Revascularization for Renal-Artery Stenosis Staub, Daniel; Uthoff, Heiko; Jaeger, Kurt A
The New England journal of medicine,
02/2010, Letnik:
362, Številka:
8
Journal Article
Recenzirano
To the Editor:
The ASTRAL (Angioplasty and Stenting for Renal Artery Lesions) Investigators (Nov. 12 issue)
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found substantial risk but no clinical benefit from revascularization as compared with ...medical management in patients with atherosclerotic renovascular disease. A total of 806 patients at 57 hospitals were enrolled over the course of 7 years. On average, 2 patients per center per year underwent randomization, which indicates serious selection bias or inexperienced staff at centers with very low intervention rates. This concern is supported by a low rate of technical success (317 of 403 patients 79% in the revascularization group) and a high . . .
Background: The coronary vasodilator reserve with dipyridamole may be impaired immediately after successful angioplasty due to reduced endothelial production or release of nitric oxide. As the ...vasodilator response to exogenous nitrates is enhanced by endothelium removal or inhibition of nitric oxide synthesis, an increased vasodilator response to nitrovasodilators, such as nitroprusside, should occur. Methods: The coronary vasodilator reserve (maximal/basal coronary blood flow) with intravenous dipyridamole (0.56 mg/min for 4 min) was measured by Doppler catheterization before and after angioplasty in 10 patients with single-vessel coronary disease. At peak dipyridamole effect, incremental doses of nitroprusside (4–50 μg/min) were given intracoronary until systolic blood pressure fell by ≥ 5 mmHg. Results: Before angioplasty, the coronary blood flow increased from 19.7 ± 6.1 (mean ± s.d.) at basal to 30.1 ± 11.9 ml/min at the peak dipyridamole effect (P < 0.01), giving a coronary vasodilator reserve of 1.62 ± 0.39 (range 1.20–1.96). After angioplasty, the coronary blood flow increased from 32.4 ± 13.2 at basal to 53.4 ± 23.3 ml/min at the peak dipyridamole effect (P < 0.01), giving a coronary vasodilator reserve of 1.77 ± 0.64 (range 1.17–2.42). Sodium nitroprusside had no additional effect on coronary flow (49.5 ± 20.4 and 52.2 ± 18.0 ml/min) before and after a fall in systolic blood pressure, respectively. Conclusions: The vasodilator response to dipyridamole was markedly impaired immediately after successful angioplasty, and was not augmented by intracoronary nitroprusside. Thus, a reduced production or release of nitric oxide in the coronary circulation does not seem to be responsible for the impaired vasodilator response after angioplasty.
We tested the ability of ultrasound radiofrequency (RF) signal analysis to characterize thrombus accumulation in a Dacron graft incorporated into the exteriorized arteriovenous shunt in 3 baboons ...with constant blood flow for 60 min. Thrombus formation was quantified by sequential measurements of
111Indium-labeled platelet deposition. RF signals were acquired every 15 min at 2 sites in the graft, using a 2.9 Fr intravascular ultrasound catheter-based transducer (30 MHz) and digitized at 250 MHz in 8-bit resolution. Regions of interest were placed within a 0.5-mm perimeter adjacent to the graft wall. Integrated backscatter increased significantly (
p < 0.001) with increasing platelet deposition. However, mean-to–standard deviation ratio of the RF envelope showed no significant change and the distribution pattern of the RF probability function remained constant and consistent with a Rayleigh scattering process. These results provide a basis for using RF analysis to monitor the time-course of thrombus formation.
Objectives. This study was conducted to determine the myocardial beta-adrenoceptor density as a market of sympathetic function in patients with hypertrophic cardiomyopathy and normal control ...subjects.
Bachground. Although some casesof hypertrophic cardiomyopthy are familial with an autosomal dominant pattern of inheritance, there remains a subtatial proportion of cases in which neither a family history nor genetic abnormalities can be demonstrated. Additional abnormalities, both genetic and acquired, may be important in the phenotypic expression of this condition. Clinical features of the ddisease and metabolic studies suggest an increased activity of the sympathetic nervous system.
Methods. Eleven patients with hypertrophic cardiomyopathy, none of whom had previously received beta-blocking drugs, and eight normal control subjects underwent positron emission tomography to evaluate regional left ventricular beta-adrenoceptor density and myocardial blood flow using carbon-11-labeled CGP 12177 and oxygen-15-labeled water as tracers. Plasma catecholamines were also measured.
Results. Mean (±SD) myocardial beta-adrenoceptor density was significantly less in the hypertrophic cardiomyopathy group than in the control group (7.70 ± 1.86 vs. 11.50 ± 2.18 pmol/g tissue, p < 0.001). Myocardial blood flow was similar in both group (0.91 ± 0.22 vs. 0.91 ± 0.21 ml/min per g, p = NS). The distribution of beta-adrenoceptor density was uniform throughout the left ventricle in both groups. In the hypertrophic cardiomyopathy group, there was no correlation between regional wall thickness and myocardial beta-adrenoceptor density. There were no significant differences in either plasma norepinephrine or epinephrine concentrations between the two groups.
