ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundStandard mapping and ablation of focal sources of atrial fibrillation are associated with very long procedure times and low efficacy. An anatomic approach to complete pulmonary vein isolation could overcome these limitations.Methods and ResultsFifteen patients with atrial fibrillation refractory to medication underwent circumferential isolation of the pulmonary veins by using a novel catheter, with an ultrasound transducer (8-MHz) mounted near the tip, in a saline-filled balloon. Twelve atrial foci and/or atrial fibrillation triggers were identified in 9 patients (pulmonary vein locations: left upper, 3; right upper, 6; right middle, 1; right lower, 1; and left inferior, 1). In 5 patients, lesions were placed in the absence of any mapped triggers. Irrespective of trigger mapping, circumferential isolation of both upper pulmonary veins was attempted in all patients. The lower pulmonary veins were ablated when sinus rhythm activation mapping revealed evidence of a sleeve of atrial muscle in the vein. The median number of lesions per patient required to isolate 1 pulmonary vein was 4 (range, 1 to 29). After ablation, no evidence of narrowing was seen with repeat venography or follow-up computed tomography scan. After a mean follow-up of 35±6 weeks, 5 patients had recurrence of atrial fibrillation. Three responded to drugs that were previously ineffective, and 2 remained in atrial fibrillation.ConclusionsThis novel ultrasound ablation system can successfully isolate multiple pulmonary veins. At early follow-up, this approach seems to be effective in preventing recurrent atrial fibrillation in a significant number of patients.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundSeveral cases of QT prolongation and ventricular tachyarrhythmia have been reported with domperidone, a gastrokinetic and antiemetic agent available worldwide but still under investigation in the United States. Although electrolyte disturbances such as hypokalemia could account for some of these events, we hypothesized that domperidone may have unsuspected electrophysiological effects predisposing some patients to proarrhythmia.Methods and ResultsStudies were undertaken in 9 isolated guinea pig hearts, which demonstrated reverse use–dependent prolongation of cardiac repolarization by 100 nmol/L domperidone. Action potential duration increased 27% from baseline with domperidone (from 114±3 to 145±2 ms) during pacing at a cycle length of 250 ms, and a 9% increase (from 97±2 to 106±3 ms) was seen with pacing at a cycle length of 150 ms. Experiments in human ether-a-go-go–related gene (HERG)-transfected Chinese hamster ovary cells (n=32) demonstrated a concentration-dependent block of the rapid component (IKr) of the delayed rectifier potassium current. The tail current decreased by 50% at 162 nmol/L domperidone.ConclusionsDomperidone possesses cardiac electrophysiological effects similar to those of cisapride and class III antiarrhythmic drugs. These effects are observed at clinically relevant concentrations of the drug. Therefore, domperidone should not be considered a no-risk alternative to cisapride, a drug that was recently withdrawn from the US market.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundPlasma triglyceride concentration has been an inconsistent independent risk factor for coronary heart disease, perhaps because of the metabolic heterogeneity among VLDL particles, the main carriers of triglycerides in plasma.Methods and ResultsWe conducted a prospective, nested case-control study in the Cholesterol and Recurrent Events (CARE) trial, a randomized placebo-controlled trial of pravastatin in 4159 patients with myocardial infarction and average LDL concentrations at baseline (115 to 174 mg/dL, mean 139 mg/dL). Baseline concentrations of VLDL–apolipoprotein (apo) B (the VLDL particle concentration), VLDL lipids, and apoCIII and apoE in VLDL+LDL and in HDL were compared in patients who had either a myocardial infarction or coronary death (cases, n=418) with those in patients who did not have a cardiovascular event (control subjects, n=370) in 5 years of follow-up. VLDL-cholesterol, VLDL-triglyceride, VLDL-apoB, apoCIII and apoE in VLDL+LDL and apoE in HDL were all interrelated, and each was a univariate predictor of subsequent coronary events. The significant independent predictors were VLDL-apoB (relative risk [RR] 3.2 for highest to lowest quintiles,P=0.04), apoCIII in VLDL+LDL (RR 2.3,P=0.04), and apoE in HDL (RR 1.8,P=0.02). Plasma triglycerides, a univariate predictor of coronary events (RR 1.6,P=0.03), was not related to coronary events (RR 1.3,P=0.6) when apoCIII in VLDL+LDL was included in the model, whereas apoCIII remained significant. Adjustment for LDL- and HDL-cholesterol did not affect these results.ConclusionsThe plasma concentrations of VLDL particles and apoCIII in VLDL and LDL are more specific measures of coronary heart disease risk than plasma triglycerides perhaps because their known metabolic properties link them more closely to atherosclerosis.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundPrevious trials have had insufficient numbers of coronary events to address definitively the effect of lipid-modifying therapy on coronary heart disease in subgroups of patients with varying baseline characteristics.Methods and ResultsThe data from 3 large randomized trials with pravastatin 40 mg were pooled and analyzed with the use of a prospectively defined protocol. Included were 19 768 patients, 102 559 person-years of follow-up, 2194 primary end points (coronary death or nonfatal myocardial infarction), and 3717 expanded end points (primary end point, CABG, or PTCA). Pravastatin significantly reduced relative risk in younger (<65 years) and older (≥65 years) patients, men and women, smokers and nonsmokers, and patients with or without diabetes or hypertension. The relative effect was smaller, but absolute risk reduction was similar in patients with hypertension compared with those without hypertension. Relative risk reduction was significant in predefined categories of baseline lipid concentrations. Tests for interaction were not significant between relative risk reduction and baseline total cholesterol (5% to 95% range 177 to 297 mg/dL, 4.6 to 7.7 mmol/L), HDL cholesterol (27 to 58 mg/dL, 0.7 to 1.5 mmol/L), and triglyceride (74 to 302 mg/dL, 0.8 to 3.4 mmol/L) concentrations, analyzed as continuous variables. However, for LDL cholesterol, the probability values for interaction were 0.068 for the prespecified primary end point and 0.019 for the expanded end point. Relative risk reduction was similar throughout most of the baseline LDL cholesterol range (125 to 212 mg/dL, 3.2 to 5.5 mmol/L) with the possible exception of the lowest quintile of CARE/LIPID (<125 mg/dL) (relative risk reduction 5%, 95% CI 19% to −12%).ConclusionsPravastatin treatment is effective in reducing coronary heart disease events in patients with high or low risk factor status and across a wide range of pretreatment lipid concentrations.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundThe major platelet integrin glycoprotein IIb-IIIa plays a primary role in platelet aggregation and acute thrombus formation at the site of vascular injury. A genetic polymorphism of glycoprotein IIb-IIIa (PlA) has recently been proposed as a potential genetic factor linking to platelet hyperaggregability and increased risk of myocardial infarction. Despite numerous, mostly nonprospective studies, the role of this polymorphism as a clinically relevant, inherited risk factor for coronary heart disease (CHD) is still controversial. The purpose of this study was to determine whether PlA2is a risk factor for incident CHD and whether it is correlated with increased platelet activation in a case-cohort study nested within a prospective epidemiologic investigation.Methods and ResultsBlood samples were collected and processed from the Atherosclerosis Risk in Communities Study cohort at the baseline examination (1987 to 1989). They were stored at −80°C. PlA1/A2genotype and plasma &bgr;-thromboglobulin levels were determined in 439 incident CHD cases and a reference cohort sample of 544 (of whom 18 were also CHD cases). The prevalence of the PlA2allele was not different in cases versus noncases. No significant correlation between CHD risk factors and the PlA2allele was noted either. Platelet activation, as measured by plasma &bgr;-thromboglobulin levels, was not enhanced in individuals with the PlA2allele.ConclusionsThis prospective study indicates that healthy individuals carrying the PlA2allele do not have an increased risk of CHD.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

