Giridhar M. Shivaram

Anti-non-Gal porcine endothelial cell antibodies in acute humoral xenograft rejection of hDAF-transgenic porcine hearts in cynomolgus monkeys.

Abstract:  Background:  Anti‐Galα1–3Gal (Gal) antibodies play a major role in hyperacute rejection and acute humoral xenograft rejection (AHXR) in porcine‐to‐nonhuman primate transplantation. The role of anti‐non‐Gal antibodies in AHXR is less well defined.

Standardized Outcome and Reporting Measures in Pediatric Head and Neck Lymphatic Malformations

Objective To develop general and site-specific treatment effect and outcome measures to standardize the reporting of head and neck lymphatic malformation (HNLM) treatments. Study Design Consensus statement/expert opinion. Setting Multiple tertiary academic institutions. Subjects and Methods The modified Delphi method is an iterative process of collecting expert opinions, refining opinions through discussion and feedback, statistically aggregating opinions, and using these aggregates to generate consensus opinion in the absence of other data. The modified Delphi method was used by a multi-institutional group of otolaryngology and interventional radiology experts in the field of vascular anomalies to formulate a list of recommended reporting outcomes for the study and treatment of head and neck lymphatic malformations. Results Through 3 rounds of iteration, 10 expert panelists refined 98 proposed outcome measures and 9 outcome categories to a final consensus set of 50 recommended outcome measures in 3 global categories (general, demographics, and treatment complications) and 5 site-specific categories (orbit, oral cavity, pharynx, larynx, and neck). Conclusions We propose the first consensus set of standardized reporting measures for clinical and treatment outcomes in studies of HNLMs. Consistent outcome measures across future studies will facilitate comparison of treatment options and allow systematic review. We hope that these guidelines facilitate the design and reporting of subsequent HNLM studies.

Novel early response genes in osteoblasts exposed to dynamic fluid flow

Cyclic mechanical loads applied to the skeleton from habitual physical activity result in increased bone formation. These loads lead to dynamic pressure gradients and oscillatory flow of bone interstitial fluid, which, in turn, exposes cells resident in the bony matrix to oscillatory fluid shear stress. Dynamic fluid flow has previously been shown to be a potent anabolic stimulus for cultured osteoblasts. In this study, we used cDNA microarrays to examine early phase, broad-spectrum gene expression in MC3T3-E1 osteoblasts in response to physical stimulation. RNA was harvested at 30 min and 1 h post-stimulation. RNA was used for microarray hybridization as well as subsequent reverse transcription polymerase chain reaction (RT-PCR) validation of expression levels for selected genes. Microarray results were analysed by both functional and expression profile clustering. We identified a small number of genes at both the 30 min and 1 h timepoints that were either upregulated or downregulated with flow compared to no-flow control by twofold or more. From the group of genes upregulated at 30 min, we selected nine for RT-PCR confirmation. All were found to be upregulated by at least twofold. We identify a novel set of early response genes potentially involved in mediating the anabolic response of MC3T3 osteoblasts to flow, and provide functional groupings of these genes that may shed light on the relevant mechanosensory pathways involved.

Benefits and risks of protocol biopsies in pediatric renal transplantation

Protocol biopsies are defined as sampling of allograft tissue at predetermined times regardless of function. This procedure can be justified due to the lack of non-invasive methods to reliably diagnose rejection (acute or subclinical). Changes in creatinine are not seen with subclinical rejection or early acute rejection and do not always correlate with efficacy of treatment. Parents and providers are still hesitant to pursue protocol biopsy due to the potential complications and lack of definitive evidence of a benefit from doing this procedure. Importantly, the rate of transplant renal biopsy complications requiring additional intervention is low. It is unclear if detection and treatment of subclinical rejection detected on protocol biopsy will lead to improved graft survival. Our goal is to review the literature on this topic and share some of the experience in our center. Definition, indications, and complications of diagnostic transplant renal biopsies are not included in this review.

Pediatric liver transplant portal vein anastomotic stenosis: Correlation between ultrasound and transhepatic portal venography

The objective of this study was to determine which transabdominal ultrasound parameters correlate with portal vein stenosis (PVS) on percutaneous transhepatic portal venography in pediatric liver transplant patients. A retrospective review was performed of percutaneous transhepatic portal venograms performed between 2005 and 2013. The findings were compared to those from ultrasounds performed before venography and at the baseline. Patients were stratified on the basis of the presence of significant PVS (group 1, >50% stenosis; group 2, ≤50% stenosis) on portal venography. Findings were compared to those for age‐matched controls. Twenty portal venograms were performed for 12 pediatric patients. Thirteen of the 20 patients (65%) demonstrated significant PVS (>50%). The mean peak anastomotic velocity (PAV) was 253.6 ± 96 cm/s in group 1, 169.7 ± 48 cm/s in group 2, and 51.3 ± 20 cm/s in the control group. PAV (r = 0.672, P = 0.002) was the only ultrasound variable that correlated with the presence of significant PVS. A receiver operating characteristic curve was generated from PAV and PVS data (area under the curve = 0.75, P = 0.08). A threshold velocity of 180 cm/s led to a sensitivity of 83% and a specificity of 71% in predicting significant PVS on portal venography. At the baseline, the mean PAV was 155.8 ± 90 cm/s for group 1 and 69.5 ± 33 cm/s for group 2 (P = 0.08); for control subjects, it was 78.9 ± 53 cm/s (P = 0.06). PAV is the only measured ultrasound parameter that correlates with significant PVS on portal venography in pediatric liver transplant patients. An elevated baseline PAV may increase the risk of developing PVS. Liver Transpl 21:547–553, 2015.

