bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arterial imaging with a new forward-viewing intravascular ultrasound catheter, I. Initial studies.
Authors: Evans J L , Ng K H , Vonesh M J , Kramer B L , Meyers S N , Mills T A , Kane B J , Aldrich W N , Jang Y T , Yock P G 
Published: June 2012

BACKGROUND
Intravascular ultrasound (IVUS) of arteries is limited by the inability of current instruments to visualize beyond the catheter tip. We have developed a prototype 4-mm-diameter forward-viewing IVUS catheter (Cardiovascular Imaging Systems, Sunnyvale, Calif) that has the ability to provide B-mode cross-sectional ultrasound data for a distance of up to 2 cm distal to the catheter tip.

METHODS AND RESULTS
To study the utility of this device, a 20-MHz forward-viewing IVUS catheter was used to examine 13 arterial segments (5 human femoral arteries, 1 human carotid artery, 7 canine arteries) in vitro and 1 phantom. After imaging, all data were compared with histology (Histo). In all cases, the IVUS catheter provided forward-viewing images corresponding to the arterial geometry and demonstrated vascular landmarks and atherosclerotic lesions. There was a good correlation between Histo-determined luminal diameters (LD) and IVUS-determined diameters for a distance of 14 mm ahead of the catheter tip: IVUS LD = 1.0 Histo LD + 1.3 (r = .87).

CONCLUSIONS
These preliminary data suggest that a forward-viewing IVUS catheter is feasible, accurate, and useful for evaluation of arterial geometry distal to the catheter tip.
Echocardiographic predictors of nonrheumatic atrial fibrillation. The Framingham Heart Study.
Authors: Vaziri S M , Larson M G , Benjamin E J , Levy D 
Published: June 2012

BACKGROUND
Although structural heart disease is often present in patients with nonrheumatic atrial fibrillation, the echocardiographic precursors of atrial fibrillation have not been reported previously. In this elderly, population-based cohort, our objective was to examine prospectively the echocardiographic predictors of nonrheumatic atrial fibrillation.

METHODS AND RESULTS
Subjects in the Framingham Heart Study were routinely evaluated with M-mode echocardiography; 1924 subjects, ranging in age from 59 to 90 years, comprised the population at risk. Cox proportional hazards modeling was used to analyze the association of selected echocardiographic features with atrial fibrillation risk after adjustment for age, sex, hypertension, coronary heart disease, congestive heart failure, diabetes, and valvular heart disease. During a mean follow-up interval of 7.2 years, 154 subjects (8.0%) developed atrial fibrillation. Multivariable stepwise analysis identified left atrial size (hazard ratio [HR] per 5-mm increment, 1.39; 95% confidence interval [CI], 1.14 to 1.68), left ventricular fractional shortening (HR per 5% decrement, 1.34; 95% CI, 1.08 to 1.66), and sum of septal and left ventricular posterior wall thickness (HR per 4-mm increment, 1.28; 95% CI, 1.03 to 1.60) as independent echocardiographic predictors of atrial fibrillation. For each of the echocardiographic predictors, risk increased progressively over successive quartiles. Moreover, risk increased markedly when highest-risk-quartile measurements for these features were present in combination; the cumulative 8-year age-adjusted atrial fibrillation rates were 7.3% and 17.0%, respectively, when one and two or more highest-risk-quartile features were present, compared with 3.7% when none was present.

CONCLUSIONS
In this elderly, population-based sample, left atrial enlargement, increased left ventricular wall thickness, and reduced left ventricular fractional shortening were predictive of risk for nonrheumatic atrial fibrillation. These echocardiographic precursors offer prognostic information beyond that provided by traditional clinical atrial fibrillation risk factors.
Dynamic training of skeletal muscle ventricles. A method to increase muscular power for cardiac assistance.
Authors: Guldner N W , Eichstaedt H C , Klapproth P , Tilmans M H , Thuaudet S , Umbrain V , Ruck K , Wyffels E , Bruyland M , Sigmund M 
Published: June 2012

BACKGROUND
Skeletal muscle can be used for cardiac assistance after electrical stimulation over a period of several weeks. This will adapt it to do chronic work with no resulting fatigue. The result of this procedure, however, is a reduction of 80% in muscle power, > 60% in muscle mass, and approximately 85% in contractile speed. To minimize these disadvantages, the following study was done to develop and test a method to dynamically train skeletal muscle ventricles (SMVs).

