[Current status of coronary diagnosis by magnetic resonance tomography].
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Coronary Disease↗
Biomedical subjects
W J Manning
Publications and source records attributed to W J Manning.
A preliminary report comparing magnetic resonance coronary angiography with conventional angiography.
BACKGROUND: The ability to assess the patency of coronary arteries by noninvasive means would represent an important advance. We have developed a magnetic resonance imaging (MRI) coronary angiographic technique that permits the display of areas of abnormal coronary blood flow. We have compared this method with conventional contrast angiography for the identification of coronary-artery stenoses. METHODS: MRI coronary angiography was performed with an electrocardiographically gated sequence in 39 subjects, 33 to 84 years of age, who were scheduled for elective cardiac catheterization with coronary angiography. Sequential overlapping transverse and oblique sections were acquired during periods of breath-holding and were displayed as cine loops for analysis. MRI and conventional angiographic data were compared in a blinded manner. The four major epicardial coronary arteries were classified by MRI coronary angiography as being normal (or having only minimal irregularities) or as having disease that was moderately severe to severe. RESULTS: The sensitivity and specificity of MRI coronary angiography, as compared with conventional angiography, for correctly identifying individual vessels with > or = 50 percent angiographic stenoses were 90 percent and 92 percent, respectively. The corresponding positive and negative predictive values were 0.85 and 0.95, respectively. The sensitivity and specificity of the technique were 100 percent and 100 percent, respectively, for the left main coronary artery, 87 percent and 92 percent for the left anterior descending coronary artery, 71 percent and 90 percent for the left circumflex coronary artery, and 100 percent and 78 percent for the right coronary artery. CONCLUSIONS: MRI coronary angiography provides a new approach to evaluating the patency of coronary arteries. These preliminary data suggest that this technique may provide a noninvasive means of evaluating patients with known or suspected coronary artery disease. At its current stage of development, this procedure may be most helpful for excluding clinically important stenoses in patients referred for diagnostic contrast angiography.
Adult↗
Cardioversion from atrial fibrillation without prolonged anticoagulation with use of transesophageal echocardiography to exclude the presence of atrial thrombi.
BACKGROUND: Because atrial thrombi are poorly detected by conventional noninvasive techniques such as transthoracic echocardiography, patients with prolonged atrial fibrillation usually receive several weeks of oral anticoagulation therapy before cardioversion is attempted. We wondered whether transesophageal echocardiography, an accurate method of detecting atrial thrombi, would allow early cardioversion to be performed safely if no thrombi were identified. METHODS: A total of 669 consecutive patients admitted with the diagnosis of atrial fibrillation were screened. Patients were excluded if they were receiving long-term anticoagulation, if the duration of atrial fibrillation was two days or less, if they were not candidates for cardioversion, or if transesophageal echocardiography was contraindicated. Of 119 qualifying patients, 94 agreed to participate; the average duration of atrial fibrillation was 4.5 weeks. Participating patients underwent transthoracic echocardiography and transesophageal echocardiography followed by cardioversion if no thrombi were seen. Short-term anticoagulation with heparin was used in 80 patients before cardioversion, and 60 patients received warfarin for one month after cardioversion. RESULTS: Fourteen atrial thrombi were identified in 12 patients (13 percent), and 12 of the 14 thrombi were visualized only on transesophageal echocardiography. Cardioversion was deferred in all 12 patients. Two of these 12 patients died suddenly; 4 of the 10 surviving patients underwent uneventful cardioversion after prolonged oral anticoagulation. Seventy-eight of the 82 patients without thrombi underwent successful cardioversion to sinus rhythm (47 by means of antiarrhythmic drugs and 31 by electrical cardioversion), all without long-term oral anticoagulation. None of these patients (95 percent confidence interval, 0 to 4.6 percent) had an embolic event. CONCLUSIONS: In patients with atrial fibrillation of unknown or prolonged duration who are not receiving long-term anticoagulation, atrial thrombi are detected by transesophageal echocardiography in only a small minority (13 percent in our study). Our preliminary data suggest that if transesophageal echocardiography excludes the presence of thrombi, early cardioversion can be performed safely without the need for prolonged oral anticoagulation before the procedure.
