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Ann Thorac Surg 1995;59:1397-1403
© 1995 The Society of Thoracic Surgeons

Should the Freehand Allograft Be Abandoned as a Reliable Alternative for Aortic Valve Replacement?

Divisions of Cardiothoracic Surgery, Cardiology, and Anesthesiology, Emory University School of Medicine, Atlanta, Georgia

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Cryopreserved aortic allografts were used for aortic valve replacement in 80 patients between 1986 and 1994 (infracoronary in 46 and complete root replacement in 34). Hospital mortality was 6.3% (5/80) with all deaths occurring in the infracoronary group. Three of five deaths were in patients with endocarditis and valve ring abscess. Left ventricular-aortic mean pressure gradients across the allograft valves were significantly lower for root replacement patients (mean, 9.0 ± 6.9 mm Hg versus 18.1 ± 8.7 mm Hg for infracoronary patients) (p = 0.0001). No patient having root allograft replacement had early echocardiographic aortic insufficiency greater than grade 1 versus 28% of those having infracoronary implantations. Late aortic insufficiency of grade 2 or greater was seen in 46% of patients having infracoronary implantation versus 17% of patients having root implantation. Nine patients had explantation of an aortic allograft (eight infracoronary and one root). Reasons for explantation were as follows: endocarditis (three infracoronary, one root), technical (three infracoronary), undiagnosed idiopathic hypertrophic subaortic stenosis (1 patient), and prolapsing infracoronary leaflet (1 patient). Actuarial freedom from grade 3 and 4 aortic insufficiency or explantation was 77% at 7 years for infracoronary implantations. We conclude that the infracoronary aortic allograft has an unacceptable frequency of late insufficiency and its use in this position should be abandoned. The substantial incidence of late endocarditis in the infracoronary (freehand) aortic allograft was surprising. In aortic root allografts the progression to grade 2 valvular insufficiency (moderate) in 17% of patients by 22 months must be viewed with concern.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
See also page 1403.

See also page 1404.

Since the introduction of the aortic valve allograft as an alternate choice for valve replacement by Ross in 1962 and Barratt-Boyes in 1964, great interest and numerous modifications in procurement, preservation, and technical implantation have occurred [1–5]. Questions persist as to the physiologic consequences of allograft immunogenicity, whether stromal components of the valve are viable after prolonged implantation, the effect of the cryopreservation process on leaflet retraction with subsequent valvular incompetence, and whether long-lasting durability and valvular competence is a true characteristic of this valve [1].

There is abundant evidence at present that precision of allograft insertion is most important in predicting early and long-term success [1]. The major factors affecting time-related curves of valve function are technical ones encountered at the time of valve implantation [1]. It is probable that even a slight technical error in freehand (infracoronary) insertion of a homograft valve, so that it is not geometrically perfect, increases the stress on the leaflets (living or not) so that the failure mode is more rapid [1].

Use of the infracoronary technique of allograft implantation has been associated with a difficult learning curve, sometimes giving inconsistent and unpredictable results [2, 5]. To eliminate errors of geometric misalignment, use of the allograft root with coronary artery reimplantation has been suggested as a means of utilizing the protective benefits of the full aortic cylinder to avoid leaflet incompetence [6–8].

This study was designed to evaluate the effectiveness of the allograft valve as a satisfactory choice for aortic valve replacement and to determine possible differences in valve function between the allograft implanted by the infracoronary and complete root replacement techniques. In this analysis, 80 patients having allograft aortic valve implantation were evaluated by two-dimensional, color-guided Doppler echocardiography to assess hemodynamic function of the valves implanted by the two techniques.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Patients
Between January 1986 and August 1994, 80 adult patients had allograft valve replacement using either the infracoronary (n = 46) or complete root replacement (n = 34) technique. Seventy-two percent were men, with a mean age of 46.3 ± 14.6 years for the entire group. Indications for operation were primary valve disease (aortic stenosis, aortic insufficiency) in 60 patients (75%) and associated aortic root pathology (annuloaortic ectasia, aneurysm, dissection) in 20 patients (25%). Native valve endocarditis was the reason for operation in 12 of the 80 patients (15%).

