Late Results After Surgical Closure of Ventricular Septal Defect in Children

Twenty-two children, who were operated on for ventricular septal defects (VSD) at 3-11 years of age, were studied 2-11 years postoperatively with respect to signs of residual shunt, cardiomegaly, physical capacity and pulmonary resistance at various rates of perfusion. There was evidence of residual shunt in one of the patients at follow-up. This was also the only patient who had persisting cardiomegaly in the group. Exercise tests were as a rule within normal limits. Total pulmonary resistance (TPR) decreased in all instances and was abnormally elevated in 6 patients at the follow-up. as compared to 12 at the pre-operative study. Total pulmonary resistance index (TRP¹) was abnormally elevated in 8 patients, as compared to 10 at the pre-operative study. Whereas TPR decreased from an average pre-operative level of 7.9 to 4.2, TPR¹ average remained virtually unchanged. The two most hyper-resistive patients were found to have identically high resistance indices at the follow-up investigation, indicating little effect on the obstructive vascular lesion. During provoked increase of pulmonary blood flow TPR fell further in nearly all patients. The presure/flow characteristics of the pulmonary circulation in patients with normal resting vascular resistance (PVR) followed closely the regression line of a normal material. Conversely the 5 patients with elevation of PVR at test demonstrated a uniformly steep pressure/flow relationship, indicating a rigid vascular basin in these patients. It is suggested that some of the discrepancies that exist in relation to the effect of surgical closure of VSD may be related to the fact that for the most part a growing population is under study. The “natural” history of pulmonary haemodynamics in the growing individual constitutes a potential error for the long-term evaluation of the effect of VSD closure on pulmonary vascular resistance. It is recommended that resistance figures based on body-size-related flow indices are used and that particularly when the postoperative investigation reveals a moderately hyperresistive patient or a “borderline” case, the resistive characteristics of the pulmonary circulation be studied at various flow rates. Our results support the opinion that the VSD patient should be operated on before a markedly obstructive vascular lesion has developed since there is little evidence to suggest a reversibility of the disease.     

先倍领对大鼠微循环和血液流变学的影响

目的 :观察先倍领对血瘀大鼠微循环和血液流变学特性的影响。方法 :SD大鼠 3 0只 ,随机分为空白组、模型组和实验组 ,在连续 14 d中 ,实验组大鼠肌注先倍领注射液 （ 0 .2 5 ml· kg-1 ） ,在第 13天 ,将实验组和模型组大鼠皮下注射肾上腺素 （ 0 .0 7ml· kg-1 ）和冰水刺激造成大鼠急性血瘀模型 ,观察大鼠肠系膜微循环及血液流变学指标 ;空白组和模型组给予同样体积的生理盐水。结果 :先倍领与模型组相比 ,在微循环各指标中均存在显著性差异（ P<0 .0 1） ,在血液流变学各指标中也存在显著性差异 （ P<0 .0 5或 P<0 .0 1）。结论 :先倍领对大鼠的血瘀症状有明显的缓解作用     

Effects of old age on vascular complexity and dispersion of the hepatic sinusoidal network

OBJECTIVES: In old age, there are marked changes in both the structure of the liver sinusoidal endothelial cell and liver perfusion. The objective of this study was to determine whether there are also aging changes in the microvascular architecture and vascular dispersion of the liver that might influence liver function. METHODS: Vascular corrosion casts and light micrographs of young (4 months) and old (24 months) rat livers were compared. Fractal and Fourier analyses and micro-computed tomography were used. Vascular dispersion was determined from the dispersion number for sucrose and 100-nm microspheres in impulse response experiments. RESULTS: Age did not affect sinusoidal dimensions, sinusoidal density, or dispersion number. There were changes in the geometry and complexity of the sinusoidal network as determined by fractal dimension and degree of anisotropy. CONCLUSIONS: There are small, age-related changes in the architecture of the liver sinusoidal network, which may influence hepatic function and reflect broader aging changes in the microcirculation. However, sinusoidal dimensions and hepatic vascular dispersion are not markedly influenced by old age.     

