bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myocardial metabolic, hemodynamic, and electrocardiographic significance of reversible thallium-201 abnormalities in hypertrophic cardiomyopathy.
Authors: Cannon R O , Dilsizian V , O'Gara P T , Udelson J E , Schenke W H , Quyyumi A , Fananapazir L , Bonow R O 
Published: June 2012

BACKGROUND
Exercise-induced abnormalities during thallium-201 scintigraphy that normalize at rest frequently occur in patients with hypertrophic cardiomyopathy. However, it is not known whether these abnormalities are indicative of myocardial ischemia.

METHODS AND RESULTS
Fifty patients with hypertrophic cardiomyopathy underwent exercise 201Tl scintigraphy and, during the same week, measurement of myocardial lactate metabolism and hemodynamics during pacing stress. Thirty-seven patients (74%) had one or more 201Tl abnormalities that completely normalized after 3 hours of rest; 26 had regional myocardial 201Tl defects, and 26 had apparent left ventricular cavity dilatation with exercise, with 15 having coexistence of these abnormal findings. Of the 37 patients with reversible 201Tl abnormalities, 27 (73%) had metabolic evidence of myocardial ischemia during rapid atrial pacing (myocardial lactate extraction of 0 mmol/l or less) compared with four of 13 patients (31%) with normal 201Tl scans (p less than 0.01). Eleven patients had apparent cavity dilatation as their only 201Tl abnormality; their mean postpacing left ventricular end-diastolic pressure was significantly higher than that of the 13 patients with normal 201Tl studies (33 +/- 5 versus 21 +/- 10 mm Hg, p less than 0.001). There was no correlation between the angiographic presence of systolic septal or epicardial coronary arterial compression and the presence or distribution of 201Tl abnormalities. Patients with ischemic ST segment responses to exercise had an 80% prevalence rate of reversible 201Tl abnormalities and a 70% prevalence rate of pacing-induced ischemia. However, 69% of patients with nonischemic ST segment responses had reversible 201Tl abnormalities, and 55% had pacing-induced ischemia.

CONCLUSIONS
Reversible 201Tl abnormalities during exercise stress are markers of myocardial ischemia in hypertrophic cardiomyopathy and most likely identify relatively underperfused myocardium. In contrast, ST segment changes with exercise and systolic compression of coronary arteries on angiography are unreliable markers of inducible myocardial ischemia in hypertrophic cardiomyopathy. Apparent cavity dilatation during 201Tl scintigraphy may indicate ischemia-related changes in left ventricular filling, with elevation in diastolic pressures and endocardial compression.
Left ventricular midwall mechanics in systemic arterial hypertension. Myocardial function is depressed in pressure-overload hypertrophy.
Authors: Shimizu G , Hirota Y , Kita Y , Kawamura K , Saito T , Gaasch W H 
Published: June 2012

BACKGROUND
Left ventricular (LV) midwall geometry has been described conventionally as the sum of the chamber radius and half of the wall thickness; this convention is based on the assumption of uniform transmural thickening during systole. However, theoretical considerations and experimental data indicate that the inner half (inner shell) of the LV wall thickens more than the outer half (outer shell). Thus, an end-diastolic circumferential midwall fiber exhibits a relative migration toward the epicardium during systole. As a result, the conventional method provides an overestimate of the extent of the midwall fiber shortening.

METHODS AND RESULTS
We developed an ellipsoidal model with a concentric two-shell geometry (nonuniform thickening) to assess midwall fiber length transients throughout the cardiac cycle. This modified midwall method was used in the analysis of LV cineangiograms from 15 patients with systemic arterial hypertension and 14 normal subjects. Study groups were classified according to LV mass index (LVMI): 14 normal subjects (group I), eight hypertensive patients with a normal LVMI (group II), and seven hypertensive patients with an increased LVMI (group III). There were no significant differences in LV end-diastolic pressure or volume among the three groups; the ejection fraction was slightly greater in group II (70 +/- 5%) than in groups I (65 +/- 8%) and III (66 +/- 4%), but this trend did not achieve statistical significance. Values for endocardial and conventional midwall fractional shortening (FS) were also similar in the three groups. By contrast, FS by the concentric two-shell geometry (modified midwall method) in group III (16 +/- 2%) was significantly less than that seen in groups I and II (21 +/- 4% and 21 +/- 5%, respectively; both p less than 0.05). This difference achieves greater importance when it is recognized that mean systolic circumferential stress was lower in group III (151 +/- 22 g/cm2) than in groups I and II (244 +/- 37 g/cm2 and 213 +/- 38 g/cm2, respectively; both p less than 0.01). The midwall stress-shortening coordinates in six of the seven group III patients were outside the 95% confidence limits for the normal (group I) subjects. Thus, despite a normal ejection fraction, systolic function is subnormal in hypertensive patients with LV hypertrophy.

