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Ann Thorac Surg 1997;64:659-663
© 1997 The Society of Thoracic Surgeons

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Original Article: Cardiovascular

The Aortic Homograft: Evolution of Indications, Techniques, and Results in 107 Patients

Section of Cardiac and Thoracic Surgery, St. Joseph Mercy Hospital, Ann Arbor, Michigan

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Background. Homograft aortic valve replacement has been performed in 107 patients during the past 7 years. Two primary methods of implantation were used (intraaortic and root replacement). Results of both methods are presented.

Methods. Intraaortic implantation (subcoronary or cylinder technique) was performed in 36 patients (mean age, 54 years) for aortic stenosis or regurgitation (31 patients) and endocarditis (5 patients). Aortic root replacement was performed in 71 patients (mean age, 62 years). The majority (58 patients) had complex root pathologies such as ascending aneurysm, dissection, or prosthetic endocarditis with annular destruction. Early results were assessed with intraoperative or predischarge echocardiography; annual echocardiograms provided long-term follow-up. Left ventricular mass was calculated in patients with long-standing pathology for whom preoperative and postoperative data were available.

Results. Early valvular insufficiency was documented in 16 of the 36 intraaortic implants (44%); 9 of these have had progression of the insufficiency. Of the 20 patients who had trivial or no early insufficiency, significant insufficiency has developed in 7 and mild insufficiency has developed in 5. Calculation of left ventricular mass revealed a mean reduction of 11% at 1 year. There has been no mortality, endocarditis, or homograft-related reoperation in the intraaortic group with a mean follow-up of 50 months. The root replacement group had a hospital mortality of 17%. The cardiac pathology was limited to the aortic valve in 12 patients; mortality in this subset was zero. There has been no significant early or late postoperative valvular insufficiency in the 59 surviving patients. More rapid left ventricular mass reduction was seen in this group with a 26% mean reduction within 1 year. A mean follow-up of 32 months in the root replacement group has seen no homograft-related reoperations.

Conclusions. Although the lack of early mortality in the intraaortic group makes this technique appealing, the high incidence of early insufficiency with the realistic expectation of progression has led to our abandonment of the intraaortic technique. Homograft aortic root replacement confers a higher mortality based on the severity of aortic pathology, but offers excellent long-term hemodynamics in any patient. We have expanded our indication for homograft root replacement to include patients with isolated valvular disease rather than reserving it for those patients with extensive root pathology.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
See also page 663.

See also page 664.

As cryopreservation techniques have increased the availability of homograft valves and fostered a revival of use during the past decade, reports of various implantation techniques and results have been presented with differing outcomes. Learning curves for implantation techniques and comparison of early and midterm results have generated considerable discussion about preferred implantation techniques, as well as exploring the definitive indications for their use. This report reviews our series of homograft valves and the evolution of our approach.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Patient Population
Since May 1989, 107 patients have undergone cryopreserved aortic homograft valve implantation, representing 15% of aortic valve replacements at St. Joseph Mercy Hospital during that time period. Thirty-six patients (26 men and 10 women) underwent intraaortic (subcoronary or cylinder) implantations. The age range in this group was 22 to 68 years, with a mean age of 53.5 years. Thirty-two were scalloped subcoronary and four were cylinders. Two of these patients were undergoing redo procedures (5.5%). Twelve of the 36 patients underwent concomitant cardiac procedures (Table 1). Indications for replacement are specified in Table 2.

Operative Technique
All patients were operated on through a full median sternotomy with cardiopulmonary bypass at moderate hypothermia (30 to 32°C) and intermittent cold blood cardioplegia, both antegrade and retrograde. In the early portion of the series, implantation technique was based on anatomic and pathologic findings and surgeon preference. During the past 2 years, however, root replacement has been used in all 30 homograft recipients. In the intraaortic group of 36 patients, 32 had scalloped subcoronary implantations. The homograft was sized 1 to 3 mm smaller than the native annulus and was placed orthotopically. Sutures of 4-0 polypropylene were placed at the lowest point of each sinus of Valsalva. The valve was then usually inverted and the proximal suture line completed in a running fashion. The valve was then everted and the commissural posts anchored, as Stelzer and Elkins [1] note, 5 to 10 mm distal to the top of the native commissures. The right and left coronary sinuses were scalloped beneath the ostia, the noncoronary sinus was left intact, and a running distal suture line was completed with 4-0 polypropylene. Dead space in the noncoronary sinus was obliterated by including homograft adventia in the aortotomy closure.

