Segmental Arterial Mediolysis Research Articles

Segmental arterial mediolysis: vasculopathy presenting as acute abdominal pain

Segmental arterial mediolysis, initially termed segmental mediolytic arteritis, is a rare noninflammatory, non-atherosclerotic vasculopathy that primarily affects visceral arteries. SAM presents with a unique skip pattern of arterial involvement and is characterized by the degeneration of the arterial medial layer, leading to various vascular abnormalities. We present the case of a fit and healthy 50-year-old Male who sought medical attention for the sudden onset of severe abdominal pain. This led to the diagnosis of SAM after repeated imaging and blood investigations. The considered differential diagnoses include fibromuscular dysplasia, vasculitis, and mycotic aneurysms. This case underscores the importance of clinical awareness and multidisciplinary collaboration in diagnosis and managing SAM, offering valuable insights into its clinical presentation and the complexities surrounding its diagnosis and treatment. Conclusively, SAM is treated conservatively by emphasizing blood pressure control, antiplatelet therapy, and anticoagulation. However, endovascular intervention is deemed necessary if there is evidence of end-organ ischemia.

Gallbladder hemorrhage associated with segmental arterial mediolysis: a case report

BackgroundGallbladder hemorrhage is a rare but fatal condition. The reported causes of gallbladder hemorrhage include iatrogenesis, atherosclerotic changes in the cystic arteries, acute cholecystitis or cholelithiasis, malignancy, trauma, hemophilia, pseudoaneurysm, and the use of oral anticoagulant medications. Recently, segmental arterial mediolysis (SAM) has been reported as a possible etiology of life-threatening abdominal, retroperitoneal, and intracranial hemorrhages. However, no previous reports have described the association between gallbladder hemorrhage and SAM.Case presentationA 59-year-old man was transferred to our hospital complaining of upper abdominal pain and vomiting. Contrast-enhanced computed tomography revealed high-density images of the gallbladder and common bile duct. However, there were no obvious findings of gallstones, cholecystitis, tumors, or aneurysms. He was diagnosed with gallbladder hemorrhage and bile duct obstruction. We performed a laparoscopic cholecystectomy after endoscopic biliary drainage. The gross appearance of the surgically resected specimen showed 12 small (3–12 mm), slightly elevated lesions on the gallbladder mucosa. Histologically, these slightly elevated lesions consisted of dilated muscular arteries of the gallbladder wall with fibrinoid degeneration of the media and focal loss of the internal and external elastic laminae. The histopathological diagnosis was confirmed as SAM.ConclusionsTo the best of our knowledge, this is the first reported case of a gallbladder hemorrhage associated with SAM. Our case report shows that SAM can cause gallbladder hemorrhage, suggesting that SAM should be considered in the differential diagnosis of gallbladder hemorrhage.

Segmental Arterial Mediolysis and its Mimickers: A Case Report and Review of the Literature.

Segmental arterial mediolysis (SAM) is a rare and underdiagnosed vasculopathy.SAM is a challenging diagnosis and should not be confused with vasculitis.SAM has a good prognosis with spontaneous resolution in most cases.

血胸を伴う出血性ショックを来した左胃動脈瘤破裂の1例(A ruptured aneurysm of left gastric artery that progressed to right hemothorax: a case report)

