Pulsatile blood flow in arteries: An analytical and numerical study based on the Womersley algorithm / 医用生物力学

Objective To conduct a comprehensive study on pulsatile blood flow in arteries by proposing a convenient theoretical research system for hemodynamics. Methods Based on Womersley algorithm for fully developed pulsatile flow, numerical algorithm was introduced to establish the solving and analytical system of hemodynamics based on flow rate in arteries during one cardiac cycle. The flow rate of carotid artery in pig was measured under three blood flow states: the ideal state with a sinusoidal inflow waveform, the normal physiological state and the enhanced external counterpulsation (EECP) state for comprehensive hemodynamic research. Results Important hemodynamic parameters such as the axial speed vector, the wall shear stress (WSS), and the oscillatory shear index (OSI) during one cardiac cycle under the mentioned three flow states were solved respectively. The waveform of flow rate had a certain effect on WSS distributions and OSI level; the EECP performance obviously resulted in a significant increase in the level of WSS (WSS peak in particular) and OSI. Conclusions The solving system developed in this paper can be used for hemodynamics study conveniently and effectively. One of the most important hemodynamic mechanisms that lead to EECP’s good clinical effect may lie in its promotion to WSS level under physiological state, but the effect of OSI on endothelial function of the artery might much smaller than WSS itself; therefore, OSI may not be an ideal hemodynamic index for predicting the lesion of atherosclerosis.

Transplantation of human umbilical cord-derived endothelial progenitor cells promotes re-endothelialization of the injured carotid artery after balloon injury in New Zealand white rabbits / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cell transplantation has great potential for promoting endothelial repair and reducing the complications of percutaneous coronary intervention (PCI). The aim of this study was to investigate the effect of transplantation of human umbilical cord blood endothelial progenitor cells (EPCs) on injured arteries.</p><p><b>METHODS</b>Umbilical cord blood mononuclear cells were obtained from post-partum lying-in women, and EPCs were isolated, cultured, expanded and identified by immunofluorescence. The carotid arterial endothelium of New Zealand white rabbits was injured by dilatation with a 3F balloon, and the EPCs were injected into the lumen of the injured artery in the transplanted group (n = 16), while an equal volume of phosphated buffered saline (PBS) was injected into the control group after balloon injury (n = 16). The animals were sacrificed after either 2 or 4 weeks, and the grafted cells were identified by double immunofluorescence staining with human nuclear antigen (HNA) and CD31 antibodies. Arterial cross sections were analyzed by pathology, immunohistochemistry and morphometry to evaluate the reparative effects of EPCs. Proliferating cell nuclear antigen (PCNA) and transforming growth factor (TGF)-β1 mRNA expression were detected by reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Fluorescence-labeled EPCs were found in the neointima. The neointimal area and the neointimal/medial area ratio were significantly lower in the transplanted group than in the control group (P < 0.05). von Willebrand factor (vWF) immunohistostaining showed more VWF-positive cells in the transplanted animals than in the controls (8.75 ± 2.92 vs. 4.50 ± 1.77, P < 0.05). Compared with the control group, the transplanted group had lower expression of PCNA mRNA (0.67 ± 0.11 vs. 1.25 ± 0.40, P < 0.01) and higher expression of TGF-β1 mRNA (1.10 ± 0.21 vs. 0.82 ± 0.07, P < 0.05).</p><p><b>CONCLUSIONS</b>EPCs derived from human umbilical cord blood were successfully transplanted into injured vessels. The transplanted EPCs inhibited neointimal hyperplasia and promoted vascular re-endothelialization.</p>

Defective T wave combined with incomplete right bundle branch block: a new electrocardiographic index for diagnosing atrial septal defect / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Incomplete right bundle branch block (ICRBBB) is commonly associated with atrial septal defect (ASD), but lacks sufficient diagnostic test characteristics. An abnormal T wave is also often observed in ASD, with horizontal or inverted displacement of the proximal T wave limb in the right precordial leads, termed "defective T wave" (DTW).</p><p><b>METHODS</b>We examined the diagnostic test characteristics of combining ICRBBB with DTW as a new index to diagnose ASD. A total of 132 consecutive patients with ASD and 132 cases of age/gender-matched controls without ASD were enrolled.</p><p><b>RESULTS</b>Sensitivities of DTW, ICRBBB, and both were 87.1% - 87.9%. Specificities were 97.0%, 96.2%, and 100%, respectively. Positive predictive values were 1.3%, 1.1%, and 100.0% respectively, while negative predictive values were 99.9% for each.</p><p><b>CONCLUSION</b>Combining ICRBBB with DTW in electrocardiogram (ECG) as a new index significantly increased the specificity and positive predictive values while maintaining a high sensitivity in diagnosing ASD.</p>