METHODS AND RESULTS
Barrel-shaped SMVs were tested in 15 Jersey calves. They were made from the latissimus dorsi muscle, which was wrapped around an elastic silicone training device. Six SMVs were used extrathoracically in a single layer and nine intrathoracically in a double layer. With dynamic training preserving contractile speed, the output increased to approximately 5 L/min, the systolic pressure increased to > 200 mm Hg, and power developed to approximately 10 W after 3 months of dynamic training. The contractile speed of dynamically trained SMVs was between 250 and 700 mm/s. The diameter of the latissimus dorsi muscle increased to three times that of the corresponding contralateral muscle.

CONCLUSIONS
The combination of electrical conditioning with dynamic training of the SMVs resulted in a strong muscle pump that did not develop fatigue. Dynamic training for skeletal muscle represents a new and promising method for providing powerful autologous cardiac assist.
Correlates of left ventricular mass in a population sample aged 36 to 37 years. Focus on lifestyle and salt intake.
Authors: Kupari M , Koskinen P , Virolainen J 
Published: June 2012

BACKGROUND
Echocardiographically determined left ventricular (LV) mass predicts adverse cardiovascular events in the general population. We have assessed the correlates of LV mass in a population-based study focusing on lifestyle and salt intake.

METHODS AND RESULTS
A random sample of 120 persons born in 1954 was invited; 93 (42 men) entered the study. The subjects' physical activity and alcohol, tobacco, and coffee consumption were quantified by 2-month dairy follow-up, and sodium intake was quantified by 7-day food records. Blood pressure was averaged for casual cuff measurements made 2 months apart. LV mass was determined by M-mode echocardiography, and stroke volume was determined by Doppler. Hematocrit and serum insulin were measured. In multiple linear regression analysis, LV mass was related positively and independently (P < .05) to body weight, systolic blood pressure, stroke volume, sodium intake, hematocrit, and energy expenditure in leisure-time physical activity. Additional analyses showed that the relation of LV mass to daily sodium intake depended on blood pressure (P < .001 for the interaction); the multiple regression coefficient (+/- SE) was 0.41 +/- 0.11 g.mEq-1 x d-1 (P = .001) in subjects with systolic blood pressure above the population median but statistically nonsignificant (-0.15 +/- 0.10 g.mEq-1 x d-1) in those with lower blood pressure. LV mass was clearly elevated only in persons with both blood pressure and sodium intake above the population medians.

CONCLUSIONS
Body weight, blood pressure, stroke volume, sodium intake, physical activity, and hematocrit are independent predictors of LV mass among unselected persons aged 36 to 37 years. The synergistic interaction of dietary salt with blood pressure suggests that high sodium intake may sensitize the heart to the hypertrophic stimulus of pressure load. Prospective studies are needed to confirm these cross-sectional associations.
A randomized comparison of the effects of gradual prolonged versus standard primary balloon inflation on early and late outcome. Results of a multicenter clinical trial. Perfusion Balloon Catheter Study Group.
Authors: Ohman E M , Marquis J F , Ricci D R , Brown R I , Knudtson M L , Kereiakes D J , Samaha J K , Margolis J R , Niederman A L , Dean L S 
Published: June 2012

BACKGROUND
Observational studies have suggested that prolonged balloon inflation during coronary angioplasty is associated with a high clinical success rate. This randomized clinical trial sought to evaluate the impact of primary gradual and prolonged inflations versus standard short dilatations in patients undergoing elective angioplasty.

METHODS AND RESULTS
In phase 1 of the study, patients were randomized to receive two to four standard (1 minute) dilatations or one or two prolonged (15 minutes) dilatations after a perfusion balloon had been placed across a single target lesion. Patients with unsuccessful angiographic appearance after phase 1 dilatations had further dilatations in phase 2. Patients were followed for 6 to 12 months after the procedure. Of 478 patients, 242 received a median of one prolonged dilatation of 15 minutes' duration, and 236 received three dilatations for a median of 1 minute. Patients assigned to prolonged dilatations had a higher success rate (< or = 50% residual visual stenosis) (95% versus 89%; P = .016), less severe residual stenosis by quantitative angiography (median [25th and 75th percentiles], 35% [26%, 42%] versus 38% [30%, 46%]; P = .001), and a lower rate of major dissections (3% versus 9%; P = .003) at the end of phase 1. A total of 114 patients had further dilatations in phase 2-43 in the prolonged arm and 71 in the standard arm. The final procedural success rate was 98% with both primary dilatation strategies, which included additional maneuvers such as prolonged dilatations in the patients randomized to the primary standard dilatation. Overall, 320 of 416 patients (77%) who were discharged after a successful procedure without any in-hospital event (death, myocardial infarction, coronary artery bypass graft surgery, abrupt closure, or repeat angioplasty in target vessel) returned for follow-up angiography. The restenosis rate (> 50% residual visual stenosis) was 44% (95% confidence interval, 37% to 52%) in the prolonged dilatation group and 44% (36% to 52%) in the standard dilatation group. The primary angiographic end point of failure at the end of phase 1, abrupt closure, or restenosis throughout the study period was similar in both groups (prolonged, 51%; standard, 49%; P = .62). The secondary end point of absence of clinical events (death, nonfatal myocardial infarction, coronary artery bypass graft surgery, or repeat angioplasty in target vessel) also was similar (prolonged, 66%; standard, 74%; P = .15).

