Site Of Shunt Research Articles

Can diffuse reflectance spectroscopy identify shuntodynia in pediatric hydrocephalus patients?

Shuntodynia is patient reported pain at the site of the implanted ventriculoperitoneal (VP) shunt. Pediatric hydrocephalus requiring shunt placement is a chronic and prevalent standard of care treatment and requires lifetime management. Shuntodynia is a subjective measure of shunt dysfunction. Quantitative, white-light tissue spectroscopy could be used to objectively identify this condition in the clinic. Pediatric subjects were recruited for optical sensing during routine clinical follow-up visits, post-VP shunt implantations. Acquired optical signals were translated into skin-hemodynamic signatures and were compared between subjects that reported shuntodynia versus those that did not. Diffuse reflectance spectroscopy (DRS) measurements were collected between 450 and 700nm using a single-channel fiber-optical probe from () patients. Multiple reflectance spectra were obtained by the attending physician from regions both proximal and distal to the VP shunt sites and from a matched contralateral site for each subject. Acquired reflectance spectra were processed quantitatively into functional tissue optical endpoints. A two-way, repeated measures analysis of variance was used to assess whether and which of the optical variables were statistically separable, across subjects with shuntodynia versus those without. Analyses indicated that intrapatient differences in vascular oxygen saturation measured between shunt sites relative to that obtained at the scar or contralateral sites was significantly lower in the pain group. We also find that the total hemoglobin concentrations at the shunt site were lowest relative to the other sites for subjects reporting pain. These findings suggest that shuntodynia pain arises in the scalp tissue around the implanted shunts and may be caused due to hypoxia and inflammation. Optically derived hemodynamic variables were statistically significantly different in subjects presenting with shuntodynia relative to those without. DRS could provide a viable mode in routine bedside monitoring of subjects with VP shunts for clinical management and assessment of shuntodynia.

Vascular Plug-Assisted Retrograde Obliteration (PARTO) of Right Mesorenal Shunt for Hepatic Encephalopathy: An Uncommon Site of a Spontaneous Portosystemic Shunt in Cirrhosis.

Vascular Plug-Assisted Retrograde Obliteration (PARTO) of Right Mesorenal Shunt for Hepatic Encephalopathy: An Uncommon Site of a Spontaneous Portosystemic Shunt in Cirrhosis.

MRI as a one-stop destination for evaluation of CSF shunt malfunction

BackgroundDespite the high-frequency rate of cerebrospinal fluid shunt malfunction, radiological evaluation of CSF shunts has remained deficient, focusing mainly on demonstrating secondary signs of shunt failure rather than evaluating the shunt tube itself. We aimed to study the utility of different MR pulse sequences in evaluating the cranial and abdominal ends of CSF shunts in order to identify the potential cause of shunt failure and its impact on patient management.ResultsTwenty-five patients (18 males, 7 females, median age 2.5 years, IQR 0.75–15) were enrolled in the study, having 28 ventriculo-peritoneal shunts and single ventriculo-gallbladder shunt. The catheter lumen and fine intraventricular septae were only demonstrated in 3D-DRIVE sequences (p < 0.001). Except for three patients (having cranial end-related complications), all patients with cranial and/or abdominal end-related complications received surgery (p < 0.001, positive likelihood and negative likelihood ratios = 7.27, 0.3, respectively, sensitivity = 0.7 and specificity = 0.9). MRI findings (luminal occlusion, disconnection, CSF collection, or migration) were consistent with operative data. There is no significant difference between patients who underwent surgery and those with conservative management, or symptomatic and asymptomatic patients in terms of the prevalence of ventricular dilatation or white matter signal abnormality. The results of the abdomino-pelvic fat-suppressed T2-WI showed excellent agreement with ultrasound findings (Cohen’s Kappa 0.9). Quantitative PC could give insights into CSF dynamics, which depend on the site and cause of shunt malfunction.ConclusionsMRI could be a one-stop destination for evaluating patients with suspected non-acute shunt malfunction. It was found to have clinical relevance in terms of accurately locating the exact site and possible cause of shunt-related complications.