症例は50歳代女性，心窩部痛と呼吸苦で発症し，近医にて胸水を指摘されて前医を受診した。前医では，単純CT検査で血性胸腹水，食道壁肥厚，膵周囲の脂肪織濃度の上昇を認め，2日間加療したが改善を認めないため精査目的に当院へ紹介された。来院時，四肢末梢に湿潤を認め，脈拍110/分，血圧80/50mmHg（ドパミン9μg/kg/min）であった。造影CT検査で右血性胸水と食道裂孔ヘルニア，胸部中部以下の食道から胃噴門部小弯側にかけての血腫を認めたが，食道や肺野など胸部には出血源を認めなかった。腹腔内には血性腹水とともに，胸部中部食道周囲から胃小彎側に連続する血腫を認め，内部に直径1.5cmの左胃動脈瘤を認めた。左胃動脈瘤破裂による出血が，食道裂孔を介して縦隔へ進展し，胸腔内に穿破して血胸に至ったものと推測した。血胸に対して単回の胸腔穿刺，左胃動脈瘤破裂に対して血管造影による塞栓術を施行した。翌日から経口摂取を開始し，血胸が再燃することもなく経過は良好で，第22病日に自宅退院した。腹部内臓動脈瘤破裂による出血が食道裂孔を介して胸腔内に穿破し，血胸を契機に診断された稀な症例を経験したので報告する。 A 59–year–old woman visited her local hospital with dyspnea and epigastric pain. A chest X–ray showed a right pleural effusion. The patient consulted a second hospital where she was treated for two days, but due to her unstable vital signs, she was transferred to our hospital. A contrast–enhanced CT scan revealed a right hemothorax and esophageal hiatal hernia. While there was no source of bleeding in the thoracic cavity, there was an intra–abdominal hemorrhage from a ruptured aneurysm of the left gastric artery. The suspected cause of the hemothorax was bleeding from a ruptured aneurysm that entered the thoracic cavity through the esophageal hiatus. We performed a transcatheter arterial embolization for the ruptured aneurysm. After treatment, the patient recovered without significant incidents and was discharged on the 22nd day of hospitalization. We speculated that the hemorrhage from the rupture of the gastric aneurysm extended through the esophageal hiatus into the mediastinum and perforated into the thoracic cavity, resulting in a hemothorax. Since such conditions are rare, we will report this case with a review of the literature. 腹部内臓動脈瘤は破裂すれば出血性ショックにより致死的状況に至ることもある重篤な疾患である。本邦の腹部内臓動脈瘤破裂として報告されている症例の多くは腹腔内出血による出血性ショックを呈している 1, 2。しかし，今回我々は左胃動脈瘤破裂による出血が食道裂孔ヘルニアを介して縦隔，胸腔内へ進展し，出血性ショックを来した症例を経験したので，文献的考察を加えて報告する。 本論文は，個人情報保護法に基づいて匿名化がなされており，本人から論文報告に関する同意を得ている。また，本論文は倫理委員会の承諾を要する事項として該当しない。 症 例：50歳代の女性 主 訴：心窩部痛 現病歴：搬送6日前に突然の心窩部痛，呼吸困難感が出現し，食事摂取ができなくなった。搬送2日前に近医を受診したところ，胸水を指摘され前医を紹介された。前医受診時より血圧が低下しており，単純CT検査で血性胸腹水，食道壁肥厚，膵周囲の脂肪織濃度の上昇を認め急性膵炎などが疑われた。2日間の入院加療後も改善に乏しく，循環動態の維持にカテコラミン投与を要する状態となったため，当院救命救急センターへ搬送された。 既往歴：特記事項なし 生活歴：ビール１本/日，喫煙なし 来院時現症：意識清明。軽度の呼吸困難感の訴えを認めるが呼吸促拍はなく，呼吸数22/分，酸素飽和度97%（3L/min），顔面蒼白，四肢末梢に冷感湿潤を認め，脈拍110/分，血圧80/50mmHg（ドパミン 9µg/kg/min）。左背部痛の訴えがあるものの圧痛は認めなかった。 血液検査：RBC 213×104 /μL，Hb 6.7g/dL（前医受診時 Hb 9.8g/dL）と著明な貧血を認めた。血小板数や凝固検査には異常を認めなかった。 画像検査：胸腹部造影CT検査；胸部CTでは右血胸，滑脱型食道裂孔ヘルニアを認め，周囲に縦隔血腫，左少量胸水を認めた。腹部CTでは直径1.5cmの左胃動脈瘤を認め（Fig. 1a），周囲の血腫は胸部中部食道周囲から胃小弯側へ連続していた（Fig. 1b）。左肝動脈は左胃動脈から分岐しており，肝左葉外側区に微小動脈瘤を認めた。食道や肺野には出血源を認めなかった。 An enhanced CT scan of the abdomen revealed a pseudoaneurysm of the left gastric artery. Computed tomography (CT) of the chest showed a right massive hemothorax，a slipped esophageal hiatal hernia, and a mediastinal fluid collection (black arrow). 