bluuebunny/crossref_metadata_2025_split huggingface dataset:
Race and prognosis after myocardial infarction. Results of the thrombolysis in myocardial infarction (TIMI) phase II trial.
Authors: Taylor H A , Chaitman B R , Rogers W J , Kern M J , Terrin M L , Aguirre F V , Sopko G , McMahon R , Ross R N , Bovill E C 
Published: June 2012

BACKGROUND
To better understand the role of race/ethnicity in survival after acute myocardial infarction, we compared clinical and laboratory data, response to thrombolytic therapy, and clinical outcome in 2885 patients participating in the Thrombolysis in Myocardial Infarction Phase II (TIMI II) Trial among three groups of patients (2564 whites, 174 blacks, and 147 Hispanics).

METHODS AND RESULTS
Differences were found in baseline characteristics among the three groups including (1) age (mean age for whites, 57.2 years; blacks, 54.8 years; Hispanics, 52.8 years; P < .001), (2) sex (percentage of women for whites, 17.6; blacks, 28.7; Hispanics, 14.3; P < .001), and (3) risk factor prevalence: current smoking (percent for whites, 49.4; blacks, 62.1; Hispanics, 55.1; P < .003), history of hypertension (percent for whites, 36.6; blacks, 55.7; Hispanics, 39.5; P < .001), and diabetes mellitus (percent for whites, 11.9; blacks, 22.4; Hispanics, 19.7; P < .001). Changes in hemostatic factors 5 hours after infusion of recombinant tissue plasminogen activator (rt-PA) revealed a more profound fall in fibrinogen levels in black patients compared with the response seen in Hispanic or white patients (mean change in fibrinogen +/- SD, mg/dL: 151.3 +/- 107.4, 112.2 +/- 97.0, 109.4 +/- 98.6; P < .001, respectively) without more frequent infarct-related artery patency or hemorrhagic complications. Mortality was similar in the white, black, and Hispanic patients through the first year after adjustment for baseline variables.

CONCLUSIONS
TIMI II data yield evidence that (1) corroborates published reports of a high prevalence of classic cardiovascular risk factors among minority patients with acute myocardial infarction, (2) there is a greater decrease in fibrinogen levels 5 hours after the start of rt-PA infusion among black patients than in white and Hispanic patients without evidence of more frequent infarct-related artery patency or hemorrhagic complications, and (3) thrombolytic therapy with appropriate supplemental measures is associated with comparable 1-year mortality in white, black, and Hispanic patients.
Initial experience with a direct antithrombin, Hirulog, in unstable angina. Anticoagulant, antithrombotic, and clinical effects.
Authors: Lidón R M , Théroux P , Juneau M , Adelman B , Maraganore J 
Published: June 2012

BACKGROUND
Currently available antithrombotic therapy for unstable angina is unwieldy and occasionally ineffective. This study was designed to investigate the potential of Hirulog, a new synthetic specific antithrombin agent, for the management of this condition.

METHODS AND RESULTS
A total of 55 patients in the acute phase of unstable angina received intravenous Hirulog according to one of two protocols. In an acute dose-escalating study, 0.02, 0.05, 0.1, 0.25, and 0.5 mg.kg-1 x h-1, each for 30 minutes, were infused in 15 patients. Prolongation of activated partial thromboplastin time (aPTT) (r = .95), fibrinopeptide A inhibition (r = .96), and Hirulog plasma levels (r = .91) correlated closely with the dose infused, with significant changes compared with baseline appearing at doses of 0.25 mg.kg-1 x h-1 and higher. The purposes of the second protocol were to determine whether the anticoagulant and antithrombotic effects of the drug were sustained during a 72-hour infusion and to assess whether such treatment prevented the complications of unstable angina. Based on the initial study, we planned to give a dose of 0.25 mg.kg-1 x h-1 to each patient until 2 patients failed therapy, then successively higher doses until a 95% success rate was achieved or adverse effects intervened, increasing the dose after two failures had occurred at each level. Five patients received the 0.25-mg.kg-1 x h-1 dose and 14 the 0.5-mg.kg-1 x h-1 dose before two failures occurred. Failure was observed in only one of 21 patients at the dose of 1 mg.kg-1 x h-1. aPTT (+/- SEM) levels increased to 62 +/- 5, 76 +/- 2, and 98 +/- 3 seconds at the three doses, with minimal intraindividual variation, and Hirulog plasma levels to 1050, 2100, and 4200 mg/mL, respectively. Fibrinopeptide A plasma levels decreased at all doses but more consistently at the dose of 1 mg.kg-1 x h-1. The overall clinical success rate was 87.5%: 60% (3/5) at the low dose, 86% (12/14) at the intermediate dose, and 95% (20/21) at the high dose. No deaths, myocardial infarctions, or bleeding complications occurred.

