A 46-yr-old man underwent bioprosthetic aortic valve replacement, ascending aortic arch aneurysm repair, and graft repair of the left main coronary artery. The surgery was complicated by postbypass left ventricular failure requiring intraoperative Levitronix (Levitronix GMBH, Waltham, MA) left ventricular assist device (LVAD) placement and subsequent implantation of a HeartMate II LVAD (Thoratec, Pleasanton, CA). Two days after HeartMate II placement and 9 days after the original surgery, the patient returned to the operating room for sternal closure and transesophageal echocardiography (TEE) examination revealing multiple thrombi in the left ventricular outflow tract, aortic root, and right atrium. The surgical plan was altered to include initiation of cardiopulmonary bypass to allow for closure of the aortic valve, revision of the coronary graft, and removal of all visualized clots.
Post–cardiopulmonary bypass imaging revealed a new hypoechoic mass between the endocardium and epicardium along the right posterior wall of the left atrium (LA) extending into the lateral wall (Fig. 1) (Video 1; please see video clips available at www.anesthesia-analgesia.org; see Supplemental Digital Content 1, http://links.lww.com/AA/A22, midesophageal, 4-chamber view demonstrating the initial view of a left atrial mass during weaning from cardiopulmonary bypass and initiation of left ventricular assist device [LVAD] flow [with Color flow Doppler]; in this video, the following can be seen: severely depressed left ventricular function and a hypoechoic space between the endocardium and epicardium of the left atrial wall; no communication between the left atrium [LA] and the hypoechoic mass is visualized with color flow Doppler; RA = right atrium; RV = right ventricle; LV = left ventricle). After protamine administration, the mass became more hyperechoic. Intramural dissection was diagnosed. Continued expansion of the intramural hematoma threatened to impede blood flow from the LA into the left ventricle and to reduce LVAD performance (Fig. 2). Direct surgical inspection revealed a large intramural thrombus, which was excised (Video 2; please see video clips available at www.anesthesia-analgesia.org; see Supplemental Digital Content 2, http://links.lww.com/AA/A23, midesophageal, 4-chamber view demonstrating the left atrium [LA] after removal of an intramural thrombus; in this video, the following can be seen: normalization of left atrial size after intramural thrombectomy; left ventricular assist device [LVAD] inflow cannula in the apex of the left ventricle [LV], and a dilated right ventricle [RV]; RA = right atrium). Postoperatively, the patient’s clinical condition improved, and he was discharged home with a HeartMate II LVAD to await heart transplantation.
LA dissection is a rare complication of cardiac surgery that typically occurs after mitral valve surgery.1,2 It has also been reported after coronary artery bypass graft surgery, after blunt trauma or myocardial infarction, and may also occur spontaneously.2–4 In the case presented above, the LA dissection resulted from cannulation of the right superior pulmonary vein (RSPV) during the original surgery and subsequent Levitronix LVAD placement. Cardiac manipulation, heparinization, and the “sucking” effect of the HeartMate II LVAD propagated the dissection into the LA during the surgery described above.
LA dissection typically appears as a hypoechoic space from the mitral/tricuspid origin extending along the interatrial septum or LA wall.2 However, pericardial blood impinging on the LA wall may mimic these findings.5 Manual surgical exploration eliminated any trapped fluid behind the heart and excluded pericardial fluid as the cause of the LA mass. Further TEE examination of the LA revealed that the luminal border of the mass pulsated with the cardiac cycle. This type of analysis is ideally done with continuous electrocardiographic recording on the TEE display monitor. Similar to what is seen in aortic dissections, the false cavity is compressed during systole as the LA is being filled (Video 1; see Supplemental Digital Content 1, http://links.lww.com/AA/A22). M-mode is a useful tool often used in aortic dissections to help identify the false and true lumen. M-mode is excellent at distinguishing subtle movement of the intima or, in this case, the endocardium in relation to the cardiac cycle. Color flow Doppler can be used to examine the endocardium for a tear and point of communication with the chamber. Pulsed wave Doppler can also be used to identify flow across a tear and may reveal if the source of blood is from a high or low pressure source. Other entities that should be considered when an LA mass is visualized are thrombi, left atrial myxomas, cysts, coronary aneurysms, or other cardiac tumors.6 LA thrombi are the most frequently visualized LA masses and usually originate in the LA appendage, may be mobile or free floating, and are intraluminal masses as opposed to the intramural mass seen in this case.
