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Biomedical subjects

R L Popp

Publications and source records attributed to R L Popp.

At least 145 records · Page 8Linked to original sources
PubMed1981

In vitro quantitation of canine left ventricular volume by phased-array sector scan.

Ultrasonic sector-scan images can delineate the entire circumference of the canine left ventricle in vitro. This study was undertaken to (1) assess the accuracy of sector scanning for estimating canine left ventricular volume in vitro compared to volume estimates by M-mode echo in the same hearts and (2) determine the optimal techniques for estimating left ventricular volume with sector scanning. 16 volumes (1 volume from 8 hearts and 2 volumes from 4 hearts) were estimated by obtaining sector-scan images from orthogonal long-axis, short-axis and apical views. The sector-scan volumes were calculated by single and biplane area-length methods, as well as biplane Simpson's rule methods, and compared to measured left ventricular volumes. M-mode echo volumes were calculated by cubing the mid-ventricular minor-axis diameter. Sector-scan views containing a long-axis dimension plus the short-axis dimension of the left ventricle had a high correlation with true left ventricular volume while sector-scan views not containing a long-axis view showed only a fair correlation with volume. M-mode echo produced a poor estimate of the true left ventricular volume. It is concluded that (1) sector scanning can provide highly accurate in vitro volume estimates of canine left ventricles which is superior to estimates derived by M-mode echocardiographic methods and (2) the optimal sector-scan views for estimating left ventricular volume are those that make the fewest assumptions about left ventricular geometry and have the greatest amount of dimensional information.

Animals↗
PubMed1981

The relationship of pulmonary valve motion to the motion of surrounding cardiac structures: a two-dimensional and dual M-mode echocardiographic study.

To assess the relationship of late diastolic pulmonary valve motion to motion of adjacent cardiac structures, we performed two-dimensional and dual M-mode echocardiography on 15 pulmonary normotensive (group A) and nine pulmonary hypertensive subjects (group B). Simultaneous pulmonary valve and posterior aortic wall a-waves were less prominent in group B than in group A (p less than 0.001), and their amplitudes were linearly related within each group (r = 0.83). Analysis of two-dimensional studies confirmed a relationship between pulmonary valve and posterior aortic wall late diastolic motion. No subject had independent presystolic motion of the pulmonary valve within the pulmonary artery. Subjects with shallow a-waves had impaired left atrial emptying compared with those with normal a-wave amplitudes (p less than 0.01). We conclude that the pulmonary valve a-wave does not represent independent valvular displacement, but rather, reflects motion of the entire cardiac base. Variations in a-wave morphology may result, at least in part, from the effects of altered ventricular geometry and compliance on left atrial emptying.

Aorta↗
PubMed1981

The use of echocardiography in diagnosing culture-negative endocarditis.

We reviewed M-mode and two-dimensional echocardiographic findings in 11 patients with abacteremic endocarditis to study the application of echocardiography in this setting. All patients had negative blood cultures but underwent surgery that confirmed the presence of active infective endocarditis. The infection involved native valves in five patients and prosthetic valves in six patients. Valvular masses were identified in eight patients. The other three patients, who had prosthetic aortic valves, had diastolic mitral valve vibration characteristic of aortic regurgitation. One of these also showed dehiscence of the prosthesis. Three patients had poorly defined clinical illnesses and echocardiography was a prime element in the diagnosis because valvular masses were identified. The operation was facilitated by knowledge of the mass indicated by echocardiography in these eight cases. Also, the surgical approach was affected by knowledge of dehiscence and perivalvular abscess formation in two cases each.

Abscess↗
PubMed1981

Spontaneous dissection of the ascending aorta diagnosed by two-dimensional echocardiography.

In two patients with acute dissection of the ascending aorta, the diagnosis was made with two-dimensional echocardiography and confirmed by aortography. The echocardiograms localized the intimal flap and false channel in both cases. Although clinical evaluation and indicated radiologic studies remain the primary modalities of diagnosis in acute aortic dissection, two-dimensional echocardiography may be a useful additional diagnostic technique.

Adult↗
PubMed1980

Ultrasonic diagnostic instruments.

The underlying physical principles and current limitations of diagnostic ultrasonic instruments are reviewed. Recently developed ultrasonic imaging devices using pulsed-reflected ultrasound are discussed in detail. These instruments transmit short trains of 1.5- to 10-megahertz sound. Echoes reflected from tissue are converted to electrical signals, which are presented on a display device to outline the contour of tissues and organs within the body. The physical resolution of the system is dependent on several design factors in addition to the transmitted sound frequencies. A resolution volume of approximately 1.5 by 3 by 4 millimeters is achieved optimally with commercially available systems operating at 2.25 megahertz. The various instrument designs are described in the context of clinical usage. Because the sound is diffracted, refracted, and reflected, tghe imaging considerations are different from those of x-ray imaging. Diagnostic devices based on the Doppler principle are distinguished from pulsed-reflected ultrasonic instruments.

