Complete Atrioventricular Septal Canal

Complete atrioventricular septal canal

Abstract

Complete atrioventricular canal (CAVC), also referred to as complete atrioventricular septal defect, is characterised by an ostium primum atrial septal defect, a common atrioventricular valve and a variable deficiency of the ventricular septum inflow. CAVC is an uncommon congenital heart disease, accounting for about 3% of cardiac malformations. Atrioventricular canal occurs in two out of every 10,000 live births. Both sexes are equally affected and a striking association with Down syndrome was found. Depending on the morphology of the superior leaflet of the common atrioventricular valve, 3 types of CAVC have been delineated (type A, B and C, according to Rastelli's classification). CAVC results in a significant interatrial and interventricular systemic-topulmonary shunt, thus inducing right ventricular pressure and volume overload and pulmonary hypertension. It becomes symptomatic in infancy due to congestive heart failure and failure to thrive. Diagnosis of CAVC might be suspected from electrocardiographic and chest X-ray findings. Echocardiography confirms it and gives anatomical details. Over time, pulmonary hypertension becomes irreversible, thus precluding the surgical therapy. This is the reason why cardiac catheterisation is not mandatory in infants (less than 6 months) but is indicated in older patients if irreversible pulmonary hypertension is suspected. Medical treatment (digitalis, diuretics, vasodilators) plays a role only as a bridge toward surgery, usually performed between the 3rd and 6th month of life.

Disease name and synonyms Complete atrioventricular canal (CAVC); Common atrioventricular canal; Complete atrioventricular septal defect.

1. Introduction

1.1. Definition

CAVC is a complex cardiac malformation characterised by a variable deficiency of the atrioventricular area (crux cordis) in the developing heart. The malformation involves the atrial, ventricular and atrioventricular septa and both atrioventricular valves.

Atrioventricular septal defects are congenital heart diseases in which the septal tissue immediately above and below the normal level of the AV valves is deficient or absent.

In all forms of atrioventricular septal defects there are abnormal AV valves to a varying degree. They have been also called endocardial cushion defects due to developmental disturbance in endocardial cushion, AV canal defects, ostium primum defects (when there is no VSD), and common AV valve (when there is only a single AV valve orifice) (1).

1.2. Etiology

During fetal life between 3-8 weeks, the embryologic abnormality in AV septal defects is disturbance of the proper development of the endocardial cushions, which are responsible for the septation of the atria and ventricles (membranous portion). But the exact causes are unknown (2).

1.3. History background

Abbot first recognized ostium primum ASD and common AV canal defect (3), but their morphologic similarity was recognized by Rogers and Edwards in 1948 (4). The terms partial and complete atrioventricular canal defects were introduced by Wakai and Edwards in 1956 and 1958 (5;6). The description of the position of the AV node and bundle of His, and the concept of ostium primum ASD (partial AV canal) and common AV orifice (complete AV canal) was done by Lev (7). The term intermediate and transitional was added by Wakai and Edwards and later by Bharati and Lev (8). Van Mierops studies added a great deal of knowledge to the overall anatomic features of AV septal defects during this periods (9). In 1966, Rastelli and colleagues described the morphology of AV valve leaflets in cases with common AV orifice (10). In 1976 the concept of leaflets bridging the ventricular septum introduced by Ugarte and colleagues, which was also used by Lev (11). In the late 1960s, based on anatomy and cineangiography and the description by Baron and colleagues and Van Mierop and colleagues, it was recognized that the basic defect was absence of AV septum, which can be imaged by echocardiography and in cineangiography in the right anterior oblique projection (12). These concepts were further expanded by Picoli and colleagues, and then R.H. Anderson who emphasized that all variations were part of a spectrum (13). Denni

and Varco, in 1952 used a pump- oxygenator to close what they thought ASD. The patient died, and the autopsy showed that it was partial AV septal defect. The first successful repair of a complete AV septal defect was done by Lillehei and colleagues in

1954, by using cross circulation and direct suture of the atrial rim of the defect to ventricular septal crest (14). In 1955, Kirklin and colleagues closed partial AV septal defect by open cardiotomy and use of the pump- oxygenator (15). Early mortality rates for repair were 50%. The most common complications were complete heart block, mitral valve regurgitation and creation of subaortic stenosis (16). After delineation the bundle of His by Lev in 1958, the incidence of heart block reduced. The improved understanding of the structure and function of the common AV valve and the improved surgical techniques and cardiopulmonary bypass and a realization of the importance to close the mitral valve cleft without inducing stenosis lead to decreased short- and long- term incidence of mitral regurgitation with low morbidity and mortality rates. The single- patch technique was first described by Maloney and colleagues and later on by Gerbode in 1962 (17). The two- patch technique was described early by Dubost and Blondeau in

1959 (18).