CONCLUSIONS
In unstable angina patients, Hirulog infusions quickly and reproducibly yield stable, dose-dependent anticoagulant and antithrombotic effects with a favorable clinical efficacy profile.
Ionic mechanisms of electronic inhibition and concealed conduction in rabbit atrioventricular nodal myocytes.
Authors: Liu Y , Zeng W , Delmar M , Jalife J 
Published: June 2012

BACKGROUND
The term "concealed conduction" is used in electrocardiography when a proximal (atrial or ventricular) impulse penetrates the atrioventricular (AV) node but fails to traverse it completely. Its penetration into the node is inferred by its after effects on the propagation of succeeding impulses. Concealed AV nodal conduction is a well-established phenomenon, but its precise cellular and subcellular mechanisms are unknown. It has been suggested that concealed conduction results from a transient impairment of excitability caused by the subthreshold depolarization (ie, electrotonic inhibition) that is elicited downstream of the site of block.

METHODS AND RESULTS
We studied the ionic mechanism of electrotonic inhibition and concealed conduction in single myocytes isolated from the rabbit AV node. Cells were paced using just-threshold current pulses delivered at a constant (basic) cycle length of 1 second. Appropriately timed interpolation of a conditioning pulse of depolarizing but subthreshold current led to failure of the subsequent, previously successful activation. The ability of the subthreshold response to inhibit subsequent excitation was increased when the interval between the conditioning and succeeding pulses was shortened, when the amplitude of the conditioning pulse was increased, or when the inward sodium current was blocked by superfusion with tetrodotoxin (30 microM). Voltage clamp analysis demonstrated that electrotonic inhibition results from partial inactivation of the transient calcium current (ICa.T). Similar results were obtained using a mathematical model (Hodgkin-Huxley type) of the AV nodal myocyte. Additional simulations in a linear array of AV nodal cells showed that when a premature impulse fails to traverse the AV node, the subthreshold depolarization elicited downstream of the site of block may lead to a transient reduction of excitability with consequent delay or block of the succeeding impulse.

CONCLUSIONS
The overall data strongly suggest that some of the electrocardiographic manifestations of concealed AV conduction are the result of electrotonic inhibition of excitability secondary to a transient decrease in ICa.T.
Tetralogy of Fallot with pulmonary atresia. Rehabilitation of diminutive pulmonary arteries.
Authors: Rome J J , Mayer J E , Castaneda A R , Lock J E 
Published: June 2012

BACKGROUND
Patients with tetralogy of Fallot, pulmonary atresia, and diminutive pulmonary arteries are a high-risk group for whom there is no consensus on the correct approach to medical management. The purpose of this report is to review a 14-year experience in the treatment of these patients comparing management schemes.

METHODS AND RESULTS
Between January 1978 and August 1988, 91 patients with tetralogy of Fallot and pulmonary atresia had an adequate evaluation of their pulmonary artery anatomy before any surgical management. Forty-eight of these patients had diminutive pulmonary arteries (38 to 104 mm2/m2) supplied by aortopulmonary collaterals and were managed in four different fashions. Of the 9 patients repaired primarily, 7 died early and the two survivors had poor hemodynamic outcome. Of the 9 patients conservatively managed with no intervention before 5 years of age, 4 died and only 1 had a satisfactory hemodynamic result after repair. Of 10 shunted patients, 3 died and 3 had satisfactory repairs. Since 1984, we have rehabilitated pulmonary arteries with (1) right ventricle to pulmonary artery surgical graft, (2) balloon dilation of residual pulmonary artery stenoses and embolization of collaterals, and (3) surgical closure of ventricular septal defect and repair of remaining obstructions. Of 20 patients so managed, 7 died after various stages, but 10 of 20 had complete repairs. All repaired patients with subsystemic right ventricular pressures had at least one successful pulmonary artery dilation.

CONCLUSIONS
A combined catheter-surgery approach begun at an early age in patients with tetralogy of Fallot and pulmonary atresia with diminutive pulmonary arteries appears to enhance the chances of satisfactory complete repair.
Mitral valve repair in rheumatic disease. The flexible solution.
Authors: Bernal J M , Rabasa J M , Vilchez F G , Cagigas J C , Revuelta J M 
Published: June 2012

BACKGROUND
Mitral valve repair in rheumatic disease is technically more difficult, and there is little information on the long-term stability of this technique.

