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Coronary Circulation (coronary + circulation)
Selected AbstractsNoninvasive Assessment of Coronary Flow Reserve in the Left Anterior Descending Artery by Transthoracic Echocardiography before and after StentingECHOCARDIOGRAPHY, Issue 8 2007Elie Chammas M.D., F.E.S.C. Background: Noninvasive assessment of coronary flow reserve in the left anterior descending artery (LAD) by transthoracic Doppler echocardiography (TTDE) has been already validated as a new method for determining the degree of stenosis over the proximal flow. Objectives: The aim of the study is to determine, by TTDE, the feasibility and the value of the coronary flow reserve (CFR) (defined as the maximal increase in coronary blood flow above its basal pressure for a given perfusion pressure when coronary circulation is maximally dilated) in the mid-to-distal LAD before and after percutaneous angioplasty and to demonstrate the early recovery of microvascular tone immediately after stenting. Methods: The study population consisted of 36 patients with significant isolated LAD stenosis (70,90%) identified by coronary angiography. CFR was recorded in the mid-to-distal LAD at rest and during hyperemia obtained after adenosine intravenous infusion before and after stenting. Results: Adequate visualization of the LAD was obtained in 25 out of 36 patients (70%). At rest the mean CFR was 1.5132 ± 0.33 (1.1,2.58). However, after stenting the mean CFR was significantly higher: 2.18 ± 0.55 (1.3,3.8), with P <0.01. Conclusions: CFR can be easily determined by TTE in approximately 70% of patients. Noninvasive Doppler echocardiography shows impaired CFR in patients with LAD disease. After stenting CFR is restored, demonstrating early recovery of microvascular tone. These results are comparable to those published in the same conditions. Larger series with a long-term follow-up may allow identifying patients at high risk for restenosis after stenting. [source] Oestrogen attenuates coronary vasoconstriction after angioplasty: role of endothelin-1EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2002T-M. Lee Abstract Background and aims There were controversies as to whether endothelin-1 is released after coronary angioplasty. We sought to determine whether endothelin-1 is released after coronary angioplasty and whether oestrogen administration can affect coronary vasomotor tone by reducing endothelin-1 concentrations. Methods The study was designed to prospectively investigate 24 consecutive patients scheduled for elective coronary angioplasty. Patients were randomized into two groups according to whether they did not (group 1, n = 12) or did (group 2, n = 12) have intracoronary treatment with oestrogen. Quantitative coronary angiography was monitored at baseline, immediately after successful angioplasty, and 15 min after the last deflation. Blood samples for measuring the levels of endothelin-1 were drawn from the ascending aorta and the coronary sinus simultaneously before angioplasty and 15 min after balloon dilatation. Results The diameters of the coronary artery at the dilated segments were significantly reduced 15 min after dilation compared with those immediately after dilation in group 1 from 3·20 ± 0·22 to 2·30 ± 0·23 mm (P < 0·001), respectively. The vasoconstriction was significantly blunted in group 2. The endothelin-1 levels from the coronary sinus rose significantly, by 29%, 15 min after angioplasty in group 1, which was attenuated after administering oestrogen. Significant correlation was found between the changes of coronary vasomotion of the dilated segment and endothelin-1 levels (r = 0·70, P = 0·01). Conclusion Endothelin-1 is released into the coronary circulation after angioplasty, and this vasoactive substance may contribute to the occurrence of vasoconstriction. The vasoconstriction is attenuated by oestrogen by reducing the endothelin-1 levels. This finding provided a new strategy to treat coronary vasoconstriction after angioplasty. [source] The Effect of Progesterone on Coronary Blood Flow in Anaesthetized PigsEXPERIMENTAL PHYSIOLOGY, Issue 1 2001C. Molinari The present study was designed to investigate the effect of progesterone on the coronary circulation and to determine the mechanisms involved. In pigs anaesthetized with sodium pentobarbitone, changes in left circumflex or anterior descending coronary blood flow caused by intravenous infusion of progesterone at constant heart rate and arterial blood pressure were assessed using an electromagnetic flowmeter. In 14 pigs, infusion of 1 mg h,1 of progesterone caused an increase in coronary blood flow without affecting left ventricular dP/dtmax (rate of change of left ventricular systolic pressure) and filling pressures of the heart. In a further four pigs, this vasodilatory coronary effect was enhanced by graded increases in the dose of the hormone of between 1, 2 and 3 mg h,1. The mechanisms of the above response were studied in the 14 pigs by repeating the experiment after haemodynamic variables had returned to the control values observed before infusion. In six pigs, blockade of muscarinic cholinoceptors and adrenoceptors with atropine, propranolol and phentolamine did not affect the coronary vasodilatation caused by progesterone. In the remaining eight pigs, this response was abolished by intracoronary injection of N, -nitro-L-arginine methyl ester (L-NAME) even when performed after reversing the increase in arterial blood pressure and coronary vascular resistance caused by L-NAME with continuous intravenous infusion of papaverine. The present study showed that intravenous infusion of progesterone primarily caused coronary vasodilatation. The mechanism of this response was shown to involve the endothelial