微血管病变与缺血性心脏病

冠状动脉微血管在心肌的血供中起着重要作用,冠状动脉微循环对冠心病的发生、发展、疗效及预后具有重要影响而备受人们重视。目前冠状动脉微血管病变主要分为X综合征和冠脉内慢血流现象,二者都与缺血性心脏病存在着密切的关系,但发病机制有所不同。X综合征主要是冠状动脉微血管痉挛所致,而冠脉内慢血流现象传统上被认为与微血管功能失调有关。此外慢血流现象可能是缺血性心脏病的一种新的发病机制,它可能代表了动脉粥样硬化和内皮功能失调的早期阶段。并且二者在治疗上有所不同。     

Microvascular reactivity in normotensive subjects with a familial predisposition to hypertension

Using the laser-Doppler method we measured blood flow on the nailfold skin to compare the reactivity of cutaneous microcirculation in three groups of normotensive subjects: 11 subjects with a familial predisposition to hypertension without a previous record of high blood pressure, 6 predisposed subjects with a previous record of high blood pressure, and 13 subjects with no predisposition to hypertension. The flow was measured after direct and indirect skin cooling and heating and during postocclusive reactive hyperemia (PRH) after a 10-min occlusion of digital arteries. The frequency of flow oscillations in the second part of the PRH was established. Heart rate spectral analysis was performed based on the monitoring of the peripheral pulse frequency by means of the finapres device. In comparison to the other two groups of subjects, the group with a predisposition and a previous record of high blood pressure displayed a larger surface area in the low frequency band (0.05 to 0.15 Hz) of the heart rate variability power spectrum (the Bonferroni test, P < 0.05). As compared to subjects without predisposition, both groups of predisposed subjects exhibited higher frequency of flow oscillations in the second part of the PRH (the Bonferroni test, P < 0.05). Our results indicate that there could be a change in cutaneous microvascular reactivity of local (most probably myogenic) origin even in normotensive subjects with a predisposition to hypertension, whereas in normotensives with a predisposition and a previous record of high blood pressure there could be also a different cutaneous microvascular reactivity of central (nonvascular) origin.     

心脏磁共振技术在冠状动脉微血管疾病中的运用进展

近年来随着人们对冠状动脉疾病的深入研究,冠状动脉微血管疾病的临床意义日益受到人们的重视,许多现有的证据表明冠状动脉微血管疾病是心脏疾病的病因之一,在冠状动脉疾病的发展中起着重要的作用。心脏磁共振技术具有多序列、多层次、高分辨率的特点,可以一站式地评价心脏的结构、运动及心肌的活性,被广泛运用于心血管疾病的诊疗过程中。现就心脏磁共振技术在冠状动脉微血管疾病中的运用进行综述。     

老年冠心病、高血压无症状性心肌缺血及缺血发生时的心率与血压变化

目的评价老年冠心病及高血压无症状心肌缺血（ＳＭＩ）及相应的心率与血压反应。方法冠心病组５３例，高血压组４５例，同步进行动态心电图、动态血压监测。结果二组缺血型ＳＴ改变为７１．７％与２８．９％，ＳＴ降低幅度２．９±１．４与１．５±０．５ｍｍ，心肌缺血６２７与１０５阵次，其中ＳＭＩ４９３与９３阵次（Ｐ＜０．０５～０．０１）。缺血发生时心率９８±１６ｍｉｎ比发作前６８±８ｍｉｎ、发作后７７±９ｍｉｎ都高（Ｐ＜０．０１），缺血程度与心率呈显著正相关（ｒ＝０．８６５３，Ｐ＜０．００１）；伴心率增加的心肌缺血发作时ＳＢＰ增加２１±１６ｍｍＨｇ，缺血程度与ＳＢＰ改变呈正相关（ｒ＝０．６２５，Ｐ＜０．０５），心率增加不明显或下降者缺血发生时ＳＢＰ改变不明显。结论老年冠心病及高血压患者常出现短暂性心肌缺血，而且多为ＳＭＩ，心肌缺血时常伴有心率、血压的改变。同步动态心电图、动态血压监测能了解心肌缺血时心率及血压的变化情况，为临床治疗选择动态的给药方法提供可靠的依据。     

