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Cardiovascular Anesthesiology: Echo Rounds

Use of Intraoperative Transesophageal Echocardiography to Evaluate Positioning of TandemHeart® Percutaneous Right Ventricular Assist Device Cannulae

Kowalczyk, Anna K. MD*; Mizuguchi, K. Annette MD, PhD, MMSc; Couper, Gregory S. MD; Wang, Jue Teresa MD; Fox, Amanda A. MD, MPH

Author Information
doi: 10.1213/ANE.0000000000000039

A 67-year-old woman presented to our operating room (OR) for planned removal of a TandemHeart® percutaneous right ventricular assist device (pRVAD; Cardiac Assist, Pittsburgh, PA) that was placed at an outside hospital as a bridge to recovery from severe right ventricular (RV) dysfunction after coronary artery bypass graft surgery. When she presented to our OR, her pRVAD support had been weaned to <2 L/min of outflow. Before presenting to our OR, a pulmonary artery (PA) catheter that had been placed became dysfunctional, and a second PA catheter was floated under fluoroscopic guidance. The dysfunctional PA catheter was left in place to avoid inadvertent snaring and withdrawal of the pRVAD cannulae. We performed a full transesophageal echocardiographic (TEE) examination intraoperatively, focusing on confirming the correct position of the pRVAD cannulae.

A right ventricular assist device (RVAD) is an extracorporeal pump that drains blood from the right atrium (RA) via an inflow cannula (flow into the RVAD) and then delivers that blood to the PA via an outflow cannula (flow out of the RVAD). RVADs do not provide gas exchange, but they provide circulatory support that takes over some or all the work of the RV in the setting of RV failure. While TandemHeart support of the left ventricle is well described,1 the TandemHeart is used less frequently to support a failing RV. Several publications describe technical placement as well as medical and surgical management of pRVADs.2–4 However, while a published description of TEE evaluation of percutaneous left ventricular assist devices is available,1 there is a paucity of literature describing how to use TEE to evaluate pRVAD cannulae positioning and the related integrity and function of right heart structures that can be affected by the pRVAD.5

Our examination demonstrated the following: in the midesophageal RV inflow–outflow view, the pRVAD outflow cannula was seen traversing the pulmonary valve (PV) in conjunction with 2 PA catheters (Video 1, Clip 1, see Supplemental Digital Content 1, http://links.lww.com/AA/A683). Addition of Color flow Doppler (CFD) imaging (Fig. 1; Video 1, Clip 2, Supplemental Digital Content 2, http://links.lww.com/AA/A684) demonstrated mild, cannula-associated pulmonic regurgitation (PR). The tip of the outflow cannula was well positioned in the main PA (Video 1, Clip 1, Supplemental Digital Content 1, http://links.lww.com/AA/A683). Midesophageal bicaval and 4-chamber views demonstrated the pRVAD inflow cannula appropriately positioned in the mid RA (Video 1, Clip 2, Supplemental Digital Content 2, http://links.lww.com/AA/A684). Biventricular function was assessed, and the device was weaned to off and successfully explanted.

Figure 1
Figure 1:
Images of pRVAD outflow cannula with zoom feature of the RVOT and the PV acquired during a single heartbeat (systole and diastole), with the pRVAD support weaned to <2 L/min of outflow. Top panel demonstrates systole with no indication by CFD of pRVAD outflow into the RVOT proximal to the PV. Bottom panel demonstrates CFD evidence of mild cannula-associated PR. CFD = color flow Doppler; pRVAD = percutaneous right ventricular assist device; RVOT = right ventricular outflow tract; PV = pulmonic valve; PR = pulmonic regurgitation.

