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Biomedical subjects

A D Waggoner

Publications and source records attributed to A D Waggoner.

At least 37 records · Page 2Linked to original sources
PubMed1993

On-line assessment of left atrial area and function by echocardiographic automatic boundary detection.

BACKGROUND: Direct assessment of left atrial (LA) function has not been previously performed by noninvasive techniques; rather, LA function has been evaluated only indirectly via the analysis of transmitral flow velocity by Doppler. The recent development of real-time two-dimensional echocardiographic automatic boundary detection suggests that LA dimensions can be measured instantaneously to provide on-line assessment of its systolic and diastolic functions. METHODS AND RESULTS: We performed echocardiographic assessment of LA dimensions and function with automatic boundary detection in 45 patients by using the apical four-chamber view. Thirty-seven patients had structural or functional cardiac abnormalities, 35 patients were in sinus rhythm, and 10 patients had atrial fibrillation. Moderate to severe mitral regurgitation (MR) was noted in 16 patients. We also studied 10 control subjects to assess normal values of LA cavity area and indexes of function. From the instantaneously derived LA area, we derived indexes of systolic atrial expansion and diastolic atrial emptying. There were excellent correlations between the on-line-derived LA areas and those measured off line from videotaped images of conventional echocardiography (r = .91 for end-diastolic and .93 for end-systolic areas; SEE, 4.0 and 3.8 cm2, respectively). Patients in atrial fibrillation had depressed diastolic emptying index (0.17 +/- 0.05) compared with those in sinus rhythm (0.28 +/- 0.12; P < .02). Furthermore, patients with chronic MR exhibited larger LA cavity areas and depressed systolic and diastolic LA function as compared with those without MR. In addition, the Doppler-determined mitral E/A ratio was related to the ratio of early diastolic-to-late diastolic change in LA cavity area (r = .79; SEE 0.6; n = 35). CONCLUSIONS: Instantaneous LA cavity area measurement by echocardiographic automatic boundary detection is accurate and feasible in patients with diverse cardiac disorders. Patients with atrial fibrillation had a depressed diastolic emptying index and those with significant mitral regurgitation had depressed systolic expansion index as well. LA functional indexes in both systole and diastole can be derived providing an approach for quantitative evaluations of left atrial-left ventricular interactions based on geometric assessment noninvasively.

Atrial Fibrillation↗
PubMed1992

Automated, on-line quantification of left ventricular dimensions and function by echocardiography with backscatter imaging and lateral gain compensation.

To provide on-line quantification of left ventricular cavity dimensions and function by echocardiography 60 control subjects and 10 patients with cardiac dysfunction were studied. A novel, ultrasound imaging system was used which was developed to detect and track, in real time, ventricular endocardial blood boundaries based on quantitative assessment of acoustic properties of tissue. In addition, lateral gain compensation, a robust and novel image enhancement procedure, was used to provide instantaneous measurement and display of cavity areas and functional indexes on a beat-by-beat basis within regions of interest drawn around the blood pool cavity. In control subjects, short-axis end-diastolic area averaged 13.1 +/- 3.7 cm2 (SD), end-systolic area 5.9 +/- 2.7 cm2, and fractional area change 55.6 +/- 11.2%. Apical views yielded corresponding values of 23.8 +/- 4.5 cm2, 15.5 +/- 3.4 cm2 and 34.7 +/- 7.8%. Instantaneous peak rate of cavity area change approximated 50 cm2/s in systole and 60 cm2/s in diastole in each view. Serial measurements of area and functional index were reproducible over intervals of 2 to 3 weeks. Patients with dilated ventricles exhibited average apical view area values of 49.1 +/- 6.1 cm2 and 43.1 +/- 4.9 cm2 in diastole and systole with a fractional area change of 12.2 +/- 3.0%. Thus, results with on-line echocardiographic backscatter imaging-assisted automated edge detection are reproducible and capable of delineating cardiac dysfunction conveniently, promptly and serially at the bedside.

Adult↗
PubMed1992

Frequency and significance of intrapulmonary right-to-left shunting in end-stage hepatic disease.

