E ECHO ROUNDS

Inferior Vena Cava Obstruction after Total Artificial Heart Implantation Kent H. Rehfeldt, MD, Erica D. Wittwer, MD, PhD, and William J. Mauermann, MD CASE PRESENTATION

A 51-year-old man with cardiac amyloidosis was admitted to the hospital with New York Heart Association class IV symptoms, requiring the initiation of epinephrine and milrinone infusions. Transthoracic echocardiography revealed thickened left ventricular walls with restrictive diastolic filling, a calculated ejection fraction of 13%, and severely reduced right ventricular systolic function. He was scheduled for implantation of a total artificial heart (TAH) (SynCardia Systems, Tucson, AZ) as a bridge to transplantation. Intraoperative transesophageal echocardiography (TEE) before cardiopulmonary bypass confirmed severe biventricular systolic dysfunction and excluded intracardiac thrombus and patent foramen ovale. After TAH implantation, TEE was used to monitor air evacuation and ensure proper prosthetic valve function (Video 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A899). A midesophageal (ME) bicaval view, modified by slight probe advancement, was used to verify unimpeded inferior vena cava (IVC) flow (Fig. 1, A–C, Video 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A899). Likewise, a ME 2-chamber view with leftward and rightward rotation confirmed normal pulmonary vein (PV) flow velocities. With sternal closure, there was a reduction in TAH flow from 6.7 to 3.9 L/min. TEE examination again showed normal PV velocities. However, the IVC near its junction with the right atrium (RA) was narrowed by a tissue infolding to a luminal diameter of 0.5 cm, and color flow acceleration was apparent (Fig. 2, A–B, Video 2, see Supplemental Digital Content 2, http://links.lww.com/AA/A900). Spectral Doppler interrogation of flow entering the RA from the IVC revealed a peak velocity of 140 cm/s (Fig. 2C). The sternum was reopened, and the surgeon placed a suture to anchor the driveline to the left chest wall, resulting in overall leftward and anterior device displacement. Subsequently, the proximal IVC diameter increased to 1.7 cm with laminar color flow (Video  3, see Supplemental Digital Content 3, http://links.lww.com/AA/A901). Blood velocity entering the RA from the IVC decreased to 74 cm/s. The sternum was again closed, this time with TAH flow maintained at 6.8 L/min and no TEE evidence of venous flow obstruction. The patient provided consent for publication.

DISCUSSION

Clinical use of the SynCardia TAH continues to increase with >1200 devices implanted worldwide. Unlike axial flow left ventricular assist devices that do not provide direct right heart support, the TAH may be selected for patients with severe biventricular dysfunction and is approved in the United States both as a bridge to transplantation and as destination therapy. The history, indications, technical aspects, and general applications of TEE during TAH implantation have recently been reviewed.1–4 Clinicians have recognized venous inflow obstruction after TAH implantation for more than a decade.5 Copeland et al.6 noted that 6 of 62 patients had unspecified “fit problems,” and 4 required reoperation to reposition the device. Compression or kinking of the IVC and PVs may occur at the time of implantation or with sternal closure.2 Should venous compression be noted, the surgeon may elect to place a suture around the neoventricle or driveline and anchor it to the left chest wall to improve venous inflow. By pulling the rigid right neoventricle leftward and anterior and away from the IVC, direct compression or torquing of this relatively low-pressure, venous structure can be ameliorated (Fig.  3). Most devices currently in use have a maximum stroke volume of 70 cc and a total device volume of 750 cc.2 In an attempt to prevent fit problems and compression of venous structures, patient selection criteria for TAH implantation have traditionally included a body surface area greater than 1.7 m2. However, a smaller version of the TAH has recently been developed and may reduce the occurrence of venous obstruction. Although often mentioned in general terms,1–6 to our knowledge, this is the first specific report detailing the TEE

From the Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota. Accepted for publication January 24, 2014. 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 website (www.anesthesia-analgesia.org). Reprints will not be available from the authors. Address correspondence to Kent H. Rehfeldt, MD, Department of Anesthesiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905. Address e-mail to [email protected]. Copyright © 2014 International Anesthesia Research Society DOI: 10.1213/ANE.0000000000000244