搬入後経過：乳酸リンゲル液の急速輸液を行うとともに輸血を開始した。搬入後より呼吸困難感が増悪し，仰臥位の維持が困難となったため，右血胸に対し慎重に胸腔穿刺を施行したところ，約830mLの血性排液を認めた。穿刺後，呼吸困難感の改善を認め，輸血投与後よりバイタルサインの安定を得た。左胃動脈瘤からの出血が食道裂孔ヘルニアを介して血胸に進展したものと推測し，動脈瘤に対して緊急interventional radiology（IVR）による止血術を行う方針とした。 腹部血管造影：腹腔動脈からの造影では，直径1.5cmの左胃動脈瘤を認め（Fig. 2a），瘤よりも近位より分岐する左胃動脈分枝，瘤末梢から分岐する左肝動脈を金属コイルでisolationし，瘤内をNBCA（n–butyl–2–cyanoacrylate）により塞栓した（Fig. 2b）。 Celiac artery angiography showed a pseudoaneurysm of the left gastric artery and left hepatic artery. Transcatheter arterial embolization (TAE) was done successfully. Arterial flow for the aneurysm was shut out. 入院後経過：後日判明したmyeloperoxidase–anti–neutrophil cytoplasmic antibodies（MPO–ANCA）や，proteinase–3–anti–neutrophil cytoplasmic antibodies （PR3–ANCA）などの血管炎マーカーはいずれも陰性であり，微小動脈瘤形成の所見から，臨床的に節性動脈中膜壊死（segmental arterial mediolysis: SAM）と診断した。濃厚赤血球4単位の輸血投与と緊急IVR後は循環動態の安定が得られた。呼吸器症状も改善し第2病日から経口摂取を開始した。胸水の再貯留は認めず，その後も血胸が再燃することはなかった。IVR後大きな合併症なく経過は良好で，第22病日に独歩で退院した。その後発症から1年までの時点では，新たな動脈瘤の形成もなく経過している。 腹部内臓動脈瘤は比較的稀な疾患であり，その発生頻度は0.01～2%とされている。Stanleyらの腹部内臓動脈瘤1,118例の集計によると，脾動脈が最も多く656例（58.7%），次いで肝動脈が227例（20.2%），上腸間膜動脈瘤89例（7.9%）と続くのに対し，胃動脈瘤は53例（4.7%）であると報告されている 3。 腹部内臓動脈瘤の成因としては，動脈硬化，神経線維種症I型やEhlers–Danlos症候群などの先天性疾患，腹部外傷，ベーチェット病や高安病，多発血管炎などの膠原病，正中弓状靭帯圧迫症候群，慢性膵炎などの炎症性疾患などがあるが，近年画像診断の進歩に伴って，SAMが注目されている 4。SAMは1976年にSlavinらにより提唱された疾患概念 5で，腹部内臓動脈の中膜が分節性に融解し動脈瘤を呈する病態である。稲田らの報告によると，SAMと診断された患者の35.7%に多発動脈瘤を認めており，一般的には異所性，異時性に動脈瘤を形成することが多いとされている 6。 SAMの確定診断は切除標本からの病理学的診断によってなされていたが，近年，画像診断の進歩や開腹手術と比較して低侵襲であるIVRが動脈瘤治療の第一選択となってきており，病理学的確診が得られる機会が少なくなってきた。内山ら 7は腹部内臓動脈瘤の中で，①中高年の患者，②炎症性変化や動脈硬化性病変などの基礎疾患がない患者，③突然の腹腔内出血で発症，④血管造影で血管の数珠状の不正な拡張と狭小化を認める，の4項目をSAMの特徴とし，これに合致するものをSAMと診断する臨床的診断基準を提唱している。本症例においては，中年女性であること，非動脈硬化性，非炎症性であること，血管造影検査で左胃動脈だけでなく左肝動脈外側区領域にも動脈瘤を形成し，特徴的な数珠状変化も認めていたことから臨床的にSAMと診断した。 また，胃動脈瘤の中では左胃動脈瘤破裂が最も多く報告されている。医学中央雑誌による検索では，左胃動脈瘤破裂の本邦報告例は25例であり，いずれも腹腔内出血あるいは消化管出血によるショック症状で搬送されていた。海外においては，腹部内臓動脈瘤破裂に伴い胸水貯留を呈した症例についての報告 8, 9, 10が散見される。一般に，腹部内臓動脈瘤破裂は血性腹水の貯留を認めるが，本症例の場合は血胸を呈していた。横隔膜を隔てた液体成分の移動に関して，腹腔内圧の上昇に伴い，横隔膜小孔を通じて胸腔内へ液体成分が漏出した症例報告がみられる。本症例では，滑脱型食道裂孔ヘルニアが存在し，腹腔内における血腫が食道裂孔を介して腹腔から縦隔へ連続していた。食道裂孔は伸縮性を持つ約3cmの筋性管で，左右の横隔膜脚内側縁により境界される。食道裂孔を形成する筋束は右脚の内側部から送られ，これが食道を包むようにめぐっており，下部食道～胃噴門部は横隔食道膜という靭帯に固定されている。食道裂孔ヘルニアとは，加齢によりこの横隔食道膜が弛緩することにより胃の一部が胸腔側に逸脱した状態である。食道は漿膜を持たず，周囲は疎な結合組織と脂肪組織に覆われているため，食道胃接合部手術における剥離は容易である。また，右胸腔とは薄い食道臓器鞘で接していることから，剥離操作時には右胸腔開放に注意を要する。腹部内臓動脈瘤破裂症例で，合併する食道裂孔ヘルニアを通じて胸腔穿破，胸水貯留を来した報告は少数にみられ 11, 12，食道裂孔ヘルニア内の胃穿孔から縦隔気腫や膿瘍を形成した報告例 13もある。また，慢性膵炎における仮性膵嚢胞で，嚢胞が後腹膜を頭側へ進展することで食道裂孔を貫き，胸腔へ穿破，内瘻を形成したことで膵性胸水貯留を来した症例も報告されている 14。食道裂孔部が弛緩した状態では，食道周囲の結合組織が疎であることによる血腫の下縦隔への進展，そこに接する胸膜穿破が起こりうると考える。本症例は，画像診断では血胸の原因となる病変を肺，胸膜，食道に認めず，単回の胸腔穿刺ドレナージとIVRによる止血術で血胸の再燃を認めなかった。左胃動脈瘤破裂による出血が，腹腔内の圧が上昇したことで，最も抵抗の少ない食道裂孔ヘルニア部から疎な結合組織を通じて縦隔へ進展し，壁側胸膜を穿破して血胸に至ったものと推測した。 右血胸を伴い出血性ショックを呈した左胃動脈瘤破裂の症例を経験した。腹腔内を出血源とする血液が，食道裂孔ヘルニアを介して主に胸腔内へと進展した可能性が考えられた。 共著者全員が利益相反はない。

