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At least 613 records · Page 34Linked to original sources
PubMed2001

A pulsatile pneumatically driven neonatal extracorporeal membrane oxygenation system using neck vessel cannulas tested with neonatal mock circulation.

In posthypoxic circulatory failure, pulsatility of flow generated by mechanical support devices significantly influences outcome. Pneumatically driven assist devices can create highly pulsatile flow, but need large graft cannulas implanted by thoracotomy in children and neonates. Emergency application is therefore hindered. We conducted an in vitro study using neonatal mock circulation (NMC) to test whether an extracorporeal membrane oxygenation (ECMO) system driven by a commercially available pneumatic assist device also can be operated through commonly used neonatal neck vessel cannulas. Using the pneumatically operated Medos ventricular assist device (VAD) 10 ml ventricle along with the Jostra M8/HEC40 oxygenator/heat exchanger, a neonatal ECMO system was assembled and connected to the NMC by means of commercially available neonatal neck vessel cannulas. Effective ECMO flow, combined circulation flow, and circulation pressures were measured during various working settings (ventricle driving pressures [systolic/diastolic (mbar)]: low: +100/-25, moderate: +200/-50, high: +300/-99) and loading conditions (device working against 0, 50, and 100% native circulation flow). Additionally, maximum possible ECMO flow through various sizes of neonatal ECMO cannulas and resulting pressure gradients were assessed. High pressure settings were necessary to achieve 100 ml/kg/min pulsatile circulation flow in case of zero native circulation. With residual 30% native circulation flow, 100 ml/kg/min pulsatile circulation flow could be established by moderate pressure settings. Low preload or high systemic vascular resistance reduced ECMO flow markedly. We concluded that in the described setting a pneumatically driven neonatal ECMO system could be operated even through commonly used neonatal neck vessel cannulas. It was necessary to accept partial emptying of the artificial ventricle and tapering of driving pressures with increasing native circulation.

Blood Pressure↗
PubMed1997

Circulating activated endothelial cells in sickle cell anemia.

BACKGROUND: The vascular wall participates in the pathogenesis of sickle cell disease. To determine whether the endothelium is activated in this disease, we studied the number, origin, and surface phenotype of circulating endothelial cells in patients with sickle cell anemia. METHODS: We used immunohistochemical examination of buffy-coat smears to enumerate circulating endothelial cells, and we evaluated the surface phenotype by applying preparations of circulating endothelial cells. An immunofluorescence microscopy panel of antibodies was used, including a specific anti-endothelial-cell antibody, P1H12. RESULTS: Mean (+/-SD) numbers of circulating endothelial cells in normal blood donors, patients with sickle cell trait, and patients with hemolytic anemias not due to hemoglobin S were 2.6+/-1.6, 3.0+/-2.6, and 2.0+/-0.8 per milliliter of whole blood, respectively. Patients with sickle cell anemia who presented with acute painful episodes had 22.8+/-18.2 circulating endothelial cells per milliliter of blood (P<0.001 for the comparison with normal donors), and patients with no such events within one month before or after blood sampling had 13.2+/-11.8 circulating endothelial cells per milliliter of blood (P=0.002 for the comparison with normal donors and P=0.019 for the comparison with patients with acute events). Serial observations of three patients showed a tendency toward higher levels of circulating endothelial cells at the onset of acute painful crises. The average viability of circulating endothelial cells was 66+/-30 percent. In patients with sickle cell anemia, regardless of clinical status, the circulating endothelial cells were predominantly microvascular in origin (CD36-positive), and most of the cells expressed four markers of endothelial-cell activation: intercellular adhesion molecule 1, vascular-cell adhesion molecule 1, E-selectin, and P-selectin. CONCLUSIONS: Our studies suggest that the vascular endothelium is activated in patients with sickle cell anemia, regardless of the patients' clinical status. Adhesion proteins on activated endothelial cells may have a role in the vascular pathology of sickle cell disease.