pRVAD inflow and outflow cannulae are often both placed via the femoral veins.3 However, in our patient, a 21F inflow cannula (draining into the pRVAD) was placed into the RA via the right femoral vein, and a 17F outflow cannula was positioned into the main PA via the right internal jugular vein (Fig. 2). The right internal jugular approach requires heightened vigilance for outflow cannula malposition that can occur with patient neck movement. Antegrade migration of the outflow cannula into a secondary branch of the PA can cause hypoxia and an acute decrease in pRVAD outflow if the smaller vessel wall occludes outflow orifices. Hemothorax or hemoptysis may occur if the PA branch is perforated.3 Partial or complete retrograde migration of the outflow cannula across the PV into the right ventricular outflow tract (RVOT) can result in RV distension, worsening RV failure, tricuspid regurgitation (TR), and cardiac arrhythmias, as the pRVAD is delivering blood into the RV rather than offloading the RV.3 When evaluating the TandemHeart pRVAD outflow cannula, it is important to note that blood flows out of the tip of the distal end, as well as through multiple outflow orifices located along the sides of the terminal 2 cm of the outflow cannula (Fig. 3). It is possible for the pRVAD outflow cannula tip to be positioned in the proximal main PA, while some of the side orifices are positioned in the RVOT, resulting in partial delivery of pRVAD outflow into the RVOT. In our patient, TEE confirmed that the pRVAD outflow cannula was positioned correctly within the main PA, with the tip >2 cm beyond the PV (Video 1, Clip 3, http://links.lww.com/AA/A683).

Figure 2
Figure 2:
Illustration of pRVAD inflow and outflow cannulae positions within the right heart and corresponding great vessels in our patient. IVC = inferior vena cava; PA = pulmonary artery; pRVAD = percutaneous right ventricular assist device; PV = pulmonic valve; RA = right atrium; RIJ = right internal jugular; SVC = superior vena cava; TV = tricuspid valve. The template (http://www.vectorstock.com/royalty-free-vector/heart-vector-831293) used in the creation of this figure was used with the permission of Vectorstock.com (http://www.vectorstock.com).
Figure 3
Figure 3:
Photograph of the distal tip of the pRVAD outflow cannula. Note the multiple side orifices for pRVAD outflow that open along the distal 2 cm of the cannula. pRVAD = percutaneous right ventricular assist device.

CFD imaging can be used to help differentiate retrograde outflow cannula malposition from the mild, isolated PR that was observed in our patient and that often occurs around a pRVAD outflow cannula (Fig. 1; Video 1, Clip 2, http://links.lww.com/AA/A683). With correct outflow cannula position, CFD will demonstrate laminar antegrade systolic flow within the RVOT during native RV ejection. Retrograde regurgitant flow across the PV secondary to PR around the outflow cannula is generally not severe and should only be evident by CFD during diastole (Fig. 1; Video 1, Clip 2, http://links.lww.com/AA/A683). Patients with significant PR before pRVAD insertion may not be good candidates for TandemHeart® pRVAD support. If CFD were to demonstrate turbulent flow within the RVOT throughout both systole and diastole, this would suggest retrograde malposition of the outflow cannula.

The inflow cannula to the pRVAD should be positioned where the tip is visible in the mid RA. It is possible to inadvertently position the tip in either vena cavae or in the left atrium through a patent foramen ovale. TEE confirmed that the inflow cannula did not abut the walls of the RA in our patient, and that it was not advanced too far into the superior vena cava or across the tricuspid valve (TV) (Video 1, Clip 4, http://links.lww.com/AA/A683). No turbulence was noted by CFD in the proximity of the inflow cannula opening confirming unobstructed drainage into the cannula.