Adult↗
Vitamin K and maintenance of skeletal integrity in adults.
PURPOSE: To determine the role of vitamin K status in the maintenance of skeletal integrity in adults. PATIENTS AND METHODS: 1. Bone mineral density (BMD) was measured by quantitative digital radiography (QDR) in 50 patients taking a vitamin K antagonist (warfarin) who were recruited from a large urban cardiology practice, and 50 age-, sex- and race-matched controls recruited from the community. 2. The relationship of BMD versus indices of vitamin K status (determined by measuring levels of vitamin K and descarboxyprothrombin in the plasma) in 113 nonanticoagulated adults was assessed. RESULTS: Measurements of BMD in the hip and spine were similar in anticoagulated subjects and matched controls. Multivariate analysis revealed that use of warfarin was not associated with a lower BMD. Ninety-five percent confidence intervals excluded a 0.06 g/cm2 reduction in BMD associated with the use of warfarin. Indices of vitamin K status did not correlate with BMD in normal subjects. CONCLUSIONS: Patients receiving long-term maintenance therapy with a vitamin K antagonist have normal bone density. BMD is unrelated to vitamin K status in nonanticoagulated subjects. These data suggest that vitamin K does not have a major role in maintenance of skeletal integrity in adults.
Adult↗
Detecting ozone and demonstrating its phytotoxicity in forested areas of Poland: a pilot study.
Ambient concentrations of ozone (O(3)) were measured and O(3) phytotoxicity to tobacco (Nicotiana tabacum L.) was demonstrated in several forest locations in Poland during a pilot study from July-October, 1991. At southern and central locations in Poland, the 24-hour average O(3) concentrations measured with a UV absorption photometer were in the range of 32-55 ppb, and the corresponding 1-hour maxima in the range of 39-83 ppb. At these locations longer period (four to fifteen days) average concentrations were determined using O(3) passive samplers (DGA, Inc.) and were reaching 60 ppb, while at Bialowieza in eastern Poland O(3) concentrations averaged less than 40 ppb. In Szarow, near the Niepolomice Forest in southern Poland, 1-hour O(3) maxima estimated from the data obtained using passive samplers were about 105 ppb in early September. At several locations in southern and central Poland, extensive O(3) injury was determined on O(3)-sensitive Bel W-3 tobacco plants; such injury did not occur in the Bialowieza Forest of eastern Poland. The results of this pilot study indicate that O(3) is present at phytotoxic levels in southern and central Poland.
Journal Article↗
Use of tobacco cultivars as biological indicators of ambient ozone pollution: an analysis of exposure-response relationships.
A summary is presented of the numerical analysis of the results from a study of exposure in an open-top chamber conducted at two locations in the north-east USA, utilizing tobacco (Nicotiana tabacum L.) cv. Bel-W3 (sensitive) and cv. Bel-B (tolerant) as differential indicators of ambient O(3) pollution. At both study sites, Bel-W3 was significantly more sensitive than Bel-B. There were differences in the weekly O(3) exposure dynamics and the consequent foliar injury scores on Bel-W3 between the two study sites. During the individual weekly exposures, the bottommost fully expanded leaf (leaf no. 1) on Bel-W3 was more sensitive than the second fully expanded leaf (leaf no. 2). There were no statistically significant differences in the injury scores on Bel-W3 leaf no. 1 between the non-filtered air open-top chamber and the chamberless, ambient field plot treatments at both study sites. In Mallow's critical-point best regression, among the many O(3) descriptors tested, number of hours during each week with O(3) concentrations > 40 ppb (N40) and > 60 ppb (N60) or the corresponding sums of their concentrations (SUM40 and SUM60) proved to be the best predictors of foliar injury on Bel-W3, leaf no. 1. The regression used N40 and N60 or SUM40 and SUM60 together and did not identify each variable alone or by itself as being important. Independent of this, all the R(2) values could account for only about 30-32% of the variability of the foliar injury responses, although these values were statistically significant. Covariance time-series analysis between weekly O(3) concentrations > 40 ppb and the corresponding foliar injury scores on Bel-W3 leaf no. 1 showed that foliar injury was in best spectral coherence with the O(3) exposure (> 40 ppb) during periods of moderate periodicity (variance). The overall results suggest that the visible foliar responses of tobacco Bel-W3 can be used as a qualitative, but not necessarily as a quantitative indicator of relative ambient O(3) pollution on a generalized temporal or spatial scale.