Auscultation↗
PubMed1980

The source of ultrasound contrast effect.

Evidence that microbubbles are the main sources of ultrasound contrast in injected solutions has been largely indirect. To investigate this directly, we examined freshly agitated indocyanine green, freshly agitated water, commercially prepared precision microbubbles (diameter 75 +/- 25 mu) in gelatin, carbonated water, "degassed" indocyanine green solution, and "degassed" water in one or more of four different assay systems. Only fluids with microbubbles produced ultrasound contrast. Injected contrast material rose in a water bath at a rate that identified it as being caused by microbubbles. Indocyanine green and gelatin surface tensions were measured and found to be low (43 dynes/cm2), thus explaining their tendency to stabilize the microbubbles that cause ultrasound contrast effect when injected and to hold foam after agitation. The force of hand injections (force similar to that used clinically through catheters and 19-gauge or 23-gauge needles) was below the force needed to cause cavitation or ultrasound contrast effect. Microbubble content could be quantified by the decrease in amplitude of the echo from a structure distant to the microbubbles. We conclude that that the ultrasound contrast effect seen in peripherally injected fluids is caused by microbubbles present in the injectant. The contrast is not due to cavitation at needle tips, and it can be quantified over a limited range. Improved design for a peripheral contrast agent is suggest.

Animals↗
PubMed1980

Intrapericardial abnormalities in patients with pericardial effusion. Findings by two-dimensional echocardiography.

Ten patients with pericardial fluid who also had striking band-like intrapericardial echoes by two-dimensional ultrasonic sector scanning are reported. Four patients had prior mediastinal radiation and four patients had severe renal disease. One patient had purulent pericarditis and one patient had traumatic hemopericardium. The two-dimensional images permitted recognition of loculation of fluid and led to the suspicion of thickened pericardial membranes. Three postradiation patients had both tamponade and constriction; tamponade alone was present in four additional patients. These data are preliminary but suggest that such findings by two-dimensional echocardiography should alert us to consider an effusive-constrictive form of pericardial disease.

Adolescent↗
PubMed1980

Echocardiography: M-mode and two-dimensional methods.

We review the basic similarities and differences of currently used M-mode and two-dimensional (2D) echocardiography. Discrete categories of disease are used to show the relative strengths of M-mode and 2D methods. The format of 2D echocardiography is well suited to analyze congenital heart disease, consequences of coronary artery disease, and distortions of anatomy due to acquired heart disease. Rapid structure movement is preserved with M-mode recording, facilitating detailed analysis of motion. The vast clinical experience with M-mode echocardiography can now be augmented by 2D echocardiography, but combination of 2D and M-mode methods is optimal for understanding each type of ultrasound recording and for best serving the patient.

Cardiomyopathies↗
PubMed1980

Mitral annular calcification: clinical and echocardiographic features.

One hundred records from patients with the single or two-dimensional echocardiographic (2DE) diagnosis of mitral annular calcification (MAC) were analyzed. 2DE manifestations of MAC included a characteristic bright structure located at the junction of the A-V groove and posterior mitral leaflet. Sixteen of the 100 patients had idiopathic hypertrophic subaortic stenosis (IHSS), a 44% (16/36) incidence in all patients with IHSS having echoes during the study period. IHSS patients with MAC were significantly older (mean 61 years vs. 43 years, p < .005) than 20 other IHSS patients without MAC studied during the same period. Both IHSS patients and non-IHSS patients with MAC had significantly lower serum calcium levels than normals or the IHSS patients without MAC. These observations support the view that the pathogenesis of MAC is related to degenerative changes from aging and increased stress on the mitral apparatus. Alterations in calcium metabolism possibly contribute to calcium deposition in the mitral annulus.

Calcinosis↗
PubMed1980

Non-invasive quantification of experimental canine myocardial infarct size using two-dimensional echocardiography.

In order to study whether wall motion abnormalities detected by two-dimensional (2D) echocardiography can be quantified and correlated with infarct size, we compared wall motion abnormalities viewed by 2D echocardiography in experimental canine infarction with post-mortem infarct size. Nineteen mongrel dogs underwent left anterior descending coronary artery snare occlusion. They were sacrificed 6 h later. Infarct sizing was done by technetium 99-m stannous pyrophosphate scintigraphy of the excised, sliced left ventricles. Fourteen dogs had both 2D echo wall motion abnormalities and infarctions. Four dogs failed to develop infarction and had no or minimal wall motion abnormalities. Inter-observer variation in 2D echocardiographic measurements was small. Wall motion abnormalities correlated with infarct size both in the 14-dog subgroup with infarction (r = 0.75, P less than 0.003) and all the 18 dogs that completed the protocol (r = 0.87, P less than 0.001). Thus, wall motion abnormalities in experimental canine myocardial infraction can be roughly quantified by 2D echocardiography and correlated with post-mortem infarct size measured by scintigraphy.

Animals↗