1.4. Epidemiology

Seven to 8 babies per 1000 live births have congenital heart disease, and this accounts for 3% of all infant deaths and 46% of deaths due to congenital malformations. Around

18- 25% of affected infants die in the first year with 4% of those surviving infancy dying by 16 years (Dezateux et al. (19)). Atrioventricular septal defects represent approximately 4% of all congenital cardiac anomalies, and they are frequently associated with other cardiac malformations, especially patients with Down syndrome. Complete AVSD is frequently (60%-86%) associated with Down syndrome (20;21).

Diagnosis criteria:

Diagnosis of CAVC might be clinically suspected in patients presenting in the first few months of life with congestive heart failure, cardiomegaly on chest X-ray and left axis deviation, bi-atrial enlargement and bi-ventricular pressure and volume overload on electrocardiogram (ECG). Echocardiography is the key tool for the diagnosis and anatomic classification of this malformation. It shows the ostium primum atrial septal defect, with the underlying common atrioventricular valve, and the defect of the ventricular septal inflow The anatomic subgroups (Rastelli's type A, B and C) can be classified on the basis of the chordal insertions and morphology of the superior bridging leaflet of the common atrioventricular valve (Table 1). Similarly, a thorough echocardiographic examination shows the degree of dysfunction of the common atrioventricular valve, as well as the presence of associated cardiac malformations. To date, cardiac catheterisation is not considered as mandatory for the diagnosis, but can be indicated in patients older than 6 months with suspected irreversible pulmonary hypertension. Cardiac catheterisation allows accurate quantification of the left-to-right shunt as well as assessment of the degree of pulmonary hypertension and the reversibility of the pulmonary artery resistances by hyperoxia and/or pharmacological tests. On left ventricular angiography, the appearance of the "gooseneck deformity" of the left ventricular outflow tract is peculiar of atrioventricular canal malformations.

1.5. Anatomy and Associated cardiac anomalies

1.5.1. General morphologic anatomy

The deficiency or absence of AV septum above the AV valves results in an ostium primum defect and below the AV valves it results in a deficiency of the basal (inlet) portion of the ventricular septum. The patients with partial AV septal defects have ostium primum ASD and some deficiency in the basal (inlet) portion of the ventricular septum which is less than in patients with complete AV septal defects (22). The septal deficiency may or may not result in interatrial or interventricular communications, depending on attachments of the

AV valves. From the clinical point of view, there are partial, intermediate, and complete forms of AV septal defects. In the partial form, there exists an ostium primum ASD. Here the AV valves are attached to the crest of the interventricular septum, and there is usually no interventricular communication. The anterior leaflet of the mitral valve is considered to form part of a trileaflet mitral valve, because it has a cleft of varying degree. On occasion, this mitral valve may have some degree of incompetence, but most commonly, it is competent. In the intermediate form, the main distinguishing feature from partial AV septal defects is the incomplete attachement of the AV valves to the interventricular septum. So that some gaps may exist and some degrees of underdevelopment of the leaflet tissues may be present. In the complete AV septal defect, both the lower atrial and inlet (basal) ventricular septum are deficient or absent. The attachment and configuration of the AV valves to the ventricular septum are quite variable.

There is often variability in the number of leaflets, but usually five or more AV valves leaflets of variable size are present. There may be one (common) or two AV valve orifices. For left AV valve there is left superior leaflet (LSL), left inferior leaflet (LIL) and left lateral leaflet (LLL). For right AV valve there is right superior leaflet (RSL), right inferior leaflet (RIL) and right lateral leaflet (RLL) (Figure 1).

The ratio of anterior leaflet to posterior leaflet of the left AV valve in patients with AV septal defect is reversed to normal, this means that the posterior (left lateral) leaflet contributes to one- third (1/3) and the bileaflets anterior cusp (the left superior and inferior leaflets together) contributes to two- thirds (2/3) of the mitral valve annulus (Figure 2).

