Congenital Sinus of Valsalva Aneurysm and Aortico–Left Ventricular Tunnel

Definition

Congenital sinus of Valsalva aneurysms are thin-walled saccular or tubular outpouchings usually located in the right sinus or adjacent half of the noncoronary sinus. They generally have an intracardiac course but may protrude into the pericardial space. They may rupture into the right (or rarely the left) heart chambers to form an aortocardiac fistula, or into the pericardial cavity. Associated congenital cardiac anomalies are common.

Historical Note

The syndrome of acute rupture of a congenital sinus of Valsalva aneurysm was apparently first described by Hope in 1839. A year later, Thurman published the first important paper on the subject. He discussed Hope's case and added five of his own, none of which had ruptured. Eighty years later, Abbott reviewed the clinical features of acute rupture from eight previous cases and reported another case. At that time, and even as late as 1937, most ruptured and unruptured sinus of Valsalva aneurysms were considered syphilitic. Smith stated in 1914 that “the lesion, which is usually syphilitic, is not so rare as to be altogether devoid of clinical interest, but the diagnosis, perforating or otherwise, presents almost insurmountable difficulties.” Jones and Langley reviewed congenital and acquired aneurysms in 1949. They accepted 25 cases as being of congenital origin and elucidated most of the important features of the condition. In 1951, Venning may have been the first to diagnose acute rupture during life, although Oram and East claimed this distinction in 1955, as did Brown and colleagues. In Oram and East's patients, cardiac catheterization confirmed the presence of a left-to-right shunt, although angiography was not performed. The earliest report of using aortography to diagnose an unruptured aneurysm was that of Falholt and Thomsen in 1953.

The first successful surgical repairs of sinus of Valsalva aneurysms were performed in 1956 at the Mayo Clinic and the University of Minnesota, using cardiopulmonary bypass (CPB). Spencer, Blake, and Bahnson and Morris and colleagues also reported early successful cases. In 1957, both Morrow and colleagues and Bigelow and Barnes successfully closed a ruptured congenital sinus of Valsalva aneurysm using mild hypothermia with inflow stasis, but this technique was not subsequently employed. Numerous reports followed of one or two patients treated successfully using CPB. Dubost and colleagues reported eight cases in 1962, and Besterman and colleagues reported six cases in 1963. In a 1960 collective review, Kieffer and Winchell reported 78 surgical and nonsurgical patients, 59 of whom had rupture of the aneurysm into a cardiac chamber. Sakakibara and Konno noted the prevalence of this lesion in Japan and its association with ventricular septal defect (VSD) and aortic regurgitation (AR), and were among the first to provide a comprehensive classification. Their first patient underwent aneurysm repair in 1960.

Morphology

The essential lesion of congenital sinus of Valsalva aneurysms is separation of the aortic media of the sinus from the media adjacent to the hinge line of the aortic valve cusp, as emphasized by Edwards and Burchell in 1957 ( Fig. 36-1 ). This defect may result from absence of normal aortic elastic tissue and media in this region. The congenitally weak area gradually enlarges under aortic pressure to form an aneurysm, although the age at which this occurs is uncertain. Viewed from the aorta, the aneurysm appears as an excavation of the sinus of Valsalva that protrudes into the underlying cardiac chamber ( Fig. 36-2 ).

Precise location of this basic congenital abnormality, which may be accompanied by an adjacent separation of the ventricular septum from the aorta to form a VSD, tends to be different in Asians and non-Asians. In Asians, the basic abnormality is located leftward and toward the commissural area between the right and left coronary cusps, so compared with non-Asians, rupture occurs more often into the right ventricle than right atrium (94% vs. 77%, P[χ ² ] = .0001). The coexisting VSD in Asian patients is usually leftward and juxta-arterial, whereas in non-Asians it is usually rightward and only juxta-aortic (see Chapter 35 for definitions). The leftward tendency in Asians is also manifested by fewer aneurysms of the more rightward noncoronary sinus than in non-Asians (11% vs. 32%, P < .0001). Left sinus of Valsalva aneurysms are uncommon in both Asians (2%) and non-Asians (5%) ( P[χ ² ] for difference = .11).

