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Intraoperative Transesophageal Echocardiography of a Left Atrial Mass After Total Artificial Heart Implantation

Maldonado, Yasdet MD; Troianos, Christopher A. MD; Marks, Barry DO; Zhang, Qin MD; Dishart, Michael MD

doi: 10.1213/ANE.0b013e31829f9ed2
Cardiovascular Anesthesiology: Echo Rounds
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Supplemental Digital Content is available in the text.Published ahead of print July 18, 2013

From the Department of Anesthesiology, Allegheny Health Network, Pittsburgh, Pennsylvania.

Accepted for publication May 19, 2013.

Published ahead of print July 18, 2013

Funding: None.

The authors declare no conflicts of interest.

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 Web site.

Reprints will not be available from the authors.

Address correspondence to Yasdet Maldonado, MD, Allegheny Health Network, Department of Anesthesiology, 320 East North Ave., Pittsburgh, PA 15212. Address e-mail to ymaldona@wpahs.org.

A 62-year-old man with ischemic cardiomyopathy presented with acute biventricular heart failure after a witnessed cardiac arrest. He was emergently placed on extracorporeal membrane oxygenation and subsequently underwent implantation of a SynCardia® Total Artificial Heart (TAH; SynCardia Systems, Inc, Tucson, AZ). Written informed patient consent was obtained for publication of this report. Intraoperative transesophageal echocardiography (TEE) examination revealed anatomically normal native atria and severe biventricular failure. The TAH was implanted, the patient was separated from cardiopulmonary bypass (CPB), and anticoagulation was reversed with protamine. TEE examination demonstrated a rapidly enlarging mass along the anterolateral aspect of the left atrium (LA) that appeared to extend into the LA chamber during atrial ejection (Fig. 1; Video, see Supplemental Digital Content 1, http://links.lww.com/AA/A569). The homogenous mass had smooth borders and echogenicity consistent with soft tissue. The mass did not appear to impede flow from the pulmonary veins nor through the mechanical atrioventricular valves, as evaluated with color-flow Doppler (CFD) and pulse-wave Doppler (PWD). The patient’s arterial blood pressure was not affected; however, central venous pressure, filling volumes, and cardiac output were decreased.

Figure 1

Figure 1

The echocardiographic appearance of the mass, being consistent with that of the LA wall, prompted the surgeons to review the vacuum settings on the device. This revealed that the vacuum had been turned on prematurely, despite the manufacturer’s recommendation that the vacuum remain off until after mediastinal closure.a The native LA mass completely disappeared (Fig. 2; Video, see Supplemental Digital Content 2, http://links.lww.com/AA/A570) when the vacuum was turned off and with administration of fluids.

Figure 2

Figure 2

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DISCUSSION

There are currently 2 options for mechanical circulatory support for patients suffering from biventricular heart failure: biventricular-assist devices and the SynCardia TAH. Biventricular-assist devices provide support for the native heart by way of 2 pumps each attached to a ventricle. On the contrary, the SynCardia TAH replaces the failing heart rather than just supporting it. The SynCardia TAH eliminates the source of failure whether it be due to ventricular failure, valve dysfunction, or rhythm problems. It is used as a bridge for cardiac transplantation and consists of 2 artificial ventricles connected to an external pneumatic driver (SynCardia) and 4 Medtronic Hall® tilting disk valves (Medtronic, Minneapolis, MN). The left and right atria, interatrial septum, aorta, and pulmonary artery remain intact as inflow connectors composed of polyurethane are sewn to both atria and then snapped onto the inflow valve mount of the artificial ventricles. The outflow connectors composed of Dacron are sewn into the pulmonary artery and aorta and then snapped to the outflow valve mounts. It is generally considered best practice to not apply vacuum if the surgeon is placing any sutures in the atria. Approximately 10 mm Hg vacuum may be started as soon as sewing is completed on the TAH connection points.a This vacuum facilitates filling of the ventricles.

Visualization of a new left atrial mass on TEE after CPB typically raises concern for a thrombus or inverted LA appendage. A thrombus would be independently mobile, have irregular borders, and be associated with spontaneous echo contrast.1 Vegetations or tumors are also considered in the differential diagnosis, but these are usually initially observed pre-CPB and will not appear acutely in the post-CPB period. Vegetations are typically attached to the upstream side of the valve, irregular, mobile, and may affect the integrity of surrounding tissues. Tumors in the LA, such as myxomas, have a heterogeneous appearance and are often attached to the fossa ovalis. Rarely, native wall tissue is visualized as a mass. Inverted native wall tissue can be identified by its temporal appearance post-CPB, smooth borders, and echogenicity consistent with soft tissue. Potential hemodynamic findings associated with native wall inversion after a TAH include hypotension and a decrease in central venous pressure, device fill volume, and device cardiac output as a consequence of hypovolemia and/or vacuum settings. The fill volumes and cardiac outputs (both right and left ventricle) are displayed in real time on the computer display of the SynCardia driver. Accurate diagnosis of a post-CPB mass after TAH implantation is important as treatment may include reinstitution of CPB and unnecessary surgical exploration.

