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Ann Thorac Surg 1998;66:88-91
© 1998 The Society of Thoracic Surgeons

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Original articles: cardiovascular

Repeat aortic root replacement

^a Cardiac Surgical Unit, Massachusetts General Hospital and Mount Auburn Hospital, Harvard Medical School, Boston, Massachusetts, USA

Accepted for publication February 13, 1998.

Address reprint requests to Dr Tam, 300 Mount Auburn St, Suite 516, Cambridge, MA 02138

	Abstract

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Background. Aortic root replacement in patients who have undergone previous aortic root replacement presents a formidable technical challenge, which may lead to increased surgical mortality.

Methods. We reviewed our experience from January 1989 through November 1995. Seven consecutive patients (6 men and 1 woman) underwent eight repeat aortic root replacements. Mean follow-up was 19 months. Previous root replacement had been performed with homograft in 1 patient, with a bioprosthetic valve composite graft in 1 patient, and with a mechanical valve composite graft in 6 patients. The techniques used at the previous procedures were the Cabrol technique (2 patients), Bentall technique (3 patients), and the coronary button technique (3 patients). Reoperation was indicated for pseudoaneurysm formation in 4 patients and for endocarditis in the others.

Results. Aortic homografts were implanted in all patients with endocarditis and mechanical valve composite grafts were used in the others. In all reoperations, the coronary button technique was used. No procedures were done emergently. Concomitant procedures were performed in 2 patients, including mitral valve replacement and aortic arch aneurysm repair. One patient had recurrence of his endocarditis 36 months after operation because of continued intravenous drug use requiring a second successful homograft root replacement. There were no early deaths and one late death at 16 months after operation.

Conclusions. Repeat aortic root replacement, even in the setting of endocarditis, can be done with low mortality.

	Introduction

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In 1964, Wheat and coworkers [1] performed the first successful replacement of the entire ascending aorta and aortic valve in continuity by separate graft valve repair. Since then, numerous techniques have been described for aortic root replacement. In 1968, Bentall and De Bono [2] described a technique using a composite tubular graft containing a prosthetic valve with side-to-end reimplantation of the coronary artery ostia to replace the aortic root. Because many of the complications of this procedure involve the coronary arteries, in 1981 Cabrol and colleagues [3] used a second tube graft interposed between the coronary ostia, which was then attached side-to-side to the aortic composite valve graft to deal with issues of tension, poor exposure, and hemostasis at these anastomoses. They also created a fistula between the aortic wrap, as proposed by Bentall and De Bono, and the right atrium to drain oozing from the prosthesis. Various modifications of these techniques [4, 5], along with the introduction of homografts for root replacement have led to numerous reports of series of patients undergoing this procedure [6–8]. However, because of the relatively small number of patients requiring aortic root replacement for the second time, information in the literature on this topic is scarce. There will most likely be a growing number of patients presenting for repeat aortic root replacement in the future given the increased use of homograft root replacements and their late degeneration. The purpose of this review, therefore, is to analyze our own experience during a 6-year interval with this challenging group of patients with the intent of demonstrating that this can be done with low early and medium-term mortality and morbidity.

	Material and methods

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Patients
Between January 1989 and November 1995, eight consecutive repeat aortic root replacements were performed on 7 patients by five surgeons at the Massachusetts General Hospital and Mount Auburn Hospital. The records of all patients were examined. The mean age of patients at reoperation was 46.8 years (range, 23 to 69 years). There were 6 men and 1 woman. Two patients (25%) had clinical stigmata of Marfan’s syndrome; 4 had New York Heart Association functional class I status, 2 had class II status, and 2 had class III status. Reoperation was indicated for pseudoaneurysm formation in 4 patients and for active bacterial endocarditis in 4. Patients were considered to be in the active phase of endocarditis if they had clinical features of active infection, positive preoperative blood cultures, and gross and histologic intraoperative findings consistent with active infection [9].

Two patients presented with septic emboli. The mean duration of preoperative intravenous antibiotic treatment for cases of endocarditis was 9.3 days (range, 3 to 21 days). Minimal to no aortic insufficiency was noted except for 2 patients with endocarditis in which moderate aortic regurgitation along with moderate aortic stenosis was present.

Previous root replacement had been performed with composite mechanical valve graft in 6 patients, composite bioprosthetic valve graft in 1 patient, and aortic homograft in 1 patient. The techniques used at the previous procedures were the Cabrol technique [3] in two operations, the Bentall technique [2] in three, and coronary button (Carrel patch) technique [4, 5] in three. The mean interval between previous root replacement and repeat root replacement was 60.8 months (range, 5 to 200 months).

No procedures were done emergently. Associated procedures were undertaken in 2 patients, those being mitral valve replacement and aortic arch aneurysm repair.