METHODS AND RESULTS
From January 1975 to December 1990, 327 patients underwent mitral valve repair with the Duran flexible ring annuloplasty for rheumatic valve disease. Mean age was 45.4 +/- 12.6 years (range, 23 to 73 years). The techniques used for valve repair include a Duran flexible ring annuloplasty in all cases, commissurotomy in 272 (83.2%), papillary muscle splitting in 171 (52.3%), and subvalvular apparatus repair in 59 patients (18.0%). One hundred one patients required associated tricuspid valve surgery (30.8%). Hospital mortality was 3.36%, being lower for patients with isolated mitral valve repair (2.7%) than those with mitrotricuspid surgery (4.9%). Mean follow-up was 8.6 years (range, 1 to 17 years) and was 96.5% completed. Thirty-four patients required reoperation for severe mitral insufficiency in 12, mitral restenosis in 18, and aortic valve disease in 4. The actuarial curve free from reoperation for mitral cause at 16 years is 89.9 +/- 3.2%. Late mortality occurred in 42 patients (13.2%). Actuarial survival curve at 16 years is 84.0 +/- 3.2% for isolated mitral valve repair and 64.6 +/- 6.7% for mitrotricuspid patients.

CONCLUSIONS
Mitral valve reconstruction with Duran flexible ring annuloplasty in rheumatic valve disease entails a low hospital mortality with satisfactory long-term clinical results.
Acute effect of percutaneous transvenous mitral commissurotomy on ventilatory and hemodynamic responses to exercise. Pathophysiological basis for early symptomatic improvement.
Authors: Tanabe Y , Suzuki M , Takahashi M , Oshima M , Yamazaki Y , Yamaguchi T , Igarashi Y , Tamura Y , Yamazoe M , Shibata A 
Published: June 2012

BACKGROUND
Improvement of exertional dyspnea occurs immediately after percutaneous transvenous mitral commissurotomy (PTMC), but the pathophysiological basis for this early symptomatic improvement has not been elucidated.

METHODS AND RESULTS
Exercise hemodynamic measurement and exercise ventilatory measurement with arterial blood gas analysis were performed in 21 patients aged 50.4 +/- 9.5 years (mean +/- SD) with symptomatic mitral stenosis before and a few days after PTMC. Exercise ventilatory measurement were also performed in 14 normal control subjects aged 48.9 +/- 4.9 years. After PTMC, mitral valve area increased (from 1.0 +/- 0.3 to 1.7 +/- 0.3 cm2, P < .001), mean mitral gradient (from 12.2 +/- 5.2 to 5.2 +/- 2.2 mm Hg, P < .001), and mean left atrial pressure (from 18.7 +/- 6.1 to 12.1 +/- 4.0 mm Hg, P < .001) decreased. All patients experienced significant symptomatic improvement soon after PTMC. Comparison of hemodynamic parameters at the same ergometer work rate showed a significant decrease in pulmonary artery systolic pressure (from 77 +/- 18 to 67 +/- 14 mm Hg, P < .001) and diastolic pressure (from 36 +/- 10 to 28 +/- 7 mm Hg, P < .001) and a significant increase in cardiac output (from 6.4 +/- 1.4 to 8.1 +/- 1.9 L/min, P < .001). Despite the improvement in exercise hemodynamics and symptoms, exercise capacity determined by peak oxygen uptake (from 18.0 +/- 2.9 to 18.6 +/- 3.1 mL.kg-1 x min-1) and anaerobic threshold (from 11.7 +/- 2.4 to 12.0 +/- 2.4 mL.kg-1 x min-1) remained unchanged. Excessive exercise ventilation, as assessed by the slope of the regression line between expired minute ventilation and carbon dioxide output, decreased significantly from 37.2 +/- 6.7 to 33.9 +/- 5.8 (P < .001), but remained significantly higher than that in the normal subjects (27.9 +/- 3.6, P < .01). The ratio of total dead space to tidal volume and total dead space per breath during exercise decreased significantly after PTMC (P < .05). The change in excessive exercise ventilation after PTMC was correlated with the change in dead space to tidal volume ratio (r = .59).