The hearts with AV septal defects are characterized by absence of the usual wedged position of the aortic valve in relation to both AV valves in normal hearts. This is due to down displacement toward the apex of AV valves because of deficiency of the inlet portion of the septum, so that aortic valve is elevated and displaced anteriorly (9). In addition, the left ventricular outflow tract is narrowed and elongated, although rarely sufficient to be of hemodynamic importance in the unrepaired heart, while the LV inflow tract is shortened (13). The AV node is displaced posteriorly and inferiorly toward the coronary sinus, so that it lies between it and the ventricular crest, in the nodal triangle (Koch triangle), which is bounded by the coronary sinus, the rim of the ASD, and the posterior attachment of the inferior bridging leaflet. The bundle of His courses antero- superiorly to run along the leftward aspect of the crest of the VSD, giving off the left bundle and continuing as the right bundle branch (7) (Figure 3).

Figure 1: Mitral- tricuspid valve relationship. A: In the normal heart. B: Partial atrioventricular septal defect. C: Complete atrioventricular septal defect. (Modified from Khonsari (23)).

Figure 2: Mitral valve annular configuration. A. In the normal mitral valve. B. In an atrioventricular septal defect mitral valve. (Modified from Khonsari (23)).

Figure 3: Sketch of the course AV node and His bundle. (Modified from Lev (7)). Key: ●, AV node; ▲, penetrating portion of the AV bundle; ●▬, branching of the AV bundle; ▬ , right bundle branch; 1, SVC; 2, IVC; 3, limbus; 4, PFO; 5, cut edge of atrial appendage; 6, coronary sinus; 8, AV septal communication; 9, infundibulum; 10, base of pulmonary valve; 11, muscle of Lancisi; 12, cut edge of

moderator band.

1.5.2. Partial atrioventricular septal defect

There is usually ostium primum ASD of moderate size which is bounded superiorly by a crescentic ridge of atrial septum that fuses with the AV valve annulus inferiorly only at its margins (Figure 4). This defect is characterized by presence of two AV valves, in which the mitral valve has a cleft between the left superior and left inferior leaflets and are joined to a variable extent anteriorly by leaflet tissue near the crest of the ventricular septum, so that it is a tricuspid valve in contrast to a normal valve. In most cases there is also a patent foramen ovale or ostium secundum ASD. The interatrial communication may be small in size and is restricted to the area normally occupied by the atrioventricular septum or because of the fusion of the base of the left superior or inferior leaflets to the edge of the adjacent atrial septum (24). Rarely, AV valve tissue is attached completely to the edge of the atrial septum, and no interatrial communication exists despite the deficiency in the septum (13;25). In unusual variants of partial AV septal defect some degree of deficiency of the inlet portion of the ventricular septum may be found, especially when the inlet portion is shortened and this leads to interventricular communication, but when the left superior and inferior leaflets are attached to the downward displaced septal crest, there is usually no interventricular communication. Occasionally there are one or more small interventricular communications beneath the AV valve.

Figure 4: Partial atrioventricular septal defect. (Modified from Khonsari (23)).

Key: RS, RL, and RI, are right superior, right lateral, and right inferior leaflets respectively. LS, LL, and LI, are left superior, left lateral, and left inferior leaflets respectively.

1.5.3. Complete atrioventricular septal defect

Characterized by moderate to large interventricular communications, and common AV valve in which the left superior and left inferior leaflets are usually separated (Figure 5). The deficiency in inlet portion of the ventricular septum is usually more than in partial AV septal defect. The interventricular communication is large beneath left superior leaflet and smaller or none beneath left inferior leaflet. Very rare, there is no VSD beneath the left superior leaflet and a large one beneath left inferior leaflet (26;27).

Chordal attachments of the common AV valve in the LV are usually relatively normal, but displaced toward the apex of the heart due to deficiency of the inlet portion of the septum, this leads to no longer aortic valve between the AV valves (28-30). In LV a third papillary muscle may be present and the posterior papillary muscle is displaced laterally. There may be only one papillary muscle which is producing a parachute type valve that is difficult to repair. Rarely, the left AV valve is stenotic, but this is usually associated with hypoplasia of the LV (31). The right AV valve has also superior, inferior, and lateral leaflets. The right superior leaflet is small when the left superior leaflet bridging is extensive and large when the left superior leaflet bridging is mild or absent.

