A 72-year-old man was transferred from an outside hospital after a cardiac catheterization revealed total occlusion of his right coronary artery, an inferior wall aneurysm, and a ventricular septal defect (VSD) 3 weeks after a myocardial infarction. Emergent coronary revascularization and VSD repair were planned. Informed consent for this presentation was obtained from the patient.
Intraoperative transesophageal echocardiography (TEE) revealed a mildly dilated left ventricle (LV), with basal inferolateral, inferior, and inferoseptal akinesis (Video 1, loop 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A160; see Appendix for video legend). In transgastric (TG) midpapillary short-axis view, a large aneurysmal cavity broadly connected to the inferior wall medial to the posteromedial papillary muscle was identified (Video 1, loop 2, http://links.lww.com/AA/A160). In TG mid short-axis and deep TG long-axis views, the walls of the aneurysmal sac were seen comprising connective tissue and lined with thrombotic material (Figs. 1 and 2) (Video 1, loops 2, 3, and 4; http://links.lww.com/AA/A160). Echographically, the thrombotic material appeared well circumscribed, homogeneously soft, with irregular borders and multiple mobile fibrillary projections into the aneurysmal cavity, markedly distinct from the LV myocardium and from the highly echo-reflective pericardium. Blood flow between the LV and the aneurysmal cavity appeared laminar based on color Doppler study (Video 1, loop 5, http://links.lww.com/AA/A160). Upon further examination in the deep TG view, this aneurysm appeared to communicate with the right ventricle through a defect in the inferior septum (Video 1, loop 6, http://links.lww.com/AA/A160); pulse-wave and color Doppler examination confirmed left-to-right systolic flow through this defect (Fig. 3) (Video 1, loop 7, http://links.lww.com/AA/A160). These data were communicated to the surgical team.
Upon entry into the mediastinum, extensive dense pericarditis was noted, and a large LV inferior wall pseudoaneurysm, contained by the adherent pericardium and communicating with the right ventricle through the postinfarct VSD, was identified. The patient underwent coronary revascularization and closure of the defects in the interventricular septum and LV inferior wall with bovine pericardium and BioGlue® Surgical Adhesive (CryoLife Inc., Kennesaw, GA). He made an uneventful recovery and was discharged in satisfactory condition.
Myocardial infarction can result in rupture of a free LV wall in 4% of patients.1 Overlying adherent pericardium may contain the defect, giving rise to a false (pseudo) aneurysm. Lacking the structural support of myocardium, an LV pseudoaneurysm carries a significant risk of expansion and fatal rupture.2 This entity needs to be differentiated from a true LV aneurysm, arising in an area of a thinned or scarred myocardium. Both true and false LV aneurysms may result in heart failure, thromboembolic events, and ventricular arrhythmias secondary to sluggish blood flow in a noncontractile aneurysmal cavity and disrupted ventricular conduction. Distinguishing between true and false LV aneurysms is essential in determining the appropriate therapeutic approach and prognosis. Pseudoaneurysms specifically require urgent surgical intervention.2
The most important fundamental feature differentiating true and false aneurysms is the presence of a continuous surrounding myocardial wall in the former, and its absence in the latter.1 Demonstration of myocardial wall discontinuity may be confounded by the presence of thrombotic material lining the adherent pericardium. Pseudoaneurysmal wall composition (pericardium with mural thrombus) should be carefully distinguished from a true aneurysm's myocardium. Analysis is greatly facilitated by the use of appropriately focused zoomed images of the aneurysmal neck and sack walls.
Only if myocardial continuity and aneurysmal wall composition are uncertain should secondary characteristics be used. Traditionally, an LV pseudoaneurysm is described as a globular, echo-free cavity connected to the ventricular chamber via a relatively narrow orifice (neck), with a ratio of the maximum neck diameter to the maximum aneurysm diameter (Gatewood and Nanda index) <0.5. Turbulent blood flow through the neck or within the cavity is another secondary characteristic of pseudoaneurysms.3,4 Conversely, true LV aneurysms are usually characterized by laminar flow through a mouth as wide as or wider than their internal diameter. Significantly, these surrogate criteria may not be universally applicable, because pseudoaneurysms resulting from inferior wall myocardial infarctions (posterior descending artery distribution in our case) are characteristically observed to have wider necks (Gatewood and Nanda index of >0.5) than those resulting from apical infarctions (left anterior descending artery distribution).5 Another confounding aspect stems from the presence of mural thrombi. Blood pool imaging (as an echo-free space or by scintigraphy and contrast ventriculography) may underestimate the neck diameter if it is lined with thrombotic material.1 Consequentially, echocardiography (TEE more accurately than transthoracic for posterior wall aneurysms) has replaced contrast ventriculography as the diagnostic standard; its portability is an advantage over highly accurate magnetic resonance imaging.2
Therefore, characteristics such as a narrow neck with a saccular or globular chamber, ratio of the maximum neck diameter to the maximum aneurysm diameter, and turbulent blood flow through the aneurysmal neck, tabulated in an Echo Rounds,3 have limited application and may be misleading if the composition of the aneurysmal wall is not examined carefully. Thus, in our patient, the correct diagnosis of a pseudoaneurysm was established by the demonstrated myocardial discontinuity in the sac wall, itself composed of adherent pericardium with mural thrombus lining. This diagnosis was reached despite surrogate characteristics suggestive of a true aneurysm, namely, a Gatewood and Nanda index of approximately 0.7 and laminar flow to-and-fro the aneurysm.
