Vascular Complications of Transplantation: Part 2: Pancreatic Transplants

Vascular complications after solid organ transplantation are not uncommon and may lead to graft dysfunction and ultimately graft loss. A thorough understanding of the surgical anatomy, etiologies, and types of vascular complications, their presentation and the options for management are important for managing these complex patients. This article reviews the basic surgical anatomy, the vascular complications, and endovascular management options of vascular complications in patients with pancreas transplants.     

Imaging in whole organ pancreatic transplants and a multimodality review of its complications

This pictorial review will describe the normal anatomy of whole organ pancreatic transplants and the common surgical variants with which the radiologist should be familiar. Complications may be divided into (1) vascular: arterial occlusion and stenosis, venous thrombosis, pseudoaneurysms and arteriovenous fistulae, (2) parenchymal complications such as pancreatitis and the variety of peripancreatic collections, and (3) enteric complications including leak and fistula formation. The radiologist plays a crucial role in the initial assessment of graft anatomy and perfusion, prompt diagnosis, and increasingly, in the management of complications.     

Multimodality imaging of pancreas-kidney transplants

Simultaneous pancreas-kidney transplant remains a treatment option for patients with insulin-dependent diabetes mellitus type 1, aimed at restoring normoglycemia, alleviating insulin dependency, avoiding diabetic nephropathy, and thereby improving the quality of life. Imaging remains critical in the assessment of these transplant grafts. Ultrasound with Doppler remains the primary imaging modality for establishing baseline assessment of the graft as well as for evaluating vascular, parenchymal, and perigraft complications. Noncontrast MR imaging is preferred over non-contrast CT for evaluation of parenchymal or perigraft complications in patients with decreased renal function, although contrast-enhanced CT/MR imaging may be obtained following multidisciplinary consultation in cases with high clinical and laboratory suspicion for graft dysfunction. Catheter angiography is reserved primarily for therapeutic intervention in suspected or confirmed vascular complications. An understanding of the surgical techniques and imaging appearance of a normal graft is crucial to identify potential complications and direct timely management. This article provides an overview of surgical techniques, normal imaging appearance, as well as the spectrum of imaging findings and potential complications in pancreas-kidney transplants.     

A review of sonographic evaluation of renal transplant complications

In this article, we present an overview of renal transplantation with its complications and discuss the abilities and limitations of ultrasound in evaluating these complications. We included renal transplants performed at our institution between 1993 and 2006 and gathered data on more than 1,000 patients who developed graft dysfunction. We analyzed the ultrasound findings in different posttransplant complications and compared our findings with those in published literature. We present this review article that elaborates and categorizes various transplant complications from an ultrasound perspective. Based on imaging evaluation, the complications of renal transplantation can be divided into four major categories: peri-renal, renal parenchymal, renal collecting system, and renal vascular complications. Common complications included acute tubular necrosis, graft rejection, drug nephrotoxicity, hematoma, lymphocele, urinoma, hydronephrosis, and vascular complications. Ultrasound has a key role in identification and management of most of these complications. However, some parenchymal complications may only be diagnosed on renal biopsy. Ultrasound is a very powerful screening tool to assess renal transplant dysfunction and has a primary role in early diagnosis and management of structural and vascular complications, which may need surgical intervention to save the graft.     

Renal Transplant Complications: Diagnostic and Therapeutic Role of Radiology

Kidney was the first and is the most frequently transplanted organ. Despite improved surgical techniques and transplantation technology, complications do occur and, if left untreated, may lead to catastrophic consequences. Renal transplantation complications may be vascular (eg, renal artery and vein stenosis and thrombosis, arteriovenous fistula, and pseudoaneurysms); urologic (eg, urinary obstruction and leak, and peritransplantation fluid collections, including hematoma, seroma, lymphocele, and abscess formation); and nephrogenic, including acute tubular necrosis, graft rejection, chronic allograft nephropathy, and neoplasm. Early diagnosis and treatment of these complications are paramount to prevent graft failure and other significant morbidities to the patients. Radiology plays a pivotal role in the diagnosis and treatment of these complications, with minimally invasive percutaneous techniques. In this article, we reviewed renal transplantation anatomy, a wide range of complications that may occur after renal transplantation surgery, typical imaging appearances of the complications on varies imaging modalities, and percutaneous interventional techniques that are used in their treatment.     

