We report the case of a 79-year-old woman with a history of methicillin-resistant Staphylococcus aureus bacteremia and purulent pericarditis with subsequent subxiphoid pericardiostomy and formation of a large left ventricular pseudoaneurysm (LVPA) that has been medically managed. Long-term survival after pseudoaneurysm formation has traditionally been thought to be unusual without operative intervention. Computed tomography (CT), three-dimensional reconstructed CT, and echocardiographic images documenting the progression of the LVPA are presented over the course of the patient’s follow-up. This case highlights the natural history of LVPA and the utility of multimodal imaging in allowing accurate assessment of LVPA anatomy.
Case Report
A 79-year-old white woman presented with dyspnea and pleuritic chest pain. Her examination was notable for diminished breath sounds and dullness to percussion bilaterally, and a soft systolic murmur at the apex. Electrocardiography showed a normal sinus rhythm with a leftward axis, poor R-wave progression, and nonspecific T-wave abnormality. Laboratory results were remarkable for pancytopenia and an elevated D-dimer. A chest CT to rule out pulmonary embolus revealed a 2.5 × 3.6-cm LVPA ( Figure 1 ). An echocardiogram demonstrated a large cavity with bidirectional flow along the posterior wall of the left ventricle (LV), just beneath the mitral valve annulus ( Figure 2 B). Two months earlier the patient was hospitalized for methicillin-resistant S. aureus bacteremia and purulent pericarditis that was treated with a subxiphoid pericardiostomy and antibiotics. One month after that admission (1 month before the index admission), she was diagnosed with myelodysplastic syndrome deemed independent of her antibiotic therapy; an echocardiogram ( Figure 2 A) and chest CT at that time were unremarkable.
The patient and family declined surgery. During the ensuing year, the patient has done relatively well with transfusions and close follow-up. As depicted in Figure 2 B-D, the pseudoaneurysm continued to expand briskly at first, then appeared to plateau. Except for episodes of atrial arrhythmias and mild volume overload, the patient has been free of cardiac symptoms.
Discussion
LVPAs result from cardiac rupture contained by organizing thrombus and pericardium, and are characterized by the nature of their walls, narrow necks, and high risk of rupture. In contrast, true LV aneurysms have walls of myocardium, wide necks, and low risk of rupture. LVPAs most frequently form after transmural myocardial infarction but may result from cardiac surgery, trauma, infections, inflammation, or structural defects; it is possible that this patient’s LVPA may have been caused by purulent myopericarditis or unrecognized endocarditis (as the result of the proximity to the posterior mitral leaflet). The risk of rupture is hypothesized to be associated with increased LV pressure and pseudoaneurysm diameter (and resulting wall stress), as well as compromised myocardial integrity, as in myocardial infarction.
Heart failure, chest pain, and dyspnea are the most frequently reported symptoms, although pseudoaneurysms are frequently asymptomatic or present with nonspecific symptoms. Physical examination may reveal a systolic or to-and-fro murmur secondary to turbulent flow across the narrow neck. Mild mitral regurgitation was present initially, but significant flow across the pseudoaneurysm developed ( Figure 3 , [CR] ). Visualization of LVPA may be accomplished by a variety of methods, including transthoracic and transesophageal echocardiography, magnetic resonance imaging, CT, and LV angiography. A real-time three-dimensional transthoracic study ( [CR] ) of the LVPA neck demonstrated the dynamic nature of the rupture orifice area en face. Although echocardiography remains the basis of imaging, given its relatively low cost, reproducibility, ease of performance, lack of iodinated contrast, versatility, and noninvasive nature, there is value in a contrasted CT scan that may yield important additional information. As in this case, the left circumflex artery traversed across the aneurysmal sac, which is key for proper surgical planning ( Figure 4 ) had the patient been an operative candidate.
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