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Biomedical subjects

A N DeMaria

Publications and source records attributed to A N DeMaria.

At least 145 records · Page 8Linked to original sources
PubMed1987

Limitations of digital subtraction contrast echocardiography in enhancing left ventricular endocardial definition.

The purpose of this study was to evaluate whether the digital subtraction technique, applied to contrast echocardiography of the left ventricle (LV), might improve endocardial edge identification by two-dimensional echocardiography. Injections of the polysaccharide agent SHU-454 were made into the LV of five closed-chest dogs. Data were obtained at different levels of ejection fraction (EF) induced by pharmacologic or mechanical interventions and were documented by left ventriculography (VGRAM) in the right anterior oblique projection. Contrast echocardiography was recorded in the apical four-chamber view. The echocardiographic images were digitized off-line into a 256 X 256 pixel matrix with 256 gray levels/pixel. Two end-diastolic frames prior to contrast appearance were averaged to obtain a mask that was subtracted from end-diastolic contrast frames corresponding to the two beats of peak intensity. The same procedure was repeated for the systolic frames. LV edges from echocardiographic images prior to contrast appearance, from digitally subtracted echo-contrast images, and from VGRAM were traced on two occasions by two different observers. LV volumes were calculated by single-plane Simpson's rule and EF was derived by the classical equation. The intra- and interobserver reproducibility in the measurement of EF was excellent for VGRAM (r = 0.95 and 0.94, respectively), it was good for two-dimensional echocardiography (r = 0.87 and 0.73), and was fair for contrast-echo (r = 0.79 and 0.68).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1987

Contrast echo washout curves from the left ventricle: application of basic principles of indicator-dilution theory and calculation of ejection fraction.

Time-intensity curves can be obtained from contrast echocardiography of the left ventricle. The purposes of this study were: 1) to verify whether these curves conform to the basic principles of indicator-dilution theory; and 2) to derive indexes of left ventricular ejection fraction from curve analysis. In seven closed chest dogs, 31 doses of the polysaccharide agent SHU-454 were injected into the left ventricular cavity during apical four chamber two-dimensional echocardiography. Data were obtained at different levels of ejection fraction, which were induced by changes in preload, afterload and contractility, and measured by single plane Simpson's rule analysis of digital subtraction left ventriculograms. In a subset of two dogs, eight incremental doses (from 1 to 8 ml) of SHU were injected in the basal state. Contrast echocardiograms were digitized off-line, the mean gray level/pixel of a region of interest inside the left ventricular cavity was measured, and the average value for three systolic frames of each beat was used to obtain time-intensity curves. A good correlation was observed between the peak of the time-intensity curve and the quantity of contrast injected (correlation coefficient r = 0.91 by a logarithmic fit). The echo intensities observed in each animal were subsequently transformed in quantity of contrast according to these functions and their natural logarithm was calculated both with and without background subtraction. All curves relating time and the natural logarithm of the corrected intensity exhibited a descending rectilinear portion (washout) in which the correlation was very good (r = 0.97 +/- 0.02 = mean +/- SD) and which was not significantly affected by background subtraction. The validity of this fit was also unaffected by heart rate (55 to 158 beats/min) and angiographic ejection fraction (22 to 74%), and only minimally influenced by duration of contrast washout (3.3 to 14.6 seconds). Ejection fraction was calculated by an algorithm derived from indicator-dilution theory: ejection fraction = [1 - e(-bd)] X 100, where b = slope of the curve and d = cardiac cycle duration. Linear regression analysis between values of ejection fraction derived by angiography and contrast echo yielded r = 0.73. A second index, based on b and d, was derived by multiple regression analysis. Linear regression analysis of this index and angiographic ejection fraction yielded a correlation of r = 0.87.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Quantitative assessment of the hemodynamic consequences of aortic regurgitation by means of continuous wave Doppler recordings.

The purpose of this study was to evaluate the ability of continuous wave Doppler ultrasound recordings to reflect the magnitude and hemodynamic effects of aortic regurgitation. Forty-five patients with angiographically proved aortic regurgitation had Doppler studies performed within 24 hours of cardiac catheterization. High quality spectral recordings of the regurgitant jet were obtained in 31 patients, whereas 14 patients exhibited dropout of high velocity signals precluding measurement of maximal velocities. The slope of the peak to end-diastolic velocity decrease measured by Doppler examination was compared with the decay in the aortic to left ventricular diastolic pressure gradient by catheterization and was found to correlate well (r = 0.86). The Doppler velocity decay slope was generally higher in patients with angiographically severe rather than mild or moderate aortic regurgitation, but considerable overlap was present among groups. However, a diastolic velocity decay slope of greater than 3 m/s2 was seen only in those patients with advanced (3 or 4+) aortic regurgitation. Left ventricular end-diastolic pressure was estimated from the Doppler recordings by subtracting the end-diastolic pressure gradient obtained by the modified Bernoulli equation from the cuff diastolic blood pressure. A correlation was observed (r = 0.84) between Doppler and catheterization left ventricular end-diastolic pressure in the 31 patients with high quality spectral data, although the SEE was substantial (5.5 mm Hg). These data demonstrate that continuous wave Doppler recordings of the regurgitant jet can be useful in assessing the angiographic severity and hemodynamics of aortic regurgitation.