BackgroundExperimental studies suggest that androgens induce coronary vasodilatation. We performed this pilot project to examine the clinical effects of long-term low-dose androgens in men with angina.Methods and ResultsForty-six men with stable angina completed a 2-week, single-blind placebo run-in, followed by double-blind randomization to 5 mg testosterone daily by transdermal patch or matching placebo for 12 weeks, in addition to their current medication. Time to 1-mm ST-segment depression on treadmill exercise testing and hormone levels were measured and quality of life was assessed by SF-36 at baseline and after 4 and 12 weeks of treatment. Active treatment resulted in a 2-fold increase in androgen levels and an increase in time to 1-mm ST-segment depression from (mean±SEM) 309±27 seconds at baseline to 343±26 seconds after 4 weeks and to 361±22 seconds after 12 weeks. This change was statistically significant compared with that seen in the placebo group (from 266±25 seconds at baseline to 284±23 seconds after 4 weeks and to 292±24 seconds after 12 weeks;P=0.02 between the 2 groups by ANCOVA). The magnitude of the response was greater in those with lower baseline levels of bioavailable testosterone (r=−0.455,P<0.05). There were no significant changes in prostate specific antigen, hemoglobin, lipids, or coagulation profiles during the study. There were significant improvements in pain perception (P=0.026) and role limitation resulting from physical problems (P=0.024) in the testosterone-treated group.ConclusionsLow-dose supplemental testosterone treatment in men with chronic stable angina reduces exercise-induced myocardial ischemia.

ISSN:0009-7322    

出版商:OVID    

年代:2000

数据来源: OVID