降压治疗对高血压患者动脉弹性功能的影响

目的　观察降压治疗对动脉弹性功能的影响。方法　选择 6 0例高血压病人 (高血压控制组与高血压未控制组各 30例 )和 30例正常对照组 ,使用DO2 0 2 0动脉功能测定仪检测大动脉弹性指数C1和小动脉弹性指数C2。结果　高血压控制组的C1(10 70± 3 71ml/mmHg× 10 )和C2(3 98± 2 0 9ml/mmHg× 10 0 )均明显高于高血压未控制组C1(7 96± 3 0 1ml/mmag× 10 )和C2 (2 5 0± 1 14ml/mmHg× 10 0 ) (P <0 0 5 ) ,高血压控制组的C1与对照组C1(11 4 2± 1 6 7ml/mmHg× 10 )无显著差别 (P >0 0 5 ) ,但C2低于正常对照组C2 (7 6 7± 1 5 6ml/mmHg× 10 0 ) (P <0 0 5 )。结论　降压治疗能改善高血压患者大动脉和小动脉弹性功能     

老年单纯收缩期高血压的动脉弹性功能变化

目的　比较老年正常血压者、单纯性收缩期高血压 (ISH)与非单纯性收缩期高血压 (NISH)患者的动脉弹性功能 ,了解不同类型老年高血压大动脉和小动脉弹性的差别。方法　选择 5 0例健康老年人 (男女各 2 5例 ,平均年龄 6 8± 5岁 )和 84例老年高血压病人 (男性 39例 ,女性 4 5例 ,平均年龄 6 8± 5岁 ) ,其中单纯性收缩期高血压 (ISH) 6 4例 ,非单纯性收缩期高血压 (NISH) 2 0例。使用DO2 0 2 0动脉功能测定仪检测桡动脉脉搏波形和动脉弹性指数C1和C2 。结果　ISH大动脉弹性指数C1(7± 2 1ml/mmHg× 10 )低于NISH组 (9 2± 3 1ml/mmHg× 10 )和正常血压对照组(12 9± 4ml/mmHg× 10 ) ,P <0 0 1;ISH小动脉弹性指数C2 (2 6± 2 2ml/mmHg× 10 0 )与NISH(2 7± 2 5ml/mmHg× 10 0 )无显著差别 ,均低于正常血压对照组 (4 3± 2 5ml/mmHg× 10 0 ) ,P <0 0 1;在正常血压对照组 ,动脉弹性指数与脉压显著负相关 (C1:r=- 0 6 2 7,P <0 0 0 1;C2 :r =- 0 389,P <0 0 0 1) ,但在ISH则并不相关 (C1:r =- 0 10 5 ,P =0 4 10 ;C2 :r =- 0 2 0 3,P =0 10 8)。结论　老年单纯性收缩期高血压患者大动脉和小动脉弹性功能均有明显减退     

老年单纯收缩期高血压的动脉弹性功能变化

目的比较老年正常血压者、单纯性收缩期高血压(ISH)与非单纯性收缩期高血压(NISH)患者的动脉弹性功能,了解不同类型老年高血压大动脉和小动脉弹性的差别.方法选择50例健康老年人(男女各25例,平均年龄68±5岁)和84例老年高血压病人(男性39例,女性45例,平均年龄68±5岁),其中单纯性收缩期高血压(ISH)64例,非单纯性收缩期高血压(NISH)20例.使用DO2020动脉功能测定仪检测桡动脉脉搏波形和动脉弹性指数C1和C2.结果 ISH大动脉弹性指数C1(7±2.1 ml/mmHg×10)低于NISH组(9.2±3.1 ml/mmHg×10)和正常血压对照组(12.9±4 ml/mmHg×10),P＜0.01;ISH小动脉弹性指数C2(2.6±2.2 ml/mmHg×100)与NISH(2.7±2.5 ml/mmHg×100)无显著差别,均低于正常血压对照组(4.3±2.5 ml/mmHg×100),P＜0.01;在正常血压对照组,动脉弹性指数与脉压显著负相关(C1 r=-0.627, P＜0.001; C2 r=-0.389, P＜0.001),但在ISH则并不相关(C1 r=-0.105, P=0.410; C2 r=-0.203, P=0.108).结论老年单纯性收缩期高血压患者大动脉和小动脉弹性功能均有明显减退.     