Intrapulmonary vascular abnormalities consisting of arteriovenous malformations and capillary dilatations have been described in patients with severe liver disease. These intrapulmonary vascular abnormalities can result in intrapulmonary right-to-left shunting and hypoxemia. Twenty-five of 53 patients (47%) with end-stage hepatic disease were found to have contrast echocardiographic evidence of intrapulmonary right-to-left shunting. There was no difference in mean age, gender distribution, or severity of hepatic disease in those with and without evidence of such shunting. Although there was no difference in mean partial arterial oxygen pressure (PaO2) values in the 2 groups (82 +/- 11 vs 76 +/- 11 mm Hg), the mean PaO2 value of those with at least 2+ left ventricular opacification (2 to 4+) was significantly lower (66 +/- 3 mm Hg, n = 8; p less than 0.01). Unexpectedly, patients with evidence of intrapulmonary shunting had a lower mortality rate before transplantation (3 of 25, 12%) than those without evidence of shunting (10 of 28, 36%) resulting in a significant difference in actuarial survival (p less than 0.05) by the end of the follow-up period. It is concluded that intrapulmonary right-to-left shunting occurs frequently in patients with end-stage liver disease and may be a marker of a positive biologic process that, in some way, leads to improved short-term survival.

Adult↗
PubMed1992

Quantitative ultrasonic imaging: tissue characterization and instantaneous quantification of cardiac function.

Quantitative myocardial tissue characterization is being developed to complement and expand conventional echocardiography by delineating the physical state of myocardium under diverse pathophysiologic conditions. Real-time quantitative integrated backscatter imaging has already been applied to patients with ischemic heart disease, hypertrophic cardiomyopathy, and cardiac allograft rejection in clinical investigations performed in the United States, Europe, and Japan. A recently introduced modification of imaging processing algorithms employed for characterization of tissue facilitates automatic detection of endocardial-blood interfaces and on-line quantification of ventricular size and function. Further progress and anticipated developments in quantitative ultrasonic imaging will undoubtedly augment the clinical applications of tissue characterizations based on myocardial integrated backscatter for improved diagnosis, elucidation of pathophysiology, and assessment of cardiac function.

Animals↗
PubMed1992

Differentiation of normal and ischemic right ventricular myocardium with quantitative two-dimensional integrated backscatter imaging.

We have previously shown that ultrasonic tissue characterization with two-dimensional (2D) guided M-Mode acquisition of integrated backscatter (IB) identifies ischemic and infarcted myocardium. However, there is no information regarding the applicability of IB in assessment of right ventricular (RV) myocardial acoustic properties. Thus, we performed IB imaging of the RV in a group of 45 consecutive patients and were successful in 16, all of whom had normal RV wall motion. This group was compared to 8 additional patients studied acutely with clinical criteria of RV infarction. Real-time IB from RV was obtained from parasternal long axis or subcostal views. Diastolic-to-systolic cyclic variation of IB in normals was 4.8 +/- 0.9 dB (+/- SD). No significant difference was observed between parasternal and subcostal views (5.2 +/- 0.8 and 4.5 +/- 0.9 dB). Mean value of delay (R wave to nadir of backscatter normalized to the electrocardiographic Q-T interval) was 0.85 +/- 0.07. Patients with RV infarction had significantly lower values averaging 3.2 +/- 0.8 dB (p less than 0.001 vs. normals); cyclic variation of IB was present in all despite severe hypokinesis in 4/8. Mean value of normalized delay was 0.80 +/- 0.04 and was not different from normals. Thus, tissue characterization provides quantitative information regarding RV myocardial structure and function. Preservation of IB cyclic variation in patients with RV infarction suggests residual RV myocardial viability.

Coronary Disease↗
PubMed1992

Abnormal myocardial acoustic properties in diabetic patients and their correlation with the severity of disease.

Although patients with diabetes mellitus may be afflicted by cardiomyopathy, its prevalence and nature are controversial. Studies have shown that fibrosis alters the acoustic properties of the heart in animals and humans and that the changes are detectable by cardiac tissue characterization with ultrasound. The present study was performed to characterize myocardial acoustic properties in patients with insulin-dependent diabetes to determine whether ultrasound tissue characterization could detect changes potentially indicative of occult cardiomyopathy. The magnitude of cyclic variation of myocardial ultrasound integrated backscatter and its phase delay with respect to the onset of the cardiac cycle in the septum and posterior wall of the left ventricle were measured in 54 patients with diabetes who had no overt cardiac disease. Conventional echocardiography documented normal ventricular systolic function in 96%. As compared with results in age-matched patients without diabetes studied previously, cyclic variation of integrated backscatter was reduced (4.6 +/- 0.8 vs. 3.6 +/- 1.4 dB; p less than 0.001). In addition, delay was significantly increased (0.86 +/- 0.09 vs. 0.99 +/- 0.15). The primary analysis of the data focused on differences among the diabetic patients. Reduction of cyclic variation of backscatter was greatest in patients with diabetes who had neuropathy (3.2 +/- 1.0 dB; p less than 0.001) as was the increase in delay (1.04 +/- 0.16, p less than 0.001 vs. values in patients without neuropathy). Retinopathy and nephropathy were associated with abnormal myocardial acoustic properties as well. Thus, abnormalities that may reflect fibrosis or other occult cardiomyopathic changes in diabetic patients without overt heart disease are readily detectable by myocardial tissue characterization with ultrasound and parallel the severity of noncardiac diabetic complications.