Operative technique
A median sternotomy incision was used and inflow for cardiopulmonary bypass was obtained through the femoral artery. Venous cannulation was performed through either the femoral vein, right atrium (bicaval or two stage), or both. After cardiopulmonary bypass and systemic hypothermia were initiated, the aorta was cross-clamped just proximal to the innominate artery. Cold dilute blood or crystalloid cardioplegia was administered antegrade into the previously placed graft or directly into the coronary ostia and additional retrograde cardioplegia was used in 1 patient. Cardioplegia infusion was repeated at regular intervals. Deep hypothermia and 60 minutes of circulatory arrest were used for aortic arch repair and for 16 minutes in 1 other patient. Extensive excision of infected tissue was accomplished in all patients with endocarditis [10]. All previous graft material was debrided leaving coronary ostial buttons with mobilization of the proximal coronary arteries. Cryopreserved aortic homografts were sutured to the aortic annulus in the patients with endocarditis, and previously prepared composite mechanical valve grafts were inserted in the other patients. Three St. Jude valve prostheses and one Hall-Medtronic valve prosthesis were used. In all re-replacements, the coronary button technique for coronary artery reattachment was used. The mobilized ostial buttons were then reattached to the new graft side-to-end without difficulty [4, 5]. The distal ascending aorta was completely transected, the graft cut to appropriate length, and the distal aortic anastomosis performed end-to-end. In no instance was the aneurysm wall wrapped around the aortic graft because of the greater risk of false aneurysm development associated with this technique [4, 7, 11]. Mean cardiopulmonary bypass time was 289 minutes (range, 181 to 397 minutes) and mean aortic cross-clamp time was 186 minutes (range, 140 to 232 minutes).

Follow-up and data analysis
Follow-up information was available for all hospital survivors and was achieved by examination or by correspondence with the patient and referring physician. The date of last inquiry was between June 1995 and December 1995. Mean follow-up was 19.4 months (range, 5 to 41 months).

	Results

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Mortality
There was no early mortality. Infection of the composite St. Jude valve graft prosthesis developed from an unknown source 16 months after repeat aortic root replacement for sterile pseudoaneurysm in 1 patient. His initial operation 3 years earlier was a composite graft replacement using the Cabrol technique to treat a ruptured ascending aortic aneurysm due to Marfan’s syndrome. He presented to another institution with sepsis and multiorgan system emboli from a large aortic root abscess. A homograft root replacement was performed but he could not be weaned from cardiopulmonary bypass and the patient died in the operating room.

Morbidity
Postoperative hemorrhage requiring reoperation developed in 1 patient (12.5%). He had undergone repeat root replacement for the third time with aortic homograft after developing Staphylococcus aureus endocarditis. He was reexplored 4 hours postoperatively without a particular bleeding site identified. The same patient suffered the only (12.5%) perioperative stroke in this series. He experienced a parietal infarct with left lower extremity paresis 1 week postoperatively. Two patients (25%) required intraoperative intraaortic balloon pump placement, but none required assisted circulation. No patient was reoperated on for valve dysfunction and no pseudoaneurysm of the aortic or coronary ostial suture lines has been detected. Only 1 patient (12.5%) needed prolonged postoperative inotropic support for low cardiac output. One patient could not tolerate sternal closure after repeat homograft root replacement for Staphylococcus epidermidis prosthetic valve endocarditis. He underwent delayed sternal closure 4 days later. Postoperative atrial tachyarrhythmias were present in 3 patients (37.5%) and ventricular arrhythmia requiring treatment was present in 1 patient (12.5%). Atrioventricular block requiring insertion of a permanent pacing system developed in 1 patient (12.5%). Postoperative pneumonia developed in 2 patients (25.0%), in 1 (12.5%) leading to tracheostomy. Two patients (25.0%) experienced renal insufficiency attributable to ischemic acute tubular necrosis. Although 1 patient required a course of hemodialysis, renal dysfunction resolved in both patients.

Bacterial endocarditis was seen in 2 patients, representing the only re-reoperations required in this study. One patient died of endocarditis, as described above, 16 months after composite valve graft root re-replacement for noninfected pseudoaneurysm. In the other patient, Staphylococcus aureus endocarditis of his aortic homograft developed nearly 3 years after repeat root replacement. Although bacterial endocarditis was the indication for his previous operation, it was believed that his current infection was attributable to continued intravenous drug use. He was treated with repeat homograft root replacement and has been without evidence of recurrent infection. All patients with composite mechanical valve grafts inserted received long-term anticoagulation with warfarin. Neither hemorrhage related to anticoagulant therapy nor any thromboembolic events have developed in these patients.

Current status
At the time of last follow-up, 1 of the surviving patients was in New York Heart Association functional class II, and the remainder were in class I.