TEE examination (Table 1) before TAH implantation requires careful evaluation of the native atria, including inspection of the atrial septum for the presence of a patent foramen ovale. All 4 pulmonary veins should be evaluated with 2-dimensional imaging (2D), CFD, and PWD to determine patency and baseline velocities that will be used for post-CPB comparison. Similarly, the patency of the inferior vena cava (IVC) and hepatic vein should be evaluated with 2D, CFD, and PWD for future comparison.

Table 1

Table 1

Assessment of de-airing maneuvers before separation from CPB includes imaging the ascending aorta in the midesophageal aortic valve long-axis view. The pulmonary veins, IVC, and hepatic vein are evaluated for obstruction immediately post-CPB and also after chest closure. Extrinsic compression of the pulmonary veins, especially the left-sided veins, and the IVC may occur leading to inadequate device filling from decreased venous return and ultimately possible device failure. CFD demonstrating turbulent flow and PWD spectral display with velocities exceeding 1 m/s suggest obstruction.2 The atrioventricular inflow valves (Fig. 2; Video, see Supplemental Digital Content 2, http://links.lww.com/AA/A570) are evaluated for characteristic regurgitant washing jets, 1 central jet and 2 outer washing jets that are usually apparent on the inflow side of the closed valve.3 The washing jets help reduce flow stagnation around the prosthetic valve. A paraprosthetic leak is possible if there is an anastomotic leak at the site of atrial connection, although this phenomenon has never been observed in the SynCardia TAH (S. Langford, SynCardia Systems, personal communication, March 15, 2013). Stenosis of the mechanical valves, although rare due to the universal size (27 mm) of the inflow valves, could occur due to gross valve dysfunction. The ventricular outflow valves will not be visible with TEE. The echocardiographer should evaluate the atrial septum again for a patent foramen ovale as it may be observed post-CPB due to new pressure gradients within the atria after TAH implantation. The general goals of a TEE examination in patients undergoing implantation of a SynCardia TAH include a thorough pre-CPB evaluation of the native heart (atria, atrial septum, pulmonary veins, hepatic vein) and assessment of the device and 4 connection sites post-CPB.

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Clinician’s Key Teaching Points

By Nikolaos J. Skubas, MD, Kent H. Rehfeldt, MD, Martin J. London, MD

  • The total artificial heart (TAH), used as a bridge to transplantation in cases of biventricular failure, replaces both ventricles with 2 pneumatically driven chambers equipped with inflow and outflow tilting disk mechanical valves. The native atria and great arteries are anastomosed to the inflow and outflow valves, respectively. Unobstructed connections and vacuum ensure filling and unimpeded output of the TAH.
  • The patency of the systemic and pulmonary venous inflow to the atria should be ensured before and after weaning from cardiopulmonary bypass (CPB) with 2-dimensional and Doppler echocardiography. Adequate de-airing can be confirmed by imaging the atria and great vessels, and although dysfunction is unlikely, atrioventricular prosthetic valve function should be assessed.
  • In this case, a left atrial mass with smooth borders and tissue density appeared after weaning from CPB concurrently with a decrease in TAH output. A decrease in the vacuum settings together with IV fluid infusion caused disappearance of the left atrial mass and restoration of TAH output, confirming the diagnosis of inverted left atrial wall.
  • The differential diagnosis of a left atrial mass includes thrombus, tumor, vegetation, and an inverted appendage. The absence of the mass during the pre-CPB transesophageal echocardiography examination made tumor or vegetation unlikely while the lack of independent motion and echo texture helped exclude thrombus.
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DISCLOSURES

Name: Yasdet Maldonado, MD.

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

Attestation: Yasdet Maldonado approved the final manuscript.

Name: Christopher A. Troianos, MD.

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

Attestation: Christopher A. Troianos approved the final manuscript.

Name: Barry Marks, DO.

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

Attestation: Barry Marks approved the final manuscript.

Name: Qin Zhang, MD.

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

Attestation: Qin Zhang approved the final manuscript.

Name: Michael Dishart, MD.

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

Attestation: Michael Dishart approved the final manuscript.

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

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FOOTNOTES

a SynCardia Systems Inc. CardioWest Total Artificial Heart (TAH) Directions for Use. Available at: http://www.fda.gov/ohrms/dockets/ac/04/briefing/4029b1_final.pdf. Accessed October 14, 2012.
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REFERENCES

1. Raja A, Arora H, Kumar PA. A new cardiac mass after cardiac transplantation. Anesth Analg. 2010;111:1369–71
2. Gaitan BD, Thunberg CA, Stansbury LG, Jaroszewski DE, Arabia FA, Griffith BP, Grigore AM. Development, current status, and anesthetic management of the implanted artificial heart. J Cardiothorac Vasc Anesth. 2011;25:1179–92
3. Flachskampf FA, O’Shea JP, Griffin BP, Guerrero L, Weyman AE, Thomas JD. Patterns of normal transvalvular regurgitation in mechanical valve prostheses. J Am Coll Cardiol. 1991;18:1493–8

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© 2013 International Anesthesia Research Society