ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundThe pathogenesis of essential hypertension is still uncertain, but genetic factors and the sympathetic nervous system are likely to be involved. Sympathetic nerve activity and hormonal circulatory control mechanisms, however, are affected by blood pressure itself. Hence, early functional changes are best investigated in normotensive subjects at risk to develop hypertension, such as normotensive offspring of hypertensive parents.Methods and ResultsMuscle sympathetic nerve activity (MSA) was measured in the peroneal nerve of 10 normotensive offspring of parents with essential hypertension and 8 offspring of normotensive parents. Measurements were performed under resting conditions, during a 10-minute period of hypoxia (12.5% Oxygen2/87.5% Nitrogen2), and during a 3-minute mental stress test. The tests were separated by a 30-minute resting period. Plasma samples for determination of norepinephrine and endothelin were collected before and after the tests. Baseline values of MSA were comparable in offspring of hypertensive and normotensive parents. During hypoxia, MSA, heart rate, and norepinephrine and endothelin plasma levels increased in offspring of hypertensive and normotensive parents to a comparable degree, whereas no significant changes in blood pressure and plasma norepinephrine levels were observed in either group. During mental stress, MSA and plasma norepinephrine and endothelin increased only in offspring of hypertensive parents (P < .001 to .01). In parallel, blood pressure increased significantly only in offspring of hypertensive parents (P < .001 to .05), but heart rate increased in both groups (P < .001 to .05).ConclusionsThe activity of the sympathetic nervous system and plasma norepinephrine and endothelin levels are increased during mental stress only in offspring of hypertensive parents, whereas the response to hypoxia was similar in offspring of hypertensive and normotensive parents, suggesting a genetically determined abnormal regulation of the sympathetic nervous system to certain stressful stimuli in offspring of hypertensive parents. This may play a role in the pathogenesis of essential hypertension. (Circulation. 1996;93:866-869.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundAlthough intravenous heparin is commonly used after thrombolytic therapy, few reports have addressed the relationship between the degree of anticoagulation and clinical outcomes. We examined the activated partial thromboplastin time (aPTT) in 29 656 patients in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) trial and analyzed the relationship between the aPTT and both baseline patient characteristics and clinical outcomes.Methods and ResultsIntravenous heparin was administered as a 5000-U bolus followed by an initial infusion of 1000 U/h, with dose adjustment to achieve a target aPTT of 60 to 85 seconds. aPTTs were collected 6, 12, and 24 hours after thrombolytic administration. Higher aPTT at 24 hours was strongly related to lower patient weight (P < .00001) as well as older age, female sex, and lack of cigarette smoking (all P < .0001). At 12 hours, the aPTT associated with the lowest 30-day mortality, stroke, and bleeding rates was 50 to 70 seconds. There was an unexpected direct relationship between the aPTT and the risk of subsequent reinfarction. There was a clustering of reinfarction in the first 10 hours after discontinuation of intravenous heparin.ConclusionsAlthough the relationship between aPTT and clinical outcome was confounded to some degree by the influence of baseline prognostic characteristics, aPTTs higher than 70 seconds were found to be associated with higher likelihood of mortality, stroke, bleeding, and reinfarction. These findings suggest that until proven otherwise, we should consider the aPTT range of 50 to 70 seconds as optimal with intravenous heparin after thrombolytic therapy. (Circulation. 1996;93:870-878.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundAlthough the Thrombolysis in Myocardial Infarction (TIMI) flow grade is a valuable and widely used qualitative measure in angiographic trials, it is limited by its subjective and categorical nature.Methods and ResultsIn normal patients and patients with acute myocardial infarction (MI) (TIMI 4), the number of cineframes needed for dye to reach standardized distal landmarks was counted to objectively assess an index of coronary blood flow as a continuous variable. The TIMI frame-counting method was reproducible (mean absolute difference between two injections, 4.7 plus/minus 3.9 frames, n = 85). In 78 consecutive normal arteries, the left anterior descending coronary artery (LAD) TIMI frame count (36.2 plus/minus 2.6 frames) was 1.7 times longer than the mean of the right coronary artery (20.4 plus/minus 3.0) and circumflex counts (22.2 plus/minus 4.1, P < .001 for either versus LAD). Therefore, the longer LAD frame counts were corrected by dividing by 1.7 to derive the corrected TIMI frame count (CTFC). The mean CTFC in culprit arteries 90 minutes after thrombolytic administration followed a continuous unimodal distribution (there were not subpopulations of slow and fast flow) with a mean value of 39.2 plus/minus 20.0 frames, which improved to 31.7 plus/minus 12.9 frames by 18 to 36 hours (P < .001). No correlation existed between improvements in CTFCs and changes in minimum lumen diameter (r = -.05, P = .59). The mean 90-minute CTFC among nonculprit arteries (25.5 plus/minus 9.8) was significantly higher (flow was slower) compared with arteries with normal flow in the absence of acute MI (21.0 plus/minus 3.1, P < .001) but improved to that of normal arteries by 1 day after thrombolysis (21.7 plus/minus 7.1, P = NS).ConclusionsThe CTFC is a simple, reproducible, objective, and quantitative index of coronary flow that allows standardization of TIMI flow grades and facilitates comparisons of angiographic end points between trials. Disordered resistance vessel function may account in part for reductions in flow in the early hours after thrombolysis. (Circulation. 1996;93:879-888.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundExperimental studies suggest that mural thrombus may be involved in postangioplasty restenosis. The aim of our study was to examine the role of angiographically identifiable thrombus in the clinical situation.Methods and Results50% diameter stenosis at follow-up) and a continuous approach (absolute and relative losses). The study population included 160 lesions with and 3423 lesions without angiographically identifiable thrombus. The categorical restenosis rate was significantly higher in lesions containing angiographically identifiable thrombus: 43.1% versus 34.4%, P < .01; relative risk, 1.449; CI, 1.051 to 1.997. The absolute and relative losses were also higher in lesions containing angiographically identifiable thrombus (absolute loss, 0.43 plus/minus 0.66 versus 0.32 plus/minus 0.52; relative loss, 0.16 plus/minus 0.26 versus 0.13 plus/minus 0.21; both P < .05). The higher restenosis in these lesions was due primarily to an increased incidence of occlusion at follow-up angiography in this group: 13.8% versus 5.7%, P < .001. When lesions that went on to occlude by the time of follow-up angiography were excluded from the analysis, the restenosis rate between the two groups was similar by both the categorical (34.1% versus 30.4%, P = NS; relative risk, 1.183; CI, 0.824 to 1.696) and continuous (absolute loss, 0.23 plus/minus 0.46 versus 0.24 plus/minus 0.42, P = NS; relative loss, 0.09 plus/minus 0.17 versus 0.09 plus/minus 0.16, P = NS) approaches.ConclusionsOur results indicate that the presence of angiographically identifiable thrombus at the time of the angioplasty procedure is associated with higher restenosis. The mechanism by which this occurs is through vessel occlusion at follow-up angiography. Measures aimed at improving outcome in this group of patients should be focused in this direction. (Circulation. 1996;93:889-897.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID