Ann Thorac Surg 2009;88:1365-1366. doi:10.1016/j.athoracsur.2008.12.100
© 2009 The Society of Thoracic Surgeons
How To Do It
Re-Do Aortic Root Replacement After an Allograft Aortic Root Replacement
Marian Vrtik, MBBS,
Peter J. Tesar, FRACS*
Department of Cardiothoracic Surgery, The Prince Charles Hospital, Chermside, Queensland, Australia
Accepted for publication December 29, 2008.
* Address correspondence to Dr Tesar, Department of Cardiothoracic Surgery, The Prince Charles Hospital, Rode Rd, Chermside, Queensland, 4032, Australia (Email: petertesar{at}health.qld.gov.au).
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Abstract
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Structural degeneration of allograft aortic root is a global process. In addition to valvular degeneration, the allograft wall calcification poses a risk of systemic calcific embolization and late phase anastomotic aneurysm formation and rupture (anecdotal). Furthermore, the valve annulus is often small, and the tissues are rigid making the implantation of an adequately sized prosthesis within the allograft wall difficult. To avoid these issues, we routinely perform re-do aortic root replacement with either a mechanical valve conduit or bio-root composite graft. The technique has been successfully used in 22 consecutive patients with no operative mortality and minimal morbidity.
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Introduction
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Free-standing allograft aortic root replacement became an established technique of aortic valve replacement [1]. The technique gained popularity due to the perceived advantages of improved immediate valve competence when compared with the subcoronary implantation technique [2]. Moreover, the technique allows correction for size and shape discrepancy between the homograft and the recipient root. The prosthesis is noiseless, has excellent hemodynamic properties, is associated with low incidence of thromboembolic events and is exceptionally resistant to the development of prosthetic valve endocarditis [3]. However, degeneration of the homograft aortic root is a global process affecting both the allograft valve and the allograft wall. In addition to often severe calcification of the allograft wall, the surgeon has to deal with dense peri-allograft adhesions during re-do surgery. We present a technique of re-do aortic root replacement with a mechanical aortic valved graft (ATS Open Pivot Aortic Valved Graft; ATS Medical, Minneapolis, MN) or a composite bio-root valved conduit (standard Perimount bio-prosthesis [Edwards Lifesciences, Irvine, CA] implanted into a zero porosity Dacron graft [Vascutek Ltd, Inchinnan, Scotland]), which has been successfully used in 22 consecutive patients by the senior author, Peter Joseph Tesar.
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Technique
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After a re-do sternotomy is performed, only the front of the heart is dissected out to expose the free wall of the right atrium, anterior aspect of the aorta, and left side of the aortic arch. Cardiopulmonary bypass is established with an aortic inflow cannula at the mid-arch level and a two-stage venous cannula in the right atrial appendage. The remainder of the dissection is performed while cooling the patient to 32° C. Initially, the right superior pulmonary vein is dissected out and a vent is placed into the left ventricular chamber. The front of the heart is dissected on the left side from the diaphragm to the pulmonary artery. The pulmonary artery is separated from the native aorta distally (beyond the homograft). The cross clamp is applied at the level of the base of the innominate artery. Retrograde cold crystalloid cardioplegia is administered every 20 minutes at dosage 50% greater than normal expectation. The aorta is divided 1 to 1.5 cm proximal to the cross clamp.
While separating the homograft from the host structures (ie, main pulmonary artery, right pulmonary artery, right atrium, and right ventricle) and mobilizing the coronary buttons, adherence to the following principles must be made. First, always dissect onto the homograft, in our experience either by using diathermy or a scalpel. Second, as it is dissected free a safe distance above the coronary buttons, the homograft is opened laterally along its length down towards the noncoronary sinus, thereby allowing safe identification of the coronary ostia from inside the allograft. The coronary buttons are mobilized and the dissection is carried down to the level of the previous annular suture line. Third, the suture line including any remaining allograft tissue is completely removed (Fig 1) using scissors, scalpel, and diathermy.
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Fig 1. Completely excised aortic root down to the level of the aortic annulus with mobilized right and left coronary buttons.
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After allograft removal, mechanical aortic-valved graft or composite bio-root valved conduit (bio-prosthesis implanted into a zero porosity Dacron graft [Vascutek Ltd]; vascular graft being 3 mm larger than the bioprosthetic valve) is implanted using single interrupted 2.0 Ticron sutures (C. R. Bard, Murray Hill, NJ) tied over a polytetrafluoroethylene felt strip. The coronary ostia are re-implanted in a standard fashion with 5.0 Prolene (Ethicon, Somerville, NJ). Bioglue (CryoLife Inc, Kennesaw, GA) is applied over the three suture lines.
The distal anastomosis is performed with 5.0 or 4.0 Prolene (Ethicon) over a polytetrafluoroethylene felt strip. The operative field is flooded with carbon dioxide. The left ventricular vent is turned off well before the distal suture line is completed to allow the heart and the graft to fill with blood. The air is removed from the heart through the distal suture line prior to its completion and through the graft itself with multiple needle holes (18 gauge), hemostasis occurring with protamine and subsequent Bioglue (CryoLife Inc) application. Both atrial and ventricular pacing wires are implanted. Cardiopulmonary bypass is discontinued after a protracted period of reperfusion.
Between June 2005 and January 2008, 22 consecutive patients underwent re-do allograft replacement using the previously described technique. There were 17 men and 5 woman included in the series. The mean age was 48 years (range, 21–79 years). Although not truly indicative of the natural history of the allograft aortic root replacement, the median time to reoperation in this select patient group was 14.3 years (range, 4–20 years). The indication for reoperation included structural deterioration of the allograft in 29 patients, infected endocarditis in 2 patients, and allograft wall degeneration with thromboembolic stroke in 1 patient. A mechanical-valved conduit was used in 17 patients and the bio-root valved conduit was used in 7 patients. The median valve size was 25 mm with the size range between 21 mm (1 patient only) and 27 mm. There was no hospital mortality. Major morbidity included one perioperative stroke with full recovery prior to hospital discharge. No permanent pacemakers were required.
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Comment
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When faced with reoperation of a degenerate allograft root, conventional wisdom was (and probably still is) to replace the allograft valve within the degenerate root for the apparent simplicity of the required operative design. However, in our experience, the surgeon is often faced with a severely calcified, nonpliable aortic root with a small-sized to medium-sized aortic annulus. Complete removal of all the calcified allograft tissue allows one to easily implant an adequately sized valved conduit avoiding the potential risks of patient prosthesis mismatch or paravalvular leak due to inadequately seated prosthesis. The series started when a 21-mm valve could not be introduced into the allograft annulus after valve excision, necessitating a full root replacement. Another patient, not included in this series, received an 18-mm mechanical valve implanted within the allograft wall, which subsequently had a severe paravalvular leak develop with hemolysis, requiring full root replacement. Furthermore, removal of the degenerate allograft wall prevents potential future complications such as allograft rupture and systemic embolism (anecdotal evidence). The perioperative results in our series compare favorably with previously published data. The range of operative mortality for re-do aortic valve replacement after previous allograft aortic valve replacement has been reported between 2.87% and 28.5% [2, 4–6]. Therefore, the previously described technique can be considered a safe and reproducible option available to a cardiac surgeon when dealing with this challenging subset of patients.
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References
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- Gula G, Ahmed M, Thompson R, Radley-Smith R, Yacoub M. Combined homograft replacement of the aortic valve and root with reimplantation of the coronary arteries Circulation 1976;53(Suppl 2):150.
- Okita Y, Francioci G, Matsuhi O, Nobles A, Ross DN. Early and late results of aortic root replacement with antibiotic-sterilized aortic homograft J Thor Cardiovasc Surg 1988;95:696-704.[Abstract]
- O'Brien MF, Harrocks S, Stafford EG, et al. The homograft aortic valve: a 29-year, 99.3% follow up of 1022 valve replacements J Heart Valve Dis 2001;10:334-345.[Medline]
- Thoralf MS, Rasmi N, Wong K, Radley-Smith R, Khaghani A, Yacoub MH. Reoperative aortic valve operation after homograft root replacement: surgical options and results Ann Thor Surg 1995;60:S95-S100.[Abstract/Free Full Text]
- Sadowski J, Kapelak B, Bartus K, et al. Re-operation after fresh homograft replacement: 23 years' experience with 655 patients Eur J Cardiothorac Surg 2003;23:996-1001.[Abstract/Free Full Text]
- Penta A, Qureshi S, Radley-Smith R, Yacoub MH. Patient status 10 or more years after "fresh" homograft replacement of the aortic valve Circulation 1984;70(Suppl 1):187-191.
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Abstract
Introduction
