Peak filling rate normalized to mitral stroke volume: a new Doppler echocardiographic filling index validated by radionuclide angiographic techniques.

The noninvasive measurement of left ventricular filling has relied predominantly on radionuclide-derived peak filling rate normalized to end-diastolic volume. Doppler echocardiography also has the ability to measure peak filling rate, but wide application of this technique has been limited by technical errors involved in quantitative echocardiographic determination of mitral anulus cross-sectional area and ventricular volumes. For Doppler echocardiography, normalization of peak filling rate to mitral stroke volume rather than end-diastolic volume permits the derivation of a diastolic filling index that is relatively free of errors caused by geometric assumptions, diameter measurements and sample volume positioning. This normalization process can be achieved by simply dividing early peak filling velocity by the time velocity integral of mitral inflow. To validate this new Doppler echocardiographic filling index, Doppler echocardiographic and radionuclide-derived peak filling rate, both normalized to mitral stroke volume, were compared in 30 patients; there was an excellent correlation (r = 0.91, SEE = 0.88). This variable was not influenced by the position of the sample volume in relation to the mitral apparatus in contrast to early filling velocity, which increased 37%, and early/late filling (E/A) ratio, which increased 43% as the sample volume was moved from the anulus to the tips of the mitral leaflets. In a cohort of 22 normal patients, the mean peak filling rate normalized to mitral stroke volume (SV) was 5.25 +/- 1.47 SV/s. The mean peak filling rate for a subgroup of eight normal patients aged 57 to 89 years (mean 71 +/- 9) was 3.9 +/- 1 SV/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Silent ischemia during coronary occlusion produced by balloon inflation: relation to regional myocardial dysfunction.

Thirty patients with stable exertional angina undergoing percutaneous transluminal coronary angioplasty of an isolated obstructive lesion of the proximal left anterior descending artery were prospectively evaluated to investigate the relation between angina induced by balloon inflation and the quantity and severity of myocardial ischemia as determined by electrocardiographic (ECG) monitoring and by echocardiographic assessment of regional and global left ventricular wall motion. Anginal pain interviews, continuous two-dimensional echocardiographic recordings and 12 lead ECG recordings at 10 second intervals were obtained for the first two inflation sequences. Seventeen patients had angina with both inflations (symptomatic group), seven patients had no angina or related symptoms during either inflation (asymptomatic group) and six patients had both painful and painless inflations (mixed response group). Comparison of the three groups revealed that they did not differ in mean age, sex distribution, prior history of angina or the incidence of comorbid conditions. Echocardiographic measurements of global and regional left ventricular dysfunction during balloon inflation were comparable in the symptomatic and asymptomatic groups. Similarly, there were no significant differences in the time to onset or magnitude of ST segment changes. The results of the wall motion and ECG studies in the mixed response group paralleled the results in the symptomatic and asymptomatic groups, with no significant differences in any of the variables measured between the painful and painless inflations. These data demonstrate that silent myocardial ischemia occurs in an appreciable proportion of patients during coronary angioplasty and the absence of angina does not imply that a lesser amount of myocardium is jeopardized than with painful inflations.

Regional myocardial dysfunction during coronary angioplasty: evaluation by two-dimensional echocardiography and 12 lead electrocardiography.