CONCLUSIONS
Primary gradual and prolonged dilatations caused less arterial trauma with a modestly larger arterial lumen compared with standard dilatations. This initial improvement in angiographic appearance did not lead to a significant reduction in restenosis or clinical adverse events during follow-up.
Enhanced cholinergic cutaneous vasodilation in Raynaud's phenomenon.
Authors: Khan F , Coffman J D 
Published: June 2012

BACKGROUND
Vasodilator function was determined in patients with Raynaud's phenomenon during intra-arterial infusions of the endothelium-dependent and -independent vasodilators, methacholine and sodium nitroprusside, respectively. Reactive hyperemia, induced by 5 minutes of arterial occlusion with exercise, was also measured.

METHODS AND RESULTS
Total blood flow was measured in the fingertip and forearm by venous occlusion plethysmography, and blood flow in the forearm skin was determined with laser Doppler flowmetry. Basal fingertip blood flow was not significantly different between control subjects and patients with Raynaud's phenomenon. Infusions of methacholine had no significant effect on fingertip blood flow in control subjects, whereas patients with Raynaud's phenomenon showed a significant increase in fingertip blood flow. Basal total forearm blood flow was significantly lower in patients with Raynaud's phenomenon than in control subjects. Infusions of methacholine and sodium nitroprusside produced dose-related increases in total forearm blood flow that were of similar magnitudes in the two groups, as were the reactive hyperemic responses. Laser Doppler measurements of forearm skin blood flow, however, showed a significantly greater vasodilator response to methacholine in patients with Raynaud's phenomenon than in control subjects. Infusions of sodium nitroprusside produced a relatively small vasodilator response in the skin of the forearm that was smaller than that to methacholine and not significantly different between the two groups.

CONCLUSIONS
In Raynaud's phenomenon, a greater vasodilator response to infusions of methacholine in the fingertip, where changes in blood flow mainly reflect those of skin, and in the skin of the forearm may reflect increased responsiveness of cutaneous blood vessels to stimulation of the endothelium. The mechanism involved is unclear but may result from a general abnormality of blood vessels in the skin, which is related to the pathophysiology of cutaneous vasospasm.
Ischemic preconditioning protects against coronary endothelial dysfunction induced by ischemia and reperfusion.
Authors: Richard V , Kaeffer N , Tron C , Thuillez C 
Published: June 2012

BACKGROUND
Repetitive, brief periods of ischemia and reperfusion ("preconditioning") increase the resistance of myocardial tissue to subsequent prolonged ischemic episodes and limit infarct size. We investigated whether preconditioning also protects against coronary endothelial dysfunction induced by ischemia and reperfusion.