Cardiomyopathies↗
PubMed1992

On-line assessment of ventricular function by automatic boundary detection and ultrasonic backscatter imaging.

To provide an approach suitable for on-line analysis of ventricular function, a conventional two-dimensional ultrasound imaging system was modified to detect and track blood-tissue interfaces in real time based on their quantitative acoustic properties. This modification permitted on-line display of the left ventricular cavity area, fractional area change, volumes and ejection fraction on a beat by beat basis. Images were obtained from 54 patients and 12 normal subjects with broad ranges of ventricular dimensions and systolic function. On-line measurements of cavity areas were compared with off-line measurements of cavity areas (analysis of videotaped conventional images). Left ventricular cavity areas measured on-line from short-axis views correlated closely with off-line views as did areas from apical views. On-line fractional area change correlated well with ejection fraction calculated off-line. More than 70% of patients could be studied adequately with the approach developed. Thus, automatic boundary detection based on quantitative assessment of tissue acoustic properties permits on-line quantitation of ventricular cavity areas and indexes of function.

Algorithms↗
PubMed1992

On-line quantification of ventricular function during dobutamine stress echocardiography.

To develop an approach for on-line quantification of left ventricular size and function during pharmacological stress testing we employed echocardiographic automatic edge detection via integrated backscatter imaging during dobutamine infusion in 27 patients. Ventricular cavity areas, fractional area change and rate of cavity area change were obtained on-line with instantaneous graphic display of the data. When compared to baseline image data, patients with a normal response exhibited modest (15%) reduction in end-diastolic cavity areas at peak dobutamine level, but marked (33%) reduction in systolic areas yielding a 52% increase in fractional area change (n = 13; P < 0.001). The second group of patients (n = 14) had an abnormal response characterized by limited changes in measured parameters of ventricular function and reduced fractional area change (P < 0.05). On-line quantification during pharmacological stress echocardiography is a promising addition to the test for surveillance and objective instantaneous evaluation of global cardiac responses.

Adult↗
PubMed1991

Two-dimensional contrast echocardiography in the detection and follow-up of congenital pulmonary arteriovenous malformations.

Pulmonary arteriovenous (A-V) malformation is frequently a manifestation of Osler-Weber-Rendu syndrome (hereditary hemorrhagic telangiectasia). We identified 14 patients (9 men and 5 women) with A-V malformation by contrast echocardiography; 10 patients with atrial right-to-left shunt served as control subjects. Agitated saline solution (10 ml) was injected through a peripheral vein during echocardiographic imaging. The delay in the appearance of microcavitations in the left atrium was measured (in number of frames) after right atrial appearance. The degree of left ventricular opacification was graded 1 to 4+ (where 4+ = intense left ventricular endocardial outline, and 1+ = minimal opacification). Results indicated patients with A-V malformation had a significant delay (p less than 0.001) in left atrial appearance of microcavitations compared with those with atrial right-to-left shunt (66 +/- 27 vs 21 +/- 7 frames, mean +/- 1 standard deviation). In the group with A-V malformation, abnormal blood gases were present in only 6 of 14 patients and chest x-ray was positive in 7. Pulmonary angiography was performed in 11 of 14 patients with positive contrast echocardiography, and all 11 had A-V malformation identified. In patients with 3 to 4+ left ventricular opacification (n = 8), large (greater than 5 mm feeding vessel) or multiple malformations were present, whereas patients with small or isolated malformation had 1 to 2+ left ventricular opacification. Balloon occlusion of malformations was performed in all 11 of these patients; repeat contrast echocardiography revealed significant diminution of right-to-left shunt in 9, and 2 required repeat embolotherapy for an additional previously undetected A-V malformation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Left ventricular outflow obstruction resulting from insertion of mitral prostheses leaving the native leaflets intact: adverse clinical outcome in seven patients.

