Biomedical subjects

J A Rumberger

Publications and source records attributed to J A Rumberger.

At least 55 records · Page 3Linked to original sources

PubMed1995

Coronary artery calcium area by electron-beam computed tomography and coronary atherosclerotic plaque area. A histopathologic correlative study.

BACKGROUND: Coronary calcium identified by electron-beam computed tomography (EBCT) correlates poorly with luminal atherosclerotic narrowing, but calcium, an intimate part of coronary plaque, may be more directly related to atheromatous plaque area. METHODS AND RESULTS: Thirty-eight coronary arteries from 13 autopsy hearts were dissected, straightened, and scanned with EBCT in 3-mm contiguous increments. Coronary calcium area was defined as one or more pixels with a density > 130 Hounsfield units (0.18 mm2/pixel). Each artery was divided into corresponding 3-mm segments, representative histological sections were stained, and atherosclerotic plaque area per segment (mm2) was quantified. Coronary artery calcium and coronary artery plaque areas were correlated for the hearts as a whole, for individual coronary arteries, and for individual coronary artery segments. The sums of histological plaque areas versus the sums of calcium areas were highly correlated for each heart and for each coronary artery. However, coronary plaque area was on the order of five times greater than calcium area. Furthermore, minimal diffuse segmental coronary plaque could be present despite the absence of coronary calcium detectable by EBCT. CONCLUSIONS: This histopathologic study confirms an intimate relation between whole heart, coronary artery, and segmental coronary atherosclerotic plaque area and EBCT coronary calcium area but suggests that there is a threshold value for plaque area below which coronary calcium is either absent or not detectable by this methodology.

Adult↗

PubMed1995

Relation of initial infarct size to extent of left ventricular remodeling in the year after acute myocardial infarction.

OBJECTIVES: This study attempted to determine the relation between infarct size after acute myocardial infarction and subsequent left ventricular remodeling using precise clinical measurements. BACKGROUND: Animal studies have demonstrated that the degree of left ventricular remodeling after myocardial infarction is linearly related to infarct size. Clinical studies have not clearly replicated these results because of imprecise measurements and failure to adjust for patency of the infarct-related artery. METHODS: Infarct size was measured from technetium-99m (Tc-99m) sestamibi perfusion images in 14 patients (12 with an anterior, 2 with an inferior infarction) by a threshold method previously described and expressed as percent of the left ventricle (32 +/- 17% left ventricle [mean +/- SD], range 6% to 58%). Absolute end-systolic volume, end-diastolic volume and ejection fraction were determined by electron beam computed tomographic images performed at discharge and at 6 weeks, 6 months and 1 year after myocardial infarction. All patients had documented infarct-related artery patency after reperfusion therapy. RESULTS: At hospital discharge, there was no correlation between infarct size and end-systolic and end-diastolic volumes or ejection fraction. There was significant left ventricular dilation in the study group over the next year. As remodeling progressed, there was closer correlation between infarct size and ejection fraction and end-systolic volume measures (infarct size vs. end-systolic volume, from r = 0.43 at discharge to r = 0.80 at 1 year; infarct size vs. ejection fraction, from r = -0.39 at discharge to r = -0.84 at 1 year). There was a strong inverse correlation between infarct size at discharge and subsequent changes over the next year in end-systolic volume (r = 0.63, p = 0.02) and ejection fraction (r = -0.66, p = 0.01). CONCLUSION: Infarct size as measured by Tc-99m sestamibi at hospital discharge after an index infarction is predictive of subsequent change in left ventricular volume and function in the year after myocardial infarction. Patients with a large infarct demonstrated the greatest degree of dilation in the setting of patency of the infarct-related artery.

Adult↗

PubMed1995

Quantification of coronary artery calcium by electron beam computed tomography for determination of severity of angiographic coronary artery disease in younger patients.