Adolescent↗
PubMed1992

Reduction in biliary IgA after burn injury. Role of diminished delivery via the thoracic duct and of enhanced loss from the systemic circulation.

The concentration of biliary IgA is greatly reduced after scald burn injury in the rat, thereby contributing to a deficiency in upper intestinal immune defense. This reduction in biliary IgA might have several explanations, including failure of the transhepatic transport of polymeric IgA (pIgA) from the circulation, decreased delivery of pIgA to the hepatocyte, or decreased local synthesis of IgA in the liver. The authors examined whether burn injury reduces circulating pIgA available for delivery to the hepatocyte. In initial studies, they demonstrated that burn injury induces a decrease in circulating pIgA in bile-duct-ligated rats. They then sought to determine whether this decrease in pIgA was due to increased loss from the circulation or to a decreased supply of pIgA to the circulation through the thoracic duct. After injection of purified 125I-pIgA into bile duct-ligated rats, radioactivity was removed more rapidly from the circulation of burn-injured compared with control rats. The radioactivity localized in the skin and muscle at the site of burn injury. In another group of rats with patent bile ducts, the thoracic duct was cannulated and lymph collected for 12 hours. The total amount of IgA protein in lymph was found to be reduced in burn-injured compared with control animals. Thus, burn injury is accompanied by reduced circulating pIgA, which may be attributed to its enhanced loss from the circulation and to decreased delivery of pIgA from the intestinal mucosa to the systemic circulation via the thoracic duct.

Animals↗
PubMed1992

The influence of lymphocyte counts and disease progression on circulating and inducible anti-HIV-1 cytotoxic T-cell activity in HIV-1-infected subjects.

OBJECTIVE: To evaluate specific anti-HIV cytotoxic T-lymphocyte (CTL) activity in relation to basic clinical and laboratory parameters used to follow HIV infection. METHODS: Lymphocytes from HIV-1-infected subjects with different clinical and immunologic features of HIV infection were tested for circulating and inducible anti-HIV CTL activity using autologous B-lymphoblastoid cells infected with recombinant vaccinia viruses expressing the HIV gag, pol and env genes as targets. Anti-HIV CTL were induced by stimulation with HIV-infected autologous lymphoblasts in vitro. RESULTS: We detected circulating anti-HIV CTL in asymptomatic subjects exclusively and found a significant association (P < 0.01) between CD8+ lymphocyte counts > or = 900/microliters blood and detectable levels of circulating anti-HIV CTL. Subjects with circulating anti-HIV CTL also had a higher mean CD8+ lymphocyte count than those without detectable circulating activity (P < 0.001), but there was no significant difference in mean CD4+ lymphocyte count. CD8+ human histocompatibility leukocyte antigen (HLA) class I-restricted anti-HIV CTL were induced in all HIV-infected subjects tested following stimulation with HIV-infected autologous lymphoblasts in vitro. In subjects without detectable circulating anti-HIV CTL, circulating HLA-DR+ cells contributed to anti-HIV CTL activity induced by stimulation with HIV or concanavalin A in vitro. CONCLUSIONS: Circulating anti-HIV CTL activity is associated with CD8+ lymphocyte counts > or = 900/microliters. Anti-HIV CTL retain proliferative and functional capacity following in vitro stimulation with HIV and interleukin-2 through all stages of HIV infection. Persistent inducible anti-HIV CTL activity in subjects with advanced HIV disease and without circulating CTL suggests impaired activation and/or proliferation of the CTL in vivo.

CD4-Positive T-Lymphocytes↗
PubMed2005

Comparison of bacterial populations and chemical composition of dairy wastewater held in circulated and stagnant lagoons.