CT angiography of lower extremity vascular bypass grafts

Over the past several years computed tomography (CT) technology has advanced to such a degree that CT angiography (CTA) has become the study of choice at our institution for imaging lower extremity vascular bypass grafts. CTA quickly provides anatomic information about the state of the graft and identifies virtually all forms of bypass graft failure and related complications. Furthermore, detailed vascular anatomy is seen beyond the graft and affords sufficient anatomic detail for surgical revision without the need for other angiographic studies. Although catheter angiography, duplex-ultrasound, magnetic resonance angiography, and nuclear medicine studies all continue to play some role in the evaluation of vascular grafts, they are more often used as problem solving modalities when CTA findings are equivocal. Whereas it was once essential to catheterize directly through a failing bypass graft or pass catheters into the graft from a distant arterial puncture to obtain an angiogram of a failing bypass graft, CTA produces arteriograms with only intravenous contrast administration, a brief visit to the CT scanner, and return to daily activities without catheterization, discomfort, or risk to the bypass conduit.     

Surgery for chronic pancreatitis: cross-sectional imaging of postoperative anatomy and complications

OBJECTIVE: Surgery is increasingly undertaken for intractable chronic pancreatitis. We evaluated the postsurgical anatomy and complications of surgical options including Whipple, Puestow, Frey's, and Beger's procedures. CONCLUSIONS: Knowledge of postsurgical anatomy is important to avoid misdiagnosing expected anatomy as complications on CT examinations. It is important to carefully assess the upper abdominal arteries to detect subtle but potentially lethal complications.     

Coronary artery bypass graft imaging with 256-slice MDCT: surgical concepts,current techniques,and interpretation

Multidetector computed tomography (MDCT) scanners with current equipment allow for a rapid and robust noninvasive assessment of coronary artery bypass graft (CABG) anatomy and patency. With both appropriate expertise in MDCT techniques and knowledge in CABG imaging interpretation, radiologists should play an important and active role in the postoperative care of patients with bypass grafts. In this pictorial essay, we review the MDCT techniques and anatomy relevant to CABG imaging, interpretation pitfalls, some basic and advanced surgical designs, as well as postoperative graft complications in patients with CABG, with clinical illustrations from our local experience.     

Interventional neuroradiology of the head and neck

Interventional neuroradiology procedures are a valuable asset in the diagnosis, treatment, and surgical management of various disorders affecting the extracranial head and neck. A detailed understanding of cross-sectional and vascular anatomy and an awareness of potential collateral pathways between extracranial and intracranial vessels are essential for ensuring safe and successful procedures. With the use of high-quality imaging and a meticulous technique, the incidence of major complications is extremely low.     

Postliver transplantation vascular and biliary surgical anatomy

Imaging and management of postliver transplantation complications require an understanding of the surgical anatomy of liver transplantation. There are several methods of liver transplantation. Furthermore, liver transplantation is a complex surgery with numerous variables in its 4 anastomoses: (1) arterial anastomosis, (2) venous inflow (portal venous) anastomosis, (3) venous outflow (hepatic vein, inferior vena cava, or both) anastomosis, and (4) biliary/biliary-enteric anastomosis. The aim of this chapter is to introduce the principles of liver transplant surgical anatomy based on anastomotic anatomy. With radiologists as the target readers, the chapter focuses on the inflow and outflow connections and does not detail intricate surgical techniques or intraoperative maneuvers, operative stages, or vascular shunting.     

Update: Complications and management of infrarenal EVAR

Endovascular aortic aneurysm repair (EVAR) is now an established technique for treating many patients with infrarenal abdominal aortic aneurysm. Familiarity with the complications associated with this technique and understanding treatment options are crucial for the lifelong performance of stent graft.This pictorial review article describes the currant role of different imaging modalities in surveillance and discusses the complications and its management strategies.     