Adolescent↗
PubMed1987

Uses and limitations of exercise Doppler echocardiography in the diagnosis of ischemic heart disease.

This study tested the hypothesis that coronary artery disease might be identified by a decrease in Doppler measurements of flow velocity and acceleration. The response of aortic blood flow velocity and acceleration to exercise was determined in 102 subjects (28 young control subjects and 74 older patients) who underwent continuous wave Doppler echocardiographic examination before, during and immediately after near maximal treadmill exercise. Patients were grouped according to the results of thallium perfusion imaging: Group I = normal, Group II = ischemia with or without prior infarction and Group III = prior infarction only. A significant decrease in the level of velocity and acceleration achieved with exercise was observed both in patients in Group I (normal thallium study) (1.2 +/- 0.3 m/s and 36.8 +/- 14 m/s per s, p less than or equal to 0.005) and in patients in Group II (ischemia) (1.1 +/- 0.3 m/s and 27.7 +/- 11 m/s per s, p less than or equal to 0.0005) compared with values in young control subjects (1.4 +/- 0.2 m/s and 52.7 +/- 16 m/s per s). When groups of patients of similar age who differed in the presence (Group II) or absence (Group I) of ischemia on thallium scintigraphy were compared, no difference was found for maximal velocity (1.1 +/- 0.3 versus 1.2 +/- 0.3 m/s, p = NS), but acceleration was significantly lower in Group II (27.7 +/- 11 versus 36.8 +/- 14 m/s per s, p less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Quantitation of aortic regurgitation by computer analysis of digital subtraction angiography.

Digital subtraction angiography provides the potential to determine aortic regurgitant fraction by computer analysis of time-intensity curves generated from regions of interest positioned over the aorta and left ventricle after aortography. To validate this ability, we studied six dogs instrumented with an electromagnetic flow probe on the ascending aorta. Aortic regurgitation of varying severity was produced by a basket catheter introduced through the right carotid artery. Aortograms were performed using continuous fluoroscopy at 30 frames/s and stored in digital format in a 256 x 256 pixel matrix. An image-processing computer was utilized to plot summated pixel intensity versus time for both the aortic and the left ventricular regions of interest. Regurgitant fraction was calculated from the time-intensity curves using an algorithm analogous to that employed by dye-dilution methods. Regurgitant fraction determined from digital angiography was compared with that obtained by electromagnetic flow and was found to correlate well (r = 0.94, SEE = 7.4%) over a wide range of values. Thus, these data indicate that aortic regurgitant fraction can be accurately determined from computer analysis of digitally acquired aortograms in an animal model of acute aortic regurgitation.

Animals↗
PubMed1987

Cardiovascular disease in the elderly. Clinical assessment.

The elderly patient with suspected cardiovascular disease poses a diagnostic challenge to the clinician. In many elderly patients the frequent unreliability of the history and the presence of multiple concurrent diseases and medications complicate accurate assessment of the patient's cardiac problem. Clinical laboratory and noninvasive cardiac techniques are now available that enhance the accuracy of cardiac diagnosis and aid in the evaluation of left ventricular function.

Aged↗
PubMed1987

A double-blind comparison of lisinopril with captopril in patients with symptomatic congestive heart failure.

Angiotensin-converting enzyme (ACE) inhibition with captopril is accepted therapy for the treatment of symptomatic congestive heart failure. In this trial, we compared the new ACE inhibitor, lisinopril, to captopril during a 12-week randomized double-blind study. One hundred twenty-nine patients with New York Heart Association class II, III, or IV congestive heart failure were randomized to receive either lisinopril 5 mg/day (n = 64) or captopril 37.5 mg/day (n = 65) in 15 centers. Drug doses could be titrated upwards every 4 weeks. The primary measure of drug efficacy was improvement in treadmill exercise time using a modified Naughton protocol. Secondary measures of efficacy and the development of adverse effects were also examined. Lisinopril improved exercise time (following 12 weeks of therapy) more than captopril [from 500 +/- 30 to 682 +/- 34 sec (mean +/- SEM) with lisinopril versus 480 +/- 26 to 600 +/- 35 sec with captopril; difference between groups, p less than 0.05]. Adverse drug effects were unusual and similar in frequency in the two groups, although an increase in blood urea nitrogen was more common with lisinopril than with captopril (p less than 0.05). These results indicate that using the doses and treatment regimens studied, lisinopril is more effective than captopril for the treatment of symptomatic congestive heart failure. Adverse experiences with lisinopril were infrequent and similar in incidence to those observed with captopril.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1986

Systematic correlation of continuous-wave Doppler and hemodynamic measurements in patients with aortic stenosis.