AIMS: This study compared the chemical, physical and bacterial composition of circulated and stagnant dairy wastewaters. METHODS AND RESULTS: Samples taken from circulated and stagnant wastewater lagoons, over a 1-year period, were analysed for 10 chemical (total N, NH3, NO3, NO2, Na, Ca, HCO3, Fe, P and K) and six physical (biological oxygen demand, chemical oxygen demand, dissolved solids, electrical conductivity, pH and sodium absorption ratio) parameters and were found to be similar. The 16S rDNA genes from the samples were amplified, cloned and BLAST analysed. In total, 996 stagnant and 1052 circulated wastewater derived sequences were obtained, comprising 294 and 362 operational taxonomic units (OTUs) from the circulated and stagnant wastewaters respectively. Coverage estimates of the OTUs identified were 72.1% for the stagnant, and 63.6% for the circulated wastewater libraries. The greatest difference between the two wastewaters was a c. sixfold greater number of sequences representative of the family Chromatiaceae in the circulated wastewater derived library and a c. fivefold greater number of sequences representative of the phylum Chloroflexi in the stagnant wastewater derived library. CONCLUSIONS: Circulation of dairy wastewater does not affect any of the chemical or physical parameters tested; however, circulation does alter the bacterial community structure. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides evidence that circulation of dairy wastewater promotes the growth of bacteria within the family Chromatiaceae and that stagnant systems promote the growth of the phylum Chloroflexi.

Absorption↗
PubMed2005

Circulating endothelial cells are associated with future vascular events in hemodialysis patients.

BACKGROUND: Endothelial dysfunction and injury are thought to have a key role in the pathogenesis of cardiovascular disease. We hypothesized that the presence of circulating endothelial cells, as a reflection of ongoing endothelial injury, might provide a novel means for predicting cardiovascular events in hemodialysis subjects who are known to be at marked increased risk for cardiovascular disease. METHODS: Circulating endothelial cell number was determined in 29 hemodialysis patients who were then followed for vascular events for 470 +/- 172 days. In a second cohort of 44 hemodialysis patients, circulating endothelial cell number was correlated with markers of inflammation, namely high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, IL-10, and monocyte chemoattractant protein-1 (MCP-1), and endothelial dysfunction, soluble vascular cellular adhesion molecule-1 (VCAM-1). RESULTS: Seven of the 19 subjects with elevated circulating endothelial cells (defined as >19 cells per mL) had cardiovascular (N= 5) or vascular (N= 5) events during follow-up, whereas no events occurred in subjects with a low number of circulating endothelial cells (</=19 CECs per mL) (P= 0.04 by Fisher Exact Test). In the second cohort, the number of circulating endothelial cells was independent of all markers of inflammation and endothelial dysfunction. CONCLUSION: In this hemodialysis population, an increase in circulating endothelial cells was found to predict the development of cardiovascular and vascular events, and to be independent of other known markers of inflammation or endothelial dysfunction. These studies suggest that circulating endothelial cells may be a novel way to assess endothelial health and cardiovascular risk. Further studies to investigate the utility of circulating endothelial cells in predicting cardiovascular risk are needed.

Adult↗
PubMed2002

Circulating peripheral blood plasma cells as a prognostic indicator in patients with primary systemic amyloidosis.

This study examined the prognostic value of circulating peripheral blood plasma cells (PBPCs) in patients with primary systemic amyloidosis (AL). A sensitive slide-based immunofluorescence technique was used to assess 147 patients for circulating PBPCs. Circulating monoclonal plasma cells were quantified as a percentage of circulating cytoplasmic immunoglobulin-positive cells (PBPC%). The absolute circulating plasma cell count was also determined. When analyzed retrospectively, 24 (16%) of 147 patients were found to have detectable circulating PBPCs. Overall survival for patients with high PBPC%'s (> 1%) was poorer (median survival, 10 vs 29 months; P =.002). Similarly, overall survival for patients with high PBPC counts (> 0.5 x 10(6)/L) was significantly poorer (median, 13 vs 31 months; P =.003). Increased percentages of bone marrow plasma cells (BMPC%; P =.0004), increased levels of serum beta(2)-microglobulin (P =.04), and dominant cardiac amyloid involvement (P =.03) also predicted poorer survival. The combined consideration of circulating PBPCs and BMPC% identified low-, intermediate-, and high-risk groups with median survivals of 37.5, 15.5, and 10 months, respectively (P =.0003). Multivariate analysis revealed circulating PBPCs and BMPC% to be independent prognostic factors for survival. Patients with PBPC%'s of 2% or higher were significantly more likely to have a coexisting clinical diagnosis of multiple myeloma (50% vs 12%, P =.008). The prognostic value of circulating PBPCs may help select treatment for patients with AL.