EPEN-07. PATTERNS OF EXTRANEURAL METASTASES IN PEDIATRIC SUPRATENTORIAL EPENDYMOMA: CASE SERIES AND REVIEW OF THE LITERATURE

BACKGROUNDEpendymomas account for 10% of all malignant pediatric intracranial tumors. Standard therapy includes maximal safe surgical resection followed by involved-field radiation. Up to 50% of localized pediatric ependymomas recur. Extraneural metastases at time of recurrence are rarely reported.OBJECTIVETo describe extraneural metastases of pediatric ependymomas.METHODSRetrospective review of patients’ medical records and literature review.RESULTSThree patients with history of locally recurrent, supratentorial ependymoma developed extraneural metastases: one in a cervical lymph node, one with a scalp nodule, and one with a dural lesion. Each extraneural recurrence had similar histologic and molecular features as the initial diagnosis. The cervical lymph node recurrence was treated with multimodal therapy; she is without disease four years later. The isolated scalp nodule occurred at the exit site of a subgaleal drain placed during prior resection. Following nodule resection, he developed additional scalp and lymph node disease and is receiving palliative care. The isolated dural recurrence occurred at the exit site of a ventriculoperitoneal shunt placed following a previous resection. She died of progressive disease 18 months after dural lesion resection. Reports of lymph node, scalp, and dural metastases of ependymomas are exceedingly rare, and outcomes are poor.CONCLUSIONSExtraneural manifestations of ependymoma are rare. Regional seeding from prior surgical procedures may play a role in metastatic spread. Extraneural metastases should be considered in children previously treated for ependymoma who develop local findings even in the absence of CNS relapse. Salvage therapy with curative intent should be considered using a multimodal approach.

Fault-Tolerant Electric Motors with Permanent Magnets and Electromagnetic Shunting

The main contribution of the paper is the analysis of processes and the evaluation of the effectiveness of fault-tolerant PMEM with electro-magnetic winding shunting, including the winding shunt location on the back of the stator magnet guide. This paper presents studies of the electric motors with permanent magnets with turn-to-turn short circuits protection using an electromagnetic shunt. Studies are performed on a low-power electric generator, which is designed to generate electricity on an unmanned aerial vehicle. At the same time, in contrast to the well-known works, two installation sites of an electromagnetic shunt are considered: on the stator's back (this method has been not considered in the literature before). Then the electromagnetic wedge and the most efficient installation site of the electromagnetic shunt are selected. For this task, computer models and experimental samples for both variants are created, whose studies in various operating modes are also given in the paper. According to the research results, recommendations on the use of electromagnetic shunting in electric machines with permanent magnets have been developed.

P105 Shunt migration in ventriculoperitoneal shunting: a comprehensive review of literature

ObjectivesThe mechanical shunt complication- shunt migration is roughly noted in 1 in 1000 patients with shunt. Most of the literature on shunt migration is case reports. In this narrative review we analyze about presentation, complications and management options for each site of shunt migration.DesignNarrative review.SubjectsIn total 239 articles were reviewed in this narrative review which includes a total of 396 shunt migrations.MethodsLiterature search was performed using PubMed Central for all articles containing the term Ventriculoperitoneal shunt migration. All articles published through 2016 were included in this review.ResultsSites of migration were – perforation of the bowel in 139 patients; abdominal wall (57); scrotum (55); chest (32); intracranial (30); cardiac/intravascular (28); genitourinary (15); breast (13); subgaleal (12) and miscellaneous (15).ConclusionsMigration to bowel, heart, intracranial and subgaleal space are associated with 20% chance of shunt dysfunction Any extrusion (irrespective of the site) where the shunt catheter is exposed to the external environment is associated with around 50% chance of shunt infection.

Congenital absence of the portal vein: translated version.

