CONGENITAL HEART DISEASE
Year : 2002 | Volume
: 3 | Issue : 2 | Page : 9-
Congenital heart disease - E :Congenital aortic sinus of valsalva aneurysm and prolapse
S.E C Spitaels
Department of Cardiology, Thoraxcentre, Erasmus Medical Centre Rotterdam, Rotterdam, The Netherlands
S.E C Spitaels
Department of Cardiology, Thoraxcentre, Erasmus Medical Centre Rotterdam, Rotterdam
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Spitaels SC. Congenital heart disease - E :Congenital aortic sinus of valsalva aneurysm and prolapse.Heart Views 2002;3:9-9
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Spitaels SC. Congenital heart disease - E :Congenital aortic sinus of valsalva aneurysm and prolapse. Heart Views [serial online] 2002 [cited 2023 Sep 22 ];3:9-9
Available from: https://www.heartviews.org/text.asp?2002/3/2/9/64511
Aortic root pathology is more common than primary aortic valve disease and accounts for more than one-half of the patients undergoing valve replacement  . In these cases aortic valve insufficiency results from progressive dilatation of the aortic sinuses and distortion of the annulus  . The most common causes of acquired degenerative disease leading to dilatation are a normal phenomenon of ageing, especially in the presence of systemic hypertension, or "idiopathic"  . Profound dilatation of the weakened aortic walls may occur on the basis of aortic medial necrosis (isolated or in association with Marfan syndrome), annuloaortic ectasia and along with rare systemic disorders. Less common and less known is a rare congenital disorder due to the presence of a weak point in the aortic wall resulting from a localized interruption of the media, that can lead to the typical congenital aneurysm of the sinus of Valsalva with eventual rupture  or to the syndrome of prolapse of the right coronary cusp in the presence of a subarterial doubly-committed ventricular septal defect  . In this review we will focus on the congenital nature of the disease with a short description of the normal structure of the aortic root, the pathophysiologic changes that occur in the presence of a congenital anomaly of the aortic wall, the clinical presentation, the technique of echocardiographic imaging and the surgical treatment.
Anatomy of the normal aortic root
The aortic root is a three-dimensional structure made up of the sinuses of Valsalva, the leaflets of the valve and the interleaflet triangles. The three sinuses of Valsalva occupy the greater part of the aortic root. They are dilatations of the aortic wall confined proximally by the bases of the semilunar valve leaflets and distally by the sinotubular ridge  . Inside they provide a hollow space enclosed by the aortic cusps and the opposite aortic wall  . They accommodate the open leaflets providing space behind them and, as such, preventing occlusion of the coronary artery orifices. They allow formation of eddy currents within them, which prevents the leaflets striking the aortic wall and promotes valve closure. The sinuses are named according to their relation with the coronary artery: the right, the left and the non-coronary. Alteration in any part of the aortic root will affect their function. For example: dilatation of the sinuses, even in the presence of normal valve leaflets, will prevent coaptation of the leaflet edges in diastole .
The basic congenital abnormality causing an aneurysmal dilatation of the sinus of Valsalva is a weak point in the aortic wall due to a localized interruption of the media. The aneurysm localized in one aortic sinus, which is not dilated itself, projects as a finger like extension and has a perforation at its tip [Figure 1]. Rupture rarely occurs and is seen in the majority of patients well after puberty. Of these congenital aneurysms, 90 to 95% originate in the right or non-coronary sinus. Those arising in the right coronary sinus may rupture into the right ventricle or right atrium, those arising in the non-coronary sinus into the right atrium. An aneurysm originating from the left sinus is an extremely rare finding. Deformation of the right or non-coronary sinus of Valsalva is associated with a ventricular septal defect (VSD) in about 50% of patients [Figure 1]. The VSD is small and always situated high in the ventricular septum. The right sinus of Valsalva may prolapse through a subarterial doubly committed VSD (supracristal type) and both the right and non-coronary sinus through a perimembranous VSD with extension to the outlet. Characteristic for the subarterial VSD is the absence of the outlet septum resulting in fibrous continuity between the aortic and pulmonary valves, which are situated on the same level. Hence, the upper margin of the defect is made up by the right coronary cusp and part of the dilated sinus of Valsalva and the lower border by the crest of the ventricular septum with no intervening muscular tissue. Both sinus of Valsalva aneurysm and subarterial VSD are more common in the Asiatic population. Not only the media of the aortic sinus fails to reach the aortic annulus, but additional failure of the annulus to attach to the ventricular septum is present [Figure 2]. These basic abnormalities result in the aortic sinus and annulus in this region not being supported, causing progressive changes, which are further aggravated by hemodynamic factors  . During early systole a Venturi-effect is produced by the left-to-right shunt through the small VSD, displacing the unsupported annulus outward and downward, with prolapse into the VSD later in systole. In diastole the high pressure in the aortic root produces further distension and displacement towards the right ventricular outflow-tract. Failure of coaptation of the valve leaflets, caused by progressive elongation of the free margin in the right coronary cusp, results in progressive valve regurgitation and secondary changes in the form of thickening and retraction of the free borders of all three cusps2.
