Aortic Valve Repair: Does it Work?

In 1997 M. Antunes wrote an editorial comment entitled  - “Aortic valve repair: still a dream?” and in our last meeting in Vienna, the breakfast session was entitled “Aortic valve repair: does it work?”  If we look deeply into those titles, dream is changed for work. Is aortic repair working now? How well is it working? I’ll try to answer these questions following this approach:

• Lessons from the mitral repair
• From the mitral to the aortic repair
• Aortic valve repair:
  • Functional approach
  • Etiology, Clinical Pathology, TEE and Surgical Procedures
  • Surgical considerations and results
• Conclusions

Lessons from the mitral repair

Why mitral valve repair is working now and working very well?

It is mainly due to the genius work of the pioneers. Carpentier established the base of the mitral repair by his functional approach of the mitral regurgitation: (1) dysfunction, (2) lesion, and (3) surgical technique. Based on a better knowledge of the functional anatomy of the mitral valve and the patho-physiology of the mitral regurgitation, this functional approach allowed the famous classification of mitral dysfunctions (Types I, II and III), the description of responsible lesion(s) and consequently, the search of the most appropriate surgical techniques. The aim of repair is to restore the function rather than the anatomy. Mitral repair can now succeed if we identify all dysfunction(s), all responsible lesion(s) and apply the appropriate technique(s).

Another lesson learned from the mitral repair is related to the repair durability. It depends on the degree of immediate success (residual MR and prognosis), on the quality of tissue left behind surgery (rheumatic versus degenerative), and mostly on the concept of the repair stabilization (ring annuloplasty and coaptation area).

From the mitral to the aortic valve repair
                                                              
Are the two major lessons learned in mitral repair (functional approach and repair stabilization) useful in aortic valve repair?

The functional approach is based on a better understanding of the anatomy of the aortic valve and the patho-physiology of the aortic regurgitation.

Functional anatomy:  Because of increasing experience in aortic valve sparing surgery, and with the stentless aortic valve (xenograft, autograft and homograft), the aortic valve is now considered not only valve cusps, but a functional unit comprising the aortic annulus, the cusps, the Valsalva sinuses, the commissures, and the sino-tubular junction. We now recognize that the function of the aortic valve depends on the integrity of this functional unit.

Patho-physiology of the aortic regurgitation: Aortic regurgitation may be secondary to a pathology of the aortic wall (aneurysm or dissection) or the cusps (prolapse, perforation, bicuspid valve or cusp retraction).

Techniques of aortic valve repair and reconstruction of the aortic root have been advocated by some dedicated surgical groups with acceptable long term results, but more widespread adoption has been hampered by a lack of a clear and simple description of the famous concept: dysfunction – lesion - surgical techniques, and its systematic application in any kind of aortic regurgitation. Because the difficulty in aortic valve repair is the recognition of the exact lesions responsible for the insufficiency and the selection of the adequate operative maneuvers, a functional classification of aortic root and valve abnormalities responsible for aortic insufficiency has been developed which in many ways is similar to that proposed by Carpentier with regard to the mitral valve.

Aortic valve repair

Functional approach:
  
The aortic root with its components is considered as a functional unit, its two borders the inner (aorto-ventricular junction) and the outer (sino-tubular junction) are considered  “the functional aortic annulus” (FAA) (equivalent to the mitral annulus).

Type I.   Normal appearing cusps with FAA dilation.
             Ia:  Distal ascending aorta dilation (sino-tubular junction)
             Ib:  Proximal (Valsalva sinuses) and sino-tubular junction dilation
             Ic:  Isolated FAA dilation
             Id:  Cusp perforation and FAA dilation
Type II.  Cusp prolapse: excess of cuspal tissue or commissural disruption
Type III. Cusp retraction and thickening

Note that the FAA is always present in the case of aortic regurgitation no matter what the responsible lesion is.  Thus, functional annuloplasty is necessary in any valve repair for aortic regurgitation. In addition, many lesions could contribute to the genesis of the dysfunction; namely, valve regurgitation.  Accordingly, all lesions need correction to achieve correction of the dysfunction.

