Portal de Periódicos da CAPES

Transesophageal Echocardiography of a Unicuspid Aortic Valve

2009; Lippincott Williams & Wilkins; Volume: 108; Issue: 3 Linguagem: Inglês

10.1213/ane.0b013e318193cbd8

1526-7598

Roman M. Sniecinski, Jack S. Shanewise, Kathryn E. Glas,

Infective Endocarditis Diagnosis and Management

A 34-yr-old man complaining of increasing shortness of breath was diagnosed by transthoracic echocardiography with severe aortic regurgitation and concomitant mild aortic stenosis. He had no history or visualized cardiac masses to suggest endocarditis and it was believed that his valvular disease was due to a congenitally bicuspid aortic valve. Because of the severity of his symptoms, he was taken to the operating room for aortic valve replacement (AVR). Intraoperative transesophageal echocardiography (TEE) confirmed the presence of severe regurgitation through an aortic valve that appeared thickened and calcified (Video 1; please see video clip available at www.anesthesia-analgesia.org). There was also a component of stenosis, with a peak gradient of 32 mm Hg measured by spectral Doppler. The left ventricle had normal function, measured 5.2 cm at end-diastole, and was slightly hypertrophied with an end-diastolic thickness of 1.3 cm. The aortic annulus measured 24 mm, the sinotubular junction was 25 mm, and the proximal aorta was 38 mm in diameter. Close inspection of the aortic valve in short axis, however, did not reveal the typical elliptical opening of a bicuspid valve. Instead, there appeared to be one eccentric orifice with a single commissure on the posterior aspect of the aortic annulus (Fig. 1 and Video 2; please see video clip available at www.anesthesia-analgesia.org). Surgical inspection after aortotomy confirmed that this was a unicuspid aortic valve. Replacement with a bileaflet mechanical valve proceeded uneventfully. The patient made a full recovery and was discharged home on postoperative day 4.Figure 1.: This is a mid-esophageal short axis view of the aortic valve during diastole (A) and systole (B). In (A) the arrows point to what looks like three commissures. The coaptation defect causing regurgitation is apparent. In (B) the arrow points to the lateral attachment of the cusp to the aorta, creating a true commissure and a "teardrop" opening. Note that the left main coronary ostium is seen in its usual position of about 3 o'clock.A unicuspid aortic valve is an extremely rare condition, with an estimated incidence of 0.02% in the adult echocardiography population,1 and accounting for ≤5% of patients presenting for isolated AVR.2 It is a congenital malformation that results from abnormal valvulogenesis. Normally, three cusps with associated commissures develop from embryonic tubercles of the aortic trunk. In a bicuspid aortic valve, commissural development is aborted in one of the tubercles, resulting in a thick ridge, or raphe, where the commissure should have been. Similarly, a unicuspid valve usually results from the failure of two commissures to develop. During diastole, the raphae often look like true commissures in the TEE short axis view, making it easy to mistake the valve for being tricuspid. During systole, however, there is no cusp separation, leading to an elliptical "fish-mouth" opening in a bicuspid valve and an eccentric "teardrop" opening in a unicuspid valve. Rarely, an extra commissure develops during valvulogenesis, resulting in a quadricuspid aortic valve. This anomaly is best identified during diastole, where the short axis view resembles an "X."3 It should be noted that the Sinuses of Valsalva also originate from the embryonic tubercles, but their development is usually normal. Consequently, coronary arteries are generally in the normal position in patients with a unicuspid valve (Fig. 1). There are two recognized types of unicuspid aortic valves, unicommissural and acommissural, based upon whether or not there is a lateral attachment to the aorta at the level of the orifice (Fig. 2).4 Our patient had a unicommissural valve, which is thought to be the more common of the two. In this configuration, there is one lateral attachment to the aorta and the single cusp wraps around the aortic orifice, back to the point of origin without further attachments. In our case, the true commissure occurred posteriorly, at about 12 o'clock, although this attachment point is variable among different patients. An acommissural type unicuspid aortic valve has a more centralized, triangular opening caused by under-development of all three cusps. The cause is likely the aborted commissural development in all three tubercles, resulting in three raphae, and no commissures or lateral attachments to the aorta. The stenosis of an acommissural valve is quite severe and usually diagnosed in infancy.Figure 2.: This is a schematic diagram illustrating the difference between a unicommissural type valve (A) and an acommissural type valve (B). Note that (A) has a lateral attachment of the valve orifice to the aorta, creating one true commissure. (B) lacks this attachment and has only a central orifice and three raphae, represented by dashed lines in both (A) and (B).Whatever the morphology, malformation of the aortic valve leaflets causes an increased rate of calcification and fibrosis of the valve, progressing toward significant stenosis and/or regurgitation. As a general rule, fewer valve cusps result in earlier need for valve replacement.2 Unicuspid valves, like bicuspid valves, may also be associated with dilation of the ascending aorta. In one surgical series, half of patients with a unicuspid valve presenting for AVR had ascending aortas measuring >40 mm, and underwent aortic replacement as well.5 Because our patient had only minimal dilation, we elected to defer replacement and monitor possible progression. In their published series in 1971 on unicuspid valves, Falcone et al.4 remarked that "it is apparently impossible to determine before operation or autopsy the presence of a stenotic unicommissural unicuspid aortic valve in an adult." Today, as our case illustrates, the diagnosis of aortic valve malformations is not only possible with TEE, but actually commonplace. The echosonographer simply needs to be aware of what to look for.