Congenital portosystemic shunt (CPS) is classified into type I (congenital absence of the portal vein) and type II, depending on the presence or absence of the intrahepatic portal vein. Reports still exist on cases in which psychiatric diseases or mental retardation was diagnosed or cases in which diagnosis and treatment are not performed until severe pulmonary complications occur, indicating the need to recognize CPS. Herein, we reviewed epidemiology, etiology, classification, symptom, diagnosis, and treatment based on clinical view points of CPS. For clinical view points, classification according to (1) the presence or absence of the intrahepatic portal venous system (IPVS) and (2) the extrahepatic or intrahepatic of shunt sites, facilitates the understanding of pathophysiological conditions and is useful in selecting a treatment for symptomatic CPS. Radiological and pathological examinations are important in IPVS evaluations, and IPVS evaluations are currently essential to make diagnoses by portography with balloon occlusion and liver biopsy. Symptomatic CPS (hepatic nodular lesions, portosystemic encephalopathy, and pulmonary complications, etc.) is an indication of treatment by shunt closure, but an indication of treatment for asymptomatic CPS is the challenge going forward.

Right upper quadrant abdominal pain due to malposition of the tip of the distal catheter of ventriculoperitoneal shunt

Abstract There are few reports about abdominal pain due to shunt malposition which have been located in right lower quadrant. In this case, we reported a 17-years old boy with history of medulloblastoma surgery and shunt insertion who had severe abdominal pain especially in right upper quadrant without any history of fever, nausea and vomiting and any symptoms of ICP rising. Physical examination revealed a moderate tenderness on the right upper quadrant, but rebound tenderness was absent. Laboratory data including CSF analysis were normal. Plain abdominal films showed the tip of the catheter in the right upper quadrant. Abdominal ultrasound showed a very mild collection at entrance site of shunt in peritoneal cavity. After exploration, there was not any surgical finding. The only thing that could explain the abdominal pain, was location of the tip of distal catheter toward the liver around the falciform ligament. The distal catheter was exited and repositioning performed. After surgery, the abdominal pain of the patients was relieved dramatically. After one year follow up, the patient has not any problem with his shunt.

Vascular access for chronic dialysis using the superficial femoral vein.

We report our experience in using the superficial femoral vein to create hemodialysis (HD) arteriovenous (AV) fistulas. Surgery was performed on six patients (four female, two male). Indications for surgery included previous fistula loss, graft infection and exhaustion of typical shunt sites. The femoral vein was evaluated preoperatively, by Doppler ultrasound, harvested by one long incision on the anteromedial surface of the thigh, followed by suction drainage. In four patients, harvested veins were transplanted in the arm between the brachial artery and axillar vein, followed by an end-to-side anastomosis. In two patients, the venous graft remained on the anterior surface of the thigh. In those patients, they were extended with either a piece of polytetrafluoroethylene (PTFE) graft or the saphenous vein. Follow-up ranged between 14 months and 2 yrs, ensuring proper dialysis. Two patients presented with complications, including lower leg swelling and axillary lymphorrhea, which subsided spontaneously. We recommend this type of AV fistula, especially in difficult cases, where all other classical vascular approaches have been used. However, the procedure is time consuming and requires experience in vascular surgery.

High patency of proximal splenorenal shunt: A myth or reality ? – A prospective cohort study

