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J Thorac Cardiovasc Surg 2003;126:1978-1985
© 2003 The American Association for Thoracic Surgery
Surgery for acquired cardiovascular disease |
a Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, Calif, USA
Read at the Twenty-eighth Annual Meeting of The Western Thoracic Surgical Association, Big Sky, Mont, June 19-22, 2002.
Received for publication June 30, 2002; revisions received June 1, 2003; accepted for publication July 7, 2003.
* Address for reprints: D. Craig Miller, MD, Department of Cardiothoracic Surgery, Falk Cardiovascular Research Center, Stanford University School of Medicine, Stanford, CA 94305-5247, USA
dcm{at}stanford.edu
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Abstract |
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METHODS: Between 1967 and 1999, 123 patients (mean age 56 ± 15 years) underwent composite valve graft replacement (n = 21), separate valve and graft replacement (n = 20), or conservative valve treatment (n = 82 [commissural resuspension in 46]); follow-up averaged 6.5 years (95% complete).
RESULTS: The 30-day, 1-year, and 6-year survival estimates of 85% ± 4%, 79% ± 5%, and 69% ± 5% (±1 standard error of mean), respectively, after conservative valve treatment were similar to 86% ± 8%, 81% ± 9%, and 65% ± 16%, respectively, with composite valve graft replacement and better (but insignificantly so) than 70% ± 10%, 70% ± 10%, and 45% ± 11%, respectively, with separate valve and graft replacement. The 6-year freedom from proximal reoperation was 95% ± 3%, 89% ± 10%, and 100% in conservative valve graft, separate valve and graft, and composite valve graft subgroups, respectively (P = not significant). Cox regression multivariable analysis identified that previous sternotomy (hazard ratio [or eß] 95% confidence interval 1.4-10.9, P = .006), hypertension (0.99-2.9, P = .05), cardiac tamponade (1.1-4.0, P = .03), and stroke (1.7-7.0, P = .001) increased the hazard of death. No factors predicting a higher likelihood of late proximal reoperation were identified.
CONCLUSIONS: In patients with acute type A aortic dissection and aortic regurgitation, there was no significant difference in overall survival or reoperation rates among these surgical approaches. We try to save the valve whenever possible unless the aortic root is pathologically dilated (eg, Marfan syndrome or annuloaortic ectasia) or destroyed by the dissection process, when composite valve graft or valve-sparing aortic root replacement is indicated.
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Methods |
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Operative methods
Although variability in surgical techniques was present among the individual surgeons and the surgical techniques evolved over the years, the surgical approach uniformly was to resect all of the tubular portion of the ascending aorta and, if identified, the primary intimal tear. Earlier, cannulation of the femoral artery was used for cardiopulmonary bypass, but the right axillary artery became the preferred site for arterial cannulation in the late 1990s.2 In recent years, most surgeons have striven to avoid aortic crossclamping whenever possible, resecting the underside of the transverse aortic arch and performing an open distal "hemiarch" anastomosis using profound hypothermic (20°C -25°C bladder temperature) circulatory arrest. In the early 1990s, a brief period of retrograde cold blood cerebral perfusion during completion of the open distal anastomosis was used by some surgeons. When the circulatory arrest period is anticipated to be longer than 30 minutes, selective antegrade cerebral perfusion is now used by most surgeons. During antegrade reperfusion and rewarming, attention is then directed to the proximal aortic root.
The most commonly performed proximal aortic procedure was reconstructing the sinotubular junction circumferentially and tube graft replacement of the ascending aorta. The native aortic valve was preserved whenever feasible. The main technical features of valve resuspension included complete transection of the proximal aorta, obliteration of the proximal false lumen down to the level of the aortic annulus with a custom-tailored piece of Teflon (DuPont, Wilmington, Del) felt inside the false lumen, and resuspension of the aortic valve commissures with circumferential suture reconstruction of the aorta.3 Frequently, this proximal cuff was reinforced by an external layer of Teflon felt. We have never relied solely on placing individual pledgeted mattress sutures at the tops of the commissures for this purpose. In the last 2 years, BioGlue (Cryolife, Inc, North West Kennesaw, Ga) has been used instead of Teflon felt. The graft size was based on the goal of restoring the sinotubular junction diameter to approximate the aortic annular diameter. If attempts at commissural resuspension did not result in valvular competency, then aortic valve replacement using either the SVG or CVG approach was performed.
