ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The treatment of coronary artery disease in general and the results achieved with coronary artery bypass grafting in particular continue to be intensely studied. Long-term follow-up from ongoing studies and the studies of the role of percutaneous interventions continue to provide new information. The refinement of our understanding of long-term outcome in various subsets of patients, preoperative risk factors, technical modifications, and postoperative interventions will influence the selection of appropriate treatment for patients with coronary artery disease.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The wider application of arterial conduits represents a current trend in myocardial revascularization. More complex and demanding surgical techniques are being developed as alternatives to traditional grafting procedures, in order to permit total arterial revascularization in patients with diffuse coronary artery disease. The rationale behind this strategy is the expected higher long-term patency rate of arterial conduits as compared with vein grafts. Avoidance of proximal anastomoses is another argument in favor of coronary revascularization with arterial grafts, particularly in patients with atherosclerotic changes in the ascending aorta. Although the reported operative results are good, total arterial revascularization in multivessel disease is a complex procedure, and serious perioperative complications are possible. In planning the revascularization strategy, therefore, the surgeon should take into account age, clinical condition, coexisting medical problems, coronary anatomy, and left ventricular function. The method of myocardial revascularization is an important aspect of the surgical procedure and plays a major role in the outcome of the operation in the presence of severe left ventricular dysfunction or when the operation requires prolonged ischemic times. To avoid the inevitable damaging effects of cardiopulmonary bypass and aortic cross-clamping, myocardial revascularization is carried out without extracorporeal circulation. This technique should be part of the armamentarium of the cardiac surgeon and should occasionally be considered in patients who have serious coexisting medical problems or severe left ventricular dysfunction.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Saphenous vein graft failure is one of the primary reasons for coronary artery bypass reoperation. The economic impact alone in this country is staggering in an era of intensive cost cutting. The fact that some vein grafts remain free of disease for years while the sibling vein develops extensive atherosclerosis remains an enigma. Saphenous vein valves have recently attracted interest. Repeated angiograms show that vein graft disease invariably is accentuated around valves. Studies show that the segment of saphenous vein distal to the valves have more accelerated and intense atherosclerosis. Early results of saphenous vein bypass grafting may be predicted with some degree of certainty by saphenous vein graft biopsy. Attention is now being turned to the hypercoagulable state as a cause of graft failure, as this has not been previously addressed. Research into pharmacologic agents for maintaining open grafts has had disappointing results and aspirin alone is still the single drug of choice to promote patency. Preparation of the graft continues to be important because there is direct evidence that surgical injury during preparation leads to neointimal thickening and vascular smooth muscle proliferation. Although there are some exciting new modalities for preventing graft disease, the difficulty in transposing animal data to humans and the uncertainty of the biologic similarities of in vitro and in vivo endothelial cell biochemistry makes any immediate solution unlikely. Therefore an even greater increase in the use of arterial grafts in the near future seems likely, even with their associated problems.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Whatever the method, the biologic price of restitution of arterial flow through or around an obstructed artery is injury to the arterial wall. The artery mounts a healing response that in 30% to 60% of procedures exceeds the need. The result is formation of a lumen-narrowing lesion composed of smooth muscle cells and extracellular matrix with varying amounts of atherosclerotic components. The primary player appears to be the smooth muscle cell. For four decades the standard model for studying these events has been catheter denudation of arterial endothelium in small animals. Molecular biology has provided an enormous amount of new information including growth factors, adhesion molecules, receptor binding sites, and molecules that up- or down-regulate or maintain a steady state of expression of numberless genes in the arterial wall. Predictably, means of inhibiting these molecular events have been found. That their clinical trials have been universally disappointing should not be surprising given that the animal in which the discoveries were made—the rat—is not normally susceptible to atherosclerosis and the histology of the rat artery only approximates that of the human. Nevertheless, reason for optimism exists because of our increasing understanding of the injury response. Recent developments include the use of blocking antisense oligonucleotides, blocking antibodies, gene transfer trials, and early investigations into the role of the immune system.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

