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Left Atrial Dissection: Natural Progression Through Imaging

Martinelli, Susan M. MD*; Berry, John MD*; Dalal, Nishita MD*; Stansfield, William MD; Moylan, Vincent J. Jr MS, PA(ASCP)cm; Kumar, Priya MD*

doi: 10.1213/ANE.0000000000000449
Cardiovascular Anesthesiology: Echo Rounds
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From the Departments of *Anesthesiology and Surgery, University of North Carolina, Chapel Hill, North Carolina; Department of Pathology, University of North Carolina, Chapel Hill, North Carolina.

Accepted for publication July 19, 2014.

Funding: No external funding was utilized.

The authors declare no conflicts of interest.

Patient Consent Statement: The patient’s family gave informed consent for this Echo Rounds submission and subsequent publication.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website.

Reprints will not be available from the authors.

Address correspondence to Susan M. Martinelli, MD, Department of Anesthesiology, University of North Carolina, N2201 UNC Hospitals, CB#7010, Chapel Hill, NC 27599. Address e-mail to smartinelli@aims.unc.edu.

A 74-year-old male underwent coronary artery bypass grafting, bioprosthetic aortic valve replacement, and a supracoronary ascending aortic aneurysm repair. The pre-procedure transesophageal echocardiogram (TEE) was remarkable for moderate aortic insufficiency, moderate aortic stenosis, an ejection fraction of 40% to 50%, and an ascending aortic aneurysm. Intraoperatively, despite multiple attempts and TEE guidance, the surgeons were unable to cannulate the coronary sinus for delivery of retrograde cardioplegia. There was intermittent delivery of cardioplegia into the individual coronary ostia as needed throughout the surgery, which provided adequate myocardial protection demonstrated through electrical silence. The surgery was complicated by an iatrogenic tear of the right coronary ostium during cardioplegia administration, which was repaired.

After weaning from cardiopulmonary bypass, the TEE examination demonstrated a distended, hypokinetic right ventricle (RV) and an underfilled left ventricle. Multiple midesophageal views revealed a new echogenic filamentous structure, approximately 4 cm in length, bisecting and attached to the left atrial (LA) wall (Fig. 1; Video 1, Supplemental Digital Content 1, http://links.lww.com/AA/B6). This was suspicious for an LA dissection. Color flow Doppler interrogation demonstrated laminar flow through the pulmonary veins, mitral valve (MV), and LA (Video 2, Supplemental Digital Content 2, http://links.lww.com/AA/B7). No color flow was noted on the posterior and lateral sides of the tissue flap. Due to RV failure despite maximal inotropic support, a temporary extracorporeal RV assist device was placed. The evolving morphology of the LA dissection was followed with serial TEE examinations during the patients 3 additional return trips to the operating room. These demonstrated the evolution of the dissection flap from a fluid-filled hypoechoic lumen to a heterogeneous hyperechoic structure consistent with thrombus (Fig. 2A and Video 3, Supplemental Digital Content 3, http://links.lww.com/AA/B8). Pulmonary vein flow, MV inflow, and LA size were evaluated at each opportunity and largely unchanged. The thrombus within the LA wall was noted to be resolving on postoperative day 11 (Fig. 2B).

Figure 1

Figure 1

Figure 2

Figure 2

Unfortunately, the patient succumbed to multisystem organ failure on postoperative day 13.

At autopsy, an LA dissection measuring 4.2 cm by 3.9 cm was found in the LA, adjacent to the coronary sinus (Fig. 3). The cause of death was determined to be an extensive transmural infarction of the RV due to a complete occlusion of the right coronary artery, likely secondary to the intraoperative iatrogenic right coronary artery injury.

Figure 3

Figure 3

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DISCUSSION

LA dissection is a rare and potentially devastating complication of several common cardiac surgical procedures.1–3 As demonstrated in this case, it typically evolves from a hypoechoic space along the wall of the LA to an intramural hyperechoic expanding globular mass (Fig. 2; Video 3, Supplemental Digital Content 3, http://links.lww.com/AA/B8). It is most commonly seen with MV and aortic valve surgery but has also been associated with coronary sinus injury and acute myocardial infarction.1–4 Additionally, pulmonary vein cannulation for left ventricular venting and blunt chest trauma have been described as precipitating factors.1–3,5 The incidence is difficult to estimate, but the highest estimate reported is 0.86%.1 The clinical course can vary from indolent to acute or late onset cardiogenic shock.2 The mechanism of cardiogenic shock in LA dissection is typically due to obstruction of flow through the LA.1,5

Examining the LA in the midesophageal 4-chamber, 2-chamber, and long-axis views best demonstrates an LA dissection. It is vital to sequentially assess the flow characteristics through the LA since an initially non-obstructive LA dissection may evolve into an obstructive hematoma requiring surgical intervention. This becomes especially important with the reversal of anticoagulation. Color flow Doppler interrogation of the MV and each of the pulmonary veins demonstrating laminar flow is essential to exclude flow obstruction.