BackgroundProximal splenorenal shunt (PSRS) is a well-accepted surgical procedure for non-cirrhotic portal hypertension (NCPH). Though a patent shunt is important for good long term outcome, there are very few studies on patency of these shunts. We analysed shunt patency using dynamic computed tomographic (CT) portography and compared it with other modalities. MethodsFrom 2004 to 2014, 50 patients with PSRS were evaluated prospectively for shunt patency using dynamic CT portography, clinical parameters and ultrasound Doppler. ResultsThe causes of NCPH were extrahepatic portal vein obstruction (EHPVO) in 38 patients and non-cirrhotic portal fibrosis (NCPF) in 12 patients. The shunt patency rate using clinical parameters, ultrasound Doppler and dynamic CT portography were 70%, 40% and 60% respectively. Clinical parameters overestimated while ultrasound Doppler underestimated the shunt patency rate. Dynamic portography had 100% correlation with conventional angiography in the five patients when this was done. The site of shunt could be demonstrated convincingly by dynamic CT portography. The shunt patency rate decreased over time. It was 64%, 60% and 43% in <1 year, 1–5 years and >5 years respectively. Our NCPF patients had a greater shunt patency rate compared to EHPVO patients (9/12 vs. 21/38) though the difference was not significant. Only size of the splenic vein had a significant impact on the shunt patency rate on statistical analysis. ConclusionsDynamic CT portography is useful for evaluation of shunt patency. Proximal splenorenal shunts have a high blockage rate which has hitherto not been reported.

Transarterial Coil Embolization of an Abdominal Aortocaval Fistula in a Dog

A 3-year-old, 5 kg, male Toy Poodle with a mast cell tumor on the left pelvic limb was referred to Tokyo University of Agriculture and Technology Animal Hospital for an oncologic evaluation. On physical examination, a continuous bruit was auscultated over the left inguinal region with a palpable thrill. Cardiac auscultation identified a grade II/VI systolic and a grade I/VI diastolic murmur over the mitral and the aortic valves, respectively. No signs of peripheral cyanosis or congestion were noted. On thoracic radiographs, moderate, generalized enlargement of the cardiac silhouette was observed without evidence of pulmonary edema or pleural effusion. Color Doppler echocardiography identified mild pulmonic, mitral, and aortic valve regurgitation. Measurements of the left ventricle (LV) indicated an increased internal diameter with normal LV wall and septal thicknesses, normal fractional shortening and mild left atrial (LA) enlargement, with normal sinus rhythm. Normal mean arterial blood pressure was obtained on the thoracic limb using the oscillometric method. Laboratory test results (complete blood count, serum biochemistry profile, electrolytes, coagulation profile) were within the normal reference ranges. Ultrasonography of the caudal abdomen showed a caudal vena cava (CVC) with a diameter of 24.6 mm (dog <10 kg, reference values 0.65 0.12 mm) at the site of shunt. Color Doppler with simultaneous electrocardiogram showed turbulent flow in the CVC during the arterial phase. Continuous-wave Doppler interrogation showed continuous low-velocity flow with a pulsatile pattern and spectral broadening of Doppler waveform and peak flow velocity of 3 m/s across the aortocaval shunt (Fig 1). Contrast-enhanced computed tomography (CT) was performed under general anesthesia for anatomic evaluation of the arteriovenous shunt. The contrast timing bolus method was used to synchronize image acquisition. Iodinated contrast medium (2 mL/kg of iodine) was injected into the cephalic vein at flow rate of 1 mL/s. After a 20-second delay, the entire abdomen was scanned with a dual-slice spiral CT scanner. Reconstruction was carried out using contiguous images with a slice thickness of 1.0 mm (total of 149 slices). Post imaging processing showed an aortocaval connection by an anomalous vessel (shunt) located caudal to the renal arteries and a saccular dilatation of the CVC elongating in the caudal direction. The major dilatation was observed caudal to the fistula, 2.6-fold greater than the dilatation observed cranial to the fistula (Fig 2A,B). Endovascular repair was performed under general anesthesia that was maintained with isoflurane. The dog was positioned in right lateral recumbency for a cervical left lateral approach and a small incision in the skin was made to access the left common carotid artery. A 4-Fr multipurpose catheter was inserted through a puncture in the artery and advanced over a guide wire. The catheter tip was positioned in the abdominal aorta, cranial to the fistula to perform aortography. A 5-mL bolus injection of iodinated contrast medium showed the contrast medium being diverted from the aorta into the CVC (Fig 3A). Blood flow in the renal arteries was preserved as observed by contrast filling of the arteries and renal excretion. The tip of the catheter then was repositioned into the AVF over a guide wire to deliver the embolization coil, because contrast injection showed that adequate coil deployment could be achieved through the aorta. An embolization coil of 6.5 mm diameter, 5 loops, and 10 cm in length was deployed along the fistula lumen under fluoroscopic guidance. Aortography a few minutes after coil deployment identified residual flow through the fistula (Fig 3B). Residual flow was also observed on Doppler ultrasonography, but the shunt flow velocity had decreased to 1.5 m/s. Recovery from the anesthesia was uneventful. Postoperative mean arterial blood pressure ranged from From the Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan (Nakata, Tanaka, Hamabe, Yoshiyuki, Kim, Suzuki, Aytemiz, Huai-Che, Shimizu, Fukushima). Corresponding author: Ryou Tanaka, DVM, PhD, Department of Veterinary Surgery, Tokyo University of Agriculture and Technology, Saiwai-cho 3-5-8, Fuchu, Tokyo 183-8509, Japan; e-mail: ryo@vet.ne.jp. Submitted May 17, 2013; Revised November 19, 2013; Accepted December 16, 2013. Copyright © 2014 by the American College of Veterinary Internal Medicine 10.1111/jvim.12308 Abbreviations:

