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Transcatheter Closure of Cardiac Pseudoaneurysms
Left ventricular (LV) pseudoaneurysm is a rare but serious complication of myocardial infarction (MI), cardiac surgery, trauma, and infection. Medical treatment alone is frequently not effective and is associated with as much as 50% mortality. Until recently, the recommended treatment was surgical closure. These surgeries carried high risk because of abnormal hemodynamics, necrotic substrates, and the comorbidities of these patients. Recently, transcatheter closure has been shown to be an acceptable alternative to open surgical intervention. Multimodality imaging, including three-dimensional (3D) echocardiography, identifies the location, size, and shape of the defect and can assess, guide, and follow up the closure procedure. This chapter discusses the use of transcatheter procedures in the treatment of an important complication of acute MI, namely LV pseudoaneurysm. Medical treatment of these patients carries very poor outcomes with high mortality rates. Surgery can close the defect but still involves high mortality rates. Transcatheter closure of these conditions is feasible and may be an effective alternative therapy in those patients with hemodynamic instability and other comorbidities. Real-time 3D echocardiography is an important imaging modality in the diagnosis and the assessment of this structural heart disease and has a significant role in guiding and monitoring the interventional procedure.
Pathophysiology of Left Ventricular Pseudoaneurysm
LV free wall rupture is the most common acute tear of the left ventricle in patients with acute MI. Unfortunately, acute free wall tear leads to severe intrapericardial bleeding in most patients, which rapidly results in cardiac tamponade and death. Accordingly, free wall tear accounts for 14% to 20% of all MI-related deaths. In contrast, it is seen in only 7% of all in-hospital MI-related deaths. In other words, most cases of death from acute free wall rupture occur before arrival in the hospital.
On rare occasions, the rupture is contained by pericardial and fibrous tissue, creating a LV pseudoaneurysm. Characteristically, the orifice of the pseudoaneurysm is narrow, with a characteristic to-and-fro blood flow: from the left ventricle into the pseudoaneurysm during systole and from the pseudoaneurysm into the left ventricle during diastole. The pseudoaneurysm wall is made of adherent pericardial or fibrous tissue, without any myocardial or endocardial layers. Thus, the wall is thin and may easily rupture and cause bleeding into the chest cavity and death.
A meta-analysis reviewed the charts and reports of 290 patients with LV pseudoaneurysms. It demonstrated that approximately two-thirds of all LV pseudoaneurysms occur after MI. Pseudoaneurysms are more common in men (75%) and in whites (75%), and the average age of these patients is 60 years. The presenting symptoms in infarct-related pseudoaneurysm included congestive heart failure in 36%, chest pain in 30%, shortness of breath in 25%, and sudden death in 3%. Twelve percent were asymptomatic at the time of presentation.
In this meta-analysis, the maximal diameter of the pseudoaneurysm varied from 1.5 to 20 cm. The pseudoaneurysm involved the posterior and lateral walls more commonly than the anterior wall. It appears that the risk of rupture is higher in the first 3 months after infarction. Later, pseudoaneurysms become chronic and stable and may remain intact for years.
Besides rupture, which may result in bleeding, exsanguination, and cardiac tamponade, other complications include heart failure, arrhythmia, clot formation and embolization, and compression of coronary arteries, which may result in ischemia and compression of extracardiac structures. Pseudoaneurysms can also occur after mitral valve replacement, with a rupture near the posterior aspect of the mitral ring. Other conditions that may lead to LV pseudoaneurysm formation include aortic valve replacement, endocarditis with abscess formation, and penetrating cardiac trauma. Several recent case reports have described apical LV pseudoaneurysm after transcatheter aortic valve implantation.
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