Drag Forces after Thoracic Endovascular Aortic Repair. General Review of the Literature.

BACKGROUND: Despite the great evolution of endograft devices for thoracic endovascular aortic repair (TEVAR), threatening related complication such as graft migration and endoleaks still occur during follow up. The Drag Forces (DF), that is the displacement forces that play a role in graft migration and endoleaks caused by the blood flow against the thoracic graft, can be studied by means of Computational Fluid Dynamics (CFD). METHOD: A general review of papers found in current literature was performed. CFD studies available on the topic of thoracic aortic diseases and DF were analyzed. All anatomic, hemodynamics or graft related factors which could have an impact on DF were reported. RESULTS: Different factors deeply influence DF magnitude in the different site of the Ishimaru's zones classification: angulation, tortuosity and length of the landing zone, graft diameter, length and deployment position, blood pressure, pulse waveform, blood viscosity and patient heart rate have been related to the magnitude of DF. Moreover, also the three-dimensional orientation of DF is emerging as a fundamental issue from CFD studies. DF can be divided in sideways and upward components. The former, even of higher magnitude in zone 0, maintain always an orthogonal orientation and does not change in any type of aortic arch; the latter result strictly related to the anatomic complexity of the aortic arch with values up to four times higher in zone 3. CONCLUSION: Different DF magnitude and orientation could explain how TEVAR have higher rate of migration and endoleaks when we face with more complex aortic anatomies. All these aspects should be foreseen during the planning of TEVAR procedure. In this field, collaboration between physicians and engineers is crucial, as both parts have a primary role in understanding and describing hidden aspects involved in TEVAR procedures.

Another Use for EUS: Removal of a Transesophageal-Migrated Mediastinal Foreign Body.

Removal of foreign bodies from the upper gastrointestinal tract, though a common occurrence, can be technically challenging and risky. We report the case of a young man that, after eating a pizza cooked in a wood-burning oven, reported a sense of foreign body. Though the first evaluation by fiberoptic laryngoscopy found no foreign body, after a few weeks, the patient was readmitted from the ER for worsening symptoms and fever. A CT scan showed a metallic mediastinal foreign body inside a large fluid collection. After multidisciplinary evaluation, an endoscopic removal was attempted by accessing the mediastinal collection through EUS-guided positioning of a Hot Axios™ stent. The cavity was drained by naso-esophageal suction. The foreign body was a fragment of the brush used to clean the oven. The patient is now doing well after 7 months.

Successful repositioning of apically tethered transcatheter mitral valve replacement in the off-bypass, beating heart.

A 73-year-old man with severe, symptomatic secondary mitral regurgitation (MR) underwent successful transcatheter mitral valve replacement using the Tendyne™ mitral valve system. The device was deployed from the left ventricular (LV) apex and secured in position by a tether attached to an epicardial pad. Three days postoperatively, the patient developed hemolytic anemia and a paravalvular leak (PVL) associated with indentation of the LV apex. Adjustment of the tether tension and placement of an epicardial disc under the pad resulted in reduction in the PVL, and resolution of the hemolytic anemia.

Migration of hem-o-lock clips and stitches into the duodenum after laparoscopic hepatectomy and cholecystectomy: A case report.

RATIONALE: Migration of endoclips and stitches into the duodenum after laparoscopic hepatectomy is incredibly rare with a poorly understood mechanism. PATIENT CONCERNS: A 56-year-old woman who underwent laparoscopic left hepatectomy and cholecystectomy in August 2016 was admitted to our hospital with nausea and vomiting in December 2017. DIAGNOSES: Abdominal computed tomography (CT) scan showed high density shades in duodenal ampulla. Esophagogastroduodenoscopy showed deformation of the duodenal ampulla into two lumens; hem-o-lock clips and stitches were detected in the upper lumen. Contrast enhanced CT scan revealed gastric cancer with liver metastasis (GCLM). INTERVENTIONS: The hem-o-lock clips and stitches were present in the wall of the duodenum; therefore, no attempt was made to remove them. High quality liquid diet, partial parenteral nutrition, and chemotherapy were administered to the patient. OUTCOMES: In September 2018, the patient died of hepatic failure caused by GCLM. LESSONS: This rare complication of the migration of endoclips and stitches into the duodenum after laparoscopic hepatectomy can cause epigastric pain and duodenal obstruction. The complication could be potentially avoided using absorbable endoclips and stitches or by performing of ultrasonic dissection by a skilled operator.