In conclusion, we present and discuss the TEE images of a surgically confirmed inferior wall pseudoaneurysm that exhibited echocardiographic criteria classically attributable to true aneurysms.
1. Brown SL, Gropler RJ, Harris KM. Distinguishing left ventricular aneurysm from pseudoaneurysm: a review of the literature. Chest 1997;111:1403–9
2. Atik FA, Navia JL, Vega PR, Gonzales-Stawinski GV, Alster JM, Gillinov AM, Svensson LG, Pettersson BG, Lytle BW, Blackstone EH. Surgical treatment of postinfarction left ventricular pseudoaneurysm. Ann Thorac Surg 2007;83:526–31
3. May BV, Reeves ST. Contained rupture of a left ventricular pseudoaneurysm. Anesth Analg 2007;105:38–9
4. Gatewood RP, Nanda NC. Differentiation of left ventricular pseudoaneurysm from true aneurysm with two dimensional echocardiography. Am J Cardiol 1980;46:869–78
5. Hung MJ, Cherng WJ, Kuo LT, Wang CH. Echocardiographic characteristics of patients surviving nonsurgically treated left ventricular pseudoaneurysm after acute myocardial infarction. Am J Cardiol 2003;91:328–31
APPENDIX: VIDEO LEGENDS
Loop 1. Transgastric basal short-axis view of the left ventricle. Inferior and inferoseptal wall segments appear akinetic.
Loop 2. Transgastric midpapillary short-axis view of the left ventricle (LV). A pseudoaneurysmal cavity is seen broadly communicating with the LV. Arrow points to the thrombus-lined pericardium.
Loop 3. Deep transgastric long-axis view. A pseudoaneurysmal cavity is seen medial to the posteromedial papillary muscle, broadly communicating with the left ventricle (LV). Arrows point to the thrombus-lined pericardium. LA, left atrium.
Loop 4. Transgastric 2-chamber view of the left ventricle (LV). An inferior wall pseudoaneurysm is seen broadly communicating with the LV. Arrow points to the thrombus-lined pericardium. LA, left atrium.
Loop 5. Transgastric 2-chamber view of the left ventricle (LV). An inferior wall pseudoaneurysm is seen broadly communicating with the LV. Flow between the LV and pseudoaneurysmal cavity is laminar.
Loop 6. Deep transgastric long-axis view. An inferior wall pseudoaneurysm is seen broadly communicating with the left ventricle (LV). A defect could be appreciated in the inferior interventricular septum, allowing communication between the pseudoaneurysmal cavity and the right ventricle (RV) (left-to-right shunt). LA, left atrium.
Loop 7. Deep transgastric long-axis view. An inferior wall pseudoaneurysm is seen broadly communicating with the left ventricle. A defect could be appreciated in the inferior interventricular septum, allowing communication between the pseudoaneurysmal cavity and the right ventricle, by color Doppler examination.
Clinician's Key Teaching Points By Roman M. Sniecinski, MD, Nikolaos J. Skubas, MD, and Martin J. London, MD
- A ventricular pseudoaneurysm (false aneurysm) is caused by rupture of the ventricular wall, usually from a myocardial infarction. The cavity is contained by fibrosed endocardium and adherent pericardium. Unlike a true aneurysm, which is lined with all myocardial layers, a pseudoaneurysm lacks structural support, is prone to rupture, and usually requires urgent surgical resection.
- Using transesophageal echocardiography, the most common criteria used to distinguish a true ventricular aneurysm from a pseudoaneurysm are: (1) the presence of a continuous layer of myocardium; (2) a large ratio of the diameter of the aneurysmal “neck,” or opening to the ventricle, to the maximum cavity diameter (<0.5 for pseudoaneurysms); and (3) the presence of laminar flow (versus turbulent flow for a pseudoaneurysm) by color flow Doppler into the cavity.
- In this case, an inferiorly located left ventricular pseudoaneurysm was diagnosed by the absence of myocardial layers in its wall, despite having a wide neck with high neck/cavity ratio, and laminar flow into the cavity.
- Pseudoaneurysms can form in either the right or left ventricle and should be distinguished from true ventricular aneurysms because of the need for early treatment. Absence of myocardial layers should be the primary echocardiographic diagnostic criterion for false aneurysm, even if contradictory secondary findings are present.