Congenital aneurysms of the sinuses of valsalva

Anatomic considerations

Aneurysms of the sinuses of Valsalva account for 1% of congenital anomalies of the heart and circulation. The aneurysms tend to be single, although exceptionally, more than one sinus is involved. ^, An aneurysm may arise from each sinus of a bicuspid aortic valve, ^, from each sinus of a trileaflet aortic valve, and rarely, from a quadricuspid aortic valve.

The anatomic relationship of the sinuses of Valsalva to adjacent structures determines the site into which a given congenital aneurysm ruptures. Ninety to ninety-five percent originate in the right or noncoronary sinus and project into the right ventricle or right atrium , and less than 5% originate in the left coronary sinus ( Fig. 20.2 ). ^{, ,} Those arising in the noncoronary sinus almost always rupture into the right atrium ( Fig. 20.3 and Video 20.1 ; see also Fig. 20.2 ), and those arising in the right coronary sinus rupture into the right ventricle or occasionally into the right atrium ( Figs. 20.4 and 20.5 , and Videos 20.2 and 20.3 ; see also Fig. 20.2 ). Rarely, rupture is into the pulmonary artery, ^, left ventricle, left atrium, or pericardial space. ^, Also rarely, a sinus aneurysm dissects into the interventricular septum where it remains unruptured, or perforates and ruptures into the left or right ventricle. ^, A congenital etiology is questionable when an aneurysm originates in the left coronary sinus and ruptures into the left side of heart.

A sinus of Valsalva aneurysm can cause aortic regurgitation by interfering with aortic leaflet coaptation, can enter the right atrium and cause tricuspid regurgitation , or can enter the right ventricular outflow tract and cause subpulmonary obstruction. A congenital aortic sinus aneurysm that is the site of infective endocarditis can be difficult to distinguish from aortic valve infective endocarditis that caused the aortic sinus to perforate. ^, A large unruptured aneurysm can compress the superior vena cava, the right atrium, the right ventricle, or a coronary artery.

A congenital sinus of Valsalva aneurysm begins as a blind pouch or diverticulum at a localized site in an aortic sinus, and then protrudes as a finger-like or nipple-like projection that ruptures at its tip (see Figs. 20.2 , 20.3 , and 20.5 ; see also Videos 20.1 and 20.2 ). ^{, ,} The fundamental histologic fault responsible for a coronary sinus aneurysm is discontinuity of the elastic layer in the aortic media at the juncture between the ascending aorta and aortic valve annulus, setting the stage for avulsion and aneurysm formation. ^, The histologic fault is present at birth, but with rare exception, the aneurysm is not. ^{, ,} Marfan syndrome is associated with dilation of the ascending aorta and the sinuses of Valsalva, but dissection or rupture is in the ascending aorta, not in the sinuses. Dilation of the sinus of Valsalva may also occur in patients with bicuspid aortic valve, more commonly in males and patients with typical bicuspid aortic valve morphology. An aortico-cameral communication is a tortuous channel that originates in the ascending aorta above the left sinus of Valsalva and terminates in the right atrium without involving the aortic sinuses.

Physiologic consequences

The physiologic consequences of rupture depend on three factors: (1) the amount of blood flowing through the rupture, (2) the rapidity with which the rupture develops, and (3) the chamber that receives the rupture. Irrespective of the right-sided receiving site, shunted blood must flow through the pulmonary circulation, the left atrium, and the left ventricle before returning to the aorta. When the right atrium receives the rupture, all four cardiac chambers are volume overloaded. A sudden large rupture provokes congestive failure because the heart cannot adapt rapidly to the acute hemodynamic burden. Conversely, small insidious perforations initially go unnoticed ( Fig. 20.6 ). Deformity of aortic cusps caused by a ruptured or unruptured aneurysm causes regurgitation through the valve , while rupture of a sinus aneurysm into the left ventricle causes regurgitation through the rupture . Aneurysms that originate in the right sinus of Valsalva are typically associated with a supracristal ventricular septal defect (see Fig. 20.2 ). ^{, ,}

Unruptured congenital sinus of Valsalva aneurysms were recognized by Thurnam (see earlier). Before the advent of echocardiography, approximately 20% of unruptured aneurysms were chance findings at necropsy or at cardiac surgery. However, occult unruptured congenital aortic sinus aneurysms are now readily imaged, even in older adults ( Fig. 20.7 ). ^, An unruptured aneurysm can compress a proximal coronary artery or can dissect into the ventricular septum and cause complete heart block. Protrusion of an aneurysm into the left ventricle is occasionally responsible for aortic regurgitation (see earlier) less commonly for obstruction to left ventricular outflow.