Journal Article↗
Dose-response studies with ethylenediurea (EDU) and radish.
There is some concern that the antiozonant ethylenediurea (EDU), used for crop loss assessment due to ambient ozone (O3) may per se affect plant growth and yield. In view of this, and to provide knowledge for later field experiments, dose-response studies with EDU and O3 were carried out in greenhouses in winter and spring 1989, using radish (Raphanus sativus L.) cv. 'Cherry Belle' and 'Red Prince', grown in two different substrates. EDU was applied as a single or repeated soil drench in concentrations ranging from 300 to 800 mg litre(-1) in the first, and from 100 to 400 mg litre(-1) in the second trial. In the second experiment, plants were exposed to a chronic level of O3, mimicking ambient patterns, or to filtered air after the EDU-treatment. When applied in concentrations above 300 mg litre(-1), EDU reduced growth, thereby affecting the development of the thickened hypocotyl far more than the shoot growth that was partially stimulated by lower doses of EDU. Phytotoxic symptoms on the leaves, attributable to EDU, were observed at concentrations above 200 mg litre(-1), but complete protection from visible O3-injury was provided by a single application of EDU at a concentration as low as 100 mg litre(-1). Significant interactions on growth characters measured between O3-exposure and EDU application were observed only in one of the substrates. While these results demonstrate the need for careful dose-response studies prior to field assessments, they also provide evidence of a dosage that is effective in protecting radish from O3 damage without interfering with plant growth itself.
Journal Article↗
Radish (Raphanus sativus L.): a model for studying plant responses to air pollutants and other environmental stresses.
The use of Raphanus sativus L. as a model crop for studies on plant response to environmental stresses is reviewed with emphasis on the effects of different atmospheric pollutants (O(3), SO(2), NO(2), acidic precipitation) and their combinations. Responses to temperature, light supply, water stress, and atmospheric CO(2) are also studied and discussed. In addition, the references reviewed are evaluated in terms of their experimental protocols on growth conditions and recommendations for optimal ranges of environmental and cultural variables, i.e. light, temperature, nutrient supply are given. Its distinct pattern of biomass partitioning, the small dimensions along with short and easy culture make radish an excellent experimental plant. The fleshy below-ground storage organ, formed by the hypocotyl and upper radicle, acts as the major sink during vegetative development. Abundant assimilate supply due to elevated levels of CO(2) along with high irradiation frequently promote hypocotyl growth more than shoot growth, whereas under conditions of stress shoot growth is maintained at the expense of the hypocotyl. This makes the hypocotyl: shoot ratio of radish a very sensitive and suitable indicator for various environmental stresses. Potential weaknesses and shortcomings of radish in its role as a model crop, particularly the high variability of injury and growth responses, are discussed along with possible solutions. Future research needs are derived from the summarized results presented and from some disparities among findings within the literature reviewed.
Journal Article↗
Dynamics of biomass partitioning in field-grown radish varieties, treated with ethylenediurea.