Adult↗
PubMed2005

Prognostic value of circulating plasma cells in monoclonal gammopathy of undetermined significance.

PURPOSE: Monoclonal gammopathy of undetermined significance (MGUS) progresses to multiple myeloma or another related plasma cell disorder (PCD) at a rate of approximately 1% per year. Identification of patients with MGUS at high risk of progression will allow development of preventive strategies. We studied the prognostic value of circulating plasma cells (PCs) in patients with MGUS to predict progression. PATIENTS AND METHODS: Patients were eligible for this retrospective analysis if they were seen at the Mayo Clinic between 1984 and 1997, were diagnosed with MGUS, and had an analysis of the peripheral blood for circulating PCs by the slide-based immunofluorescence method. Patients were observed for progression to another PCD. RESULTS: Three hundred twenty-five patients were eligible and 63 (19%) had circulating PCs. Patients with circulating PCs were twice as likely (hazard ratio, 2.1) to experience progression to another PCD (most commonly myeloma), compared with those without circulating PCs (95% CI, 1.1 to 4.3; P = .03). In patients with circulating PCs, the median progression-free survival was 138 months compared with a median not yet reached for those without circulating PCs (P = .028). The median overall survival also was shorter for those with circulating PCs. Other factors with prognostic value were high levels of M protein and non-immunoglobulin G heavy-chain type. CONCLUSION: The presence of circulating PCs, especially when combined with other known prognostic factors such as M protein concentration and immunoglobulin isotype, identify a group of individuals with MGUS at higher risk of progression to overt multiple myeloma.

Adolescent↗
PubMed1995

Circulating intercellular adhesion molecule-1(ICAM-1) in sera of patients with Graves' disease and Hashimoto disease.

OBJECTIVES: Intercellular adhesion molecule-1 (ICAM-1), a 80-110 kD glycoprotein, has been found to be a ligand for the lymphocyte function associated antigen-1 (LFA-1) molecule and has important roles in inflammatory and immune mediated mechanisms. ICAM-1 is expressed on thyroid follicular cells of patients with Hashimoto disease and cultured thyroid monolayer cells derived from the thyroid surgical specimen. In addition to the expression of ICAM-1 on the surface of cells, soluble variants of several adhesion molecules have been reported. METHODS: We evaluated the circulating ICAM-1 in sera of representative autoimmune thyroid disease, Hashimoto and Graves' disease, and analyzed correlations between circulating ICAM-1 and thyroid-directed autoantibodies. Sera were collected from 58 patients with autoimmune thyroid disease, 28 patients with Graves' disease and 30 patients with Hashimoto disease. Serum concentrations for circulating ICAM-1 were determined with sandwitch enzyme immunoassay. RESULTS: Compared with normal individuals, mean serum concentrations for circulating ICAM-1 were significantly elevated in patients with Hashimoto disease and antithyroperoxidase-positive Graves' disease. Patients with antithyroperoxidase-positive Graves' disease revealed significantly higher serum circulating ICAM-1 concentrations than antithyroperoxidase-negative Graves' disease. Circulating ICAM-1 showed significant positive correlation with serum titers of antithyroglobulin and antithyroperoxidase antibody (r = 0.44, n = 28, p = 0.009, and r = 0.55, n = 28, p = 0.001 respectively). There was a significant positive correlation between circulating ICAM-1 levels and serum antithyroperoxidase level in the group of autoimmune thyroid disease and also circulating ICAM-1 levels were significantly correlated with serum antithyroperoxidase antibody levels in antithyroperoxidase antibody-positive Graves' disease(r = 0.55, n = 28, p = 0.001) and in Hashimoto disease (r = 0.5, n = 30, p = 0.002). The thyrotropin binding inhibiting immunoglobulins(TBII) showed no significant correlation with circulating ICAM-1 levels. CONCLUSIONS: In the present study, high serum levels of ICAM-1 were associated with autoimmune thyroid disease. Graves' disease and Hashimoto disease and positively correlates with levels of antithyroperoxidase antibody.