The purpose of this study was to compare estimates of pressure gradients obtained from continuous-wave (CW) Doppler recordings with direct pressure measurements derived from cardiac catheterization in patients with aortic stenosis. Forty patients who underwent cardiac catheterization for evaluation of aortic stenosis were prospectively studied with CW Doppler spectral recordings of the aortic valve prior to catheterization. Thirty-three patients underwent a second Doppler examination simultaneously with pressure recordings in the catheterization laboratory. Nineteen of the patients had catheterization pressures measured using high-fidelity, micromanometer-tip catheters. Doppler and pressure tracings were digitized using a microprocessor-based computer with a software program which allowed for calculation of maximal instantaneous, mean, and peak-to-peak gradients, plus ejection and acceleration times. Maximal instantaneous gradient by CW Doppler showed an excellent correlation with maximal instantaneous catheterization gradient (r = 0.93, SEE = 9 mm Hg). The correlation of maximal instantaneous Doppler gradient with peak-to-peak catheterization gradient was also linear (r = 0.85, SEE = 12 mm Hg), but there was a consistent overestimation of peak-to-peak gradient in 38 of 40 cases (mean = 17 mm Hg). Mean gradient as calculated by the two techniques correlated best of all measurements performed (r = 0.95, SEE = 6 mm Hg). When patients were grouped into subsets of mild (0 to 25 mm Hg), moderate (25 to 50 mm Hg), and severe (greater than 50 mm Hg) levels of stenosis, the correlation of maximal instantaneous Doppler and peak-to-peak catheterization gradients were r = 0.22, 0.44, and 0.77, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Assessment of left ventricular diastolic function: comparison of Doppler echocardiography and gated blood pool scintigraphy.

Although left ventricular diastolic filling patterns can be examined by both Doppler velocity recordings and gated blood pool scintigraphy, few data exist regarding a comparison of these techniques. Therefore, Doppler echocardiography and scintigraphy were compared in 25 patients. Pulsed Doppler echocardiography was performed using an apical four chamber view with the sample volume at the level of the mitral anulus. Doppler measurements included peak velocity of the early diastolic filling wave, time to peak early diastolic velocity from both end-systole and end-diastole, diastolic time period and diastolic integrated velocity (early, atrial and total). The cross-sectional area of the mitral anulus and the left ventricular end-diastolic volume were estimated from measurements made on the apical four chamber view. Scintigraphic measurements included normalized peak filling rate, time to normalized filling rate from both end-diastole and end-systole, diastolic time period and relative diastolic filling during early and atrial filling. Doppler echocardiography and scintigraphy compared favorably in assessment of fractional filling during early diastole (r = 0.84) and atrial systole (r = 0.85), ratio of early to atrial filling (r = 0.83), diastolic filling period (r = 0.94) and interval from end-diastole to peak early diastolic flow (r = 0.88). Normalized peak filling rate and time to normalized peak filling rate from end-systole did not correlate closely by these two techniques. The differences in normalized peak filling rate may be explained by difficulties in estimating mitral anulus cross-sectional area and left ventricular end-diastolic volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Comparative accuracy of two-dimensional echocardiography and Doppler pressure half-time methods in assessing severity of mitral stenosis in patients with and without prior commissurotomy.

This study was undertaken to compare the accuracies of the two-dimensional echocardiographic (2DE) and Doppler pressure half-time methods for the noninvasive estimation of cardiac catheterization measurements of mitral valve area in patients with pure mitral stenosis both with and without a previous commissurotomy. Data were retrospectively obtained from 74 consecutive patients who underwent cardiac catheterization within a 30 month period for evaluation of mitral stenosis, and who had two-dimensional echocardiograms performed before catheterization. Six patients (8.1%) had technically inadequate 2DE images and their data were excluded from analysis. Two of these patients had undergone commissurotomy, while the remaining four had not. Continuous-wave Doppler echocardiographic examinations were attempted in 45 patients and adequate measurements of pressure half-times were obtained in all patients studied. Mitral valve area by two-dimensional echocardiography was measured as the planimetered area along the inner border of the smallest mitral orifice visualized during short-axis scanning, while pressure half-time was calculated as the interval between the peak transmitral velocity and velocity/square root 2 as measured from the envelope of the Doppler spectral signal. Calculations from catheterization represented the minimal valve area at rest as derived from the Gorlin formula with the use of pressure gradients and thermodilution measurements of cardiac output. Thirty-seven of the patients had had a previous mitral commissurotomy a mean of 11.2 +/- 5.4 years before, while the remaining 37 patients were previously unoperated. Mean valve area as determined at catheterization for the total group of patients ranged from 0.37 to 2.30 cm2 (mean = 1.08 +/- 0.42 cm2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Value and limitations of computer analysis of digital subtraction angiography in the assessment of coronary flow reserve.