Odyssey of an accidently ingested sewing needle from mouth to mesentery of small bowel in a young female - Case Report.

Foreign body (FB) ingestion is one of the most common complaint in the emergency room and, extra-intestinal migration of penetrating sharp FBs is one of the most overlooked aspect of medical research. We report a case of accidental ingestion of a sewing needle which was recovered from the mesentery. The 28-year-old female presented to our hospital with abdominal pain and one-month's history of needle ingestion. Initially laparoscopy was performed, which was inconclusive. Afterward, through laparotomy, the needle was successfully removed from the mesentery of small bowel.

Exploring pyloric dynamics in stenting using a distensibility technique.

BACKGROUND: Perforated duodenal ulcers can be treated with a covered stent. Stent migration is a severe complication, sometimes requiring surgery. Pyloric physiology during stent treatment has not been studied and mechanisms for migration are unknown. The aim of this study was to investigate the pyloric response to distention, mimicking stent treatment, using the EndoFLIP. METHODS: A nonsurvival study in five pigs was carried out, followed by a pilot study in one volunteer. Animals were gastroscoped during anaesthesia and the EndoFLIP was placed straddling the pylorus. Baseline distensibility readings were performed at stepwise balloon distentions to 20, 30, 40, and 50 mL, measuring pyloric cross-sectional area and pressure. Measurements were repeated after administration of a prokinetic drug and after a liquid meal. In the human study, readings were performed in conscious sedation at baseline and after stimulation with metoclopramide. KEY RESULTS: During baseline readings, the pylorus was shown to open more with increasing distention together with higher amplitude motility waves. Reaching maximum distention-volume (50 mL), pyloric pressure increased significantly (P = 0.016), and motility waves disappeared. After prokinetic stimulation, the pressure decreased and the motility waves increased in frequency and amplitude. After food stimulation, the pressure stayed low and the motility showed increase in amplitude. During both tests, the pylorus showed higher pressure and lack of motility waves at maximum probe distention. CONCLUSIONS AND INFERENCES: The pylorus seems to act as a sphincter at low distention but when further dilated starts acting as a pump. Fully distended the pyloric motility disappears and the pressure remains high, suggesting that a stent with high-radial force might show less migration.

Calculation of iris-claw IOL power for correction of late in-the-bag IOL complex dislocation.

BACKGROUND: To assess the constants and formula for aphakia correction with iris-claw IOLs to achieve the best refractive status in cases of late in-the-bag IOL complex dislocation. METHODS: A literature search was performed. The following data were obtained: Iris-claw IOL model, Iridal or retroiridal enclavation, A-constant, ultrasound or optical biometry, formula employed and refractive outcomes. Acceptable emmetropia was considered if the resulting spherical equivalent (SE) was within ±1.00 D. RESULTS: The majority of the studies used SRK/T formula (66.6%). The 88.9% of the reports obtained a SE within ±1.00 D. Using A-115 for ultrasound biometry and A-115.7 for optical biometry and SRK/T formula, the emmetropia (±1.00 D) of SE, was able to get near 100% of reported cases over the pupil implantation. However, the emmetropia decreased to 80% when the enclavation is retropupilar using the same formula. The A-constant can vary from 116.7 to 117.5 for retropupilar enclavation. CONCLUSIONS: Using A-115 for ultrasound biometry and A-115.7 for optical biometry and SRK/T formula, ±1.00 D of SE, is able to get near 100% of cases. Nevertheless, ±1.00 D of SE decreased to 80% of the cases when the enclavation is retropupilar.

Fractured Superior Mesenteric Artery Stent With Stent Displacement Leading to Recurrent Symptoms of Superior Mesenteric Ischemia.

