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Eur J Cardiothorac Surg 2002;21:1049-1054
© 2002 Elsevier Science NL

Anatomical mismatch of the pulmonary autograft in the aortic root may be the cause of early aortic insufficiency after the Ross procedure

^a Department of Cardiothoracic Surgery, Sahlgrenska University Hospital, Göteborg, Sweden
^b Department of Clinical Physiology, Sahlgrenska University Hospital, Göteborg, Sweden

Received 18 September 2001; received in revised form 13 February 2002; accepted 19 February 2002.

* Corresponding author. Fax: +46-31-41-79-91
e-mail: gunnar.svensson{at}medfak.gu.se

	Abstract

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 
Objective: Early aortic insufficiency can be a problem after the Ross procedure. Anatomical mismatch and an inexact surgical technique may lead to distortion of the normal pulmonary valve geometry and subsequent incorrect leaflet coaptation and valve insufficiency. In this study, we assessed the efficacy of changing and improving the surgical technique to minimize the early pulmonary autograft valve failure. The modifications and the strategy are discussed. Methods: From January 1995 to February 1999, a total of 77 adults underwent the Ross procedure for aortic valve replacement at Sahlgrenska University Hospital. The operative technique used was full free-standing aortic root replacement with a pulmonary autograft in all cases. In the first 24 cases, the diameter of the pulmonary roots was seldom measured, eye-balling was used to exclude anatomical mismatch due to a dilated aortic root, and only one attempt of correction was made, which failed. In the other 53 cases, the technique was improved by: (1) reducing the aortic anulus diameter in cases with moderate dilatation; (2) excluding cases with severe dilatation of the aortic annulus; (3) adjusting the diameter of the sinotubular junction of the aorta to the diameter of the sinotubular junction of the pulmonary artery; (4). reimplanting the left ostium in the autograft, and (5) changing the proximal anastomosis technique. Results: In this study, we had an early aortic incompetence of grade 2 in eight patients among the first 24 patients. In the other 53 patients, postoperative echocardiography at 1 week revealed aortic insufficiency of grade 2 in two patients. Conclusions: Aortic insufficiency after the Ross procedure can be minimized by patient selection, intraoperative correction of anatomical mismatch and improved surgical technique.

Key Words: Aortic valve • Pulmonary autograft replacement • Ross procedure • Aortoplasty • Anuloplasty • Autograft insufficiency

	1. Introduction

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 
Pulmonary autograft replacement of the aortic valve was introduced by Sir Donald Ross in 1967 [1]. After the reports of excellent long-term results after the Ross procedure, we have extended the indication for total aortic root replacement with an autograft to adults [2]. The clear advantages for adults include absence of anticoagulation therapy, thromboembolism and audible valve closure (click sound). Other advantages are a low transvalvular gradient, high resistance to endocarditis and superior long-term durability among biological valve replacements in the aortic position [3].

There are drawbacks, however, one being the complexity of the surgical procedure, which is demanding on the surgeon's skills and often leads to a learning curve affecting the results.

At Sahlgrenska University Hospital, we have used the Ross procedure in adults for aortic valve replacement. In the first 24 patients, postoperative echocardiography at 1 week revealed aortic insufficiency grade 2 in eight patients. Although this did not necessitate surgical intervention, it is still of concern because of the risk of progressive dilatation with time, and it is an unacceptable result with a procedure for which a safer alternative exists.

In this study, we assessed the efficacy of improving surgical technique and adjusting anatomical mismatch by changing the strategy for minimizing the early autograft valve failure. The modifications and the strategy are discussed.

	2. Materials and methods

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 
2.1. Patients
A total of 77 patients underwent the Ross procedure at Sahlgrenska University Hospital, Göteborg, Sweden between January 1995 and February 1999. The mean age was 44 years (range 17–66 years). All patients had a preoperative transthoracic echocardiography (TTE). Pulmonary autograft replacement of the aortic valve was used only in patients with no or trivial pulmonary valve regurgitation in the preoperative evaluation.

