Congenital valvular aortic stenosis

Congenital aortic stenosis can be situated at different levels: subvalvular, valvular and supravalvular. The topic of this paper is the surgical treatment of the valvular stenosis. Since this valvular stenosis can present in the setting of multilevel stenosis and/or hypoplasia of the left ventricular outflowtract it becomes obvious that surgical treatment can be complex and difficult and that we also will have to adress these “tunnel” obstructions.

The development of symptoms depend on the gradient, which has the tendency to increase over time. A conservative valvotomy will be the treatment of choice since replacement of the valve at a very young age is less optimal.

74 Patients underwent valvotomy at our institution between 1977 and 2004. The hospital mortality of this intervention was 17.8% (5/28) in infants under the age of one year and 4.3% (2/46) in patients older than one year.

An aortic valvotomy is a palliative operation with the only aim to postpone replacement to a patient of adult size. The residual gradient and the presence of valvular incompetence - because of the dysplastic nature of the valve - after valvotomy has tendency to increase over time. This implies that all patients wll present themselves over time for valve replacement. 85% Of the 74 patients, described above, were reoperated 23 years after their primairy valvototmy.

The mortality and longterm performance of balloon dilatation - another option for palliation -

In patients with an “adult” size anulus primary valve replacement was performed in 107 patients during the same time frame with one hospital death in this subgroup. Before June 1991 our preference for replacement was a mechanical valve, except for cases with endocarditis (10 homografts) or young female patients with a chikld wish (3 bioprostheses). A classical infracoronary valve replacement was done in 27 cases, whereas a root replacement was performed in 80 patients. Our indication for a root replacement are: the association of an aortic aneurysm, the presence of endocarditis and replacement of the diseased aortic valve by a pulmonary autograft (Ross operation).

After June 1991 our surgical treatment of choice in aortic valve replacement was a Ross operation in patients under the age of 35 years.The reasons for this change in sugical approach were: the growth capacity of the autograft¹, the excellent reported late results², the absence of thrombo-embolic (TE) complications and the resistance to endocarditis. We limit the use of the Ross operation to younger patients because of the high cumulative risk of TE phenomena and endocarditis in younger patients with mechanical valvar prostheses. Another reason for restricting the use of the Ross operation is the limited availability of homografts, which in our opinion are the golden standard for reconstruction of the right ventricular outflowtract.

102 patients underwent a Ross operation between June 1991 and December 2004. The mean age at operation was 18.8 years (range 0.3 to 37.3 years). The mean follow-up was 4.4 years and 94% complete. 31% Of the operations were redo- procedures. The preoperative diagnoses were: congenital aortic valve stenosis/regurgitation (79 patiuents), complex subvalvular stenosis (14 patients), outgrowth aortic prosthesis (5 patients) and bacterial endocarditis (4 patients).

An aortic root replacement was performed in all patients. The autograft was replaced by a homgraft in 87 patients and a Contegra conduit in 9 patients. A Ross-Konno operation³ (extended aortic root replacement) was done in 18 patients, where the aortic anulus and subvalvular uotflowtract was narrow (“tunnel” stenosis). After Februar 1995 the autograft anulus was supported with a pericardial strip to prevent anulus dilatation. The ascending aorta was always tailored to match exactly the diameter of distal autograft.

Non letal complications occurred in 7 patients: 2 patients were treated with a permanent pacemaker because of surgical AV block, one patient developed a septal infarction secondary to a transection of a maior septal artery during a Ross-Kono operation and 1 patients was transplanted after placement of a RVAD assist system because of massive RV infarction (mono coronary artery system). All these complications occurred early in our experience. Three other patients underwent additional surgery during the same admission: one mitral valve replacement (endocardial fibroelastosis), placement of an ECMO in a patient undergoing a rescue Ross procedure and one patient underwent a CABG because of kinking of the RCA.

One patient died one week after operation following heart trasplantation because of very severe autograft laekage.

Two other patients died late (at 1.3 and 1.4 years postoperatively) secondary to persisent chronic heart failure. The overall Kaplan Meier survival was 96.2% at 13 years.

