Adaptation of endothelial cells to shear stress under atheroprone conditions by modulating internalization of vascular endothelial cadherin and vinculin.

BACKGROUND: Endothelial cells play a pivotal role in cardiovascular physiology and pathology by providing a barrier to the bloodstream. In the current study, we investigated the phenotype and barrier function of endothelial cells in response to shear stress under pro-atherogenic conditions. METHODS: Endothelial cells were exposed to laminar shear stress (LSS) in a parallel-plate flow chamber containing oxidized low-density lipoprotein (oxLDL) in the perfusion solution, or remained static. We quantified the response of endothelial monolayers to LSS and oxLDL in terms of cell viability, barrier integrity, vascular endothelial cadherin (VE-cadherin) availability, focal adhesion (FA) remodeling, and monocyte-endothelial interactions. RESULTS: Our results showed that oxLDL stimulation and static conditions synergized to enhance endothelial barrier disruption. Under the same oxLDL challenge, the application of 25 dynes/cm2 LSS on the endothelial monolayer decreased the passage of fluorescein isothiocyanate (FITC)-dextran by 37.79%, increased transendothelial electrical resistance (TEER) by 24.97% compared with static cells (P<0.05), which was accompanied by reduced intercellular gap formation, relatively solid cell-substrate adhesion. Compared with static cells, endothelial cells exposed to both laminar flow and oxLDL had less small FAs, less monocyte adhesion and transmigration, and alleviated overexpression of VCAM-1 and MCP-1. Meanwhile, the oxLDL-induced internalization of VE-cadherin and vinculin were also attenuated by laminar flow, and this change was more pronounced at LSS of 25 dynes/cm2 than 5 dynes/cm2. CONCLUSIONS: Static conditions favor, whereas physiologically higher levels of LSS ameliorate endothelial barrier disruption under pro-atherogenic stress, which is related to the improved availability of VE-cadherin and vinculin on the cell surface.

Enhanced external counterpulsation inhibits endothelial apoptosis via modulation of BIRC2 and Apaf-1 genes in porcine hypercholesterolemia.

OBJECTIVES: Enhanced external counterpulsation (EECP) could improve endothelium-dependent vasodilatation of carotid artery and restore imbalance of nitric oxide and endothein-1 in patients with coronary artery disease. Our study was designed to test the hypothesis that long-term EECP may protect vascular endothelial cells from apoptosis by modifying apoptosis-related gene expression. METHODS: Eighteen male Yorkshire pigs were randomly assigned to three groups: usual diet (Normal), high cholesterol diet (HC) and high cholesterol diet plus EECP (HC+EECP). Vascular endothelial cells were isolated from the aortic endothelium and identified by CD31 staining and DiI-Ac-LDL reaction. Morphological changes were observed by both scanning and transmission electronic microscopes. TUNEL technique was applied to detect the apoptotic index of vascular endothelial cells. Two genes, Apaf-1 and BIRC2, were chosen for exploring the potential mechanisms of action at the molecular level. RESULTS: EECP brought a certain degree of alleviation from ultrastructural changes such as shrinking and blebbing of cytomembrane, marginalization, degeneration, and fragmentation of the nucleus. EECP also significantly reduced apoptotic indices while compared with that of control (177±12‰ vs. 237±23‰, P<0.05). The Apaf-1 expression at both protein and mRNA level in pigs of HC+EECP group was significantly decreased than those of the HC group (P<0.05), whereas the BIRC2 expression was significantly enhanced after EECP treatment, documented by immunostaining and semi-quantitative RT-PCR analysis, respectively (P<0.05). CONCLUSIONS: EECP could protect vascular endothelial cells from apoptosis, thereby delaying the progression of early atherosclerotic lesions possibly through transcriptional down-regulation of pro-apoptotic gene Apaf-1, and up-regulation of anti-apoptotic gene BIRC2.

The effect of enhanced external counterpulsation on C-reactive protein and flow-mediated dilation in porcine model of hypercholesterolaemia.

