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 email@example.com. 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. REFERENCES 1. Iyer A, Kumarasinghe G, Hicks M, et al. Primary graft failure after heart transplantation. J Transplant. 2011;2011:175768. 2.Ferretti G, Boutelant M, Thony F, Carpentier F, Pison C, Guignier M. Successful stenting of a pulmonary arterial stenosis after a single lung transplant. Thorax. 1995;50:1011–1012. 3. Gieraerts R, Schertz C, Ghignone M. 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Guidelines for performing a comprehensive epicardial echocardiography examination: recommendations of the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. Anesth Analg. 2007;105:22–28. 7. Rosenberger P, Shernan SK, Body SC, Eltzschig HK. Utility of intraoperative transesophageal echocardiography for diagnosis of pulmonary embolism. Anesth Analg. 2004;99:12–16. 8. Muhiudeen IA, Roberson DA, Silverman NH, Haas G, Turley K, Cahalan MK. Intraoperative echocardiography in infants and children with congenital cardiac shunt lesions: transesophageal versus epicardial echocardiography. J Am Coll Cardiol. 1990;16:1687–1695. XXX 2017 • Volume XXX • Number XXXcases-anesthesia-analgesia.org 3 Copyright © 2017 International Anesthesia Research Society. Unauthorized reproduction of this article is prohibited.