OBJECTIVES: This study attempted to 1) evaluate five quantitative measures of coronary artery calcium and determine which best agreed with coronary artery disease severity at angiography; and 2) determine optimal quantity cutpoints to distinguish among no, mild and significant disease. BACKGROUND: Coronary artery calcium identified noninvasively by electron beam computed tomography is a sensitive marker for atherosclerosis. Quantitative assessments of calcium could distinguish among patients with no, mild and significant disease in clinical, screening and research settings. METHODS: One hundred sixty patients, 23 to 59 years old, underwent coronary angiography and electron beam computed tomography. Coronary artery calcium was defined as dense (> 130 Hounsfield units) foci > or = 2 mm2 on the tomogram. Regression and receiver operating characteristic analyses were used to evaluate five quantitative measures of calcium as predictors of the largest stenosis in the coronary arteries and to identify optimal cutpoints for distinguishing among disease categories. No disease was defined as no stenosis, mild disease as 10% to 49% diameter stenosis in one or more major branches and significant disease as > or = 50% diameter stenosis in one or more major branches. RESULTS: All measures evaluated performed well. With calcific area as the quantitative measure, the best cutpoint for discriminating between patients with and without disease was the presence of calcium: sensitivity 81%, specificity 86% and overall accuracy 83%. The best cutpoint for discriminating between patients with and without significant disease was 18 mm2: sensitivity 86%, specificity 81% and accuracy 83%. CONCLUSIONS: Because the ranges of calcium quantity overlapped across disease categories, no cutpoints would distinguish among categories with absolute certainty. However, selected cutpoints could rule out disease in most healthy subjects and identify most patients with significant disease.

Adult↗

PubMed1995

Coronary calcium, as determined by electron beam computed tomography, and coronary disease on arteriogram. Effect of patient's sex on diagnosis.

BACKGROUND: Coronary artery calcium identified by electron beam computed tomography (EBCT) has potential for noninvasive localization of coronary atherosclerotic disease. However, the effect of a patient's sex on its diagnostic capability has not been examined in a clinical population. METHODS AND RESULTS: Fifty women and 89 men had EBCT scans done an average of 1 day after coronary arteriography. Maximum arteriographic percent luminal diameter stenosis of any artery was paired with the total EBCT coronary calcium score for each subject. The women (age, 56 +/- 11 years [mean +/- SD]) were older than the men (age, 47 +/- 7 years), but the subjects were matched for indications for arteriography and extent of disease as assessed by arteriography. Sensitivity, specificity, and positive and negative predictive values for coronary calcium were nearly identical for men and women, regardless of the degree of arteriographic disease. EBCT was highly sensitive to the presence of arteriographic disease (range, 94% to 100%), but had only moderate specificity (57% to 66%) for significant disease (> or = 50% stenosis) and low specificity (35% to 38%) for any arteriographic disease (> 0% stenosis). Negative predictive values in men and women ranged from 79% to 91% for any arteriographic disease and from 95% to 100% for significant disease, respectively. Numerical calcium scores were significantly different between subjects with normal arteriograms and those with significant disease; however, calcium score had limited power to separate trivial, moderate, and significant disease. Receiver operating characteristic curve areas, determined as an extension of the analyses of sensitivity and specificity, were high for EBCT-defined calcium scores for both any arteriographic disease and significant arteriographic disease, and were not different between the sexes. CONCLUSIONS: In a middle-aged population, noninvasive definition of coronary calcium by EBCT has similar predictive value for arteriographic coronary artery disease in men and women.

Calcinosis↗

PubMed1995

Aprotinin for coronary artery bypass grafting: effect on postoperative renal function.

Two hundred sixteen patients undergoing coronary artery bypass graft procedures were randomized to receive either high-dose aprotinin or placebo. Clinically important postoperative renal insufficiency was infrequent, with a single patient (0.9%) from each group requiring dialysis. Although increases in the serum creatinine level occurred postoperatively in more patients who received aprotinin (20/108) than in those given placebo (13/108), the difference between the two groups was not statistically significant (p = 0.186), and the increases were generally small and transient. Likewise, there was no difference between the groups in terms of the incidence of abnormal serum electrolyte levels, blood urea nitrogen levels, or urinalysis findings, or in the frequency of abnormal creatinine clearance rates. Under the conditions described, aprotinin use does not appear to be associated with a significant risk of serious renal toxicity.

