Comparison of transesophageal and transthoracic echocardiography for diagnosis of right-sided cardiac lesions.
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Echocardiography↗
Biomedical subjects
D D McPherson
Publications and source records attributed to D D McPherson.
Variable morphology of coronary atherosclerosis: characterization of atherosclerotic plaque and residual arterial lumen size and shape by epicardial echocardiography.
The purpose of this study was to evaluate the in vivo characteristics of coronary atherosclerosis by using high frequency epicardial echocardiography. High frequency epicardial echocardiography was used to evaluate residual lumen and wall morphology at the sites of maximal coronary atherosclerosis in 26 patients undergoing coronary artery bypass grafting. The maximal/minimal wall thickness ratio was 3.1 +/- 0.2 (mean +/- SEM) with a large range (1.3 to 7.5). Portions of the wall were normal in 16 of 31 lesions; the percent normal circumference ranged from 9% to 85%. Maximal/minimal lumen diameter ratio was 1.5 +/- 0.1 (range 1.1 to 2.9). The shape of the residual coronary lumen was noncircular in 16 lesions: oval in 13 and complex in 3. The residual coronary lumen was eccentrically placed within six arteries. These data emphasize the variability of residual lumen and wall geometry in atherosclerosis.
Coronary Artery Bypass↗
A Doppler guided retrograde catheterization system.
A Doppler guided retrograde catheterization system was developed to accurately catheterize the aortic root and left ventricular chamber without X-ray. This system consists of a 20 MHz, 0.076 mm thick x 1.016 mm diameter pulsed Doppler crystal integrated into the tip of a 100 cm multipurpose triple lumen catheter. Two lumens (0.61 mm) are used for electrodes; a third lumen (1.245 mm) may be used for guidewire and pressure determination; and the system is attached to a flow velocimeter. In an aortic arch flow model, the principles of Doppler signal guidance were confirmed with flow toward the catheter tip demonstrating positive signals and flow away from the catheter tip demonstrating negative signals. The magnitude and polarity (direction) of the detected phasic and mean velocities were utilized to guide catheterization in six dogs. Using the reversal of Doppler signal polarity to indicate branch entry and manipulating the catheter so as to maintain maximal positive axial velocity, the Doppler catheter was successfully advanced from the femoral artery to the aortic valve. Branches detected by the Doppler system were confirmed by fluoroscopy. The aortic valve was audible when approached and the left ventricular chamber was recognized by its characteristic pressure waveform. The Doppler guided retrograde catheterization system offers new technology to perform left heart catheterization without X-ray and may prove useful in a variety of settings including the development of invasive ultrasonic diagnostic and therapeutic technology.
Animals↗
Segmentation of high-frequency ultrasound images of atherosclerotic coronary arteries.
High-frequency epicardial echocardiography (HFE) is an ultrasound imaging technique capable of visualizing coronary arteries in cross-section. Use of this imaging technique in the intra-operative setting can provide information about the structure of coronary arteries. As a result of time constraints imposed in this setting, there is a need for rapid, on-line analysis of HFE images. An algorithm for segmenting HFE images of coronary arteries into wall and luminal regions is described in this paper. The algorithm is more objective and time efficient than manual methods. A validation study with post-mortem human hearts demonstrated an excellent correlation (r = 0.99 for luminal areas, r = 0.99 for wall areas) between HFE images segmented with the algorithm and by manual methods, and a good correlation (r = 0.90 for luminal areas, r = 0.86 for wall areas) between HFE images segmented with the algorithm and manually segmented images of histological samples of the corresponding coronary arterial segments. Use of the algorithm for intra-operative HFE image segmentation may reduce the amount of time required for HFE image analysis and allow for an increased amount of data collection and analysis in the operating room.
Algorithms↗
Coronary arterial remodeling studied by high-frequency epicardial echocardiography: an early compensatory mechanism in patients with obstructive coronary atherosclerosis.