During the growing season of 1990, five staggered crops of radish (Raphanus sativus L.) were grown in the field, using the cultivars 'Cherry Belle', 'Red Prince', and 'Red Devil B'. Half of the plants received a soil drench (100 ml plant(-1); 100 mg litre(-1) of ethylenediurea (EDU) once, early in plant development. Destructive harvests were carried out at 2-day intervals during vegetative development. Non-linear growth kinetics, derived from Richards' function, were fitted to the dry weight data of the total plant, main organs (shoot and hypocotyl) and to the dry weight ratio between below-ground and above-ground organs. Estimating the parameters of these non-linear functions and testing their differences between EDU-treated and untreated plants unveiled biologically meaningful information on the impact of different levels of ambient ozone (O(3)) during the growth periods. The modified function which was applied to the data of biomass partitioning between the major plant parts was more powerful in detecting transient alterations in assimilate allocation compared to the growth dynamics of individual plant organs. At low levels of O(3), biomass partitioning towards the below-ground sink organs was slightly delayed and finally restricted in EDU-treated plants. When ambient O(3) reached moderate levels, which did not cause visible foliar injury, assimilate partitioning between organs was only insignificantly altered during early growth when EDU-treatments were compared. As growth progressed, however, less assimilates were allocated towards the hypocotyl and roots in the plants not protected by EDU. This pattern was similar in all cultivars tested, but was smallest in 'Cherry Belle', which is known to be sensitive to O(3) with respect to foliar injury. During the 15- to 19-day periods of rapid growth, the O(3)-exposure >80 nl litre(-1) ranged from 0.015 to 0.209 microl litre(-1) O(3) h, which corresponds to 7 h d(-1) mean values between 40 and 50 nl litre(-1) O(3), confirming that ambient ozone did not exceed a moderate level in this study.
Journal Article↗
Dose-response studies with the antiozonant ethylenediurea (EDU), applied as a soil drench to two growth substrates, on greenhouse-grown varieties of Phaseolus vulgaris L.
To study plant growth and yield effects of the antiozonant ethylenediurea (EDU), which is frequently used for ozone crop loss assessments, dose-response studies were carried out with potted bean plants under greenhouse conditions in winter and spring. Two cultivars of Phaseolus vulgaris L., differing in sensitivity to ozone (O(3)), were grown in unfiltered air on a sandy loam rich in organic matter and on a vermiculite-clay mixture. Four treatments of EDU at concentrations from 300 to 800 mg liter(-1) were given as a soil drench during plant development. Foliar symptoms of EDU phytoxicity were observed at all doses, and plant biomass, particularly pod dry weight, was considerably reduced to increasing doses of EDU. Primary and first trifoliate leaf weight in EDU-treated plants increased as did the number of buds, indicating an extension of vegetative growth and a delay of reproductive processes. 'BBL 290' beans, which are O(3)-sensitive, were injured by EDU more than the O(3)-tolerant 'BBL 274'. The phytotoxic effects of EDU were more pronounced in the synthetic growth substrate than in field soil. In a second experiment, EDU was applied in concentrations from 100 to 400 mg liter(-1) to 'BBL 290' plants, exposed to filtered air or simulated levels of O(3) pollution. In field soil, plant growth and biomass partitioning in filtered air was only slightly altered by EDU, although leaf injury due to EDU occurred. In the vermiculite-clay mix, the biomass of most plant organs, particularly that of roots, was linearly reduced with increasing EDU doses. O(3) did not cause any alteration in plant biomass in field soil-grown and EDU-treated plants. Ozone leaf injury, which affected 67% of primary leaf area in non-treated plants, was completely suppressed by EDU doses as low as 100 mg liter(-1). This indicates that low concentrations of EDU, which do not affect plant growth in field soil, provide sufficient protection from O(3) injury. The need for careful EDU dose-response studies prior to field assessments is emphasized.
Journal Article↗
Atrial ejection force: a noninvasive assessment of atrial systolic function.
