Acute aortic dissection flap prolapsing into the left ventricle on transthoracic echocardiography.

Abstract

A 62-year-old man with a history only of untreated hypertension presented with acute onset right buttock pain and leg weakness. He had neither significant chest pain nor initial hemodynamic disturbance (BP 106/28, pulse 55). Examination revealed marked weakness of the right leg with absence of palpable pulses. An ECG unexpectedly showed widespread ischemia. A transthoracic echocardiogram (TTE) was performed. There was no parasternal window, but in the apical four-, five-chamber and subcostal five-chamber views a large flap of aortic intima, with a hinge point immediately distal to the aortic valve (AV), was seen prolapsing through the AV during diastole (Fig. 1a) associated with severe aortic regurgitation (Fig. 1b). The flap prolapsed into the left ventricle in diastole (Fig. 1c) and returned to its original position during systole, partially closing the dissection orifice (Fig. 1d and supplementary video). Aside from mild anterior hypokinesis, left ventricular size and systolic function appeared normal. There was no significant pericardial effusion. The diagnosis of type A aortic dissection (AD), extending from the aortic root to iliac vessels and involving most major branches, was confirmed on contrast computed tomogram. The patient unfortunately died in the intensive care unit shortly afterward before surgery could be undertaken. Isolated leg pain and weakness as the presenting features of AD occur in less than 4 % of cases [1]. TTE is a portable, easily accessible tool that can be used in the initial investigation of suspected AD but is often overlooked. The sensitivity for detecting AD is reported as being between 59 and 83 % (highest in type A dissection) and specificity between 63 and 93 % with reverberation artifacts from either the walls of the left atrium or the pulmonary artery accounting for much of the potential for false-positive TTE studies [2]. In addition to the ability to identify a dissection flap, and thus provide a definitive diagnosis, TTE is also useful to identify complications such as aortic regurgitation, aortic root dilatation and pericardial effusion. TTE can also differentiate AD from myocardial infarction in the acutely unwell patient with chest pain where the presence or absence of left ventricular regional wall motion abnormalities is invaluable [3]. Prolapse of an aortic dissection flap into the ventricle is rare, although one report using TEE suggested a prevalence as high as 15 % in ADs involving the ascending aorta. Previous reports in the literature are scant [4–6]. Mechanistically a large flap of aortic intima, anchored proximally, moves to and fro with pulsatile blood flow. Complications may occur because of the extent and propagation of the false lumen, the acute left ventricular hemodynamic changes due to severe acute aortic regurgitation or direct coronary ostial obstruction during diastole by the dissection flap. The appearance of the prolapsing intimal flap on TTE is highly unusual and infrequently reported, and accurate identification may be difficult, particularly if imaging windows are suboptimal. In this case, despite the absence of a parasternal window, a modified subcostal Electronic supplementary material The online version of this article (doi:10.1007/s12574-012-0143-z) contains supplementary material, which is available to authorized users.