| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 1996;62:1311-1312
© 1996 The Society of Thoracic Surgeons
DR W. R. ERIC JAMIESON (Vancouver, British Columbia, Canada): It is a distinct privilege for me to discuss this very outstanding paper, and I congratulate Dr Fann on his excellent presentation and the manuscript as well. I did have the opportunity to review the manuscript well in advance of the meeting.
This is a continuation of the contributions from Stanford on the evaluation of porcine bioprostheses and will serve as a landmark paper regarding the evaluation of new prostheses. They have concluded that porcine bioprostheses are indicated for aortic valve replacement and for use in the elderly. We have also, at the University of British Columbia, confirmed these findings and agree totally with their experience. They have indicated that age is an independent predictor of all valve-related complications and composites of these complications, except for valve-related mortality, which is worthy of consideration. They have also identified that increased surveillance may be responsible for identifying the need for early reintervention for the management of failure and is a factor, an independent predictor, of the performance.
I might digress slightly. Yesterday we heard a paper that evaluated and recommended mechanical prostheses for aortic valve replacement. Our findings at the University of British Columbia are at variance with these findings. We have identified that the freedom from thromboembolism and anticoagulant hemorrhage is fourfold greater in elderly patients who undergo valve replacement using a porcine bioprostheses. Consequently, we agree with the Stanford recommendation.
They have evaluated 18 variables in their assessment, and the only questions I have for Dr Fann are those related to these independent predictors, and there are three such questions.
Could you discuss your reasons for why hepatic insufficiency is an independent predictor of structural failure for aortic valve replacement, a finding I know you have identified previously, and why is it not such a predictor for mitral valve replacement?
You have identified a higher NYHA functional classification, congestive heart failure, and, interestingly, longer cardiopulmonary bypass and longer cross-clamp time as predictors of valve-related mortality. I assume that this is also related to the inclusion of early mortality in your valve-related mortality findings, but is it related to the long-term effect of myocardial preservation in patients at the time of reoperation and the fact that this is a long-term, 20-year experience? Is it related possibly to techniques of preservation? For a long time, Stanford certainly was a proponent of topical cold as a method of preservation.
With regard to the risk factors for valve-related mortality and morbidity, these have included congestive heart failure, hypertension, and the absence of angina. It would have been interesting to me, at least, for you to assess coronary artery bypass grafting for coronary artery disease as an independent predictor rather than just the presence or absence of angina, for this will also be an indication of ventricular dysfunction in conjunction with the presence or absence of angina.
It is certainly a privilege to discuss this landmark paper, which I feel will serve as a benchmark for the comparison of newer prostheses, and I thank The Society for the privilege of discussing this paper.
DR FANN: Doctor Jamieson, thank you for your comments. Your group's contribution in furthering our knowledge of bioprosthetic valve performance has been tremendous over the years; in fact, many points that you have stressed in your previous analyses were also assessed in this study.
Based on multivariate analysis, hepatic insufficiency was a predictor of structural valve deterioration in the aortic subgroup; this finding was also evident in a recent comparative analysis of the Hancock MO prosthesis with other standard aortic valve bioprostheses from our institution. Because of the relatively small number of actual events, this may be a statistical aberration; at present, we do not have an explanation for this finding.
With regard to valve-related mortality, we found higher NYHA functional class, longer cardiopulmonary bypass and cross-clamp time, congestive heart failure, and renal insufficiency to be significant predictors. As defined by The American Association for Thoracic Surgery and The Society of Thoracic Surgeons Joint Committee, valve-related mortality includes all sudden, unexplained early and late deaths. It is likely that higher NYHA functional class, congestive heart failure, and renal insufficiency are related to the incidence of late mortality; whether these factors are directly associated with valve-related mortality is conjectural. This finding points to the fact that valve-related mortality is probably an overestimate of the true mortality associated with a given valve prosthesis.
We have modified our method of cardioplegia administration over the years, varying from antegrade cold crystalloid cardioplegia with topical cold to a combination of antegrade and retrograde warm/cold blood cardioplegia. We have not analyzed the effects of the method of myocardial preservation on the estimate of valve-related mortality.
Predictors of valve-related morbidity and mortality include congestive heart failure, hypertension, and the absence of angina. It is unclear why absence of angina is a risk factor in this analysis; I agree that a more comprehensive analysis would include other variables, such as the presence of coronary artery disease and whether the patient underwent CABG (as reported by the group at Emory).
DR ROBERT L. REPLOGLE (Harvey, IL): Doctor Fann, although you did not find a difference in deterioration by manufacturer, was there any difference in deterioration based on the fixation techniques or preservation techniques used?
DR FANN: This analysis is a long-term evaluation of first-generation bioprostheses; therefore, the fixation techniques are relatively similar and have remained basically unchanged, with few modifications, over the years. At present, we do not have access to newer bioprosthetic valves prepared using different methods of preservation or fixation for analysis or experimentation.
| ||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