Figure 5: Complete atrioventricular septal defect. (Modified from Khonsari (23)). Key: RS, RL, RI are right right superior, right lateral, and right inferior leaflets, respectively. LS, LL, LI are left superior, left lateral, and left inferior leaflets, respectively.

1.5.4. Rastelli classification

This classification based on whether the left superior leaflet bridges or not over the septal crest to the right ventricular side. It essentially focuses on the shape, size, location and details of the attachments of the left superior leaflet.

In type A, which is very often seen, the left superior leaflet is over the left ventricle and its chordal attachment is to the crest of the ventricular septal defect.

In type B, which is rarely seen, the chordal attachment of the left superior leaflet is to an abnormally located papillary muscle on the right ventricular aspect of the interventricular septum.

In type C, which is seen quite often, the left superior leaflet is large and bridges the ventricular septal defect and right ventricle and its chordal attachement are variable (10) (Figure 6).

Figure 6: Atrioventricular valves viewed from atrial side. A. Normal mitral and tricuspid valves. B. Leaflets in partial atrioventricular septal defects. C. Rastelli´s classification of complete atrioventricular septal defects. (Modified from Kirklin/ Barratt-Boyes (32)).

1.5.5. Associated cardiac anomalies

Patent ductus arteriosus is present in about 10% of cases especially in complete AV septal defects. Tetralogy of Fallot is present in about 5% of patients with AV septal defects. Double outlet right ventricle without pulmonary stenosis is found in about 2% of patients. Completely unroofed coronary sinus with left superior vena cava is found in 3% of cases of the complete AV septal defects and 3% of cases of the partial AV septal defects (25). Pulmonary vascular disease is common in complete AV septal defect and usually appears early in life and progresses. Down syndrome is found in 75% of cases with complete AV septal defect, but is rare in cases with partial AV septal defects. Left ventricular outflow tract obstruction is rare in unoperated patients (about 1%) (25), but it becomes apparent as a postoperative complication (33).

1.6. Pathophysiology, Natural history and Diagnostic methods

1.6.1. Pathophysiology

Unless severe pulmonary hypertension or associated pulmonary stenosis, there is usually left to right shunt. In partial AV septal defect, it is at the atrial level and usually large, but sometimes it is small or moderate. If the shunt is large, and there is no AV valve

regurgitation, then it is hemodynamically similar to ASD of the secundum type, and only the RV stroke volume is increased. In case of important left AV valve regurgitation, the left to right shunt will be more, and the stroke volume of both LV and RV will be increased, and cardiomegaly and heart failure develop early. In case of complete AV septal defect, the left to right shunt is both at atrial and ventricular level and pulmonary artery pressure approaches the systemic pressure and if not corrected early the pulmonary resistance will be fixed and the risk of repair is increased (34).

1.6.2. Natural history

The natural history depends mostly on the extent of the three components of the septal defects; atrial shunt, ventricular shunt, and the AV valve regurgitation. In complete AV septal defects they usually are presented early in life with severe heart failure with or without pulmonary infections, which is complicated if it is associated with Down syndrome, because of the early tendency to develop fixed pulmonary vascular resistance. In the other end of the spectrum, the partial AV septal defect, the prognosis depends on the extend of shunt volume and AV valve regurgitation. The patients are usually asymptomatic and presented later in childhood or young adulthood. By complete AV septal defects the mean life expectancy by some patients is less than 6 months or even less in patients with a fixed pulmonary vascular resistance who developing symptoms of Eisenmenger- reaction (right to left shunt).

1.6.3. Diagnostic methods

The exact diagnosis of AVSD can be made with two- dimensional echocardiography (35). Clinical presentation, chest radiograph, and electrocardiogram let suspect AVSD (36). The need for cardiac catheterization is not necessary before 6 months of age because the probability to develop fixed high pulmonary resistance is low, but it can be used when major cardiac anomalies coexist or evidence of pulmonary vascular disease or the echocardiographic examinations are not clear (29).

2. Therapy options

2.1. Medical therapy

Patients with partial AV septal defects present with signs and symptoms similar to those of secundum ASD´s and as such, they rarely need medical therapy. In patients with complete AV septal defects, medical therapy consists of anticongestive treatment for the signs and symptoms of congestive heart failure. The mainstays of medical therapy are Diuretics (for diuresis for the volume overloaded heart), digoxin (as a mild inotrope), and ACE- inhibitors (for afterload reduction), as reported by Montigny et al. (37). In our institution low dose B- blockers are successfully used due to blocking the sympathetic activity and by reducing systemic vascular resistance without decreasing blood pressure which is also described by Buchhorn et al. (38).