release of nitric oxide. [source] Clinical methods for the evaluation of endothelial function , a focus on resistance arteriesFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 3 2006Robinson Joannides Abstract Endothelial dysfunction is a key event in the pathophysiology of cardiovascular diseases and appears as a strong independent predictor of cardiovascular events. In this context, biological evaluation of endothelial circulating markers can be helpful. However, functional tests using pharmacological stimuli appear more specific for the study of resistance arteries. These methods consist in the evaluation of the endothelium-dependent changes in regional vascular flow in response to local infusion of substances that act through endothelial receptors without modification of systemic arterial pressure and in comparison with a non endothelium-dependent relaxation. Flow is measured by Doppler and intravascular ultrasound in coronary circulation, laser Doppler in skin and by venous occlusion plethysmography in peripheral muscular arteries. Similar studies can be performed ex vivo using isolated resistance arteries obtained from fat subcutaneous biopsies. In addition, other information can be obtained from reactive hyperemia and the study of the flow-mediated dilatation of conduit arteries to enable a selective and comprehensive approach of the heterogeneity of endothelial function in pathophysiology. [source] Myocardial Failure Caused by Traumatic Dissection of Left Coronary System,Ventricular Recovery with Temporary Circulatory SupportJOURNAL OF CARDIAC SURGERY, Issue 3 2007Alexander Lauten M.D. The dissection involved the left coronary artery including peripheral segments of the coronary circulation. The patient was revascularized; however, she could not be weaned from cardiopulmonary bypass thereafter. An Impella microaxial hemopump was implanted and the patient's left ventricular function markedly improved during the following days. Eight days later hemodynamics had stabilized far enough to explant the device, after explantation the patient remained hemodynamically stable and free of inotropic support. The report intends to emphasize the potential of the myocardium to recover even after extensive infarction under temporary ventricular support and takes the Impella microaxial hemopump into consideration as a device that is technically easy to implant with no injury to the ventricle and thus associated with good properties for weaning. Surgeons should consider the device as short-term support in borderline indications. [source] Impaired EDHF-Mediated Relaxation in Porcine Pulmonary Micro-Arteries by Cold Storage with University of Wisconsin and Euro-Collins SolutionsJOURNAL OF CARDIAC SURGERY, Issue 6 2002Wei Zou Background: Vascular endothelium plays a key role in regulation of vascular tone. Hyperkalemia has been demonstrated to impair the EDHF-mediated endothelial function in coronary circulation. University of Wisconsin (UW) and Eruo-collins (EC) solutions are used for organ preservation in transplantation surgery. The potassium concentration in UW or EC solutions is as high as 125 mmol/L or 115 mmol/L, respectively. This study was designed to examine whether hyperkalemia or storage with UW and EC solutions affects the relaxation mediated by EDHF in the porcine pulmonary micro-arteries. Methods: Porcine pulmonary micro-artery rings (diameter 200,450 ,m) were studied in myograph (n = 8 in each group). After incubation with hyperkalemia (K+ 125 mmol/L, at 37° C), UW or EC solutions (at 4° C for 4 hours), EDHF-mediated relaxation induced by bradykinin (BK, ,10 to ,6.5 log M) in the presence of inhibitors for cyclooxygenase (Indomethacin, 7 ,M), nitric oxide synthase (NG -nitro- L -arginine, 300 ,M), and oxyhemoglobin (20 ,M) was compared with control (Krebs' solution) in precontraction with U46619 (,7.5 log M). Results: The EDHF-mediated relaxation to BK was 69.6 ± 6.3% compared with 97.1 ± 1.7% (p= 0.003) in control (no inhibitors). After incubation with hyperkalemia, the relaxation significantly decreased (38.6 ± 3.0% vs. 59.1 ± 7.4%, p= 0.03). Storage with UW or EC solutions also significantly decreased the relaxation (49.3 ± 7.3% vs. 65.2 ± 3.5%, p= 0.04 and 51.9 ± 8.4% vs. 60.3 ± 6.1%, p= 0.02, respectively). Conclusions: In porcine pulmonary micro-arteries, exposure to hyperkalemia or storage with UW or EC solutions at 4°C for 4 hours impairs the EDHF-mediated endothelial function. The clinical significance of this effect should be further studied. [source] Neopterin induces pro-atherothrombotic phenotype in human coronary endothelial cellsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2006P. CIRILLO Summary.,Background: Inflammation plays a pivotal role in atherothrombosis. Recent data indicate that serum levels of neopterin, a marker of inflammation and immune modulator secreted by monocytes/macrophages, are elevated in patients with acute coronary syndromes and seem to be a prognostic marker for major cardiovascular events. The aim of the present study was to determine whether neopterin might affect the thrombotic and atherosclerotic characteristics of human coronary artery endothelial cells (HCAECs). Methods and results: In HCAECs, neopterin induced TF-mRNA transcription as demonstrated by real time polymerase chain reaction and expression of functionally active tissue factor (TF) as demonstrated by procoagulant activity assay, and of cellular adhesion molecules (CAMs) as demonstrated by FACS analysis, in a dose-dependent fashion. These neopterin effects were prevented by lovastatin, a HMG-CoA reductase inhibitor. Neopterin-induced TF and CAMs expression was mediated by oxygen free radicals through the activation of the transcription factor, nuclear factor-kappa B (NF- ,B), as demonstrated by electrophoretic mobility shift assay and by suppression of CAMs and TF expression by superoxide dismutase and by NF- ,B inhibitor, pyrrolidine-dithio-carbamate ammonium. Conclusions: These data indicate that neopterin exerts direct effects on HCAECs by promoting CAMs and TF expression and support the hypothesis that neopterin, besides representing a marker of inflammation, might be an effector molecule able to induce a pro-atherothrombotic phenotype in cells of the coronary circulation. [source] Cardiac arrest at induction of anesthesia in a child with undiagnosed right-ventricular dependent coronary circulation: a case reportPEDIATRIC ANESTHESIA, Issue 11 2006TODD A. BROWN MD Summary Pediatric perioperative cardiac arrest occurs in 1.4 per 10 000 anesthetics, with an overall mortality rate of 26%. The etiology of the arrest is identifiable in the majority of these patients. We report the case of a child with a complex congenital heart defect, who sustained a cardiac arrest at induction of anesthesia, secondary to right-ventricular dependent coronary circulation. We discuss the incidence, risks, anesthetic management and outcomes of pediatric cardiac arrest in the perioperative period especially in patients with complex congenital heart disease. [source] A Mathematical Model to Evaluate Control Strategies for Mechanical Circulatory SupportARTIFICIAL ORGANS, Issue 8 2009Lieke G.E. Cox Abstract Continuous flow ventricular assist devices (VADs) for mechanical circulatory support (MCS) are generally smaller and believed to be more reliable than pulsatile VADs. However, regarding continuous flow, there are concerns about the decreased pulsatility and ventricular unloading. Moreover, pulsatile VADs offer a wider range in control strategies. For this reason, we used a computer model to evaluate whether pulsatile operation of a continuous flow VAD would be more beneficial than the standard constant pump speed. The computer model describes the left and right ventricle with one-fiber heart contraction models, and the systemic, pulmonary, and coronary circulation with lumped parameter hemodynamical models, while the heart rate is regulated with a baroreflex model. With this computer model, both normal and heart failure hemodynamics were simulated. A HeartMate II left ventricular assist device model was connected to this model, and both constant speed and pulsatile support were simulated. Pulsatile support did not solve the decreased pulsatility issue, but it did improve perfusion (cardiac index and coronary flow) and unloading (stroke work and heart rate) compared with constant speed. Also, pulsatile support would be beneficial for developing control strategies, as it offers more options to adjust assist device settings to the patient's needs. Because the mathematical model used in this study can simulate different assist device settings, it can play a valuable role in developing mechanical circulatory support control strategies. [source] Invasive assessment of the coronary circulation: intravascular ultrasound and DopplerBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 6 2002David E. Newby First page of article [source] Current status of rotational atherectomyCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 4 2004Erdal Cavusoglu MD Abstract Despite the increasing use of percutaneous transluminal coronary angioplasty and intracoronary stent placement for the treatment of obstructive coronary artery disease, a large subset of coronary lesions cannot be adequately treated with balloon angioplasty and/or intracoronary stenting alone. Such lesions are often heavily calcified or fibrotic and undilatable with the present balloon technology and attempts to treat them with balloon angioplasty or intracoronary stent placement often lead to vessel dissection or incomplete stent deployment with resultant adverse outcomes. Rotational atherectomy remains a useful niche device for the percutaneous treatment of such complex lesions, usually as an adjunct to subsequent balloon angioplasty and/or intracoronary stent placement. In contrast to balloon angioplasty or stent placement that widen the coronary lumen by displacing atherosclerotic plaque, rotational atherectomy removes plaque by ablating the atherosclerotic material, which is dispersed into the distal coronary circulation. Other lesion subtypes amenable to treatment with this modality include ostial and branch-ostial lesions, chronic total occlusions, and in-stent restenosis. This review discusses the technique and principles of rotational atherectomy, the various treatment strategies for its use (including adjunctive pharmacotherapy), the lesion-specific applications for this device, and the complications unique to this modality. Recommendations are also made for its use in the current interventional era. Catheter Cardiovasc Interv 2004;62:485,498. © 2004 Wiley-Liss, Inc. [source] The clinical anatomy of the coronary collateral circulationCLINICAL ANATOMY, Issue 1 2009Marios Loukas Abstract Although the structure and function of the coronary vasculature has been exhaustively studied, it still holds significant elements of mystery for the researcher and clinician. This is particularly true regarding the structure and function of the human collateral coronary circulation. Controversy still exists concerning the pathways of collateral vessels as well as their function. Controversies also exist relative to the methods used to delineate the pathways, these being additionally compounded by the lack of standardization of the studies and measurements. In this review, we summarize our current knowledge of this functionally significant vascular network. Clin. Anat. 22:146,160, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||