Autoantibodies↗
PubMed2006

Circulating progenitor epithelial cells traffic via CXCR4/CXCL12 in response to airway injury.

Recipient airway epithelial cells are found in human sex-mismatched lung transplants, implying that circulating progenitor epithelial cells contribute to the repair of the airway epithelium. Markers of circulating progenitor epithelial cells and mechanisms for their trafficking remain to be elucidated. We demonstrate that a population of progenitor epithelial cells exists in the bone marrow and the circulation of mice that is positive for the early epithelial marker cytokeratin 5 (CK5) and the chemokine receptor CXCR4. We used a mouse model of sex-mismatched tracheal transplantation and found that CK5+ circulating progenitor epithelial cells contribute to re-epithelialization of the airway and re-establishment of the pseudostratified epithelium. The presence of CXCL12 in tracheal transplants provided a mechanism for CXCR4+ circulating progenitor epithelial cell recruitment to the airway. Depletion of CXCL12 resulted in the epithelium defaulting to squamous metaplasia, which was derived solely from the resident tissue progenitor epithelial cells. Our findings demonstrate that CK5+CXCR4+ cells are markers of circulating progenitor epithelial cells in the bone marrow and circulation and that CXCR4/CXCL12-mediated recruitment of circulating progenitor epithelial cells is necessary for the re-establishment of a normal pseudostratified epithelium after airway injury. These findings support a novel paradigm for the development of squamous metaplasia of the airway epithelium and for developing therapeutic strategies for circulating progenitor epithelial cells in airway diseases.

Animals↗
PubMed1992

[The concentration of atrial natriuretic peptides (ANP). ANP in different sections of the circulation during atrial volume load with and without anesthesia].

We studied the effect of a volume load induced by a 45 degrees Trendelenburg position on atrial natriuretic peptide (ANP) secretion in awake and anaesthetized patients with coronary artery disease undergoing aortocoronary bypass surgery. ANP was measured in different parts of the circulation before and after induction of high dose fentanyl anaesthesia at fixed times prior to and after extracorporeal circulation. METHOD. In eight patients with coronary artery disease (NYHA classification II-III), who received neither diuretic nor positive inotropic therapy, ANP was measured in the various parts of the circulation: in a peripheral vein, a radial artery, in the pulmonary artery and in the coronary sinus. The measurements were made in the supine and 45 degrees Trendelenburg position. Measurements of mean arterial pressure (MAP), central venous pressure (RAP), pulmonary arterial pressure (PAP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI) and heart rate (HR) were taken simultaneously. The measurements were taken in the awake patient, during steady-state high-dose fentanyl anaesthesia with 50% O2 in N2O and after extracorporeal circulation. RESULTS. Compared to measurements in a control group, ANP levels were significantly higher in all parts of the circulation in patients with coronary artery disease, although clinical symptoms of heart failure were absent. After extracorporeal circulation, significantly higher levels of ANP were found at all measurement sites; however the concentration gradient of ANP between coronary sinus and arterial or venous blood was reduced. In awake and anaesthetized patients a change in body position, causing a significant increase in filling pressures, did not produce an increase in ANP levels at all measurement sites. The induction of high-dose fentanyl anaesthesia did not have an influence on plasmatic ANP levels. CONCLUSION. The results of this study lead to the following conclusions: 1. ANP levels in patients with CAD are increased, even if clinical heart failure symptoms are absent. 2. ANP is secreted in the coronary vessels. Following dilution in the atrial blood, it is metabolized to inactive compounds in the periphery. 3. Basic ANP levels are not changed by high-dose fentanyl anaesthesia. Marked increases of the filling pressures do not correlate with atrial ANP levels either before or after induction of anaesthesia. 4. After extracorporeal circulation ANP levels are significantly increased in all parts of the circulation. The concentration gradient between coronary sinus blood, on the one hand, and arterial and venous blood on the other hand is reduced. This phenomenon is probably caused by an alteration in the metabolism of ANP during hypothermic extracorporeal circulation.