METHODS AND RESULTS
Experiments were performed in four groups of rats (n = 8 in each group): group 1 rats underwent sham surgery, group 2 rats were subjected to 20 minutes of left coronary artery occlusion without reperfusion, group 3 rats underwent 20 minutes of occlusion followed by 1 hour of reperfusion, and group 4 rats (preconditioning group) underwent the same protocol as group 3 rats, preceded by three cycles of 5 minutes of ischemia and 5 minutes of reperfusion. At the end of the experiments, coronary segments (internal diameter, 250 to 300 microns) were removed distal to the occlusion site and mounted in wire myographs for isometric tension recording. Relaxations induced by increasing concentrations of acetylcholine, the calcium ionophore A23187, or the nitric oxide (NO) donor SIN-1 were determined in arteries precontracted by serotonin. Basal NO release was estimated by measuring contractions to NG-nitro L-arginine methyl ester (L-NAME). In addition, we determined the effect of preconditioning on infarct size in two additional groups that were subjected to the same protocols as those of groups 3 and 4. In those animals, area at risk (India ink injection) and infarct size (triphenyltetrazolium stain) were determined by computerized analysis of enlarged sections after video acquisition. Preconditioning markedly limited infarct size (percent of area at risk: controls, 57 +/- 2; preconditioning, 2.2 +/- 0.6; P < .01). Ischemia (without or with reperfusion) or preconditioning did not affect the coronary responses to L-NAME, serotonin, A23187, or SIN-1. Ischemia without reperfusion did not modify the relaxations to acetylcholine (maximal relaxation: sham, 58 +/- 4%; ischemia, 56 +/- 7%; P = NS). In contrast, ischemia followed by reperfusion markedly impaired the response to acetylcholine (26 +/- 6%; P < .01 versus sham). This impaired response was restored by preconditioning (maximal relaxation: 59 +/- 9%; P = NS versus sham; P < .01 versus ischemia/reperfusion).

CONCLUSIONS
In addition to protecting myocardial cells, preconditioning also protects coronary endothelial cells against ischemia/reperfusion injury.
Exposure to environmental tobacco smoke increases myocardial infarct size in rats.
Authors: Zhu B Q , Sun Y P , Sievers R E , Glantz S A , Parmley W W , Wolfe C L 
Published: June 2012

BACKGROUND
Exposure to environmental tobacco smoke (ETS) has been epidemiologically linked to death from ischemic heart disease in nonsmokers. In this study, we evaluated the influence of 3 days, 3 weeks, and 6 weeks of ETS exposure on myocardial infarct size in a rat ischemia/reperfusion model.

METHODS AND RESULTS
Sprague-Dawley rats exposed to ETS (four Marlboro cigarettes per 15 minutes, 6 hours per day, 5 days per week) for 3 days (n = 24), 3 weeks (n = 21), or 6 weeks (n = 12) and control rats (n = 24, n = 21, and n = 12, respectively) were subjected to 35 minutes of left coronary artery occlusion and 2 hours of reperfusion. Infarct size and risk area were determined by triphenyltetrazolium chloride and phthalocyanine blue staining, respectively. Air nicotine, carbon monoxide, and total particulates were measured during ETS exposure. Serum lipids, plasma carbon monoxide hemoglobin (COHb), nicotine, and cotinine concentrations were measured in additional groups (6 to 13 rats each) exposed to 3 days, 3 weeks, or 6 weeks of ETS and controls. Average air nicotine, carbon monoxide, and total particulate concentrations were 1103 micrograms/m3, 92 ppm, and 60 mg/m3 for the ETS-exposed rats. Infarct size (infarct mass/risk area x 100%) increased significantly in the ETS groups compared with the control groups in a dose-dependent manner (P = .023), with longer exposure associated with larger infarct size. Infarct size nearly doubled with 6 weeks of ETS exposure (61 +/- 5% versus 34 +/- 3% for control, mean +/- SEM). Plasma COHb, nicotine, and cotinine levels increased significantly in the ETS groups in a dose-dependent manner (all P < .001).

CONCLUSIONS
Exposure to passive smoking increases myocardial infarct size in a rat model of ischemia and reperfusion. This increase of infarct size exhibited a dose-response relation. These results are consistent with epidemiological studies demonstrating that ETS increases the risk of heart death.
Dietary iron intake and risk of coronary disease among men.
Authors: Ascherio A , Willett W C , Rimm E B , Giovannucci E L , Stampfer M J 
Published: June 2012

BACKGROUND
We prospectively studied iron intake in relation to the incidence of coronary disease in a 4-year follow-up of 44,933 men (with no previous history of cardiovascular disease) aged 40 to 75 years in 1986 who completed a food frequency questionnaire at baseline.

METHODS AND RESULTS
We documented 844 incident cases of coronary disease (249 nonfatal myocardial infarctions, 137 coronary disease fatalities, and 458 bypass operations or angioplasties). After adjustment for established risk factors, there was no significant association between total iron intake and risk of coronary heart disease. Men in the highest quintile of total intake (median, 37 mg/d) had a relative risk (RR) of fatal coronary disease or nonfatal myocardial infarction of 0.73 (95% confidence intervals [CI], 0.51, 1.06) compared with men in the lowest quintile of intake (median, 11 mg/d). Dietary intake of heme iron--mainly from red meat--also was not significantly associated with risk of coronary heart disease. However, incidence of fatal coronary disease or nonfatal myocardial infarction was higher among men in the top quintile of heme iron intake compared with men in the lowest quintile (RR, 1.42; 95% CI, 1.02, 1.98). This association remained after adjustment for dietary cholesterol and fats. Heme iron but not total iron intake was positively correlated with serum ferritin among 123 members of the cohort who participated in a validation study.