Balloon inflation performed during percutaneous transluminal coronary angioplasty causes transient total occlusion of the coronary artery and thus provides a model for evaluation of the regional myocardial responses to transient ischemia. Twenty patients with normal left ventricular function undergoing angioplasty of isolated stenosis of the proximal left anterior descending coronary artery were studied. In group A (14 patients) analysis of one inflation-deflation sequence per patient was performed. Group B (six patients) had multiple (greater than 5) inflations; the first and last sequences were analyzed. Assessment included continuous two-dimensional echocardiography with computerized quantitative analysis of regional left ventricular wall motion, and continuous 12 lead electrocardiographic recordings. The mean duration of inflation in group A was 62 +/- 6 seconds (mean +/- SD). The onset of regional left ventricular dysfunction was 12 +/- 5 seconds after inflation. Profound dysfunction was noted in all patients. After 60 seconds of balloon occlusion of the coronary artery, 29% of patients had severe hypokinesia of the ischemic region and 71% had akinesia or dyskinesia. With deflation there was prompt recovery of regional function, with full recovery at 43 +/- 17 seconds. Comparison of data from first and last inflations in group B revealed no significant differences in time to onset of dysfunction, magnitude of dysfunction or time to complete recovery of function. The onset of ischemic electrocardiographic changes lagged behind the onset of wall motion abnormalities, with only 64% of patients showing evidence of ischemia on 12 lead electrocardiograms at 20 seconds of inflation. After 60 seconds, 86% had ischemia detectable by electrocardiography. Thus, balloon inflation during coronary angioplasty leads to profound but reversible regional left ventricular dysfunction. Repeated occlusions of the coronary artery during angioplasty do not have a cumulative ischemic effect. It may be hazardous to apply these findings to patients who have underlying major left ventricular dysfunction and in whom the reversibility of dysfunction and lack of cumulative ischemic effect may not be assured.

Echocardiographic studies of the human fetus: prenatal diagnosis of congenital heart disease and cardiac dysrhythmias.

During obstetrical ultrasound examinations, 200 M-mode and 35 real-time two-dimensional echocardiographic studies were performed on 180 fetuses of high-risk pregnancies. Fetal gestational ages ranged from 18 to 41 weeks. M-mode "sweeps" demonstrating mitral- and septal-aortic fibrous continuity were obtained in 115 studies. Paradoxic septal motion in 50 fetuses suggested relarive right ventricular volume loading. Congenital cardiac malformations were accurately diagnosed in a 34-week fetus with pulmonary atresia and hypoplastic right ventricle and in a 28-week fetus with a univentricular heart. Congenital complete atrioventricular block was diagnosed in a 28-week fetus and atrial flutter with variable atrioventricular block was diagnosed in a 38-week fetus. The use of echocardiographic studies to evaluate cardiac structure and rhythm in utero assists in counseling prospective parents and in planning postnatal management for their offspring.

Dynamics of early and late left ventricular filling determined by Doppler two-dimensional echocardiography during percutaneous transluminal coronary angioplasty.

To study the influence of ischemia on both early and late left ventricular filling, Doppler 2-dimensional echocardiography was used to measure filling parameters during percutaneous transluminal coronary angioplasty (PTCA) in 26 patients. Doppler recordings were taken immediately before balloon inflation and continuously during balloon inflation and deflation until 60 seconds into the recovery period. During PTCA of the left anterior descending artery (16 patients) there was a 35% decrease in early peak filling rate from 269 +/- 88 to 169 +/- 55 ml/s (p less than 0.0005) by 60 seconds of balloon inflation. In patients undergoing PTCA of the left circumflex (4 patients) or dominant right coronary artery (6 patients), the early peak filling rate decreased 15% from 325 +/- 126 to 284 +/- 137 ml/s (p less than 0.005). The decrease in early peak filling rate became evident at approximately 15 seconds after balloon inflation and fully recovered 20 seconds after balloon deflation. Rather than an expected increase in atrial stroke volume and a decrease in early to late filling ratio during coronary occlusion, there was a 28% decrease in atrial stroke volume during left anterior descending coronary artery PTCA and a 6% decrease during right coronary and circumflex PTCA. Because of the simultaneous decrease in both early and late ventricular filling, peak early to late filling ratio was only slightly altered during PTCA. There was an 83% increase in mean pulmonary artery wedge pressure during balloon inflation from 12 +/- 5 to 20 +/- 4 mm Hg. In 11 of these patients global systolic function was measured on subsequent inflations during PTCA using 2-dimensional echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolic and functional effects of perfluorocarbon distal perfusion during coronary angioplasty.