Aged↗
PubMed2006

Lymph circulation in the breast after radiotherapy and breast conservation.

The aim of this study was to investigate the breast lymph circulation and skin blood circulation after radiotherapy and breast conservation. In 23 patients who had undergone lumpectomy for breast cancer (mean age 58 years, range 44-75) and 12 patients with lumpectomy for benign lesions (mean age 51 years, range 33-72), lymph circulation in the breast was measured by 99mTc-nanocolloid clearance and skin circulation by Laser Doppler Fluxmetry (LDF). Measurements were made 2-5 years after radiotherapy (50 Gy) in the former group and at a corresponding time in the latter. The lymph circulation was measured 2 cm above and medial or lateral to the areolar border in the quadrant not operated on for carcinoma. Skin circulation was measured at corresponding sites. The lymph circulation expressed as the ratio of 99mTc-nanocolloid clearance in the operated irradiated to that in the non-operated (radiation 2-4 Gy) breast was 2.33 (2.66) (median, interquartile range) (p value 0.01) and the skin circulation ratio over the corresponding area was 0.92 (0.21). Corresponding ratios in the non-radiotherapy group were 2.07 (1.96) (p value 0.03) and 1.04 (0.18) respectively. Compared with the control breast (i.e., the non-operated non-irradiated breast), there was a 4-fold increase in lymph flow in the operated, irradiated breast, a 2.5-fold increase in the contralateral non-operated (2-4 Gy) breast and a 1.5-fold increase in the operated non-irradiated breast. Radiotherapy after breast conservation surgery leads to increased long-term changes in basal lymph circulation and smaller increases in lymph flow in the contralateral breast receiving 2-4 Gy and after surgery. If maximal lymph transport capacity is unchanged, edema may be more likely in this circumstance of reduced lymphatic transport reserve.

Adult↗
PubMed1980

Circulation versus photocopy: Quid pro Quo?

Information thought necessary for assessing the potential impact of a limited journal circulation policy at the University of California, San Francisco, included the effects on seating, on in-house photocopying, and on circulation. An initial survey during a "typical circulation" week showed journal circulation to be 71% of the total, with journals issued during the past five years comprising 45% of the total. A survey of user photocopying practice suggested that circulation limited to journals more than five years old might result in a 90% increase in photocopying, and results of the circulation survey were used to predict a 45% decrease in circulation. Results of implementing a limited circulation policy were a 41% decrease in circulation and a 136% increase in photocopy. Differences between prediction and results may be accounted for by the effect of duplicate copy subscriptions and by provision of convenient photocopy facilities.

Copying Processes↗
PubMedDate not supplied

Serum levels of circulating intercellular adhesion molecule-1 in patients with breast cancer.