The 4 patients who underwent cylinder implantation had all sinuses maintained intact. The coronary ostia were reimplanted into button holes at the donor ostia using 5-0 polypropylene. The proximal and distal suture lines were carried out with 4-0 polypropylene.

In the 71 patients who underwent homograft root replacement, the extent of aortic annular debridement and resection was dictated by the etiology of the valvular lesion. The homograft was inserted orthotopically. The proximal suture line was carried out with 4-0 polypropylene in running or interrupted fashion; native coronary button anastomosis was done with 5-0 polypropylene, and the distal suture line was completed with running 4-0 suture. More extensive procedures were performed in patients with native and prosthetic endocarditis with septal, atrial wall, and mitral involvement.

At the completion of the operative procedure, transesophageal echocardiogram was used to assess valve and cardiac function in 66% of the root replacements and 58% of the intraaortic patients.

Follow-up
All surviving patients are followed up with a surface echocardiogram at 1 month postoperatively. Attempts are made to continue to follow up these patients at yearly intervals with clinical evaluation and surface echocardiography; however, some have been lost to follow-up.

Valvular regurgitation is quantified on a scale of 0 to 4+. Trivial or no regurgitation is graded as 0; mild is graded as 1+; moderate is graded as 2+; moderately severe is graded as 3+; and severe regurgitation is graded as 4+.

Homograft conduits were provided by CryoLife Cardiovascular Inc (Marietta, GA). They were stored and available in a liquid nitrogen freezer in the operating suite.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Intraaortic Patients
All patients in the intraaortic group survived the procedure, and the mean follow-up is 50 months. Two patients required reoperation; 1 patient had acute aortic regurgitation on the first postoperative day necessitating reexploration. Disruption of the distal suture line had occurred at a commissural post; this was resuspended and the patient continues to do well 6 years postoperatively with mild regurgitation. A second patient underwent mitral valve replacement for progressive mitral stenosis 5 years after homograft aortic valve replacement. Moderate regurgitation had developed in the homograft, which was replaced at the same time; both replacements were with mechanical valves.

All patients were in New York Heart Association functional class I or II (30 and 6 patients, respectively) at the last date of follow-up (Fig 1). In the group of 5 patients with native valve endocarditis there has been no recurrence of infection; none of the other 31 patients have developed homograft endocarditis. There have been no embolic events.

View larger version (37K): [in this window] [in a new window]   Fig 1. . Preoperative (PREOP) and postoperative (POSTOP) New York Heart Association functional class: intraaortic group.

Therefore, in the intraaortic group of 36 patients, 8 have been lost to follow-up. Of the 28 patients still being followed up, 24 demonstrate progression of aortic regurgitation (14 patients to 2+ or greater).

Interestingly, mean gradients of 10 to 22 mm Hg are present in 11 patients. Data for left ventricular mass calculations were available in half of the patients with preoperative chronic valvular disease. In those patients, mean reduction in left ventricular mass of 11% was seen at 1 year (mean change, 44 g), reaching 21% mean reduction at 3 years (mean change, 78 g).

Root Replacement
There were 12 deaths in this group of 71 patients for a hospital mortality of 17%. Ten of the 12 deaths were in patients undergoing redo procedures. Thirty percent of the overall 71 patients had redo procedures. After discharge, there was one early death of unknown cause and there were three late deaths: one of new-onset endocarditis with multisystem organ failure at 7 years postoperatively, a second of unknown cause, and a third of lung cancer. The mean follow-up in this group is 32 months.

Four patients have undergone reoperation. One underwent early (3 weeks) repeat root replacement for persistent endocarditis, requiring wider debridement of the base of the heart and septum as well as mitral valve replacement. Two patients underwent reoperation for a false aneurysm at the suture line, and the fourth patient was reoperated on 2 days postoperatively for suture line dehiscence. All survived reoperation.

Functional class analysis at the time of last follow-up revealed 48 patients in class I, 9 in class II, 1 in class III, and 1 patient in class IV, as shown in Figure 2. Functional class improvement occurred in all but 1 patient, excluding 2 patients with Marfan's syndrome who started and remained in class I.

View larger version (38K): [in this window] [in a new window]   Fig 2. . Preoperative (PREOP) and postoperative (POSTOP) New York Heart Association functional class: root replacement group.

Embolic events have not been documented in any patient; there is one questionable event of amaurosis fugax in a patient with known arteriovenous malformations.