冠心病患者血管内皮功能障碍与动脉弹性关系的研究

目的　探讨冠心病患者血管内皮功能障碍与动脉弹性的关系。方法　采用高分辨率血管超声法检测 30例冠心病患者与 30例正常对照组肱动脉血流介导的内皮依赖性血管舒张功能(FMD);应用动脉弹性功能检测仪测定受试者的大动脉弹性指数 (C1 )和小动脉弹性指数 (C2 )。结果　冠心病组血流介导的肱动脉舒张反应明显低于对照组[ (5 17±2 13)% 与 (11 10±4 36)%,P<0 05];冠心病组与正常对照组的C1 差异无统计学意义 [ ( 11 59±4 56 )ml/mmHg( 1mmHg=0 133kPa) ×10与 (12 11±3 82)ml/mmHg×10, P>0 05],但冠心病组的C2 明显低于正常对照组[ (4 20±1 80)ml/mmHg×100与 (6 26±2 36)ml/mmHg×100, P<0 05],冠心病组血流介导的肱动脉舒张反应与C2 呈正相关(r=0 53, P<0 05)。结论　冠心病患者肱动脉内皮依赖血管舒张功能受损和C2 降低,且两者之间呈正相关,提示C2 可作为一种评价血管内皮功能的新指标。     

年龄对血管弹性和内皮细胞功能的影响

目的　本研究采用桡动脉脉搏波分析动脉弹性和激光多普勒血流测定方法评价增龄对内皮细胞功能的影响 ,阐明动脉弹性降低可以用于早期无创评估人的内皮细胞功能。方法　 2 4例无心血管疾病史的男性健康志愿者分为青年组 (年龄 2 0～ 30岁 ,n =12 )和老年组 (年龄 6 0～ 70岁 ,n=12 ) ,离子电渗透法向受试者前臂皮肤导入乙酰胆碱 (acethycholine ,Ach)和硝普钠 (sodiumnitroprusside,SNP) ,激光多普勒流量测定仪测量基础和峰值血流量 ;采用桡动脉脉搏分析法无创性评价大动脉弹性指数 (C1 )和小动脉弹性指数 (C2 )。结果　青年组和老年组的基础血流无明显差异 ,与青年组相比 ,Ach诱导的老年组峰值血流量明显减少 [( 83 4 0± 11 90 )比 ( 93 75± 10 87)PU ,P =0 0 3],而SNP诱导的峰值血流在两组间无明显差异 [( 119 17± 16 76 )比 ( 12 8 33± 2 1 2 9)PU ,P =NS];老年组与青年组比较 ,C1 和C2 明显降低 [C1 ( 11 4 2± 1 6 7)比 ( 16 75± 2 0 9)ml mmHg× 10 ,P <0 0 0 1;C2 ( 7 6 7± 1 5 6 )比 ( 10 75± 1 86 )ml mmHg× 10 0 ,P <0 0 0 1];动脉血管弹性的变化与Ach诱导的皮肤血流改变呈正相关 ,与SNP诱导的皮肤血流改变无关。结论　增龄导致动脉弹性降低和血管内皮功能损害 ,动脉弹性降低     

中国健康人群动脉弹性功能参数研究

目的　建立中国健康人群男、女性和各年龄组大动脉弹性指数 (C1 )和小动脉弹性指数(C2 )的正常参照值 ,评价动脉弹性指数测定短期内的重复性。方法　选择中国 10个城市年龄 15～ 80岁正常血压健康人 192 4例 (男 947,女 977) ,采用动脉弹性功能测定仪CVProfilorDO 2 0 2 0 ,平卧位同步测量并记录 30s肱动脉血压和桡动脉脉搏波形 ,获取C1 和C2 。连续测定 3次 ,每次相隔 4min ,7～ 2 8d后进行重复性检测。结果　中国健康人群C1 和C2 平均值分别为 ( 16 0± 4 1)ml mmHg× 10、( 6 6±3 0 )ml mmHg× 10 0。女性C1 和C2 均低于男性 ,无论男、女性C1 和C2 均与年龄负相关。各地区C1 和C2 平均值的绝对差值较小。根据C1 和C2 与年龄的回归方程 ,已获得不同年龄组男、女性C1 和C2 的正常参照值范围。重复检测的数据较接近 ,尤其是C2 。结论　健康人群动脉弹性指数C1 和C2 受性别、年龄影响 ,应按照男、女性和不同年龄组建立其正常参照值。动脉弹性指数C1 和C2 测定在短期内有较好重复性。     

