enigmatic conditions were tested. The model predicted that over-production of cerebrospinal fluid, as in the case of choroid plexus papilloma, could by itself lead to distention of the ventricular system. In simulating pseudotumor cerebri, if cerebrospinal fluid absorption at the arachnoid villi is impaired and the brain itself is rendered incompressible by swelling, intracranial pressure rises and ventricular volume diminishes. Conversely, in normal-pressure hydrocephalus, if cerebrospinal fluid flow is restricted between the spinal and cortical subarachnoid spaces and the brain is made more compressible, the ventricular volume increases with minimal increases in intracranial pressure. This mathematical model and its associated computer simulation is useful in predicting the behavior of the volume of the cerebral ventricles to a variety of pathological phenomena.

Animals↗

[Evaluation of left ventricular volumes in patients with congenital heart disease and abnormal left ventricular geometry. Comparison of MRI and transthoracic 3-dimensional echocardiography].

PURPOSE: To assess the new method of 3-dimensional echocardiography in comparison to the "gold standard" MRI as to its ability to calculate left ventricular volumes in patients with congenital heart disease. MATERIALS AND METHODS: Eighteen patients between the ages of 3.9 to 37.3 years (mean: 12.8 +/- 9.7) with a geometrically abnormal left ventricle were examined using a 1.5T scanner with a fast gradient-echo sequence (TR = 14 ms, TE = 2.6 - 2.9 ms, FOV = 300 - 400 mm, flip angle = 20 degrees, matrix = 128 : 256, slice thickness = 5 mm, retrospective gating) in multislice-multiphase technique. Transthoracic 3D-echocardiography was performed with a 3.5 MHz transducer and a Tomtec (Munich, Germany) system for 3D reconstruction. RESULTS: Volume calculation was possible in all patients with 3D-echocardiography, but the muscle mass calculation only succeeded in 11 of 18 patients (61 %) due to inadequate visualization of the entire myocardium. Comparing MRI and 3D-echocardiography, the correlation was r = 0.97 for the end-systolic volumes, r = 0.98 for the end-diastolic volumes, r = 0.79 for the end-systolic muscle mass and r = 0.77 for the end-diastolic muscle mass. The agreement between both methods was considered good for the calculated end-diastolic volumes and sufficient for the calculated end-systolic volumes. The muscle mass calculations showed larger differences especially for the end-systolic mass. Mean intraobserver variability was 18.6 % for end-systolic and 8.3 % for end-diastolic volumes. CONCLUSION: In patients with an abnormal left ventricular configuration due to congenital heart disease, the new method of 3D-echocardiography is sufficient for volume calculations in preselected patients. The high intraobserver variability is still a limitation of transthoracic 3D-echocardiography in comparison to MRI.

Adolescent↗

Load dependence of cardiac output in biventricular pacing: left ventricular volume overload in pigs.

OBJECTIVE: Previous work from our laboratory has demonstrated that optimization of biventricular pacing is load dependent. Cardiac output was maximized with a ventricular-ventricular delay of +40 milliseconds (right ventricle-first pacing) during right ventricular pressure overload and with a ventricular-ventricular delay of -40 milliseconds (left ventricle-first pacing) during right ventricular volume overload. We hypothesized that a model of left ventricular volume overload would also have specific timing requirements during biventricular pacing for optimization of cardiac output. METHODS: After median sternotomy in 6 anesthetized pigs, complete heart block was induced by ethanol ablation. A conduit was grafted from the left ventricle to the left atrium to produce left ventricular volume overload. An ultrasonic flow probe was placed around the conduit to measure retrograde flow that averaged 50% of cardiac output. During epicardial atrial tracking DDD biventricular pacing, atrioventricular delay was varied between 60 and 270 milliseconds in 30-millisescond increments for 20-second intervals. After determination of optimum atrioventricular delay, ventricular-ventricular delay was varied in 20-millisecond increments from +80 to -80 milliseconds for 20-second intervals. RESULTS: Ventricular-ventricular delays had no significant effect on cardiac output with the graft clamped (control). With the graft unclamped, however, there was a statistically significant (P = .0001 by repeated-measures analysis of variance) trend toward higher cardiac output with right ventricle-first pacing. CONCLUSIONS: Right ventricle-first pacing in swine significantly increased cardiac output during acute left ventricular volume overload, but not during the control state. Understanding load-specific pacing requirements will facilitate the development of perioperative temporary biventricular pacing for acute heart failure.

Animals↗

Developmental change of lateral ventricular volume and ratio in Beagle-type dogs up to 7 months of age.

Eighteen healthy Beagle-type dogs were studied using magnetic resonance (MR) imaging from a few days after birth up to 7 months of age. We evaluated the onset of lateral ventricular expansion, the developmental change of lateral ventricular volume and the ratio of the largest to the smallest lateral ventricular volume. The onset of lateral ventricular expansion was defined as the day that the expansion by cerebrospinal fluid (CSF) was first visible in unilateral or bilateral lateral ventricles on the transverse images at the level of the intraventricular foramen. It was found that the expansion of lateral ventricles were first detectable at 3-4 weeks. Lateral ventricular volume ratio varied most from the onset of lateral ventricular expansion to 75 days of age and stabilized after that, although absolute brain and lateral ventricular volumes continued to increase.

Animals↗

[Determination of ventricular volumes by a non-geometric method using gamma-cineangiography].

The authors suggest a new way of determining ventricular volume by a non-geometric method using gamma-cineangiography. The results obtained by this method were compared with those obtained by a geometric methods and contrast ventriculography in 94 patients. The new non-geometric method supposes that the radioactive tracer is evenly distributed in the cardiovascular system so that blood radioactivity levels can be measured. The ventricular volume is then equal to the ratio of radioactivity in the LV zone to that of 1 ml of blood. Comparison of the radionuclide and angiographic data in the first 60 patients showed systematic values--despite a satisfactory statistical correlation (r = 0.87, y = 0.30 X + 6.3). This underestimation is due to the phenomenon of attenuation related to the depth of the heart in the thoracic cage and to autoabsorption at source, the degree of which depends on the ventricular volume. An empirical method of calculation allows correction for these factors by taking into account absorption in the tissues by relating to body surface area and autoabsorption at source by correcting for the surface of isotopic ventricular projection expressed in pixels. Using the data of this empirical method, the correction formula for radionuclide ventricular volume is obtained by a multiple linear regression: corrected radionuclide volume = K X measured radionuclide volume (Formula: see text). This formula was applied in the following 34 patients. The correlation between the uncorrected and corrected radionuclide volumes and the angiographic volumes was improved (r = 0.65 vs r = 0.94) and the values were more accurate (y = 0.18 X + 26 vs y = 0.96 X + 1.5).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

The effect of variations of ventricular volume on the electrocardiogram. A comparison of two model simulations.

Two previously published models of the electrocardiogram are compared and evaluated to determine the causes and nature of the relationship between variations in ventricular volumes and surface potential. Both models included a relatively high conductivity spherical heart in a spherical torso, but in one the source was a single dipole, while in the other the source was a double-layer spherical cap. Volume conductor effects (that is the change in electrical conductivity of the torso associated with ventricular volume changes) caused a decrease in surface potential with increase in ventricular volume. Changes in position of the heart and of the strength of the activation wavefront with increases in volume may explain the increase in surface potential with ventricular volume observed in experimental studies.

Cardiac Volume↗