Enhanced external counterpulsation promotes growth cytokines-mediated myocardial angiogenesis in a porcine model of hypercholesterolemia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Enhanced external counterpulsation (EECP) improves ischemia in patients with refractory angina pectoris, but the mechanism remains unclear. To explore the mechanisms of EECP action, we detected progenitor cells presenting any of the following markers CD34(+), CD29(+), and CD106(+).</p><p><b>METHODS</b>Growth cytokines-mediated progenitor cell mobilization and associated angiogenesis potential were assessed in a porcine model of hypercholesterolemia. Twenty-four male domestic swines were randomly assigned to 4 groups: normal diet (control, n = 6), hypercholesterolemic diet (CHOL, n = 6), hypercholesterolemic diet with administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) (rhG-CSF, n = 6), and hypercholesterolemic diet with EECP treatment (EECP, n = 6). EECP was applied 2 hours every other day for a total of 36 hours. Serum levels of vascular endothelial growth factor (VEGF) and granulocyte colony-stimulating factor (G-CSF), peripheral blood progenitor cell counts, level of regional angiogenesis, and expression of VEGF and stromal cell derived factor 1alpha (SDF-1alpha) in porcine myocardium were assessed, respectively.</p><p><b>RESULTS</b>A porcine model of hypercholesterolemia-induced arteriosclerosis was successfully established. There was no significant difference in serum levels of VEGF among the four groups. The serum levels of G-CSF in the EECP group increased significantly at week 15 and week 18 ((38.3 +/- 5.6) pg/ml at week 15 vs (26.2 +/- 3.7) pg/ml at week 12, P < 0.05, and (46.9 +/- 6.1) pg/ml at week 18 vs (26.2 +/- 3.7) pg/ml at week 12, P < 0.01). The serum levels of G-CSF in group 3 increased also significantly after receiving rhG-CSF injection for five days ((150 +/- 13.9) pg/ml at week 18 vs (24.8 +/- 5.4) pg/ml at week 12, P < 0.01). Compared to other groups and other time points, progenitor cell counts increased significantly after 2-hour EECP treatment (108 +/- 13 vs 26 +/- 6 per 10(5) leukocytes, P < 0.01), but not at week 18. The progenitor cell counts also increased significantly after subcutaneous injection of rhG-CSF for five days compared to the week 12 (baseline) (180 +/- 21 vs 25 +/- 7 per 10(5) leukocytes, P < 0.01). There was no significant difference among the four groups at other time points. Moreover, the expression of VEGF and SDF-1alpha and the level of regional angiogenesis in myocardium increased significantly in both EECP and rhG-CSF groups.</p><p><b>CONCLUSIONS</b>The results demonstrated that EECP could facilitate angiogenesis in the myocardium of atherosclerotic swines by increasing endogenous G-CSF, inducing an enhanced mobilization of progenitor cells and augmenting myocardial expression of VEGF and SDF-1alpha.</p>