High cervical arteriovenous fistulas fed by dural and spinal arteries and draining into a single medullary vein

The authors previously reported a case of complex arteriovenous fistula (AVF) at C-1 with multiple dural and spinal feeders that were linked with a common medullary venous channel. The purpose of the present study was to collect similar cases and analyze their angioarchitecture to gain a better understanding of this malformation. Three such cases, affecting 2 males and 1 female in their 60s who had presented with hematomyelia (2) or progressive myelopathy (1), were treated surgically, and the operative findings from all 3 cases were compared using digital subtraction angiography (DSA) to determine the angioarchitecture. The C-1 and C-2 radicular arteries and anterior and posterior spinal arteries supplied feeders to a single medullary draining vein in various combinations and via various routes. The drainage veins ran along the affected ventral nerve roots and lay ventral to the spinal cord. The sites of shunting to the vein were multiple: dural, along the ventral nerve root in the subarachnoid space, and on the spinal cord, showing a vascular structure typical of dural AVF, that is, a direct arteriovenous shunt near the spinal root sleeve fed by one or more dural arteries and ending in a single draining vein, except for intradural shunts fed by feeders from the spinal arteries. In 2 cases with hemorrhagic onset the drainer flowed rostrally, and in 1 case associated with congestive myelopathy the drainer flowed both rostrally and caudally. Preoperative determination of the shunt sites and feeding arteries was difficult because of complex recruitment of the feeders and multiple shunt sites. The angioarchitecture in these cases was clarified postoperatively by meticulous comparison of the DSA images and operative video. Direct surgical intervention led to a favorable outcome in all 3 cases. A high cervical complex AVF has unique angioarchitectural characteristics different from those seen in the other spinal regions.

Coronary artery to pulmonary artery fistula

Patient: Male, 69Final Diagnosis: Coronary artery to pulmonary artery fistulaSymptoms: Chest painMedication: —Clinical Procedure: Echocardiography • angiography • surgical interventionSpecialty: Cardiology • Cardiac SurgeryObjective:Rare diseaseBackground:A coronary artery fistula is an abnormal communication between a coronary artery and one of the cardiac chambers or a great vessel, so bypassing the myocardial capillary network. They are usually discovered incidentally upon coronary angiography. Clinical manifestations are variable depending on the type of fistula, the severity of shunt, site of shunt, and presence of other cardiac condition.Case Report:We report a 69-year-old man without any previous medical history, who was admitted to our hospital with chest pain. The electrocardiogram (ECG) showed a sinus rhythm with ST depression in V2 to V6 precordial leads. Coronary angiography revealed a coronary artery fistula from left anterior descending coronary artery (LAD) to the main pulmonary artery, right coronary artery blockage and significant stenoses on the LAD and left circumflex artery (LCX).Conclusions:Surgical treatment was chosen because of the total occlusion of the right coronary artery and to relieve of pain to improve quality of life.