We report a case of a patient with recurrent symptoms of superior mesenteric ischemia 7 months after successful percutaneous angioplasty and implantation of a stent in the superior mesenteric artery (SMA). Stent fracture and stent displacement were observed. To the best of our knowledge, this is the first report of SMA stent fracture with stent displacement.

Changes in electromyographic amplitudes but not latencies occur with endotracheal tube malpositioning during intraoperative monitoring for thyroid surgery: Implications for guidelines.

OBJECTIVES/HYPOTHESIS: During intraoperative neural monitoring (IONM) in thyroid and parathyroid surgery, endotracheal (ET) tube migration can result in a decrease in vocalis electromyographic (EMG) amplitude without a concordant latency elevation during stimulation of the recurrent laryngeal nerve (RLN). STUDY DESIGN: Retrospective review. METHODS: Data were reviewed retrospectively for thyroid and parathyroid surgery patients with IONM of the laryngeal nerves from January 2015 to December 2015. Recordings of vocalis EMG amplitudes and latencies with RLN stimulation were obtained with the neuromonitoring ET tube surface electrodes in optimal baseline position, with vertical displacement away from the vocalis, and with rotational change away from baseline. RESULTS: ET tube surface electrode EMG recordings were obtained with stimulation of seven left and three right RLNs in a total of 10 patients. Mean vocalis EMG amplitudes were reduced with vertical displacement 1 and 2 cm both inferior and superior to baseline and with rotational change (45° and 90° clockwise and counterclockwise, 180°), although amplitude change with 45° clockwise and 180° rotation did not meet statistical significance. Mean EMG latency values did not change significantly from baseline with either rotation or vertical displacement of the ET tube. CONCLUSIONS: An isolated decrease in EMG amplitude without concordant latency elevation should warrant re-evaluation of ET tube position during thyroid and parathyroid surgery and is in contrast to a combined event, with both EMG amplitude decrease and concordant latency increase, which is more suggestive of a true neuropraxic injury. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:2182-2188, 2017.

Late Retrograde Migration of a Left Subclavian Artery Chimney Stent-Graft Into the Innominate Artery.

PURPOSE: To report an uncommon case of chimney stent-graft migration in the aortic arch. CASE REPORT: A 29-year-old man presented with chronic left arm hyposthenia after late displacement and thrombosis of a left subclavian artery (LSA) chimney graft that migrated retrogradely into the innominate artery 2 years after deployment. The self-expanding LSA chimney was placed during a redo procedure to repair a pseudoaneurysm and type I endoleak after an index emergency thoracic endovascular aortic repair for traumatic aortic rupture 1 year earlier. The patient was successfully treated in an elective procedure via a median sternotomy, with arch aortotomy under circulatory arrest to remove the proximal end of the thrombosed chimney graft from the ostium of the innominate trunk. Three months later, a left carotid-to-subclavian bypass was performed to restore flow to the left arm. CONCLUSION: Migration of the proximal end of an overly long chimney graft that moved freely in the aortic arch exposed the patient to a high risk of stroke and death. Because of the high-risk situation, open repair under circulatory arrest was elected to remove the proximal end of the chimney graft, with no major complications.

Type IIIb Endoleak and Relining: A Mathematical Model of Distraction Forces.

PURPOSE: To examine the changes in distraction force following relining of a conventional abdominal aortic stent-graft with a type IIIb endoleak using the Nellix endovascular sealing device compared to a unilateral stent-graft. METHODS: Relining is often used to repair type IIIb endoleaks, but the consequences to graft stability are unknown. A mathematical model was constructed based on pressure and volume flow through the stent-grafts, incorporating recognized distraction force equations. Steady flow was presumed at peak systolic pressures to calculate the maximum distraction force, with gravity ignored. Distraction forces for 28- to 36-mm-diameter stent-graft bodies with 16-mm limbs were calculated and compared to forces following relining with single and double Nellix devices or the Renu unilateral device. RESULTS: Distraction forces for the 28-, 32-, and 36-mm stent-grafts prior to relining were 5.99, 10.21, and 14.99 N, respectively. Similar forces were reported after relining with bilateral Nellix devices (5.86, 10.08, and 14.86 N, respectively). However, use of a unilateral Nellix increased the distraction forces to 9.92, 14.14, and 18.92 N, respectively. These were comparable to the increase observed after relining with a Renu unilateral stent-graft (9.87, 14.09, and 18.86 N, respectively). The proportional increase in distraction force for a unilateral relining ranged from 26% to 66%, with the greatest increase noted in the smaller diameter main bodies. CONCLUSION: Relining a stent-graft with a type IIIb endoleak using bilateral Nellix devices does not increase the distraction force. However, a unilateral Nellix device or the Renu system could theoretically increase the distraction force by up to 66%, potentially risking migration and type Ia endoleak. In clinical practice, these results suggest that a relining with bilateral Nellix may have benefits over the Renu unilateral stent-graft.