2.2. Surgical therapy

2.2.1. Surgical indications

The diagnosis of an AV septal defect is in principle an operation indication, because spontaneous closure does not occur and the hemodynamic derangement is nearly always present. By partial AV septal defect the optimal age for operation is 1 to 2 years, but this could be earlier if there is AV valve regurgitation, heart failure or severe growth failure.

In complete AV septal defect, operation is indicated early in the first year of life, usually before 6 months of age, but if refractory heart failure or severe growth failure is evident early, then repair at 2 to 4 months of age is indicated. Operation after the first year of age is associated with increased risk, because the pulmonary vascular disease may be already too severe to permit repair.

2.2.2. Aims of surgical repair

1- Closing the interatrial communication, which is always present.

2- Closing the interventricular communication, when one is present.

3- Creating, or maintaining two competent, nonstenotic AV valves.

4- Avoiding AV block induction by damage to the AV node and or His bundle.

For these purposes there are many repair techniques, which, when used properly, provide good results (39;40), for example:

a. One or two patches may be used to repair the malformation when there is a large VSD (41).

b. A large bridging left superior leaflet, may be divided to facilitate the repair or left intact

(25;42;43).

c. Damage to AV node and His bundle may be avoided by staying on the right side of the septum (25).

d. The cleft between the LSL and LIL, may be sutured or may be left as tricuspid valve to avoid valve stenosis (44;45).

e. The AV valves may be attached to the patch by simple or by pledgeted mattress sutures with some sort of sandwich method, to establish AV valve competence (25;44).

2.2.3. Surgical techniques

2.2.3.1. Two- patch technique for complete AVSD repair

After a median sternotomy, a piece of pericardium is taken and cleared from pleural fat, and set aside in 0.6% glutaraldehyde, after the remaining pericard is widely opened, stay sutures are placed and the anatomy is examined. The patient is heparinized and arterial cannula inserted. Two venous cannulae are used, one inserted through the right atrial appendage in the SVC, the other through the low right atrial wall in IVC. Direct caval cannulation can be done also. CPB is established with 34°C cold perfusate, and the patient cold to 31°C. The cardioplegic needle is now placed in the ascending aorta, the aorta is clamped, and the cold cardioplegic solution is infused. The caval tapes are snugged.

After that the right atrium is opened, the malformation is examined and each morphologic details are noted. Valve leaflets are often closed as they are in systole. If not, saline is injected into LV to close them, then the morphology of the leaflets is studied to plan the repair of any regurgitation or to accommodate any lack of left AV valve tissue. A fine polypropylene suture is placed between LSL and LIL and left loose. The leaflets are allowed to open and atrial and ventricular septal defects are studied. Position of coronary sinus is noted, and the course of AV node and His bundle is imaginated from knowledge of the anatomy. The leaflets are retracted and the depth of the ventricular septal defect estimated. Dacron patch is trimmed to a crescent shape of appropriate size. Suture line may begin anywhere, but it must be on the right ventricular side of all chordae from left side leaflets, including those from any bridging components of the LIL. Suture line should stay well back from ventricular crest and catch some of the base of the RIL to avoid His bundle injury. Suture line is completed anteriorly, here care must be taken to avoid LVOTO. The LSL and LIL are precisely fixed to the patch by using interrupted simple or mattress sutures. Here care must be taken to ensure that the mitral valve apparatus at the patch is

appropriately narrow so as not to create regurgitation and at the correct height so as not to produce LVOTO (too low) or mitral regurgitation (too high). Mitral valve cleft is closed by interrupted simple sutures, testing mitral valve for competence. The RSL and RIL are fixed to the Dacron patch, and any cleft closed also. The pericardial patch is trimmed to size the atrial defect, and a new suture line is begun with bites incorporating pericardial patch, the right AV valve, the Dacron patch and little fom left AV valve. The pericardial patch is sutured anteriorly, superiorly, and inferiorly by leaving coronary sinus draining into left atrium to avoid conduction system injury (Figure 7: A- D). After that rewarming is carried out, right atrium closed, the heart is filled, and the aortic cross clamp is removed after deairing procedures are performed. Then operation assessment is performed by

transesophageal echocardiography.