Fatal exsanguination from hemodialysis vascular access sites

Exsanguination from hemodialysis vascular sites may cause a rapid death. Due to extensive blood loss at the scene, investigators may initially suspect a homicide or suicide. We reviewed 100 deaths due to hemorrhage from hemodialysis shunt sites. The majority (81%) of these hemorrhages occurred at home and 44% subsequently died at home. Recognition of this medical complication at the scene is important to prevent the dispatch of the crime scene or homicide unit. In these instances, the common causes of kidney failure included hypertensive cardiovascular disease and diabetes mellitus. The manners of death were certified as therapeutic complication (93%), accident (5%), and suicide (2%). These fatal shunt hemorrhages are rapid and large due to their superficial subcutaneous locations and elevated shunt pressures from the arterial-venous anastamosis. The cause of death statement must include the proximate cause of death, which is usually the disease that resulted in kidney failure, if it is known.

Direct Vascular Control Results in Less Physiologic Derangement Than Proximal Aortic Clamping in a Porcine Model of Noncompressible Extrathoracic Torso Hemorrhage

The optimal method of vascular control and resuscitation in patients with life-threatening, extrathoracic torso hemorrhage remains debated. Guidelines recommend emergency department thoracotomy (EDT) with aortic clamping, although transabdominal aortic clamping followed by vascular control and direct vascular control (DVC) without aortic clamping are alternatives. The objective of this study is to compare the effectiveness of three approaches to extrathoracic torso hemorrhage in a large animal model. Adolescent swine (Sus Scrofa) (mean weight = 80.9 kg) were randomized into three groups all of which had class IV shock established by hemorrhage from an iliac artery injury. Group 1: EDT with thoracic aortic clamping (N = 6); group 2: transabdominal supraceliac aortic clamping (SCC; N = 6); and group 3: DVC of bleeding site without aortic clamping (N = 6). After hemorrhage, EDT or SCC was performed in groups 1 and 2, respectively, with subsequent exploration of the bleeding site and placement of a temporary vascular shunt (TVS). Group 3 (DVC) underwent direct exploration of the injury and placement of a TVS. All groups were resuscitated to predefined physiologic endpoints over 6 hours with repeated measures of central and cerebral perfusion and end-organ function at standardized time points. Postmortem tissue analysis was performed to quantify injury to critical tissue beds. There was no difference in mortality among the groups and no TVS failures. Central aortic pressure, carotid flow, and partial pressure brain tissue oximetry, all demonstrated increases in EDT and SCC after application of the aortic clamp relative to DVC (p < 0.05). During resuscitation, serum lactate levels were higher in EDT compared with SCC and DVC (6.85 vs. 3.08 and 2.15, respectively; p < 0.05) and serum pH in EDT reflected greater acidosis than SCC and DVC (7.24 vs. 7.36 and 7.39, respectively; p < 0.05). EDT and SCC required more intravenous fluid than DVC (2,166 mL and 2,166 mL vs. 667 mL, respectively; p < 0.05) and more vasopressors were used in EDT and SCC compared with DVC (52.1 μg and 43.5 μg vs. 12.4 μg, respectively; p < 0.05). Brain and myocardial tissue stains demonstrated the same degree of acute ischemic changes in all groups. Although aortic clamping increases central and cerebral perfusion, DVC results in less physiologic derangement. The optimal method of aortic control would incorporate the benefits of maintained central pressure with less associated morbidity. Clinical studies evaluating DVC are warranted.

E-003 Localization of spinal dural arteriovenous fistula: diagnosis and implications

PurposeSpinal Dural Arteriovenous Fistula (SDAVF) is a rare acquired lesion that can impair spinal cord function. Early diagnosis is very important since the symptoms can be reversed if treated prior...