CONCLUSIONS
Chamber dynamics provide an overestimate of myocardial function, especially when LV wall thickness is increased. This is due to a relatively greater contribution of inner shell thickening in pressure-overload hypertrophy.
Use of endovascular stents in congenital heart disease.
Authors: O'Laughlin M P , Perry S B , Lock J E , Mullins C E 
Published: June 2012

BACKGROUND
Balloon expandable intravascular stents have been used to support vessel walls in coronary and peripheral arteries in adults. The purpose of this study was to examine the efficacy and safety of these stents in the treatment of congenital heart disease.

METHODS AND RESULTS
Forty-five stents were placed in 30 patients, who were 0.2-30.2 years old (weight, 3.5-76 kg). Patients with areas of stenosis that were difficult to approach surgically were chosen. Stents were mounted over balloons and placed by standard catheterization techniques. Twenty-three patients had branch pulmonary artery stenosis. Thirty-six stents were placed successfully and had reduced pressure gradients from 50.6 +/- 24 to 15.9 +/- 13.4 mm Hg. Five patients had stents placed after atrial surgery: three in obstructed Fontan repairs, one at the superior vena cava-right atrial junction after sinus venous defect repair, and one at the site of a Glenn shunt. Atrial stents reduced pressure gradients from 9.8 +/- 8.2 to 2.0 +/- 2.6 mm Hg. One patient had a stent placed in the descending aorta after coarctation dilation, and the pressure gradient was reduced from 50 to 25 mm Hg. One patient had pulmonary vein dilation with stent placement. Two stents migrated at the time of placement; one required surgical removal, and one was anchored in place by balloon dilation. One patient died within 24 hours of catheterization because of thrombus obstruction of the Fontan repair. Nine patients have undergone recatheterization. All stented vessels have remained at the same caliber as at original stent placement.

CONCLUSIONS
We conclude that balloon expandable stents are useful in selected postoperative stenoses in congenital heart disease.
Histopathologic validation of angioscopy and intravascular ultrasound.
Authors: Siegel R J , Ariani M , Fishbein M C , Chae J S , Park J C , Maurer G , Forrester J S 
Published: June 2012

BACKGROUND
To establish a histopathologic basis for angioscopic and ultrasound image interpretation we studied 70 postmortem human arterial segments in vitro.

METHODS AND RESULTS
We used 7- to 9-French fiber-optic angioscopes and 20- to 30-MHz intravascular ultrasound imaging catheters. Three observers assigned an angioscopic and ultrasound image classification to each vessel segment. The image and histological classification categories were then compared. The sensitivity, specificity, and accuracy of both methods separately or in combination for normal vessels were each greater than or equal to 95%. The predictive value was better for angioscopy than for ultrasound due to incorrect ultrasound interpretations of normal anatomy in the presence of thrombus. For stable atheroma the sensitivity, specificity, and accuracy of the individual methods were each greater than 90%. However, both angioscopy and ultrasound had classification errors in that disrupted atheroma was identified and classified as stable atheroma. Consequently, the predictive value was 74% for angioscopy and 78% for ultrasound. For disrupted atheroma the sensitivities for angioscopy and ultrasound were only moderate (73% and 81%, respectively), whereas the specificity, accuracy, and predictive value were each high (greater than 90%). For thrombus detection, the specificity, accuracy, and predictive value were high (greater than 93%) for each method. The sensitivity of angioscopy was 100%. However, sensitivity was lower for ultrasound (57%) due to false-negative interpretation of laminar clots in normal vessels and an inability to distinguish disrupted or stable atheroma from intraluminal thrombus.

CONCLUSIONS
Contingency analyses showed that each imaging method alone or combined had significant agreement with the results obtained from histology (p less than 0.001). When assessing all cases in which angioscopy and ultrasound were concordant, there was a 92% agreement with the histological classification.
High density lipoprotein metabolism in endurance athletes and sedentary men.
Authors: Thompson P D , Cullinane E M , Sady S P , Flynn M M , Chenevert C B , Herbert P N 
Published: June 2012

BACKGROUND
Endurance athletes have higher high density lipoprotein (HDL) concentrations than sedentary controls. To examine the mechanism for this effect, we compared HDL apoprotein metabolism in 10 endurance athletes aged 34 +/- 6 years (mean +/- SD) and 10 sedentary men aged 36 +/- 8 years.