Aprotinin↗

PubMed1995

Serial changes in left and right ventricular systolic and diastolic dynamics during the first year after an index left ventricular Q wave myocardial infarction.

OBJECTIVES: This study quantified serially biventricular emptying and filling after infarction and related these to changes in volume, muscle mass, wall stress and contractility. BACKGROUND: There are limited data on serial changes in ventricular dynamics after infarction. METHODS: Forty patients had serial electron beam computed tomographic examinations during the first year after index Q wave infarction (21 anterior, 19 inferior), and global biventricular volumes, peak rates of emptying and filling and left ventricular muscle masses were quantified. Mean mid-left ventricular end-systolic wall stresses, rate-corrected velocities of circumferential shortening and two indexes of left ventricular contractility--the end-systolic wall stress/volume ratio and the end-systolic wall stress/rate-corrected velocity of circumferential shortening relation--were estimated in each instance. RESULTS: Patients with anterior infarction had an increase in biventricular chamber volume of 15% to 35% by 1 year. Global biventricular peak rates of emptying and filling were decreased by 20% to 30% from hospital discharge to 6 weeks but thereafter remained unchanged. Despite a significant increase in mean wall stresses, the end-systolic wall stress/volume ratio remained unchanged during the year. The rate-corrected velocities of circumferential shortening declined serially after anterior infarction but did so in proportion to the increase in mean wall stresses, consistent with no net change in left ventricular contractility. Patients with inferior infarction showed a trend toward similar changes, but the magnitudes did not reach significance. CONCLUSIONS: Left (and right) ventricular global peak rates of emptying and filling during the first year after infarction can be altered in the absence of additional ischemic injury but are more consistent with responses to changes in left ventricular afterload than changes in intrinsic ventricular performance or contractility. Serial changes in left ventricular afterload after infarction are largely due to progressive chamber enlargement and limited development of compensatory hypertrophy during the first year. Intrinsic global left ventricular contractile performance was not altered by postinfarction cardiac remodeling in the patients examined.

Coronary Circulation↗

PubMed1995

Serial changes in regional right ventricular free wall and left ventricular septal wall lengths during the first 4 to 5 years after index anterior wall myocardial infarction.

OBJECTIVES: This study investigated serial changes in regional right ventricular free wall and interventricular septal wall lengths during the first 4 to 5 years after an index anterior wall myocardial infarction. BACKGROUND: We previously demonstrated that remodeling after anterior wall myocardial infarction was a biventricular process; however, regional changes in biventricular topology were not investigated. METHODS: Serial electron beam computed tomographic scanning was performed in 19 patients at five times (hospital discharge and at 6 weeks, 6 months, 1 year and 4 to 5 years) after an index anterior wall myocardial infarction, and global and regional right ventricular free wall and interventricular septal wall lengths were quantified. RESULTS: At a mean (+/- SD) of 1,642 +/- 171 days (4 to 5 years) after infarction, global end-diastolic and end-systolic right ventricular free wall and interventricular septal wall lengths increased in parallel by 13% to 23% as global left and right ventricular volumes increased 22% to 29% from hospital discharge to 4 to 5 years after infarction. When global right ventricular free wall was compared with interventricular septal wall lengths, percent increases at end-diastole and end-systole were not statistically different at any time during the study period. Distinct regional changes in both right ventricular free wall and interventricular septal wall lengths after infarction were most dramatic during the first 6 weeks and primarily confined to the most apical levels. However, further and significant increases in both were observed by 4 to 5 years after infarction. CONCLUSIONS: Changes in both right ventricular free wall and interventricular septal wall lengths were apparent during the 4 to 5 years after the index anterior wall infarction, and the combination of both contributed to global increases in right and left ventricular chamber volumes. Regional changes in both right ventricular free wall and interventricular septal wall lengths were almost exclusively confined to their respective apices and progressed generally in parallel; however, the cause-and-effect relation remains speculative at the present time.