硝酸甘油对2型糖尿病患者动脉弹性功能的影响

目的　观察大动脉弹性指数C1与小动脉弹性指数C2在 2型糖尿病患者中的变化及硝酸甘油对它们影响。方法　采用CVProfilerDO - 2 0 2 0动脉功能检测仪测定 4 4例 2型糖尿病患者和 5 2名健康人的C1、C2 ,并观察糖尿病患者舌下含服硝酸甘油后C1和C2的变化。结果　糖尿病患者的C2显著低于健康人 (3 4 8± 1 6 5vs 6 70± 2 6 5 ,P <0 0 5 ) ,C1无明显降低 (14 4± 5 2vs 15 2± 3 8,P >0 0 5 ) ;含服硝酸甘油后糖尿病患者的C2明显升高 (4 97± 2 5 8vs 3 4 8± 1 6 5 ,P <0 0 5 ) ,但C1无明显变化 (15 8± 5 5vs 14 4± 5 2 ,P >0 0 5 )。结论　 2型糖尿病患者的小动脉弹性功能 (C2 )显著降低 ,硝酸甘油可有效逆转这一变化。动脉内皮功能障碍可能是 2型糖尿病患者小动脉弹性功能下降的主要原因     

年龄相关的循环内皮祖细胞变化与动脉弹性关系的研究

目的　研究年龄对循环内皮祖细胞及动脉弹性的影响,探讨循环内皮祖细胞水平与动脉弹性损伤的关系。方法　56例健康男性志愿者分成青年组(n=26)和老年组(n=30)。采用桡动脉脉搏分析法无创性评价健康志愿者大动脉弹性指数(C1 )和小动脉弹性指数(C2 ), 流式细胞仪测定外周血中CD34+单个核细胞的水平,单个核细胞体外培养2周,荧光显微镜鉴定FITC UEA I和DiI acLDL双染色阳性细胞为内皮祖细胞。结果　老年组与青年组相比较,C1 和C2 明显降低[C1(11. 73±1 .45)比(16 .89±1 .69)ml/mmHg×10, P<0. 001; C2 (8 .40±1 45)比(10. 58±1 .18)ml/mmHg×100, P<0 .001 ];循环内皮祖细胞数目明显减少[ ( 0 .13±0. 02 )比( 0 .17±0. 04 )%,P<0 .05];循环内皮祖细胞水平与动脉弹性指数变化呈正相关(r=0. 47, P<0. 01;r=0 .4, P<0. 01),荧光显微镜鉴定贴壁细胞FITC UEA I和DiI acLDL双染色阳性。结论　增龄导致循环内皮祖细胞数量减少,提示血管内皮修复能力下降和功能障碍,损伤动脉弹性,循环内皮祖细胞水平有可能作为评价血管功能的替代指标。     

年轻吸烟与既往有吸烟史的无症状年青人动脉搏动功能

Am J of Hypertension,2006,19:897-901.吸烟是一种已经被肯定的心血管病危险因素,能损害动脉脉动功能。该文测定278名非吸烟者,77名现行吸烟者,以及104名既往吸烟者大动脉弹性指数(C1)、小动脉弹性指数(C2)检测大小动脉顺应性,年青人年龄18~44岁,平均36·4岁。与现行吸烟者相较,矫正年龄、种族、性别之后,既往吸烟者,体重指数(BMI)较大(29·6vs27·7kg/m2,P=·02),血糖较高(5·3vs4·8mmol/L,P=0·01),血胰岛素较高(15·0vs10·9mU/L,P=0·01)。既往吸烟者与非吸烟者比较,BMI相似,但血糖稍高(P=0·08)。在动脉脉动功能方面,非吸烟…     