26 www.anesthesia-analgesia.org

Video 1. Part 1), A midesophageal (ME) 4-chamber view demonstrating adequate air evacuation from the right atrium (RA) and left atrium (LA) along with normal motion of the tilting disk mechanical valves in the tricuspid and mitral positions. Part 2), A modified ME bicaval view showing a widely patent inferior vena cava (IVC) as it enters the RA. Part 3), A modified ME bicaval view with color Doppler imaging showing laminar RA inflow from the IVC. July 2014 • Volume 119 • Number 1

IVC Obstruction and Total Artificial Heart

Figure 1. A, Midesophageal bicaval view modified by slight probe advancement showing the junction of the inferior vena cava (IVC) and right atrium (RA). The IVC-RA junction is widely patent with a diameter (arrows) of 2.1 cm. Ascites (asterisk) is noted. B, Laminar blood flow entering the RA from the IVC is apparent by the low velocity, homogenous color Doppler signal obtained with the aliasing velocity at 31 cm/s. C, Pulsed-wave Doppler interrogation of blood flow entering the RA from the IVC demonstrates a velocity of 57 cm/s.

Figure 2. A, Midesophageal modified bicaval view showing the junction of the inferior vena cava (IVC) and right atrium (RA). The IVC adjacent to the RA has been narrowed by infolding of tissue with a resultant diameter (double-headed arrow) of 0.5 cm. B, Acceleration of RA inflow from the IVC is apparent by the mosaic color Doppler signal despite the increased aliasing velocity of 62 cm/s. C, Continuous wave Doppler interrogation of blood flow entering the RA from the IVC demonstrates an increased velocity of 140 cm/s.

Video 2. Part 1), A modified midesophageal (ME) bicaval view showing the inferior vena cava (IVC) adjacent to the right atrium (RA) narrowed by an infolded ridge of tissue. Part 2), A modified ME bicaval view showing color Doppler evidence of flow acceleration at the point of IVC narrowing.

July 2014 • Volume 119 • Number 1

Video 3. Part 1), A modified midesophageal (ME) bicaval view showing an increased inferior vena cava (IVC) diameter after leftward displacement of the total artificial heart. Part 2), A modified ME bicaval view with color Doppler showing a return of laminar flow of blood from the IVC into the right atrium (RA).

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E Echo Rounds

Figure 3. A, Sketch depicting the right neoventricle attached to the right atrium (RA). A kinking or tissue infolding at the RA-inferior vena cava (IVC) junction is present (open arrow). The superior vena cava (SVC), pulmonary artery (PA), and device drive line (DL) are also labeled. B, Sketch depicting placement of a suture (solid arrow) around the DL used to pull the right neoventricle leftward and anterior, relieving the obstruction at the RA-IVC junction.

findings of IVC obstruction after TAH implantation. Normal IVC diameter is 1.2 to 1.7 cm.7 However, normal IVC blood velocity during positive pressure ventilation as measured by TEE has not been well described. In healthy, spontaneously breathing volunteers, a peak resting IVC velocity ranging from 30 to 45 cm/s has been measured by invasive catheter.8 This same study found a significant increase in IVC velocity with exercise, with values as high as 147 cm/s.8 Typical IVC velocity after TAH insertion has not been reported. TEE imaging of the IVC after TAH insertion may be accomplished using a modified ME bicaval view with slight probe advancement. In this view, the IVC is relatively perpendicular to the ultrasound beam, affording the opportunity to measure diameter though less ideal for velocity determination. In our case, the angle of blood flow entering the RA from the IVC was such that reasonable Doppler alignment was possible. After device repositioning, IVC inflow velocity decreased by approximately 50%, while the diameter more than doubled. Although there are no specific criteria to diagnose IVC obstruction in this setting, the combination of an unexpectedly small diameter, flow acceleration by color Doppler, and blood velocities in the range of 100 cm/s may suggest the need for intervention. In addition to flow acceleration at the site of obstruction, IVC dilation and reduced flow proximal to the stenosis may also be noted.7 This may manifest as monophasic hepatic vein flow with peak velocities

Inferior vena cava obstruction after total artificial heart implantation.

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