Adult↗

PubMed1994

Relation of coronary calcium determined by electron beam computed tomography and lumen narrowing determined by autopsy.

Coronary calcium determined by electron beam computed tomography (CT) has not been systematically evaluated regarding prediction of histopathologic atherosclerotic disease. Furthermore, gender specificity has not been examined. The 3 major epicardial arteries were dissected from 13 consecutive hearts (5 women and 8 men) after autopsy. Each artery was straightened and scanned using CT in contiguous 3 mm thick cross sections. After imaging, histologic sections were prepared at corresponding intervals and luminal area obstruction determined by planimetry. Electron beam CT scans were analyzed to determine coronary calcium area (i.e., tomographic area with CT density > 130 Hounsfield units). A total of 522 histologic specimens were examined and paired with corresponding CT scans (182 in women, 340 in men). Receiver-operating characteristic (ROC) analysis was used to define site specificity of calcium area for luminal area narrowing by atherosclerosis. ROC curve areas for segmental CT calcium and prediction of atherosclerosis representing mild, moderate, or severe disease were, respectively, 0.712, 0.843, and 0.857 for women and 0.732, 0.793, and 0.841 for men. Curves relating false-positive rate (1-specificity) to predefined degrees of atherosclerotic narrowing versus calcium area were curvilinear. In both women and men, calcium areas on the order of 1 mm2/coronary segment were necessary to predict at least mild atherosclerosis with a false-positive rate of 0% (i.e., 100% specificity), whereas a calcium area > 3 mm2 was necessary to predict the same result for severe disease. In conclusion, coronary artery calcium area as determined by electron beam CT has the potential to predict segmental histopathologic coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1994

Ventricular dilatation and remodeling after myocardial infarction.

OBJECTIVE: To discuss the important predictors of ventricular enlargement after myocardial infarction and the appropriate time frame for the initiation of medical and pharmacologic therapy. DESIGN: A review of the important contributions relative to the process known as "postinfarction ventricular remodeling" is provided; current clinical implications and areas for future investigation are discussed. MATERIAL AND METHODS: Ventricular dilatation is an important factor in the prognosis after infarction. Stretching and thinning of the myocardium within the infarct region can be seen within hours after the acute event and may be accompanied by delayed but potentially progressive stretching and thinning in the noninfarct regions. Development of left ventricular hypertrophy in the nonischemic myocardium, in response to increased wall stress, can be observed but may be insufficient for proper compensation. This process is referred to as postinfarction remodeling and can result in progressive and long-term changes in ventricular architecture and function in the absence of additional ischemic injury. RESULTS: The most effective way to limit the extent of postinfarction ventricular remodeling is to limit infarct size by prompt medical intervention within the first few hours. In addition to traditional post-infarction medications such as beta-blockers, nitrates, and aspirin, long-term benefit may be derived by use of adjunctive pharmacologic therapy such as angiotensin converting enzyme inhibitors, which have been shown to be valuable in limiting the extent of ventricular chamber dilatation after infarction. Studies in animal models and conclusions from clinical trials have shown that angiotensin converting enzyme inhibitors also decrease late mortality and cardiac morbidity after infarction, likely through favorable effects on both hemodynamic and neurohumoral factors specific to this class of medication. CONCLUSION: These investigations notwithstanding, further studies are necessary for a complete understanding of the pathogenesis of postinfarction ventricular remodeling and the appropriate timing of specific pharmacologic therapy intended to limit ventricular dilatation. The hemodynamic and neurohumoral interactions on and within the heart must be thoroughly understood relative to microscopic and macroscopic changes in cardiac size, shape, and function after myocardial infarction.