Thirty-six patients presented with aortic stenosis, 23 with incompetence and 18 with combined defects. In 28 patients, there was a bicuspid aortic valve (six in the first 24 cases and 22 in the other 53 patients), in one patient a tetracuspid valve, in one patient unknown, and in 42 patients a tricuspid valve. Five patients had had previous aortic valve replacement. Three patients had undergone aortic prosthesis replacement due to porcine valve dysfunction. One patient had a replacement of a homograft due to a ruptured cusp. Three patients had endocarditis; of these one had an aortic mechanical valve with endocarditis and paravalvular leakage, one a previous commisurotomy, and one had to undergo immediate surgery because his condition was acute. Previous commisurotomy had been performed in nine cases. Patient characteristics are shown in Table 1.

2.5. Measurements
The diameter of the pulmonary root is best measured by intraoperative transeosophagal echocardiography (TEE) at the sinotubular junction (the ridge immediately above the commisures). The pulmonary valve is calculated to be 10–15% larger, as described by David [4]. The diameter of the aortic root was measured by TTE at the level of the anulus and the sinotubular junction. Intraoperatively, when the aortic valve was excised, the measurement of the aortic anulus was confirmed with valve sizers.

2.6. Modifications
In the latest 53 cases, the technique was improved by the following methods:

1. Reducing the aortic anulus diameter in cases with moderate dilatation.
   If the calculated diameter of the pulmonary anulus was similar to or larger than the aortic anulus measured with valve sizers, the pulmonary root was implanted without correction of the aortic anulus. If the diameter of the aortic anulus was larger than the diameter of the pulmonary anulus, reduction of the anulus was performed. The diameter was reduced by reducing the circumference according to the following formula: circumference=diameterx3.14. For example, a difference in one valve size, that is 2 mm, necessitates a circumference reduction of 6.5 mm. A strip of Teflon (PTFE-felt, Meadox) about 5 mm wide was used to reduce the circumference in the area between the two fibrous trigones where dilatation occurs. The Teflon strip was placed outside the aortic root in a subanular position at the same level as the autograft implant. The strip of Teflon was attached with a mattress suture at each end and the circumference of the anulus was reduced as required. The Teflon strip was then attached to the outflow tract by plicating the subanular region against the teflon strip using the mattress sutures as continuous sutures from each side and meeting in the middle (Fig. 1 .). After the anuloplasty was completed, the anulus was measured with valve sizers and the diameter checked. This Teflon strip can also be used to prevent later dilatation. The number of anuloplasties performed is shown in Table 4, and the anulus diameter before and after anuloplasty compared to the calculated autograft diameter is presented in Table 5.
   
2. Excluding cases with severe dilatation of the aortic annulus.
   If the aortic anulus measured with valve sizers differed by more than two valve sizers compared to the calculated diameter of the pulmonary anulus, the procedure was not performed. We feel that a reduction of more than 12–13 mm is inadvisable for safety reasons.
   
3. Adjusting the diameter of the sinotubular junction of the aorta to the diameter of the sinotubular junction of the pulmonary artery.
   If the diameter of the aorta at the level of the sinotubular junction corresponded to the diameter of the pulmonary sinotubular junction, the distal anastomosis was performed. If the diameter of the aorta was larger than the diameter of the pulmonary sinotubular junction, the aorta was reduced. The reduction was performed with an aortoplasty in which the aortic wall was duplicated and sutured and reinforced with a Teflon strip at each side. After the aortoplasty was completed, the aorta was measured with valve sizers and the diameter confirmed (Fig. 2 .). If there was not only a mismatch but also an aneurysm of the aorta, the ascending aorta was removed and a homograft of a size corresponding to the sinotubular junction of the autograft was used as an interponate. The number of aortoplasties performed is shown in Table 4.
   
4. Reimplanting the left ostium in the autograft.
   The technique was changed and the left ostium was excised from the aortic wall and reimplanted in the autograft (Fig. 3 ). The distal anastomosis technique was changed from one continuous suture line to three continuous 4:0 polypropylene (Prolene^©) suture lines. Care was taken to divide the circumference of the autograft and the circumference of the ascending aorta into three equal parts, anastomosing each part of the autograft to a corresponding part of the aorta with one continuous suture line. In this way, the risk of mismatch and malpositioning was minimized.
   