Human umbilical cord-derived endothelial progenitor cells promote growth cytokines-mediated neorevascularization in rat myocardial infarction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Cell-based vascular therapies of endothelial progenitor cells (EPCs) mediated neovascularization is still a novel but promising approach for the treatment of ischemic disease. The present study was designed to investigate the therapeutic potentials of human umbilical cord blood-derived EPCs (hUCB-EPCs) in rat with acute myocardial infarction.</p><p><b>METHODS</b>Human umbilical cord blood (hUCB) mononuclear cells were isolated using density gradient centrifugation from the fresh human umbilical cord in healthy delivery woman, and cultured in M199 medium for 7 days. The EPCs were identified by double-positive staining with 1, 1'-dioctadecyl-3, 3, 3', 3'-tetramethylindocarbocyanine percholorate-labeled acetylated low-density lipoprotein (Dil-Ac-LDL) and fluorescein isothiocyanate-conjugated Ulex europaeus lectin (FITC-UEA-l). The rat acute myocardial infarction model was established by the ligation of the left anterior descending artery. The hUCB-EPCs were intramyocardially injected into the peri-infarct area. Four weeks later, left ventricular function was assessed by a pressure-volume catheter. The average capillary density (CAD) was evaluated by anti-VIII immunohistochemistry staining to reflect the development of neovascularization at the peri-infarct area. The graft cells were identified by double immunofluorescence staining with human nuclear antigen (HNA) and CD31 antibody, representing human origin of EPCs and vascular endothelium, respectively. Expressions of cytokines, proliferating cell nuclear angigen (PCNA), platelet endothelial cell adhesion molecule (PECAM) and vascular endothelial growth factor (VEGF) were detected to investigate the underlying mechanisms of cell differentiation and revascularization.</p><p><b>RESULTS</b>The donor EPCs were detectable and integrated into the host myocardium as confirmed by double-positive immunofluorescence staining with HNA and CD31. And the anti-VIII staining demonstrated a higher degree of microvessel formation in EPCs transplanted rats, associated with a significant improvement of global heart function in terms of the increase of left ventricular end-systolic pressure (LVESP), +dp/dtmax and -dp/dtmax as well as the decrease of LVEDP in rats with EPCs therapy comparing to the control rats (P < 0.05). Moreover, the expression of the rat PCNA mRNA and PECAM were both enhanced in the EPCs group compared with that of the control group.</p><p><b>CONCLUSIONS</b>The human umbilical cord blood-derived EPCs could incorporate into new-born capillaries in rat myocardium, induce revascularization and improve the proliferation activity in the peri-infarct area, resulting in the improvement of global heart function. This may indicate a promising stem cell resource in cell-based therapy for ischaemic diseases.</p>

Effect of chronic enhanced external counterpulastion on gene expression profiles of arterial endothelial cells of pigs fed with high-cholesterol diet / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of chronic enhanced external counterpulastion (EECP) on gene expression profiles of arterial endothelial cells (ECs) of pigs fed with high-cholesterol diet.</p><p><b>METHODS</b>Eight male pigs were fed with high-cholesterol diet for 12 weeks to induce arteriosclerosis and subjected to EECP for accumulative 36 h (2 h every other day for 18 sessions). Another 8 pigs on cholesterol-enriched diet and 6 normally fed pigs served as the arteriosclerosis model group and normal control group, respectively, and the high-cholesterol diet was maintained until the end of EECP treatment. The coronary artery was then isolated for transmission electro microscopy, and the abdominal aorta was observed using Sudan III staining. The gene expression profiles in ECs from the thoracic aorta using cDNA microarrays.</p><p><b>RESULTS</b>Macrophages and foam cells were detected beneath the ECs in the coronary artery of pigs in the model group, but not in the other two groups. The ratios of Sudan III-positive area in the celiac aorta were significantly lower in normal control and EECP groups than in the model control group (P<0.05). Compared with the normal control group, the gene expressions of integrins-beta1 and CTGF were up-regulated in the model group. Compared with the model group, the expressions of integrins-beta1, CTGF and VCAM-1 were down-regulated and eNOS up-regulated in EECP group.</p><p><b>CONCLUSION</b>Chronic EECP may reduce endothelial injury, down-regulate the gene expression level of integrin-beta1, CTGF and VCAM-1, lower cholesterol uptake and attenuate arterial endothelial inflammation to protect the pigs fed with high-cholesterol diet from arteriosclerosis.</p>