Animals↗

PubMed1994

Quantification of global and regional renal blood flow with electron beam computed tomography.

Alterations in renal blood flow distribution may occur in a variety of pathophysiologic situations; however, quantification of global and regional renal blood flows has been limited because of the lack of reliable, noninvasive techniques. To determine the feasibility of flow measurements with electron-beam computed tomography (EBCT), six anesthetized dogs were scanned by EBCT during basal conditions, after renal vasodilation, and at recovery. Flow (mL/min/cm3 tissue) was calculated from EBCT-derived time-density curves using three different algorithms and compared with simultaneously obtained electromagnetic flow (EMF) probe measurements after indexing to EBCT-derived renal volume. EBCT-determined flow correlated well with EMF measurements regardless of the algorithm used. An algorithm using the area under the time-density curve was concluded to be the most suitable for calculation of renal blood flow; it correlated with EMF as EBCT flow = 44.5 + 1.05 EMF (r = 0.885, SEE = 31.2 mL/min, P < .0001). Consistent overestimation of flow by EBCT resulted probably from retention of contrast media in the renal parenchyma. EMF showed an increase of 20 +/- 10% in renal blood flow after vasodilation. EBCT-derived global, cortical, and medullary flows increased by 33.8 +/- 10.3%, 24.8 +/- 17.8%, and 99.0 +/- 73.8%, respectively. In conclusion, EBCT was found feasible for credible quantitation of renal blood flow in the physiologic range studied.

Algorithms↗

PubMed1994

A method for automatic edge detection and volume computation of the left ventricle from ultrafast computed tomographic images.

RATIONALE AND OBJECTIVES: Detection of endocardial and epicardial borders of the left ventricle (LV) using various imaging modalities is time-consuming and prone to interpretive error. An automatic border detection algorithm is presented that is used with ultrafast computed tomographic images of the heart to compute cavity volumes. METHODS: The basal-level slice is identified, and the algorithm automatically detects the endocardial and epicardial borders of images from the basal to the apical levels. From these, the ventricular areas and chamber volumes are computed. The algorithm uses the Fuzzy Hough Transform, region-growing schemes, and optimal border-detection techniques. The cross-sectional areas and the chamber volumes computed with this technique were compared with those from manually traced images using canine hearts in vitro (n = 8) and studies in clinical patients (n = 27). RESULTS: Though the correlation was good (r = .88), the algorithm overestimated the LV epicardial area by 4.8 +/- 6.4 cm2, though this error was not statistically different from zero (P > .05). There was no difference in endocardial areas (r = .95, P > .05). The algorithm tended to underestimate the end-diastolic volume (r = .94) and the end-systolic volume (r = .94), although these errors were not statistically different from zero (P > .05). The algorithm tended to underestimate the ejection fraction (r = .80), although this error was not statistically different from zero (P > .05). CONCLUSIONS: Automatic detection of myocardial borders provides the clinician with a useful tool for calculating chamber volumes and ejection fractions. The algorithm, with the corrections suggested, provides an accurate estimation of areas and volumes. This algorithm may be useful for contour border identification with ultrasound, positron-emission tomography, magnetic resonance imaging, and other imaging modalities in the heart, as well as other structures.

Algorithms↗

PubMed1994

Left ventricular volume and mass: Comparative study of two-dimensional echocardiography and ultrafast computed tomography.

