ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

The introduction of the Toronto stentless porcine valve (SPV) (St. Jude, Minneapolis, MN), recently approved by the Food and Drug Administration following a 6-year multi-institutional clinical trial from 1991 to 1997, reflects an evolutionary pursuit of an ideal valve substitute, namely, low thrombogenicity, freedom from anticoagulation, durability, easy availability, resistance to infection, and easy implantability. Currently, four different types of valve replacement have been time tested: mechanical valves, cryopreserved aortic homograft, stented heterograft, and pulmonary autograft (Ross procedure), and none of the available valve substitutes meet all the criteria of an ideal valve. The mechanical valve’s favorable properties of durability and easy implantability are susceptible to thrombus formation, which requires lifelong anticoagulation. Although the aortic homografts are durable, with low incidence of infection and thrombogenicity, their widespread application has been limited by the lack of availability. The pulmonary autograft, with its native aortic valve properties, has been shunned by some surgeons because it requires a demanding technical expertise in implantation and needs an allograft in the pulmonary position. Stented xenografts are characterized by “off-the-shelf” availability, freedom from anticoagulation, easy implantability, and low incidence of infection. Its major drawback has been its limited durability. Another limitation is its residual transvalvular gradient. A modified version, a stentless xenograft, has been introduced to improve hemodynamic profiles in the hope of subsequent superior structural durability and patient survival. Two valves have been approved by the Food and Drug Administration, the Toronto SPV and the Freestyle valve (Medtronic, Minneapolis, MN). At The Methodist Hospital and the Baylor College of Medicine, the Toronto SPV stentless valve has been our stentless xenograft valve of choice. We therefore review the historical evolution, design advantages, surgical techniques, and clinical outcomes of this valve.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Bacterial endocarditis is an important cause of cardiac valvular problems. The diagnosis of bacterial endocarditis can be difficult, and, often, an aggressive clinical evaluation including serial blood cultures is necessary. The pathophysiology of endocarditis is changing with the rise of intravenous drug use; staphylococci are an increasingly common cause. Endocarditis often warrants surgical intervention. Operations for bacterial endocarditis range from valve repair to valve replacement to homograft replacement. The operations are technically challenging, but new methods of myocardial protection have markedly improved the surgical outcomes. Valve excision is an option for intravenous drug users with tricuspid valve endocarditis. Surgical management of endocarditis is a technically challenging but rewarding procedure that should be offered to appropriate patients.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Pulmonary homografts are used more frequently in cardiac surgery. They are used primarily for reconstruction of the right ventricular outflow tract, both in children with complex congenital disease and in adults undergoing the Ross procedure for aortic valve replacement. They have been used for left ventricular outflow tract reconstruction, but they are less durable in this high-pressure position. They have excellent hemodynamic characteristics, require no anticoagulation, and are free from problems of thromboembolism. However, there is concern that over time pulmonary homografts may develop stenosis secondary to low-grade immune reactions. Even as they become more popular, a shortage of available grafts may limit their use.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Minimally invasive as it applies to aortic valve surgery refers to the exposure required to perform the aortic procedure, because total cardiopulmonary bypass is still required. Initial experience used the anterior thoracotomy, but recent series report the ministernotomy or “J” incision as the preferred technique for exposure. Though pain, blood loss, and length of stay may not be significantly different when compared with the conventional technique, lower costs and earlier recovery may be achieved. Minimally invasive aortic valve surgery is a technique that is still evolving.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Heart transplantation is considered the treatment of choice for patients with advanced heart failure. Given the excellent results with transplantation, there has been growing pressure to liberalize eligibility criteria, especially with regard to age. Registry data and early reports have indicated that there may be increased posttransplantation mortality in older patients. A number of single-center reports have shown that survival of older patients may be similar to that of younger patients. The limited supply of donor hearts makes it imperative that careful consideration be given to transplantation results in older recipients and to the overall impact that expanding eligibility criteria for transplantation will have. The limited supply of donor hearts has also led to increased interest in the use of hearts from older donors. This review presents a current perspective on outcomes after heart transplantation in older recipients, use of older donor hearts, and the matching of donor and recipient risk.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Current practice in the monitoring of cardiac transplants revolves around the use of the endomyocardial biopsy. While this is effective for the identification of an ongoing immune response in the graft, for years investigators have explored less invasive approaches in the hope of achieving the same goal by examining the patient’s immune response. For a number of years, lymphocytes, their subsets, and their level of activation in the periphery were investigated. To a large degree, it was a lack of specificity in these approaches that led to their falling out of favor. Examination of donor-specific reactivity by means of lymphocyte proliferation assays has also been used; however, these approaches have been impeded by the time and effort required to accomplish them. During the last few years, flow cytometric cross-matching during the posttransplant period has been used at our institution. While this cross-matching focuses on the humoral immune responses, we have found it to be of value in identifying patients at risk of rejection and in allowing the assessment of treatment modalities used to treat ongoing rejection. While the perfect approach remains to be found, the potential advantages of immunologic monitoring would seem to justify continued study.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Despite the significant advances in transplantation immunology and immunosuppressive therapies over the past 30 years, current immunosuppressive regimens are still inadequate in the majority of cardiac transplant recipients. Although short-and long-term survival rates have improved significantly, only 50% will survive 10 years and very few will survive 20 years. Complications of overimmunosuppression and underimmunosuppression account for the majority of these deaths. Only true “immunologic” tolerance can provide the outcome we pursue, namely, prolonged allograft function and otherwise normal immune function without chronic immunosuppressive therapy and its risks. Until a successful tolerance-inducing protocol is developed, we must use the current and upcoming immunosuppressive agents and techniques.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Sinus node dysfunction occurs commonly after orthotopic heart transplantation and may be caused by surgical trauma, ischemia to the sinus node, rejection, drug therapy, and increasing donor age. In the past, using the standard biatrial technique described originally by Lower and Shumway, many series have reported permanent pacing in more than 10% of patients. Unlike sinus node dysfunction in nontransplanted patients, which typically worsens with time, sinus node dysfunction in the transplanted heart usually improves over a period of weeks to months. Delaying the implantation of a permanent pacemaker may render it unnecessary. The development of the bicaval technique for implantation of the donor heart appears to have decreased even further or even eliminated the need for early permanent pacing. Because sinus node dysfunction in the transplanted heart does not predict subsequent development of atrioventricular (AV) node dysfunction, rate-responsive atrial pacing should be used in the majority of cases. Even after appropriate pacing for sinus node dysfunction, the sinus node may recover and permanent pacing may be discontinued. AV conduction abnormalities are far less common and generally occur late after transplantation. Dual-chamber pacing is required and permanent pacing should be continued indefinitely.

ISSN:0268-4705    

出版商:OVID    

年代:2000

数据来源: OVID