Coronary arterial remodeling is a compensatory mechanism that may limit the adverse effects of coronary obstructive lesions by expansion of the entire vascular segment. To determine if this compensatory anatomic change occurs in patients, high-frequency epicardial echocardiography using a 12 MHz transducer was performed during open heart surgery in 33 patients (10 with normal coronary arteries undergoing valvular surgery and 23 with coronary atherosclerosis). From stop-frame videotape high-frequency epicardial echocardiographic images, cross-sectional measurements of luminal area and total arterial area (lumen, intima, media and dense adventitia) were made in the patients with atherosclerosis at the site of arterial lesions and from the most proximal portion of the same artery. Remodeling was defined as enlargement of the total arterial area. In normal arteries measurements were made from proximal and midarterial locations. In the patients with normal coronary arteries, total arterial area, as determined by high-frequency echocardiography, decreased from the proximal site to the midportion of the artery (from 10.4 +/- 0.9 to 8.4 +/- 1.0 mm2, p less than 0.05); luminal area also decreased (from 6.0 +/- 0.6 to 4.5 +/- 0.7 mm2, p less than 0.05). In patients with coronary arterial lesions, luminal area also decreased from the proximal site to the arterial lesion site (from 5.3 +/- 0.6 to 2.3 +/- 0.3 mm2, p less than 0.05), but total arterial area increased (from 11.6 +/- 1.0 to 13.0 +/- 1.0 mm2, p less than 0.05). Of the 25 coronary arteries evaluated, only 4 had angiographic evidence of coronary collateral formation. These data indicate that coronary arterial remodeling is an important compensatory mechanism in obstructive coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)
Cardiac Surgical Procedures↗
Quantitative shape descriptors of left-ventricular cine-CT images.
In order to assess regional diastolic function of the left ventricle (LV), we use LV cine-CT images to build finite element models. To quantitatively evaluate the accuracy of our geometric reconstruction technique used in building these models, we introduce a new measure of shape-similarity, and compare and contrast the results obtained from the new measure to the results obtained from traditional shape-similarity measures. All of these measures are used to compare the endocardial and epicardial LV contours obtained from cine-CT images of canine hearts with those obtained from video images of the same hearts. Our results show that our imaging procedure accurately reproduces shape, and further suggest that the new descriptor has the sensitivity and resolution required to distinguish between images separated by as little as 3 mm.
Animals↗
Functional chiral asymmetry in the descending thoracic aorta.
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Animals↗
A possible mechanism for neurologic ischemic events in patients with atrial septal aneurysm.
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Brain Ischemia↗
Transesophageal echocardiography in the awake elderly patient: its role in the clinical decision-making process.
To assess the impact on the management and safety of transesophageal echocardiography (TEE) in the elderly population, the results and limitations of this technique were retrospectively analyzed in 88 patients. TEE was indicated whenever the transthoracic approach was not diagnostic or was inconsistent with the clinical setting. The most frequent clinical indications were to investigate the source of emboli, assess valvular regurgitation, and identify valvular vegetations. In 72 patients (82%) TEE significantly influenced management decisions. In selected patients TEE avoided the use of more invasive diagnostic procedures. Adverse effects included occasional premature atrial or ventricular beats (11 patients), sinus bradycardia (six patients), and protracted nausea (one patient). We conclude that in elderly patients with cardiovascular diseases, TEE plays a significant role in the decision-making process without adding a significant risk.
Aged↗
What have we learned about coronary artery disease from high-frequency epicardial echocardiography?