Valves were procured from the Virginia Tissue Bank and Cryolife (Marietta, GA) from living organ donors less than 50 years of age according to methods promulgated by O'Brien and associates [9]. One method of preservation (antibiotics for 24 hours at 4°C, then cryopreservation at -176°C) was used during the entire period of the study. No attempt was made to match donor and recipient blood types.

Surgical Technique
The infracoronary implantation technique was used exclusively in 46 patients from 1986 to 1991. Selection of a homograft 2 to 3 mm smaller than the measured annular diameter was accomplished in all patients. After an initial bad experience with one patient, whenever aortic annular size exceeded 26 mm in diameter, a valve other than a homograft was selected. The proximal suture line was performed with 3-0 Tevdek (Deknatel, Fall River, MS) and the distal suture line with 4-0 Prolene (Ethicon, Inc, Summerville, NJ), with elevation of the commissural posts approximately 1 cm above the sinotubular ridge [5]. In most patients the noncoronary sinus of the allograft was retained according to the recommendation by Ross [10]. Infracoronary implantation in general was performed by the methods of Ross [10], Barratt-Boyes [11], and O'Brien and associates [4].

When the allograft was used as a complete root replacement, principles espoused by Ross again were employed with some modifications. Specifically, the following procedures and concepts were stressed: homograft and annular size were more nearly the same diameter (1-to 2-mm difference), minimal trimming of septal muscle, inversion of the allograft for leaflet protection, use of proximal sutures of 3-0 Prolene with interposition of Teflon felt as part of the suture line to prevent tissue tearing and allow secure seating of allograft to annulus (Fig 1), length of allograft aorta kept at minimum, retention of large buttons of recipient coronary ostia, use of felt on allograft aorta wherever sutures were placed to avoid tearing of cryopreserved tissue during systolic aortic expansion, and development of adequate length of recipient coronary ostia to avoid tension and kinking once coronary arteries were implanted into the allograft.

View larger version (79K): [in this window] [in a new window]   Fig 1. . Method of allograft root implantation demonstrating interrupted suture technique with Teflon felt support to prevent bleeding and allograft dilatation. Homograft is inverted to reduce chances of leaflet injury. Valve sizer assures adequate length of felt to avoid ``pursestringing'' of allograft tissue.

Postoperative Echocardiographic Evaluation
Two-dimensional, color-guided Doppler echocardiography was performed in 66 of 80 patients. Echocardiographic data were analyzed for grade of aortic regurgitation, mean and peak pressure gradients across the valve, aortic valve area, and valve area index (cm²/m² body surface area) whenever possible. Degree of aortic regurgitation was quantitated as follows: grade 0, no regurgitation; grade 1, mild regurgitation; grades 2 and 3, moderate regurgitation; and grade 4, severe aortic regurgitation.

The mean interval between operation and the last echocardiographic examination for the 66 patients was 40.0 ± 30.6 months. For patients having infracoronary implantation, this interval was 54.2 ± 29.6 months versus 21.8 ± 21.1 months for those having full root replacement (p = 0.0001). Serial echocardiograms in the same patient were available for analysis in 48 patients (infracoronary [n = 24] and root replacement [n = 24]). These serial echocardiograms were performed at a mean of 46 months after the operation.