The imbalance between oxygen demand and supply as a potential mechanism in the pathophysiology of heart failure: the role of microvascular growth and abnormalities

In heart failure, a deficient oxygen supply often is a primary cause for myocardial dysfunction. The reverse however, may also be true; the changes that occur in the failing heart may predispose for the existence of tissue hypoxia, which further affects the function of the heart. Specifically, myocardial hypertrophy and accelerated heart rhythm enhance oxygen demand, while supply is hampered short by endothelial dysfunction and diffusion barriers (such as fibrosis, arterial hyperplasia, and myocyte hypertrophy). Another contributory factor may be deficient growth of the microvasculature that does not keep pace with the rate of myocardial hypertrophy. Fewer microvessels have been observed in many forms of cardiomyopathies. On the other hand, some distinct forms of cardiomyopathies are characterized by the compensatory growth of microvessels, or even excess angiogenesis. This review summarizes the knowledge that has been gathered on this topic thus far and discusses factors that mediate myocardial microvessel growth. Furthermore, a paradigm is presented in which the rate of microvessel growth predicts, at least in part, the degree of myocardial dysfunction. Therapies aimed at the restoration of the microcirculation are proposed to preserve and improve myocardial function.     

低剂量替格瑞洛对稳定性冠心病患者冠脉微循环及外周血MHR、NLR的影响

目的 探讨低剂量替格瑞洛对稳定性冠心病(stable coronary heart disease,SCAD)患者冠脉微循环及外周血单核细胞/高密度脂蛋白胆固醇比值（monocyte/high-density lipoprotein cholesterol ratio,MHR）、中性粒细胞/淋巴细胞比值（neutrophil/lymphocyte ratio,NLR）的影响。方法 将2019年1月-2021年2月在南京脑科医院（胸科院区）就诊的SCAD患者138例,按照随机数表法分成A、B、C三组,每组46例,三组患者采取不同抗血小板策略,A组单纯采用阿司匹林治疗,B组采用阿司匹林联合标准剂量替格瑞洛治疗,C组采用阿司匹林联合低剂量替格瑞洛治疗,连续治疗6个月。对比三组患者治疗前后冠脉微循环阻力指数（microcirculatory resistance, IMR）、血小板微颗粒（platelet microparticles, PMPs）及MHR、NLR水平变化情况,三组患者均随访1年,对比三组患者出血情况。结果 治疗后,三组IMR及PMPs水平均较同组治疗前改善,差异有统计学意义（P<0.05）,三组治疗后IMR及PMPs水平比较,差异有统计学意义（P<0.05）,A组IMR及PMPs水平改善程度优于B、C组,差异有统计学意义（P<0.05）,B、C两组治疗后IMR及PMPs改善程度比较差异无统计学意义（P>0.05）;治疗后,三组MHR及NLR水平均较同组治疗前改善,差异有统计学意义（P<0.05）,三组治疗后MHR及NLR水平比较,差异有统计学意义（P<0.05）,B、C组MHR及NLR水平改善程度优于A组,差异有统计学意义（P<0.05）,B、C两组治疗后MHR及NLR改善程度比较差异无统计学意义（P>0.05）;随访1年期间,三组患者大出血发生率比较无统计学差异（P>0.05）,小出血发生率存在明显差异（P<0.05）,进一步进行组间两两比较,A组和C组患者小出血发生率低于B组（P<0.05）,但A组和C组患者小出血发生率比较无统计学差异（P>0.05）。结论 综上所述,SCAD患者采用低剂量替格瑞洛,能帮助改善患者冠脉微循环、降低血栓形成风险及炎症状态,与标准剂量达到的效果相似,同时还可降低出血风险。     

Coronary microcirculation in essential hypertension: a quantitative myocardial contrast echocardiographic approach.