This study was undertaken to define the accuracy of two-dimensional echocardiography in the determination of left ventricular end-diastolic and end-systolic volumes, stroke volume, ejection fraction, and mass when compared to ultrafast cine computed tomography in the same 56 patients. Single-plane and biplane modified Simpson's rule, single-plane and biplane ellipsoidal formula, bullet formula (biplane only), and biapical Simpson's rule methods were utilized. Linear regression analysis showed the strongest correlation with the modified biplane Simpson's rule (mean r = 0.897). In valvular heart disease (n = 12) and dilated cardiomyopathy (n = 6), the mean correlation coefficients for all methods were high (r = 0.894 and 0.911, respectively). The mean correlation coefficient for all methods in patients with prior myocardial infarction (n = 25) was relatively poor (r = 0.643). Intraobserver and interobserver variabilities for all methods were low (r = 0.980 and 0.965, respectively). It is concluded that calculations of left ventricular volumes and mass by two-dimensional echocardiography are accurate and reproducible in patients with a global effect on the left ventricle and were less acceptable in patients with segmental (ischemic) left ventricular involvement. The best measurement technique is a modified biplane Simpson's rule.

Adult↗

PubMed1994

Quantitative echocardiography: a comparison with ultrafast computed tomography in patients with chronic aortic regurgitation.

Chronic aortic regurgitation leads to progressive left ventricular dilatation and hypertrophy. It is important to be able to measure these variables for clinical decision making on the timing of aortic valve replacement. M-mode and two-dimensional echocardiography are widely utilized in clinical practice for a qualitative assessment of left ventricular size and function. Recent recommendations have been proposed for the use of quantitative assessment by left ventricular size and left ventricular mass by two-dimensional echocardiography; there has been no study examining the validity of these measurements in patients with aortic regurgitation. The purpose of this study was to prospectively examine the various geometric models of echocardiographically determined left ventricular mass and volumes in patients with chronic aortic regurgitation compared with cine-computed tomographic scanning. Twenty-two patients with chronic aortic regurgitation were prospectively identified and underwent two-dimensional echocardiographic and cine-computed tomographic scanning. M-mode and two-dimensional echocardiographic images were analyzed on an off-line measurement digital system. Seven previously described geometric models were used in this study for quantitative analysis. Both left ventricular mass and left ventricular volume were calculated from real-time ultrafast tomographic scans. Left ventricular mass determinations by two-dimensional echocardiography correlated more than M-mode determinations (r = 0.84 vs. r = 0.75, standard error of the estimate (SEE) = 38 g vs. 139 g). Biplane two-dimensional echocardiography formulas using Simpson's rule construct yielded more accurate values for left ventricular end-diastolic volumes (r = 0.92, SEE = 24 ml) than either the single-plane Simpson's rule (r = 0.58, SEE = 73 mL) or methods using predetermined models of left ventricular shape (r = 0.80, SEE = 38 ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Right ventricular dilatation and remodeling the first year after an initial transmural wall left ventricular myocardial infarction.

Left ventricular (LV) remodeling after LV myocardial infarction was described previously. Little is known regarding concomitant adaptation, if any, in right ventricular (RV) volumes after LV infarction. To examine this issue, cine-computed tomography was used to determine serial changes in absolute global LV and RV volumes in 27 patients without clinical heart failure during the first year after an initial Q-wave myocardial infarction (14 anterior and 13 inferior). The patient group with anterior wall LV infarction showed progressive increases in LV and RV volumes from hospital discharge to 1 year (end-diastolic volumes +25 and +13%, respectively; and end-systolic volumes +35 and +15%, respectively). In patients with inferior wall LV infarction, both LV end-diastolic and end-systolic volumes increased significantly during the study period (+13 and +15%, respectively). Despite a trend for RV end-diastolic volume to be increased at 1 year, neither end-diastolic nor end-systolic volume increased significantly after hospital discharge following inferior wall LV infarction. Absolute RV end-diastolic volume was not significantly different between the infarct groups at any time after infarction. In conclusion, global changes occur in both LV and RV volumes during the first year after an initial infarction regardless of infarct location. The magnitude of these changes was greater after anterior than inferior wall LV infarction.

Adult↗

PubMed1993

Nonparallel changes in global left ventricular chamber volume and muscle mass during the first year after transmural myocardial infarction in humans.