OBJECTIVES: The purpose of this study was to define atrial ejection force and to develop a method for its noninvasive measurement from echocardiographic data. BACKGROUND: Assessment of diastolic function through measurement of the components of ventricular filling has largely neglected the vigor of atrial systole, in part because this has been difficult to quantify. However, atrial ejection force, defined as that force exerted by the left atrium to accelerate blood into the left ventricle during atrial systole, can be assessed noninvasively by combined two-dimensional imaging and Doppler echocardiography. This index of atrial function, based on classic newtonian mechanics, provides a physiologic assessment of atrial systolic function. METHODS: To evaluate the usefulness of atrial ejection force, we studied the return of left atrial ejection force in 29 patients after elective cardioversion for atrial fibrillation. Transmitral Doppler inflow patterns at rest were assessed immediately after cardioversion and at 24 h, 1 week, 1 month and > 3 months later. A healthy adult group (n = 10) served as control subjects. RESULTS: After successful cardioversion, atrial ejection force was significantly depressed compared with that in the control group (5.2 +/- 6.8 vs. 16.3 +/- 4.7 kdynes; p < 0.0001). Over successive weeks, atrial ejection force improved in the subgroup of patients who remained in sinus rhythm (n = 18), whereas no improvement was seen during the period of maintained sinus rhythm in the patients with subsequent reversion to atrial fibrillation (n = 11). CONCLUSIONS: Atrial ejection force provides a physiologic assessment of atrial systolic function and is a potentially useful index for assessing atrial contribution to diastolic performance. In patients who successfully underwent cardioversion from atrial fibrillation, atrial ejection force improved over several weeks only in the subgroup in which sinus rhythm was maintained.
Adult↗
Human coronary arteries: projection angiograms reconstructed from breath-hold two-dimensional MR images.
The authors sought to render projection magnetic resonance (MR) angiograms depicting a substantial length of human coronary arteries from sequential breath-hold two-dimensional MR images. Tomographic images of the right and left anterior descending coronary arteries were collected with use of a segmented gradient-recalled sequence that incorporated fat suppression and prone positioning of the patient over a surface coil. After editing the images to eliminate overlapping chamber signals and after realigning the images, a maximum-intensity-projection algorithm was applied to create projection angiograms. For the 10 coronary arteries without severe narrowing, visualized length with projection MR angiography was 109 mm +/- 29 (mean +/- standard error of estimate) versus 121 mm +/- 29 with conventional coronary angiography (ranges, 62-147 mm and 70-180 mm, respectively). At conventional angiography linear regression indicated vessel length to be 1.03 times the length depicted at MR angiography with good correlation (r = .8). Results indicate good correlation between measurements of vessel length with both conventional and MR angiography.
Adult↗
Fat-suppressed breath-hold magnetic resonance coronary angiography.
BACKGROUND: The ability to image the coronary arteries noninvasively would represent an advance in patient care. We have developed a magnetic resonance (MR) angiographic technique that allows the acquisition of complete images of coronary flow within a single breath-hold. By this method, the feasibility of noninvasive MR coronary angiography was evaluated in 25 subjects, including 19 healthy adult volunteers and six patients after diagnostic coronary angiography. METHODS AND RESULTS: Noninvasive MR coronary angiography was performed with a fat-suppressed ECG-gated gradient-echo sequence with k-space segmentation. Overlapping transverse sections were initially used to image coronary flow, with oblique images obtained after identification of proximal anatomy. The left main coronary artery was seen in 24 subjects (96%), with a mean diameter of 4.8 mm (range, 3.4-6.2 mm) and average length of 10 mm (range, 8-14 mm). The left anterior descending coronary artery was seen in 100% of subjects, with a mean proximal diameter of 3.6 mm (range, 2.6-4.3 mm) and for an average length of 44 mm (range, 28-93 mm). The left circumflex coronary artery was seen in 76% of subjects, with a mean proximal diameter of 3.5 mm (range, 2.6-4.3 mm) and for an average length of 25 mm (range, 9-42 mm). The right coronary artery was also identified in 100% of subjects, with a mean proximal diameter of 3.7 mm (range, 2.7-5.1 mm) and for an average length of 58 mm (range, 24-122 mm). Quantitative angiography of normal proximal segments demonstrated a good correlation with MR-determined lumen diameters (r = 0.86, p < 0.002). Occluded vessels in patients with coronary artery disease displayed an absence of flow signal distal to the occlusion, whereas vessels with significant angiographic stenoses demonstrated signal loss corresponding to the area of the stenosis, with visualization of the more distal vessel. CONCLUSIONS: Breath-hold MR coronary angiography provides visualization of the major epicardial vessels. In the future, MR coronary angiography may provide a noninvasive means for the evaluation of patients with known or suspected coronary artery disease.