Etiology, clinical pathology,TEE and surgical procedures:

Type Ia: Atherosclerotic etiology. It is characterized by progressive dilation of distal ascending aorta in the area of the sino-tubular junction; often associated with arch pathology. At TEE, the root looks normal with sino-tubular junction dilation, the aortic regurgitation (AR) jet, when present, is perpendicular to intraventricular outflow tract. The appropriate surgical technique is sino-tubular junction remodeling or replacement of the ascending aorta with a Dacron tube graft. The appropriate diameter is equal or less than the aorto-ventricular diameter. When AR is present, with the same jet direction, a sub-commissural annuloplasty is systematically added (FAA, TYPE I).

Type Ib:  Characteristic of degenerative diseases of the media, Marfan syndrome and connective tissue disorders (Valsalva sinuses dilatation): AR appears when sino-tubular junction is dilated and then it induces to aorto-ventricular dilatation (FAA dilatation). When AR is severe, an additional cusp prolapse must be suspected. The TEE shows enlargement of the root with a jet perpendicular to intraventricular outflow tract, in case of absence of prolapse; and eccentric in case of prolapse; in some patient there is a severe aorto-ventricular junction dilatation (annulo-aortic ectasia) associated.

The surgical techniques for Type Ib depend on the responsible lesions:

• Yacoub operation most indicated in case of absence of AR
• David operation in case of AR without prolapse
• Repair of the cusp prolapse and David operation in case of additional prolapse

Type Ic: This type is present whenever there is AR and is then present in all three types. Isolated is a concomitant finding in patients operated for valve repair or CABG.  The TEE shows the absence of any prolapse, any aneurysmal dilatation and the jet is perpendicular to the intraventricular outflow tract, a subcommissural annuloplasty and sino-tubular junction plasty can eliminate the aortic regurgitation.

Type Id:  Cusp perforation traumatic or mainly due to infective process. Due to the AR, there is FAA dilatation, and the surgery must combined patch repair and FAA plasty.

Type II:  Cusp prolapse may be idiopathic and associated to HTA; usually one or two cusps (NC - RC), and rarely the three cusps are prolapsed. It can be also present in type Ib (late in the evolution) and Type Ia. It is the major finding in regurgitant bicuspid valve. Acute aortic dissection with commissural disruption is associated with Type II lesions. It can be surgically induced: stentless valve implantation (mainly in subcoronary implantation) and valve sparing surgery. The TEE shows an eccentric jet towards the septum or toward the mitral valve. Free margin plication or triangular resection is the main surgical technique to repair the valve prolapse; we favor plication.

Type III:  Arantius nodule hypertrophy with lack of central coaptation, rheumatic valve with cusp retraction, calcification of the cusp with impaired motion. AR jet is central. The selected surgical techniques are: shaving of the nodes and free margin, cusp extension with pericardium, calcium enucleation.

Surgical considerations and results

The systematic approach of patients with pure aortic regurgitation, aiming to identify all lesions responsible for aortic regurgitation may help the surgeon in the selection of the appropriate surgical technique(s) needed to correct the aortic regurgitation.

This classification and the detection of lesions are made possible by experienced echocardiographists, pre and preoperatively. In this evolving evaluation a meticulous and careful surgical inspection of the aortic root and aortic valve may add some validation of the echocardiography findings and also discover other lesions missed at the echo evaluation. At our department we have been using, for many years, this functional approach of aortic regurgitation; it allows us to identify patients for aortic valve repair or sparing operation. All patients with pure aortic regurgitation are now considered for conservative surgery with excellent rate of feasibility and predictability.

We still have about 15% of patients who need perioperatively a second run pump because of unacceptable residual aortic regurgitation; this residual AR may be due to a missed, untreated lesion or to a new induced lesion related to surgery. To recognize these lesions and treat them extends the feasibility of conservative surgery.

Conclusions:

1. This approach may help cardiologists and surgeons to use the same language, and consequently, the possibility to compare patients, and the results of surgery.
2. The most important concept is the functional aortic annuloplasty. Whenever we have aortic regurgitation, a common finding is the sino-tubular junction and aorto-ventricular junction dilatation, so when we perform aortic valve repair, FAA is mandatory.
3. This functional approach is an evolving concept and needs more validations and corroboration. I do believe that like mitral valve repair, aortic valve repair could work very well if we understand aortic valve physiopathology, if we detect the lesions, and we perform the appropriate surgical technique(s).

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