Transplanted human umbilical cord blood mononuclear cells improve left ventricular function through angiogenesis in myocardial infarction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Human umbilical cord blood contains an abundance of immature stem/progenitor cells, which may participate in the repair of hearts that have been damaged by myocardial infarction (MI). This study aimed to evaluate the effects of human umbilical cord blood mononuclear cells (hUCBC) transplantation on cardiac function and left ventricular remodeling in rat model of MI.</p><p><b>METHODS</b>Forty-five male Wistar rats were randomized into three groups: MI or control group (n = 15), MI plus cell transplantation (n = 15), and sham group (n = 15). Acute myocardial infarction (AMI) was established by ligating the left anterior descending artery, thereafter, hUCBC were implanted into the marginal area of infarcted myocardium. In MI/control group, DMEM was injected instead of hUCBC following the same protocol. Left ventricular function assessment was carried out by echocardiography and invasive hemodynamic measurements one month post MI. All rats were sacrificed for histological and immunochemical examinations.</p><p><b>RESULTS</b>The transplanted hUCBC survived and engaged in the process of myocardial repair in the host heart. Echocardiography demonstrated that left ventricular function improved significantly in the rats that underwent cell transplantation. Hemodynamic studies found a significantly decreased left ventricular end-diastolic pressure (LVEDP) [(21.08 +/- 8.10) mmHg vs (30.82 +/- 9.59) mmHg, P < 0.05], increase in +dp/dt(max) [(4.29 +/- 1.27) mmHg/ms vs (3.24 +/- 0.75) mmHg/ms, P < 0.05), and increase in -dp/dt(max) [(3.71 +/- 0.79) mmHg/ms vs (3.00 +/- 0.49) mmHg/ms, P < 0.05] among MI group with hUCBC transplantation when compared with MI/control group. Masson's trichrome staining revealed that the collagen density in the left ventricle was significantly lower in rats of transplantation group than that in the MI control groups [(6.33 +/- 2.69)% vs (11.10 +/- 3.75)%, P < 0.01]. Based on immunostaining of alpha-actin, the numbers of microvessels were significantly (P < 0.01) increased at the boundary of infarction site. Similarly higher mRNA expression of vascular endothelial growth factor (VEGF) 164 and VEGF188 were found at 7- and 28-day post cell transplantation in MI group with hUCBC transplantation when compared with MI/control group.</p><p><b>CONCLUSIONS</b>Transplanted hUCBC can survive in host myocardium without immunorejection, significantly improve left ventricular remodeling after AMI and promote a higher level of angiogenesis in the infarct zones. All these factors beneficially affect cardiac repair in the setting of MI. Therefore human umbilical cord blood may be potential source for cell-based therapy for AMI.</p>

Effects of enhanced external counterpulsation in atherosclerosis and NF-kappaB expression: a pig model with hypercholesterolemia / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the effects of enhanced external counterpulsation (EECP) on the vascular morphology, and endothelial function using experimentally induced hypercholesterolemic pigs.</p><p><b>METHODS</b>Thirty five male pigs were randomly divided into three groups: 7 normal control animals, 11 hypercholesterolemic animals, and 17 hypercholesterolemic animals receiving EECP. Serum cholesterol was measured. The coronary arteries and aortas were sampled for histopathologic and ultrastructural examination. The NF-kappaB protein expression of porcine coronary arteries was investigated by immunofluorescence.</p><p><b>RESULTS</b>Compared with the normal controls, serum cholesterol levels were significantly higher in the hypercholesterolemic animals with or without EECP. The plaque/intimal area ratio of the aorta decreased significantly in animals receiving EECP [(3.33 +/- 2.40)%, versus (12.03 +/- 7.12)% in those without EECP, P < 0.05]. Lipid deposition, endothelial damage and proliferation of smooth muscle cells were less severe in animals receiving EECP than those not. Moreover, activation and expression of NF-kappaB also decreased significantly (P < 0.05) in animals receiving EECP.</p><p><b>CONCLUSIONS</b>EECP improves the morphology and function of vascular endothelium, and retards the development and progression of atherosclerosis, likely through the inhibition of NF-kappaB signaling pathway.</p>

Beneficial effects of human umbilical cord blood mononuclear cells transplantation on rats with experimental myocardial infarction / 中华心血管病杂志