Acquired sinus of Valsalva aneurysms caused by medionecrosis, syphilis, arteriosclerosis, endocarditis, Behçet disease, or penetrating injuries are usually readily distinguishable from congenital forms. They are more diffuse, involving more of the sinus or multiple sinuses and often the ascending aorta, and therefore project into the pericardium outside the heart. A congenital aneurysm is frequently diagnosed by exclusion of other etiologies as well as by presence of associated congenital cardiac defects. Difficulties arise in establishing a diagnosis of mycotic aneurysms, because endocarditis complicates about 5% to 10% of congenital aneurysms. Similarly, difficulty exists in diagnosing the presence of medionecrosis (cystic medial degeneration), because it and Marfan syndrome are both present in some patients with congenital sinus of Valsalva aneurysms.

Rupture

In some patients, the aneurysm gradually develops a localized windsock, which ultimately ruptures into an adjacent low-pressure cardiac chamber ( Fig. 36-3 ). The thin-walled, ruptured aneurysm characteristically has an intracardiac fistulous portion and a nipplelike projection into the cardiac chamber, with one or more points of rupture at its apex ( Fig. 36-4 ). Rarely it projects outside the aortic root or heart. When the aneurysm coexists with a VSD, the windsock usually projects into the right ventricle through a thinned area of myocardium just downstream from the VSD; the aneurysm is separated from the VSD by the hinge line of the aortic valve cusp, at the septal portion of the left ventriculoaortic junction ( Fig. 36-5 ; see also Fig. 36-2, C ).

About one fourth of patients have no windsock or other suggestion of aneurysm formation, but rather have a direct fistulous communication between the aortic sinus and the heart. This defect has been recognized in a few patients at or soon after birth. Windsock deformity is typical in lesions originating from the right sinus and communicating with the right ventricle; a direct fistula is typical in those from the noncoronary sinus to the right atrium, and an extracardiac aneurysm is typical in the rare cases of left sinus origin.

Although the prevalence of aneurysms of the sinus of Valsalva in various locations is different among Asians and non-Asians, in both groups the sinus of origin is the main determinant of the direction of protrusion and rupture of the aneurysm, and thus of the chamber into which it ruptures ( Fig. 36-6 ). Also in both populations, but with differing prevalence, aneurysms of the right aortic sinus of Valsalva are most common. The aneurysm may arise from the leftward portion of this sinus, with the windsock projecting into the adjacent right ventricular outflow tract just below the pulmonary valve, termed type I by Sakakibara and Konno. It may also originate more centrally and project through the substance of the outlet portion of the right ventricular aspect of the ventricular septum ( Fig. 36-7 ), or from the rightward portion of the sinus, entering the right ventricle beneath the parietal band (parietal extension of the infundibular septum) in the region of the membranous septum. Rarely the aneurysm may project into the pulmonary trunk.

Aneurysms from the noncoronary sinus usually originate from its anterior portion and project into the right atrium ( Fig. 36-8 ), but in rare cases they project and rupture into the right ventricle. Rarely, rupture can occur simultaneously into the right ventricle and right atrium or into the muscular ventricular septum. Aneurysms arising from the posterior portion of the noncoronary sinus may rupture into the pericardium. Another rare occurrence is a right sinus or noncoronary sinus aneurysm that ruptures into the left ventricle. Rarity of rupture into the left ventricle may be related to the relatively thick wall and high pressure in that chamber. Aneurysms arising from the left coronary sinus may rupture into the left atrium, left ventricle, or rarely the pulmonary trunk or pericardium.

Sinus of Valsalva aneurysms rupturing into areas adjacent to the tricuspid valve are also adjacent to the atrioventricular (AV) node and His bundle and may be a cause of heart block, bundle branch block, and ventricular fibrillation.

Table 36-1 shows the overall distribution of the various sites of rupture, based on analysis by Chu and colleagues of 361 cases in the literature, including 57 from their own institution.

Table 36-1

Prevalence of Sites of Rupture for Sinus of Valsalva Aneurysms

Data from Chu and colleagues.

