Theron W. Ovitt

MR imaging of arrhythmogenic right ventricular cardiomyopathy: Morphologic findings and interobserver reliability

Background: Magnetic resonance (MR) imaging is frequently used to diagnose arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). However, the reliability of various MR imaging features for diagnosing ARVC/D is unknown. The purpose of this study was to determine which morphologic MR imaging features have the greatest interobserver reliability for diagnosing ARVC/D. Methods: Forty-five sets of films of cardiac MR images were sent to 8 radiologists and 5 cardiologists with experience in this field. There were 7 cases of definite ARVC/D as defined by the Task Force criteria. Six cases were controls. The remaining 32 cases had MR imaging because of clinical suspicion of ARVC/D. Readers evaluated the images for the presence of (a) right ventricle (RV) enlargement, (b) RV abnormal morphology, (c) left ventricle enlargement, (d) presence of high T1 signal (fat) in the myocardium, and (e) location of high T1 signal (fat) on a Likert scale with formatted responses. Results: Readers indicated that the Task Force ARVC/D cases had significantly more (χ2 = 119.93, d.f. = 10, p < 0.0001) RV chamber size enlargement (58%) than either the suspected ARVC/D (12%) or no ARVC/D (14%) cases. When readers reported the RV chamber size as enlarged they were significantly more likely to report the case as ARVC/D present (χ2= 33.98, d.f. = 1, p < 0.0001). When readers reported the morphology as abnormal they were more likely to diagnose the case as ARVC/D present (χ2 = 78.4, d.f. = 1, p < 0.0001), and the Task Force ARVC/D (47%) cases received significantly more abnormal reports than either suspected ARVC/D (20%) or non-ARVC/D (15%) cases. There was no significant difference between patient groups in the reported presence of high signal intensity (fat) in the RV (χ2 = 0.9, d.f. = 2, p > 0.05). Conclusions: Reviewers found that the size and shape of abnormalities in the RV are key MR imaging discriminates of ARVD. Subsequent protocol development and multicenter trials need to address these parameters. Essential steps in improving accuracy and reducing variability include a standardized acquisition protocol and standardized analysis with dynamic cine review of regional RV function and quantification of RV and left ventricle volumes.

Starting aspirin therapy after operation. Effects on early graft patency. Department of Veterans Affairs Cooperative Study Group.

BackgroundAlthough aspirin therapy started before operation improves vein graft patency after coronary artery bypass grafting, it also causes bleeding. The objective of this prospective, centrally directed, randomized, double-blind, placebo-controlled trial was to compare the effects of aspirin therapy started before operation with aspirin started 6 hours after operation on early (7–10-day) graft patency. Methods and ResultsPatients were randomized to receive either aspirin 325 mg or placebo the night before surgery; after operation, all patients received aspirin 325 mg daily, with the first dose administered through the nasogastric tube 6 hours after operation. Angiography was performed in 72% of the analyzed patients an average of 8 days after operation, and the primary end point was saphenous vein graft patency in 351 patients. Internal mammary artery graft patency was also assessed in 246 patients because many individuals received both internal mammary artery and vein grafts. In the patients given preoperative aspirin, the vein graft occlusion rate was 7.4 ± 1.3% compared with 7.8 ± 1.5% in those who received preoperative placebo (p =0.871). In the subgroup of patients receiving Y grafts, 0.0% of the grafts were occluded in the preoperative aspirin group compared with 7.0 ± 3.6% in the preoperative placebo group (p =0.066). The internal mammary artery occlusion rate was 0.0% (0 of 131) in the aspirin group compared with 2.4 ± 1.4% (three of 125) in the placebo group (p =0.081). Patients in the aspirin group received more transfusions than those in the placebo group (median, 900 versus 725 ml,p=0.006). The reoperation rate for bleeding in the aspirin group was 6.3% compared with 2.4% in the placebo group (p =0.036). Median chest tube drainage within the first 6 hours after operation was 500 ml in the aspirin group compared with 448 ml in the placebo group (p =0.011). Conclisions. Thus, preoperative aspirin is associated with increased bleeding complications and offers no additional benefit in early vein graft patency compared with starting aspirin therapy 6 hours after operation. There was a trend, although not significant, toward improved early patency for Y grafts and internal mammary artery grafts with preoperative aspirin.

Long-term graft patency (3 years) after coronary artery surgery. Effects of aspirin: results of a VA Cooperative study.