Follow-up Analysis
Patient contact was made by telephone, letter, physician or personal interview, and examination in 55 patients (69%). Nine patients were lost to follow-up and could not be contacted. Sixteen patients either had the valve explanted or died.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
In the 80 patients having cryopreserved aortic valve allograft implantation (46 infracoronary and 34 root replacement), eight of the infracoronary valves and one of the root replacements have been explanted a mean of 22 months from the time of insertion. Reasons for explantation are given in Table 1. There have been five hospital and two late deaths in the entire series (6.3%), all occurring in the infracoronary group of patients. Three of the five hospital deaths were in patients having aortic valve replacement for endocarditis with root abscess. Both late deaths were noncardiac-related. Although the differences were not statistically significant (p = 0.07), there was a trend toward better New York Heart Association class for root versus infracoronary replacements (infracoronary class 1, 75% of patients; class 2, 17%; and class 3, 8% versus root class 1, 96% and class 2, 4%).

View larger version (34K): [in this window] [in a new window]   Fig 2. . (A) Mean systolic echocardiographic (ECHO) gradient as a function of valve size for the infracoronary allograft. (B) Mean systolic gradient as a function of valve size for the allograft root.

View larger version (16K): [in this window] [in a new window]   Fig 3. . Actuarial freedom (of infracoronary and root allografts) from echocardiographic grade 3 and 4 valvular insufficiency or explantation. Freedom from grade 3 through 4 aortic insufficiency (AI) or explantation for root allograft is 96% versus 60% for infracoronary allograft at 7 years.

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

Somewhat disappointing results with the antibiotic-sterilized 4°C allograft were reported by Ross [15], in which approximately 50% of these valves had to be replaced by the 11th year. In 1988 McGiffin and associates [16] reported excellent experience with the cryopreserved infracoronary homograft and described a meticulous procurement and preservation technique that resulted in a freedom from reoperation for any reason (endocarditis, leaflet degeneration, technical malalignment) of 89% at 10 years [16].

An update of O'Brien and colleagues' experience in 1991 [3] continued to stress the superiority of the cryopreserved allograft over those stored at 4°C. Freedom from moderate or severe aortic insufficiency at 14 years was 50% for the valve stored at 4°C and 78% for the cryopreserved valve. These differences were not statistically significant. However, freedom from reoperation at 14 years was significantly better for the cryopreserved allograft, ie, 95% versus 67% for antibiotic-sterilized valves (p = 0.001). The freedom from assumed structural valve deterioration at 14 years was 51% and 85%, respectively (p = 0.000003) [3]. The limitation of these observations was that they encompassed a clinical evaluation in all patients but color-flow echocardiographic evaluation to determine valve performance in an undisclosed number. A more sobering report of homograft valve function was presented by Grunkemeier and Bodnar [17] in which the worldwide literature on allograft subcoronary implantations was reviewed. With the exception of O'Brien's series, performance (as measured by freedom from structural valve deterioration) of the cryopreserved valve was about the same as that of the antibiotic-sterilized 4°C valve.

Daicoff and colleagues [2] first noted progression of aortic insufficiency determined by color-flow Doppler echocardiography in a small group of subcoronary allograft implantations. In their series no patient had grade 2 or greater aortic insufficiency early after implantation, but late evaluation demonstrated that 80% had grade 2 or greater insufficiency, and in 40% of these patients the severity was of grade 3 or 4. Our experience with the subcoronary implanted allograft has been similar, although not quite as extreme as that of Daicoff and colleagues [2]. Unlike Daicoff and colleagues, we employed the Ross modification of retaining the allograft noncoronary sinus to maintain the partial cylinder geometry.

In a recent series reported by Kirklin and associates [1], the 8-year freedom from presumed leaflet failure (explantation or grade 3 or 4 aortic insufficiency) in patients 20 to 50 years of age after infracoronary implantation was 75% but did not include patients having explantation secondary to technical problems with leaflet or root malalignment. Kirklin and associates noted that cryopreserved homograft valves perfectly competent early after operation frequently were observed to have mild asymptomatic insufficiency in the ensuing 5 years. Experience with homograft replacement of the aortic valve using a full root implantation was insufficient in this and Daicoff and associates series to determine whether this latter technique would provide freedom from late aortic insufficiency. Nevertheless, Daicoff and associates did note progressive, unexplained regurgitation at late follow-up in 3 of 14 patients with complete roots, but in none was it severe and only in 1 was it moderate [2].