Microvascular structure and function in salt-sensitive hypertension

In many individuals with essential hypertension, dietary salt can further increase blood pressure by augmentation of an already elevated total peripheral resistance. There is little information on the microvascular changes that contribute to salt-sensitive hypertension in humans, but studies in the Dahl salt-sensitive rat have provided some knowledge of the microcirculation in this form of hypertension. These studies, most of which have used intravital microscopy or isolated vessel technology, are the focus of this review. The salt-induced exacerbation of hypertension in Dahl rats is due to a uniform increase in hemodynamic resistance throughout most of the peripheral vasculature. In the spinotrapezius muscle, this resistance increase is largely due to the intense constriction of proximal arterioles. The mechanisms responsible for this increased arteriolar tone include increased responsiveness to oxygen and a loss of tonic nitric oxide (NO) availability caused by reduced endothelial NO production and/or accelerated NO degradation by reactive oxygen species. Within the last decade, it has become increasingly clear that high salt intake can also lead to changes in microvascular structure and function in the absence of increased arterial pressure. This effect must also be considered when evaluating microvascular changes and their functional consequences in salt-sensitive hypertension.     

冠状动脉微血管疾病诊疗进展

冠状动脉微血管疾病(coronary microvascular disease,CMD)是指影响冠状动脉微循环结构和功能的疾病,在有心血管危险因素的患者中普遍存在,并增加患者发生不良心血管事件的风险.目前围绕CMD仍有诸多疑点,现就CMD的诊断和治疗的最新进展予以综述.     

高血压冠心病患者清晨血压回升与缺血性ST段改变的相关性

目的通过动态血压监测（ＡＢＰＭ）清晨血压变化参数与动态心电图（Ｈｏｌｔｅｒ）对应时域的缺血性ＳＴ段演变的相关性研究，观察高血压合并冠心病患者血压改变是否与Ｈｏｌｔｅｒ所示心肌缺血改变存在相关性。方法对７９例高血压合并冠心病患者，行同步ＡＢＰＭ与Ｈｏｌｔｅｒ检查２４ｈ，获得的血压变化和ＳＴ段压低数据由计算机进行统计分析。结果清晨血压（收缩压、平均脉压、舒张压）与对应时域的ＳＴ段压低呈正相关关系（Ｐ＜０．０５，ｒ＝０．３９，０．１８，０．３３）；尤以血压（收缩压、平均脉压、舒张压）回升值、心肌耗氧量与夜间均值之差跟对应ＳＴ段压低的相关性更为显著（Ｐ＜０．０１，ｒ＝０．３８，０．１３，０．２９，０．２３）。昼夜节律消失组较昼夜节律存在组发生ＳＴ段缺血性改变的构成比具有显著性差异（Ｐ＜０．０５）。结论清晨清醒前后血压升高与心肌缺血的发生呈直线正相关，且多为无痛性心肌缺血，尤以昼夜节律消失者为著。     

Aortic Stiffness Is Associated with Coronary Microvascular Dysfunction in Patients with Non-obstructive Coronary Artery Disease

ObjectiveAssociations between aortic stiffness and cardiovascular disease events are mediated in part by pathways that include coronary microvascular dysfunction (CMD) and remodeling. However, the relationship between aortic stiffness and CMD remains unclear.The present study aimed to determine whether aortic stiffness causes CMD as evaluated by the hyperemic microvascular resistance index (hMVRI) in patients with non-obstructive coronary artery disease (CAD).MethodsThe intracoronary physiological variables in 209 coronary arteries were evaluated in 121 patients with non-obstructive CAD (fractional flow reserve >0.80) or reference vessels. The cardio-ankle vascular index (CAVI) as a measure of aortic stiffness and atherosclerotic risk factors were also measured.ResultsUnivariate analyses showed that hMVRI correlated with age (β=0.24, p=0.007), eicosapentaenoic acid (EPA; β=-0.18, p=0.048), EPA/arachidonic acid (AA) (EPA/AA) ratio (β=-0.22, p=0.014) and CAVI (β=0.30, p=0.001). A multivariate regression analysis identified CAVI (β=0.25, p=0.007) and EPA/AA ratio (β=-0.26, SE=0.211, p=0.003) as independent determinants of hMVRI.ConclusionAortic stiffness may cause CMD in patients with non-obstructive CAD via increased coronary microvascular resistance. Aortic stiffness is associated with CMD which is evaluated as hyperemic microvascular resistance in patients with non-obstructive CAD.     