孤立性特発性腹腔動脈解離に続発した解離性脾動脈瘤破裂の2例(Ruptured dissected splenic artery aneurysms secondary to isolated spontaneous celiac artery dissection: a report of two cases)

【症例1】52歳の男性。腹痛を主訴に近医を受診したところ，腹部造影CTで急性膵炎および脾動脈瘤破裂と診断され当院紹介となった。当院CTでは腹腔動脈起始部の解離と仮性動脈瘤を認めた。血管内治療を試みたが，脾動脈遠位の屈曲・蛇行が強く，金属コイルとNBCA併用による近位塞栓で終了とした。不完全塞栓であったため最終的には手術治療を要した。【症例2】53歳の男性。受傷2日前に突然の腹痛を自覚。受傷当日，乗用車運転中に意識消失し対向車と正面衝突し搬送となった。来院時ショック状態であり，腹部超音波検査では腹腔内液体貯留を認め，造影CTでは腹腔動脈起始部より脾動脈遠位に至る偽腔開存型解離および解離性脾動脈瘤破裂と周囲血腫を認めた。腹腔動脈起始部は正中弓状靱帯圧迫症候群により狭小化していた。血管内治療を施行したところ，脾動脈解離の真腔は偽腔に圧排され完全閉塞し，偽腔より横隔脾間膜内への造影剤漏出を認めた。偽腔の近位・遠位を金属コイルで塞栓し止血を得た。経過観察後のCTでは脾門部に仮性動脈瘤の出現を認め，金属コイル・NBCA塞栓術を追加し根治し得た。孤立性特発性腹腔動脈解離に伴う解離性脾動脈瘤破裂は非常に稀ではあるが，内因性腹部出血の鑑別の一つとして考慮すべきであり，発症様式や全身状態により各施設で最適な止血方法を選択する必要がある。 Here we report the features of two cases of ruptured dissected splenic artery aneurysm associated with isolated spontaneous celiac artery dissection encountered in our institute. Case 1: A 52–year–old male was referred to us following diagnosis with acute pancreatitis with pancreatic pseudocyst, dissection of the origin of the celiac artery, and a dissecting pseudoaneurysm of the splenic artery on computed tomography(CT). Endovascular treatment was attempted, but the distal splenic artery was difficult to reach due to high flexion and tortuosity; therefore, proximal embolization alone was performed. Follow–up CT showed incomplete embolization, and radical surgical treatment was subsequently performed. Case 2: A 53–year–old male lost consciousness while driving a passenger car and was injured in a head–on collision with an oncoming car. CT showed dissection from the origin of the celiac artery to the proximal splenic artery and rupture of the splenic artery aneurysm. The celiac artery was narrowed due to median arcuate ligament syndrome. Endovascular treatment was performed, the proximal and distal portions of the false lumen were embolized with coil and cyanoacrylate, and hemostasis was achieved. Follow–up CT revealed a pseudoaneurysm at the splenic hilum, and embolization was performed again. Although, very rare cases, we should consider as one of the differentials diagnoses. 孤立性特発性腹部内臓動脈解離は稀な病態であるが，腹腔動脈解離は上腸間膜動脈解離に次いで多いとされている 1。孤立性特発性腹腔動脈解離（isolated spontaneous celiac artery dissection: ISCAD）はmulti detector–row CT（MDCT）の普及により報告数が近年増加しているものの，無症候から症候性に至るまで臨床経過は様々である。一般的には初回治療として保存的治療を選択することが多いが，合併症を有する例では侵襲的治療が選択される 2。今回我々は，解離性脾動脈瘤破裂を伴ったISCADの2例を経験したため，文献的考察とともに報告する。 本稿は倫理委員会の承認を要しない症例報告である。また，個人情報保護法に基づき匿名化されており，患者家族から論文の出版に関する同意を得ている。 