In the past, most strategies for intraoperative myocardial protection were developed in models using nondiseased adult hearts from various animal species. In the clinical setting, however, myocardial status in cardiac patients may be quite different and there is a need to adapt our current protective strategies to the actual pathophysiological status of the heart. In the immature heart as well as in the senescent heart, current protective techniques have been shown to be deficient and further research is required. New insights have been gained into the pathophysiological processes underlying chronic ischemic left ventricular dysfunction in the “hibernating” myocardium. It has been shown that viability in these hearts is associated with subcellular alterations related to dedifferentiation of the myocytes. This finding explains the delayed recovery in function of these hearts after revascularization and the need for intraoperative protective strategies focusing on the prevention of stunning in the nonhibernating segments. Tepid continuous retrograde blood cardioplegia is suggested as the optimal technique. Unraveling the mechanisms of preconditioning in the heart and understanding endogenous myocardial protection may provide clues for novel cardioprotective techniques. Adenosine itself may be used as an adjunct to cardioplegia, and treatment with adenosine regulating agents or nucleoside transport inhibitors shows promising results. Like adenosine, other hyperpolarizing agents (potassium-channel openers) are suggested for arrest of the heart instead of the depolarizing agents commonly used in cardioplegia. Finally, the role of Na+-H+exchange in the development of ischemic and postischemic injury has become more clear. By the use of a new selective Na+-H+exchange inhibitor, postischemic contracture can be dramatically reduced and contractility improved. This opens prospective approaches in emergency coronary bypass surgery for evolving myocardial infarction.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The use of blood and blood products in cardiac surgery has undergone marked changes over the past three decades. This revolution occurred primarily through the study and understanding of hemodilution. This review marks the changes in the practice of blood transfusion in cardiac surgery. We review the methods of blood conservation through preoperative screening and preparation, intraoperative drug therapy and modification of surgical techniques, and postoperative use of shed mediastinal blood. We also examine the physiologic effects and limitations of hemodilution in adult and pediatric cardiac surgery. Finally, we review the recent trends in the use of blood component therapy and the future of blood substitutes.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Any therapy must have a benefit and a risk. The benefit of aprotinin therapy in reducing bleeding is well known. Data presented over the past 12 months have confirmed this efficacy and the superiority and consistency of aprotinin therapy in direct comparison with other pharmacologic (desmopressin, tranexamic acid) and physical (administration of fresh platelet concentrate) interventions. The debate has now changed to focus on issues of the safety of this agent. In particular, concerns have been expressed as to the effect of this agent on renal function, thrombotic potential (and thus graft patency), and adverse reactions on a second exposure. Most recent reports show plasma creatinine concentrations are higher in treated than in nontreated patients on the 3rd or 4th postoperative day. The concentrations reached were not outside the clinical range, and there were no clinical sequelae of this biochemical abnormality. Focused studies have shown no effect of the use of aprotinin therapy on early graft patency or the incidence of thromboembolic complications. The reporting of hypersensitivity reactions following aprotinin administration suggests that the incidence is not different to other agents used in open heart surgery. Three reports of fatal or near-fatal cardiovascular collapse associated with the use of aprotinin followed the apparently inappropriate administration of the agent.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Cardiopulmonary bypass triggers a generalized inflammatory response that is largely mediated by activation of polymorphonuclear neutrophils, their adhesion to endothelial cells, and the subsequent release of cytotoxic products. It has been known for several years that the inflammatory response to extracorporeal circulation underlies the occasional development of postoperative organ—in particular, lung—dysfunction. It is now increasingly recognized that this response can adversely affect myocardial function as well. These harmful effects are exerted by a wide spectrum of compounds, regardless of whether they act as triggers (complement-derived anaphylatoxins), mediators (cytokines, adhesion molecules), or effectors (proteolytic enzymes, oxygen free radicals, leukotrienes) of the inflammatory cascade. These considerations suggest that future strategies of myocardial protection must not be limited to interventions targeted at the heart itself but should also encompass those designed to blunt the inflammatory response to cardiopulmonary bypass.

ISSN:0268-4705    

出版商:OVID    

年代:1995

数据来源: OVID