ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundCatheter ablation of typical right atrial flutter is now widely performed. The best end point has been demonstrated to be bidirectional isthmus block. We investigated the use of irrigated-tip catheters in a small subset of patients who failed isthmus ablation with conventional radiofrequency (RF) ablation.21 applications failed to create a bidirectional block in 13 (7.6%). An irrigated-tip catheter ablation was performed on identified gaps in the ablation line according to a protocol found to be safe in animals: a moderate flow rate of 17 mL/min and temperature-controlled (target, 50[degree sign]C) RF delivery with a power limit of 50 W. Bidirectional isthmus block was achieved in 12 patients by use of a mean delivered power of 40 +/- 6 W with a single application in 6 patients and 2 to 6 applications in the other 6. No side effects occurred during or after the procedure.ConclusionsIrrigated-tip catheter ablation is safe and effective for achieving cavotricuspid isthmus block when conventional RF energy has failed. (Circulation. 1998;98:835-838.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundWe studied whether inflammation after myocardial infarction (MI) is a risk factor for recurrent coronary events and whether randomized treatment with pravastatin reduces that risk.Methods and Results-A nested case-control design was used to compare C-reactive protein (CRP) and serum amyloid A (SAA) levels in prerandomization blood samples from 391 participants in the Cholesterol and Recurrent Events (CARE) trial who subsequently developed recurrent nonfatal MI or a fatal coronary event (cases) and from an equal number of age- and sex-matched participants who remained free of these events during follow-up (control subjects). Overall, CRP and SAA were higher among cases than control subjects (for CRP P=0.05; for SAA P=0.006) such that those with levels in the highest quintile had a relative risk (RR) of recurrent events 75% higher than those with levels in the lowest quintile (for CRP RR=1.77, P=0.02; for SAA RR=1.74, P=0.02). The study group with the highest risk was that with consistent evidence of inflammation (elevation of both CRP and SAA) who were randomly assigned to placebo (RR=2.81, P=0.007); this risk estimate was greater than the product of the individual risks associated with inflammation or placebo assignment alone. In stratified analyses, the association between inflammation and risk was significant among those randomized to placebo (RR=2.11, P=0.048) but was attenuated and nonsignificant among those randomized to pravastatin (RR=1.29, P=0.5).ConclusionsEvidence of inflammation after MI is associated with increased risk of recurrent coronary events. Therapy with pravastatin may decrease this risk, an observation consistent with a nonlipid effect of this agent. (Circulation. 1998;98:839-844.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundSeveral epidemiological and clinical reports have suggested seropositivity for Helicobacter pylori may be a risk factor for coronary heart disease. However, there has been no prospective study of this association involving an ethnically diverse sample of middle-aged men and women.Methods and Results-Using a prospective, case-cohort design, we determined H pylori seropositivity in relation to coronary heart disease incidence over a median follow-up period of 3.3 years among middle-aged men and women. There were 217 incident coronary heart disease cases and a cohort sample of 498. We determined H pylori antibody status by measuring IgG antibody to the high-molecular-weight cell-associated proteins of H pylori using a sensitive and specific ELISA. The prevalence of H pylori seropositivity was higher in blacks than whites, in those with less than high school education, in those with lower plasma pyridoxal 5[prime]-phosphate and higher homocyst(e)ine concentrations, in those who did not use vitamin supplements, in those with higher fibrinogen levels, and in those seropositive for cytomegalovirus and herpes simplex type I (all P<0.05). The age-, sex-, race-, and field center-adjusted hazard ratio of coronary heart disease for H pylori seropositivity was 1.03 (95% CI=0.68 to 1.57). After adjustment for other risk factors, including fibrinogen, cytomegalovirus seropositivity, and herpes simplex type I seropositivity, the hazard ratio was 0.85 (95% CI=0.43 to 1.69). H pylori seropositivity also was not associated with increased mean intima-media thickness of the carotid artery, a measure of subclinical atherosclerosis.ConclusionsH pylori infection is probably not an important contributor to clinical coronary heart disease events. (Circulation. 1998;98:845-850.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundWe sought to determine the frequency with which physicians follow National Cholesterol Education Program (NCEP-ATPII) guidelines in screening for cardiovascular risk factors and treating hyperlipidemia.Methods and Results-We conducted a retrospective chart review on randomly sampled charts of 225 patients admitted to the coronary care unit between January and June 1996. The main outcome measures were rates of physician screening for coronary heart disease risk factors; rates of counseling for cigarette cessation, diet, and exercise; and extent of use of NCEP algorithms for obtaining LDL cholesterol values and treating hypercholesterolemia. Screening rates for interns (who performed best) were: cigarette use (89%), known coronary heart disease (74%), hypertension (68%), hyperlipidemia (59%), family history (56%), diabetes (37%), postmenopausal hormone therapy (11%), and premature menopause (1%). Four percent of smokers were counseled to quit, 14% of patients were referred to dietitians, and 1% were encouraged to exercise. A full lipid panel was obtained in 50% of patients in whom it was indicated on the basis of NCEP criteria. Patients were more likely to receive lipid-lowering treatment if NCEP criteria indicated that they should, but 36% of hospitalized patients and 46% of patients who should have been treated on discharge were not.ConclusionsPhysicians are poorly compliant with NCEP guidelines for risk factor assessment and counseling, even in patients at high risk for coronary heart disease. Physicians follow NCEP-ATPII algorithms for obtaining an LDL value, a key step in evaluating the need for treatment, only 50% of the time. NCEP criteria seem to influence the decision to initiate lipid-lowering therapy, but significant numbers of eligible patients remain untreated. (Circulation. 