Angina in idiopathic hypertrophic subaortic stenosis. A clinical correlate of regional left ventricular dysfunction: a videometric and echocardiographic study.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
E L Ritman
Publications and source records attributed to E L Ritman.
Biphasic changes in maximum relaxation rate during progressive hypoxia in isometric kitten papillary muscle and isovolumic rabbit ventricle.
Explore the source record for details and available documents.
Animals↗
Direct evidence that left ventricular myocardium is incompressible throughout systole and diastole.
Incompressibility of left ventricular myocardium was tested utilizing isolated canine working left ventricular preparations. This ventricle functioned at levels comparable to the intact heart. The ventricular muscle volume was calculated with the videometric border recognition technique, which is probably the most satisfactory among the presently available techniques to measure left ventricular volume. The calculated wall mass throughout the cardiac cycle varied ranging between about +/- 5%. The difference between the calculated and weighed myocardial mass was within +/- 7% of the true weight. These findings warrant the idea that myocardial muscle mass is incompressible throughout systole and diastole; the assumption used to calculate some variables of left ventricular function.
Animals↗
Physics and technical considerations in the design of the DSR: a high temporal resolution volume scanner.
A multiple x-ray source, high-speed, transaxial scanner system (DSR) is about to undergo evaluation studies. The capability for programmable scanning modes and operator-interactive retrospective reconfiguration of scan data makes the DSR a very powerful research tool. The physics and technological basis for system design and selection of several major components of the DSR scanner are discussed.
Humans↗
[Diastolic wall thinning rate of the left ventricle].
Explore the source record for details and available documents.
Animals↗
Computed tomographic imaging of the heart: the dynamic spatial reconstructor.
A particularly important potential value of the Dynamic Spatial Reconstructor approach is that all the above data will be obtainable from a single injection of contrast agent into the right ventricle or pulmonary artery. On the basis of preliminary experimental data, a concentration of at least 80 mg of iodine per ml of contrast agent should be present in the aortic root for adequate opacification of the coronary arteries and myocardium; a bolus of at least 0.5 ml of contrast medium per kg, injected into the venous circulation, is required. As high-speed, volumetric imaging, computed tomographic scan machines such as the Dynamic Spatial Reconstructor become available with higher density resolution, perhaps a single injection of contrast agent into the right atrium or even a peripheral vein may be adequate to obtain all these measurements.
Animals↗
The DSR -- a high temporal resolution volumetric roentgenographic CT scanner.
Explore the source record for details and available documents.
Animals↗
Right and left ventricular function after the Mustard procedure in transposition of the great arteries.
Right and left ventricular function was assessed at cardiac catheterization in 33 asymptomatic patients 0.5 to 11 years (mean 4.6) after the Mustard operation for complete transposition of the great arteries. Ages at operation had ranged from 0.5 to 16 years (mean 4.2 years). Right ventricular function was assessed using videodensitometric determination of ejection fraction and ventricular volume data. Ventricular volumes were obtained by computerized video analysis utilizing Simpson's rule. The right ventricular ejection fraction was 37 +/- 11 percent (standard deviation), as assessed with videodensitometry and 42 +/- 10 percent as assessed with ventricular volume--both values less than normal (P less than 0.001). Right ventricular end-diastolic volume was significantly greater than normal (P less than 0.001) and averaged 202 +/- 70 percent, but left ventricular end-diastolic volume averaged only 125 +/- 53 percent. These observations after the Mustard operation indicate that right ventricular function is seriously decreased with relatively preserved left ventricular function. They support efforts for surgical correction utilizing the left ventricle as the systemic ventricle.
Age Factors↗
Ultra high speed transaxial image reconstruction of the heart, lungs, and circulation via numerical approximation methods and optimized processor architecture.
Explore the source record for details and available documents.
Blood Circulation↗
Application of optimized parallel processing digital computers and numerical approximation methods to the ultra high-speed three-dimensional reconstruction of the intact thorax.
In order to achieve the computational capability to carry out many thousands of cross-sectional reconstructions, necessary to support a prototype high temporal and spatial resolution cylindrical scanning multiaxial tomographic unit, a series of design, software simulation, and fabrication studies is underway to develop a special-purpose high-speed reconstruction computer. This processor will rely upon integrated circuit arithmetic components of advanced design, and highly parallel architecture to execute X-ray based transaxial reconstruction algorithms at the rate of hundreds of cross sections/sec.
Computers↗
Display and visualization of three-dimensional reconstructed anatomic morphology: experience with the thorax, heart, and coronary vasculature of dogs.
A new method, termed reprojection, is used to visualize anatomic morphology contained within three-dimensional reconstructions made up of images of multiple parallel cross sections. This method involves the projection, either orthographically into a plane or radially onto a cylinder, of the volume picture elements (voxels) of the reconstruction. Orthographic reprojection images, formed by mathematically summing the magnitudes of the voxels along selected parallel paths through the reconstructed volume, are analagous to conventional radiographs formed by the passage of an X-ray beam through the volume. The reprojection image is a two-dimensional array of picture elements that is displayed on a television monitor using a digital-to-video scan converter. Also described are the techniques of noninvasive selective tissue dissolution and numerical dissection, whereby obscuring portions of the reconstructed volume are either partially "dissolved" or totally eliminated before reprojection. Utilizing these methods, anatomic information present in a three-dimensional reconstruction but not clearly seen in a reprojection image is rendered visible after removal of superposed structures. The usefulness of these methods is demonstrated utilizing three-dimensional reconstructions of the thorax, heart, and coronary arteries of dogs.