We have used a high frequency epicardial echocardiographic technique to visualize and measure coronary artery lumens and walls in patients undergoing cardiac surgery. A 12 MHz probe (Surgiscan, Biosound Corp.) is sterilized and placed on the exposed epicardial coronary arteries. Transverse cross-sectional views are obtained from the arteries on the anterior surface of the heart: the right coronary artery to the cardiac margin and the left anterior descending coronary artery to the cardiac apex. Numerous echocardiographic-angiographic-pathological correlations have been obtained from this work. We have validated the echocardiographic lumen and wall measurements by comparing the echo measurements to histological material from pressure-distended coronary arterial segments (from animals and fresh human autopsy specimens). We have shown by comparison with angiography that coronary arteries which appear normal or only minimally diseased by angiograms are often diffusely and severely atherosclerotic. We have also evaluated the shape of atherosclerotic lesions and demonstrated a wide range of lumen shapes (oval, circular, complex) and location within the residual coronary lumen (eccentric vs. concentric). Highly eccentric lesions are characterized by relative preservation of portions of the arterial wall, and this may preserve vasoreactivity of the atherosclerotic vessel. We have also demonstrated remodeling of atherosclerotic lesions: enlargement of the total arterial area (wall plus lumen) as a compensatory mechanism to preserve the arterial lumen in the face of encroaching atherosclerosis. High frequency epicardial echocardiography offers an accurate, real-time, in-vivo method for the anatomic and functional evaluation of coronary atherosclerosis. This dynamic, in-vivo technique supports and extends information previously obtainable only from pathologic studies.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Flow Velocity↗
Videodensitometric analysis of human coronary stenoses: validation in vivo by intraoperative high-frequency epicardial echocardiography.
Videodensitometry is a nongeometric method of coronary angiographic analysis that can be used to provide an index of coronary luminal area. However, there are few direct studies in vivo of the relationship of videodensitometric data to independent measures of luminal area in humans. Although videodensitometry is theoretically independent of angiographic projection and luminal shape, validation of these assumptions in vivo is also limited. We therefore used intraoperative high-frequency epicardial echocardiography, a technique that can directly determine human coronary luminal area and shape in vivo, to further validate videodensitometry. A total of 36 arterial segments in the left anterior descending and right coronary arteries were studied by videodensitometry and high-frequency echocardiography. Videodensitometry was performed on angiograms in which the arterial segment of interest was not markedly foreshortened and was uniformly filled with contrast. In 22 discrete lesions (13 with circular lumens and nine with oval or complex lumens), videodensitometric and echocardiographic measures of luminal area correlated well (r = .86). In 33 coronary arterial segments, the effect of angiographic projection on videodensitometry was determined by comparison of the results of videodensitometry performed on left anterior oblique vs right anterior oblique angiograms of the segments. Here too, the correlation was good (r = .94, y = 1.04x + 0.002). The good correlation of left anterior oblique with right anterior oblique videodensitometric results held true for lesions with circular and oval or complex lumens. This study further validates the ability of videodensitometry to provide an index of coronary luminal area and confirms in vivo previous assumptions that the results of videodensitometric analysis are independent of angiographic projection and luminal shape.
Adult↗
Delineation of the extent of coronary atherosclerosis by high-frequency epicardial echocardiography.
Postmortem studies suggest that coronary angiography does not always accurately delineate the extent of coronary-artery disease. We examined this problem in living human hearts by performing high-frequency epicardial echocardiography at the time of cardiac surgery. The ratio of the diameter of the lumen of the coronary artery to the thickness of its wall was used to quantify the severity of coronary lesions. In 11 patients with no angiographic evidence of coronary disease anywhere in the coronary tree, the mean (+/- SEM) ratio was 5.9 +/- 0.3. In 21 patients with angiographic disease at the site evaluated by echocardiography, the mean ratio was lower (2.3 +/- 0.2, P less than 0.05), reflecting encroachment into the arterial lumen by atherosclerotic plaque. In 15 patients with arterial segments that were angiographically normal but with arterial stenoses elsewhere in the coronary tree, the mean ratio was 4.1 +/- 0.3, with marked overlap with the values in the patients who had angiographic disease at the site of the echocardiographic evaluation. These results demonstrate, in living human hearts, that diffuse coronary atherosclerosis is often present when coronary angiography reveals only discrete stenoses. This finding suggests that coronary angiography may underestimate the severity and extent of coronary disease.