Although the development of aortic insufficiency in the infracoronary implantation group (early grade 2 or greater in 28% of patients progressing later to 46% of patients) in the present study was not entirely unexpected, the late observation of any significant aortic insufficiency in the complete root replacement group was surprising. In this series, 14% of root implantation patients had grade 2 aortic insufficiency at a mean interval of 22 months after operation. None of these patients had grade 2 insufficiency early after operation. However, as a group, the difference in performance between subcoronary and complete root replacement patients was substantial, with 19% of the subcoronary implantation patients versus 3% of the root replacement patients having grade 3 or 4 aortic insufficiency at late follow-up. The 1 patient with grade 3 aortic insufficiency seen late after root replacement had staphylococcal endocarditis and required explantation for this reason. A limitation of our series is the shorter length of follow-up for the root replacement patients compared to those having subcoronary implantations (54 months versus 22 months), and this may significantly affect long-term comparisons. The fact that 28% of the subcoronary implantation patients and none of the root replacement patients had grade 2 or greater aortic insufficiency within 3 months of operation probably will be prognostic of better, although not perfect, performance of the root implantation technique late after operation.

The excellent hemodynamic function of both the subcoronary and root allografts has been noted before [13]. In this study and that of Daicoff, gradients across the root were approximately one half that of the subcoronary allograft. This difference was present both early and late after implantation, indicating that resolution of the retained muscular septum over time does not result in improved hemodynamic function of the infracoronary allograft.

As noted by Grunkemeier and Bodnar [17], the numerous methods of procurement and preservation employed over years of allograft use make interpretation of reported results difficult. Since 1988, all allograft valves used by O'Brien and colleagues [9] have originated from organ donors and have been cryopreserved 2 to 8 hours after donor death. Such a precise procurement and preservation program might possibly explain the superior results noted in their series. In our own series, except for patients early in the experience, all valves were procured from living organ donors and prepared by one technique similar, although not identical, to that of O'Brien and colleagues.

The technical difficulty and complexities of implantation using the infracoronary or freehand technique have been described in detail previously [5]. The most common cause of early (and probably late) insufficiency using the subcoronary implantation technique is the geometric asymmetry of the recipient's aortic annulus. This is especially true in situations of congenital aortic stenosis [7], where the partial cylinder of the freehand valve is not adequate protection against homograft annular and leaflet distortion, resulting in central valvular incompetence. In addition, slight degrees of malrotation at the time of insertion also may produce an unsatisfactory result. Others have noted loss of leaflet elastic extensibility over time in the 4°C antibiotic-sterilized allograft valves [18]. Such changes may explain problems with leaflet coaptation years after implantation.

To maximize the protective effect of the full cylinder against aortic insufficiency, Ross [6] introduced complete root replacement using a homograft in 1965. Since that time, it has been used effectively, particularly in situations of aortic valve and root endocarditis [19]. In 1989 O'Brien and associates [4] introduced the intraaortic ``inclusion'' cylinder technique, incorrectly described as ``mini-root implantation.'' The intraaortic cylinder has both advantages and disadvantages. The major advantage is that the host aorta affords protection from suture line bleeding, especially at the native annulus. Its major disadvantage is that the wrap itself may produce commissural misalignment or exaggerate slight distortions of the native annulus secondary to variations in geometry between the allograft and host annulus. This prevents perfect cusp coaptation and may result in unacceptable degrees of aortic insufficiency. If suture line bleeding produces hematoma between the aortic wrap and the homograft, leaflet distortion or even separation of the coronary anastomoses may occur. Complications related to the left main or right coronary anastomosis are potentially serious problems related to the whole complexity of the operation, regardless of whether a full root or intraaortic cylinder is used. One of us (E.L.J.) has preferred the full root replacement to avoid complications of the intraaortic cylinder listed above. To reduce the risk of proximal suture line bleeding, a carefully measured felt strip incorporated into the homograft annulus by interrupted 3-0 Prolene sutures is used, which adds strength to the cryopreserved aortic root and hopefully may prevent progressive dilatation associated with annular-aortic ectasia.