The clinical picture reflects either a sudden large perforation or a gradual development of a small perforation  . Unruptured aneurysms, as a rule, do not cause symptoms. With echocardiography they are now being diagnosed with increasing frequency. Occasionally an unruptured aneurysm can cause severe complications such as: 1) obstruction of the right ventricular outflow  ; 2) tricuspid stenosis and insufficiency secondary to prolapse of the aneurysm through the tricuspid valve  ; 3) conduction abnormalities due to the proximity of the right coronary cusp to the common bundle of His and proximal portions of the right bundle and left anterior fascicle with several reported cases of complete heart block  ; and 4) coronary artery compression or obstruction of the ostium of the right coronary artery by thrombus within the right sinus of Valsalva aneurysm  . Acute large rupture can have a dramatic onset with severe chest pain, dyspnea and even pulmonary edema culminating in death after a short period of time. On the other hand, a small perforation may initially go unnoticed. Gradual progression will permit a better hemodynamic adjustment. Rupture is characterized by the sudden appearance of a continuous murmur in an otherwise healthy individual. Either the systolic or the diastolic portion of the continuous murmur tends to be louder. The intensity may diminish around the second sound, to increase again in diastole creating a to-and-fro impression  . The association of a progressively diminishing systolic VSD murmur with the appearance of a soft diastolic aortic insufficiency murmur should alert the physician to the occurrence of a prolapsing aortic cusp into the VSD. The jugular pulse tracing can be of help in differentiating between a rupture to the right atrium and to the right ventricle [Figure 3]. In the case of rupture into the right ventricle, the severe diastolic ventricular volume-overload causes obliteration of the y-descent indicating that the ventricle has become so "stiff" that it is incapable of expanding rapidly in response to the incoming blood from the right atrium in early diastole. On the contrary, rupture into the right atrium obliterates the x-descent. The high volume of blood shunted into the right atrium results in an incomplete emptying of the atrium that fills quickly from above as it begins to relax, causing it to become rapidly over distended. The high right atrial pressure promotes early tricuspid opening with a premature v-wave, and a high peaked a-wave, associated with a fourth heart sound.
Echocardiography is the most reliable method to confirm the diagnosis. Cross sectional echocardiography and color Doppler allow accurate recognition and definition of the different components of the disease. There is no need for diagnostic catheterization and angiography. The criteria for the diagnosis of an aneurysm are: (a) the root of the aneurysm must be located above the aortic annulus, (b) the aneurysm is saccular, (c) the size of the aorta above the aneurysm is normal  . An aneurysm of the right sinus, communicating with the right ventricle, protrudes anteriorly and leftward in a short axis view, caudally in a parasternal long-axis view [Figure 4]. An aneurysm of the noncoronary sinus, communicating with the right atrium, protrudes posteriorly, caudally and to the right [Figure 5]. Color flow imaging reveals the shunt from the aortic sinus into the right atrium or ventricle and Doppler echocardiography detects a continuous high velocity flow in the chambers with which the ruptured sinus communicates. In the presence of a prolapse of the right coronary cusp the characteristic dilatation of the right sinus with sagging of the annulus and cusp into the right ventricle can be recognized in the parasternal long-axis view  . The localization of the VSD is best visualized in the short axis view: a perimembranous VSD with extension to the outlet is located between the midline and the tricuspid valve; a doubly committed subarterial VSD between the midline and the pulmonary valve. The characteristic high-systolic and low-diastolic velocity associated with a left-to-right shunt through this restrictive VSD can be detected at the level of the subpulmonary ventricular septum just below the right sinus of Valsalva in the parasternal long-axis view and differs from the continuous high-velocity flow in systole and diastole after rupture of the aneurysm of the right sinus  . In addition the magnitude of aorti regurgigation can be assessed and right heart pressures estimated.
We favour the policy that any patient with a subarterial VSD needs regular echocardiographic follow-up, because of the progressive nature of the anomalies. Once the characteristic dilatation of the sinus occurs, there is indication for surgery even in asymptomatic patients without signs of prolapse or aortic regurgitation. Some advocate routine closure of any subarterial VSD as prophylaxis to prevent aortic valve prolapse. However, this remains controversial. In the past some surgeons preferred to approach the aneurysm (and or VSD) through the cardiac chamber into which it ruptured  ; others incise the aorta or use a combined approach. The aneurysmectomy and/or VSD closure is done directly with sutures or a patch, combined with repair or replacement of the aortic valve. More recently, a simple and safe technique was designed  . All the anatomic and functional components of the anomalies, including severe aortic regurgitation when present, could be corrected and patch-insertion avoided. Using a transaortic approach the sutures are placed through the ventricular crest, aortic annulus and sinus of Valsalva [Figure 6]. The continuity between these structures is restored resulting in closure of the VSD, plication of the aortic sinus and correction of the outward and downward displacement of the aortic annulus. The annulus and the cusp are elevated and displaced centrally toward the lumen of the aorta, which has the effect of increasing cusp coaptation. Yacoub's technique, at the time of the operation, was sufficient to restore competence of the aortic valve in 65% of the patients. In the remaining, repair of the aortic valve was necessary. Late aortic insufficiency is still a risk.
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