OBJECTIVES: This study was designed to serially assess time-dependent changes in both chamber volume and myocardial muscle mass after infarction in humans. BACKGROUND: Dilation of the left ventricular chamber has been previously described after transmural myocardial infarction. METHODS: Global left ventricular chamber volumes and muscle mass were quantified by using cine computed tomographic scanning in 18 patients at hospital discharge and 6 weeks, 6 months and 1 year after an initial transmural myocardial infarction (12 anterior and 6 inferior). No patient had heart failure during the initial hospital stay or on any subsequent follow-up visit. RESULTS: The patients with anterior myocardial infarction (estimated infarct extent 27 +/- 2% of left ventricle) demonstrated a progressive increase in left ventricular end-diastolic volume from 148 +/- 9 ml (mean +/- SEM) at hospital discharge to 180 +/- 9 ml at 1 year after infarction (p < 0.001). However, global left ventricular muscle mass decreased significantly during the 1st 6 weeks after infarction but returned by 1 year to nearly the value determined at hospital discharge (177 +/- 13 vs. 165 +/- 10 g, p = NS). The changes in global muscle mass did not parallel the steady and progressive increases in chamber end-diastolic volume. The end-diastolic chamber volume to muscle mass ratio, an index of global left ventricular wall tension, increased steadily after hospital discharge but remained level by 1 year after infarction. The time course of changes in global end-systolic chamber volume was roughly proportional to the concomitant changes in end-diastolic volume. During this same time period, left ventricular stroke volume remained constant or improved from that determined at baseline. Global left ventricular end-diastolic and end-systolic volumes remained relatively static during the 1st year in the patient subgroup with inferior wall myocardial infarction (estimated infarct extent 10 +/- 1% of left ventricle), but global muscle (myocardial) mass initially decreased and then increased in a pattern similar, although of smaller magnitude, to that observed in patients with anterior wall myocardial infarction. CONCLUSIONS: Overall, left ventricular end-diastolic and end-systolic chamber volumes increase progressively from hospital discharge to 1 year after an initial transmural myocardial infarction in patients with a moderately large anterior wall infarction but remain stable in patients with a small inferior wall infarction. Concurrently, total left ventricular muscle mass decreases significantly during the initial 6 weeks after infarction (presumed largely secondary to changes in the necrotic segments) but then returns to the hospital discharge baseline values by 1 year. These data are consistent with the late development of, at most, limited ventricular hypertrophy in the noninfarcted myocardium that occurs well after the early and progressive left ventricular chamber dilation observed in patients with a moderate to large myocardial infarction. These data, in particular as applied to patients with anterior infarction, suggest that ventricular wall tension is significantly elevated at least during the 1st year after an initial transmural myocardial infarction. These observations may explain the potential utility of agents aimed at reducing afterload or ventricular wall tension during the early convalescent phase after myocardial infarction.

Female↗

PubMed1993

X-ray computed tomography and magnetic resonance imaging of the cardiovascular system.

Both electron beam (or ultrafast) x-ray computed tomography and magnetic resonance imaging are developing cardiovascular imaging modalities that can provide high temporal and spatial resolution images of the beating heart and the great vessels in the outpatient setting. The three-dimensional registration of these images has facilitated numerous studies, showing that these devices are capable of quantitating cardiovascular anatomy, function, and blood flow. Continued research employing these methodologies has examined both applications that are complementary to more traditional noninvasive cardiology tools, such as two-dimensional echocardiography and radionuclide and perfusion imaging, as well as applications unique to computed tomography or magnetic resonance imaging. This review discusses progress made in x-ray computed tomography, focusing on the application of electron beam computed tomography and new applications of magnetic resonance imaging within the past 2 years. Specific comments are made regarding these applications, as well as the limitations of both with regard to general clinical applications.

Blood Flow Velocity↗

PubMed1993

Right ventricular assessment in patients presenting for lung transplantation.