Our experience with the cryopreserved aortic homograft has significant implications for use and evaluation of the pulmonary autograft. First, like the freehand allograft, the pulmonary autograft used any way other than as a full cylinder does not function well. Unfortunately, selection of the pulmonary autograft as a valve substitute dictates double-valve replacement for single-valve disease, because an allograft must be used in the pulmonary position. As with the allograft, unanswered questions of satisfactory function related to the pulmonary autograft are of great concern. Performance of this complex operation probably should be limited to designated centers worldwide until long-term results are apparent in a carefully controlled pulmonary autograft registry. This would avoid the confusion historically surrounding allograft replacement (4°C versus cryopreserved, freehand versus intraaortic cylinder versus complete root) and allow a more precise evaluation of the autograft in comparison with existing valvular prostheses.

Although excellent early results with the pulmonary autograft have been reported by Ross [20], Kouchoukos [21], Elkins [22–24], and their colleagues, only Ross and associates' series may truly reflect what may be expected long-term of this ``relatively'' new technique. Unfortunately, echocardiography has not been employed routinely in Ross and associates' series to evaluate this large group of patients. Other excellent surgeons already have noted problems with the pulmonary autograft for elective aortic valve replacement. Pacifico and associates [25] recently have described the necessity for wrapping the pulmonary autograft with pericardium to prevent dilatation and valvular insufficiency in adult patients without a prior cardiac operation undergoing aortic valve replacement.

In summary, use of the cryopreserved allograft for routine aortic valve replacement is probably not warranted. Its advantages must be weighed against its recently discovered disadvantages. Subcoronary implantation of the partial cylinder in the freehand style is too frequently subject to distortion and commissural malalignment, resulting in unacceptable degrees of early and late insufficiency as demonstrated in this report. Its use in this fashion should now be abandoned. In an attempt to improve upon the disappointing results with the subcoronary procedure, complete root replacement has become our operation of choice when the allograft valve offers clear superiority over other existing prostheses. As suggested in one other report [2] and confirmed by the present study, even the allograft root with its distinct superiority to the freehand valve must be shown to be free of leaflet changes (degeneration or loss of elasticity) over longer periods of observation.

	Acknowledgments

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
We express our gratitude to Paula Turner for technical assistance.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 
Presented at the Forty-first Annual Meeting of the Southern Thoracic Surgical Association, Marco Island, FL, Nov 10–12, 1994.

Address reprint requests to Dr Jones, 1365 Clifton Rd NE, Atlanta, GA 30322.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Acknowledgments References

 