5. Changing the proximal anastomosis technique.
   To simplify spacing, the autograft was not inverted and the proximal anastomosis was performed with interrupted sutures (30-40) placed in a subanular horizontal line corresponding to the horizontal proximal end of the autograft (Fig. 3). The mid-cusp points in the aortic anulus were defined with a Toronto^© valve sizer, which is marked at each 120°, dividing the circumference into three equal parts. These points were marked with three sutures to serve as guides. The corresponding points in the autograft were also marked. The suture material used was 4:0 silicon-treated braided polyester (Ti-Cron^©, Davis and Geck). We use blue and white sutures alternately to simplify identification of corresponding suture ends.
   

View larger version (78K): [in this window] [in a new window]   Fig. 1. Anuloplasty.

View larger version (22K): [in this window] [in a new window]   Fig. 2. Checking the diameter after aortoplasty.

View larger version (26K): [in this window] [in a new window]   Fig. 3. The left ostium dissected from the aortic wall and proximal anastomosis with interrupted sutures.

The assessment of aortic insufficiency severity was based on a number of variables: color Doppler jet characteristics including jet width and area, continuous wave Doppler intensity and shape of the spectral recording, left ventricular dimensions and pulmonary artery pressure [5,6]. These variables are either directly influenced by aortic insufficiency severity or related to compensatory changes in the heart. All patients were graded on a four-point scale. Grades 3 and 4 indicate severe insufficiency.

2.8. Statistical analysis
Categorical data are given as total numbers; continuous variables are given as mean±SD. Differences between groups were assessed by the two-tailed Student's t-test for independent variables, and significance assumed for P-values less than 0.05.

	3. Results

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 
The early mortality (30 days) for the whole group was three patients (4%). One patient with a previous commisurotomy presenting with a combined defect and a left ventricular ejection fraction of 30% had an extensive myocardial infarction. He received a left ventricular assist device (LVAD), but did not recover and died of multiorgan failure on day 7. The second patient had an uneventful operation and died after discharge; the autopsy showed no abnormality. The third patient had a postoperative episode of hypertension during transport to the ICU and subsequent massive bleeding necessiting reexploration. A proximal autograft suture line rupture was successfully repaired but resulted in right ventricular failure. This patient was treated with an intra-aortic balloon pump (IABP) and right ventricular assist device (RVAD) but the myocardial function was not restored. On day 17, he received a transplant but unfortunately developed biventricular donor heart failure and died.

In the first 24 cases, early postoperative complication was bleeding, necessitating reoperation in four patients (16%): in one patient from the distal anastomosis of the autograft, in one from the back wall of the vena cava superior, and in two due to tamponade where no obvious source of bleeding was found. In the other 53 patients, reoperation for bleeding was required in four patients (7.5%): in one patient from the right outflow tract, in one patient from a partial rupture of the proximal suture line due to postoperative hypertension, which was successfully repaired, and in two patients in whom no obvious source of bleeding was found.

Other early postoperative complications included transient cerebral ischemic attacks due to postoperative fibrillation in one patient and pacemaker insertion in one patient. Four patients had perioperative myocardial infarction. Two patients had a fatal myocardial infarction and are included in the early mortality figure. Two patients had a non-fatal myocardial infarction. A 40-year-old woman had postoperative electrocardiographic evidence of myocardial ischemia suspected with TTE and confirmed with postoperative coronary angiography, which showed a proximal LAD stenosis (this patient had not had a preoperative coronary angiography). The patient was reoperated on and underwent a bypass with a left internal mammery artery to the LAD. This patient did well. The other patient was weaned from cardiopulmonary bypass and developed right ventricular failure. When disturbance of the right coronary artery was suspected, a coronary bypass with a saphenous vein graft to the right coronary artery was performed. This patient also did well.