Myocardial lactate metabolism and left ventricular function were studied in 12 patients during angioplasty of the left anterior descending artery performed with distal coronary perfusion (oxygenated and nonoxygenated Fluosol) and by conventional technique without distal perfusion. Before balloon inflation there was net lactate extraction by the heart (31 +/- 6%). During balloon inflations performed with distal perfusion there was net lactate release into the great cardiac vein while the balloon was inflated; the great cardiac vein lactate concentration was approximately 25% lower during perfusion with oxygenated versus nonoxygenated Fluosol (p less than 0.02) indicating less myocardial lactate release. After balloon deflation washout of lactate into the great cardiac vein (net myocardial release) was observed in all 3 protocols. Left ventricular ejection fraction measured by echocardiography decreased markedly during nonperfused (53 +/- 3 to 36 +/- 3%, p less than 0.001) and nonoxygenated Fluosol (52 +/- 2 to 30 +/- 3%, p less than 0.001) inflations. This dysfunction was largely prevented by oxygenated Fluosol where only a minimal decrease in ejection fraction (51 +/- 2 vs 48 +/- 2%, p less than 0.02) occurred. Analysis of regional contractile function yielded similar results. Although oxygenated perfluorocarbons decrease cardiac lactate release during angioplasty, this study provides evidence for the onset of lactate production even when ventricular function is preserved.

Comparison and reproducibility of visual echocardiographic and quantitative radionuclide left ventricular ejection fractions.

Left ventricular (LV) ejection fraction (EF) is commonly assessed by equilibrium radionuclide angiography and echocardiography. These methods are presumed to be interchangeable for this purpose. This study (1) compares quantification of LVEF by equilibrium radionuclide angiography with visual estimation of LVEF by echocardiography, (2) determines the reproducibility of both methods, and (3) evaluates whether differences in determinations of LVEF are of clinical relevance. Seventy-three clinically stable patients had both equilibrium radionuclide angiography and echocardiography performed within a 4-day period. LVEF by both techniques was compared after blinded analysis by 3 echocardiographers and 3 nuclear technologists. Reproducibility was assessed by blinded repeat analysis after a 1-week interval. The frequency of differences in repeat assessments of EF that the authors considered to be of potential clinical relevance (i.e., difference > or = 10% EF units) was assessed for both techniques. Correlation of LVEF determined by both methods was good (r = 0.81, SEE = 3.5) but with substantial differences in individual patients (limits of agreement, 23.6%). Intra- and inter-observer reproducibility was good for both methods, but better for radionuclide LVEF than for echocardiographic LVEF. Limits of agreement were substantially better for radionuclide LVEF than for echocardiographic LVEF (1.8% to 3.6% versus 13.4% to 17.4%, respectively). Clinically relevant differences did not occur on repeat processing of equilibrium radionuclide angiography. In contrast, potentially clinically relevant differences occurred in 8% to 26% of studies on repeat analysis of echocardiography. Thus, LVEF determined by equilibrium radionuclide angiography and echocardiography show good agreement. Both methods provide clinically valuable measurements for LV function. However, when a precisely reproducible measurement is required for patient management decisions, equilibrium radionuclide angiography is the method of choice.

Reduction of myocardial ischemia during percutaneous transluminal coronary angioplasty with oxygenated Fluosol.

The effects of perfusion of an oxygen-carrying perfluorochemical emulsion (Fluosol) in alleviating symptoms of myocardial ischemia during balloon occlusion were examined in a multicenter trial of 245 patients. Severe anginal pain occurred less frequently in patients receiving Fluosol perfusion (21%) than in those receiving routine angioplasty (34%) (p less than 0.05). ST-segment changes at balloon deflation in routine angioplasty patients were significantly greater than in patients who received oxygenated Fluosol perfusion (2.2 +/- 1.2 vs 1.7 +/- 0.9 mm; p less than 0.03). Profound regional wall dysfunction (-561 +/- 224 U) was observed in routine angioplasty patients by 2-dimensional echocardiography. Patients receiving oxygenated Fluosol perfusion, however, maintained near baseline levels of ventricular function (-61 +/- 335 U) during occlusion (p less than 0.0001). Mean global left ventricular ejection fraction was preserved at baseline levels during balloon inflation in patients perfused with oxygenated Fluosol but decreased significantly (p less than 0.001) during occlusion in routine angioplasty patients. A total of 26 complications (19 routine group; 7 perfusion group) was reported. Adverse responses to the perfusate were infrequent, occurring in 1.6 and 2.0% of patients after the test dose and during perfusion, respectively. Thus, transcatheter perfusion with an oxygen-carrying perfluorochemical emulsion is effective in alleviating myocardial ischemia during angioplasty and can be safely administered in this patient population.