Figure 7- A: The common AV valve is floated to a closed position using saline solution. The central apposition points of the superior and inferior bridging leaflets are identified and marked with fine polypropylene. (Modified from Ohye (46)).

Figure 7- B: Two-patch technique. A patch of Goretex or Dacron is fashioned and secured along the crest of the ventricular septal defect. (Modified from Ohye (46)).

Figure 7- C: Two-patch technique. Interrupted horizontal mattress sutures are placed through the crest of the VSD patch and the inferior and superior bridging leaflet, dividing the common AV valve into right and left components. (Modified from Ohye (46)).

Figure 7- D: The pericardial patch is sutured to the crest of the prosthetic ventricular septum with the superior and inferior bridging leaflet sandwiched between the 2 patches. (Modified from Ohye (46)).

2.2.3.2. Single- patch technique for complete AVSD repair

Repairing differs from 2- patch technique in the following:

1. Single patch almost always pericardium.

2. The waist tailoring at the level of AV valve is critical.

3. Both left and right AV valves are sutured to the pericardial patch.

The preparation for bypass is the same as for two- patch technique. After aortic cross clamping and cardioplegic infusion, oblique right atriotomy is done, identifying the most anterior point of LSL and LIL, and 6-0 Prolene suture is placed and left loose, then the AV valve is tested by saline infusion. The bridging LSL and LIL is incised to allow access for suturing the pericardial patch (after trimming) to ventricular septal defect, to be later fixed again in the patch. The patch sutured on the right side of the septum, with care taken, to avoid injury to His bundle. The leaflets of both right and left AV valve are attached to the patch at its waist. The AV valve clefts are closed with interrupted simple suture and tested

with saline for competence. The same patch is also used to close the atrial septal defect, leaving the coronary sinus draining into the left atrium, in the same way as in two- patch technique (Figure 8: A- D).

After that rewarming, right atriotomy closure, deairing and aortic cross clamp removed. Then operation assessment by transesophageal echocardiography, if severe abnormalities are present, they should be corrected. Then the operation is completed in the usual manner

after placing pulmonary artery catheter.

Figure 8- A: Single- patch technique. The superior and inferior bridging leaflets are divided into right and left component. (Modified from Ohye (46)).

Figure 8- B: The leaflets are resuspended to the patch by passing sutures through the cut edge of the AV valve leaflet, the patch, and the cut edge of the right AV valve and tying the sutures. (Modified from Ohye (46)).

Figure 8- C: The cleft of the mitral valve between the superior and inferior bridging leaflets is closed. (Modified from Ohye (46)).

Figure 8- D: The atrial septal defect is closed with an autologous pericardial patch. The coronary sinus is placed in the left atrium to avoid injury to the conduction system. The rim of the ASD, the AV node, the bundle of His are indicated. The dashes represent the proposed suture line. (Modified from Ohye (46)).

2.2.3.3. Repair of partial AV septal defect

It is a single patch repair in which the atrial septal defect is closed by a pericardial patch and the mitral valve cleft is closed at the thickened and rolled edges. The same precaution to avoid injury to AV node and His bundle is taken, by suturing the pericardial patch, so that the coronary sinus is draining to the left atrium, as in complete AV septal defect repair. The coronary sinus can be left draining to right atrium also.

In more recent years, a better understanding of the surgical anatomy of CAVCD as well as the improvements in surgical techniques, myocardial protection and postoperative care have led to a steady reduction in operative mortality [1,6]. In most cases, congestive heart failure soon after the fall of pulmonary vascular resistance (fourth to sixth week of life) and the increase in QP/QS (ratio between pulmonary and systemic cardiac output) due to a large left-to-right shunting are poorly controlled by medical therapy and therefore surgical repair is beneficial soon after this time [3,6]. As demonstrated by Michielon et al. [6] repair at an early age is associated with a very good likelihood of preoperative competence of common A-V valves, despite the presence of a ‘cleft’ in the left A-V component. In fact, a competent common A-V valve seems to be less frequent with increasing age at operation. We think that the powerful stimulus of chronically elevated QP/QS plays an important role in the onset of annular dilatation and secondary left AV valve incompetence [6]. In other words, early correction could eliminate, at least partially, the incidence of LAVVR in the postoperative follow-up period, which remains the most important factor for postoperative morbidity and mortality .