Emergent embolization of a ruptured splenic artery aneurysm complicating Menkes disease

We report a 7-year-old boy with Menkes disease complicated by rupture of a large splenic artery aneurysm. The aneurysm was successfully embolized with microcoils and n-butyl cyanoacrylate. Further angiographic evaluation revealed marked tortuosity of mesenteric and lower extremity vasculature, including the femoral arteries bilaterally, without aneurysm formation. The patient has since been evaluated annually with computed tomography angiography and there have been no additional vascular complications of his disease during 3-year follow up.

An Interventionalist’s Guide to Hemoptysis in Cystic Fibrosis

Massive hemoptysis occurs in a minority of patients with cystic fibrosis, with an annual incidence of 1%. Although rare, massive hemoptysis can be a severe and potentially fatal complication of this disease. Beyond the acute life-threatening event, hemoptysis in patients with cystic fibrosis has been associated with faster decline in lung function, accelerated need for lung transplant, and increased mortality. The bronchial arteries are the culprit vessels in over 90% of cases of hemoptysis. This normally quiescent vascular system undergoes remarkable hypertrophy, collateralization, and angiogenesis before the onset of hemoptysis, introducing numerous pitfalls for the interventionalist. However, in experienced hands, bronchial artery embolization is a safe and potentially lifesaving therapy. Preprocedural noninvasive imaging, specifically computed tomographic angiography, has been repeatedly validated for helping to localize the likely site of bleeding, characterizing pertinent arterial anatomy, and promoting efficient and effective intervention; it has been recommended for all stable patients with hemoptysis. Success in the angiographic suite requires a thorough understanding of normal and variant bronchial arterial anatomy, appropriate patient selection, and a meticulous embolization technique. A meticulous approach to imaging and intervention, conscientious of both visualized and nonvisualized collateral pathways and nontarget vessels, can minimize potentially devastating complications. This review summarizes the current literature, modern procedural techniques, and emerging controversies, serving to guide an evolving approach to management of patients with cystic fibrosis and hemoptysis. ©RSNA, 2018.

Interventional Radiology Services for Vascular Anomalies: An Update

Interventional radiology procedures for the treatment of vascular anomalies have evolved over the last several years. Specifically, newer procedural imaging techniques and embolization materials have expanded the range of options for minimally invasive treatment. For example, preoperative embolization of venous malformations with n-BCA glue to aid in surgical resection has emerged as an effective alternative to traditional percutaneous sclerotherapy (Tieu et al, Otolaryngol Head Neck Surg 48:678–684, 2013). Imaging techniques have also evolved, for example, with the use of cone beam computed tomography (CBCT) adjunctively with angiography. This chapter will discuss these recent advances in interventional radiology for the treatment of vascular anomalies.

Adjustable diameter TIPS in the pediatric patient: the constrained technique

Placement of transjugular intrahepatic portosystemic shunt (TIPS) is necessary in children with portal hypertension complicated by variceal bleeding or ascites. However, placement of adult-sized endografts may be problematic due to the smaller anatomy of pediatric patients. On the other hand, placement of fixed diameter smaller stents have the corresponding problem of not accommodating future growth of the child. We describe a novel method to create an adjustable diameter TIPS as a technical solution to these problems. In this technique, a balloon expandable bare metal stent is placed concentrically around the ePTFE TIPS endograft, creating an intentional narrowing in the shunt diameter than can be expanded with balloon dilation at future procedures as needed. This allows for optimal calibration of shunt hemodynamics according to the childs growth and prevents the potential need for placement of additional shunts or technically challenging TIPS reduction procedures.

Pediatric liver transplant portal vein anastomotic stenosis: Correlation between ultrasound and transhepatic portal venography: Pediatric Portal Vein Anastomotic Stenosis

The objective of this study was to determine which transabdominal ultrasound parameters correlate with portal vein stenosis (PVS) on percutaneous transhepatic portal venography in pediatric liver transplant patients. A retrospective review was performed of percutaneous transhepatic portal venograms performed between 2005 and 2013. The findings were compared to those from ultrasounds performed before venography and at the baseline. Patients were stratified on the basis of the presence of significant PVS (group 1, >50% stenosis; group 2, ≤50% stenosis) on portal venography. Findings were compared to those for age‐matched controls. Twenty portal venograms were performed for 12 pediatric patients. Thirteen of the 20 patients (65%) demonstrated significant PVS (>50%). The mean peak anastomotic velocity (PAV) was 253.6 ± 96 cm/s in group 1, 169.7 ± 48 cm/s in group 2, and 51.3 ± 20 cm/s in the control group. PAV (r = 0.672, P = 0.002) was the only ultrasound variable that correlated with the presence of significant PVS. A receiver operating characteristic curve was generated from PAV and PVS data (area under the curve = 0.75, P = 0.08). A threshold velocity of 180 cm/s led to a sensitivity of 83% and a specificity of 71% in predicting significant PVS on portal venography. At the baseline, the mean PAV was 155.8 ± 90 cm/s for group 1 and 69.5 ± 33 cm/s for group 2 (P = 0.08); for control subjects, it was 78.9 ± 53 cm/s (P = 0.06). PAV is the only measured ultrasound parameter that correlates with significant PVS on portal venography in pediatric liver transplant patients. An elevated baseline PAV may increase the risk of developing PVS. Liver Transpl 21:547–553, 2015.