If the sinuses of Valsalva were excessively dilated (because of annuloaortic ectasia; n = 15, 71% ± 10% of the CVG group [70% confidence interval]), pathologically diseased (eg, the Marfan syndrome [MFS]), or destroyed by the acute dissecting process (n = 3, 15% ± 8% of CVG) with or without irreparable compromise of the coronary arteries (n = 3, 15% ± 8% of CVG), complete aortic root replacement was performed. If it was judged that valvular competency could not be satisfactorily restored or if severe valve pathology was present, valve replacement was performed. CVG replacement (mechanical valve = 20; bioprosthetic valve = 1) and reimplantation of the coronary ostia was always performed as an open procedure using Carrel coronary button anastomoses avoiding "wrap inclusion" (Bentall procedure).
In SVG procedures, the bulk of the sinuses of Valsalva were resected leaving small tongues of aortic root tissue surrounding the coronary ostia. After the aortic valve was excised, a mechanical (n = 1) or bioprosthetic (n = 19) valve was inserted, and a woven synthetic graft was then anastomosed to the proximal and distal aortic cuffs (which were reinforced by 1 or more layers of Teflon felt). The extent of distal aortic resection in patients who underwent operation using hypothermic circulatory arrest and distribution of the location of the primary intimal tear are summarized in Appendix 1.
Follow-up
Current follow-up was obtained by telephone or written communication or both. Follow-up was 95% complete (n = 117), extended to a maximum of 30.7 years, and totaled 761 patient-years (Appendix 1).
Postoperative care
Negative inotropic drug treatment was advised indefinitely, even in normotensive patients.4,5 Serial aortic surveillance with annual computed tomography or magnetic resonance imaging scans was also recommended, but compliance with this recommendation could not be ensured.
Statistical methods
Outcomes
Valve-related complications have been detailed in a previous report.6 Time-related events studied included death at any time after operation and reoperation for proximal aortic complications. Freedom from these time-related events was estimated by the nonparametric actuarial Kaplan-Meier method. For freedom from reoperation, a nonfatal event, actual (or observed cumulative frequency) probabilities were also computed. Analyses stratified according to treatment modality were compared using the log-rank test. Early mortality was defined as death within 30 days of treatment or during the same hospitalization, regardless of time. The variability of continuous data is expressed as mean ± 1 SD, the variability of important fractions or ratios is expressed as ±70% confidence levels (CL), and the variability of actuarial or actual estimates is expressed as ±1 SEM, approximately equivalent to ±70% CL. Events arising from 1 or more valve-related complications were infrequent and thus were expressed as linearized rates (events per patient-year).
Identification of predictors of outcome
The influence of 25 preoperative characteristics or dissection-related complications (independent variables) on outcome (dependent variables) was analyzed by using SPSS for Windows (Release 10.0.0; SPSS Inc, Chicago, Ill). These independent variables included age, gender, duration of symptoms, year of operation, surgeon experience, shock, acute aortic insufficiency, paraplegia, visceral ischemia, renal dysfunction, peripheral pulse deficit, arch involvement, stroke, coronary artery disease, congestive heart failure, pulmonary disease, liver disease, diabetes mellitus, prior stroke, MFS, hypertension, previous dissection, previous sternotomy, tamponade, and rupture (Appendix 1). The predictors of time-related outcome were identified, and their hazard ratios (HR or eß) with 95% CL were determined from Cox proportional hazards analysis.
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Results |
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Late death
Death from aortic-related complications was defined as that caused by progression of dissection and/or rupture and those that were sudden and unexplained. The causes of late death are listed in Table 1. None of the patients in the CVG group died from an aortic-related complication; 2% of the patients in the SVG group and 15% of the patients in the CONS group could have possibly died as the result of an aortic complication. This raw fractional difference in cause of late deaths did not attain statistical significance. Stroke accounted for 5% of late deaths in the CONS group and 2% in the SVG group. Anticoagulant-related hemorrhage did not cause any late deaths in the CVG group but was responsible for 2% of late deaths in the SVG group. Comorbidities, such as congestive heart failure, accounted for a high proportion of late deaths in the CONS group relative to the CVG and SVG groups, but more patients with residual aortic valve regurgitation were not detected at follow-up in the CONS group. Sepsis led to 1 late death in the CVG group in the absence of evidence of endocarditis at autopsy.