Magnetic resonance imaging in the complications of kidney transplantation

Kidney transplantation is currently the treatment of choice in most patients with end-stage chronic renal failure owing to the excellent results in terms of both graft and patient survival. However, surgical complications are still very frequent. Although urological (stricture, urinary fistulas, vesico-ureteral reflux) and lymphatic complications (lymphocoele) have a high incidence, they only rarely lead to graft loss. By contrast, vascular complications (stenosis, arterial and venous thrombosis, arterio-venous fistulas, pseudoaneurysms) are relatively rare, but potentially serious and may affect graft survival. Finally, medical complications such as acute tubular necrosis (ATN), rejection and de novo neoplasms may also arise in kidney transplantation. The purpose of this pictorial review is to illustrate the increasingly significant contribution of magnetic resonance angiography (MRA) in the management of complications of kidney transplantation, and emphasise how this method should now be considered a mandatory step in the diagnostic workup of selected cases. Moreover, the application and role in this setting of new magnetic resonance imaging (MRI) techniques, such as diffusion-weighted and blood oxygen level-dependent (BOLD) MRI, are also discussed.     

Evaluation and complications of direct graft puncture in thrombolysis and other interventional techniques

Purpose: To evaluate the value and complications of direct graft puncture in conducting interventional procedures in synthetic vascular bypass grafts. Methods: We retrospectively reviewed 65 direct graft punctures in 50 patients undergoing a variety of interventional vascular procedures. In two patients the grafts were found to be infected and the procedures abandoned. Results: Complications encountered included hematomas that did not require treatment in three patients, and four hematomas requiring surgical drainage. One graft became infected (despite prophylactic cefuroxime), after three consecutive punctures over a 10-day period for a variety of interventions. All the patients who developed hematomas had undergone pharmacological thrombolysis. Conclusion: Direct graft puncture is a relatively safe technique, with a minimal risk of infection and hemostatic complications attributable to thrombolysis. In 31 of the 41 patients undergoing successful thrombolysis, additional percutaneous procedures were undertaken, and these were facilitated by the direct graft puncture route.     

Multidetector CT in pre- and post-operative evaluation of living-related liver transplantation

Objective

To assess the role of multi-detector CT (MDCT) in the pre and post operative evaluation of both potential donors and recipients for living related liver transplantation (LRLT).

Material and Methods

This prospective study included 26 patients for LRLT and their corresponding donors. For preoperative assessment, all subjects were evaluated by triphasic CT abdomen. CT angiography (CTA) with 3D reconstruction and CT volumetry was additionally done for donors. CT findings were compared to surgical results as gold standard reference. In post-operative evaluation, CT abdomen was performed at least once after transplantation for all recipients and for indicated donors. CTA was done for indicated recipients when US findings were inconclusive.

Results

No statistically significant difference was found between CT volumetry and intraoperative findings. Compared to surgical findings, MDCT identified hepatic arterial and portal venous anatomy with 100% sensitivity and specificity, while for hepatic venous anatomy; it showed sensitivity and specificity of 85.7% and 84.2%. Biliary complications and fluid collections were the commonest in recipients and donors respectively.

Conclusion

MDCT is a single comprehensive non-invasive and accurate imaging modality for preoperative evaluation of liver parenchyma, hepatic vascular anatomy and graft volume and postoperative complications in donors and recipients of LRLT.     

Angiography of segmental pancreatic transplants

Arteriography was routinely performed in patients with suspected vascular complications after pancreas transplantation. Dysfunction of the grafts was suggested by 99mTc-DTPA scanning and metabolic tests. Thirty arteriograms obtained in 25 patients were evaluated. Nineteen conventional film angiograms and 11 intraarterial DSA were performed. Five different angiographic patterns were observed: normal vascular anatomy, low-flow phenomenon, arterial or venous thrombosis, and venous neovascularity. On the basis of the angiographic findings, various reasons for graft failure were identified. Recipient venous collaterals or well-functioning grafts without angiographically detectable blood supply were observed in 9 cases, and must be considered to represent neovascularisation by donor and recipient vessels.     