<p><b>OBJECTIVE</b>Human umbilical cord blood contains abundant immature stem/progenitor cells, which may contribute to the repair of infarcted myocardium. Present study aimed to explore the feasibility and effects of human umbilical cord blood mononuclear cells (HUCBC) transplantation for the treatment of myocardial infarction.</p><p><b>METHODS</b>Forty-five male Wistar rats were randomly divided into three groups: (1) Myocardial infarction (MI plus vehicle, n = 15), (2) MI plus cell transplantation (HUCBC were implanted into the peri-infarct area immediately after MI, n = 15), (3) Normal control group (n = 15). After echocardiography and hemodynamic measurements, the rats were sacrificed for histological and immunochemical examinations one month post MI.</p><p><b>RESULTS</b>The transplanted HUCBC survived and participated the repair process in host heart. Significantly improved left ventricular function was evidenced by echocardiography in cell transplantation group compared to the MI control group. Left ventricular end-diastolic pressure was significantly reduced LVEDP (21.08 +/- 8.10) vs (30.82 +/- 9.59) mm Hg, P < 0.05], +dp/dt(max) [(4.29 +/- 1.27) vs (3.24 +/- 0.75) mm Hg/ms, P < 0.05] and -dp/dt(max) increased [(3.71 +/- 0.79) vs (3.00 +/- 0.49) mm Hg/ms, P < 0.05] in cell transplantation rats compared with MI control rats. vWF immunostaining examination showed significantly increased microvessels within the boundary of infarcted myocardium in cell transplantation group compared to the MI control group (P < 0.01).</p><p><b>CONCLUSIONS</b>HUCBC transplantation may improve cardiac function in MI rats by promoting microvessel formation.</p>

Microvessel angiogenesis: a possible cardioprotective mechanism of external counterpulsation for canine myocardial infarction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Enhanced external counterpulsation (EECP) has been demonstrated to be effective in the treatment of patients with coronary artery disease (CAD). It has been proposed that the beneficial effects of EECP observed in clinical studies may be due to the formation of new blood vessels (angiogenesis) and collateral development. However, there is a relative paucity of basic studies to support the proposed mechanisms.</p><p><b>METHODS</b>Twelve Beagle dogs were anesthetized with 3% sodium pentobarbital, 1 mg/kg intraperitoneal injection and mechanically ventilated for the development of myocardial infarction. After coronary occlusion, all animals were randomly assigned to either EECP or control. EECP was given one hour per day, 5 days a week, for a total of 28 to 30 hours treatment over a 6-week course. Immunohistochemical studies of alpha-actin and von Willebrand factor (vWF) were used to detect newly developed microvessels. Systemic and local vascular endothelial growth factor (VEGF) were identified by enzyme linked immunosorbent assay (ELISA) and reverse-transcriptional polymerase chain reaction (RT-PCR) analysis.</p><p><b>RESULTS</b>There was a significant increase in the density of microvessels per mm(2) in the infarcted regions of EECP group compared to control group (vWF, 15.2 +/- 6.3 versus 4.9 +/- 2.1, P < 0.05; alpha-actin, 11.8 +/- 5.3 versus 3.4 +/- 1.2, P < 0.05), along with significant increase of positive vWF and alpha-actin stained area. Both immunohistochemical staining and RT-PCR analysis documented a significant increase in VEGF expression. These factors associated with angiogenesis corresponded to improved myocardial perfusion by 99mTc-sestamibi single-photon emission computed tomography.</p><p><b>CONCLUSION</b>Microvessel angiogenesis may be a mechanism of action for the improved myocardial perfusion after EECP therapy.</p>

Efficacy and restenosis of cypher stent in elderly patients with coronary heart disease / 中华老年医学杂志

Objective To investigate the efficacy and security of cypher stent(sirolimus-eluting stent)in the treatment of old patients with coronary heart disease(CHD).Methods From November 2002 to May 2005,328 elderly CHD cases(age:60-86 years)were treated with 415 Cypher stents.Among the 328 patients,66 had ST-segment elevation of myocardial infarction,21 had non ST-segment elevation of myocardial infarction,149 had unstable angina and 92 had stable angina.As for lesion characteristics,diffuse disease was found in 91 case(26.1%),bifurcation lesions in 68 cases(19.6%),chronic total occlusion lesions in 56 cases(16.0%),in-stent restenosis in 14 cases and ostial lesions in 15 case.The immediate angiographic outcome,major cardiac event(MACE) and angiographic follow-up at 6 months were assessed.Results Stent implantation was successfully achieved in 99% patients with CHD.Acute and sub-acute stent thrombosis occurred in 2 patients,late stent thrombosis with AMI occurred in 2 patients,1 died during the 6 months follow-up.The MACE rate during hospitalization was 0.6% and 3.6% during 6 months follow-up.Angiographic follow-up in 84 patients at 6 months showed that in-stent restenosis rate(ISR)was 8.3%(restenosis within the stents was 2.4%).The target vessel revascularization(TLR)rate was 5.9%.Conclusions Cypher stent implantation in CHD is safe and effective,the ISR rate and TLR rate are significantly lower than those of bare metal stents.