Conclusions. There is a diffuse reduction in myocardial betaadrenoceptor density in patients with hypertrophic cardiomyopathy in the absence of significantly elevated circulating catechlamine concentrations. This most likely reflects downregutation of myocardial beta-adrenoceptors secondary to increased myocardial concentrations of norepinephrine and is consistent with the hypothesis that cardiac sympathetic drive is increased in this condition.
To the Editor:
Uren et al. (July 28 issue)
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conclude that the coronary vasodilator response is severely impaired after myocardial infarction, in both infarcted and uninfarcted myocardial regions. ...However, the results of their studies are complicated by other important changes that occur during and after myocardial infarction, which were not considered.
Dipyridamole is a basic, lipophilic drug that is extensively and avidly bound to serum protein and has a relatively high rate of clearance.
2
At relevant concentrations, over 99 percent of dipyridamole is bound to α1-acid glycoprotein.
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Myocardial infarction causes dramatic (over twofold) time-dependent increases in the concentrations of this . . .
BACKGROUND: The aim of the study was to establish the influence of proximal coronary artery atheroma and smoking habit on the stimulated release of tissue plasminogen activator (tPA) from the heart. ...METHODS AND RESULTS: After diagnostic coronary angiography in 25 patients, the left anterior descending coronary artery (LAD) was instrumented, and the proximal LAD plaque volume was determined by use of intravascular ultrasound (IVUS). Blood flow and fibrinolytic responses to selective LAD infusion of saline, substance P (10 to 40 pmol/min; endothelium-dependent), and sodium nitroprusside (5 to 20 microgram/min; endothelium-independent) were measured by intracoronary IVUS and Doppler, combined with arterial and coronary sinus blood sampling. Mean plaque burden was 5.5+/-0.8 mm(3)/mm vessel (range 0.6 to 13.7 mm(3)/mm vessel). LAD blood flow increased with both substance P and sodium nitroprusside (P<0.001), although coronary sinus plasma tPA antigen and activity concentrations increased only during substance P infusion (P<0.006 for both). There was a strong inverse correlation between the LAD plaque burden and release of active tPA (r=-0.61, P=0.003). Cigarette smoking was associated with impaired coronary release of active tPA (current smokers, 31+/-23 IU/min; ex-smokers, 50+/-33 IU/min; nonsmokers 202+/-73 IU/min; P<0.05). CONCLUSIONS: We found that both the coronary atheromatous plaque burden and smoking habit are associated with a reduced acute local fibrinolytic capacity of the heart. These important findings provide evidence of a direct link between endogenous fibrinolysis, endothelial dysfunction, and atherothrombosis in the coronary circulation and may explain the greater efficacy of thrombolytic therapy for myocardial infarction in cigarette smokers.
Intracoronary stents Uren, Neal G; Chronos, Nicolas Af
BMJ,
10/1996, Letnik:
313, Številka:
7062
Journal Article
Recenzirano
Odprti dostop
An accepted treatment for coronary disease is now coronary angioplasty, which had a primary success rate of 90% in the 1980s, but angioplasty technology has been limited by restenosis, predominantly ...through neointimal hyperplasia, but also through vessel shrinkage. The use of intracoronary stents in both elective and emergency angioplasty to reduce the rates of acute stenosis, emergency surgery and myocardial infarction is discussed.
BACKGROUND: Coronary remodeling plays a significant role in lumen loss in transplant allograft vasculopathy (TxCAD), but the determinants of remodeling are unknown. We assessed the relationship ...between remodeling and plaque topography, coronary compliance, and blood flow in TxCAD. METHODS AND RESULTS: One artery in each of 27 transplant patients was investigated with simultaneous intravascular ultrasound and coronary flow measurements (basal and hyperemic by Doppler flow wire). At 4 to 8 different cross sections (mean 5.1+/-1. 2), plaque topography (concentric or eccentric) was determined, and total vessel area, lumen area, and intimal/medial area (IMA) were measured. Mean remodeling ratio (vessel area/IMA) in eccentric lesions (E, n=28) was significantly larger than that in concentric lesions (C, n=70) (E 5.87+/-0.93 versus C 3.58+/-0.62; P<0.001), despite similar IMA (E 3.89+/-0.68 versus C 3.90+/-0.41; P=NS) and distribution of imaged segments. Remodeling ratio was consistently larger in eccentric lesions in all 3 vessel segments when analyzed separately, and mean remodeling ratio for each artery was larger in vessels with predominantly eccentric lesions. Coronary compliance (Delta lumen area/diastolic lumen area/Delta mean arterial pressure x 10(3)) was also significantly greater in eccentric lesions versus concentric lesions (proximal 1.00+/-0.39 versus 0.22+/-0.04; mid 0.71+/-0.17 versus 0.21+/-0.10; distal 0.43+/-0.13 versus 0. 01+/-0.08; all P<0.01). Coronary flow reserve was also significantly higher in coronary arteries with primarily eccentric lesions (E 2. 49+/-0.64 versus C 1.87+/-0.28; P<0.01). CONCLUSIONS: Vessel remodeling in transplant vasculopathy is significantly greater in eccentric lesions than in concentric lesions, possibly due to greater coronary compliance and resistive vessel function.
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