Adult↗
Finite element analysis of myocardial diastolic function using three-dimensional echocardiographic reconstructions: application of a new method for study of acute ischemia in dogs.
The effect of acute myocardial ischemia on the myocardial elastic modulus has been a matter of controversy. To evaluate this question, diastolic elastic modulus was assessed by finite element analysis of left ventricular geometry using three-dimensional echocardiographic reconstructions and right and left ventricular pressure recordings. Elastic properties were estimated before and after coronary occlusion in 6 open-chest dogs. Elastic modulus values were derived by means of a computer program that determined the global elastic modulus that best predicted the diastolic changes in left ventricular geometry. In the finite element analysis after coronary occlusion, two analyses were performed: one utilizing the control elastic modulus for all segments of the left ventricle and one in which ischemic (dyskinetic) segments were assigned a higher elastic modulus. Results showed that the control elastic modulus was a poor predictor of diastolic left ventricular expansion after coronary occlusion. The finite element analysis in which the ischemic segments were assigned a higher elastic modulus better predicted ischemic diastolic wall motion patterns. Error values (difference between predicted and actual left ventricular segmental diastolic motion) were: control, 1.9 +/- 0.3 mm (mean +/- SD), ischemia, 2.9 +/- 0.5 mm, and 2.2 +/- 0.4 mm using the stiffer elastic modulus for ischemic segments. Error values were significantly higher (p less than 0.05) under ischemic conditions when the control elastic modulus was uniformly applied compared with control and ischemia with dyskinetic segments assigned a higher elastic modulus. From these data, it is concluded that the myocardial diastolic elastic modulus is increased by ischemia and that this approach may allow clinical assessment of intrinsic muscle stiffness.
Animals↗
The role of intraoperative high-frequency epicardial echocardiography during coronary artery revascularization.
The intraoperative evaluation of the technical adequacy of coronary artery bypass graft anastomoses has been limited by a lack of suitable tools. To evaluate the role of intraoperative high-frequency epicardial echocardiography we examined 82 coronary artery bypass graft anastomoses in 29 patients shortly before or just after weaning from cardiopulmonary bypass. Minor defects that did not compromise the lumen of the anastomoses were seen in two patients. One major technical error, a near total occlusion of an internal mammary-to-coronary artery anastomosis, was not apparent on external inspection, but was clearly identified with high-frequency epicardial echocardiography. This was revised immediately. Thus, high-frequency epicardial echocardiography permits the intraoperative evaluation of coronary artery bypass graft anastomoses so that technical errors can be quickly identified and corrected.
Coronary Artery Bypass↗
Intraoperative high-frequency epicardial echocardiography in coronary revascularization: locating deeply embedded coronary arteries.
During coronary revascularization, the precise location of major coronary arteries may be obscured by overlying fat, myocardial bridging, or epicardial scarring. High-frequency epicardial echocardiography can be used intraoperatively to quickly image and locate such arteries and eliminate the need for time-consuming epicardial exploration or potentially deleterious retrograde probing of distal coronary artery branches. This technique can be applied using commercially available equipment and the aid of a skilled technician.
Coronary Artery Bypass↗
Electrocardiographic and ventriculographic recovery patterns in Q wave myocardial infarction.
To further define the capacity for recovery after acute phase electrical and mechanical injury in patients with Q wave myocardial infarction who were treated with standard measures, 120 lead body surface potential maps and radionuclide angiograms were recorded at day 5 before discharge and month 6 after infarction in 23 patients with a first infarction (12 anterior and 11 inferior by standard 12 lead electrocardiographic criteria). In addition to assessment of spatial changes in electrocardiographic and wall motion patterns, five quantitative variables were evaluated: minimal Q zone integral, sigma Q wave integral, maximal ST integral, left ventricular ejection fraction and left ventricular wall motion abnormality score. From day 5 to month 6 after infarction, the only change in the inferior infarction group was a gain in sigma Q wave (-91 +/- 40 mu V X s X 10(2) to -68 +/- 24 mu V X s X 10(2); p less than 0.05). In contrast, all variables improved over the same time period in the anterior infarction group: Q zone minimum, -34 +/- 20 to -24 +/- 13 mu V X s (p less than 0.05); sigma Q wave, -160 +/- 122 X 10(2) to -120 +/- 90 mu V X s X 10(2) (p less than 0.05); ST maximum, 44 +/- 19 to 18 +/- 9 mu V X s (p less than 0.01); ejection fraction, 54 +/- 7 to 63 +/- 17% (p less than 0.05); and wall motion score, 6 +/- 3 to 3 +/- 3 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenergic beta-Antagonists↗
High frequency epicardial echocardiography for coronary artery evaluation: in vitro and in vivo validation of arterial lumen and wall thickness measurements.
The purpose of this study was to determine the accuracy of a new high frequency echocardiographic technique for the quantitative assessment of coronary artery luminal and wall dimensions. In 32 open chest animals, high frequency echocardiographic measurements (echo) of luminal diameter correlated well with in vitro histologic measurements (Histo) (r = 0.86; high frequency echo = 0.89 Histo + 0.79) (range 1.7 to 5.8 mm). Similar results were found in the evaluation of five human autopsy hearts studied in vitro. Coronary artery wall thickness measurements in human autopsy hearts showed a good correlation with high frequency echocardiographic measurements (r = 0.86; high frequency echo = 0.65 Histo + 0.24) (range 0.3 to 0.8 mm). In eight open chest calves, high frequency echocardiographic measurements of total vessel diameter correlated well with sonomicrometer measurements (Sono) (r = 0.94; high frequency echo = 1.03 Sono + 0.4) (range 2.1 to 5.3 mm). Inter- and intraobserver variability measurements of high frequency echocardiographic measurements demonstrated excellent reproducibility (r = 0.95, interobserver variability for wall thickness; r = 0.97, interobserver variability for luminal diameter; n = 10 postmortem human coronary arteries). In conclusion, high frequency echocardiography is an accurate and reproducible method of measuring coronary luminal and wall geometry and may be a potentially useful tool for in vivo coronary artery evaluation in patients.
Animals↗
Ultrasound study of acoustic properties of the normal canine heart: comparison of backscatter from all chambers.
Much effort has recently been directed toward ultrasound characterization of normal and abnormal left ventricular myocardium. The purpose of this study was to evaluate the normal acoustic properties of all four cardiac chambers as a first step toward tissue characterization of the atria and ventricles. The hypothesis was that integrated ultrasound backscatter would follow the pattern of collagen concentration in the cardiac chambers, being higher in the right side of the heart than in the left and in the atria compared with the ventricles. Seven normal canine hearts, perfusion-fixed in 10% formalin, were examined. Sections of the free walls of right and left ventricles and atria were studied in vitro with a 5 MHz transducer positioned at the focal distance from the epicardium. The radio frequency ultrasound signal energy from each specimen was derived, corrected for sample thickness and expressed as integrated backscatter, in decibel units less than the reflected energy from a stainless steel block. The backscatter was higher from the right ventricle than from the left ventricle (-64.5 +/- 1.25 [mean +/- SEM] [n = 7] versus -73.6 +/- 1.32; p less than 0.05), higher from the right atrium than from the right ventricle (-58.5 +/- 0.83 versus -64.5 +/- 1.25; p less than 0.05) and higher from the left atrium than from the left ventricle (-62.8 +/- 1.14 versus -73.6 +/- 1.32; p less than 0.05). These data show that backscatter is higher in the right ventricle than in the left ventricle and in the atria compared with the ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)
Acoustics↗