METHODS AND RESULTS
Subjects were maintained on controlled diets for 4 weeks, and metabolic studies using autologously labeled 125I HDL were performed during the final 2 weeks. Lipids and lipoproteins were measured daily during these 2 weeks, and the average of 14 values was used in the analysis. HDL cholesterol (58 +/- 14 versus 41 +/- 10 mg/dl), HDL2 cholesterol (26 +/- 10 versus 12 +/- 8 mg/dl), and apolipoprotein A-I (apo A-I) (144 +/- 18 versus 115 +/- 22 mg/dl) were higher in the athletes, whereas triglyceride concentrations (60 +/- 18 versus 110 +/- 48 mg/dl) were lower (p less than 0.01 for all). Postheparin lipoprotein lipase activity was not different, but hepatic triglyceride lipase activity was 27% lower (p less than 0.06) in the athletes. The athletes' mean clearance rate of triglycerides after an infusion of Travamulsion (1 ml/kg) was nearly twofold that of the inactive men (5.8 +/- 1.5 versus 3.2 +/- 0.9%/min, p less than 0.001). There was no differences in HDL apoprotein synthetic rates, whereas the catabolic rates of both apo A-I (0.15 +/- 0.02 versus 0.22 +/- 0.05 pools per day, p less than 0.01) and apolipoprotein A-II (apo A-II) (0.15 +/- 0.02 versus 0.20 +/- 0.04 pools per day, p less than 0.05) were reduced in the trained men. Apo A-I and apo A-II half-lives correlated with HDL cholesterol in each group (r greater than 0.76, p less than 0.05 for all) but not consistently with lipase activities or fat clearance rates. This relation between apoprotein catabolism and HDL cholesterol was strongest at HDL cholesterol concentrations of less than 60 mg/dl.

CONCLUSIONS
We conclude that higher HDL levels in active men are associated with increased HDL protein survival. The mechanisms mediating this effect require better definition, and other factors appear to contribute to HDL cholesterol and protein concentrations among individual subjects.
Prediction of outcome after mitral valve replacement in patients with symptomatic chronic mitral regurgitation. The importance of left atrial size.
Authors: Reed D , Abbott R D , Smucker M L , Kaul S 
Published: June 2012

BACKGROUND
The ability to predict outcome after mitral valve replacement remains limited in patients with symptomatic chronic mitral regurgitation. The aims of this study were to determine the preoperative predictors of postoperative cardiac-related mortality and to assess the additive prognostic value of tests performed in such patients.

METHODS AND RESULTS
Accordingly, 176 patients (mean age, 57 +/- 14 years) who underwent mitral valve replacement were followed up for 3.8 +/- 0.5 years. Four categories of variables were analyzed to predict postoperative cardiac-related mortality: clinical, laboratory, two-dimensional echocardiographic (2DE), and cardiac catheterization. There were 39 cardiac-related deaths (29 due to congestive heart failure and 10 sudden). When the four categories were analyzed separately, two clinical, one laboratory, two 2DE, and one catheterization variable best predicted postoperative death. When these six variables were examined simultaneously, only three (one clinical and two 2DE) remained significant predictors of cardiac-related mortality: presence of pulmonary rales, left atrial size, and the ratio of left ventricular wall thickness to left ventricular cavity dimension in end systole. A model based on these three variables may predict cardiac-related death with considerable accuracy. Laboratory data did not add to clinical information for predicting death. 2DE variables provided significant additional information in this regard (p less than 0.001). Further addition of catheterization variables was not useful. Prognostic value did not change significantly when 50 patients with prior mitral valve surgery or 49 patients undergoing concomitant aortic valve replacement or coronary artery bypass surgery were excluded from analysis.

CONCLUSIONS
We conclude that 1) measures of both left ventricular systolic function and left atrial size are equally important in predicting postoperative cardiac-related mortality in patients with symptomatic chronic mitral regurgitation undergoing mitral valve replacement; 2) left atrial size may be important because it reflects the "history" (severity and duration) of mitral regurgitation; 3) 2DE assessment of left atrial size and left ventricular function provides prognostic information that is significantly greater than that obtained from clinical and laboratory parameters alone; the addition of catheterization variables does not increase the prognostic value of the clinical and 2DE data.
Preconditioning causes improved wall motion as well as smaller infarcts after transient coronary occlusion in rabbits.
Authors: Cohen M V , Liu G S , Downey J M 
Published: June 2012

BACKGROUND
A brief coronary occlusion before a more prolonged occlusion results in less myocardial infarction than the longer occlusion alone. However, the effects of this preconditioning on recovery of systolic function after coronary occlusion have not been determined.

