Anesthesia & Analgesia:
Cardiovascular Anesthesiology: Echo Rounds
A Potential Use for Intraoperative Three-Dimensional Transesophageal Echocardiography in Predicting Left Ventricular Chamber Dimensions and Ejection Fraction After Aneurysm Resection
Azran, Marc S. MD*; Kwong, Raymond MD, MPH†; Chen, Frederick Y. MD, PhD‡; Shernan, Stanton K. MD§
From the *Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia; Department of †Medicine, and ‡Division of Cardiac Surgery, Harvard Medical School, Boston; and §Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
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The authors obtained written informed consent from the patient (subject of this manuscript) to publish this Echo Rounds.
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Address correspondence to Stanton K. Shernan, MD, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, 75 Francis St., Boston, MA 0215. Address e-mail to firstname.lastname@example.org.
Accepted July 27, 2010
Published ahead of print September 22, 2010
A 52-year-old man presented with nausea and shoulder discomfort. His electrocardiogram (ECG) was consistent with a left ventricular (LV) inferior wall myocardial infarction. Cardiac catheterization revealed a right coronary artery occlusion and good collateral flow to the posterior descending artery. He underwent successful placement of 2 overlapping drug-eluting stents in his right coronary artery. A transthoracic echocardiogram (TTE) revealed a LV ejection fraction (EF) of 45% with an aneurysm in the basal to mid-inferior wall.
The patient presented again 3 months later with angina. A TTE revealed worsening LV function with an EF of 35%, and an enlarging 2 × 5 cm inferolateral aneurysm. Cardiac magnetic resonance imaging (CMRI) demonstrated a 7.8 × 6.9 cm LV basal inferior and inferolateral aneurysm, and an EF of 28% with a 424-mL end-diastolic volume (EDV) and a 305-mL end-systolic volume (ESV) (Table 1). He was referred for cardiac surgery to repair the LV aneurysm to improve long-term systolic function.
After uneventful general anesthesia induction, intraoperative transesophageal echocardiography (TEE) using a 3-dimensional matrix-array transducer (3D TEE) was performed before and after repair of the LV aneurysm. Baseline 2D TEE examination revealed a 7.3 × 7.6 cm basal inferolateral aneurysm with a neck-to-diameter ratio of <0.5 and intracavitary spontaneous contrast, but no evidence of mural thrombus (Fig. 1) (see Supplemental Digital Content 1, Video 1, http://links.lww.com/AA/A186; see Appendix for video legend). Mild mitral regurgitation was demonstrated. Subsequently, a 3D full-volume, ECG-gated reconstruction of the LV was acquired to calculate the EF from the EDV and ESV using commercially available software as previously described.1 Specifically, 2D imaging planes of nonforeshortened LV 4-chamber and 2-chamber views were obtained from the 3D data set. Required anatomical landmarks were then manually assigned to the LV base and apex. An additional 6 manually positioned reference points were assigned along the endocardial border of the aneurysm visualized in the 2D views noted above, to permit accurate volume rendering. Automated endocardial border detection and sequence analysis were then initiated to measure 3D LVEDV and LVESV, and to calculate LVEF (Table 1; Fig. 2) (see Supplemental Digital Content 2, Video 2, http://links.lww.com/AA/A187; see Appendix for video legend). The additional 6 aneurysm reference points were then manually reassigned to virtually exclude the aneurysm to predict the estimated postcardiopulmonary bypass (CPB) LVEDV, LVESV, and LVEF immediately after surgery (Table 1; Fig. 3A) (see Supplemental Digital Content 3, Video 3A, http://links.lww.com/AA/A188; see Appendix for video legend). Finally, these virtual estimates were compared with actual measurements obtained similarly from a post-CPB 3D full-volume ECG-gated reconstruction of the LV, after endoventricular patch repair, using only the required anatomical landmarks for automated border detection and sequence analysis (Table 1; Fig. 3B) (Video 3B, http://links.lww.com/AA/A188). A TTE obtained 1 month postoperatively demonstrated a 40% LVEF, similar to the immediate post-CPB 3D echocardiographic measurements.
The majority of true ventricular aneurysms result from ischemic heart disease and transmural myocardial infarction, with resultant myocardial scar formation and ventricular remodeling.2 The incidence of LV aneurysm in this setting is 2% to 6%, a historic decrease attributable to advances in medical management and early revascularization strategies.2 A true LV aneurysm is defined as an area of dyskinesis during systole with abnormal diastolic morphology.2 Systolic dysfunction secondary to ventricular remodeling and scar tissue contribute to symptomatic heart failure and arrhythmias, predictors of increased mortality that serve as indications for surgical intervention.3
Echocardiographic diagnosis of true ventricular aneurysm4 can be confirmed by CMRI documenting the presence of full-thickness myocardium. Intraoperative 2D TEE examination of an LV aneurysm should include a thorough interrogation of the mitral valve, because papillary muscle dysfunction and displacement can produce significant mitral regurgitation secondary to leaflet tethering and restriction—mechanisms that should be brought to the surgeon's attention in contemplation of mitral valve repair or replacement. A low-flow state within the aneurysm, as demonstrated by spontaneous echo contrast, may create optimal conditions for mural thrombus formation. Because one-fifth of these patients with mural thrombus develop thromboembolism,2 the surgeon should be notified of its presence in the event that elective repair of the aneurysm is declined.