患 者：52歳の男性 主 訴：左側腹部痛 既往歴：特記事項なし 飲酒歴：焼酎500〜1,000mL/日 喫煙歴：20〜30本/日×30年間 現病歴：来院10日前より左側腹部痛を自覚していたが，徐々に増悪したために前医へ救急搬送された。造影CT検査で急性膵炎および脾動脈瘤破裂と診断され，当院へ転送となった。 来院時現症：意識レベルJapan coma scale（JCS）I–0，Glasgow coma scale（GCS）E4V5M6，呼吸数18/分，心拍数110/分，血圧140/80mmHg，体温37.2℃（腋窩），SpO2 100%（室内気）腹部は平坦・軟であり左側腹部の自発痛はほぼ消失していた。血液検査では白血球17,000/μL，CRP 6.92mg/dLと軽度の炎症所見を認めた。Amyは70U/Lと基準値内であった。 腹部造影CT動脈相では，腹腔動脈起始部は解離しておりISCADの所見を認めた（補足図1a）。動脈解離は腹腔動脈から脾動脈中程まで連続しており，脾動脈起始部は偽腔に圧排され高度に狭小化しており，偽腔は瘤状に拡張していた。さらに，破裂した偽腔周囲には最大径約25mmの不整に拡張した仮性動脈瘤を認めた（補足図1b）。また，膵体尾部の腫大と膵周囲の脂肪織濃度上昇を認め，急性膵炎の所見を認めた（補足図1c）。 初療経過：循環動態は安定していたため，仮性動脈瘤に対し動脈塞栓術（transcatheter aterial embolization: TAE）の方針とした。腹腔動脈造影では，腹腔動脈起始部から脾動脈へ及ぶ解離を認め，解離性脾動脈瘤を形成していた。解離性脾動脈瘤の周囲には最大径47mmの血腫を認め，仮性動脈瘤を形成していた（補足図2a）。脾動脈の真腔は拡張した偽腔に圧排されて狭小化しておりアプローチ不能であったため，偽腔よりアプローチした。偽腔から解離性脾動脈瘤遠位の選択を試みたが，屈曲と蛇行が強く困難であった。そのため，アイソレーションを断念し，仮性動脈瘤に連続する解離性脾動脈瘤内をコイル6本でパッキングし，解離性脾動脈瘤近位に2本のコイルを留置して50%NBCA 2mLを注入した。NBCAは解離性脾動脈瘤の尾側に停滞した。その後の造影では，解離性脾動脈瘤の一部に造影効果を認めたが，これ以上の塞栓は技術的に困難と判断し手技を終了した（補足図2b）。 入院後経過：TAE後は腹痛の再燃や貧血の進行なく経過したが，第4病日の造影CTではコイル塞栓部腹側に結節状の造影効果が残存し，塞栓部の遠位にも血流を認めた（補足図2c）。不完全塞栓であったがTAEによる再アプローチは困難と考え，待機的に第8病日に手術となった。開腹時，活動性出血はほぼ認めなかった。膵体尾部に膵炎の影響と思われる高度癒着を認め，瘤との剥離は困難であった。脾動静脈を根部で結紮し，膵体尾部・脾臓合併切除を行った（補足図3a, b）。術中出血量2,320mL，濃厚赤血球輸血計4単位使用した。術後経過は良好で第25病日に退院となった。切除膵の病理組織診断では，膵炎の炎症が脾動脈へ波及し，脾動脈外膜が破壊されている所見を認めた。 患 者：53歳の男性 主 訴：意識消失，腹痛 既往歴：糖尿病，高血圧 現病歴：受傷2日前の早朝に突然の激しい腹痛とめまいを自覚したが，自宅で様子を見ていた。受傷当日，乗用車を運転中に意識消失感が出現し，車を停車させたところで対向車と正面衝突し救急要請となった。救急隊接触時ショック状態であり，ドクターヘリで当院搬送となった。 来院時現症：意識レベルJCS I–1，GCS E4V5M6，呼吸数18/分，心拍数121/分，血圧81/54mmHg，体温35.2℃（腋窩温），SpO2 99%（酸素10Lリザーバーマスク），瞳孔径は両側3.0mmで対光反射は迅速であった。腹部超音波検査でモリソン窩，脾周囲，膀胱直腸窩に液体貯留を認めた。体表上は明確な外傷痕は認めず，腹部も平坦軟であったが，上腹部に軽度の圧痛を認めた。血液・生化学検査では，白血球の上昇（25,100/μL）と貧血（Hb 10.2mg/dL）を認めたほか，Cr 1.08mg/dL，CRP 2.29mg/dL，乳酸32mg/dLと上昇を認めた。Amyは110U/Lと基準値内であった。 初療経過：ドクターヘリ医師接触時は血圧測定不能であったが，現場より初期輸液，O型赤血球輸血開始後，来院時収縮期血圧は80mmHg以上に上昇したため，直ちに腹部造影CTを施行した。腹部造影CTでは血性腹水貯留を認め，腹腔動脈起始部は正中弓状靱帯圧迫症候群（median arcuate ligament syndrome: MALS）により狭小化（補足図4a）しており，かつ解離（ISCAD）を認めた（補足図4b）。ISCADは脾動脈遠位に及び，解離性脾動脈瘤の破裂に伴う仮性動脈瘤が形成されていた。さらに，横隔脾間膜内には大量の血腫を伴っていた（補足図4c）。来院時は、“外傷性”腹腔内出血として初療を進めていたが，受傷機転が軽微なこと，腹部に外傷痕を認めないこと，来院2日前からの腹痛と意識消失のエピソードがあることを考慮し，解離性脾動脈瘤破裂による出血性ショックと最終的に判断した。開腹止血術も考慮したが，輸液・輸血により循環動態の安定化が得られたこと，CT上腸管損傷などの絶対的に手術介入を要する病態がないことからTAEの方針とした。腹腔動脈造影では仮性動脈瘤はやや遅れて描出された（補足図5a）。膵尾枝や大膵動脈は描出されず，遠位で僅かに脾実質が造影された。腹腔動脈造影を施行したところ，腹腔動脈解離に続く解離性脾動脈瘤の真腔は偽腔に圧排されて狭小化し，完全閉塞していた。そのため，偽腔内へガイドワイヤーを進め，偽腔内から仮性動脈瘤の遠位をコイル計5本，近位をコイル計7本にてアイソレーションした（補足図5b）。最終的に腹腔動脈造影，上腸間膜動脈造影で仮性動脈瘤が描出されないことと，短胃動脈から脾実質の造影効果が保たれていることを確認して手技を終了した。 