Fetal echocardiography. A tool for evaluation of in utero cardiac arrhythmias and monitoring of in utero therapy: analysis of 71 patients.

Fetal echocardiographic studies were performed in 71 patients referred for evaluation of cardiac rhythm disturbances at 24 to 40 weeks' gestation. After 2-dimensional echocardiographic study of cardiac structure was performed, M-mode echocardiograms were analyzed for measurement of cardiac rate, atrioventricular contraction sequence, atrioventricular valve motion, and duration of postectopic pauses. Arrhythmias were diagnosed in 59 patients. In 34 patients with isolated ectopic beats, the arrhythmia resolved during later pregnancy in 26 or within the first 5 days of life in 8. Six patients had mild sinus bradycardia and 8 had frequent sinus pauses; all 14 had resolution of the arrhythmia during pregnancy. Sustained arrhythmias occurred in 11 patients. Deaths occurred when there was associated fetal congestive heart failure (hydrops fetalis), structural heart disease, or both. M-mode echocardiography diagnosed supraventricular tachycardia in 3 fetuses. The echocardiogram was used thereafter for monitoring transplacental digoxin therapy.

Medical imaging databases. A National Institutes of Health workshop.

Development and implementation of a medical imaging database in a PACS-type environment that integrates all the patient data will impact directly on the quality of patient care. In addition, access to the wealth of information that is simply not accessible through the current technology, will contribute to improved disease detection and improved patient treatment, as well as produce significant new medical knowledge. Research and implementations must proceed in interdisciplinary environments which successfully combine the expertise and knowledge from the medical community with that of the database and computer science disciplines.

Physical parameters affecting the visibility of small ventricular septal defects using two-dimensional echocardiography.

We report a study showing that two-dimensional echocardiography is capable of visualizing a ventricular septal defect as small as 3 mm. The physical parameters which determine the visibility of an aperture in the myocardium include the presence of anterior refractile tissue, the amount of ultrasound beam focusing and range over which this occurs, the angle of incidence of the ultrasound beam on the septum, and the number of lines of information per degree of sector sweep. These factors are illustrated by in vitro tests. The influence of operator controllable variables in two-dimensional sector scanning echocardiography is discussed.

Brominated radiopaque liposomes: contrast agent for computed tomography of liver and spleen: a preliminary report.

Contrast enhancement of liver and spleen in the dog was obtained after intravenous administration of brominated radioopaque liposomes (ROL) (1-5 micron in diameter. Computed tomographic (CT) numbers generated before and after 3 hours of ROL administration demonstrated an increase in hepatic attenuation. ROL are biodegradable lipid vesicles that can be subjected to further physicochemical modifications (size, charge composition) that alter their biodistribution and pharmacokinetics. These changes can result in improved hepatosplenic contrast enhancement.

Medical image databases: a content-based retrieval approach.

Information contained in medical images differs considerably from that residing in alphanumeric format. The difference can be attributed to four characteristics: (1) the semantics of medical knowledge extractable from images is imprecise; (2) image information contains form and spatial data, which are not expressible in conventional language; (3) a large part of image information is geometric; (4) diagnostic inferences derived from images rest on an incomplete, continuously evolving model of normality. This paper explores the differentiating characteristics of text versus images and their impact on design of a medical image database intended to allow content-based indexing and retrieval. One strategy for implementing medical image databases is presented, which employs object-oriented iconic queries, semantics by association with prototypes, and a generic schema.