Table 1 gives an overview of the performance of the auto- and homografts measured by echocardiography at the last follow-up.

Table 1 AUTOGRAFT HOMOGRAFT

n n

GRADIENT 0 - 10 93 26

(mmHg) 10 - 20 2 28

20 - 40 1 29

>40 - 8 °

LEAKAGE 0 - 1 73 83

(0-4) 1 - 2 18 8

2 - 3 4 * 2

>3 4 *

° 3 homografts replaced

* 6 autografts replaced

One autograft was replaced one ady after surgery because of a technical failure during implantation, five other patients because of progressive dilatation of the autograft and ascending aorta. These five patients were operated before Februar 1995. After this date all anular anatomoses of the autograft were supported with a strip of bovine or autologous pericardium. Nine other patients, all with tailored distal autograft anastomsis, developed autograft dilatation with stable and acceptable aortic regurgitation.

Five RVOT homografts were replaced at different intervals (0.2 month to 13.1 year): two because of endocarditis, two because of a combination of a progressive increase of the peak instantaneous gradient and compression by a dilated autograft, which was replaced during the same re-intervention.

The Kaplan Meier replacement-free incidence for autograft and homograft valves was 78+16% at 13 years.

We still favor valvotomy for the primary surgical approach for isolated simple congenital aortic stenosis. The future will prove whether interventional balloon dilatation will prove to be compettive. From our result we found no difference in terms of survival and interval between primary palliation and secondary valve replacement. Our experience however compares two historical series: the surgical series being the oldest. A more prospective approach is warranted.

The Ross operation is our operation of choice, especially in the younger patients. The autograft has proven to grow, is resistent to endocarditis and needs no anticoagulant treatment. Bioprostheses tend to degenerate very fast, especially in very young patients. Mechanical prostheses have still a considerable cumulative risk (0.5-1%/patient/year) of thrombo-embolic (TE) complications despite anticoagulant treatment. Self monitoring of anticoagulant treatment will probably decrease this risk. The risk of prosthetic endocarditis (+0.4%/patient/year) also is not negligible.

Our medium-term results of the Ross operation are good. The high incidence of root dilatation^4,5,6, when a root replacement has been done, is very concerning. From our result we have the impression that, in those cases where the autograft anulus was supported, the dilatation of the ascending aorta and/or the autograft root is responsible for the increasing incidence of “aortic” incompetence as time passes by.

Close follow-up will show wether the supported anulus will prevent late increase of aortic regurgitation.

The dilatation of the autograft per se seems not to be an indication for reoperation, as long as the diameter of the dilated autograft remains under 6 cm and does not compres the homograft in the RVOT.

The tailoring of the ascending aorta to the size of the autograft will probably not prevent subsequent dilatation. Partial replacement of the ascending aorta or reinforment of the autograft anastomosis with a tubular graft might be the solution of this problem^7,8.

With these consideration in mind we still favor the use of the Ross operation in young patients.

1. Raja SG, Pozzi M. Growth of pulmonary autograft after Ross operation in pediatric patients.

3. Daenen W , Gewillig M. Extended Aortic Root Replacement with Pulmonary Autografts

4. Elkins RC, Lane MM, McCue C, Chandrasekaran K. Ross operation and aneurysm or dilatation of the ascending aorta.

5. Hraska V, Krajci M, Haun Ch, Ntalakoura K, Razek V, Lacour-Gayet F, Weil J, Reichenspurner H. Ross and Ross-Konno procedure in children and adolescents: mid-term results.

6. Kouchoukos NT, Masetti P, Nickerson NJ, Castner CF, Shannon WD, Davila-Rom. The Ross procedure: long-term clinical and echocardiographic follow-up.

7. Leyh RG, Kofidis T, Hagl C, Fischer S, Knobloch K, Akhyari P, Karck M, Haverich. Ross procedure with combined replacement of the ascending aorta: on autograft root function and distentibility.

8. Luciani GB, Casali G, Favaro A, Prioli MA, Barozzi L, Santini F, Mazzucco A. Fate of the aortic root late after Ross operation.