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Ann Thorac Surg 2000;70:851-855
© 2000 The Society of Thoracic Surgeons

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Original articles: cardiovascular

Composite graft replacement of the aortic root after previous cardiac surgery: a 20-year experience

^a Cardiothoracic Surgical Unit, Royal Prince Alfred Hospital, Sydney, Australia

Address reprint requests to Dr Hughes, Cardiothoracic Surgical Unit, Royal Prince Alfred Hospital, Missenden Rd, Camperdown, 2050, Australia
e-mail: joanna{at}cts.rpa.cs.nsw.gov.au

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. An aging population and prolonged survival of patients after cardiac operations has meant that composite aortic root replacement after previous cardiac operation is being performed with increasing frequency.

Methods. From January 1979 to July 1999, 32 patients underwent "reoperative" composite replacement of the aortic root at our institution. Previous operations were 16 aortic valve replacement, 9 coronary artery bypass grafting, 5 repair aortic dissection, and 7 others. Indications for operation included ascending aortic aneurysm in 16 patients, ascending aortic dissections in 10 patients, and other in 6 patients.

Results. The unit elective mortality was 3 of 26 (11.5%). One surgeon’s elective mortality was 1 of 22 (4.6%). The unit emergent mortality was 6 of 6 (100%). There has been one late death. Morbidity was low.

Conclusions. Reoperative aortic root replacement is a technically demanding procedure, but expertise in the area achieves low elective mortality. Consideration should be given to aortic root replacement at the initial procedure. Close follow-up of postcardiac operation patients is necessary to proceed with elective aortic root replacement if indicated. Emergent presentation in the reoperative setting has a very poor prognosis.

	Introduction

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Aortic root replacement after previous cardiac operation is a technically demanding procedure. However, improved myocardial and cerebral protection, plateletpheresis, and surgical expertise can make elective aortic root replacement in this reoperative setting possible with a low morbidity and mortality.

In the collective experience of 294 aortic root replacements at Royal Prince Alfred Hospital from November 1970 to July 1999, 32 were performed in patients who had had previous cardiac operation. This experience of "reoperative aortic root replacement" in our unit has increased over time and the techniques modified to improve outcomes.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
Clinical considerations
Between January 1979 and July 1999, 32 patients underwent "reoperative aortic root replacement" at our institution. Valve-sparing procedures have been excluded from this series. The median age of the patients at reoperative aortic root replacement was 62 years (41 to 73). The median age at the initial procedure was 49 years (12 to 68) with a median of 11 years (6 days to 35 years) between procedures. Twenty-nine of the reoperative procedures were undertaken after 1990. Clinical considerations are summarized in Table 1. One patient with tetralogy of Fallot had had three previous sternotomies (Blalock shunt, repair tetralogy of Fallot, ventral septal defect repair). One patient had two previous aortic valve replacements (AVR). Five patients were noted to have a dilated or thin-walled ascending aorta at their initial procedure. One of the patients was noted to have a congenital bicuspid aortic valve.

Follow-up information was obtained on all patients. Patients or their referring cardiologist or local doctors were contacted by telephone or by mailed questionnaire.

Technique
Large bore central lines and a pulmonary artery catheter are used routinely. Transoesophageal echocardiography has been used intraoperatively since 1993, allowing assessment of the valves, left ventricle, and aortic pathology.

Since August 1994, plateletpheresis has been used routinely for patients having composite aortic root replacement [1]. Platelet-rich plasma is harvested after induction of anesthesia, before the commencement of the surgical procedure. The plasma is used to provide autologous platelet transfusion when the heparin is reversed and to make platelet gel for topical hemostasis immediately before sternal closure.

The proximity of the heart to the sternum is assessed on a lateral chest roentgenogram for all reoperative cardiac and all ascending aortic procedures. When in doubt, femoral cannulation and cardiopulmonary bypass can be commenced before the sternotomy. In any event, the femoral vessels are exposed (usually the right) or a guidewire is placed percutaneously.

Reoperative sternotomy is performed using an oscillating saw. The pericardial cavity is invariably obliterated by dense adhesions and careful sharp dissection is required to mobilize the front and right of the heart, facilitating cannulation. Cannulation is normally through the femoral artery and right atrium (two stage cannula) but femoro femoral or combinations of technique may be necessary. The aortic root is mobilized after bypass is established.

