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Direct Ultrasound of the Pulmonary Artery Helps
Diagnose a Rare Cause of Right Ventricular Failure
After Heart Transplantation: A Case Report
John S. McNeil, MD,* Si M. Pham, MD,† and Julie L. Huffmyer, MD*
Pulmonary artery anastomosis stenosis is a rare cause of right ventricular failure after orthotopic heart transplantation. In this case report, direct ultrasound of the pulmonary artery helped
diagnose stenosis at a location not visible on transesophageal echocardiography or even with
standard epicardial ultrasound views. It is important to evaluate all vascular anastomoses after
heart or lung transplantation because surgical revision of these lesions is facile, but if left undiagnosed, significant morbidity or mortality is likely. (A&A Case Reports. 2017;XXX:00–00.)
A
cute heart failure after orthotopic heart transplantation is common, and the thin-walled right ventricle
(RV) is often involved, particularly when the recipient has preexisting pulmonary hypertension. If no secondary cause of dysfunction can be identified, then it is deemed
primary graft failure (PGF), which is associated with ischemia-reperfusion injury.1 This is a diagnosis of exclusion, so
every effort should be made to rule out specific causes, such
as rejection, ischemia, or surgical error, because many can be
reversed, resulting in improvement of function. We present
a case report of a rare cause of RV dysfunction after heart
transplantation that was diagnosed by using ultrasound in
an unconventional manner.
A written Health Insurance Portability and Accountability
Act authorization to use/disclose existing protected health
information was obtained for use of this case report and
images.
DESCRIPTION OF THE CASE
A 25-year-old man with dilated nonischemic cardiomyopathy underwent orthotopic bicaval heart transplantation. The
transplanted RV had a reduced ejection fraction immediately after weaning off bypass, necessitating venous-arterial
extracorporeal membrane oxygenation (ECMO) support
via the femoral vessels. When a cause for the dysfunction
could not be determined, he was diagnosed with PGF and
was unable to be weaned off ECMO for days. Despite the
patient’s large size (>100 kg), his native pulmonary artery
(PA) was small and the donor PA was comparatively large,
thus the anastomosis of the donor and recipient PA was surgically challenging. The proximal PA appeared normal on
transesophageal echocardiography (TEE) performed during
the transplantation; however, the anastomosis could not be
visualized due to its anterior location as well as the position
From the *Department of Anesthesiology, University of Virginia School of
Medicine, Charlottesville, Virginia; and †Department of Surgery, University
of Maryland School of Medicine, Baltimore, Maryland.
Accepted for publication September 7, 2017.
Funding: None.
The authors declare no conflicts of interest.
Address correspondence to John S. McNeil, MD, Department of Anesthesiology, University of Virginia Health System, PO Box 800710, Charlottesville,
VA 22908. Address e-mail to jsm6j@virginia.edu.
Copyright © 2017 International Anesthesia Research Society
DOI: 10.1213/XAA.0000000000000656
of the transplanted heart in the chest cavity. On postoperative day 7, transthoracic echocardiography under reduced
ECMO flow showed preserved left ventricular function
with moderate-severe RV dysfunction, moderate tricuspid
regurgitation, and trace pulmonary insufficiency.
On postoperative day 8, the patient presented for nonurgent evacuation of mediastinal hematoma. TEE imaging of
the PA remained challenging, but the anastomosis appeared
stretched to the surgeon, so a Philips L15-7io linear transducer (Philips Medical Systems, Andover, MA) was used
to image the PA directly. The standard RV outflow tract
view, which is obtained by placing the transducer on the
RV outflow tract and aiming the transducer probe toward
the patient’s left shoulder, was insufficient. We therefore
advanced the probe distally along the PA until the stenotic
anastomosis was detected. Sharp cephalad angulation of
the probe was required to obtain clear images.
Long-axis imaging showed stenosis at the anastomotic
site (Figure 1) with turbulent flow (Figure 2). A single-lumen
central line catheter was inserted directly into the RV outflow
tract and advanced into the PA. Under direct ultrasound
visualization, with ECMO flow reduced to below 1 L/min,
the catheter was advanced past the anastomosis, and blood
pressure was transduced; this was repeated proximal to the
stenosis. The pullback gradient measured 10 mm Hg. The
patient was transitioned to full cardiopulmonary bypass,
and the anastomosis was redone using a triangular 1.5 ×
1 cm bovine pericardial patch graft. RV function improved
such that the patient was weaned to femoral venovenous
ECMO, which was required due to pulmonary edema.
Postrepair TEE showed normal left ventricular function and
mildly depressed RV function. The patient was then transported back to the intensive care unit with minimal inotropic
support, and without the diagnosis of PGF.