Site of Rupture	Asian (% of 195)	Non-Asian (% of 166)	Total (% of 361)
Right atrium	13	35	23
Right ventricle	84	57	72
Right ventricle + right atrium	<1	1	<1
Left atrium	<1	1	<1
Left ventricle	<1	2
Right atrium + left atrium + left ventricle	<1	<1
Ventricular septum	1	1	<1
Pulmonary trunk	<1	<1	<1
Right ventricle + pulmonary trunk	<1	<1	<1
Pericardium	<1	2	<1

Clinical Features And Diagnostic Criteria

Unruptured congenital sinus of Valsalva aneurysms are usually silent lesions; their diagnosis depends on echocardiograms or aortograms usually obtained to demonstrate associated symptomatic lesions such as VSD or AR. Diagnosis can be made incidentally during echocardiography or coronary angiography. Rarely, unruptured aneurysms produce tricuspid valve dysfunction or right ventricular outflow obstruction, bringing the patient to medical attention. These aneurysms may also produce severe myocardial ischemia by compressing the right or left main coronary artery. Embolization from unruptured sinus of Valsalva aneurysms and complete heart block have also been reported. Presence of this anomaly should be considered in men, who represent 80% of patients with sinus of Valsalva aneurysms.

Acute symptoms occur in about 35% of patients with rupture of the aneurysm. In 45% of patients, surprisingly, rupture is associated only with gradual onset of effort dyspnea, and in 20%, no symptoms develop. Acute symptoms consist of sudden breathlessness and pain. The pain is usually precordial and may also be epigastric, probably because of acute hepatic congestion. Precordial pain may mimic myocardial infarction, although radiation of the pain beyond the substernal area is unusual. In a few patients, death occurs within days of rupture from right-sided heart failure, but most patients improve during the latent period, which may last for weeks, months, or years. This improvement may occur without specific medical therapy. The latent period is usually followed by recurrence of dyspnea and signs of right-sided heart failure. Characteristic features at this final stage are aortic and tricuspid regurgitation, an unusual combination.

The infrequency of severe symptoms at rupture may be due to the initially small size of the rupture in many patients. Studies by Sawyers and colleagues in dogs indicate that symptoms are severe when the fistula is greater than 5 mm in diameter. However, in humans, Taguchi and colleagues found little correlation between size of the fistulous opening at operation and a history of acute symptoms. Acute symptoms at rupture may occur less often with a VSD and more often with severe AR.

Acute symptomatic ruptures may be precipitated by heavy exertion, but they also occur after serious automobile accidents and at cardiac catheterization. Rarely, an episode of infective endocarditis may be the precipitating factor. Marfan syndrome may also predispose the aneurysm to rupture.

Rupture is heralded not only by pain and dyspnea but also by a characteristic murmur that is loud, harsh, superficial, and accompanied by a coarse thrill. The murmur is usually continuous with either systolic or diastolic accentuation, but it may be to and fro, similar to that present in the VSD-AR syndrome. In the past, this murmur has been mistaken for that of patent ductus arteriosus, but it is maximal at a lower site, usually the left second, third, or fourth intercostal space. With rupture into the sinus portion of the right ventricle or right atrium, the murmur tends to be maximal at a low level over the sternum or to the right of the lower sternum. Rarely the murmur is systolic only, possibly because the communication is small. Alternatively, the murmur may be confined to diastole in those few cases when rupture occurs into the high-pressure left ventricle or when right ventricular pressure is at systemic level, as in the neonate.

When the murmur is continuous, its timing and accentuation are a function of several factors including degree of associated AR, degree of aortic systolic murmur, functional size of the VSD, and size of the fistula. Morch and Greenwood assessed the various causes of murmurs that were believed to be continuous and associated with signs of rapid aortic runoff in their adult patients and found that ruptured sinus aneurysm (8 cases) was the second most common cause after patent ductus arteriosus (33 cases), followed by VSD and AR (3 cases), aortopulmonary window (3 cases), coronary arteriovenous fistula (1 case), and pulmonary arteriovenous fistula (1 case).

Other physical signs of ruptured aneurysm include widened aortic pulse pressure, suggesting mild to severe AR. An elevated jugular venous pressure with a prominent v wave, suggesting tricuspid regurgitation, may be caused by direct entrance of a fistula into the right atrium, but in most cases this sign is absent until onset of right-sided heart failure, when liver enlargement and pulsation also occur.

The chest radiograph does not show enlargement of the aortic root. Plethora may be present, although the left-to-right shunt through both the fistula and any associated VSD is usually small. The electrocardiogram shows either left ventricle or biventricular hypertrophy. Right bundle branch block may occur and may be more common in aneurysms with an intracardiac course close to the AV node and bundle of His. Complete heart block can also occur.