Two patients with no autograft insufficiency after the procedure required additional sutures to achieve hemostasis: in one patient in the proximal autograft anastomosis and in the other in the left coronary anastomosis. Unfortunately, these extra sutures caused aortic insufficiency, in the first patient probably by causing anatomical mismatch and in the latter by grasping the left coronary cusp. An option, at this point, was replacement with an aortic valve homograft, but the surgeon was uncertain of the additional time for thawing a frozen homograft and whether prolonging the aortic cross clamping time might influence the outcome. These patients were converted to mechanical composite grafts and did well.

In the first 24 patients, postoperative echocardiography at 1 week revealed grade 2 insufficiency in eight patients (33%). Five were tricuspid and four out of these were dilated (28, 30, 31 and 38 mm) and one was normal (27 mm). Three were bicuspid and one of these was dilated (32 mm) and two were normal (20 and 24 mm). In the other 53 consecutive patients, postoperative echocardiography at 1 week revealed grade 2 insufficiency in two patients (4%). One of these was bicuspid and the other tricuspid. Both these valves had normal dimensions (24 and 22 mm). The echocardiographic results are shown in Table 6.

	4. Discussion

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 
The most common technique used for aortic valve replacement with the pulmonary autograft is free-standing root replacement [7–9]. The free-standing root technique preserves the anatomical unit of the pulmonary root and may reduce the potential risk of incorrect anatomical positioning. In spite of this, early aortic incompetence and reoperation after the Ross procedure have been reported by several groups [8,10]. In this study, we had an unacceptable early incompetence in the first 24 patients.

The key to achieving sufficiency of the autograft is an understanding of its anatomical relations. We felt that anatomical mismatch and an incorrect surgical technique may lead to distortion of the normal pulmonary valve geometry and subsequent incorrect leaflet coaptation and valve insufficiency. This problem can occur both at the level of the proximal and the distal anastomosis.

If the autograft anulus dilates due to size mismatch, the leaflet attachments are pulled laterally, causing central leakage. If the pulmonary sinotubular junction dilates due to size mismatch between a smaller pulmonary sinotubular junction and a larger aortic sinotubular junction, the commisures in the autograft are pulled out, leading to defective coaptation and central leakage. An incorrect proximal and/or distal anastomosis technique may also lead to distortion of the pulmonary valve geometry and lead to incorrect leaflet coaptation and subsequent leakage.

In the first 24 patients, a preoperative TTE was performed in all cases. Of the eight patients that developed early grade 2 aortic insufficiency, only three were evaluated as having a normal aortic anulus diameter (20, 24 and 27 mm), and five were dilated (28, 30, 31, 32 and 38 mm). This experience indicated that anatomical mismatch of the pulmonary and aortic anulus may contribute to aortic valve insufficiency.

Even with a normal aortic anulus diameter and a competent pulmonary valve on preoperative TTE, early aortic insufficiency developed. This was interpreted as being due to a technical error during implantation of the autograft.

In this study, we have modified the strategy according to two main principles; one is correction of anatomical mismatch and the other is optimizing the surgical technique, to achieve less aortic insufficiency.

Correction for autograft to aortic anulus and aortic sinotubular junction mismatch requires reproducible and reliable measurements. Because of the difficulty in measuring the pulmonary valve anulus correctly by transthoracic or transoesophageal echocardiography, due to technical errors, these measurements were not used in this study. We have chosen to measure the pulmonary sinotubular junction by intraoperative TEE and to calculate the pulmonary valve anulus [4]. Assessing the sinotubular junction and/or the anulus of the pulmonary root with valve sizers was not used in this study, due to the risk of overdistension.

The reason for excluding cases with severe dilatation of the aortic anulus is that it is more difficult to perform a reduction in these cases, with a higher risk of technical errors. Furthermore, there is a risk that these cases with severe dilatation have a disorder involving the connective tissue, which could lead to progressive dilatation.

The Teflon strip was used not only to reduce the diameter but also to prevent later dilatation. One could argue that this precaution could be taken in cases with severe dilatation after a reduction, but with the experience of having an unacceptable rate of grade 2 early incompetence we adopted a cautious attitude.

To perform the proximal anastomosis with interrupted sutures is more time-consuming, but in our experience worthwhile because it simplifies spacing and reduces the risk of distorting of the normal pulmonary valve geometry. At first, polypropylene sutures were used. Due to the stiffness of this material, it was difficult to keep all sutures in order after the sutures were placed and before they were tied one-by-one. We therefore changed to 4:0 silicon-treated braided polyester. This suture material is smooth and easy to handle.