Quantitative flow measurements with Doppler ultrasound: techniques, accuracy, and limitations.

Using Doppler ultrasound, blood-filled structures appearing on a real-time ultrasound image may be interrogated for flow information. Quantitation of the Doppler signal may yield estimates of instantaneous and time-averaged velocity, volume flow rate, and pressure difference. In this article, the techniques of signal analysis used are discussed, together with the sources of error that confront their clinical application.

Educational challenges.

Despite the efforts of some educators, computers and electronic networks have yet to achieve their proper role in education. Advances, such as more intuitive software, CD-ROM media, and networks, offer powerful new tools, but technology is only one facet of instructional design. Much like effective authors of print media, software designers must adhere to certain principles that seem to underpin all successful computer-assisted instruction.

A radiographic and echocardiographic approach to cyanotic congenital heart disease.

An updated, systematic approach to the diagnosis of cyanosis in the infant or child has been presented. It involves the use of clinical data (to establish the presence of cyanosis), radiographic information (to assess lung parenchyma, pulmonary vascularity, and certain key, border-forming, cardiac structures), and M-mode and cross-sectional echocardiographic data (the source of detailed intracardiac anatomic information). Specific radiographic and echocardiographic features of the 10 most common cyanotic congenital heart lesions have been presented. Using this approach, one should be able to diagnose accurately the cyanotic infant or child. Further planning for cardiac catheterization and angiocardiography can then be accomplished with an informed and rational point of view.

Computerized tomographic demonstration of a retroperitoneal hematoma causing femoral neuropathy. Report of two cases.

To the previously reported 28 cases of femoral neuropathy caused by a retroperitoneal hematoma in patients on anticoagulant drugs are added two cases in which the diagnosis was made by direct visualization of hematoma of the iliacus muscle by computerized tomography of the abdomen.

Echocardiography of the right side of the heart.

Echocardiography has not only revealed the morphologic aspects of the right-sided cardiac structure but has, through the use of pulsed and color Doppler imaging, provided a whole new level of certainty in the diagnosis of cardiac disease. The structure and function of the right-sided chambers are now far better appreciated since this technique has become more widely used for early clinical diagnosis of right-sided cardiac disease.

Evaluation of gynecologic pelvic masses by ultrasound and computed tomography.

In a prospective study, computed tomography (CT) and ultrasound scanning of the pelvis were performed for 50 patients having clinically suspected pelvic masses or recurrence of known pelvic malignancy. On the basis of these scan images, an attempt was made to characterize pelvic masses on the basis of benign or malignant character and organ of origin. The presence of recurrent tumor in patients previously treated for pelvic malignancy was assessed, and the presence of abdominal metastatic disease was evaluated for all patients. CT was successful in a higher proportion of cases in detecting abdominal metastatic disease due to bowel gas's degrading the abdominal ultrasound scan images. In characterizing suspected pelvic masses and evaluating the presence of recurrent tumor, both CT and ultrasound scanning were accurate in approximately two-thirds of cases. The significant proportion of incorrect results indicates that neither technique is sufficiently accurate to preclude pathologic diagnosis of a pelvic mass or to substitute for exploratory surgery to assess recurrence of pelvic malignancy.

Medical image collection indexing: shape-based retrieval using KD-trees.

The capacity to retrieve images containing objects with shapes similar to a query shape is desirable in medical image databases. We propose a similarity measure and an indexing mechanism for non-rigid comparison of shape which adds this capability to image databases. The (dis-)similarity measure is based on the observations that: (1) the geometry of the same organ in different subjects is not related by a strictly rigid transformation; and (2) the orientation of the organ plays a key role in comparing shape. We propose a similarity measure that computes a non-rigid mapping between curves and uses this mapping to compare oriented shape. We also show how KD-trees can index curves so that retrieval with our similarity measure is efficient. Experiments with real-world data from a database of magnetic resonance images are provided.