DISCUSSION
PA anastomosis stenosis is diagnosed when the anastomotic
diameter is <75% of the pre- and postanastomotic vessel
diameters.2 There are no standard values for gradients indicating severity. The pullback gradient measured in this case,
10 mm Hg, may seem insignificant but must be interpreted
in the setting of a depressed RV temporarily not receiving
ECMO support. Measuring the pre- and postanastomotic
vessel diameters with direct ultrasound is straightforward
and can be performed in either short- or long-axis view. The
XXX 2017 • Volume XXX • Number XXXcases-anesthesia-analgesia.org
1
Copyright © 2017 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
Table. Suggested Classification Scheme
for Posttransplant Vascular Anastomotic
Complications4
Type
Description
I
Kinking of the anastomosis caused by excessive length of the
vessel
II
Kinking of the anastomosis due to orientation; may result from
inversion of the donor vessel with respect to recipient
III
True stricture caused by excess tightening of suture line or
misplacement of suture
IV
Intraluminal flow obstruction secondary to thrombosis (IVa) or
dissection (IVb)
V
Flow obstruction due to extraluminal compression or mass
Figure 1. Direct surface view of the PA in long axis; the stenotic
anastomosis is visible on the left side of the image. The ascending
aorta is visible in the center of the image in short axis. PA indicates
pulmonary artery.
Figure 2. Direct surface view of the PA in long axis with Doppler
color flow. The ascending aorta is visible in the center of the clip
in short axis. In both images, the pulmonary artery and ascending
aorta appear smaller than would be expected; this was likely related
to the clotted blood and edema that were present in the chest, which
may also explain the echogenic area surround the aorta. PA indicates pulmonary artery.
anastomosis itself, however, is often difficult to measure
and may require averaging several different measurements
in long axis. Radiographic imaging (computed tomography
or angiography) can also be helpful and may better differentiate between thrombus and stenosis.
RV failure due to an iatrogenic stenotic lesion in the PA is
a rare but potentially devastating complication after heart or
lung transplant.3 The donor artery distal to a stenotic anastomosis is also at risk for kinking, which can further limit
flow. Although there are no formal classification guidelines
for vascular anastomotic complications, some high-volume
lung transplant centers have devised their own diagnostic
criteria, e principles of which are similar to heart transplant
(Table).4 The stenosis in the described case was likely due
to kinking and malorientation resulting from inversion of
the donor vessel with respect to the recipient (type II) and
related to the discrepancy in PA sizes mentioned above.
2 cases-anesthesia-analgesia.org
Careful echocardiographic analysis of both right and left
atrial inflow and ventricular outflow anastomotic sites for
evidence of turbulent flow or flow obstruction is essential.
Direct ultrasound is most commonly used in adults
to scan the ascending aorta (epiaortic) for calcifications
before aortic cannulation and/or aortic cross-clamping.
The American Society of Echocardiography/Society of
Cardiovascular Anesthesiologists guidelines prescribe 5
standard epiaortic views5 and 7 standard epicardial views6
with which echocardiographers should be familiar. Direct
cardiac or vascular ultrasound images, particularly of anterior structures easily accessible on the surgical field after
sternotomy, can often be superior to standard TEE images
due to their higher frequency (typical linear probe is 15–7
MHz) as compared to standard phased array TEE probes
(7–4 MHz).
Surface ultrasound imaging of the PA is not routinely
performed in adults, although it is a safe and simple option,
particularly when TEE is contraindicated or inadequate.
Potential indications for direct imaging of the PA include
the following: (1) positioning of a PA catheter or stent; (2)
evaluation for posttransplant (heart or lung) vascular anastomoses stenosis; and (3) evaluation for proximal pulmonary embolism. TEE has low sensitivity and specificity
for detection of pulmonary emboli and is mostly limited
to indirect signs: RV dilation and dysfunction, tricuspid
regurgitation, right atrium dilation, and leftward bowing
of the interatrial septum.7 Direct imaging of the PA and its
branches is more commonly done in the adult congenital
and pediatric cardiac surgery population; a review of over a
thousand cases at the Hospital for Sick Children in Toronto
found that it was utilized in nearly 8% of cases.8
In situations where blood flow is being assessed and
Doppler interrogation is desired, some ultrasound transducers may lack capabilities that are available with the
transducers inside TEE or transthoracic echocardiography
probes. Most linear array hockey stick probes, for example,
have color- and pulsed-wave Doppler capabilities but lack
continuous-wave Doppler. Pulsed-wave Doppler will suffice
for normal PA flow, which is around 100 cm/s, but will alias
when measuring stenotic PA flow, which can reach speeds
of up to 3–4 m/s. When using color Doppler, the Nyquist
limit scale should ideally be set higher (50–60 cm/s) than it
was for this case to most accurately capture the higher flow
rates associated with arterial restriction.
In conclusion, RV failure due to PA anastomosis stenosis
is a rare but serious complication after heart transplantation.
A & A CASE REPORTS
Copyright © 2017 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
Direct vascular ultrasound using a high-frequency transducer is a valuable tool that anesthesiologists and surgeons
should be comfortable performing, particularly when TEE
or epicardial imaging is inadequate. E
ACKNOWLEDGMENTS
The authors would like to thank the following people for their help
in preparing the manuscript: Amanda M. Kleiman, MD (Assistant
Professor, Department of Anesthesiology, University of Virginia
School of Medicine, Charlottesville, VA), and Feroze Mahmood
(Professor of Anaesthesia, Harvard Medical School, Boston, MA).
DISCLOSURES
Name: John S. McNeil, MD.
Contribution: This author helped perform the study and write/
revise the manuscript.
Name: Si M. Pham, MD.
Contribution: This author helped perform the study and write/
revise the manuscript.
Name: Julie L. Huffmyer, MD.
Contribution: This author helped write/revise the manuscript.
This manuscript was handled by: Raymond C. Roy, MD.
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Copyright © 2017 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.
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