入院後経過：循環動態は安定して経過し，貧血進行もなく，止血は得られたと判断した。第8病日の造影CTでは，脾門部に短胃動脈を血液流入路とする仮性動脈瘤の出現を認めた。瘤径は小さく血栓化を期待し経過観察を行ったが，第18病日のCTで瘤径14×16mmと増大を認めたため再度TAEを施行した。腹腔動脈から胃十二指腸動脈，胃大網動脈を介してアプローチし，仮性動脈瘤近位と遠位で金属コイル2本と40%NBCAにて塞栓を行った（補足図6a, b）。脾臓血流は，短胃動脈・後胃動脈を介して温存された。その後は経過良好で，第21病日に退院となった。 今回我々は，ISCADを伴う解離性脾動脈瘤破裂の症例で，それぞれ異なる治療アプローチを要した2症例を経験した。ISCADはMDCTの普及により近年報告数が増加しており，初回治療として降圧，鎮痛，抗血小板療法，抗凝固療法などによる保存的治療を選択されることが多い。腹腔内出血などの合併症を有する例では侵襲的治療が選択されるが，確立した治療法はなく，症例により手術あるいは血管内治療が選択されている 2, 3, 4。 侵襲的治療の適応として，症状持続，腹腔動脈径拡大（≧15～20mm）や瘤化，真腔の狭小化や閉塞による臓器虚血，動脈瘤破裂が挙げられる 5。ISCAD 169例のシステマティックレビューでは血管内治療が11.8%に，開腹手術が8.9%に行われており，近年では血管内治療が主流となっている 6。また，別のシステマティックレビュー（68症例）では，解離の進展範囲に関し腹腔動脈限局が22.6%，脾動脈への進展が50.9%，総肝動脈への進展が45.3%と報告されている 5。破裂症例は腹腔動脈1.2%，脾動脈2.9%に認め全例死亡している 5, 6。このように，ISCADから破裂に至る症例は非常に稀であり，文献検索した範囲では腹腔動脈起始部の解離が遠位へ進展し破裂した例は4例のみであった 2, 3, 7, 8。 今回提示した2症例では，ISCADが脾動脈遠位まで解離を来し，かつ解離性動脈瘤破裂に至った点と，その背景にそれぞれ膵炎やMALSを有していた点で非常に稀な症例であった。これまでにISCADの成因として，動脈硬化，血管炎，線維筋性異形成，結合織疾患（Marfan，Ehlers–Danlos症候群），結節性多発動脈炎，segmental arterial mediolysis，梅毒や真菌感染症などが報告されている 2。 症例1では，循環動態が安定していたことからTAEを第一選択としたが，脾動脈の屈曲・蛇行と狭小化が著しく，不完全塞栓となり最終的に手術を要した。ISCADの解離が脾動脈へ進展した結果解離性脾動脈瘤を形成し，さらに脆弱性の高い偽腔に急性膵炎の炎症が波及し破裂を来し，仮性動脈瘤を形成したものと考えられた。ISCADそのものの成因として膵炎が背景となっていたかに関しては報告が存在しない。症例2は，MALSに続発したISCADが脾動脈に進展し，解離性脾動脈瘤の形成から破裂に至った症例であった。MALSがISCADの発生に関与した症例は過去に報告されており，MALSに腹腔動脈解離が合併し膵十二指腸動脈瘤破裂に至った例 9や，MALSに腹腔動脈解離を伴い血管内治療を施行した例 10，および血管内治療に加え腹腔鏡による弓状靭帯切離を施行した例 11の3症例のみが存在している。MALSからISCADを生ずる機序は，腹腔動脈起始部の物理的狭小化によって血管内腔の圧上昇を来し，内膜と中膜の解離を生じるためと考えられる。無症候性のMALSが多く存在することは知られており，剖検例の検討では約1/3にMALSによる腹腔動脈圧迫を認めたとの報告もある 12, 13。また，CTなどの画像検査で約7%に腹腔動脈の無症候性狭窄が発見されたとの報告もある 14。ゆえに，症例2のように無症候性のMALSにISCADを潜在的に有している例も少なからず存在する可能性がある。なお，CTでISCADが偶発的に見つかった場合でも，循環動態が安定しており破裂や仮性動脈瘤を伴っていない場合にはルーチンでの血管造影は不要であり，MDCTでの形態的評価と経時的な経過観察で十分と考える。症例2ではTAEを第一選択としたが，もし仮に初期輸液にて循環動態の安定化が得られなかった場合，CT撮像ができないまま外傷性腹腔内出血として開腹止血術を先行させていた可能性があり，その場合ISCADによる内因性の解離性脾動脈瘤破裂との診断がつかなかった可能性がある。このように内臓動脈瘤破裂は，発症様式や全身状態においても選択される治療法が異なる病態であり，施設のリソースや各科のバックアップ体制なども考慮し，個々の施設で最適な止血方法を選択する必要があると考える。血管内治療，外科的治療のいずれを選択するにしても，初療を担う救急医がリーダーとして治療方針を決定し，専門的治療につなげることが要求されるため，内因性腹部出血の鑑別の一つとして常にこのような病態を念頭に置く必要がある。 また，MALSにおいては，根本原因である弓状靭帯圧迫を解除しないと，腹腔動脈，脾動脈塞栓に伴い，理論的に側副路への負担が増し将来的に瘤化から破裂を来す危険が残存する。現在ではより低侵襲な腹腔鏡下切離術が可能であり，ステントグラフト治療と組み合わせた根治的治療が将来的に期待されよう。 ISCADによる解離性脾動脈瘤破裂の2例を経験した。内因性腹部出血の鑑別としてISCADの破裂を念頭に入れる必要がある。 本稿における利益相反はない。 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A Case of Suspected Ruptured Left Gastric Artery Aneurysm due to Segmental Arterial Mediolysis