The patient is cooled to 25°C if no arch operation is contemplated. If total circulatory arrest is necessary then cooling is continued to 16° to 20°C. The left ventricle is vented through the right superior pulmonary vein and a coronary sinus cannula placed through the right atrium. The aorta is cross-clamped on fibrillation and the heart arrested with cold crystalloid cardioplegic solution usually delivered through the coronary sinus. Direct coronary instillation is used if there is delayed onset of cardioplegia or the myocardial temperature does not fall. Blood cardioplegic solution is delivered retrogradely or antegradely every 20 minutes. Topical cold saline is used to augment systemic hypothermia.

If the patient requires concomitant coronary artery bypass grafting (CABG), the distal anastamoses are performed before aortic root replacement and the proximal anastamoses performed at the end of the procedure. The ascending aorta is opened and the pathology and anatomy assessed. The entire aneurysm is excised. The coronary ostia are dissected from the native aorta as buttons with a large "tongue" of aorta left intact on the cephalad side, providing a safe site for retraction. Inferiorly, the aortic resection extends to the aortic annulus. The diseased valve is then excised and the annulus measured accurately. A collagen-impregnated Dacron composite valved conduit prosthesis is used in most cases. If the patient has had a previous aortic valve replacement, and it is functioning normally, it may be left in situ and a tube graft sewn to the sewing ring of the intact valve.

Teflon felt-pledgeted 2-0 Ticron horizontal mattress sutures are placed from the aortic annulus to the sewing ring of the valved conduit. Since August 1988, an interlocking suture technique has been used, that is, the first needle of each stitch passes through the preceding pledget. Usually the Teflon pledgets are placed outside the aortic annulus. The graft is then "parachuted" into position (Fig 1). Two carefully positioned side holes are then cut in the Dacron with an ophthalmic cautery (potentially toxic gases are aspirated with the discard suction) (Paul Peters, 1999, personal communication) and each coronary ostium anastomosed to the graft using a continuous 5-0 Prolene suture (Ethicon, Somerville, NJ). The distal aorta is then trimmed and reinforced with a Teflon felt "sandwich" inside and outside the wall (Fig 2). The graft is cut to length and the distal anastomosis completed with a continuous 3-0 Prolene suture, pulling the graft into the distal aorta (Fig 3). Variations in the coronary anastomosis technique are well known—saphenous vein interposition grafts, the Cabrol technique [2], or even conventional CABGs may be necessary if adhesions or a distorted heart make direct coronary anastomosis difficult. Two patients required aortocoronary ostial interposition grafts (1 Dacron, 1 saphenous vein), when adhesions made coronary mobilization unsafe.

View larger version (44K): [in this window] [in a new window]   Fig 1. Interlocking 2-0 Ticron Teflon-pledgeted sutures are placed from outside the aortic annulus to the sewing ring of the valved conduit and the graft "parachuted" into position.

View larger version (31K): [in this window] [in a new window]   Fig 2. After trimming, the distal aorta is reinforced with a Teflon felt "sandwich" inside and outside the wall and the distal anastomosis performed with 3-0 Prolene.

View larger version (38K): [in this window] [in a new window]   Fig 3. Completed aortic root replacement. Note the interlocking Teflon pledgets outside the aortic annulus, the distal anastomosis with the Teflon felt sandwich, and the coronary ostia anastomosis to the side of the graft.

Operative procedures and concomitant procedures are summarized in Table 2. A composite valved prosthesis was used in 26 patients (Medtronic Hall in 23 patients, Carbo-Medics in 2, and Bjork-Shiley in 1). One patient with gastrointestinal angiodysplasia, unable to take warfarin, had an aortic root homograft. One patient had a tube graft sewn to a Bjork-Shiley valve and 4 patients, with functioning previous aortic valve replacements, had a tube graft sewn to the sewing ring of the intact valve.

The median duration of cardiopulmonary bypass for the entire series was 213 minutes (118 to 480); the median duration of aortic cross-clamping was 128 minutes (78 to 210).

	Results

Top Abstract Introduction Material and methods Results Comment References

 
Mortality
Elective procedures were performed on 26 patients with a perioperative mortality of 11.5% (3 patients). However, 1 surgeon had performed most (22) of these surgical procedures, with a mortality of 4.6% (1 patient). The causes of perioperative deaths in the elective cases included a clotted valve in the first 24 hours, myocardial failure, and right ventricular failure after surgical injury during cardiac mobilization.

