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Editorial comment

Department of Cardiac Surgery, Brussels University Hospital St. Luc, Brussels B-1120, Belgium

^_* Corresponding author. (Email: elkhoury{at}chir.ucl.ac.be).

	1. Introduction

Top 1. Introduction 2. Pathophysiology and mechanism... 3. Functional classification 4. Choice of the... References

 
Aortic repair surgery has gained a wider interest in the last 15 years; several publications showing short- and long-term results support this trend. A brief analysis of indications and aetiology can give us an idea as to which forms of aortic regurgitation are amenable to successful repair. Originally, aortic repair was only performed in case of rheumatic or calcific aortic regurgitation, which explains the poor results.

Because of the near disappearance of rheumatic disease in younger patients, other congenital and/or degenerative aetiologies have become more frequent indications for conservative aortic surgery. Thus, bicuspid aortic valve, degenerative diseases of the media (as Marfan syndrome), degenerative cusp prolapse and acute aortic dissection are nowadays the most common mechanisms of aortic insufficiency that can lead to conservative aortic surgery. Atherosclerotic aortic aneurysm of ascending aorta is another indication in elderly patients. Endocarditis of the aortic valve, acute or chronic, is a less favourable indication, contrary to what happens in the mitral valve. One common characteristic of the indications previously enlisted is the good quality of valvular tissue.

Although several surgical techniques have been published for treating different aortic lesions, it is rather impossible to draw any valid conclusions regarding the feasibility of aortic repair or the choice of the most appropriate technique. Actually in literature we still need a complete review of surgical results, with an overall analysis of recurrences and surgical failures. We do have to change our approach for a better understanding of this disease. How?

First of all we have to define the aetiologic and pathogenic mechanisms of aortic regurgitation, to propose a complete classification based on these mechanisms, and to describe several appropriate surgical techniques. This classification should have aetiologic, clinical and echocardiographic corroborations.

It is wise to take advantage from the experience of the mitral repair to propose a functional and global approach to the problem of aortic regurgitation. The major contribution of Carpentier in mitral surgery is his functional approach; to restore the function rather than the anatomy. This has changed the history of mitral surgery and his worldwide expansion.

Carpentier has defined the pathophysiology of mitral regurgitation; he established a classification, described the basis of a surgical correction directly corresponding to any dysfunction of the valve. Even more he defined a common language in mitral surgery. Finally he showed that mitral repair can only be successful if we identify all dysfunction(s), all responsible lesion(s) and apply the appropriate technique(s). Can we nowadays transfer the gifts of the mitral experience to the aortic valve?

	2. Pathophysiology and mechanism of the aortic regurgitation

Top 1. Introduction 2. Pathophysiology and mechanism... 3. Functional classification 4. Choice of the... References

 
The difficulty in aortic repair is the recognition of the exact lesions responsible for the insufficiency and the selection of the adequate operative manoeuvres to correct these abnormalities.

It is only in recent years that the aortic root complex has been recognized to act as an individual haemodynamic system that maintains aortic valve competence. The aortic root may be defined as the portion of the aorta that supports the leaflets of the aortic valve. 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). It comprises the sinuses, the leaflets, the commissures and the interleaflet triangles. We clearly understand that the valve regurgitation may be due to a dysfunction of the FFA or the leaflets.

	3. Functional classification

Top 1. Introduction 2. Pathophysiology and mechanism... 3. Functional classification 4. Choice of the... References

 
Understanding the pathophysiology of aortic regurgitation helps to develop a classification that starts from these mechanisms and includes the practical and empirical issues given by direct surgical examination. With our actual level of experience in aortic surgery we know that there is a close relation and interaction between the aortic root and the aortic valve. Aortic sparing surgery performs like an annuloplasty on the aortic valve. In other words it influences the configuration of the aortic cusps, sometimes creating a new prolapse and a residual regurgitation. It is well known that identification and management of cusp prolapse are the key to success in all aortic sparing operations. Moreover, the valvular prolapse can be isolated (normal aortic root), related to a diseased root or caused by a surgical act like subcoronary implantation of a stentless bioprosthesis or a Ross procedure.