Although the diagnosis is virtually certain on clinical grounds in patients with acute symptoms and sudden appearance of a continuous murmur, two-dimensional Doppler color flow echocardiography is used for verification ( Fig. 36-9 ). Cardiac catheterization and angiography are generally performed to study the site of origin and termination of the fistula and the presence of associated anomalies, particularly VSD, AR, and pulmonary stenosis (see Figs. 36-2, 36-4, 36-7, and 36-8 ). The true size of the VSD cannot be estimated angiographically when the right aortic cusp is prolapsed into the VSD. Degree of left-to-right shunting through the fistulous communication with the VSD is calculated, as is pulmonary vascular resistance (see “Cardiac Catheterization” under Clinical Features and Diagnostic Criteria in Section I of Chapter 35 ). Magnetic resonance imaging may establish the diagnosis of aneurysm in certain circumstances.

Natural History

In an era in which unruptured sinus of Valsalva aneurysms are being diagnosed with greater frequency (42% of those diagnosed by Chiang and colleagues were unruptured ), it is unfortunate that the time-related probability of aneurysmal rupture is unknown. Such information would be useful not only in advising patients for or against operation, but also in managing an unruptured aneurysm at the time of surgical treatment of a coexisting cardiac anomaly. Occasionally, unruptured aneurysms of the sinuses of Valsalva cause important symptoms by protruding into either the right atrium, which causes tricuspid stenosis and regurgitation, or the right ventricle, which causes right ventricular outflow obstruction. Complete heart block and ventricular tachycardia may result from the sheer mass of a large and strategically located aneurysm of a sinus of Valsalva.

When it ruptures, the aneurysm usually does so in the third or fourth decade of life. An exception is when there is already a small fistulous communication present at birth. This is generally well tolerated and is not a cause of early death. As already noted, in about 20% of patients, the time of rupture cannot be determined by history. Once symptoms develop, heart failure worsens, and without surgical treatment, most patients die within 1 year of rupture.

Although death after intracardiac rupture of a sinus of Valsalva aneurysm is usually from heart failure, infective endocarditis complicates heart failure in about 10% of patients and may itself be a cause of death.

When a VSD coexists with the aneurysm, the aortic valve is usually at least mildly regurgitant. The natural history then becomes similar to that of VSD and AR (see Section II of Chapter 35 ). The AR becomes progressively more severe, as does prolapse of the right aortic cusp and aneurysmal sac. This process gradually reduces the size of the VSD until even an anatomically large defect becomes functionally small. Pulmonary arterial hypertension and increased pulmonary vascular resistance therefore are rare. By the time most patients with this combination of anomalies reach age 15 to 20 years, a fixed fibrous deformity of the prolapsed cusp has developed.

Technique Of Operation

The many types and variations of ruptured and unruptured sinus of Valsalva aneurysms, as well as the rarity of some, make detailed description of repair of each impractical. Instead, this section details repair of three of the most common varieties; from these, the techniques of repair for most other aneurysms can be deduced. For example, an aneurysm of the right sinus of Valsalva, without VSD, that has ruptured into the right ventricle is repaired much the same as described for this type of aneurysm that has ruptured into the right atrium, but substituting “ventricle” for “atrium.” Some rare and difficult types may be most simply repaired through an aortic approach, closing the origin of the aneurysm from the sinus with a patch.

Unruptured sinus of Valsalva aneurysms are probably best repaired by excision or, occasionally, by exclusion of the aneurysm and reconstruction by the identical method used for a similar but ruptured aneurysm.

Ruptured Right Sinus of Valsalva Aneurysm, with Ventricular Septal Defect

Repair of a ruptured aneurysm at the midportion of the right sinus of Valsalva with coexisting juxta-aortic VSD is described first because the surgical principles are more easily appreciated in this setting. If the aneurysm is in the rightward portion of the right sinus, the VSD is probably conoventricular (perimembranous) and would be approached through the right atrium, often with detachment of the anterior and septal leaflets of the tricuspid valve. If the aneurysm is in the leftward portion of the right sinus of Valsalva, the associated VSD in the infundibular septum would be juxta-arterial, and the approach would be through the right ventricle or pulmonary trunk. In either case, operation is usually facilitated by a combined aortic and right ventricular, pulmonary trunk, or right atrial approach.