Echocardiographic evaluation of valve function in the root replacement group reveals that in the 51 patients with grade zero early regurgitation, 9 patients are graded as mild (1+) at 4 years postoperatively. Forty-four patients have grade zero aortic regurgitation at a mean follow-up of 32 months (this includes 2 patients with mild aortic regurgitation at the time of operation). Two patients in this group have mean gradients of 10 to 20 mm Hg. In 20 patients in this group for whom data were available, left ventricular mass diminished 26% within 1 year of operation (mean change, 105 g).

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
During the past 10 years there has been a resurgence of interest in and use of homograft valves in cardiac operations. The initial reports of Donald Ross [2] and Sir Brian Barratt-Boyes [3] stimulated interest in these valves, but given the progressive availability of mechanical and xenograft valves, homograft valve use was limited. As knowledge of the limitations of valve substitutes grew and complications clarified including infection, emboli, and xenograft degeneration, the concept of homograft valves became more appealing and subject to reconsideration. Along with this, cryopreservation techniques enabled increased availability and storage of valves, improving access to these substitutes that were thought to be superior to the fresh homografts [4, 5].

Randolph and colleagues [6] at the University of Oklahoma were instrumental in fostering the resurgence with their superb early reports. Subsequent reports by Jones [7] and Doty and co-workers [8] furthered the enthusiasm for these valves. Larger series with longer follow-up such as those from Matsuki and colleagues [9] with 555 patients and O'Brien and associates [10] with 534 patients confirmed the efficacy of these valves on a larger number of patients. Those using these valves championed the flow characteristics and excellent hemodynamics, freedom from embolic events without anticoagulation, freedom from early infection, and freedom from degeneration, especially with cryopreservation of the valves. The versatility of the homograft root in situations of complex pathology of the valve, annulus, aorta, and base of the heart furthered its usage.

This series of 107 patients, initiated in 1989, was in response to the resurgence of interest in homografts. Early in this experience, the intraaortic implantation technique was used, except in the setting of extensive infection affecting the annulus, septum, and base of the heart, or in those patients with aneurysmal disease or dissection. The vast majority of these were subcoronary implants, 32, with four cylinders being done. From the perspective of survival, all 36 patients survived and although 8 are lost to follow-up, the remainder continue to be followed up. Although no embolic events or recurrent endocarditis occurred and functional improvement has occurred, there is an obvious occurrence and progression of aortic regurgitation when these techniques are used; moderate regurgitation develops in 50% of those followed up. Although there have been no reoperations expressly for regurgitation at a mean follow-up of 50 months, this worrisome finding altered our approach to homograft use. Jones and colleagues [11] have already shown that late aortic regurgitation occurs in 46% of intraaortic patients and in the series by Daicoff and colleagues [12], 80% of the freehand scalloped patients had at least moderate regurgitation. Similarly, Kirklin and associates [13] note in their series a progression of regurgitation of up to 80% at 5 years in a group of intraaortic implants with competent valves at the time of implant. It is important to realize that the technical challenges in using the infracoronary approach have been addressed by many [7, 11, 14–16] and although, as noted by Grunkemeier and Bodnar [17], there are multiple variables when attempting to compare series of homografts, it is readily apparent in this series and others that the intraaortic homograft does not provide optimal, consistent long-term hemodynamic performance.

The 71 patients with homograft root replacements represent a more challenging and complex group of patients. The hospital mortality of 17% reflects the magnitude of the pathologic process. Five of the 12 deaths had extensive root infections, five deaths were in the dissection group and 1 valve–aneurysm patient died. The only death in the isolated valve disease group (n = 13) was in a patient who had coronary artery disease and severe extracranial obstructive vascular disease. He suffered a massive cerebral event. The other 12 patients in this group had no other cardiac pathology and had no mortality. This compares quite favorably with the 2.7% mortality in 268 patients who underwent nonhomograft isolated aortic valve replacement at our institution during the same time frame.

Follow-up of this complex group reveals consistent functional improvement. There have been no documented embolic events; 1 patient had transient amaurosis fugax without an obvious cause late postoperatively. One patient had development of endocarditis on his homograft valve 7 years after operation and is the only patient in the entire series of 107 patients in whom valve infection developed and the only 1 of the 25 patients with native or prosthetic endocarditis in whom endocarditis developed again.

From the perspective of valve function this group clearly shows minimal regurgitation (Fig 3). Of the 53 patients with late or ongoing follow-up, 44 have grade zero regurgitation at a mean follow-up of 32 months. Only 9 patients (17%) have mild regurgitation.