AIMS: The aims of the present study were: (a) to demonstrate whether quantitative myocardial contrast echocardiography can detect the increase in coronary flow induced by dipyridamole infusion vasodilation through the myocardial opacification due to the transit of microbubbles, both at rest and after dipyridamole induced vasodilation; (b) to explore the coronary microcirculatory function before and after dipyridamole in two different models: asymptomatic and relatively young hypertensive patients with a mild degree of left ventricular hypertrophy, and healthy controls. METHODS AND RESULTS: Two groups of strictly age-matched males were studied (case-control study): 10, relatively young and asymptomatic essential hypertensive patients with a mild degree of left ventricular hypertrophy with a normal left ventricular function, and 10 healthy controls. The main findings were: the microbubbles' appearance area was significantly lower in hypertensive patients than in controls (P<0.05) because of a significantly lower time to peak. The peak intensity at rest was higher in hypertensives than in controls (P<0.05); but the per cent increase after vasodilatory stimulus was significantly higher in controls (+71% in controls vs +31% in hypertensives; P<0.05). The microbubbles' disappearance area was comparable in both groups at rest; the per cent increase of this parameter after dipyridamole was significantly higher in controls (+124%) than in hypertensives (+90%) (P<0.05). The results achieved in this study documented that the coronary microcirculation in hypertensive patients presenting a mild degree of left ventricular hypertrophy, explored with quantitative myocardial contrast echocardiography, showed a different behaviour in comparison with controls, in the vasodilatory response to dipyridamole. CONCLUSION: The coronary microcirculation in hypertensives showed a reduced vasodilation capacity of the resistance arterioles under dipyridamole induced vasodilatation, and a possible impairment of the endothelium dependent vasodilation. This happened despite an increase in the left ventricular mass, where the relation between capillary bed distribution and hypertrophied myocardium (rarefaction phenomenon) is not completely respected.     

Effect of glycated LDL on microvascular tone in mice: a comparative study with LDL modified in vitro or isolated from diabetic patients

Aims/hypothesis In vitro studies have suggested that glycation of LDL might be implicated in diabetic microangiopathy. We therefore investigated the in vivo effects of LDL glycated in vitro on the mouse skeletal muscle arteriolar tone. Since glycation naturally occurs during diabetes, we also tested the effects of LDL isolated from diabetic patients.Methods In anaesthetized mice, the spinotrapezius muscle microcirculation was observed, in situ, using the orthogonal polarization spectral imaging technology. The diameter of terminal (<20 µm) and small arterioles (20–40 µm) was measured before and after a bolus intravenous injection of glycated LDL followed by a continuous perfusion (115 µg/kg/min).Results A slight decrease of terminal and small arterioles diameter (<10%) was observed with native LDL and LDL isolated from healthy subjects. In contrast, mildly glycated LDL induced a clear vasoconstriction of arterioles (>15%), which was further increased when highly glycated LDL was perfused (>22%). LDL isolated from diabetic patients mimicked the vasoconstriction obtained with in vitro mildly glycated LDL, which underwent similar glycation as those isolated from diabetic patients.Conclusion/Interpretation Our results show in vivo that acute perfusion of both types of glycated LDL (artificially or naturally modified), cause major microvascular modification by enhancing arteriolar tone in skeletal muscle. These findings highlight a new role of glycated LDL at the level of microvessels. We suggest that glycation of LDL could contribute to the impaired vascular reactivity observed in diabetes.Abbreviations OPS orthogonal polarization spectral - ACEi angiotensin converting enzyme inhibitors - N-LDL native LDL - mG-LDL mildly glycated LDL - hG-LDL highly glycated LDL - H-LDL LDL isolated from healthy subjects - D1-LDL LDL isolated from Type 1 diabetic patients - D2-LDL LDL isolated from Type 2 diabetic patients - TBARS thiobarbituric acid-reactive substances - TNBS trinitrobenzenesulfonic acid - MDA malondialdehyde-(bis(dimethyl acetal))