Left ventricular (LV) outflow obstruction may result from retaining the anterior mitral leaflet when a mitral prosthesis is inserted in the mitral anulus. We retrospectively reviewed the echocardiograms (two-dimensional Doppler and Doppler color flow imaging, or transesophageal with color flow imaging) obtained in seven patients with preoperative mitral regurgitation who had a prosthesis implanted with the native mitral leaflets left intact. Systolic anterior motion of the native anterior mitral leaflet, as seen in dynamic LV outflow tract obstruction, was observed in six of seven patients. LV fractional shortening preoperatively was less than or equal to 0.25 in all (mean 0.20 +/- 0.04) and did not significantly (p = ns) increase postoperatively (mean 0.27 +/- 0.12). Color flow imaging revealed disturbed systolic flow in the LV outflow tract in five patients, and all had systolic anterior motion of the native anterior mitral leaflet. Continuous wave Doppler detected significant systolic LV outflow tract jets in five patients averaging 4.1 +/- 0.9 m/sec. Mitral prosthetic function was normal (pressure half-time of 81 +/- 25 msec and mean gradient of 7 +/- 3 mm Hg +/- SD) in five patients. Clinical follow-up revealed that all had died, six of them within 2 months of their operation. Thus systolic anterior motion of the native anterior mitral leaflet occurs commonly after prosthetic mitral valve insertion with the native leaflets left intact. Continuous wave Doppler often demonstrates increased systolic LV outflow tract velocities consistent with dynamic LV outflow obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Saline contrast enhancement of tricuspid regurgitant jets detected by Doppler color flow imaging.

Contrast techniques have been used to improve detection of peak velocities by Doppler spectral analysis. To define the effect of contrast enhancement on the tricuspid regurgitation (TR) jet area and length, 29 patients were studied (25 transthoracic, 4 transesophageal) with 2-dimensional color flow imaging. Three- to 5-ml of agitated saline was injected and images were obtained from 4-chamber views at 12- or 16-cm depth setting. Color gain was optimized to display TR jet at baseline and then reduced to minimal settings before injection. Measurements of TR jet area and length were made in 3 to 5 consecutive cycles. A ratio of TR jet area to 2-dimensional area was derived. TR jet area at baseline was 4.7 +/- 3.6 cm2 and increased significantly (p less than 0.0001) in 26 patients to 8.1 +/- 6.3 cm2 after contrast enhancement. Jet length at baseline was 3.4 +/- 1.7 cm and increased significantly (p less than 0.0001) in 20 patients to 4.1 +/- 1.8 cm after contrast enhancement. The ratio of TR jet area to right atrial area also increased significantly (p less than 0.0001) to greater than 0.20 in 18 of 28 patients after enhancement. Increases in jet area and length were not associated with changes in TR jet or diastolic inflow velocities measured by continuous wave Doppler at baseline and after contrast. Thus, contrast enhancement increases the amplitude of Doppler signals responsible for transvalvular and regurgitant flow. By reducing the effect of attenuation and improving signal-to-noise ratio, it improves delineation of the TR jet using color flow imaging.

Adult↗
PubMed1990

Principles and physics of Doppler.

This article reviews the available Doppler instrumentation and application to assessment of blood flow velocity. A review of the basis of quantitative measurements such as volume flow, modified Bernoulli and continuity equations, and pressure half-time are discussed. A brief technical description of Doppler color-flow mapping is presented with reference to data acquisition and display.

Blood Flow Velocity↗
PubMed1985

Fatal aortic rupture presenting as chest pain in an adolescent. The role of echocardiography in occult cystic medial necrosis.

An adolescent female with occult cystic medial necrosis died following spontaneous aortic rupture. A large saccular aortic aneurysm that had ruptured into the pericardial space was demonstrated by two-dimensional echocardiography and confirmed at surgery. Echocardiographic screening of the patient's family members revealed a 13-year-old brother with unsuspected aortic root dilatation. He is now being followed for possible progression of his disease. This case demonstrates the role of echocardiography in cystic medial necrosis. It can aid the acute management of patients with aortic dissection or aneurysm. It can also define patients with occult disease who require serial follow-up and genetic counseling.

Adolescent↗
PubMed1985

Echocardiographic evaluation of left ventricular function, mass and wall stress in children with isolated ventricular septal defect.

M-Mode echocardiography was performed in 22 normal children and 22 children with ventricular septal defects. Left ventricular and left atrial chamber dimensions and wall thicknesses were measured in all patients. Utilizing these data, indices of left ventricular function were derived: shortening fraction, velocity of fiber shortening, peak diastolic fiber lengthening, end-systolic wall stress, radius thickness ratio, and ventricular mass. The results showed that ventricular septal defect was associated with enlarged left ventricular and atrial dimensions and increased shortening fraction, but that velocity of shortening and early diastolic lengthening remained normal. Left ventricular mass was increased, thus maintaining normal wall stress and radius/thickness ratio. Cardiac failure complicating ventricular septal defect was associated with enlarged left ventricular and atrial dimensions (indexed for weight). Ventricular mass, wall stress and function, however, were similar in subjects with ventricular septal defect, with or without cardiac failure. Since left ventricular mass was adequate to maintain wall stress and function in subjects with heart failure, other factors were presumably responsible for heart failure complicating ventricular septal defect.