View larger version (18K): [in this window] [in a new window]   Fig 3. . Freedom from significant aortic regurgitation. (AI = aortic insufficiency.)

As Mark O'Brien [18] states, "after 24 years' experience with homograft aortic valve replacement, the author of this editorial considers that the subcoronary implantation technique for the homograft is an inferior one. The precise surgical decisions as to whether to invert or evert, rotate, and retain the non-coronary aortic wall are difficult and, to many surgeons, too confusing. Coupled with the added problems of an asymmetrical host aortic root, the final reliable, consistently acceptable hemodynamic results with subcoronary implantation are not being attained in the long term."

In our experience, we have not been able to provide optimal hemodynamic results with the intraaortic use of the homograft. Therefore, although these results are not long term, and on-going diligent follow-up is imperative, we now use homograft valves only as root replacements. This approach offers an excellent outlook for patients with complicated valvular and aortic disease and for older patients with isolated valve disease. If patients require or desire a tissue valve, homograft aortic root replacement mortality parallels that of our other valve replacement series and offers anticipated greater freedom from reoperation.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Presented at the Forty-third Annual Meeting of the Southern Thoracic Surgical Association, Cancun, Mexico, Nov 7–9, 1996.

Address reprint requests to Dr Prager, 5325 Elliott Dr, Suite 102, PO Box 972, Ann Arbor, MI 48106-0972.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 

1. Stelzer P, Elkins RC. Homograft valves and conduits: applications in cardiac surgery. Curr Probl Surg 1989;26:431.
2. Ross DN. Homograft replacement of the aortic valve. Lancet 1962;2:487.[Medline]
3. Barratt-Boyes BG. Homograft aortic valve replacement in aortic incompetence and stenosis. Thorax 1964;19:131–50.[Free Full Text]
4. O'Brien MF, Stafford EG, Gardner MJH, et al. A comparison of aortic valve replacement with viable cryopreserved and fresh allograft valves, with a note on chromosomal studies. Thorac Cardiovasc Surg 1987;94:812–23.
5. 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 Card Surg 1988;3:289–96.[Medline]
6. Randolph JD, Toal K, Stelzer P, et al. Aortic valve and left ventricular outflow tract replacement using allograft and autograft valves: a preliminary report. Ann Thorac Surg 1989;48:345–9.[Abstract]
7. Jones EL. Freehand homograft aortic valve replacement—The learning curve: a technical analysis of the first 31 patients. Ann Thorac Surg 1989;48:19–25.[Abstract]
8. Doty DB, Michielon G, Wang N-D, Cain AS, Millar RC. Replacement of the aortic valve with cryopreserved aortic allograft. Ann Thorac Surg 1993;56:228–36.[Abstract]
9. Matsuki O, Robles A, Gibbs S, et al. Long term performance of 555 aortic homografts in the aortic position. Ann Thorac Surg 1988;46:187–90.[Abstract]
10. 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 valve. J Card Surg 1991;6:534–43.[Medline]
11. Jones EL, Shah VB, Shanervise JS, et al. Should the freehand allograft be abandoned as a reliable alternative for aortic valve replacement? Ann Thorac Surg 1995;59:1397–404.[Abstract/Free Full Text]
12. Daicoff GR, Botero LM, Quintessenzon JA. Allograft replacement of the aortic valve versus the miniroot and valve. Ann Thorac Surg 1993;55:855–9.[Abstract]
13. Kirklin JK, Smith D, Novick W, et al. Long-term function of cryopreserved aortic homografts. J Thorac Card Surg 1993;106:154–66.[Abstract]
14. Hopkins R. Allograft aortic valve replacement for bicuspid aortic valves with 180-degree coronary ostia. Ann Thorac Surg 1989;47:930–2.[Abstract]
15. O'Brien MF, McGiffin DC, Stafford EG. Allograft aortic valve implantation: techniques for all types of aortic valve and root pathology. Ann Thorac Surg 1989;48:600–9.[Abstract]
16. Dearani JA, Orszulak TA, Daly RC, et al. Comparison of technique for implantation of aortic valve allografts. Ann Thorac Surg 1996;62:1069–75.[Abstract/Free Full Text]
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. 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]

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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 Author home page(s): Richard L. Prager Bobby Kong James P. Byrne Otto Gago Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Prager, R. L. Articles by Gago, O. Search for Related Content PubMed PubMed Citation Articles by Prager, R. L. Articles by Gago, O. Related Collections Related Article