Retention of the left ostium with a tongue of the aortic wall reduces the risk of kinking of the left coronary artery and eliminates the need for one coronary anastomosis. This technique really implies that the autograft should have a corresponding notch if the distal anastomosis is to be performed without risk of distortion. The technique was changed and the left ostium was dissected from the aortic wall and reimplanted in the autograft. The autograft was given a straight rather than an undulating finish, facilitating anastomosis and safer recreation of the sinotubular junction.

In almost half of our patients (25 out of 53) the aortic root (the aortic anulus and/or the ascending aorta) required modifications to match the autograft. Other investigators have also recommended anuloplasty for correction of aortic anulus dilatation and reduction of larger aortic sinotubular junctions compared to the autograft, and we fully agree [4,10,11].

One must bear in mind that only by focusing on the problem of early autograft incompetence can we achieve an improvement, and the improvement may only reflect the surgeon's learning curve for this procedure. Despite this, we feel that changing the strategy has been beneficial to our results.

	5. Conclusion

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 
Early aortic insufficiency after the Ross procedure can be minimized by patient selection, intraoperative correction of anatomical mismatch and an improved surgical technique.

	Footnotes

 
Presented at the joint 15th Annual Meeting of the European Association for Cardio-thoracic Surgery and the 9th Annual Meeting of the European Society of Thoracic Surgeons, Lisbon, Portugal, September 16–19, 2001.

	References

Top Abstract 1. Introduction 2. Materials and methods 3. Results 4. Discussion 5. Conclusion References

 

1. Ross D.N. Replacement of aortic and mitral valves with a pulmonary autograft. Lancet 1967;2:956-958.[Medline]
2. Ross D., Jackson M., Davies J. Pulmonary autograft aortic valve replacement: long-term results. J Card Surg 1991;6(4 Suppl):529-533.[Medline]
3. Chambers J., Somerville J., Stone S., Ross D.N. Pulmonary autograft procedure for aortic valve disease: long-term results of the Pioneer Series. Circulation 1997;96:2206-2214.[Abstract/Free Full Text]
4. David T.E., Omran A., Webb G., Rakowski H., Armstrong S., Sun Z. Geometric mismatch of the aortic and pulmonary roots causes aortic insufficiency after the Ross procedure. J Thorac Cardiovasc Surg 1996;112(5):1231-1237.[Abstract/Free Full Text]
5. Perry G.J., Helmcke F., Nanda N.C., Byard C., Soto B. Evaluation of aortic insufficiency by Doppler color flow mapping. J Am Coll Cardiol 1987;9:952-959.[Abstract]
6. Hatle L., Angelsen B. Doppler ultrasound in cardiology. Philadelphia, PA: Lea & Febinger, 1985.
7. Elkins R.C. The Ross operation: a 12-year experience. Ann Thorac Surg 1999;68(3 Suppl):S14-S18.
8. Bohm J.O., Botha C.A., Rein J.G., Roser D. Technical evolution of the Ross operation: midterm results in 186 patients. Ann Thorac Surg 2001;71(5 Suppl):S340-S343.[Abstract/Free Full Text]
9. Schmidtke C., Bechtel J.F., Hueppe M., Noetzold A., Sievers H.H. Size and distensibility of the aortic root and aortic valve function after different techniques of the Ross procedure. J Thorac Cardiovasc Surg 2000;119(5):990-997.[Abstract/Free Full Text]
10. Elkins R.C., Knott-Craig C.J., Howell C.E. Pulmonary autografts in patients with aortic annulus dysplasia. Ann Thorac Surg 1996;61(4):1141-1145.[Abstract/Free Full Text]
11. Klena J.W., Shweiki E., Mahaffey H.W., Woods E.L., Benoit C.H., Gilbert C.L. Annuloplasty and aortoplasty as modifications of the Ross procedure for the correction of geometric mismatch. J Heart Valve Dis 2000;9(2):195-199.[Medline]

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