CONCLUSIONS
Significant relief of exertional dyspnea immediately after PTMC is not accompanied by an improvement in exercise capacity. A decrease in excessive ventilation due to a decrease in physiological dead space resulting from hemodynamic improvement partly contributes to the early relief of symptoms after PTMC. However, lung compliance, which was not measured in the present study, may have changed after PTMC. This change may also contribute to the symptomatic improvement.
Bystander cardiopulmonary resuscitation. Is ventilation necessary?
Authors: Berg R A , Kern K B , Sanders A B , Otto C W , Hilwig R W , Ewy G A 
Published: June 2012

BACKGROUND
Prompt initiation of bystander cardiopulmonary resuscitation (CPR) improves survival. Basic life support with mouth-to-mouth ventilation and chest compressions is intimidating, difficult to remember, and difficult to perform. Chest compressions alone can be easily taught, easily remembered, easily performed, adequately taught by dispatcher-delivered telephone instruction, and more readily accepted by the public. The principal objective of this study was to evaluate the need for ventilation during CPR in a clinically relevant swine model of prehospital witnessed cardiac arrest.

METHODS AND RESULTS
Thirty seconds after ventricular fibrillation, swine were randomly assigned to 12 minutes of chest compressions plus mechanical ventilation (group A), chest compressions only (group B), or no CPR (group C). Standard advanced cardiac life support was then provided. Animals successfully resuscitated were supported for 2 hours in an intensive care setting, and then observed for 24 hours. All 16 swine in groups A and B were successfully resuscitated and neurologically normal at 24 hours, whereas only 2 of 8 group C animals survived for 24 hours (P < .001, Fisher's exact test). One of the 2 group C survivors was comatose and unresponsive.

CONCLUSIONS
In this swine model of witnessed prehospital cardiac arrest, the survival and neurological outcome data establish that prompt initiation of chest compressions alone appears to be as effective as chest compressions plus ventilation and that both techniques of bystander CPR markedly improve outcome compared with no bystander CPR.
Serotonin-induced coronary spasm in a swine model. A minor role of defective endothelium-derived relaxing factor.
Authors: Fukai T , Egashira K , Hata H , Numaguchi K , Ohara Y , Takahashi T , Tomoike H , Takeshita A 
Published: June 2012

BACKGROUND
Coronary spasm may be caused by endothelial dysfunction, vascular smooth muscle hyperreactivity, or both. We aimed to determine the relative role of endothelial dysfunction and vascular smooth muscle hyperreactivity in the pathogenesis of coronary artery spasm in the swine model in vivo.

METHODS AND RESULTS
In Göttingen miniature pigs given a high cholesterol diet, a segment of the left coronary artery was denuded and irradiated with x-ray (total, 30 Gy). Three months after endothelial denudation and irradiation, vasomotor responses of the denuded and control sites to agonists were assessed by quantitative arteriography. Serotonin (10 micrograms/kg) provoked coronary spasm at the denuded site (diameter reduction, 79 +/- 6%) associated with ST elevation but not at the nondenuded control site (21 +/- 6%). Intracoronary infusion of N omega-nitro-L-arginine methyl ester (LNNA, an inhibitor of endothelium-derived nitric oxide) of 1 and 3 mg/kg potentiated constriction evoked with serotonin (1, 3, 10 micrograms/kg) at the control site but did not alter it at the denuded site. However, serotonin-induced constriction after LNNA was still less at the control site (31 +/- 3%) than at the denuded site (80 +/- 5%). Endothelium-dependent vasodilation with substance P (0.1, 1, 10 ng/kg), which was inhibited by LNNA, was less (P < .01) at the denuded site than at the control site, whereas vasodilation with the nitrovasodilator SIN-1 (0.1, 1, 10 ng/kg) was comparable between the two sites. Histological study revealed regenerated endothelial cells and intimal thickening at the denuded site.

CONCLUSIONS
The results suggest that the denuded segment of the coronary artery with regenerated endothelium was associated with defective endothelium-dependent vasodilation mediated by nitric oxide and vascular smooth muscle hyperreactivity to serotonin. However, provocation of coronary spasm with serotonin resulted primarily from vascular smooth muscle hyperreactivity but not by defective nitric oxide production in this swine model.
Hyperbaric oxygen limits infarct size in ischemic rabbit myocardium in vivo.
Authors: Sterling D L , Thornton J D , Swafford A , Gottlieb S F , Bishop S P , Stanley A W , Downey J M 
Published: June 2012

BACKGROUND
We explored the ability of increased oxygen pressure to modify necrosis in an open-chest rabbit model of myocardial ischemia and reperfusion.