TEE clearly assisted in making the correct diagnosis in this case. An LA myxoma or other tumor would be present on the initial TEE examination. A new LA thrombus is not likely in a fully heparinized patient. Using continuous monitoring of the mass with TEE during protamine administration, we were clearly able to see the temporal relationship between reversal of heparin and the changing appearance of the mass from mostly fluid-filled hypoechoic mass to hyperechoic mass as the blood clotted (Fig. 1 versus Fig. 2). This finding helped to confirm our diagnosis of LA dissection by revealing the mass as a hematoma with a constant supply of blood.
To examine an LA dissection for possible extension into the pulmonary veins, it is necessary to examine all 4 pulmonary veins at their junctions with the LA. This can be accomplished starting at the midesophageal 4-chamber view. By rotating the probe to the right and withdrawing slightly, the RSPV can often be visualized. In this case, the expanding hematoma can be followed toward the RSPV, which had been the previous left ventricular sump and Levitronix LVAD inflow cannula site (Fig. 3) (Video 3; please see video clips available at www.anesthesia-analgesia.org; see Supplemental Digital Content 3, http://links.lww.com/AA/A24, midesophageal, 4-chamber view rotated to the right and withdrawn to view the right superior pulmonary vein [RSPV]; in this video, note the left atrium [LA] dissection extending from the RSPV; RA = right atrium). Advancing the probe and rotating further to the right brings the right lower pulmonary vein into view. Color flow Doppler is a helpful adjunct. The left-sided pulmonary veins can be visualized using the same technique but rotating the probe to the left. This technique is particularly useful in identifying the pulmonary vein anatomy in cases of congenital anomalous pulmonary venous return. Another method to visualize the RSPV is to rotate the probe to the right from the midesophageal bicaval view; the RSPV can be seen entering the LA from the bottom right of the screen.
Postdecannulation dissection is a well-described complication that is usually associated with high-pressure arterial cannulation sites. However, we present a case of dissection from a theoretically low-pressure cannula site, and to our knowledge, there are no previous reports in the literature describing pulmonary vein and LA dissection occurring after removal of an LVAD inflow cannula. This case underscores the importance of TEE in monitoring and diagnosing complications associated with vascular or cardiac cannulation.
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6. Alomar-Melero E, Martin TD, Janelle GM, Peng YG. An unusual giant right coronary artery aneurysm resembles an intracardiac mass. Anesth Analg 2008;107:1161–2
Clinician’s Key Teaching Points
By Roman M. Sniecinski, MD, Nikolaos J. Skubas, MD, and Martin J. London, MD
- In this case, retrograde dissection of the left atrial wall was caused by cannulation of a pulmonary vein. The primary differential diagnosis was a pericardial blood collection. M-mode and Doppler evaluation of pulsatility, endocardial disruption and blood entry into the wall were used to establish the diagnosis.
- Examination of the 4 pulmonary veins at their entry into the left atrium is important as a dissection may extend into any of them.
- In the midesophageal (ME) 4-chamber view, the left upper pulmonary vein is seen entering the left atrium immediately lateral to the left atrial appendage. At the same depth, rightward rotation of the TEE probe will help image the right upper pulmonary vein. The lower pulmonary veins are imaged equilateral to the upper ones, by further rotating and advancing the probe 1-2 cm.
- Alternatively, the pulmonary veins can be seen on the right side of the image sector in the ME bicaval view by rotating the probe to the right (for the right pulmonary) or left (for the left pulmonary veins).