Conventional coronary angiography has significant limitations in quantifying the severity and functional significance of coronary stenoses. However, coronary reactive hyperemia is an excellent physiologic indicator of coronary reserve. Digital subtraction angiography offers the potential to analyze coronary blood flow dynamics quantitatively. Therefore we assessed the accuracy of digital angiographic methods to detect and quantify reductions in coronary flow reserve secondary to stenoses of varying magnitude in an experimental canine preparation. Studies were performed in nine anesthetized open-chest dogs with an electromagnetic flow (EMF) probe and two pneumatic occluders positioned on the left circumflex coronary artery. One occluder served to induce reactive hyperemia by temporary total occlusion, while the other served to produce variable gradations of stenosis. Digital angiography was performed after the subselective injection of contrast under basal conditions and during reactive hyperemia. Time-intensity curves were obtained from digital angiograms for both a coronary and a myocardial region of interest. Measurements included area under the curve, time to peak contrast, and contrast disappearance rate. An index of coronary reserve was computed as the ratio of hyperemic to basal measurements for each of these methods. Coronary blood flow ranged from 6.5 to 142 ml/min, with hyperemic to basal EMF flow ratios of 0.80 to 4.2:1. The index derived from contrast decay rate showed a poor correlation with EMF (r = .34). The correlation between measurements of time to peak myocardial contrast and coronary blood flow was r = .68 (y = 0.16 x + 0.97). The area under the time-intensity curve from a coronary region of interest showed a close correlation with coronary blood flow (y = 0.91 x + 0.1, r = .86). Thus estimates of coronary reserve by computer analysis of digital subtraction angiograms can yield information regarding the physiologic consequences of coronary stenoses.

Angiography↗
PubMed1986

Detection of aortic insufficiency by standard echocardiography, pulsed Doppler echocardiography, and auscultation. A comparison of accuracies.

To determine the relative sensitivity and specificity of noninvasive methods for detecting aortic insufficiency, we compared the accuracy of auscultation, echocardiography, and pulsed Doppler echocardiography in detecting aortic insufficiency in 106 patients in whom the presence or absence of the lesion was shown by supravalvular aortography. The sensitivity and specificity for the diagnosis of aortic regurgitation was 96% and 96% for pulsed Doppler echocardiography, 73% and 92% for auscultation, 43% and 91% for two-dimensional echocardiography, 46% and 81% for anterior mitral leaflet flutter, and 9% and 96% for ventricular septal flutter, respectively. Auscultation was more sensitive than either M-mode or two-dimensional echocardiography in the diagnosis of aortic insufficiency (p less than 0.01). Pulsed Doppler echocardiography was significantly more sensitive than auscultation (p less than 0.0001) and was positive in 19 patients in whom no murmur was found. Thus, pulsed Doppler echocardiography is the optimal noninvasive marker for aortic insufficiency.

Adolescent↗
PubMed1985

Assessment of the severity of valvular regurgitation by digital subtraction angiography compared to cineangiography.

The purpose of this study was to evaluate whether the degree of valvular regurgitation could be reliably estimated by digital subtraction angiography using a 0 to 4+ scale of measurement identical to that applied in conventional cineangiography. Thirty-seven sets of angiograms, each consisting of a digital subtraction angiogram (DSA) and a cineangiogram (CINE) were obtained from 33 patients. Twenty-three angiogram sets were obtained from the ventricles, while 14 were performed in the ascending aorta. Both DSA and CINE images were analyzed for regurgitation by two independent observers. A weighted kappa statistical analysis, carried out to determine the extent to which the two observers agreed on DSA and CINE assessments, demonstrated excellent agreement. The degree of atrioventricular valve regurgitation manifested by DSA was not significantly different from that determined on CINE for either Observer A or B (1.8 +/- 1.2 by CINE vs 2.1 +/- 1.5 by DSA, 2.1 +/- 1.4 vs 2.5 +/- 1.0, respectively). However, occasional exceptions occurred in which the degree of atrioventricular valve regurgitation was overestimated by DSA as compared to CINE. Conversely, in 12 cases with aortic regurgitation, DSA overestimated the grade of regurgitation compared to CINE, 2.3 +/- 1.1 by CINE vs 3.2 +/- 0.8 by DSA (p less than 0.01) for Observer A and 2.1 +/- 1.2 vs 3.0 +/- 1.0 (p less than 0.01) for Observer B. The phenomenon which best explains these data is the occurrence of digital enhancement of myocardial opacification produced by coronary perfusion radiocontrast during angiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