Microvascular thrombosis models in venules and arterioles in vivo

Platelets are intimately involved in hemostasis and thrombosis. Under physiological conditions, circulating platelets do not interact with microvascular walls. However, in response to microvascular injury, platelet adhesion and subsequent thrombus formation may be observed in venules and arterioles in vivo. Numerous intravital video microscopy techniques have been described to induce and monitor the formation of microvascular thrombi. The mechanisms of microvascular injury vary widely among different models. Some models induce platelet activation with minimal effects on endothelium, others induce endothelial inflammation or injury, while other models lead to thrombus formation associated with endothelial denudation. The molecular mechanisms mediating platelet-vessel wall adhesive interactions differ among various models. In some instances, differences in responses between venules and arterioles are described that cannot be explained solely by hemodynamic factors. Several models for induction of microvascular thrombosis in vivo are outlined in this review, with a focus on the mechanisms of injury and thrombus formation, as well as on differences in responses between venules and arterioles. Recognizing these characteristics should help investigators select an appropriate model for studying microvascular thrombosis in vivo.     

ECG Diagnosis of Coronary Artery Disease

Objective: In order to assess the diagnostic accuracy of ST depression in the diagnosis of coronary artery disease (CAD) in patients with suspected myocardial ischemia we compared ST depression in 3-lead ambulatory ECG (AECG) with that of exercise tolerance testing (ETT). Methods: Significant coronary artery stenosis in coronary angiography was used as a standard reference. ST analysis could be performed in 106 of the investigated 113 patients, all with suspected CAD. One person with left bundle branch block was excluded from the ST analysis, and six persons could not perform ETT. Results: Seventy-eight of the 106 patients had at least one significant stenosis (> 70% narrowing) and 28 had no stenosis according to coronary angiography. The sensitivity for AECG was 62% and for ETT it was 63%, the specificity for AECG was 79% and for ETT the specificity was 57%. The accuracy for AECG was 66%, and for ETT it was 61%. We also evaluated late potentials (LPs) from the AECG tapes in order to correlate LP to left ventricular function (LVF), myocardial infarction (Ml), and/or CAD. We found that LP correlates better to advanced CAD than to Ml or LVF. Conclusion: The accuracy of ST diagnosis of CAD in patients with suspected myocardial ischemia using AECG was equal to that of a maximal ETT. LP finding from an AECG tape may support the argument for CAD in patients with ST depressions at AECG.     

原发性高血压超声心动图的性别差异

目的研究高血压病人超声心动图的性别差异。方法1～2级原发性高血压病人108例,其中女性病例组(PGf)52例,男性病例组(PGm)56例;正常血压者42例作对照,其中女性对照组(CGf)20例,男性对照组(CGm)22例。所有受试者用Aspen电脑声像仪行超声心动图检查。检测受试者左心房和左心室结构和功能的相关指标,测值取5个心动周期测值的平均值。指标数据以(x±s)表示,以t检验进行统计学分析。结果与PGm相比,PGf的超声心动图具有以下特点:LAID、MVa较大[(37.24±5.88vs32.14±3.80)mm,P<0.01和(84.18±12.13vs81.71±12.30)/s,P<0.05];LVMI[(119.26±22.33)g/m2vs(128.17±27.00)g/m2,P<0.05]、EF(75.13%±6.69%vs83.00%±3.68%,P<0.01)、FS(41.67%±7.99%vs49.03%±7.35%,P<0.01)、MVe[(68.28±8.66)/svs(73.73±11.46)/s,P<0.05]和MVe/a(0.83±0.08vs0.93±0.11,P<0.01)均较小。CGf和CGm之间的上述指标差别无显著性。结论高血压病人的超声心动图存在性别差异,女性高血压病人较男性更易出现心脏结构和功能损害。     

Retinal Microvascular Signs and Cognitive Impairment

OBJECTIVES: To examine the association between retinal microvascular signs, as a proxy for cerebral microvascular disease, and cognitive impairment.
DESIGN: Cross-sectional population-based study.
SETTING: Urban population survey
PARTICIPANTS: One thousand nine hundred eighty-eight persons aged 49 to 97.
MEASUREMENTS: All participants underwent retinal photography and had the Mini-Mental State Examination (MMSE) administered by trained personnel. Retinal photographs were masked and graded for retinopathy signs (microaneurysms, hemorrhages, hard exudates, cotton wool spots), and retinal vessel calibers were measured using a validated computer-assisted method. Cognitive impairment was defined as an MMSE score of 23 or less, in line with other epidemiological studies.
RESULTS: Cognitive impairment was present in 121 participants (6.1%). In the total population, after adjusting for age, sex, blood pressure, diabetes mellitus, smoking, cardiovascular disease, education, and other factors, retinal venular dilation was associated with cognitive impairment (odds ratio (OR)=1.8, 95% confidence interval (95% CI)=1.0–3.2, P =.03). In persons with hypertension, retinopathy signs (adjusted OR=1.7, 95% CI=1.0–3.2, P =.05) and retinal venular dilation (adjusted OR=2.7, 95% CI=1.2–6.1, P =.01) were associated with cognitive impairment.
CONCLUSION: Retinal microvascular signs are associated with significant cognitive impairment, particularly in older persons with hypertension. These findings suggest that cerebral microvascular changes may contribute to cognitive deterioration.     

