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From the Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, Charleston, South Carolina.
A 75-yr-old man with a history of a five vessel coronary artery bypass graft surgery (CABG) 8 yr prior presented to the hospital emergency department with acute onset chest pain. A 12-lead electrocardiogram was performed, which demonstrated a transmural Q wave myocardial infarction. Cardiac enzymes were consistent with this finding. The patient was stabilized and underwent cardiac catheterization with ventriculography, which demonstrated closure of the circumflex vein grafts and a contained rupture of his left ventricle (LV). He was taken to the operating room for LV repair. Exposure was through a left thoracotomy in the right lateral decubitus position and aortofemoral cannulation was used for bypass. A complete intraoperative transesophageal echocardiography examination was performed (Figs. 1 and 2, see video clips 1 and 2 available at www.anesthesia-analgesia.com), which identified an inferolateral wall pseudoaneurysm of the LV. The pseudoaneurysm had undergone distal extension into the pericardial space. Because of the patient's previous CABG surgery, pericardial adhesions prevented exsanguination and tamponade (Fig. 3 demonstrates this loculated pericardial clot). A 2 cm x 3 cm defect in the inferolateral wall of the LV was resected and repaired. The patient was separated from cardiopulmonary bypass and transferred to the cardiac intensive care unit in stable condition. He had an uneventful postoperative course and was discharged home 4 days postoperatively.
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DISCUSSION
As in this case, postmyocardial infarction LV pseudoaneurysms occur when the LV rupture is contained by the pericardium. Because the inferolateral wall has an isolated blood supply from the left circumflex coronary artery, it is the most frequent location for a pseudoaneurysm. The ability to distinguish a true aneurysm from a pseudoaneurysm often provides a challenge for the echocardiographer. The two-dimensional characteristics of a true aneurysm versus a pseudoaneurysm are summarized in Table 1. Quantitatively, measurements comparing the ratio of the maximal internal orifice width (neck diameter) and the maximal parallel internal diameter of the aneurysm must be performed. Pseudoaneurysms present with a ratio 
0.5, whereas true aneurysms are >0.9 (1,2). Hence, pseudoaneurysms are described as having narrow neck orifices versus the wide neck orifices, which are typical of true aneurysms. The ratio in this particular case was determined to be 0.24.
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Pseudoaneuryms may be difficult to diagnose with transthoracic echocardiography imaging, where the narrow neck can be poorly visualized. The improved two-dimensional resolution of transesophageal echocardiography usually makes the diagnosis obvious. Turbulent flow patterns at the neck of the defect, as determined by color and pulsed wave Doppler, are suggestive of a pseudoaneurysm and are critical when using transthoracic echocardiography imaging to make the diagnosis. In addition, color flow Doppler provides a qualitative measure to detect bidirectional flow through the neck of the pseudoaneurysm. Flow patterns demonstrate flow from the LV into the pseudoaneurysm during systole, and the reverse is seen during diastole (3). As previously discussed, flow is typically turbulent through the narrow neck orifice in a pseudoaneurysm and more laminar through the wide neck orifice of a true aneurysm (4). Finally, pseudoaneurysms may be detected by opacification of the LV cavity after an echocardiography contrast injection, which will often enable direct visualization of blood entering the pseudoaneurysmal cavity (5).
The transgastric mid short-axis view allowed direct visualization of the communication between the pseudoaneurysm and pericardial space in this particular case. However, nonconventional views may often need to be obtained to correctly identify the defect in the ventricular wall. The unique characteristic of this case is that the pericardial adhesions from the patient's prior CABG served to limit free extension to within the pericardium, and hence prevented acute exsanguinations and the development of cardiac tamponade.
Footnotes
Accepted for publication March 19, 2007.
Address for correspondence and reprint requests to Scott T. Reeves, MD, Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, 165 Ashley Ave. #525, Charleston, SC 29425. Address e-mail to reevess{at}musc.edu.
This article has supplementary material on the Web site: www.anesthesia-analgesia.org.
REFERENCES
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