A Case of Suspected Ruptured Left Gastric Artery Aneurysm due to Segmental Arterial Mediolysis

S2686 A Rare but Potentially Fatal Cause of Abdominal Pain: Segmental Arterial Mediolysis

Introduction: Segmental arterial mediolysis (SAM) is a rare disease, defined as a nonatherosclerotic, noninflammatory disruption of the arterial medial layer of a medium- to large-sized artery. We describe a case of a healthy woman with acute onset abdominal pain subsequently found to have spontaneous peritoneal hemorrhage from SAM. Case Description/Methods: A 52-year-old former professional female athlete developed abrupt onset lower abdominal pain with nausea and vomiting. Pain was 10/10 in severity with a sharp and crampy quality. She denied fevers, diarrhea, melena, bloody stool, ill contacts, recent travel, or prior episodes. Past medical history was significant for endometrial polyp, menopause, and iron deficiency. She had no prior surgeries. Family history included colon cancer in her father and ovarian cancer in her mother. Her abdomen was soft with tenderness in the lower quadrants with the remainder of the exam unremarkable. Labs including CBC, BMP, LFT, lipase, beta hCG, troponin, ESR, CRP, serum acetone, urinalysis, and lactic acid were reassuring. CT abdomen and pelvis with and without contrast demonstrated hyperenhancing hepatic lesions suggestive of hemangiomas. Ultrasound of the pelvis with duplex was normal with arterial and venous duplex waveforms to both ovaries. On the second day of hospitalization, she had another episode of abdominal pain with labs demonstrating a hemoglobin drop from 13.7 g/dL to 10.2 g/dL. Repeat CT abdomen pelvis with contrast demonstrated large volume hemorrhagic ascites up to 16 cm in size with concerns for active hemorrhage in the left upper quadrant. Diagnostic angiography was performed by Interventional radiology which did not show active arterial hemorrhage although demonstrated fusiform dilatation of the distal middle colic artery and short segment focal fusiform dilatation of the left colic artery at the splenic flexure suggestive of SAM. She subsequently underwent diagnostic laparoscopy and evacuation of hemoperitoneum with over 1L of unclotted blood evacuated with a mesenteric hematoma noted in the distal transverse and proximal descending mesocolon. The spontaneous peritoneal hemorrhage was thought to be secondary to underlying arterial abnormalities triggered by minor trauma. (Figure) Discussion: Vascular causes of abdominal pain such as segmental arterial mediolysis are uncommon. Awareness of noninflammatory and nonatherosclerotic artery diseases such as SAM need to be recognized since they can be fatal if not treated promptly.Figure 1.: Fig 1 demonstrates a bleeding artery as seen on CT abdomen and pelvis with intravenous contrast. Fig 2 demonstrates the large hemoperitoneum in the left upper quadrant seen on CT abdomen and pelvis.

S3319 An Unusual Presentation of Segmental Artery Mediolysis

Introduction: Segmental Arterial Mediolysis (SAM) is a rare non-atherosclerotic and non-inflammatory disease that often mimics vasculitis. It most commonly affects celiac artery and superior mesenteric artery. Here we describe an unusual presentation of SAM in an elderly woman. Case Description/Methods: A 65-year-old female with history of smoking presented with sudden onset dull epigastric pain, radiating to the back, nausea, vomiting and decreased oral intake for three days. Review of system was negative for other symptoms. Vital signs upon presentation were blood pressure 140/87 mm Hg, heart rate 92 beats per minute, respiratory rate 16 per minute and saturating 96% on room air. Physical examination revealed epigastric tenderness without rebound tenderness or guarding. Initial labs showed WBC 15,200/mL, CRP 9.4 mg/L and ESR 92 mm/hour. LFTs revealed AST 2173 U/L, ALT 2013 U/L, total bilirubin 0.6 mg/dl, albumin 3.7 and INR 1.1 Further labs ruled out infectious etiology for her presentation. Rheumatologic work up was negative for ANA, ANCA or abnormalities in complement proteins. Computed tomographic angiography (CTA) of the abdomen demonstrated multiple large aneurysms involving bilateral hepatic arteries with diffuse irregularity and ectasia of the hepatic arterial system and blood products surrounding the left hepatic artery aneurysm. (Figure A) She subsequently underwent coil embolization of left hepatic artery. (Figure B) The procedure was complicated by complete occlusion of left hepatic artery and spontaneous thrombosis of right hepatic artery upon catheterization. CTA abdomen after procedure showed reconstitution of flow within hepatic arterial supply via collaterals. Post procedure investigations revealed down trending inflammatory markers and transaminitis with levels returning to baseline within a week. Discussion: To the best of our knowledge, this is the first reported case with multiple pseudoaneurysms involving both hepatic arteries. Although, in our case, histologic confirmation was not done, clinical presentation, laboratory findings and radiologic pattern, led to the diagnosis of SAM. Early detection is the key in the prognosis of SAM, as clinical course tends to be unpredictable and complications of vascular injury including stenosis, dissection, aneurysm or rupture may occur.Figure 1.: A) Computed tomographic angiography (CTA) of the abdomen demonstrated left hepatic artery aneurysm (arrowhead) and right hepatic artery aneurysm (arrow). B) Angiogram showing coil embolization of left hepatic artery (arrow).