METHODS AND RESULTS
Ultrasonic crystals implanted in rabbit myocardium measured segment length in the distribution of a branch of the left coronary artery that was fitted with a snare occluder. Rabbits were randomly allocated to either nonpreconditioned or preconditioned groups. Rabbits in the latter group underwent preconditioning with a 5-minute coronary occlusion followed by 10 minutes of reperfusion. Then the coronary artery was occluded for 20 minutes in all rabbits, after which it was allowed to reperfuse for 90 minutes. The hearts were then excised, and infarct size was measured by staining with triphenyltetrazolium chloride. During coronary occlusion, all hearts except one demonstrated either akinesis or paradoxical bulging. Five minutes after release of the 20-minute occlusion, active shortening had returned in the preconditioned rabbits and averaged 27.9 +/- 16.6% of baseline shortening. At the same time, paradoxical lengthening persisted in nonpreconditioned rabbits (-15.5 +/- 19.8% of baseline). By the end of the 90-minute reperfusion period, segment shortening averaged 40.1 +/- 8.4% of baseline in preconditioned rabbits and only 6.2 +/- 12.0% in nonpreconditioned rabbits (p less than 0.05). Infarct size as a percentage of risk area was significantly smaller in preconditioned rabbits as well (3.0 +/- 1.6% versus 28.8 +/- 7.0%, p less than 0.002) and likely accounted for the improved shortening.

CONCLUSIONS
We conclude that a brief coronary occlusion before a more prolonged occlusion results in not only reduced infarct size but also significantly better recovery of systolic function.
Dipyridamole thallium-201 scintigraphy as a preoperative screening test. A reexamination of its predictive potential. Study of Perioperative Ischemia Research Group.
Authors: Mangano D T , London M J , Tubau J F , Browner W S , Hollenberg M , Krupski W , Layug E L , Massie B 
Published: June 2012

BACKGROUND
We examined the value of dipyridamole thallium-201 (201Tl) scintigraphy as a preoperative screening test for perioperative myocardial ischemia and infarction.

METHODS AND RESULTS
We prospectively studied 60 patients undergoing elective vascular surgery. We performed 201Tl scintigraphy preoperatively and blinded all treating physicians to the results. Historical, clinical, laboratory, and physiological data were gathered throughout hospitalization. Myocardial ischemia was assessed during the intraoperative period using continuous 12-lead electrocardiography (ECG) and transesophageal echocardiography (TEE) and during the postoperative period using continuous two-lead ambulatory ECG. Adverse cardiac outcomes (cardiac death, myocardial infarction, unstable angina, severe ischemia, or congestive heart failure) were assessed daily throughout hospitalization. Twenty-two patients (37%) had defects that improved or reversed on delayed scintigrams (redistribution defects), 18 (30%) had persistent defects, and 20 (33%) had no defects on 201Tl scintigraphy. There was no association between redistribution defects and adverse cardiac outcomes: 54% (seven of 13) of adverse outcomes occurred in patients without redistribution defects, and the risk of an adverse outcome was not significantly increased in patients with redistribution defects (relative risk 1.5, 95% confidence interval 0.6-3.9, p = 0.43). Consistent with these findings, there was also no association between redistribution defects and perioperative ischemia: 54% (19 of all 35) of perioperative ECG and TEE ischemic episodes and 58% (14 of 24) of severe ischemic episodes occurred in patients without redistribution defects. The sensitivity of 201Tl scintigraphy for perioperative ischemia and adverse outcomes ranged from 40% to 54%, specificity from 65% to 71%, positive predictive value from 27% to 47% and negative predictive value from 61% to 82%.

CONCLUSIONS
These results differ from those of previous studies and suggest that the routine use of 201Tl scintigraphy for preoperative screening of patients undergoing vascular surgery may not be warranted.
Starting aspirin therapy after operation. Effects on early graft patency. Department of Veterans Affairs Cooperative Study Group.
Authors: Goldman S , Copeland J , Moritz T , Henderson W , Zadina K , Ovitt T , Kern K B , Sethi G , Sharma G V , Khuri S 
Published: June 2012

BACKGROUND
Although 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 RESULTS
Patients 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).

CONCLUSIONS
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.
Blood platelet count and function are related to total and cardiovascular death in apparently healthy men.
Authors: Thaulow E , Erikssen J , Sandvik L , Stormorken H , Cohn P F 
Published: June 2012

BACKGROUND
Experimental animal and clinical studies indicate that blood platelets have an important role in atherosclerosis and formation of thrombi. Prospective studies presenting evidence of an association between blood platelet count and cardiovascular mortality have not been performed.

METHODS AND RESULTS
From 1973 to 1975, blood platelets were counted, and their responsiveness to aggregating agents was studied in healthy middle-aged men. The aim was to assess the possible association between these variables and coronary heart disease. At 13.5 years of follow up, a significantly higher coronary heart disease mortality was observed among the 25% of subjects with the highest platelet counts. Platelet aggregation performed in a random subsample (150 of the 487 men), moreover, revealed that the 50% with the most rapid aggregation response after ADP stimulation had significantly increased coronary heart disease mortality compared with the others. These associations could not be explained by differences in age, lipids, blood pressure, or smoking habits.

CONCLUSIONS
The present study is the first to present conclusive, prospective evidence of an association between platelet concentration and aggregability and long-term incidence of fatal coronary heart disease in a population of apparently healthy middle-aged men.