TEE evaluation of the pRVAD should include assessment of all cardiac structures that could be affected by the pRVAD cannulae. TV leaflets can be tethered, displaced, or, less commonly, damaged as a consequence of pRVAD outflow cannula positioning and manipulation. If resulting TR is severe, this can compromise antegrade RV output and potentially hinder the ability to wean from pRVAD support. If significant TR noted on TEE is thought to be related to tethering or displacement of TV leaflets by the cannulae, repositioning the cannulae can sometimes reduce TR. Surgical repair of the TV should be considered at the time of pRVAD explant if severe TR persists after the pRVAD outflow cannula is removed. The surgical approach to TV repair will depend on the mechanism of TR.6

Although not the primary focus of this article, RV function should be carefully evaluated before and after pRVAD explantation. This includes qualitative assessment of RV free wall function and interventricular septal motion and, ideally, at least 2 recommended quantitative echocardiographic methods for evaluating RV systolic performance.7 Our patient underwent multiple transthoracic echocardiographic evaluations before presenting to the OR. These studies demonstrated improved RV function with reduced pRVAD flows. Intraoperatively, the RV demonstrated good free wall contractility without bowing of the interventricular septum toward the left ventricle, both after discontinuing pRVAD outflow and after pRVAD explant (Video 2, Clips 1 and 2, http://links.lww.com/AA/A684). Should RV dysfunction persist or recur after cessation of pRVAD support, plans for intrathoracic RVAD implantation for longer-term RV support should be made.

For a summary of key steps in evaluating the proper position of pRVAD cannulae, please refer to Table 1.

Table 1
Table 1:
Summary of Key Steps for Transesophageal Echocardiograpy

Clinician’s Key Teaching Points

By Martin M. Stechert, MD, Nikolaos J. Skubas, MD, FASE, and Martin J. London, MD

  • A right ventricular assist device (RVAD) is used to support the recovery of right ventricular (RV) function. Optimal performance of an RVAD mandates proper position of the cannulae. The inflow cannula is positioned inside the right atrium and the outflow cannula in the main pulmonary artery, most often accessed via the femoral veins.
  • The right atrial inflow cannula is imaged in the midesophageal (ME) 4-chamber or transgastric RV inflow views. Migration of the right atrial inflow cannula will impair the proper unloading of the RV. It should not traverse the tricuspid valve or migrate into either of the vena cavae or potentially into the left atrium via a patent foramen ovale. The pulmonary artery outflow cannula traverses the pulmonic valve and is imaged in the ME RV inflow–outflow. The distal end should be 2 cm deep inside the pulmonary artery. Its retrograde migration may result in the partial or entire percutaneous right ventricular assist device (pRVAD) volume entering the RV, while anterograde migration may cause diminished pRVAD performance and could possibly result in perforation of a pulmonary artery branch.
  • In this case, the inflow cannula was inserted via an alternate site, the right internal jugular vein, and 2-dimensional imaging verified its proper position. Color flow Doppler imaging demonstrated the presence of only mild pulmonic regurgitation, verifying that the side holes of the distal outflow cannula were inside the main pulmonary artery. Examination of the tricuspid valve did not reveal any anatomic or functional abnormalities potentially related to cannula placement.
  • Any deterioration of RV function warrants consideration of cannulae malposition and should prompt an echocardiographic examination of the cannulae location.

DISCLOSURES

Name: Anna K. Kowalczyk, MD.

Contribution: This author helped prepare the manuscript, figures, and videos.

Attestation: Anna Kowalczyk approved the final manuscript.

Name: K. Annette Mizuguchi, MD, PhD, MMSc.

Contribution: This author helped prepare the manuscript, figures, and videos.

Attestation: K. Annette Mizuguchi approved the final manuscript.

Name: Gregory S. Couper, MD.

Contribution: This author helped prepare the manuscript, figures, and videos.

Attestation: Gregory Couper approved the final manuscript.

Name: Jue Teresa Wang, MD.

Contribution: This author helped prepare the manuscript, f igures, and videos.

Attestation: Jue Wang approved the final manuscript.

Name: Amanda A. Fox, MD, MPH.

Contribution: This author helped prepare the manuscript, figures, and videos.

Attestation: Amanda Fox approved the final manuscript.

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

ACKNOWLEDGMENTS

We would like to acknowledge Mr. James M. Bell (graphic artist, Brigham and Women’s Hospital, Department of Anesthesiology) for his work in creating Figure 2.

REFERENCES

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