Journal Article↗
PubMed1984

Comparison of two-dimensional echocardiography with gated radionuclide ventriculography in the evaluation of global and regional left ventricular function in acute myocardial infarction.

Two-dimensional echocardiography and gated radionuclide ventriculography were performed in 93 patients (66 men, 27 women; mean age 61 years) with 95 episodes of acute myocardial infarction within 48 hours and at 10 days after infarction. Electrocardiographic sites of infarction were: 35 anterior, 49 inferoposterior and 11 nonlocalized. Abnormal motion of the anterior wall, septum or apex was seen in 97 and 100% of anterior infarctions by radionuclide ventriculography and echocardiography, respectively. Abnormal motion of an inferior or posterior wall segment was seen in 91% of inferoposterior infarctions by echocardiography versus 61% seen by radionuclide ventriculography. Ejection fractions determined by echocardiography and radionuclide ventriculography correlated well (r = 0.82) and did not change from the first 48 hours to 10 days after infarction (0.48 +/- 0.14). Similarly, wall motion score showed minimal change from the first 48 hours to 10 days. In-hospital mortality was 37 and 42% in patients with an ejection fraction of 0.35 or less by echocardiography and radionuclide ventriculography, respectively. No mortality was seen in patients with an ejection fraction above 0.40 by either test. The echocardiographic wall motion score was also predictive of mortality (40 versus 2%; score less than or equal to 0.50 versus greater than 0.50). The 1 year mortality rate in the 81 short-term survivors was 17%. Mortality was lowest in patients with an ejection fraction above 0.49 or wall motion score above (0.79 (2 to 5%) and worse in those with an ejection fraction below 0.36 or wall motion score below 0.51 (36 to 63%) by either technique. Thus in acute myocardial infarction, echocardiography and radionuclide ventriculography provide a comparable assessment of left ventricular function and wall motion in anterior infarction. Echocardiography appears more sensitive in detecting inferoposterior wall motion abnormalities. Both techniques are capable of identifying subgroups of patients with a high risk of death during the acute event and with an equally high mortality rate over a 1 year follow-up period.

Adult↗
PubMed1983

Detection of coronary artery disease with exercise two-dimensional echocardiography. Description of a clinically applicable method and comparison with radionuclide ventriculography.

Two-dimensional echocardiography (2-D echo) was performed in 73 patients evaluated for coronary artery disease (CAD) and in four normal volunteers before and immediately after a maximal treadmill exercise test. Diagnostic images were obtained from the apical and parasternal windows. In 17 patients with normal coronary arteriograms, ejection fraction (EF) increased from 66 +/- 9% (+/- SD) at rest to 73 +/- 8% after exercise (p less than 0.001), while in 56 patients with proved CAD, EF fell from 56 +/- 13% at rest to 53 +/- 16% after exercise (p less than 0.01). The sensitivity of postexercise 2-D echo for detecting CAD (based on abnormal EF response and/or regional dyssynergy) was 91% (51 of 56 patients) and the specificity was 88% (15 of 17). Sensitivity for one-, two- and three-vessel disease was 64% (seven of 11), 95% (20 of 21) and 100%, respectively. Patients with multivessel disease showed a significant fall in a wall motion score index, from 0.79 +/- 0.25 to 0.63 +/- 0.26. Exercise radionuclide ventriculography (RNV) was also performed in 41 of the subjects (17 normals and 24 CAD patients) on a bicycle ergometer. The overall sensitivity of 2-D echo in this subgroup was 92%, compared with 71% for RNV. The sensitivity of 2-D echo for one-vessel disease (n = 4) was 50%, that for two-vessel disease (n = 12) was 100% and that for three-vessel disease (n = 12) was 100%. Respective values for RNV were 0%, 80% and 90%. The specificity of 2-D echo was 88% and that of RNV was 82%. A significantly higher peak heart rate response was observed on the treadmill than on the bicycle ergometer in both CAD patients and normal subjects. We conclude that postexercise 2-D echo is a clinically applicable technique for the diagnosis and evaluation of CAD patients and compares favorably with exercise RNV.

Adult↗