BACKGROUND: The outcome of breast cancer is usually determined by multiple factors. Circulating intercellular adhesion molecule-1 has been found to be increased in the circulation of patients with malignancy. This study was designed with the aim of evaluating the prognostic significance of circulating intercellular adhesion molecule-1 in breast cancer. METHODS AND MATERIAL: From December 1994 to May 1995, 50 patients with invasive breast carcinoma were included. Venous blood samples were collected before surgery and the serum levels of circulating intercellular adhesion molecule-1 were measured with an enzyme immunoassay method. The data of maximum tumor size, age, estrogen receptor status, lymph node status and TNM staging were collected and evaluated simultaneously with the serum levels of circulating intercellular adhesion molecule-1. Fifteen healthy subjects were used as control group. RESULTS: The mean value of circulating intercellular adhesion molecule-1 in patient group was 463 +/- 92 ng/ml and that of the control group was 346 +/- 68 ng/ml and the difference was significant (p < 0.01). In univariable analysis, patients with maximum tumor size of 5 cm or greater (p < 0.01), more advanced lymph node status (p < 0.01) and more advanced TNM staging (p < 0.01) were shown to have significantly higher serum levels of circulating intercellular adhesion molecule-1. However, in multivariable analysis, TNM staging was demonstrated to be the only independent factor (p < 0.01) related to significant, higher serum level of circulating intercellular adhesion molecule-1. CONCLUSION: Preoperative serum levels of circulating intercellular adhesion molecule-1 may reflect the severity of staging for invasive breast cancer and may be a promising, additive predictor which deserves further investigation.

Adult↗
PubMed2002

Fate of collateral circulation after successful coronary angioplasty of total occlusion assessed by coronary angiography and myocardial contrast echocardiography.

A well-developed collateral circulation is frequently observed in patients with total coronary occlusion. However, the fate of the collateral circulation after successful percutaneous transluminal coronary angioplasty (PTCA) has not been fully characterized. The purpose of this study was to compare the efficacy of coronary angiography and myocardial contrast echocardiography (MCE) in the evaluation of the collateral circulation after PTCA and to assess the temporal changes of the collateral circulation after successful PTCA of a totally occluded artery by using these 2 diagnostic methods. The study group was comprised of 20 consecutive patients (16 male, mean age 54 years) who underwent elective PTCA for total coronary occlusion. Coronary angiography was performed before, immediately after, and 24 hours after PTCA. MCE was also performed before, immediately after, and 24 hours after PTCA, by the intracoronary injection of sonicated radiographic contrast medium. According to the angiographic findings, the collateral circulation was graded on a scale of 0 to 3 as follows: 0 = no visible filling; 1 = collateral filling of side branches; 2 = partial collateral filling of the epicardial artery; 3 = complete filling of the epicardial artery. By MCE, myocardial perfusion by the collateral circulation was assessed by scoring the contrast pattern of collateral-dependent myocardial segments as follows: 0 = none; 0.5 = patchy or epicardial; 1 = homogeneous. The left anterior descending artery was occluded in 12 patients and the right coronary artery in 8 patients. Coronary angiographic collateral grades before PTCA were grade 2 in 5 patients and grade 3 in 15. PTCA with stenting was successfully performed in all patients without significant residual stenosis. Coronary angiography showed collateral circulation disappeared after PTCA in all patients. However, residual collateral perfusion was observed in 7 patients by MCE, performed immediately after PTCA (score 1 in 3 patients; score 0.5 in 4 patients). This residual collateral perfusion could be demonstrated even 24 hours after PTCA by MCE in 3 patients (all patients were 0.5 in myocardial perfusion score). In conclusion, successful PTCA with stenting of a totally occluded coronary artery leads to a disappearance of collateral vessels by coronary angiography in most of the patients. However, although angiographically not visible, coronary collateral circulation may persist even 24 hours after successful PTCA of a totally occluded artery demonstrated by MCE.

Adult↗
PubMed2004

Adaptation to mechanical load determines shape and properties of heart and circulation: the CircAdapt model.