Patients with true ventricular aneurysms often have increased LVEDV and LVESV. Because a large portion of the potential stroke volume is “ejected” into the dyskinetic segment, calculated EF may be severely reduced, and overall systolic performance of the contractile myocardium underestimated. Because EF is a highly regarded predictor of morbidity and mortality,5 calculated EF may erroneously label patients as having a worse prognosis, or deem them as nonsurgical candidates for ventricular remodeling procedures that can improve geometry and preserve long-term systolic function.3 In fact, an estimated contractile EF of <30% constitutes a relative contraindication to surgical ventricular remodeling.2 The discernment of nonaneurysmal wall function and EF of the contractile segment may be a more relevant measure for risk stratification. Thus, the ability to predict postoperative EF in patients with LV aneurysms may be of value when surgical intervention is being considered.
In the described case, LV chamber measurements including the aneurysm were measured and were comparable to known preoperative CMRI values (Table 1). Although this application of 3D TEE is not entirely new,6 the semiautomated technique for predicting postaneurysmectomy LVEDV, LVESV, and LVEF using virtual resection from 3D TEE full-volume data sets, to our knowledge, has not been reported. Despite the additional time required for image acquisition and off-line analysis, the proposed method demonstrating a potential use for 3D TEE in predicting LV chamber dimensions and EF after aneurysm resection is novel and promising. Because conclusions about accuracy and validity cannot be drawn from a single case report, a prospective, blinded investigation using a larger population and nonsubjective methods is warranted. Ultimately, 3D TEE may permit the development of virtual surgical platforms to assist in perioperative risk stratification, clinical decision-making, and surgical planning.7
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3. Brown SL, Gropler RJ, Harris KM. Distinguishing left ventricular aneurysm from pseudoaneurysm. Chest 1997;111:1403–9
4. May BV, Reeves ST. Contained rupture of a left ventricular pseudoaneurysm. Anesth Analg 2007;105:38–9
5. White HD, Norris RM, Brown MA, Brandt PW, Whitlock RM, Wild CJ. Left ventricular end-systolic volume as the major determinant of survival after recovery from myocardial infarction. Circulation 1987;76:44–51
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APPENDIX: VIDEO LEGENDS
Video 1: Transgastric short-axis view of left ventricle (LV) and basal inferolateral true aneurysm with dimensions and intracavitary spontaneous contrast.
Video 2: Precardiopulmonary bypass left ventricular volumetric model including the aneurysm, created using a 3-dimensional transesophageal echocardiographic matrix array probe and commercial software. Images within the 4 displayed quadrants represent a cropped nonforeshortened midesophageal 5-chamber view (upper left), a midesophageal 2-chamber view (upper right), a transgastric mid short-axis view (lower left), and a volumetric model (lower right). Basal wall segments are labeled for reference. Quantitative data are included in Table 1.
Video 3: A, Precardiopulmonary bypass left ventricular (LV) volumetric model excluding the aneurysm, created using a 3-dimensional transesophageal echocardiographic (3D TEE) matrix array probe and commercial software by manually adding additional reference points to exclude the aneurysm, to predict postoperative LV chamber dimensions and function. B, Postcardiopulmonary bypass LV volumetric model created immediately after surgical aneurysmectomy and prosthetic patch repair, using a 3D TEE matrix array probe and commercial software. Images within the 4 displayed quadrants represent a cropped nonforeshortened midesophageal 5-chamber view (upper left), a midesophageal 2-chamber view (upper right), a transgastric mid short-axis view (lower left), and a volumetric model (lower right). Basal wall segments are labeled for reference. Quantitative data are included in Table 1. Cited Here...
MSA formatted the images and prepared the manuscript; RK and FYC assisted in preparing the manuscript; and SKS acquired and formatted the images and prepared the manuscript.
SKS has received support from Philips Healthcare, Inc. as a speaker. The other authors report no conflicts of interest.
Clinician's Key Teaching Points By Nikolaos J. Skubas, MD, Roman M. Sniecinski, MD, and Martin J. London, MD
* In left ventricular (LV) aneurysm, there is a regional dilation of the ventricular cavity containing (in the case of a true aneurysm) all myocardial layers. It is usually caused by a transmural myocardial infarction and results in reduced ejection fraction (EF), arrhythmias, and cardiac failure. Surgical remodeling (resection) is indicated to restore normal geometry as long as EF is not <30%.
* Preoperative transesophageal echocardiography (TEE) should be used to exclude thrombus within the aneurysm cavity and assess the severity of mitral regurgitation caused by papillary muscle dysfunction. The irregular LV shape, however, may make assessment of EF difficult using standard techniques.
* In this case, 3-dimensional TEE was used before the procedure to model what the LV cavity would look like without the aneurysm. This allowed the authors to more accurately predict the postresection LV end-diastolic and end-systolic volumes and EF, which were all similar to postoperative transthoracic echocardiographic measurements 1 month later.
* Using 3-dimensional TEE may allow improved prediction of postresection cavity volumes in LV aneurysm surgery, which could improve surgical planning and risk stratification.
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