It looks logical and useful to build up the classification on the two essential elements in the pathophysiology of the aortic regurgitation: the functional aortic annulus (FFA) dilatation and pathology of the leaflets. This functional classification can be obtained combining the data of the preoperative transesophageal echocardiography and the visual examination of the aortic root.

Type I. Normal appearing cusps (FAA dilation),

Ia: distal ascending aorta dilation (STJ dilatation),

Ib: proximal (Valsalva sinuses) dilatation and STJ 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.

This classification is the result of a clinical and aetiological analysis, where in type I there is a further sub-classification that includes all the possible pathology of the aortic root and ascending aorta, in type II all the valvular prolapse and in type III the effects of degenerative fibrotic diseases (rheumatic/calcific).

The evidence in favour of this classification is outstanding: a common language within surgeons, a systematic pathological assessment and moreover the choice of the appropriate surgical(s) technique(s), with the possibility of a truthful comparison of short- and long-term results of every technique with an easy correlation to the pathology treated.

	4. Choice of the surgical technique and results assessment

Top 1. Introduction 2. Pathophysiology and mechanism... 3. Functional classification 4. Choice of the... References

 
The cornerstone of all surgical repair is a careful inspection and analysis of all lesions before surgery, a careful assessment of the mechanism of dysfunction and a thoughtful determination of technique(s) to be used for correcting the dysfunction at the time of surgery. Because valve dysfunction often arises from multiple concomitant lesions, a global approach is needed to treat all the lesions and prevent failure due to an omitted lesion.

This is a guarantee of durability. Let us imagine a patient with an aortic root aneurysm (type I) and a valvular prolapse (type II). It is easy to understand that a sparing technique alone would not be enough and that an additional treatment to correct the prolapse is mandatory if we want to restore a functional aortic valve. Failure to correct a concomitant prolapse explains the high rate of residual aortic regurgitation after sparing surgery and the subsequent misattending of this technique by many cardiac surgeons.

Immediate postoperative evaluation of surgical results is also mandatory as it helps to discover an uncorrected pre-existing lesion or a newly appearing dysfunction following surgery.

A functional classification of the lesions at the level of both the cusps and the native valvular stent is required to understand the complex pathophysiology of aortic regurgitation and make the appropriate choice regarding the surgical(s) technique(s) to be used.

Lansac et al. [1] have done remarkable work studying more than 700 patients. Their paper gives an important contribution to the understanding of the pathophysiology of aortic regurgitation showing that this disease is due to both the aortic wall and the valve.

Nevertheless it is difficult to develop a lesional classification of aortic regurgitation based only on retrospective echocardiographic image analysis. Lansac et al. also showed the importance of analysing the direction of the regurgitant jet to understand the mechanism of aortic regurgitation and to evaluate postoperative results. On the other hand his analysis of the regurgitant jet, even if necessary, is not enough to comprehend all the pathology and help the surgeon in the choice of the appropriate technique(s). Even more, the classification suggested by Lansac et al. is not giving a clear light to the surgeon when this is more necessary!

Following Lansac et al. a type II with eccentric jet is either secondary to a cusp prolapse rheumatic valve disease or endocarditis. This is ignoring the fact that rheumatic lesion or endocarditis frequently leads to central jets. Similarly, Lansac's type I with central jet is not supposed to have a cusp lesion, whereas it is well known that in case of prolapse of all the three cusps we may observe a central jet and not an eccentric one as suggested in the paper. The eccentricity of the regurgitant jet is just a sign of a different level of coaptation both in aortic and mitral valves.

A functional classification should help recognise the exact lesions responsible for the insufficiency and the selection of the adequate operative manoeuvres. Carpentier established the base of the mitral repair by his functional approach of the mitral regurgitation: (1) dysfunction, (2) lesion, and (3) surgical technique. A parallelism with this philosophy in the treatment of aortic regurgitation is necessary.

	References

Top 1. Introduction 2. Pathophysiology and mechanism... 3. Functional classification 4. Choice of the... References

 

1. Lansac E, Di Centa I, Raoux F, Al Attar N, Acar C, Joudinaud T, Raffoul R. A lesional classification to standardize surgical management of aortic insufficiency towards valve repair. Eur J Cardiothorac Surg 2008;33:872-878.[Abstract/Free Full Text]

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