Adult↗
Magnetic resonance angiography and flow quantification of coronary arteries.
Although further work is needed to improve spatial resolution and flow contrast as well as to lessen dependence on a regular cardiac rhythm, the potential clinical utility of MR coronary angiography is substantial. For the first time, information regarding coronary artery anatomy can be acquired in a completely noninvasive manner.
Arteries↗
Echocardiographically detected myocardial infarction in the mouse.
The ability to obtain high-quality echocardiographic images of the heart in a small mammal such as the mouse would enable investigators to noninvasively and serially assess cardiac function and identify focal lesions. We recently had the opportunity to perform noninvasive high-frequency M-mode echocardiography in a mouse that had a focal area of left ventricular hypokinesis involving the ventral wall. Postmortem histologic examination revealed lateral and ventrolateral wall infarction with fibrotic replacement of the ventricular wall and reactive hypertrophy of surrounding myocytes in noninfarcted zones. To our knowledge, this is the first reported case of noninvasive echocardiography identification of a myocardial infarction in the mouse and further high-lights the potential utility of this technique.
Animals↗
Magnetic resonance coronary angiography.
Despite the availability of numerous noninvasive tests to identify those with inducible myocardial ischemia, 20% of conventional contrast angiograms demonstrate no significant coronary artery stenoses. Magnetic resonance (MR) imaging is ideally suited for evaluation of the heart, and has already been shown to be highly accurate for the depiction and assessment of cardiac chamber size, ventricular function, and valvular insufficiency. Using conventional spin-echo and gradient-echo techniques, investigators have previously been able to characterize coronary artery bypass grafts as "patent" or "occluded," but visualization of large segments of the native coronary vessels was unsuccessful due to artifacts related to cardiac and respiratory motion. Recently, several new "fast imaging" breath-hold techniques, including k-space segmentation and spiral imaging, have shown great promise for both visualizing the native coronary arteries, assessing vessel patency, and quantifying coronary blood flow. Echo planar MR coronary angiography also appears to be feasible. Further software and hardware improvements are needed, but MR may soon prove to be the premier cardiac imaging technique by providing a comprehensive cardiac evaluation for those with suspected coronary artery disease, including information previously unobtainable by any other noninvasive test.
Coronary Artery Bypass↗
Coronary arteriovenous fistula presenting as congestive heart failure.
Coronary arteriovenous fistulae are rare, but can be of hemodynamic significance. We report a circumflex-coronary sinus fistula in an elderly man which was associated with a loud continuous murmur and congestive heart failure. Noninvasive evaluation, including transesophageal echocardiography and magnetic resonance imaging, suggested the diagnosis. Angiographic diagnosis of concomitant atherosclerotic coronary disease may be difficult, and can require postoperative study.
Aged↗
POEMS syndrome with myocardial infarction: observations concerning pathogenesis and review of the literature.
A 27-year-old white man with no significant risk factors for coronary artery disease presented with a 9-month history of progressive impotence, gynecomastia, lower extremity paresthesias, and extensive myocardial infarction and subsequently developed ulcerative proctitis. A diagnosis of POEMS syndrome was made based on the clinical presentation; additional physical findings of papilledema, clubbing, and hyperpigmentation; and laboratory findings of an immunoglobulin G M component of the lambda subtype, elevated cerebrospinal fluid protein, and typical sclerotic bone lesions. Abnormal in vitro binding of the patient's serum immunoglobulin to testicular tissue was also seen. Cardiac catheterization showed evidence of diffuse coronary artery narrowing and left ventricular wall motion abnormalities. Diffuse coronary involvement and ulcerative proctitis have not been previously described in POEMS syndrome. It is hypothesized that an abnormal immunoglobin (or fragment) is responsible for both findings. Furthermore, the detection of antitesticular autoantibodies suggests the possibility of an interaction between the antibody and Leydig cells, leading to an alteration in the synthesis and release of sex steroids and thereby explaining the gonadal failure seen in this syndrome. Long-term glucocorticoid therapy for the past 5 years has resulted in marked subjective and objective improvement.
Adult↗