BACKGROUND The long-term success of coronary bypass surgery is dependent on graft patency after surgery. This trial was designed to determine if aspirin improved saphenous vein graft or internal mammary artery (IMA) graft patency between 1 and 3 years after coronary artery bypass grafting (CABG). METHODS AND RESULTS After receiving aspirin 325 mg/d for 1 year after CABG and undergoing a 1-year postoperative cardiac catheterization, patients were randomized to receive either aspirin (325 mg) or placebo for 2 additional years. Angiography was performed 3 years after surgery to determine the primary end point-saphenous vein graft patency in 288 patients and IMA graft patency in 167 patients. At 3 years after CABG, the saphenous vein graft occlusion rate was 17.0% (62 of 365) for patients treated with aspirin compared with 19.7% (74 of 376) for those who received placebo (P = .404). For saphenous vein grafts that were patent at 1 year, the occlusion rate at 3 years was 4.8% (15 of 313) for patients treated with aspirin compared with 4.2% (13 of 310) for patients who received placebo (P = .757). At 3 years, the IMA graft occlusion rate was 10.3% (8 of 78) for patients treated with aspirin compared with 7.9% (7 of 89) for patients who received placebo (P = .594). For IMA grafts that were patent at 1 year, the occlusion rate was 4.3% (3 of 70) for patients treated with aspirin compared with 2.5% (2 of 81) for patients who received placebo (P = .541). CONCLUSIONS These data suggest that aspirin treatment does not improve saphenous vein graft or IMA graft patency between 1 and 3 years after CABG.

Balloon dilation angioplasty for coarctation of the aorta.

Eleven patients with coarctation of the aorta (C of A) underwent balloon dilation angioplasty at the University of Arizona from November 1983 to January 1985. Eight had previously undergone surgery and 3 had native C of A. Two operations were considered unsuccessful: 1 in a patient who underwent tube graft--descending aortic anastomosis narrowing and 1 in a patient with a native wedge type of C of A. Overall mean gradient fell from 47 to 13 mm Hg immediately after the procedure. Mean gradient at repeat catheterization in 7 patients (mean 8 months after angioplasty) was 6 mm Hg. Five patients showed a transient increase in the gradient measured on the day after angioplasty, with 3 showing a fairly marked increase. Values returned to levels equal to or less than gradients measured immediately after the procedure. Angiographic findings at follow-up catheterization in 7 patients showed no evidence of aneurysm formation in either the operative group or in the 2 patients with native C of A who had a membrane type of deformity. Mean C of A to ascending aortic diameter ratios increased from 0.44 to 0.80. At repeat angiography, the mean ratio was 0.76 in the 7 patients studied. Further longitudinal studies in these patients are necessary before reaching conclusions about the advantage of this procedure over surgery, but these early longitudinal results are encouraging for the populations studied: postoperative patients and patients with native membrane types of C of A.

Predictors of Graft Patency 3 Years After Coronary Artery Bypass Graft Surgery

OBJECTIVES The purpose of this analysis was to define the factors that predict 3-year graft patency. BACKGROUND The success of coronary artery bypass graft surgery (CABG) is dependent on vein graft patency after the operation. It has been well established by a series of Department of Veterans Affairs Cooperative Trials that aspirin (325 mg daily) improves saphenous vein graft patency early (7 to 10 days) and at 1 year, but not at 3 years after CABG. This analysis, based on one of these trials, defined factors that predict 3-year graft patency. METHODS This analysis consisted of 266 patients, with 656 grafts that were patent 7 to 10 days after the operation, who underwent 3-year catheterization. To determine which patient-specific and/or graft-specific factors, or both, predict graft occlusion, a multivariate logistic regression analysis in terms of latent variables was used. It yielded a model that also took into account possible intraclass correlations. RESULTS For a vein graft that was patent at 7 to 10 days after the operation, the positive predictors, according to univariate analysis, for that graft being patent at 3 years were cross-clamp time < or = 80 min (p < 0.001), vein preservation solution temperature < or = 5 degrees C (p = 0.009), bypass time < or = 2 h (p = 0.042), number of proximal anastomoses < or = 2 (p = 0.018), operation time < or = 5 h (p = 0.044) and continuous versus intermittent cross-clamp technique (p = 0.024). There was also a trend with regard to recipient artery diameter > 1.5 mm (p = 0.063), serum cholesterol < or = 225 mg/dl (p = 0.084) and single versus sequential or Y vein graft (p = 0.060). Factors not predictive of 3-year patency were age, race, smoking history, high density lipoprotein cholesterol, vein source (thigh vs. calf), coronary artery grafted and aspirin treatment. Of all the predictors obtained in the univariate analysis, the only variables that were sufficient to yield a good model within the multivariate analysis were solution temperature (p = 0.004), serum cholesterol (p = 0.024), number of proximal anastomoses (p = 0.032) and recipient artery diameter (p = 0.034). CONCLUSIONS For a patient with patent vein grafts 7 to 10 days after the operation, predictors of 3-year graft patency are more closely related to operative techniques and underlying disease and not to aspirin treatment.

The Development Of A Digital Video Subtraction System For Intravenous Angiography

A system is under development for a relatively non-invasive technique for the assessment of atherosclerosis. The principle of this method is digital video x-ray subtraction for the visualization of arterial structures after the intravenous injection of contrast media. The prototype unit for the development of video subtraction techniques has been assembled and preliminary testing has started. Re-sults so far in dogs have shown good visualization of the heart, carotid arteries and renal arteries.