Six patients underwent an emergent procedure for acute dissection or ruptured aneurysm. Five patients presented to the unit in a moribund state with multisystem organ failure and 1 patient had an on-table dissection at repeat CABG. Perioperative mortality in this group was 100% (6 patients). In 4 cases the patients were unable to be weaned from bypass, whereas the other 2 patients died within the first 24 hours from myocardial failure and coagulopathy.

There has been one late death. The patient was discharged well after uneventful reoperative CABG and aortic root replacement. After developing a late sternal wound infection and progressive cardiac failure, the patient died 10 weeks postoperatively.

Data for a larger group (Paul Peters and colleagues, in preparation) of aortic root replacements with long term follow-up is available for patients operated on between November 1970 and December 1996. One hundred ninety-six patients had 197 procedures with a 30-day mortality of 13.7% (27 of 197).

Morbidity
Overall morbidity was low. One patient required reoperation for hemostasis. Ten patients required intensive care management for more than 48 hours. Six patients required inotropic agents for more than 24 hours. Five patients required ventilation for more than 24 hours. Three patients developed acute renal failure, none requiring dialysis. Two patients had a perioperative neurologic event (this compares with 15 of 197 [7.6%] in the larger series in preparation). One of these patients has residual cognitive impairment, but lives independently, whereas the other patient has a residual hemiparesis and is cared for in a nursing home. Two patients developed groin cannulation wound infections. One patient required a laparotomy and right hemicolectomy for a perforated cecum, 5 days postprocedure. Five patients developed atrial fibrillation requiring digoxin. Five patients developed self-limiting ventricular arrhythmias.

One patient developed a late sternal wound infection. Two patients required insertion of permanent pacemakers for complete heart block, both more than 6 months postoperatively. Two patients had acute myocardial infarcts, both more than 2 years postoperatively. Three patients required readmission for anticoagulant-induced hematuria. Two patients describe having difficulty with their memory. One patient had a late neurologic event, with no residual deficit. No patients have required further cardiac surgical procedures. There has been no prosthetic endocarditis and no prosthetic failures.

	Comment

Top Abstract Introduction Material and methods Results Comment References

 
Aortic root replacement with reimplantation of the coronary arteries as first described by Bentall and De Bono [3] has been modified but remains a successful technique for treating aneurysmal disease and dissection of the aortic root. Improved surgical techniques and perioperative management [4] has reduced the morbidity and mortality associated with this procedure.

Several researchers [4–6] have reported an increasing incidence of patients presenting for reoperation on the aortic root; this increased incidence has certainly been the experience in our unit. Of the 32 patients in this series, 29 patients had their procedure since 1990. The aging population and the increasing frequency of cardiac surgical procedures are clearly significant factors.

Five patients in this series were noted to have a dilated or thin-walled aorta at their initial AVR. Interestingly, 4 of these patients had their reoperative procedure more than 10 years after the initial AVR. However, 1 patient, whose initial AVR was performed at another institution, presented only 18 months later with a large aortic root aneurysm.

Two patients in this series had Marfan’s syndrome. Indications for aortic root replacement in the presence of Marfan’s syndrome are well documented. Gott and colleagues [7, 8] replaced the ascending aorta when severe aortic insufficiency or aortic dissection occurred or when its dimensions exceeded 5 to 6 cm. We have a similarly aggressive surgical policy. Patients without Marfan’s syndrome and an aortic root longer than 5 to 6 cm should be considered for aortic root replacement in the setting of aortic valve disease.

The surgical techniques described in this paper have evolved over time. Although the techniques described are standard, the pathologic variations in the reoperative setting require the surgeon to be ready to modify techniques when required. Experience in this area enables the surgeon to make a precise assessment of the aortic root before performing the repair.

We have used plateletpheresis routinely since August 1994. The long bypass time and the moderate-to-deep hypothermia required while performing this surgical procedure commonly result in thrombocytopenia or platelet dysfunction. Our techniques and the benefits of plateletpheresis have been detailed previously. This retrospective work analyzed all patients undergoing aortic root replacement with a composite graft between June 1993 and April 1995 (14 with plateletpheresis, 17 historical "controls," and 6 excluded patients). Fifty percent (7 of 14) of the patients receiving plateletpheresis did not require any homologous blood product, compared with only 12% (2 of 17) of the "control" group [1]. Two patients in this reoperative series required no homologous blood product support. Other authors have had similar success with plateletpheresis [9].