Proximal thoracic endograft displacement rescued by balloon-assisted pull-back, external shunting, and in situ fenestration of the left carotid artery.

Proximal displacement of thoracic aortic endografts is a catastrophic adverse event, which rarely occurs but is associated with extremely high morbidity and mortality. We describe herein the case of a patient with accidental proximal displacement of a thoracic endograft with occlusion of all supra-aortic branches, successfully rescued by the combination of three advanced endovascular techniques: (1) aggressive pull-back maneuver with a compliant balloon; (2) establishment of an arterio-arterial temporary shunt to the occluded carotid artery over sheaths; and (3) in-situ fenestration of the occluded carotid artery.

Use of parallel grafts to save failed prior endovascular aortic aneurysm repair and type Ia endoleaks.

OBJECTIVE: The aim of this study was the evaluation of the clinical and radiologic outcomes of parallel grafts in the treatment of patients with failed prior endovascular aneurysm repair and type Ia endoleak. METHODS: Prospectively collected clinical and radiologic data of consecutive patients with prior endovascular aneurysm repair and evidence of type Ia endoleak were analyzed. All patients were treated between January 2009 and November 2014 by use of parallel grafts, ie, chimney/snorkel or periscope grafts and abdominal endovascular devices. Primary outcome of the study was the technical success. Secondary outcomes were patency of the chimney grafts and shrinkage of aneurysm morphology. RESULTS: Technical success was 94.4% (17 of 18). One patient showed evidence of persistent type Ia endoleak after triple chimney graft placement and treated by Onyx embolization (Covidien, Plymouth, Minn) successfully. The mean preoperative and postoperative aneurysm diameters were 7.1 ± 1.7 and 7.0 ± 2 cm. Primary patency of the chimney grafts was 96.7% and assisted patency was 100% after successful retrograde recanalization of an acute occlusion of the superior mesenteric artery from the celiac trunk and the gastroduodenal artery. One patient who had undergone the sandwich technique with transfemoral placement of the flexible Viabahn (W. L. Gore & Associates, Flagstaff, Ariz) due to impossible catheterization of the target vessel from the upper extremity presented with contained rupture caused by gutter-associated endoleak and underwent urgent embolization with Onyx successfully. No procedure-related death or open conversion was observed in the entire follow-up period. CONCLUSIONS: Use of parallel grafts showed midterm safety and feasibility with low incidence of persistent endoleaks requiring intervention or progression of aneurysm diameter. Reproducible results from other vascular centers will establish the chimney technique in the treatment of type I endoleaks as a viable endovascular modality.

Computational fluid dynamic analysis of the effect of morphologic features on distraction forces in fenestrated stent grafts.

