Discussion:
Over its clinical course, IE can destroy large areas of tissue in the
aortic annulus, reducing the strength and stability of native cardiac
tissue while simultaneously increasing the risk of LV-Ao discontinuity.
Extensive debridement of infected cardiac structures prior to valve
replacement further adds to risk of discontinuity because it decreases
the amount of available healthy tissue available for restructuring and
repair of the LVOT.3 The avascular nature of the
mitral aortic intervalvular fibrosa (MAIVF) in the LVOT makes it
susceptible to infection and abscess formation in the setting of aortic
valve and root endocarditis. Aortic valve regurgitation in the setting
of aortic valve endocarditis may also contribute to MAIVF pseudoaneurysm
formation, as the infected regurgitation jets hit the inherently
susceptible MAIVF. In the setting of IE, Staphylococcus species are the
most implicated cause of abscess and pseudoaneurysm
formation.4 After surgical correction, follow up by
TTE can assess prosthetic valve function but may be insufficient to
diagnose new abscesses or pseudoaneurysms. In such cases, other imaging
modalities, such as ECG-gated CT or magnetic resonance imaging, can
improve sensitivity and accuracy in diagnosis of these complications. As
LVOT pseudoaneurysms and complete discontinuity may present with
nonspecific signs and symptoms such as heart failure and chest pain,
advanced cross section imaging should be considered
early.5,6 LVOT pseudoaneurysms carry high risk of
rupture and subsequent sudden cardiac death with a frequency of up to
50%. TTE has been shown to be an ineffective modality for diagnosing
LVOT pseudoaneurysm and discontinuity.4,5,7,8 In a
previously published review, definitive diagnoses by TTE were achieved
only in 36% of cases and missed up to 65% of the
time.4 Transesophageal echocardiography can increase
the sensitivity and specificity for diagnoses of such lesions. Cardiac
computed tomography, as exemplified in this case, provides higher
sensitivity than TTE and better 3-dimensional assessment of the
lesion.4,5