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Discussion |
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Contrary to our experience, the use of Teflon felt for reconstruction of the aortic root has not met with widespread uniform success.9,13,16 Niederhauser and colleagues9 reported that at 2 years, patients who underwent gelatin-resorcin-formaldehyde (GRF) (or "French" glue) reconstruction of the aortic root had an increased freedom from reoperation on the aortic root (92% vs 70%, P = .02) and event-free survival (77% vs 41%, P = .02) compared with simple suture resuspension. Although we recognize the benefits of a tissue adhesive in creating a sturdy substrate for suturing and have moved to BioGlue as a substitute for Teflon felt, we remain dubious about GRF in light of recent reports of GRF-related tissue necrosis of the aortic root.17
Overall, supra-commissural aortic valve resuspension has exhibited relatively excellent long-term durability in this and other series.6-8,10,11,16,18 There is, however, 1 confounding factor: The reported long-term durability of the repair may artifactually be better when all patients are considered instead of just those with AR.8,11,18,19 Pessotto and coworkers7 and Mazzucotelli and coworkers11 reported that the presence of moderate-to-severe aortic insufficiency in patients portends an increased rate of reoperation (>37%-39% of patients) compared with patients with no or mild AR. Kirsch and colleagues from the Hôpital Henri Mondor20 reported that severe AR increased the HR of reoperation on the proximal aorta by 3.6-fold (1.44-9.07; 95% confidence interval) and recommended more frequent consideration of CVG (or valve-sparing aortic root replacement) at the time of the initial operation in patients with severe AR. We concur given that moderate-to-severe AR may be a surrogate for more pronounced aortic root disease.
Freedom from aortic root reoperation was independent of both surgical treatment method and patient-related risk factors. The MFS did not emerge as a risk factor for reoperation, as intuition would dictate, perhaps because most patients with MFS received a CVG procedure. The fact that this analysis was unable to identify factors predicting an increased likelihood of reoperation reflects appropriate patient selection for the various procedures, namely, customizing the operative procedure to the patient and his or her disease.
The actuarial estimate of freedom from reoperation in the SVG group was "artificially" lowered by the strong competing hazard of death; when expressed as an actual estimate, freedom from reoperation was comparable to that in the CONS and CVG groups (Figure 3). Nonetheless, we basically abandoned the SVG procedure in 1989 (Figure 1). Indeed, Moon and colleagues19 reported a very high operative mortality rate of 50% ± 16% for patients undergoing SVG; however, similar to our findings, they found no difference in late aortic reoperation or survival depending on which aortic root operative technique was performed initially. Patient survival, including early postoperative mortality, also was not influenced by treatment method; it seems that patient substrate was the main determinant of survival, a finding corroborated by Niederhauser and colleagues.9 The predictors of short- and long-term survival were patient-related and dissection-related factors, which for the most part cannot readily be modified. There is some debate concerning whether long-term survival and operative mortality risk after either an aggressive or a more conservative aortic root procedure are comparable in centers with special thoracic aortic expertise.8,9,11,18,19 Ergin and coworkers21 from Mount Sinai reported that patients undergoing total root replacement represented a higher operative risk subset as the result of having substantial AR and coronary dissection, but paradoxically had substantially better event-free survival estimates at 5 years (88% ± 12% vs 67% ± 9%) and 9 years (88% ± 22% vs 63% ± 19%); these authors recommended that root replacement should be considered more frequently. On the other hand, data reported by Sabik and colleagues18 from the Cleveland Clinic showed that CVG carried a significant adverse impact on overall survival (P = .0009), primarily in the early hazard phase. von Segesser and coworkers8 have argued that simple preservation of the valve offers a sound long-term prognosis without exposing the patient to undue risk. The general consensus today6-8,13-15,18-20,22 indicates that a more aggressive surgical approach (eg, CVG) should be considered only in special circumstances.
The David "reimplantation"23 or Yacoub "remodeling"24 methods of valve-sparing aortic root replacement combined the benefits of aortic root replacement as well as preservation of the aortic valve; thus, this may be an even better alternative for repair of the dissected aortic root in highly selected patients with an acute type A aortic dissection and AR. The early results reported by Graeter and colleagues from Homburg,25 Leyh and colleagues26 from Lubeck, and the cardiovascular surgical group from Hannover27 have been encouraging. The outcome after CVG and CONS procedures reported in this article will serve as clinical benchmarks in the future to assess the putative long-term benefits of this "ultraradical" valve-sparing surgical approach as applied to these very challenging patients.
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Limitations |
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Acute AR was present in only 123 of 307 patients (40%), which is less than the 59% and 100% reported by Ehrlich and coworkers28 and Niederhauser and coworkers, respectively.9 This discrepancy is probably attributable to different methods for classifying the severity of acute AR rather than the acuity of disease. A possible selection bias may have been introduced by excluding 28 patients in the CVG and SVG groups who did not have AR preoperatively; analysis of all 307 patients with or without AR did not change the major conclusions, but SVG was associated with a higher probability of proximal aortic reoperation.
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Conclusion |
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Discussion |
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In closing, we believe that this is first and foremost a lifesaving procedure. The operation of choice has to be the one that each individual surgeon has confidence in to minimize the early operative mortality. I have 2 questions. You would assume that the composite graft group would have more extensive pathology, more aortic insufficiency, more destruction of the root tissue, greater incidence of rupture, tamponade, and so forth. However, this group compared favorably with the repair group, and indeed none died of aortic-related complications, and there were no strokes or anticoagulant deaths. Congestive heart failure, on the other hand, accounted for a high percentage of late deaths in the repair group compared with the conduit and separate valve graft group. Do you have any insight as to why this may be? I truly appreciate and thank you all for having me address this article.