Subclavian Pseudoaneurysm Repair After Blalock-Taussig Shunt Placement

A 7-day-old male with tricuspid atresia, pulmonary atresia, and D-transposition of the great vessels underwent surgical placement of a modified Blalock-Taussig (mBT) shunt and was found to have a pseudoaneurysm on the follow-up echocardiogram. Surgical exploration identified a pseudoaneurysm arising from the right subclavian artery and not from the innominate artery at the site of the mBT shunt. It was concluded that this was caused by an inadvertent needlestick during central line placement. The fistula tract between the right subclavian artery and the false aneurysm was oversewn, and the postoperative course was unremarkable.

How the python heart separates pulmonary and systemic blood pressures and blood flows

The multiple convergent evolution of high systemic blood pressure among terrestrial vertebrates has always been accompanied by lowered pulmonary pressure. In mammals, birds and crocodilians, this cardiac separation of pressures relies on the complete division of the right and left ventricles by a complete ventricular septum. However, the anatomy of the ventricle of most reptiles does not allow for complete anatomical division, but the hearts of pythons and varanid lizards can produce high systemic blood pressure while keeping the pulmonary blood pressure low. It is also known that these two groups of reptiles are characterised by low magnitudes of cardiac shunts. Little, however, is known about the mechanisms that allow for this pressure separation. Here we provide a description of cardiac structures and intracardiac events that have been revealed by ultrasonic measurements and angioscopy. Echocardiography revealed that the atrioventricular valves descend deep into the ventricle during ventricular filling and thereby greatly reduce the communication between the systemic (cavum arteriosum) and pulmonary (cavum pulmonale) ventricular chambers during diastole. Angioscopy and echocardiography showed how the two incomplete septa, the muscular ridge and the bulbuslamelle - ventricular structures common to all squamates - contract against each other in systole and provide functional division of the anatomically subdivided ventricle. Washout shunts are inevitable in the subdivided snake ventricle, but we show that the site of shunting, the cavum venosum, is very small throughout the cardiac cycle. It is concluded that the python ventricle is incapable of the pronounced and variable shunts of other snakes, because of its architecture and valvular mechanics.

Occipital Intradiploic CSF Pseudocyst: An Unusual Complication of a Ventriculoperitoneal Shunt Malfunction

We report a rare and unique complication of ventriculoperitoneal (VP) shunt malfunction. A progressively expansile, CSF-containing occipital intradiploic cyst developed in a 15-year-old boy at the site of cystoperitoneal shunt draining a Dandy-Walker cyst; the shunt was placed when the boy was 4 years old. A proposed pathogenesis of the lesion is discussed.

Morphological Studies of Pulmonary Arteriovenous Shunting in a Lamb Model of Superior Cavopulmonary Anastomosis

We sought to identify and characterize the abnormal vascular structures responsible for pulmonary arteriovenous shunting following the Glenn cavopulmonary shunt. Superior cavopulmonary shunt is commonly performed as part of the staged pathway to total cavopulmonary shunt to treat univentricular forms of congenital heart disease, however, clinically significant pulmonary arteriovenous malformations develop in some patients after the procedure. The causes of pulmonary arteriovenous malformations and other pulmonary vascular changes that occur after cavopulmonary shunt are not known. Using a juvenile lamb model of superior cavopulmonary anastomosis that reliably produces pulmonary arteriovenous malformations, we performed echocardiography and morphological analyses to determine the anatomic site of shunting and to identify the vascular structures involved. Pulmonary arteriovenous shunting was identified by contrast echocardiography in all surviving animals (n = 40) following superior cavopulmonary anastomosis. Pulmonary vascular corrosion casts revealed abnormal tortuous vessels joining pulmonary arteries and veins in cavopulmonary shunt animals but not control animals. In conclusion, unusual channels that bridged pulmonary arteries and veins were identified. These may represent the vascular structures responsible for arteriovenous shunting following the classic Glenn cavopulmonary shunt. Detailed analysis of these structures may elucidate factors responsible for their development.