CONCLUSIONS
These results do not support the hypothesis that dietary iron in general increases coronary risk in men; they are consistent, however, with an increased risk of myocardial infarction among men with higher intake of heme iron, which is itself positively associated with iron stores.
Temporal trends (1975 through 1990) in the incidence and case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction. A communitywide perspective.
Authors: Chiriboga D , Yarzebski J , Goldberg R J , Gore J M , Alpert J S 
Published: June 2012

BACKGROUND
As part of a population-based study of acute myocardial infarction, we examined changes over time in the incidence and in-hospital case-fatality rates of primary ventricular fibrillation complicating acute myocardial infarction.

METHODS AND RESULTS
Patients with validated acute myocardial infarction hospitalized at 16 hospitals in the Worcester, Mass, metropolitan area between 1975 and 1990 comprised the study sample. During the 15-year study period, 5.1% of patients developed primary ventricular fibrillation in the setting of uncomplicated acute myocardial infarction, with this rate remaining relatively constant over time. Both age- and multivariable-adjusted analyses showed no significant trend in the incidence rates of primary ventricular fibrillation during the study period. The in-hospital case-fatality rate for patients with primary ventricular fibrillation was significantly elevated compared with the rate for those without primary ventricular fibrillation and uncomplicated acute myocardial infarction (48.3% versus 1.5%, P < .001). No significant change over time was noted in in-hospital case-fatality rates associated with primary ventricular fibrillation while controlling for a variety of short-term prognostic factors.

CONCLUSIONS
The results of this communitywide observational study suggest that neither the incidence nor the prognosis associated with primary ventricular fibrillation resulting from acute myocardial infarction has improved over time.
Variable expression of the estrogen receptor in normal and atherosclerotic coronary arteries of premenopausal women.
Authors: Losordo D W , Kearney M , Kim E A , Jekanowski J , Isner J M 
Published: June 2012

BACKGROUND
The relative absence of coronary atherosclerosis in premenopausal women has been established. Estrogen is presumed to play a role in the protection of coronary arteries from atherosclerosis, and part of this protective effect appears to be mediated by amelioration of serum lipid profiles. However, all of the atheroprotective effect of estrogen is not explained by alteration of serum lipids. In this study, we attempt to identify evidence of estrogen receptors in coronary artery specimens of female patients and in human vascular smooth muscle cells.

METHODS AND RESULTS
Postmortem coronary artery specimens were obtained from premenopausal (n = 18) and postmenopausal (n = 22) women who died with significant coronary artery disease (n = 19) and from noncardiac causes with normal coronary arteries (n = 21). Sections were examined for evidence of estrogen receptor expression using a monoclonal antibody stain. Radioligand binding assays for estrogen receptors were performed on human vascular smooth muscle cells in culture, and gel retardation assays were performed to confirm the presence of functional estrogen receptors. Estrogen receptor expression was identified by immunostaining in a total of 21 coronary arteries, with the majority of normal arteries (15 positive of 21 total, P = .0117) demonstrating evidence of estrogen receptor expression. Conversely, a minority (6 of 19, P = NS) of atherosclerotic arteries were positive for estrogen receptor expression. Furthermore, the relation between estrogen receptor expression and absence of coronary atherosclerosis was most evident in premenopausal subjects, with 10 of 12 normal arteries in this group demonstrating evidence of estrogen receptors, whereas only 1 of 6 atherosclerotic coronary arteries was positive (P = .0062). Radioligand binding assays confirmed the presence of estrogen receptors at significant concentrations in intact human vascular smooth muscle cells. Gel retardation assays also documented the presence of functional estrogen receptors in extracts from human vascular smooth muscle cells.

CONCLUSIONS
This investigation provides evidence of estrogen receptors in smooth muscle cells from human coronary arteries. The demonstrated relation between the presence of the receptors and the absence of atherosclerosis in premenopausal women suggests that these receptors may play a functional role in coronary atheroprotection.