BACKGROUND: Lipid disorder causes vascular endothelial cell damage and contributes to the early development of dyslipidaemia-induced atherosclerosis. In vivo and in vitro, it has been found that increasing shear stress can improve endothelial function. Clinically, enhanced external counterpulsation (EECP) plays important roles in the treatment of coronary artery disease by promoting arterial shear stress. The present study aims to evaluate the effect of EECP on vascular endothelial function in porcine hypercholesterolaemic model. METHODS: Twenty-six hypercholesterolaemic pigs were equally divided into EECP group (HC-EECP group) and control group (HC group). Shear stress of a right forearm superficial artery was measured during EECP in comparison with the basal physiological status in the HC-EECP group. Endothelial-dependent flow-mediated vasodilation (FMD) was applied to assess endothelial function. Serum high-sensitivity C-reactive protein (hs-CRP) levels were measured at indicated time points. RESULTS: Endothelial shear stress was increased significantly during EECP treatment (P<0.001). Compared to HC group, hs-CRP decreased significantly by EECP at 18- and 36-h, respectively (P<0.05). FMD was improved significantly by EECP compared to that of HC group at 18 h (11.09 ± 5.63%) and at 36 h (11.42 ± 2.75%) post-EECP, P<0.05. Meanwhile, in animals of HC group, FMD was decreased from baseline 7.76 ± 3.70% to 6.75 ± 3.57% at 18 h and 5.07 ± 1.97% at 36 h, P<0.05. CONCLUSION: Long-term EECP can improve endothelial function partially by an increased endothelial shear stress in hypercholesterolaemic porcine model. This implies that long-term EECP can be used as a complementary therapeutic strategy to prevent atherosclerosis in hypercholesterolaemic patients.

[Study of sharing platform of web-based enhanced extracorporeal counterpulsation hemodynamic waveform data].

Enhanced extracorporeal counterpulsation (EECP) information consists of both text and hemodynamic waveform data. At present EECP text information has been successfully managed through Web browser, while the management and sharing of hemodynamic waveform data through Internet has not been solved yet. In order to manage EECP information completely, based on the in-depth analysis of EECP hemodynamic waveform file of digital imaging and communications in medicine (DICOM) format and its disadvantages in Internet sharing, we proposed the use of the extensible markup language (XML), which is currently the Internet popular data exchange standard, as the storage specification for the sharing of EECP waveform data. Then we designed a web-based sharing system of EECP hemodynamic waveform data via ASP. NET 2.0 platform. Meanwhile, we specifically introduced the four main system function modules and their implement methods, including DICOM to XML conversion module, EECP waveform data management module, retrieval and display of EECP waveform module and the security mechanism of the system.

[The compression and storage of enhanced external counterpulsation waveform based on DICOM standard].

The development of external counterpulsation (ECP) local area network system and extensible markup language (XML)-based remote ECP medical information system conformable to digital imaging and communications in medicine (DICOM) standard has been improving the digital interchangeablity and sharability of ECP data. However, the therapy process of ECP is a continuous and longtime supervision which builds a mass of waveform data. In order to reduce the storage space and improve the transmission efficiency, the waveform data with the normative format of ECP data files have to be compressed. In this article, we introduced the compression arithmetic of template matching and improved quick fitting of linear approximation distance thresholding (LADT) in combimation with the characters of enhanced external counterpulsation (EECP) waveform signal. The DICOM standard is used as the storage and transmission standard to make our system compatible with hospital information system. According to the rules of transfer syntaxes, we defined private transfer syntax for one-dimensional compressed waveform data and stored EECP data into a DICOM file. Testing result indicates that the compressed and normative data can be correctly transmitted and displayed between EECP workstations in our EECP laboratory.

Enhanced external counterpulsation attenuates atherosclerosis progression through modulation of proinflammatory signal pathway.

OBJECTIVE: Shear stress may be the most crucial local factor affecting atherogenesis. The present study investigated the effect of exposure to increased shear stress promoted by enhanced external counterpulsation (EECP) on the progression of atherosclerosis and the underlying inflammation-related molecular mechanisms in a porcine model of hypercholesterolemia. METHODS AND RESULTS: Hypercholesterolemic pigs were subjected to a 7-week EECP intervention while being fed a high-cholesterol diet. EECP resulted in a 34.38% increase of mean wall shear stress and a significantly lower pulsatility index in the brachial artery. The animals receiving EECP showed a marked reduction in atherosclerotic lesion size in the coronary artery and abdominal aorta compared with the hypercholesterolemic control group, associated with a decrease in macrophage accumulation. The expression of a set of genes involved in inflammation (including C-reactive protein [CRP], complement 3a, vascular cell adhesion molecule-1 [VCAM-1], and inducible nitric oxide synthase), mitogen-activated protein kinase (MAPK)-p38 phosphorylation, and nuclear factor-kappaB (NF-kappaB) activation, was attenuated. CONCLUSIONS: These findings suggested that long-term EECP exerts a retarding effect on atherosclerosis by downregulating proinflammatory gene expression. The underlying mechanisms are related to chronic exposure to increased pulsatile shear stress promoted by EECP; this exposure suppresses the overactivation of the MAPK-P38/NF-kappaB/VCAM-1 signaling pathway induced by hypercholesterolemia.

