ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background—Late stent malapposition has been reported to be an abnormal finding after vascular brachytherapy and, possibly, implantation of drug-eluting stents. It can only be detected if intravascular ultrasound (IVUS) is performed at follow-up. However, the “background” frequency of late stent malapposition after bare-metal stent implantation is not known.Methods and Results—We studied 206 patients with native artery lesions who had tubular-slotted bare-metal stent implantation and who had IVUS performed at index and after 6±3 months of follow-up. There were 9 patients (4.4%) with late malapposition, which is separation of at least 1 stent strut from the arterial wall intima that does not overlap a side-branch, with evidence of blood flow (speckling) behind the strut, and where the immediate postimplantation IVUS revealed complete apposition of the stent to the vessel wall. The location of late malapposition was the stent edge in 8 of 9 patients. The maximum area, length, volume, and arc of late malapposition measured 3.1±2.4 mm2, 3.3±2.2 mm, 21±27 mm3, and 110±61 degrees, respectively. There was an increase in external elastic membrane (EEM) area (20.7±4.9 to 26.9±4.2 mm,P=0.0021) and plaque area (10.1±3.7 to 14.8±3.6 mm,P=0.0022); however, the increase in EEM was greater than the increase in plaque. The area of late malapposition correlated directly with the increase in EEM area (r=0.75,P=0.0205).Conclusion—Late malapposition occurs in 4% to 5% of slotted-tube bare-metal stents, usually at stent edges. The main cause is positive remodeling out of proportion to the increase in peri-stent intimal hyperplasia.

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background—Manipulating gene expression in the failing heart has therapeutic promise, but until now efficient and homogeneous cardiac gene delivery has required an open-chest approach. This study examines the hypothesis that vector delivery promoted by echo contrast microbubbles will be maximized by injection of the vectors into the aortic root with brief balloon occlusion above the sinuses, while at the same time prolonging diastole and vasodilating with acetylcholine (ACh) to maximize coronary exposure.Methods and Results—After incubation with albumin-coated perfluorocarbon microbubbles, an adenovirus encoding a reporter gene was infused into the aortic root of rats. To maximize delivery, the aortic root was transiently occluded with a balloon catheter during a brief ACh-induced asystole. Ultrasound was used to image the delivery and disrupt the microbubbles. Aortic occlusion with concomitant ACh increased myocardial gene expression for virus + microbubbles by >2.5-fold, from 925±165 to 2358±376 relative units (RU;P<0.01). This delivery system also produced substantial expression with vector alone (1473±549 RU). All uptakes were significant compared with 433±332 RU without virus.Conclusions—An adenoviral delivery system combining echo contrast with a catheter-based technique to maximize coronary perfusion increases gene delivery compared with echo contrast alone. This novel method permits efficient percutaneous gene delivery in closed-chest animals.

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background—Biventricular (BiV) and left ventricular (LV) pacing similarly augment systolic function in left bundle-branch block (LBBB)-failing hearts despite different electrical activation. We tested whether electrical synchrony is required to achieve mechanical synchronization and functional benefit from pacing.Methods and Results—Epicardial mapping, tagged MRI, and hemodynamics were obtained in dogs with LBBB-failing hearts during right atrial, LV, and BiV stimulation. BiV and LV both significantly improved chamber hemodynamics (eg, 25% increase in dP/dtmaxand aortic pulse pressure) compared with atrial pacing-LBBB, and this improvement correlated with mechanical resynchronization. Electrical dispersion, however, decreased 13% with BiV but increased 23% with LV pacing (P<0.01).Conclusion—Improved mechanical synchrony and function do not require electrical synchrony. Mechanical coordination plays the dominant role in global systolic improvement with either pacing approach.

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background—Off-pump coronary artery bypass surgery has been demonstrated to reduce morbidity in elective patients. However, high-risk patients might benefit the most from this surgical procedure. Our goal was to investigate the effectiveness of on-pump and off-pump coronary artery bypass surgery on early clinical outcome in a consecutive series of overweight patients.Methods and Results—From April 1996 to April 2001, data on 4321 patients undergoing coronary surgery (mortality 1.4%) were prospectively entered into the Patient Analysis and Tracking System. Data were extracted for all patients with a body mass index ≥25 kg/m2. A risk-adjusted analysis was performed to assess the effect of surgical technique in the whole overweight cohort. 2844 patients were identified (2261 male, median age 63, interquartile range 56 to 68). Patients undergoing on-pump surgery (2170, 76.3%) were less likely than those undergoing off-pump surgery to have hypercholesterolemia or left main stem disease and were, on average, less obese. However, they were more likely to have unstable angina and to have had a previous myocardial infarction, and they had more extensive coronary disease and received more grafts (allP<0.05). Unadjusted analyses, taking account only of consultant team, showed significant benefits of off-pump surgery in terms of hospital deaths, arrhythmias, inotropic use, use of intra-aortic balloon pump, blood loss, transfusion requirement, postoperative hemoglobin, chest infections, neurological complications, intensive care unit and hospital stay (allP<0.05). After adjustment for confounding prognostic factors, the benefits of off-pump surgery were still significant for death in hospital, transfusion requirement, postoperative hemoglobin, neurological complications, intensive care unit and hospital stay (ORs 0.35 to 0.79,P<0.05).Conclusions—These results suggest that off-pump surgery is safe and effective and is associated with a reduced in-hospital mortality and morbidity in overweight patients when compared with conventional coronary surgery with cardiopulmonary bypass and cardioplegic arrest.

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background—Postmenopausal estrogen replacement therapy (ERT) has an antioxidant effect that opposes the oxidation of LDL particles. Oral ERT-induced increases in plasma triglyceride, however, decrease LDL particle size, which may counteract this antioxidant effect. Because transdermal ERT decreases plasma triglyceride, it may not decrease LDL particle size and may preserve estrogen’s antioxidant effect. The present study investigates whether transdermal ERT can eliminate the adverse effects of oral ERT on the size and oxidative susceptibility of LDL in postmenopausal women.Methods and Results—Postmenopausal women received no treatment (n=12) or were treated with either 0.625 mg oral conjugated equine estrogen daily (n=16) or with transdermal estradiol (50 &mgr;g/d, n=16) for 3 months. Plasma lipids and the diameter of LDL particles were determined. Susceptibility of LDL to oxidation was analyzed by incubation with CuSO4and subsequent measurement of thiobarbituric acid reactive substance (TBARS) concentrations. Oral ERT significantly increased plasma triglyceride and decreased LDL diameter but did not affect LDL-derived TBARS concentrations. In contrast, transdermal ERT significantly decreased the concentrations of plasma triglyceride and LDL-derived TBARS and significantly increased LDL diameter. Estrogen-induced changes in LDL diameter correlated negatively with changes in plasma triglyceride (r=−0.51,P<0.001) and LDL-derived TBARS (r=−0.50,P<0.001).Conclusions—Because transdermal, but not oral ERT, decreases plasma triglyceride and produces larger LDL particles that are resistant to oxidation, the antioxidant effect of estrogen can be preserved.

ISSN:0009-7322    

出版商:OVID    

年代:2002

数据来源: OVID