OBJECTIVE: Secure fixation of endovascular stent grafts is essential for successful endovascular aneurysm repair. Hemodynamic distraction forces are generated by blood pressure and blood flow and act against fixation force to encourage migration that may eventually lead to late stent graft failure. The aim of this in silico study was to determine which morphologic features were associated with greater distraction force. METHODS: Computer models of 54 in situ fenestrated stent grafts were constructed from postoperative computed tomography scans by use of image processing software. Computational fluid dynamic analysis was then performed by use of a commercial finite volume solver with boundary conditions representative of peak systole. Distraction force results were obtained for each component of the stent graft. Distraction force was correlated with lumen cross-sectional area (XSA) at the inlet and outlet of components and was compared between groups of components, depending on the magnitude of four predefined angles within the aortoiliac territory that we describe in detail. RESULTS: Median total resultant distraction force (RDF) acting on the fenestrated proximal bodies was 4.8 N (1.3-15.7 N); bifurcated distal bodies, 5.6N (1.0-8.0 N); and limb extensions, 1.7 N (0.6-8.4N). Inlet XSA exhibited strong, positive correlation with total RDF in proximal body and distal body components (Spearman correlation coefficient ρ, 0.883 and 0.802, respectively). Outlet XSA exhibited a similarly strong, positive correlation with total RDF in limb extension components (ρ, 0.822). Outlet angulation ≥ 45 degrees was associated with greater total RDF in the limb extension components only (P = .004). CONCLUSIONS: For a given blood pressure, XSA was the most important morphologic determinant of total RDF. Angulation within the aorta was not large enough to influence this, whereas iliac angulation affecting outlet angulation of limb extension components was associated with significantly greater total RDF.

Bioevaluation of (125) I Ocu-Prosta seeds for application in prostate cancer brachytherapy.

BACKGROUND & OBJECTIVES: In recent years, brachytherapy involving permanent radioactive seed implantation has emerged as an effective modality for the management of cancer of prostate. 125 I-Ocu-Prosta seeds were indigenously developed and studies were carried out to assess the safety of the indigenously developed 125 I-Ocu-Prosta seeds for treatment of prostate cancer. METHODS: Animal experiments were performed to assess the likelihood of in vivo release of 125 I from radioactive seeds and migration of seeds implanted in the prostate gland of the rabbit. In vivo release of 125 I activity was monitored by serial blood sampling from the auricular vein and subsequent measurement of 125 I activity. Serial computed tomography (CT) scans were done at regular intervals till 6 months post implant to assess the physical migration of the seeds. RESULTS: The laser welded seeds maintained their hermeticity and prevented the in vivo release of 125 I activity into the blood as no radioactivity was detected during follow up blood measurements. Our study showed that the miniature 125 I seeds were clearly resolved in CT images. Seeds remained within the prostate gland during the entire study period. Moreover, the seed displacement was minimal even within the prostate gland. INTERPRETATION & CONCLUSIONS: Our findings have demonstrated that indigenously developed 125 I-Ocu-Prosta seeds may be suitable for application in treatment of prostate cancer.

Displacement forces in iliac landing zones and stent graft interconnections in endovascular aortic repair: an experimental study.

OBJECTIVES: Stent graft migration influences the long-term durability of endovascular aortic repair. Flow-induced displacement forces acting on the attachment zones may contribute to migration. Proximal fixation of aortic stent grafts has been improved by using hooks, while distal fixation and stent graft interconnections depend on self-expansion forces only. We hypothesized that flow-induced displacement forces would be significant at the distal end, and would correlate with graft movements. METHODS: As part of an experimental study, an iliac limb stent graft was inserted in a pulsatile flow model similar to aortic in vivo conditions, and fixed-mounted at its proximal and distal ends to strain gauge load cells. Peak displacement forces at both ends and pulsatile graft movement were recorded at different graft angulations (0-90°), perfusion pressures (145/80, 170/90, or 195/100 mmHg), and stroke frequencies (60-100 b.p.m.). RESULTS: Flow-induced forces were of the same magnitude at the proximal and distal end of the stent graft (peak 1.8 N). Both the forces and graft movement increased with angulation and perfusion pressure, but not with stroke rate. Graft movement reached a maximum of 0.29 ± 0.01 mm per stroke despite fixed ends. There were strong correlations between proximal and distal displacement forces (r = 0.97, p < .001), and between displacement forces and graft movement (r = 0.98, p < .001). CONCLUSIONS: Pulsatile flow through a tubular untapered stent graft causes forces of similar magnitude at both ends and induces pulsatile graft movements in its unsupported mid-section. Peak forces are close to those previously reported to be required to extract a stent graft. The forces and movements increase with increasing graft angulation and perfusion pressure. Improved anchoring of the distal end of stent grafts may be considered.