Coronary artery bypass grafts and MDCT imaging: what to know and what to look for

Multi-detector row CT (MDCT) scanners with high spatial and temporal resolutions are now available and are increasingly used for non-invasive assessment of vascular disease, including coronary arteries and coronary artery bypass grafts (CABG). Follow-up of patients who have previously undergone surgical revascularization for coronary artery disease is nowadays one of the main applications of MDCT. Thanks to the continuous technical evolution of the CT scanners, it is now possible to scan the heart and the full anatomic extent of grafts with sub-millimeter slice-thickness within a single breath-hold. In the evaluation of these patients, it is important for the radiologist to be familiar with the different types of grafts and surgical techniques to know the main characteristics of each graft type and what to look for in the assessment of a patient who has undergone coronary artery surgical revascularization. This review summarizes some surgical aspects, the biological characteristics of conduits, and the main technical MDCT features, and describes the CABG anatomy together with some typical CT findings.     

Loop arteriovenous graft of the chest wall as a viable option for dialysis

The search for a reliable, complication-free vascular access is crucial among dialysis patients. The creation of a long-term access site for hemodialysis is dependent on several factors that mandate forming a life-plan for dialysis access, with upper extremity vascular access being the preferred route. However, complications including poor maturation, venous anastomosis lesions, and thrombosis are all associated with poor survival of these accesses. As a result, numerous patients within the dialysis population have exhausted access sites in the upper and lower extremities, requiring the search for other access options including chest wall arteriovenous graft (AVG). However, limited data is available about the outcomes of these chest wall grafts. Here, we describe two 62-year-old female dialysis patients who exhausted other dialysis access sites and subsequently underwent arteriovenous loop graft of the chest wall that connected the axillary artery with the ipsilateral axillary vein. These AVGs remained functional during the follow up period. This report highlights the viability of chest wall AVG access in the unique subset of hemodialysis patients who exhausted all other access sites.     

US vascular mapping before hemodialysis access placement

PURPOSE: To prospectively assess the effect of preoperative ultrasonographic (US) mapping on surgical selection, placement of arteriovenous fistulas (AVFs) and grafts, and negative surgical exploration rates. MATERIALS AND METHODS: US assessment of the upper extremity arterial and venous anatomy was performed in 70 patients with chronic renal failure before surgical evaluation. The surgeon documented the planned access procedure, which was based on physical examination results, and then reviewed the US preoperative mapping report. The surgical procedure and outcome were recorded. RESULTS: Fifty-two of the 70 patients who underwent mapping had vascular access placement. Preoperative US mapping resulted in a change in the planned surgical procedure in 16 (31%) of the 52 patients. An AVF rather than the planned graft was placed in eight (15%) patients. The AVF placement rate increased from 32% (126 of 395 patients) to 58% (30 of 52 patients). Unsuccessful surgical explorations decreased from 11% (28 of 256) to 0%. CONCLUSION: Preoperative US mapping before hemodialysis access placement can result in a change in surgical management, with an increased number of AVFs placed and an improved likelihood of selecting the most functional vessels preoperatively. Further study is needed to determine longer term outcomes.     

Imaging and management of complications of open surgical repair of abdominal aortic aneurysms

Open repair is still considered the reference standard for long-term repair of abdominal aortic aneurysms (AAA). In contrast to endovascular aneurysm repair (EVAR), patients with open surgical repair of AAA are not routinely followed up with imaging. Although complications following EVAR are widely recognized and routinely identified on follow-up imaging, complications also do occur following open surgical repair. With frequent use of multi-slice computed tomography (CT) angiography (CTA) in vascular patients, there is now improved recognition of the potential complications following open surgical repair. Many of these complications are increasingly being managed using endovascular techniques. The aim of this review is to illustrate a variety of potential complications that may occur following open surgical repair and to demonstrate their management using both surgical and endovascular techniques.     

Diversion ahead: imaging appearance of urinary diversions and reservoirs

The imaging appearance of urinary diversion is determined by the indication and type of surgical procedure performed. These patients often undergo an imaging follow-up to detect complications or recurrence. Understanding the postoperative anatomy and early detection of complications are keys to adept interpretation of radiological evaluation of urinary reservoirs. The purpose of following review is to offer a brief account of commonly used surgical techniques, relevant anatomy, and concise overview of the imaging techniques for evaluation of the urinary diversions and features of their complications.