Enhanced external counterpulsation promotes growth cytokines-mediated myocardial angiogenesis in a porcine model of hypercholesterolemia.

BACKGROUND: 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(+). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Effect of external counterpulsation on morphological damage of endomembrane and endothelium-dependent vasodilatation in the carotid arteries in hypercholesterolemic pigs].

OBJECTIVE: To explore the effect of long-term enhanced external counterpulsation (EECP) on morphological damage of endomembrane and endothelium-dependent vasodilatation of the carotid arteries of hypercholesterolemic pigs. METHODS: Eighteen male infant pigs were randomly divided into three groups according to the contents of their diet: the normal control group (n=6), the high-cholesterol feeding control group (n=6) and EECP group (n=6). Porcine model of hypercholesterolemia was reproduced by feeding animals with high-cholesterol diet. After completion of EECP treatment for 36 hours in EECP group, carotid arterial rings were harvested from all animals. Both scanning and transmission electron microscopy was employed to observe the changes in morphology of their endomembrane. At the same time, their vasodilatation response to variant dose of acetylcholine (Ach) was detected. RESULTS: The surface of endothelium in the normal control group was smooth, and endothelial cells were in regular streamline array, and they were almost in same size, attaching closely to matrix without smooth muscle cell proliferation and lipid infiltration in intima. In contrast, the endothelial cells of hypercholesterolemic pigs were in irregular array, with marked desquamation, resulting in loose linkage. Smooth muscle cells were found to invade into intimal layer and proliferated, and foam cells could also be found in intimal layer. In hypercholesterolemic pigs treated with EECP, slight intimal damage was found. In addition, with Ach dose of 10(-8) mol/L to 10(-5)mol/L, endothelium-dependent vasodilatation ratio in hypercholesterolemic pigs with or without EECP treatment, was significantly lower than that of the normal control group (all P<0.05). However, endothelium-dependent vasodilatation ratio in pigs with EECP treatment was obviously higher compared with hypercholesterolemic pigs without EECP treatment with the dosage of Ach concentration ranged from 10(-7) mol/L to 10(-5) mol/L (all P<0.05). CONCLUSION: Long-term EECP ameliorates both the morphological damage and the impaired endothelium-dependent vasodilatation function resulting from hypercholesterolemia, contributing to prevention of atherosclerosis.

Enhanced external counterpulsation inhibits intimal hyperplasia by modifying shear stress responsive gene expression in hypercholesterolemic pigs.

BACKGROUND: Enhanced external counterpulsation (EECP) is a circulation assist device that may improve endothelial dysfunction by increasing shear stress. Chronic exposure of vascular endothelial cells and vascular smooth muscle cells to relatively high physiological shear stress has antiproliferative and vasoprotective effects. The present study hypothesizes that EECP inhibits intimal hyperplasia and atherogenesis by modifying shear stress-responsive gene expression. METHODS AND RESULTS: Thirty-five male pigs were randomly assigned to 3 groups: high-cholesterol diet (n=11), high-cholesterol diet plus EECP (n=17), and usual diet (control; n=7). The coronary arteries and aortas were collected for histopathological study and immunohistochemical and Western blot analysis. The peak diastolic arterial wall shear stress during EECP increased significantly compared with before EECP (49.62+/-10.71 versus 23.92+/-7.28 dyne/cm2; P<0.001). Intimal hyperplasia was observed in the coronary arteries of the high-cholesterol diet group, whereas in animals receiving EECP, the intima-to-media area ratio was significantly decreased by 41.59% (21.27+/-10.00% versus 36.41+/-16.69%; P=0.008). Hypercholesterolemia attenuated the protein expression of endothelial NO synthase and enhanced the phosphorylation of extracellular signal-regulated kinases 1/2. EECP treatment alleviated these adverse changes. CONCLUSIONS: EECP reduces hypercholesterolemia-induced endothelial damage, arrests vascular smooth muscle cell proliferation and migration, decreases proliferating cell nuclear antigen proliferative index, suppresses extracellular matrix formation, and eventually inhibits intimal hyperplasia and the development of atherosclerosis by increasing the arterial wall shear stress, which in turn activates the endothelial NO synthase/NO pathway and probably suppresses extracellular signal-regulated kinases 1/2 overactivation.

[Effects of external counterpulsation on shear stress and production of nitric oxide and cGMP in canines with myocardial infarction].