Animals↗
High speed synchronous volume computed tomography of the heart.
A new generation, fully electronic high-speed whole-body computed tomography system is being developed to provide accurate dynamic visualization and measurement of the vital functions of the heart based on rapid changes in its shape, dimensions, and perfusion. This Dynamic Spatial Reconstruction System (DSR) will provide stop-action (1/100 sec.), rapidly sequential (60/sec.) synchronous volume (240 simultaneous, 1mm-thick cross sections) reconstructions and display of the full anatomic extent of the internal and external structures of the heart throughout successive cardiac cycles, and will permit visualization of the three-dimensional vascular anatomy and circulation throughout the myocardium.
Animals↗
Assessment of left ventricular function in secundum atrial septal defect by computer analysis of the M-mode echocardiogram.
Left ventricular function in 53 patients with secundum atrial septal defect was assessed by computer-assisted analysis of the left ventricular echocardiogram and by cardiac catheterization. The patients were divided into two groups, those younger and those older than 60 years, to investigate the effect of aging on left ventricular function. Cavity size was significantly smaller than normal (p less than 0.01) and septal motion was abnormal in 86%, but values for cardiac index, left ventricular end-diastolic pressure, velocity of circumferential fiber shortening, left ventricular filling rate, and duration of rapid filling were normal in both groups. Regional dynamics assessed in terms of peak rates of systolic thickening and diastolic thinning of the septum and posterior wall were also normal in both groups. We concluded that, although left ventricular minor dimensions are small, and septal motion is reversed in the majority of patients with atrial septal defect, left ventricular function is normal, and it does not appear to deteriorate with increased age, pulmonary hypertension, or the presence of right ventricular failure. The abnormal septal motion appears to be compensated for by enhanced septal and posterior wall percentage thickening.
Adolescent↗
Emission-computed tomography and its application to imaging of acute myocardial infarction in intact dogs using Tc-99m pyrophosphate.
The techniques of emission-computed tomography have been used to obtain in vivo quantitative estimates of the three-dimensional distribution of gamma-emitting radionuclides in dog hearts. Conjugate views, obtained for 60 equiangular projections around 360 degrees by rotating the object in front of a gamma camera, were used to reconstruct multiple-level emission transaxial images for various test objects, and for dogs with surgically induced acute myocardial infarcts. Corrections for attenuation were performed in the backprojection step of the convolution algorithm used for reconstruction. Quantitative estimates of the spatial extent and concentration of activity were obtained to within 10--15% rms error. Correlations were obtained between the radionuclide and histopathologic estimates of the extent and location of infarction.
Animals↗
Non-invasive visualization and quantitation of cardiovascular structure and function.
Explore the source record for details and available documents.
Animals↗
Spatial distribution of pulmonary blood flow in dogs in increased force environments.
Spatial distribution of pulmonary blood flow (SDPBF) during 2- to 3-min exposures to 6-8 Gy acceleration was studied, using radioactive microspheres in dogs, and compared to previously reported 1 Gy control distributions. Isotope distributions were measured by scintiscanning individual 1-cm-thick cross sections of excised, fixed lungs. Results indicate: 1) the fraction of cardiac output traversing left and right lungs did not change systematically with the duration and magnitude of acceleration; but 2) the fraction is strongly affected by the occurrence or absence of fast deep breaths, which cause an increase or decrease, respectively, in blood flow through the dependent lung; and 3) Gy acceleration caused a significant increase in relative pulmonary vascular resistance (PVR) in nondependent and dependent regions of the lung concurrent with a decrease in PVR in the midsagittal region of the thorax. Result 3 may be mediated primarily by changes in regional alveolar volume and geometry in the nondependent hemithorax conbined with hydrostatic effects of extravascular fluid and active hypoxic response in the dependent region and is superimposed on, and may override, hydrostatic effects of perfusion pressures on SDPBF during acceleration.
Adaptation, Physiological↗
Regional myocardial wall thickening response to nitroglycerin. A predictor of myocardial response to aortocoronary bypass surgery.
The peak rate of systolic wall thickening (p +/- dTw/dt) in regions of the left ventricle (LV) was determined preoperatively by biplane roentgen videometry in 18 patients before and after sublingual administration of nitroglycerin (NTG) and 3-23 months (median 12) after aortocoronary bypass surgery. The regional LV response to NTG was a reliable predictor for postoperative improvement in regional wall dynamics after successful aortocoronary bypass grafting. The ejection fraction response to NTG or surgery will not predict the regional myocardial response to NTG or surgery, nor will the regional response predict the global response. Subendocardial myocardial infarction is another cause of unimproved regional myocardial function after NTG and aortocoronary bypass surgery.
Adult↗
Cardiac function in the normal newborn: additional information by computer analysis of the M-mode echocardiogram.
Computer analysis of the M-mode echocardiogram in 50 normal newborns provided measurements of wall thicknesses and chamber size and, in addition, assessment of right and left ventricular wall, septal, and cavity dynamics throughout the cardiac cycle. Data obtained with this new technique indicated that (1) right and left ventricular cavity functions are similar in the normal newborn, (2) right and left ventricular cavity filling and emptying vary directly with peak rates of septal and ventricular wall thinning and thickening, respectively, and (3) there is a close time relationship among maximum left atrial dimension, minimum left ventricular dimension, and mitral valve opening. This analysis, which is the first complete analysis of the echocardiogram in the newborn, provides a normal range of septal and ventricular wall dynamics as well as right and left ventricular and left atrial function and has clinical implications in that it may allow early recognition of both congenital and perinatal myocardial disease.
Atrial Function↗