氟伐他汀改善高血压患者脉压和动脉弹性临床研究

目的　观察氟伐他汀对降压治疗中高血压患者脉压和动脉弹性功能的影响。方法　选择 3 0例正在规律服用降压药物治疗并且脉压≥ 60mmHg的高血压患者 ,分为安慰剂组 (15例 )和氟伐他汀组 (15例 ) ,分别加服安慰剂 (1片每天 )或氟伐他汀 (40mg/d) ,治疗 3个月。观察治疗前、后肱动脉血压 ,脉搏波传导速度 (PWV) ,大动脉和小动脉弹性指数 (C1和C2 ) ,从桡动脉压力波形实时获得的中心动脉血压、压力反射波增强指数 (AI)。结果　安慰组治疗后各项指标均无显著改变。氟伐他汀组治疗后肱动脉收缩压与脉压分别降低 8 0± 12 9mmHg (P =0 0 3 1)与 5 7± 9 3mmHg (P =0 0 3 3 ) ,中心动脉收缩压与脉压分别降低 9 7± 12 4mmHg (P =0 0 0 9)与 7 1± 9 3mmHg (P =0 0 1) ,中心动脉下降幅度大于肱动脉 ;舒张压和心率无显著改变 ;C2 升高 (P =0 0 3 ) ;AI降低 (P =0 0 2 6) ;PWV和C1无显著改变。结论　氟伐他汀通过改善高血压患者小动脉弹性和外周压力波反射 ,具有缩小脉压的作用     

Preserved Endothelial Function in Patients With Severe Hypertriglyceridemia and Low Functional Lipoprotein Lipase Activity

Objectives. We sought to determine whether hypertriglyceridemia in patients with lipoprotein lipase (LPL) dysfunction is associated with endothelial dysfunction in resistance vessels of the forearm vasculature.Background. Vasodilator responses to acetylcholine, acting through stimulation of nitric oxide (NO) release from the endothelium, are impaired in hypercholesterolemia and normalized by l-arginine, suggesting dysfunction of the l-arginine/NO pathway. Similar abnormalities have been reported in conditions associated with hypertriglyceridemia, such as non–insulin-dependent diabetes. The relation between endothelial function and plasma triglyceride concentrations has, however, not previously been studied in vivo.Methods. We examined forearm blood flow responses to brachial artery infusions of acetylcholine (alone and with l-arginine) and nitroprusside (an NO donor) in 17 patients with severe hypertriglyceridemia (mean [±SD] plasma triglyceride concentration 1,914 ± 1,288 mg/dl) but normal low density lipoprotein cholesterol (89 ± 31 mg/dl) and in 34 normolipidemic control subjects. Severe LPL dysfunction was demonstrated in 10 of 17 patients.Results. Acetylcholine (7.5 and 15 μg/min) produced similar forearm blood flow responses in hypertriglyceridemic patients (mean [±SEM] 7.7 ± 0.9 and 10.5 ± 1.2 ml/min per 100 ml) and in control subjects (7.5 ± 0.6 and 11.0 ± 0.8 ml/min per 100 ml, p = 0.78 by analysis of variance). Responses to acetylcholine co-infused with l-arginine (10 mg/min) and nitroprusside (3 and 10 μg/min) were also similar in hypertriglyceridemic patients and control subjects (p = 0.93 and p = 0.27 for acetylcholine with l-arginine and nitroprusside, respectively). The ratio response to acetylcholine/response to nitroprusside differed between hypertriglyceridemic patients and control subjects by only 1%. The study had >90% power (alpha = 0.05) to detect a difference >30% in this ratio.Conclusions. Severe hypertriglyceridemia associated with LPL dysfunction is not associated with the degree of endothelial dysfunction seen in moderate hypercholesterolemia when responses to acetylcholine are impaired by >40%.(J Am Coll Cardiol 1997;29:964–8)© 1997 by the American College of Cardiology     

Berberine-induced mobilization of circulating endothelial progenitor cells improves human small artery elasticity

Berberine (BR) has been proved to promote endothelial function. However, the exact mechanisms underlying the effect of BR on endothelial function are not completely clear. It has been demonstrated that endothelial progenitor cells (EPCs) contribute to improvement of endothelial function and C2 small artery elasticity index is a surrogate parameter for the clinical evaluation of endothelial function. We hypothesized that BR-induced mobilization of circulating EPCs is associated with BR-related improvement of endothelial function. To address this assumption, 15 healthy volunteers were recruited and received BR 0.4 g three times per day for 30 days. The number of circulating CD34/KDR double-positive cells as well as C1 large and C2 small artery elasticity indices were evaluated before and after BR therapy. The number of CD34/KDR double-positive EPCs increased significantly after BR treatment (0.030+/-0.020% vs 0.017+/-0.010%, P<0.01). After 30-day BR therapy C2 increased significantly (6.21+/-2.80 ml per mm Hg x 100 vs 4.06+/-2.67 ml per mm Hg x 100, P<0.01) and C1 remained unchanged (10.79+/-3.27 ml per mm Hg x 10 vs 10.06+/-2.08 ml per mm Hg x 10, P>0.05). The increment of CD34/KDR double-positive EPCs was positively correlated with the increment of C2 (r=0.68, P<0.01). We concluded that BR-induced mobilization of circulating EPCs contributes to improvement of small artery elasticity in healthy persons.     