	Comment

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It took an entire century beginning with the early efforts of Moore in 1864 until Wheat and colleagues [1] first reported successful replacement of the entire ascending aorta and aortic valve in continuity. The difficulties associated with treating diseases of the aortic root are further emphasized by the number of operative methods for composite graft replacement described since then, the most common of which being the Bentall [2], Cabrol [3], and coronary button (Carrel patch) [4, 5, 7, 8, 12], techniques. The introduction of homografts for root replacement has been particularly useful in the treatment of root infection. The subset of patients requiring repeat root replacement represents a particular challenge. Although the number of patients requiring this procedure in any one institution is small, this study shows that the operation may be accomplished with excellent early and medium-term results. There were no early deaths and no deaths in the patients in whom the operative indication was endocarditis, although this has been associated with increased mortality in other studies [6, 13]. There have been reports in the literature of series of aortic root replacements [6–8, 12] and a report by Sundt and associates [14] on reoperative valve operation after homograft root replacement, but there is little information specifically addressing the risk of repeat aortic root replacement. In the report by Sundt and associates [14], 9 patients required repeat homograft root replacement with no early deaths but late mortality for this group was not specified. Other reports of mortality pertain to valve operation after root replacement or vice versa, ranged between 13% and 40% [6, 15–20]. The 1 patient who died in our study presented to another institution with advanced root sepsis 16 months postoperatively, and may have had a better outcome with more prompt treatment by homograft root replacement. Although the incidence of associated in-hospital complications was relatively high, the absence of early mortality and one (12.5%) late death in our series compare favorably and demonstrate that root re-replacement can be undertaken with acceptable risk and operation should not be delayed given the appropriate clinical circumstances.

The coronary button technique was used in all of our operations and we encountered no coronary ostial complications, bleeding from suture lines, or false aneurysm formation. We find mobilization of the proximal coronary arteries possible in the majority of patients and reserve Cabrol repairs for rare situations. Although with the Cabrol technique there is no tension on the coronary anastomoses and all bleeding sites can be visualized, the limbs of the grafts to the coronary arteries tend to kink and the limb to the right coronary artery can occlude [7]. With the Bentall technique of side-to-side anastomoses of the coronary ostia, bleeding can be difficult to visualize leading to pseudoaneurysm formation at these sites [7, 8]. Theoretical disadvantages of the coronary button technique include the time required to mobilize the proximal coronaries and ostia, the risk of damage to these vessels, occlusion caused by tension, and the fact that this may not be feasible in cases of aortic dissection [8]. None of these problems were encountered in our study patients. We recommend using the coronary artery button technique for virtually all first time and repeat root replacements, which may minimize late technical complications like pseudoaneurysm. Regardless of which method of coronary artery attachment is used, the principles of obtaining meticulous hemostasis and elimination of tension at suture lines cannot be overemphasized. In addition, we do not wrap the aneurysm wall around the graft as this can lead to tension on anastomoses, bleeding complications, pseudoaneurysm formation at each of the different suture lines, and perigraft hematoma causing supravalvar aortic stenosis or impingement upon a prosthetic valve with aortic regurgitation [4, 7, 8, 11].

As recommended in other studies [6, 12, 21], homografts were implanted in cases of root infection and composite grafts used in the remainder. Successful management of patients with sepsis involving the aortic root may be accomplished following the principles outlined by Buckley and associates [10]: (1) medical therapy should not be pursued to the point that resistant infection or irreversible myocardial injury has occurred; (2) extensive excision of all infected tissue even if other defects, such as heart block, may result; and (3) the causative organism must be sensitive to some form of antibiotic therapy. Endocarditis developed postoperatively in 2 patients, although in 1 patient the initial operative indication was not for infection and in the other the cause was believed to be continued intravenous drug use. Therefore, adhering to these guidelines there were no cases of truly recurrent endocarditis. These 2 patients represent the only reoperations required.

We recommend femoral arterial cannulation in most patients because of the risks associated with redo sternotomy in these patients. In some instances, cardiopulmonary bypass was instituted before sternotomy or to facilitate lysis of mediastinal adhesions.

There most likely will be an increasing demand for aortic root re-replacement due to late degeneration of composite bioprosthetic valve grafts and aortic homografts inserted over the past two decades. Also, patients with composite mechanical valve grafts may require treatment for systemic emboli, complications of anticoagulation, and valve failure. With advances in surgical technique and postoperative care, the use of protease inhibitors, namely aminocaproic acid or aprotinin, and the expanded use of retrograde cardioplegia and homografts, the conditions under which repeat root replacement can be performed have improved. Although the postoperative morbidity may be relatively high, we conclude that aortic root re-replacement can be accomplished with low early and medium-term mortality, and therefore this life-saving option should be pursued aggressively given the appropriate clinical indications.

	Acknowledgments

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We acknowledge the assistance of Judith Jones for preparation of the manuscript.

	References

Top Abstract Introduction Material and methods Results Comment Acknowledgments References

 

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