The differential diagnosis for an LA mass is extensive. A pericardial hematoma causing external compression of the cardiac chamber may appear similar in appearance to a thrombosed LA dissection. However, an important echocardiographic differentiating factor for an LA dissection is its initial presentation as a filamentous structure attached to the endocardial surface evolving into an intramural echogenicity. Similarly, tumor, cyst, vegetation, or coronary aneurysm each would present on the initial TEE examination. Cor triatriatum sinister, the congenital presence of a membrane in the LA, could appear echocardiographically similar to the early stages of LA dissection. However, it would not evolve through the stages as demonstrated above. An intraluminal thrombus may resemble the intermediate stages of an LA dissection; however, it is typically a mobile or free-floating echogenicity and is unlikely in a fully heparinized patient. There has been a report of coronary sinus injury with percutaneous placement of the retrograde cardioplegia cannula that was diagnosed through extravasation of contrast on fluoroscopy as well as air and fluid found in the pericardial space on TEE.6 A coronary sinus rupture from retrograde cardioplegia cannulation is typically recognized when bleeding and low line pressures are associated with cardioplegia administration or through an atrioventricular groove hematoma.7 Atrioventricular groove hematomas appear as echolucencies in close proximity to the LA free wall, running alongside the MV annulus. They are primarily associated with MV surgery and can be recognized by surgical inspection of the exterior of the heart.8

A previous report2 describes an LA dissection consequent to pulmonary vein cannulation hypothesizing its exacerbation by the negative pressure created by the left ventricular assist device. It was discovered 9 days after the initial surgery, at which time it was surgically removed. There are several key differences in the present report as compared to the previous one, including repeated visits to the operating room allowing us to capture an echocardiographic natural progression of this pathologic process. The LA dissection in the present case resulted from trauma around the coronary sinus ostium and was appreciated immediately after cardiopulmonary bypass. It evolved from a filamentous flap-like structure in the LA to hypoechoic cystic mass which proceeded on to a hyperechoic intramural hematoma which finally began to show natural regression.

LA dissection is a rare but recognized complication in cardiac surgery. While in an unobstructed patient it may have no harmful consequences, a high level of suspicion should be maintained to assess for pulmonary vein or LA outflow obstruction which may lead to cardiogenic shock. This case is unique because the natural progression of the LA dissection was documented with echocardiographic imaging from the initial occurrence throughout the patient’s hospital course concluding with an autopsy verification of the presumed diagnosis.

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Clinician’s Key Teaching Points

By Kent H. Rehfeldt, MD, Roman M. Sniecinski, MD, and Martin J. London, MD

  • Left atrial dissection is an uncommon iatrogenic injury after cannulation of the coronary sinus or pulmonary veins, or surgery on the mitral or aortic valves. It can also occur as a complication of blunt chest trauma or myocardial infarction. The clinical course is often self-limited but can be catastrophic if the dissection obstructs blood flow into or out of the left atrium.
  • The left atrium is well visualized in several midesophageal views as the transesophageal echocardiogram (TEE) probe lies directly behind it. On 2-dimensional examination, a dissection flap initially presents as a linear structure arising from the left atrial endocardium, bisecting the chamber. Color flow Doppler should be used to determine the presence or absence of flow between the dissection flap and the atrial wall.
  • In this case of a left atrial dissection resulting from attempted coronary sinus cannulation, serial TEE examinations were used to monitor its progression from a hypoechoic, fluid-filled space to a heterogeneous, hyperechoic structure consistent with development of organized thrombus. Importantly, color flow Doppler confirmed that pulmonary venous and mitral inflow were not obstructed.
  • The intraoperative echocardiographer should be familiar with the characteristics of left atrial dissection to differentiate it from other types of iatrogenic pathology involving the atria, such as pericardial hematoma or atrioventricular groove separation. Based on the clinical circumstances, serial examinations may be useful.
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DISCLOSURES

Name: Susan M. Martinelli, MD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Susan M. Martinelli approved the final manuscript.

Name: John Berry, MD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: John Berry approved the final manuscript.

Name: Nishita Dalal, MD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Nishita Dalal approved the final manuscript.

Name: William Stansfield, MD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: William Stansfield approved the final manuscript.

Name: Vincent J. Moylan, Jr, MS, PA(ASCP)cm.

Contribution: This author helped autopsy photo.

Attestation: Vincent J. Moylan, Jr, approved the final manuscript.

Name: Priya Kumar, MD.

Contribution: This author helped analyze the data and write the manuscript.

Attestation: Priya Kumar approved the final manuscript.

This manuscript was handled by: Martin J. London, MD.

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REFERENCES

1. Di Gregorio O, Nardi C, Milano A, De Carlo M, Grana M, Bortolotti U. Dissection of atrial septum after mitral valve replacement. Ann Thorac Surg. 2001;71:1670–2
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3. Musat I, Hieber C, Kepka A, Novotny P, Poslussny P, Schwarz S, Fitzgerald RD. Intramural left atrial hematoma after aortocoronary artery surgery. Anesth Analg. 2003;97:1605–7
4. Poirier NC, Ugolini P, Pellerin M, Petitclerc R, Tardif JC. Transesophageal echocardiographic evaluation of perioperative coronary sinus trauma. Ann Thorac Surg. 1998;66:573–5
5. Gallego P, Oliver JM, González A, Domínguez FJ, Sanchez-Recalde A, Mesa JM. Left atrial dissection: patho- genesis, clinical course, and transesophageal echocar - diographic recognition. J Am Soc Echocardiogr. 2001;14:813–20
6. Krishnan S, Papworth DP, Farivar RS, Ueda K. Identification of coronary sinus injury by transesophageal echocardiography during placement of a retrograde cardioplegia catheter for minimally invasive cardiac surgery. Anesth Analg. 2013;116:560–2
7. Economopoulos GC, Michalis A, Palatianos GM, Sarris GE. Management of catheter-related injuries to the coronary sinus. Ann Thorac Surg. 2003;76:112–6
8. Kumar A, Fitzsimons B, Trombetta C. Echo rounds: atrioventricular groove hematoma during mitral valve/tricuspid valve repair: transesophageal echocardiography characteristics. Anesth Analg. 2013;116:986–8

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