二尖瓣狭窄球囊扩张术前后肾上腺髓质素的分布及变化

本文应用特异性放免方法测定了风湿性心脏病二尖瓣狭窄病人不同部位血浆中肾上腺髓质素前体（ProADM153-185）的分布及其在二尖瓣球囊扩张手术前后即刻的变化。结果显示：风心病二尖瓣狭窄患者血浆中ProADM153-185（Adt）以肺总动脉处含量最高，与其它部位差别显著，而右心房、右心室及下腔静脉根部处之间无明显差异。且除肺总动脉外，心腔其它部位的Adt含量均低于外周静脉血（P＜0.05），上述各部位Adt在二尖瓣球囊扩张术后即刻含量均有所降低，肺总脉189.2±15.1vs168.2±13.2；右心室155．7±10.9vs142.2±13.4；右心房153.3±12.6vs140.9±15.3；下腔静脉156.9±12.3vs147.9±17.3；外周静脉168.3±6.2vs165.5±10.7pg/ml；但下腔静脉及外周静脉及变化无统计学意义，肺总动脉右心房与右心室处Adt降低显著（P＜0.05）。风心病二尖瓣狭窄者外周静脉血血浆中proADM153-185（Adt）的含量与正常人无明显区别。     

Circulating endothelial progenitor cell deficiency contributes to impaired arterial elasticity in persons of advancing age

Reduced arterial elasticity is a hallmark of ageing in healthy humans and appears to occur independently of coexisting disease processes. Endothelial-cell injury and dysfunction may be responsible for this fall in arterial elasticity. We hypothesized that circulating endothelial progenitor cells (EPCs) are involved in endothelial repair and that lack of EPCs contributes to impaired arterial elasticity. A total of 56 healthy male volunteers were divided into young (n=26) and elderly (n=30) groups. Large and small artery elasticity indices were noninvasively assessed using pulse wave analysis. The number of circulating EPCs was measured by using flow cytometry. Cells demonstrating DiI-acLDL and FITC-ulex lectin double-positive fluorescence were identified as EPCs. C1 large artery elasticity and C2 small artery elasticity indices were significantly reduced in the elderly group compared with the young group (11.73+/-1.45 vs 16.88+/-1.69 ml/mm Hg x 10, P<0.001; 8.40+/-1.45 vs 10.58+/-1.18 ml/mm Hg x 100, P<0.001, respectively). In parallel, the number of circulating EPCs was significantly reduced in the elderly group compared with the young group (0.13+/-0.02 vs 0.17+/-0.04%, P<0.05). The number of circulating EPCs correlated with C1 large and C2 small artery elasticity indices (r=0.47, P<0.01; r=0.4, P<0.01). The present findings suggest that the fall in circulating EPCs with subsequently impaired endothelial-cell repair and function contributes to reduced arterial elasticity in humans with ageing. The decrease in circulating EPCs may serve as a surrogate biologic measure of vascular function and human age.     

Characterization of high density lipoproteins from patients with severe hypertriglyceridemia

High density lipoproteins (HDL) were isolated by zonal ultracentrifugation from 6 subjects with severe hypertriglyceridemia. Four subjects had familial endogenous hypertriglyceridemia with fasting chylomicronemia; 2 subjects were non-insulin-dependent diabetics. Plasma triglycerides ranged from 920 to 5440 mg/dl and HDL-cholesterol from 12 to 23 mg/dl. The major HDL from these hypertriglyceridemic subjects had a peak mean density of 1.153 g/ml as compared to 1.140 g/ml for HDL3 from normal subjects. None of the subjects had significant amounts of HDL corresponding to normal HDL2. The major subpopulation of hypertriglyceridemic HDL had a mean diameter of 8.4 +/- 0.1 nm (range 7.6-9.0 nm). The HDL were enriched in triacylglycerols and depleted in cholesteryl esters and the C apoproteins as compared to control HDL3. The mass ratio of triacylglycerols to cholesteryl esters ranged from 4.00 to 5.22 for the patients versus 0.41 for normal HDL3. The increased content of triacylglycerols partially explains the decreased amount of cholesterol associated with these hypertriglyceridemic HDL.     