1998;98:851-855.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundIn hypertrophic cardiomyopathy, a spectrum of mitral leaflet abnormalities has been related to the mechanism of mitral systolic anterior motion (SAM), which causes both subaortic obstruction and mitral regurgitation. In the individual patient, SAM and regurgitation vary in parallel; clinically, however, great interindividual differences in mitral regurgitation can occur for comparable degrees of SAM. We hypothesized that these differences relate to variations in posterior leaflet length and mobility, restricting its ability to follow the anterior leaflet (participate in SAM) and coapt effectively.Methods and Results-Different mitral geometries produced surgically in porcine valves were studied in vitro. Comparable degrees of SAM resulted in more severe mitral regurgitation for geometries characterized by limited posterior leaflet excursion. Mitral geometry was also analyzed in 23 patients with hypertrophic cardiomyopathy by intraoperative transesophageal echocardiography. All had typical anterior leaflet SAM with significant outflow tract gradients but considerably more variable mitral regurgitation; therefore, regurgitation did not correlate with obstruction. In contrast, mitral regurgitation correlated inversely with the length over which the leaflets coapted (r=-0.89), the most severe regurgitation occurring with a visible gap. Regurgitation increased with increasing mismatch of anterior to posterior leaflet length (r=0.77) and decreasing posterior leaflet mobility (r=-0.79).ConclusionsSAM produces greater mitral regurgitation if the posterior leaflet is limited in its ability to move anteriorly, participate in SAM, and coapt effectively. This can explain interindividual differences in regurgitation for comparable degrees of SAM. Thus, the spectrum of leaflet length and mobility that affects subaortic obstruction also influences mitral regurgitation in patients with SAM. (Circulation. 1998;98:856-865.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundNoninvasive assessment of functionally stenotic small-diameter aortic mechanical prostheses is complicated by theoretical constraints relating to the hemodynamic relevance of Doppler-derived transprosthetic gradients. To establish the utility of Doppler echocardiography for evaluation of these valves, 20-mm Medtronic Hall and 19-mm St Jude prostheses were studied in vitro and in vivo.Methods and Results-Relations between the orifice transprosthetic gradient (equivalent to Doppler), the downstream gradient in the zone of recovered pressure (equivalent to catheter), and fluid mechanical energy losses were examined in vitro. Pressure-flow relations across the 2 prostheses were evaluated by Doppler echocardiography in vivo. For both types of prosthesis in vitro, the orifice was higher than the downstream gradient (P<0.001), and fluid mechanical energy losses were as strongly correlated with orifice as with downstream pressure gradients (r2=0.99 for both). Orifice and downstream gradients were higher and fluid mechanical energy losses were larger for the St Jude than the Medtronic Hall valve (all P<0.001). Whereas estimated effective orifice areas for the 2 valves in vivo were not significantly different, model-independent dynamic analysis of pressure-flow relations revealed higher gradients for the St Jude than the Medtronic Hall valve at a given flow rate (P<0.05).ConclusionsEven in the presence of significant pressure recovery, the Doppler-derived gradient across small-diameter aortic mechanical prostheses does have hemodynamic relevance insofar as it reflects myocardial energy expenditure. Small differences in function between stenotic aortic mechanical prostheses, undetectable by conventional orifice area estimations, can be identified by dynamic Doppler echocardiographic analysis of pressure-flow relations. (Circulation. 1998;98:866-872.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundAfter activation, platelets adhere to neutrophils via P-selectin and beta2-integrin. The molecular mechanisms and adhesion events in whole blood exposed to venous levels of hydrodynamic shear in the absence of exogenous activation remain unknown.Methods and Results-Whole blood was sheared at [almost equal to]100 s-1. The kinetics of neutrophil-platelet adhesion and neutrophil aggregation were measured in real time by flow cytometry. P-selectin was upregulated to the platelet surface in response to shear and was the primary factor mediating neutrophil-platelet adhesion. The extent of neutrophil aggregation increased linearly with platelet adhesion to neutrophils. Blocking either P-selectin, its glycoprotein ligand PSGL-1, or both simultaneously by preincubation with a monoclonal antibody resulted in equivalent inhibition of neutrophil-platelet adhesion ([almost equal to]30%) and neutrophil aggregation ([almost equal to]70%). The residual amount of neutrophil adhesion was blocked with anti-CD11b/CD18. Treatment of blood with prostacyclin analogue ZK36374, which raises cAMP levels in platelets, blocked P-selectin upregulation and neutrophil aggregation to baseline. Complete abrogation of platelet-neutrophil adhesion required both ZK36374 and anti-CD18. Electron microscopic observations of fixed blood specimens revealed that platelets augmented neutrophil aggregation both by forming bridges between neutrophils and through contact-mediated activation.ConclusionsThe results are consistent with a model in which venous levels of shear support platelet adherence to neutrophils via P-selectin binding PSGL-1. This interaction alone is sufficient to mediate neutrophil aggregation. Abrogation of platelet adhesion and aggregation requires blocking Mac-1 in addition to PSGL-1 or P-selectin. The described mechanisms are likely of key importance in the pathogenesis and progression of thrombotic disorders that are exacerbated by leukocyte-platelet aggregation. (Circulation. 1998;98:873-882.)

ISSN:0009-7322    

出版商:OVID    

年代:1998

数据来源: OVID