The 5 patients in this series who presented to our unit acutely and the patient who required an on-table emergent procedure died. With the exception of the latter patient, these emergent patients were invariably in multisystem organ failure and moribund. The emergent presentation of a patient with aneurysmal rupture or aortic dissection has a very poor prognosis.

With experience and development of expertise in aortic root replacement, surgeons can perform the procedure with relative safety in the elective setting. Our unit perioperative elective mortality of 11.5% (3 of 26 patients) was comparable with other larger series in the literature [4, 10]. Even in the reoperative setting, the 4.6% elective mortality for aortic root replacement for one surgeon approached that of a first-time aortic valve replacement [11, 12].

Reoperative composite aortic root replacement is a technically demanding procedure and in the emergent setting the mortality is extremely high. We recommend two strategies to prevent the emergent presentation of these moribund patients:

1. Assessment of the ascending aorta at the time of the initial procedure (particularly in the case of aortic valve surgery), with aortic root replacement performed if the aorta is 5 cm or greater in diameter.
   
2. If the patient has had previous cardiac operation and the ascending aorta is noted to be dilated, then close follow-up is required to perform an elective, planned procedure if the aortic root diameter reaches 5 cm.
   

In this series, the median time between the initial procedure and reoperation was 11 years (range 6 days to 35 years). This long time emphasizes the need for lifelong follow-up, a view shared by other researchers [4, 5].

The old carpenters’ adage of "measure twice, cut once" clearly has a place in aortic root surgery.

	References

Top Abstract Introduction Material and methods Results Comment References

 

1. Gibson J.L., Wajon P., Hughes C.F., Thrift B. Intraoperative plateletpheresis for replacement of the ascending aorta and aortic valve with a composite graft. Asia Pacific Heart J 1997;6:92-97.
2. Cabrol C., Pavie A., Gandjbahkhch I., et al. Complete replacement of the ascending aorta and reimplantation of the coronary arteries. New surgical approach. J Thorac Cardiovasc Surg 1981;81:309-315.[Abstract]
3. Bentall H., De Bono A. A technique for complete replacement of the ascending aorta. Thorax 1968;23:338-339.[Abstract/Free Full Text]
4. Dougenis D., Daily D.D., Kouchoukos N.T. Reoperations on the aortic root and ascending aorta. Ann Thorac Surg 1997;64:986-992.[Abstract/Free Full Text]
5. Crawford E.S., Crawford J.L., Safi H.J., Coselli J.S. Redo operations for recurrent aneurysmal disease of the ascending aorta and transverse arch. Ann Thorac Surg 1985;40:439-455.[Abstract/Free Full Text]
6. Lawrie G.M., Earle N., DeBakey M.E. Long term fate of the aortic root and aortic valve after ascending aneurysm surgery. Ann Surg 1993;217:711-720.[Medline]
7. Gott V.L., Pyeritz R.E., Cameron D.E., et al. Composite graft repair of Marfan aneurysm of the ascending aorta. Ann Thorac Surg 1991;52:38-45.[Abstract/Free Full Text]
8. Gott V.L., Cameron D.E., Reitz B.A., et al. Current diagnosis and prescription for the Marfan syndrome. J Card Surg 1994;9(Suppl):177-181.[Medline]
9. Svensson L.G., Jianping S., Nadolny E., Kimmel W.A. Prospective evaluation of minimal blood use for ascending aorta and aortic arch operations. Ann Thorac Surg 1995;59:1501-1508.[Abstract/Free Full Text]
10. Svensson L.G., Crawford E.S., Hess K.R., Coselli J.S., Safi H.J. Composite valve replacement of the proximal aorta. Ann Thorac Surg 1992;54:427-439.[Abstract/Free Full Text]
11. Craver J.M., William S., Jones E.L., Guyton R.A., Hatcher C.R. Predictors of mortality, complications, and length of stay in aortic valve replacement for aortic stenosis. Circulation 1988;78:I85-I90.
12. Christakis G.T., Weisel R.D., David T.E., Salerno T.A., Ivanov J. Predictors of operative survival after valve replacement. Circulation 1988;78:I25-I34.

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