Initial preparations follow the usual routine (see Section III of Chapter 2 ). After median sternotomy, the pericardium is opened and complete external evaluation of the heart is made. The protruding nipple of the ruptured aneurysm may be palpated through the free wall of the right ventricle. It is important to note that no external evidence of the aneurysm itself is usually seen, and the aortic root appears to be normal on inspection. Intraoperative transesophageal echocardiography (TEE) is useful for defining the location of the aneurysm and the cardiac chamber into which it has ruptured (see Fig. 36-9 ), and for assessing completeness of the fistula and VSD repair and severity of AR before and after repair.

CPB is established after ascending aorta and direct caval cannulation, and body temperature is reduced. The aorta is clamped promptly, caval tapes are placed and secured, the right atrium is opened through a short oblique incision, and a sump suction catheter is placed across the foramen ovale. In most cases the aortic valve is at least mildly regurgitant. The aortic root is opened transversely ( Fig. 36-10, A ), and cold cardioplegic solution is infused directly into the left and right coronary ostia or retrogradely through the coronary sinus, which is cannulated directly through the opened right atrium (see Chapter 3 ).

Exposure is obtained by placing stay sutures on the edges of the aortotomy. The orifice of the aneurysm is visualized, and elevating the right aortic cusp reveals the underlying VSD. No attempt is made to determine the feasibility of repairing the VSD through the aortic root; it may be difficult through the aortotomy to distinguish between a conoventricular VSD adjacent to the His bundle and a juxta-aortic VSD in the right ventricular outflow tract that does not border the His bundle. Any redundancy or tendency of the right coronary cusp to prolapse is noted, but its repair is deferred.

The right ventricle is opened through a transverse or vertical incision, depending on distribution of the branches of the right coronary artery. Alternatively, an approach is made through the pulmonary trunk. The anatomy is visualized ( Fig. 36-10, B ). The thinned-out windsock, often containing one or more perforations, is resected, creating a large defect in the right sinus of Valsalva. This defect is downstream (cephalad) from the VSD and separated from it by the hinge line of the right aortic cusp ( Fig. 36-10, C ). Most of the excised windsock is devoid of aortic media (see Fig. 36-1 ). A polyester or pericardial patch is sewn into place to close the VSD and the defect in the sinus of Valsalva, and the area of the hinge line of the right aortic cusp, which has been isolated by the resection, is sutured to the patch at an appropriate level ( Fig. 36-10, D-F ).

After closing the ventriculotomy (or pulmonary trunk) with polypropylene suture placed as a continuous stitch, the interior of the aortic root is again exposed through the aortotomy. When AR coexists and the patient is young with pathology limited to prolapse, all or part of a Trusler repair of the aortic valve is then performed (see Chapter 35 , Fig. 35-37, Fig. 35-38 ). In older patients with AR or when the aortic valve defect is more extensive, valve replacement is necessary (see “Cold Cardioplegia, Controlled Aortic Root Reperfusion, and [When Needed] Warm Cardioplegic Induction” in Chapter 12 ). Either before or after closing the aortic root, the controlled, initially hyperkalemic reperfusion is begun if indicated (see Chapter 3 ), the sump suction catheter is removed, and the foramen ovale and then the right atrium are closed. The remainder of the operation is completed in the usual manner (see Section III of Chapter 2 ). Alternatively, when it is certain that the VSD is not conoventricular, the entire repair can be performed through the aortic root. Attachment of the base of the right coronary cusp to the patch is more conveniently accomplished from this exposure than from the right ventricular approach.

Unruptured Sinus of Valsalva Aneurysm

Most unruptured sinus of Valsalva aneurysms can be repaired through the ascending aorta. CPB is established using a single cannula in the right atrium (see Section III of Chapter 2 ). A venting catheter is placed into the left atrium through the right superior pulmonary vein. A catheter is placed into the ascending aorta for delivery of cardioplegic solution; alternatively, a cannula can be placed into the coronary sinus for delivery of cardioplegic solution retrogradely. The ascending aorta is occluded and cardioplegic solution administered. The aorta is opened transversely and the site of origin of the aneurysm identified ( Fig. 36-11, A-B ). The orifice of the aneurysm is closed with a polyester or pericardial patch, avoiding injury to the aortic cusp and ostium of the coronary artery ( Fig. 36-11, C ). If the aneurysm is large with associated AR, valve replacement, aortic root replacement with a composite valve-graft or aortic allograft, or a valve-sparing procedure may be necessary.

Special Features Of Postoperative Care

The usual care is given to patients after repair of sinus of Valsalva aneurysm (see Chapter 5 ).

Results