Academic radiology: the reasons to stay or leave.

RATIONALE AND OBJECTIVES To find major reasons why junior academic radiologists leave academia for private practice and to suggest future changes to motivate them to stay. MATERIALS AND METHODS 2000 surveys were sent to every tenth member of the Radiological Society of North America (RSNA) who completed training within the past decade. Those in academic institutions and those who left within 5 years were asked to respond. RESULTS 132 radiologists responded. Thirty-two percent of responders were in academic radiology. Of those in academic radiology, 71% plan to stay at the same institution, 7% are planning to move to another academic institution, 17% are considering private practice, and 5% are leaving for private practice. The main reasons to leave were low pay and lack of academic time. Sixty-eight percent of responders already left academia after an average of 3.28 years. Ninety-five percent feel the decision was good, and 65% would not go back. Forty-nine percent experienced more than 100% pay increase, 60% feel they work harder, and 62% feel quality of life is better. CONCLUSION Significant changes should be made to motivate junior radiologists to stay in academia. Developing leaders in radiology is a must, and should be a top priority. Academic radiologists should not be expected to read private practice volumes and still have time to produce quality research and teaching. Clinical duties should be limited to 32 hours per week. At least 1 day a week should be protected academic time. Efforts should be made to decrease the discrepancy between incomes. Mentoring is important, allowing a smooth transition for junior faculty members to optimize academic progress and lead to promotion.

The statistical analysis of graft patency data in a clinical trial of antiplatelet agents following coronary artery bypass grafting

Because most coronary artery bypass patients receive more than one graft at surgery, it is most important to determine whether statistical analysis of graft patency should be performed on the premise that the multiple grafts within patients are dependent or independent experimental units. Veterans Administration Cooperative Study No. 207 was a multicenter clinical trial comparing four different antiplatelet regimens to placebo in the prevention of graft occlusion following coronary artery bypass grafting. Using the results from the 1-week postoperative angiograms from the Veterans Administration Cooperative Study No. 207, in which there were 3.2 distal anastomoses per patient, we have tested the hypothesis that grafts within patients tend to act dependently with respect to patency or occlusion by comparing the graft patency data to a binomial distribution (i.e., that distribution that would have been manifest if grafts were independent). Because the graft patency results in Study No. 207 significantly deviated from the binomial distribution (p = 0.0003), a more appropriate analysis for graft patency data was applied using a ratio estimate as applied to cluster sampling. The statistical methods used in 11 previous clinical trials of antithrombotic therapy after coronary artery bypass grafting were examined. Only one of the previous studies used such an analysis, and three additional reports attempted to correct for dependency of grafts within patients in their analyses using other statistical methods. In seven of the studies the investigators did not address the potential problem of a dependent relationship between multiple grafts within patients. We conclude that grafts within patients act as dependent experimental units and that the ratio estimate as applied to cluster sampling may be appropriately applied to these data.

Receiver operating characteristic evaluation of computer display of adult portable chest radiographs.

RATIONALE AND OBJECTIVESThe suitability of using an image console monitor for interpretation of adult portable chest radiographs was evaluated with receiver operating characteristic (ROC) analysis and subjective techniques. METHODSRadiologists read 80 chest images, once on a display monitor and once on computed radiography film, for the presence or absence of pneumothorax or atelectasis. Judgments of correct or incorrect positions of tubes and lines were reported, and total viewing time was recorded. RESULTSA statistically significant difference was found in favor of monitor reading for detection of pneumothoraces. Atelectasis detection also was higher with monitor reading, but the difference did not reach statistical significance. Tube/line judgments were equivalent for both modes. Total viewing time was approximately 1 minute longer per image with the monitor. CONCLUSIONSViewing computed radiography images on a workstation monitor does not seem to affect diagnostic accuracy compared with film viewing. Preset image defaults tailored to the individual radiologist could decrease total viewing time to acceptable levels.

Gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts.

RATIONALE AND OBJECTIVES The authors evaluated gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts. METHODS Ten rabbits underwent ligation of the left anterior descending coronary artery. Five animals underwent echocardiography before and after production of myocardial infarct (MI) and four animals had post-MI imaging only. In either case, images were obtained before and after injection of a single dose of 1 mL of gas-filed liposomes. Three radiologists blinded to clinical information reviewed the pre- and postcontrast images and assessed endomyocardial border definition, wall motion, confidence levels for normal versus abnormal wall motion and visualization of papillary muscle and mitral valve. RESULTS Postcontrast scans showed significant improvement (P < .05) in endomyocardial border definition, visualization of wall motion, papillary muscle and mitral valve as well as increased reader confidence level. CONCLUSIONS These results are encouraging and suggest that gas-filled liposomes may be a useful contrast agent for echocardiography.