Potassium Magnesium Supplementation for Four Weeks Improves Small Distal Artery Compliance and Reduces Blood Pressure in Patients with Essential Hypertension

It has been postulated that the loss of arterial compliance may precede cardiovascular diseases, and that arterial compliance is an important parameter to consider when evaluating arterial diseases such as essential hypertension (EH) and the effects of antihypertensive treatment. In all, 133 EH patients and 147 healthy subjects were enrolled in this study. Large arterial compliance (C1) and small arterial compliance (C2) were measured by the CVProfilor? DO-2020 CardioVascular Profiling System. Thirty-five patients randomly received magnesium potassium supplementation (magnesium, 70.8 mg/d; potassium, 217.2 mg/d) for four weeks, and 32 patients received lacidipin (4mg/d) as a control. Before and after the four weeks, blood pressure, C1, and C2 were measured. It was found that arterial compliance was significantly lower in EH patients compared with healthy subjects (C1: 12.53 ± 0.33 vs. 15.63 ± 0.30 ml/mmHg × 10, p < 0.01;C2: 3.79 ± 0.17 vs. 5.69 ± 0.25 ml/mmHg × 100,p < 0.01). On lacidipine, systolic and diastolic BP decreased 13.27 ± 1.76 mm Hg and 6.33 ± 1.55 mm Hg, and C1 and C2 compliance values increased 25.05% ± 4.49% and 34.50% ± 7.40%, respectively. On K⁺ and Mg²⁺ supplementation, systolic and diastolic BP decreased 7.83 ± 1.87 mm Hg and 3.67 ± 1.03 mm Hg, and C1 and C2 compliance values increased 12.44% ± 4.43% and 45.25% ± 6.67%, respectively. Decreases in systemic vascular resistance (mean arterial pressure divided by cardiac output) by 11.9% and 16.6 % (p < 0.01) were seen between the drug-induced changes, respectively. Both large arterial compliance and small arterial compliance were decreased in essential hypertension patients. In essential hypertension patients, magnesium and potassium supplementation could improve small arterial compliance, while lacidipine improved large arterial compliance significantly.     

Impaired Myocardial Vasodilation During Hyperemic Stress With Dipyridamole in Hypertriglyceridemia

Objectives. This study sought to investigate the specific role of hypertriglyceridemia in the myocardial hyperemic stress with dipyridamole/rest flow ratio (MDR).

Background. Reduced MDR has been reported in hypercholesterolemic patients without evidence of ischemia. However, the specific role of hypertriglyceridemia in MDR has not been studied.

Methods. Fifteen nondiabetic normocholesterolemic hypertriglyceridemic patients and 13 age-matched control subjects were studied. Myocardial blood flow (MBF) during dipyridamole administration and baseline MBF in hypertriglyceridemic patients and control subjects were measured using positron emission tomography and nitrogen-13 ammonia, after which the MDR was calculated.

Results. Baseline MBF (ml/min per 100 g heart weight) in hypertriglyceridemic patients (mean ± SD 73.6 ± 24.1) did not differ significantly from that in control subjects (81.6 ± 37.2). MBF during dipyridamole loading in hypertriglyceridemic patients (198 ± 106) was significantly reduced compared with that in control subjects (313 ± 176, p < 0.05), as was the MDR (2.71 ± 1.07 vs. 3.73 ± 1.14, respectively, p < 0.05). Spearman rank-order correlation analysis showed a significant relation between plasma triglyceride concentration and MDR (r = −0.466, asymptotic SE 0.157, p = 0.0125); however, no such significant relation was seen between total plasma cholesterol concentration and MDR (r = −0.369, asymptotic SE 0.130, p = 0.059).

Conclusions. Impaired myocardial vasodilation was suggested in hypertriglyceridemic patients without symptoms and signs of ischemia.