Hepatic Hilar Nerve Block for Hepatic Interventions: Anatomy, Technique, and Initial Clinical Experience in Thermal Ablation of Liver Tumors.

Background Image-guided procedures for treatment of liver diseases can be painful and require heavy sedation of the patient. Local-regional nerve blocks improve pain control and reduce oversedation risks, but there are no documented liver-specific nerve blocks. Purpose To develop a safe and technically simple liver-specific nerve block. Materials and Methods Between March 2017 and October 2019, three cadavers were dissected to evaluate the hepatic hilar anatomy. The hepatic hilar nerves were targeted with transhepatic placement of a needle adjacent to the main portal vein, under US guidance, and evaluated with use of an injection of methylene blue. A hepatic nerve block, using similar technique and 0.25% bupivacaine, was offered to patients undergoing liver tumoral ablation. In a prospective pilot study, 12 patients who received the nerve block were compared with a control group regarding complications, safety, pain scores, and intraoperative opioid requirement. Student t tests were used to compare the groups' characteristics, and Mann-Whitney U tests were used for the measured outcomes. Results Cadaver results confirmed that the hepatic nerves coursing in the hepatic hilum can be targeted with US for injection of anesthetic agents, with adequate spread of injected methylene blue around the nerves in the hepatic hilar perivascular space. The 12 participants (mean age ± standard deviation, 66 years ± 13; eight men) who received a hepatic hilar block before liver thermal ablations demonstrated reduced pain compared with a control group of 12 participants (mean age, 63 years ± 15; eight men) who received only intravenous sedation. Participants who received the nerve block had a lower mean visual analog scale score for pain than the control group (3.9 ± 2.4 vs 7.0 ± 2.8, respectively; P = .01) and decreased need for intraprocedural fentanyl (mean dose, 152 µg ± 78.0 vs 235.4 µg ± 58.2, respectively; P = .01). No major complications occurred in the hepatic hilar nerve block group. Conclusion A dedicated hepatic hilar nerve block with 0.25% bupivacaine can be safely performed to provide anesthesia during liver tumoral ablation. © RSNA, 2021.

An update on vessel preparation in lower limb arterial intervention.

BACKGROUND: Plain balloon angioplasty has traditionally been used to treat lower limb arterial disease but can be limited by significant residual stenosis, vessel recoil, dissection, and by late restenosis. Appropriate vessel preparation may significantly improve short and long-term outcomes. We aim to give an overview of some of the devices currently available, or under investigation, for vessel preparation in the lower limb. MAIN TEXT: Vessel preparation devices include those that remove plaque (atherectomy devices) and those that modify plaque. The four groups of plaque removing atherectomy devices are defined by their plaque removal method: Directional, rotational orbital and excimer laser are categories of devices investigated for plaque modification. Intravascular lithotripsy devices generate sonic pulsatile pressure waves that pass into the vessel wall cracking calcified plaques whilst sparing soft tissue. This enables dilatation of calcified lesions at low pressure by conventional balloons and enables full stent expansion. Other balloon based vessel preparation devices were designed to modify plaque and produce more controlled, lower pressure luminal expansion without major dissections and potentially with less recoil than conventional angioplasty balloons. Scoring balloons have a helical nitinol element attached to the balloon that scores plaque facilitating uniform luminal enlargement. Further specialty balloons have been developed in recent years, including the Chocolate, Phoenix and Serranator balloons. Finally, the temporary Spur self-expanding retrievable nitinol stent has a series of radially aligned spurs that are driven into the vessel wall by post-dilatation, potentially improving drug delivery. CONCLUSION: Lesion specific vessel preparation aims to improve both short and long term outcomes through improved penetration of anti-proliferative drug, maximising luminal gain, reducing the need for stent placement and minimising intimal injury. Some forms of vessel preparation appear to improve short term outcomes; long-term outcomes remain uncertain. An overview of some of the multiple devices available for vessel preparation is presented.

Delayed migration of a peripherally inserted central venous catheter to the azygos vein with subsequent perforation.

Peripherally inserted central venous catheters (PICCs) are often used for infusion of chemotherapeutic agents, long-term antibiotics or total parenteral nutrition (TPN). We present a case of delayed migration of a PICC inserted for TPN from the superior vena cava into the azygos vein that was not initially recognized on chest radiographs or CT scan. This subsequently led to azygos perforation and extravasation of the TPN solution into the mediastinal, pleural and pericardial spaces. Several anatomical and procedural factors predispose to PICC migration. In this patient, the risk of PICC migration was increased by left-sided insertion and variant azygos anatomy. If a curve in the distal tip of a PICC is seen on a frontal chest radiograph, azygos malposition should be suspected and confirmed with a lateral radiograph, CT scan or catheter injection. This is because azygos malposition increases the risk of venous perforation and needs to be corrected.

A Model Example: Coexisting Superior Mesenteric Artery Syndrome and the Nutcracker Phenomenon.

Superior mesenteric artery (SMA) syndrome is a rare cause of gastrointestinal obstruction, caused by external compression of the third part of the duodenum by the SMA. It may be associated with the Nutcracker phenomenon: external compression of the left renal vein. To our knowledge, there are few reports in the literature describing the coexistence of these two conditions and so we take this opportunity to highlight a rare cause of the acute abdomen that might otherwise be overlooked in cases of nonspecific abdominal findings and potentially unremarkable initial investigations. We report a case of SMA syndrome and Nutcracker phenomenon in a 19-year-old female who presented to our emergency department with a short history of epigastric pain and emesis. The SMA syndrome is thought to develop as the result of an abnormally narrow angle between the proximal SMA and the aorta, for which a number of predisposing factors have been described. Surgical options exist; however, the SMA syndrome is typically managed conservatively in the first instance, consistent with the approach described in this case. The Nutcracker phenomenon may give rise to the Nutcracker syndrome in the presence of typical clinical manifestations; however, these did not feature in this case.