METHODS AND RESULTS
A branch of the left coronary artery was occluded for 30 minutes followed by 3 hours of reperfusion. Infarction was measured by triphenyl tetrazolium staining and expressed as a percentage of the ischemic zone. Untreated rabbits were ventilated with 100% oxygen at 1 atm absolute. Treatment animals were exposed to hyperbaric oxygen at 2.5 atm absolute. The 1.0-atm control hearts developed 41.5 +/- 4.6% infarction of the ischemic zone. Animals exposed to hyperbaric oxygen during ischemia only, reperfusion only, or ischemia and reperfusion had significantly smaller infarcts with respect to control animals (16.2 +/- 2.9%, 14.5 +/- 3.7%, and 9.8 +/- 2.7%, respectively; P < or = .01), indicating that they had been protected by the procedure. When hyperbaric oxygen was begun 30 minutes after the onset of reperfusion, no protection was seen (35.8 +/- 3.8%).

CONCLUSIONS
We conclude that hyperbaric oxygen limits infarct size in the reperfused rabbit heart and that the effect can be achieved when hyperbaric oxygen is begun at reperfusion.
Aspirin versus heparin to prevent myocardial infarction during the acute phase of unstable angina.
Authors: Théroux P , Waters D , Qiu S , McCans J , de Guise P , Juneau M 
Published: June 2012

BACKGROUND
Antiplatelet therapy with aspirin and antithrombotic therapy with heparin both prevent the complications of unstable angina; however, no definitive data exist on the relative clinical efficacy of the two drugs.

METHODS AND RESULTS
Aspirin (325 mg bid) or heparin (5000-U intravenous bolus followed by a perfusion titrated to the APTT) were compared in a double-blind randomized trial of 484 patients in two cohorts enrolled sequentially. The study was initiated at admission to hospital at a mean of 8.3 +/- 7.8 hours after the last episode of pain. End points were assessed 5.7 +/- 3.3 days later, when the decision for long-term management was made. Myocardial infarction occurred in 2 (0.8%) of the 240 patients randomized to heparin and in 9 (3.7%) of the 244 randomized to aspirin (P = .035), an odds ratio of 0.22 and a risk difference of 2.9% (95% confidence limits, 0.3% to 5.6%) with heparin. The only death resulted from a myocardial infarction in an aspirin patient. Survival curves with Cox logistic regression analysis showed that the improvement in survival without myocardial infarction with heparin (P = .035) was independent of other baseline characteristics.

CONCLUSIONS
This study documents that heparin prevents myocardial infarction better than aspirin during the acute phase of unstable angina.
Thromboxane A2 and prostacyclin biosynthesis in children and adolescents with pulmonary vascular disease.
Authors: Adatia I , Barrow S E , Stratton P D , Miall-Allen V M , Ritter J M , Haworth S G 
Published: June 2012

BACKGROUND
The pathogenesis of pulmonary vascular disease in children with congenital heart disease is incompletely understood. Thromboxane (TX) A2 and prostacyclin (PGI2) have opposing effects on platelet aggregation and pulmonary vascular smooth muscle. An imbalance in their biosynthesis could contribute to the progressive increase in pulmonary vascular resistance seen in older untreated patients with pulmonary hypertensive congenital heart disease and the thrombotic complications they may develop.

METHODS AND RESULTS
We investigated TXA2 and PGI2 biosynthesis in 15 young children (0.2 to 2.25 years old) with congenital heart disease with increased pulmonary blood flow and potentially reversible pulmonary vascular disease by measuring urinary excretion of 2,3-dinor-TXB2 and 2,3-dinor-6-oxoprostaglandin (PG) F1 alpha and compared the findings with those in 16 healthy children (0.5 to 2.8 years old). 2,3-Dinor-TXB2 excretion was greater in the patients than in control subjects (1253 +/- 161 versus 592 +/- 122 ng/g creatinine; P < .001). Excretion of 2,3-dinor-6-oxo-PGF1 alpha was 452 +/- 54 compared with 589 +/- 95 ng/g creatinine in control subjects. In 5 patients who underwent successful cardiac surgery > or = 1 year later excretion of 2,3-dinor-TXB2 decreased from 1100 +/- 298 to 609 +/- 131 ng/g creatinine (P < .05), a value comparable to those in 5 healthy children of similar age (749 +/- 226 ng/g creatinine). We also compared 15 patients (11 to 23 years old) with advanced irreversible pulmonary vascular disease with 19 healthy control subjects (10 to 23 years old). The ratio of TX to PGI2 metabolite excretion was greater in the patients than in control subjects (3.5 +/- 0.6 versus 2.0 +/- 0.3; P < .05).

CONCLUSIONS
There is increased 2,3-dinor-TXB2 excretion in children with congenital heart disease and a high pulmonary blood flow that may reflect an imbalance in biosynthesis of TXA2 and PGI2 in the pulmonary vascular bed. The imbalance may contribute to the progressive development of increased pulmonary vascular resistance and persists in older patients whose heart defects are uncorrected.