OBJECTIVE: To investigate the effects of external counterpulsation (ECP) on shear stress and signal transduction in canines with myocardial infarction. METHODS: Nineteen healthy dogs were randomly divided into control, ischemia, and ischemia plus ECP groups. Myocardial infarction was induced in the latter two groups by ligation of the left anterior descending artery (LAD). Serum and aorta NO levels of the dogs were determined by modified nitrate reductase method, and serum and aorta cyclic guanosine monophosphate (cGMP) levels by radioimmunoassay. RESULTS: The shear stress in the truncus brachiocephalicus decreased after LAD ligation, but increased significantly after 2 h of ECP treatment. Serum and aorta NO levels in ECP and control groups were significantly higher than those in the ischemic group (P<0.05). Serum and aorta cGMP levels in control group and ECP group after LAD ligation were also significantly higher than those in the ischemic group (P<0.05). CONCLUSION: ECP can increase the shear stress and increase NO and cGMP levels in dogs with myocardial ischemia, which might be an important mechanism of ECP for protection of the ischemic myocardium.

[Establishment of a pig model of chronic ally enhanced external counterpulsation].

OBJECTIVE: To establish a pig model of chronic external counterpulsation. METHODS: Twelve pigs were anaesthetized with sodium pentobarbital (< or =30 mg/kg.b.w.) and 846 mixture (< or =0.1 ml/kg.b.w.) and counterpulsed in a lateral position for 2 h every two days (totally 36 h) with 0.025 to 0.04 MPa/cm(2) pressure. RESULTS: External counterpulsation was successfully completed in all the animals. Combined administration of sodium pentobarbital and 846 mixture resulted in good anesthetic effect with reduced anesthetic dosage and minimal side effect on the viscera (the liver, kidney and heart, etc). CONCLUSION: The pig model of chronic external counterpulsation has been successfully established. Combined use of sodium pentobarbital and 846 mixture is recommended for chronic external counterpulsation.

Effect of external counterpulsation on plasma nitric oxide and endothelin-1 levels.

Enhanced external counterpulsation (EECP) significantly augments diastolic blood flow and has been postulated to improve endothelial function by increased shear stress. We examined the effects of EECP on plasma nitric oxide and endothelin-1 (ET-1) levels. Plasma nitrate and nitrite (NOx) and ET-1 levels were measured serially in 13 patients with coronary artery disease who received 1-hour daily treatments of EECP over 6 weeks. During the course of EECP therapy, plasma NOx progressively increased and plasma ET-1 progressively decreased. After 36 hours of EECP, there was a 62 +/- 17% increase in plasma NOx compared with baseline (43.6 +/- 4.3 vs 27.1 +/- 2.6 micromol/L, p <0.0001) and a 36 +/- 8% decrease in plasma ET-1 (76.7 +/- 9.5 vs 119.5 +/- 8.5 pg/L, p <0.0001). At 3 months after completion of EECP, NOx remained 12 +/- 11% above baseline (p = 0.002), and ET-1 remained 11 +/- 10% below baseline (p = 0.0068). Our data provides neurohormonal evidence to support the hypothesis that EECP improves endothelial function.

[Effects of enhanced external counterpulsation in atherosclerosis and NF-kappaB expression: a pig model with hypercholesterolemia].

OBJECTIVE: To study the effects of enhanced external counterpulsation (EECP) on the vascular morphology, and endothelial function using experimentally induced hypercholesterolemic pigs. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Angiogenic effects of long-term enhanced external counterpulsation in a dog model of myocardial infarction.

Enhanced external counterpulsation (EECP) is an effective noninvasive treatment of coronary artery disease. Its mechanism of action remains unknown. An acute coronary occlusion dog model was created to explore the angiogenic effect of EECP. After coronary occlusion, 12 dogs were randomly assigned to either EECP (n = 6) or control (n = 6). 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 ELISA and reverse transcriptase PCR analysis. There was a significant increase in the density of microvessels per squared millimeter in the infarcted regions of the EECP group compared with the control group (vWF, 15.2 +/- 6.3 vs. 4.9 +/- 2.1, P < 0.05; alpha-actin, 11.8 +/- 5.3 vs. 3.4 +/- 1.2, P < 0.05). The positive-stained area per squared micrometer also increased significantly (alpha-actin, 6.6 x 10(3) +/- 2.9 x 10(3) microm2 vs. 0.6 x 10(3) +/- 0.5 x 10(3) microm2, P < 0.05; vWF, 5.7 x 10(3) +/- 1.9 x 10(3) microm2 vs. 1.7 x 10(3) +/- 1.4 x 10(3) microm2, P < 0.05). Immunohistochemical staining and reverse transcriptase 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. Angiogenesis may be a mechanism of action for the improved myocardial perfusion demonstrated after EECP therapy.