With circulatory pathology, patient-specific simulation of hemodynamics is required to minimize invasiveness for diagnosis, treatment planning, and followup. We investigated the advantages of a smart combination of often already known hemodynamic principles. The CircAdapt model was designed to simulate beat-to-beat dynamics of the four-chamber heart with systemic and pulmonary circulation while incorporating a realistic relation between pressure-volume load and tissue mechanics and adaptation of tissues to mechanical load. Adaptation was modeled by rules, where a locally sensed signal results in a local action of the tissue. The applied rules were as follows: For blood vessel walls, 1) flow shear stress dilates the wall and 2) tensile stress thickens the wall; for myocardial tissue, 3) strain dilates the wall material, 4) larger maximum sarcomere length increases contractility, and 5) contractility increases wall mass. The circulation was composed of active and passive compliances and inertias. A realistic circulation developed by self-structuring through adaptation provided mean levels of systemic pressure and flow. Ability to simulate a wide variety of patient-specific circumstances was demonstrated by application of the same adaptation rules to the conditions of fetal circulation followed by a switch to the newborn circulation around birth. It was concluded that a few adaptation rules, directed to normalize mechanical load of the tissue, were sufficient to develop and maintain a realistic circulation automatically. Adaptation rules appear to be the key to reduce dramatically the number of input parameters for simulating circulation dynamics. The model may be used to simulate circulation pathology and to predict effects of treatment.

Adaptation, Physiological↗
PubMed1987

Upstream pressure for systemic to pulmonary flow from bronchial circulation in dogs.

Systemic to pulmonary flow from bronchial circulation, important in perfusing potentially ischemic regions distal to pulmonary vascular obstructions, depends on driving pressure between an upstream site in intrathoracic systemic arterial network and pulmonary vascular bed. The reported increase of pulmonary infarctions in heart failure may be due to a reduction of this driving pressure. We measured upstream element for driving pressure for systemic to pulmonary flow from bronchial circulation by raising pulmonary venous pressure (Ppv) until the systemic to pulmonary flow from bronchial circulation ceased. We assumed that this was the same as upstream pressure when there was flow. Systemic to pulmonary flow from bronchial circulation was measured in left lower lobes (LLL) of 21 anesthetized open-chest dogs from volume of blood that overflowed from pump-perfused (90-110 ml/min) pulmonary vascular circuit of LLL and was corrected by any changes of LLL fluid volume (wt). Systemic to pulmonary flow from bronchial circulation upstream pressure was linearly related to systemic arterial pressure (slope = 0.24, R = 0.845). Increasing Ppv caused a progressive reduction of systemic to pulmonary flow from bronchial circulation, which stopped when Ppv was 44 +/- 6 cmH2O and pulmonary arterial pressure was 46 +/- 7 cmH2O. A further increase in Ppv reversed systemic to pulmonary flow from bronchial circulation with blood flowing back into the dog. When net systemic to pulmonary flow from bronchial circulation by the overflow and weight change technique was zero a small bidirectional flow (3.7 +/- 2.9 ml.min-1 X 100 g dry lobe wt-1) was detected by dispersion of tagged red blood cells that had been injected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Perfusion reserve of coronary collateral circulation and its significance in the development of exercise-induced ischemia in patients with multivessel disease.

To assess the perfusion reserve of coronary collateral circulation, we analyzed exercise-stress tomographic thallium-201 myocardial images in 12 patients who had total occlusion in the right coronary artery (RCA) or left circumflex coronary artery (LCX) with well-developed collateral circulation and 90% stenosis in the left anterior descending coronary artery (LAD). In 6 of the 12 patients, the collateral circulation was non-jeopardized (group A). In the remaining 6 patients, the collateral circulation was jeopardized (group B). All 6 of the patients in group A had an exercise-induced decrease in thallium uptake in the segments supplied by the occluded RCA or LCX with collateral circulation, and 3 (50%) of these 6 also showed a decrease in thallium uptake in the segments supplied by the LAD. All 6 of the patients in group B also had an exercise-induced decrease in thallium uptake in the segments supplied by the occluded RCA or LCX with collateral circulation, but none showed a decrease in thallium uptake in the segments supplied by the LAD. In conclusion, the perfusion reserve of collateral circulation is equal to or less than 90% stenosis and myocardial ischemia occurs first in the collateralized segments during exercise in patients with jeopardized collateral circulation.

Adult↗