1. Kirklin JK, Smith D, Novick W, et al. Long-term function of cryopreserved aortic homografts: a ten year study. J Thorac Cardiovasc Surg 1993;106:154–66.[Abstract]
2. Daicoff GR, Botero LM, Quintessenza JA. Allograft replacement of the aortic valve versus the miniroot and valve. Ann Thorac Surg 1993;55:855–9.[Abstract]
3. O'Brien MF, McGiffin DC, Stafford EG, et al. Allograft aortic valve replacement: long-term comparative clinical analysis of the viable cryopreserved and antibiotic 4°C stored valves. J Cardiac Surg 1991;6(Suppl 4):534–43.[Medline]
4. O'Brien MF, McGiffin DC, Stafford EG. Allograft aortic valve implantation: techniques for all types of aortic valves and root pathology. Ann Thorac Surg 1989;48:600–9.[Abstract]
5. Jones EL. Freehand homograft aortic valve replacement-the learning curve: a technical analysis of the first 31 patients. Ann Thorac Surg 1989;48:26–32.[Abstract]
6. Ross DN. Aortic root replacement with a pulmonary autograft-current trends. J Heart Valve Dis 1994;3:358–60.[Medline]
7. O'Brien MF. Aortic valve implantation techniques-should they be any different for the pulmonary autograft and the aortic homograft? [Editorial]. J Heart Valve Dis 1993;2:385–7.[Medline]
8. McGiffin DC, O'Brien MF. A technique for aortic root replacement by an aortic allograft. Ann Thorac Surg 1989;47:625–7.[Abstract]
9. O'Brien MF, Johnston N, Stafford G, et al. A study of the cells in the explanted viable cryopreserved allograft valve. J Cardiac Surg 1988;3(Suppl 3):279–87.[Medline]
10. Ross D. Technique of aortic valve replacement with a homograft: orthotopic replacement. Ann Thorac Surg 1991;52:154–6.[Abstract]
11. Ross DN. Homograft replacement of the aortic valve. Lancet 1962;2:487.[Medline]
12. Barratt-Boyes BG. Homograft aortic valve replacement in aortic incompetence and stenosis. Thorax 1964;19:131.[Free Full Text]
13. Jaffe WM, Coverdale HA, Roche AHG, et al. Rest and exercise hemodynamics of 20 to 23 mm allograft, Medtronic intact (porcine), and St. Jude Medical valves in the aortic position. J Thorac Cardiovasc Surg 1990;100:167–74.[Abstract]
14. Yankah AC. Surgical management of infective endocarditis: pulmonary autograft or allograft? J Heart Valve Dis 1994;3:380–3.[Medline]
15. Ross D. Applications of homografts in clinical surgery. J Cardiac Surg 1987;2(Suppl 1):175–83.[Medline]
16. McGiffin DC, O'Brien MF, Stafford EG, et al. Long-term results of the viable cryopreserved allograft aortic valve: continuing evidence for superior valve durability. J Cardiac Surg 1988;3(Suppl):289–96.[Medline]
17. Grunkemeier GL, Bodnar E. Comparison of structural valve failure among different `models' of homograft valves. J Heart Valve Dis 1994;3:556–60.[Medline]
18. Christie GW, Barratt-Boyes BG. Identification of a failure mode of the antibiotic sterilized aortic allograft after 10 years: implications for their long-term survival. J Cardiac Surg 1991;6:462–7.[Medline]
19. Ross DN. Aortic root replacement with a cardiac allograft: the infected aortic root. In: Yankah AC, Hertzer R, Miller DC, et al, eds. Cardiac valve allografts 1962–1987. New York: Springer, 1988:167.
20. Ross DN, Jackson M, Davies J. Pulmonary autograft aortic valve replacement: long-term results. J Cardiac Surg 1991;6(Suppl):529–33.[Medline]
21. Kouchoukos NT, Davila-Romain VG, Spray TL, et al. Replacement of the aortic root with a pulmonary autograft in children and young adults with aortic valve disease. N Engl J Med 1994;330:1–6.[Abstract/Free Full Text]
22. Elkins RC. Pulmonary autograft-the optimal substitute for the aortic valve? [Editorial]. N Engl J Med 1994;330:59–60.[Free Full Text]
23. Elkins RC, Knott-Craig CJ, Razook JD, et al. Pulmonary autograft replacement of the aortic valve in the potential parent. J Cardiac Surg 1994;9(Suppl):198–203.[Medline]
24. Elkins RC. Pulmonary autograft: expanding indications and increasing utilizations [Editorial]. J Heart Valve Dis 1994;3:356–7.[Medline]
25. Pacifico AD, Kirklin JK, McGiffin DC, et al. The Ross operation-early echocardiographic comparison of different operative techniques. J Heart Valve Dis 1994;3:365–70.[Medline]

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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Jones, E. L. Articles by Shen, Y. Search for Related Content PubMed PubMed Citation Articles by Jones, E. L. Articles by Shen, Y.