原发性高血压超声心动图的性别差异

目的研究高血压病人超声心动图的性别差异.方法1～2级原发性高血压病人108例,其中女性病例组(PGf) 52例,男性病例组(PGm)56例;正常血压者42例作对照,其中女性对照组(CGf) 20例,男性对照组(CGm)22例.所有受试者用Aspen电脑声像仪行超声心动图检查.检测受试者左心房和左心室结构和功能的相关指标,测值取5个心动周期测值的平均值.指标数据以(-x±s)表示,以t检验进行统计学分析.结果与PGm相比,PGf的超声心动图具有以下特点LAID、MVa较大[(37.24±5.88 vs 32.14±3.80)mm,P＜0.01和(84.18±12.13 vs 81.71±12.30)cm/s,P＜0.05];LV-MI[(119.26±22.33)g/m2vs(128.17±27.00)g/m2,P＜0.05]、EF(75.13%±6.69%vs 83.00%±3.68%,P＜0.01)、FS(41.67%±7.99%vs 49.03%±7.35%,P＜0.01)、MVe[(68.28±8.66)cm/s vs(73.73±11.46)cm/s,P＜0.05]和MVe/a(0.83±0.08 vs 0.93±0.11,P＜0.01)均较小.CGf和CGm之间的上述指标差别无显著性.结论高血压病人的超声心动图存在性别差异,女性高血压病人较男性更易出现心脏结构和功能损害.     

Microvascular perfusion and transport in the diabetic heart

Diabetes is a chronic disease of metabolic dysfunction that is increasing world-wide. The hyperglycemia associated with diabetes causes significant protein alterations and an oxidative stress. In the heart, all cell types are affected by diabetes: the myocyte, the vasculature and the blood cells. Four out of five diabetics die from ischemic heart disease and stroke, suggesting that the diabetic is quite vulnerable to ischemic injury. It is important to understand the pathophysiologic challenges that occur in the diabetic heart in order to develop thoughtful treatments to limit this serious complication. This review focuses on the anatomical and functional alterations that occur in the diabetic circulation of the heart, with emphasis on the coronary microcirculation. Coronary microvascular dysfunction combined with blood cellular alterations are presented to explain the amplified oxidative stress that occurs in the diabetic heart under ischemic conditions.     

冠状动脉微血管功能障碍的研究进展

梗死相关动脉开通后,微血管功能障碍常常是影响急性心肌梗死患者生存率的重要因素。冠脉微血管功能障碍被认为是由于微血管阻塞/抵抗和/或再灌注损伤及炎症反应导致。对于微血管功能障碍的深入认识,有助于提高急性心肌梗死患者的组织灌注水平,提高患者生存率。     

Microvascular Architecture and Exchange in Teeth

Dental pulp is a low-compliance tissue surrounded by an avascular hard tissue case. Resin casts of the microvasculature in teeth of limited growth show arterioles and venules arranged axially in the pulp with capillary loops extending out toward the dentine. The capillary density is high. There is ultrastructural evidence for lymphatics in pulp. Pulpal blood flow has been estimated in intact teeth using radiolabeled microspheres and found to be in the range 20–60 ml/min per 100 g tissue. One of the difficulties of studying this tissue is that a cavity has to be cut into the tooth with the inherent risks that this may affect the parameters under study. Measurements from exposed pulp indicate that the tissue fluid pressure is high and pulsatile. Furthermore, micropuncture studies have shown that the arteriolar pressure is lower and the venular pressure higher than in other tissues. When dentine is exposed in vivo, fluid moves out through the dentinal tubules and this appears to be formed by a process of ultrafiltration from the pulpal interstitial fluid. The flow is sufficient to retard significantly the diffusion of chemicals into dentine from the oral cavity.