Chronic pulmonary disease is associated with varying degrees of cardiac dysfunction. Because of the potentially predominant effect of severe lung disease on right ventricular (RV) size and function, a reliable method to assess RV mechanics before and after lung transplantation may provide information of long-term significance and/or prognosis. Conventional invasive and non-invasive imaging methods have a number of limitations in evaluating RV function. Ultrafast computed tomographic (ultrafast CT) scanning has been shown to provide quantitative assessment of RV and left ventricular (LV) function in individuals with and without cardiac disease. Twenty-two patients presenting during evaluation for possible lung transplantation with end-stage pulmonary disease formed the basis of this study. There were 14 patients with chronic obstructive pulmonary disease and 8 with pulmonary fibrosis. Conventional transthoracic echocardiography and ultrafast CT were used for the assessment of RV and LV function. All patients had invasive assessment of right-sided hemodynamics and pulmonary function studies performed within 7-10 days of cardiac imaging. A qualitative assessment of RV size or function was possible in all but two patients by echocardiogram, but in 45%, the echocardiographic examination was described as suboptimal. In contrast, a quantitative assessment of ventricular volumes and systolic function was obtained in all patients by ultrafast CT. Pulmonary function parameters or hemodynamic measurements obtained during cardiac catheterization did not correlate with any assessment of RV function. We concluded that (1) ultrafast CT provides measurement of the RV and LV cavity dimension and systolic function; (2) invasive right-sided hemodynamics or pulmonary function studies do not predict RV function; and (3) echocardiography does not uniformly provide assessment of RV function in patients with chronic pulmonary disease.

Adult↗

PubMed1992

Noninvasive definition of anatomic coronary artery disease by ultrafast computed tomographic scanning: a quantitative pathologic comparison study.

OBJECTIVES: The aim of this study was to determine the relation between coronary artery calcification detected by ultrafast computed tomographic scanning and histopathologic coronary artery disease. BACKGROUND: Recent studies suggest that discrete coronary artery calcification as visualized by ultrafast computed tomographic scanning may facilitate the noninvasive detection or estimation, or both, of the in situ extent of coronary disease. Such quantitative relations have not been established. METHODS: Thirteen consecutive perfusion-fixed autopsy hearts (from eight male and five female patients aged 17 to 83 years) were scanned by ultrafast computed tomographic scanning in contiguous 3-mm tomographic sections. The major epicardial arteries were dissected free, positioned longitudinally and scanned again in cross section. Coronary artery calcification in a coronary segment was defined as the presence of one or more voxels with a computed tomographic density > 130 Hounsfield units. Each epicardial artery was sectioned longitudinally, stained and measured with a planimeter for quantification of cross-sectional and atherosclerotic plaque areas at 3-mm intervals, corresponding to the computed tomographic scans. A total of 522 paired coronary computed tomographic and histologic sections were studied. RESULTS: Direct relations were found between ultrafast computed tomographic scanning coronary artery calcium burden and atherosclerotic plaque area and percent lumen area stenosis. However, the range for plaque area or percent lumen stenosis, or both, associated with a given calcium burden was broad. Three hundred thirty-one coronary segments showed no calcification by computed tomography. Although atherosclerotic disease was found in several corresponding pathologic specimens, > 97% of these noncalcified segments were associated with nonobstructive disease (< 75% area stenosis); if no calcification was determined in an entire coronary vessel, all corresponding coronary disease was found to be nonobstructive. To determine the relation between arterial calcification and any atheromatous disease, computed tomographic calcium burden for each segment was paired with the histologic absence or presence of disease. Ultrafast computed tomographic scanning had a sensitivity and specificity of 59% and 90% and a negative and positive predictive value of 65% and 87%, respectively. A direct correlation was found (r = 0.99) between total calcium burden calculated from tomographic scans of the heart as a whole and scans of the arteries obtained in cross section. CONCLUSIONS: The detection of coronary calcification by ultrafast computed tomographic scanning is highly predictive of the presence of histopathologic coronary disease, but the use of this technique to define the extent of coronary disease may be limited. However, the absence of coronary calcification at any site is highly specific for the absence of obstructive disease.

Adolescent↗