Dr Lai. Thank you very much for your comments, Dr Floten. Congestive heart failure may suggest that there might be underlying valvular insufficiency that was not apparent at clinical follow-up. The follow-up at Stanford University is not absolutely perfect given the geographic disparity from which the patients were referred, and it is possible that some of these patients may have had incipient and underlying aortic valve insufficiency that was not clinically apparent and that led to congestive heart failure and subsequent late death.
Dr Walter Wolfe (Durham, NC). I am struck by the low incidence of AR in 300 cases. In my experience if we could go back to the DeBakey classification, in which types 1, 2, and 3 were used, type 2 dissection was the least common, probably because they did not have AR and they did not decompress downstream; the patient probably died, and the death was written off as a heart attack somewhere else. In my experience with type 1, type A, almost everybody had AR, and the procedure of choice has been resuspension of the valve with supracoronary graft. Did you have a lot of what we would call type 2 dissections in which the dissection stops at the arch and there is usually no AR?
Dr Lai. Most patients in this series had DeBakey type 1 dissection, and the extent of dissection went beyond the arch in more than 80% of patients. Only a small number of patients had DeBakey type 2 aortic dissections in the Stanford series. Aortic valve insufficiency was present in approximately 30% of our patients, and this is a finding that has been echoed by other series, larger series, that are published in the literature. Perhaps we are not looking hard enough to detect aortic valve insufficiency, but even in the last 4 to 5 years' data, in which most patients routinely underwent echocardiography, the prevalence of aortic valve insufficiency was still in the vicinity of 30%.
Dr Donald Doty (Salt Lake City, Utah). Would you comment on 2 things? One, the use of biologic glue in the repair of the aortic root, and second, what do you do about dissection that progresses through the aortic arch? Is there any place for treatment of the arch during the primary operation?
Dr Lai. Thank you for your questions, Dr Doty. We switched to BioGlue when we found it created a sturdy substrate, and I guess your question about BioGlue raises the safety of other types of glue like the GRF glue. There have been a number of reports in the literature showing that there is a higher incidence of tissue necrosis in association with the GRF glues, and Dr Bachet thinks that is a problem of improper application of this glue in which too much formaldehyde may have been used. Our experience with BioGlue has been sort of limited in the sense that there is a short experience in the last 2 years. We have had no problems with tissue-related necrosis to date, and it is easy to use with well-controlled application. There is very little risk of spill-over into the lumen and very little risk of embolization from that point of view.
The Stanford University faculty have adopted a rather aggressive approach to arch dissection, and even if the primary intimal tear is located in the ascending aorta, they will routinely use a no-clamp technique under hypothermic circulatory arrest and resect the underside of the aortic arch even if the arch is dissected and not aneurysmal. When there are more extensive arch dissections and arch tear, they will go on to a more aggressive arch replacement, which may even include an elephant trunk procedure. There has been a move in the aortic dissection centers around the world, particularly in Japan and Germany, to be more aggressive in treating the young patient with MFS and arch dissection; the ascending aorta is completely replaced in the form of a valve-sparing aortic root replacement combined with a total arch replacement, either using a single island or branched arch prosthetic conduit combined with placement of conduit in the descending thoracic aorta and followed by interval placement of stent grafting of the descending thoracic aorta. So there are moves afoot to be more aggressive in a young patient, but I should caution that treatment should be performed in highly select centers with good radiologic backup for subsequent interval stenting and in patients who are at risk for further disease (such as a young patient with MFS). This approach certainly does not apply to the elderly hypertensive patient with renal dysfunction and various other comorbidities in which we should limit our losses.
Dr Kent Jones (Salt Lake City, Utah). You said in your conclusion slide that on the basis of your study the surgeon's preference would determine which of these 3 techniques would be used. If a patient with type A dissection comes into Stanford today, what would be the overall consensus as to how that patient would be treated surgically, the technique that would be used?
Dr Lai. There is a unit consensus, although it may not be applied completely by all surgeons in the department, to adopt the approach of hypothermic circulatory arrest, with no crossclamping, to use an aggressive approach in a young patient (as we have alluded to earlier on) and a more conservative approach in the elderly patient, to use BioGlue to reconstitute the dissected aortic wall, and to resect a primary intimal tear whenever possible.
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APPENDIX 1 |
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* P < .05.
** P < .01 by either 
2 test or analysis of variance.
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Footnotes |
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