[Effect of chronic enhanced external counterpulsation on arterial endothelial cells of porcine with hypercholesteremia].

OBJECTIVE: To verify whether chronic enhanced external counterpulsation (EECP) may repair artery endothelial cells (ECs) damage resulted from hypercholesteremia in pigs. METHODS: EECP was performed for 36 hours in pigs with hypercholesteremia and the left descending artery (LDA) was isolated for scanning electron microscopy (SEM). The ECs were collected from the thoracic aorta and analyzed by proteomic technique. RESULTS: The ECs of hypercholesteremia pigs showed irregular arrangement with obvious desquamation of coronary ECs and formation of atherosclerotic plaque, and these lesions were milder in EECP-treated pigs. Six over-expressed proteins were detected in the endothelial cells in EECP-treated pigs in comparison with those of the hypercholesteremia pigs. CONCLUSION: Chronic EECP helps restore cell morphology and repair functional damage of ECs resulted from hypercholesteremia by regulating endothelial protein expressions, and consequently improves cell adhesion and intracellular metabolism and reduces EC apoptosis.

Microvessel angiogenesis: a possible cardioprotective mechanism of external counterpulsation for canine myocardial infarction.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: Microvessel angiogenesis may be a mechanism of action for the improved myocardial perfusion after EECP therapy.

[Effects of external counterpulsation on the pulsatility of blood pressure and blood flow in dogs].

Pulsatile blood flow plays an important role in maintaining normal vascular endothelial function. Quantitative measurement of pulsatility of artery blood pressure and blood flow in dogs and effects of enhanced external counterpulsation (EECP) on the pulsatility were taken in this study. Common carotid artery blood pressure and blood flow were measured in 6 beagle dogs that had suffered from an acute myocardial infarction 6 weeks before. A 6F tip transducer catheter was inserted into the right common carotid artery to measure blood pressure, and blood flow was measured in the left common carotid artery by an electromagnetic blood flow probe under anesthesia before and during EECP. Blood pulse pressure, pulsatility index (ratio of peak pressure to end diastolic pressure) and standard deviation of blood pressure were calculated to evaluate the pulsatility of arterial blood pressure. Blood pulse flow, pulsatility index (ratio of peak flow to trough flow) and standard deviation of blood flow were calculated to evaluate the pulsatility of blood flow. Mean vascular resistance (MVR) was calculated as MVR = mean blood pressure/mean blood flow. Blood pulse pressure, pulsatility index and standard deviation of blood pressure were elevated from 30 +/- 9 mmHg, 1.26 +/- 0.05 and 8.7 +/- 2.5 mmHg to 43 +/- 8 mmHg (P < 0.05), 1.54 +/- 0.13 and 12.4 +/- 2.0 mmHg (P < 0.05) before and during EECP, respectively. Blood pulse flow, pulsatility index and standard deviation of blood flow were elevated from 317 +/- 48 ml/min, 2.85 +/- 0.21 and 96 +/- 21 ml/min to 447 +/- 88 ml/min, 4.56 +/- 0.90 and 131 +/- 39 ml/min before and during EECP (P < 0.05). MVR was decreased from 578 +/- 72 before EECP to 476 +/- 85 Wood units during EECP(P < 0.05). These data demonstrate that EECP gives an elevation of pulsatility to blood pressure and blood flow, thus it may lead to the decrease of vascular resistance.

[Effects of external counterpulsation on the pulsatility of blood pressure in human subjects].

Pulsatile blood flow plays an important role in maintaining normal vascular endothelial function. Quantitative measurement of pulsatility of human arterial blood pressure and the influence of enhanced external counterpulsation (EECP) on the pulsatility were investigated in this study. Eight healthy young male volunteers aged 22 to 35 were included. A 4F tip transducer catheter was inserted under local anaesthesia into the radial artery up to the aortic arch. Intraarterial blood pressure was recorded before and during EECP. Blood pulse pressure, pulsatility index (ratio of peak pressure to end diastolic pressure) and standard deviation of blood pressure in 5 cardiac cycle was calculated to evaluate the pulsatility of arterial blood pressure. The results showed that blood pulse pressure, pulsatility index and standard deviation of blood pressure were elevated from 47 +/- 5 mmHg, 1.64 +/- 0.11 and 13.6 +/- 1.5 mmHg to 77 +/- 3 mmHg, 2.46 +/- 0.25 and 19.3 +/- 2.2 mmHg before and during EECP respectively (P < 0.05). Decreasing of systolic pressure and increasing of diastolic pressure during counterpulsation were also observed. EECP gives an elevation of pulsatility to human blood pressure.