Mesenteric Artery Dissection and Wall-Thickening, Case Study and General Review.

Mesenteric artery dissection (D) and wall-thickening (WT) are rare vasculopathies that can lead to serious complications. This is a single center analysis of all patients evaluated for mesenteric arterial (celiac, superior (SMA) and/or inferior mesenteric (IMA)) D and/or WT from January 1, 2000, to January 31, 2020 at our hospital. Among the 101 included patients, the average age was 55.6 ± 13.6years, mostly affecting men (62%). There were 20 celiac artery D, 8 WT, 15 D with WT, 15 SMA D, 7 WT, 8 D with WT, one IMA D, two WT, and 25 with multiple arterial involvement. Primary etiologies included segmental arterial mediolysis (SAM) (n = 17), isolated D (n = 17), localized vasculitis of the gastrointestinal tract (LVGT) (n = 16), fibromuscular dysplasia (FMD) (n = 13), extension of thoracoabdominal aortic D (n = 12), and trauma (n = 12). Most (71%) patients presented with abdominal pain. Hypertension (55%), hyperlipidemia (33%) and tobacco use (31%) were prevalent. Management included conservative (22%), medical (47%), endovascular (19%), and/or open repair (12%) with high in-hospital survival (98%) and symptom relief (73%). Our paper complements the scarce literature addressing the diagnosis and management of rare mesenteric vasculopathies. Most patients improved with conservative management, reserving endovascular or surgical interventions for symptomatic patients with more complicated presentations.

Intra-abdominal hemorrhage due to segmental arterial mediolysis of an ovarian artery pseudoaneurysm and concomitant aneurysmal subarachnoid hemorrhage: illustrative case.

Aneurysmal subarachnoid hemorrhage (SAH) is one of the most severe neurosurgical diseases in which systemic management is important from the acute phase to the chronic phase. The authors reported a case of aneurysmal SAH associated with intra-abdominal hemorrhage possibly caused by segmental arterial mediolysis (SAM). A 60-year-old woman collapsed suddenly at home. On arrival at our hospital, she was comatose and her head computed tomography (CT) showed SAH, probably from an anterior cerebral artery aneurysm. Simultaneous body CT to screen for pneumonia associated with COVID-19 incidentally detected an intra-abdominal hematoma and the bleeding point. Emergent ventriculostomy was conducted first. Because abdominal angiography detected a ruptured pseudoaneurysm of an ovarian artery, emergency embolization was subsequently performed for hemostasis. However, she deteriorated again, and her pupils became fully dilated. The patient died on day 3 of hospitalization. Patients with aneurysmal SAH rarely have intra-abdominal hemorrhage in the acute stage and may have a fatal outcome. Intra-abdominal hemorrhage should be suspected in the setting of unstable vital signs, and prompt treatment is necessary.

Segmental Arterial Mediolysis of the Abdominal Vessel: A Case Report

Segmental arterial mediolysis (SAM) is a rare but serious arteriopathy of unknown etiology with life-threatening manifestation. It is characterized by lysis of the medial layer of the arterial wall and may result in dissection, stenosis, occlusion, and aneurysm formation. We would like to report a case of SAM that occurred in the hepatic and visceral arteries and caused the ischemia.

Intra-abdominal Bleeding due to Segmental Arterial Mediolysis and Coexisting Pulmonary Thromboembolism: a Case Report

Segmental arterial mediolysis (SAM) is a rare but important cause of abdominal haemorrhage and is usually treated with endovascular management. Surgical or conservative management can be performed depending on the patient’s situation. Since the course of conservative treatment is not well described in the existing literature, it must be used with caution. We describe the case of a 52-year-old man who was transferred to the emergency department because of abdominal pain, diarrhoea, and haematemesis. On arrival, he was haemodynamically unstable, with a blood pressure of 70/40 mmHg. After he was transfused and stabilised in the emergency department, contrast-enhanced computed tomography (CECT) revealed a haematoma around the transverse colon and ascites, without any evident extravasation. The peripheral branch of the middle colic artery (MCA) showed irregular calibre, suggesting SAM. Since the patient remained stable, we initially chose conservative management. However, a CECT scan performed on the third day of hospitalisation showed coexisting pulmonary thromboembolism (PTE). Because of the need for anticoagulation therapy, we performed open surgery. The pathological examination was consistent with SAM. Anticoagulation therapy was initiated the next day. A CECT scan performed on a postoperative day (POD) 13 showed no PTE. Although the patient defecated haemorrhagic stool and experienced hematemesis on PODs 19 and 23, respectively, colonoscopy, esophagogastroduodenoscopy, and repeated CECT scans revealed no evidence of rebleeding, and no recurrence was observed. Open surgery produced a relatively good postoperative course for the patient. Endovascular management, however, remains a reasonable first approach, considering its reportedly excellent outcomes.

Splenic Artery Pseudoaneurysms: The Role of ce-CT for Diagnosis and Treatment Planning

Splenic artery pseudoaneurysm (PSA) is a contained vascular wall lesion associated with a high mortality rate, generally related to pancreatitis, trauma, malignancy, iatrogenic injury, and segmental arterial mediolysis. Computed tomography angiography allows us to visualize the vascular anatomy, differentiate a PSA from an aneurysm, and provide adequate information for endovascular/surgical treatment. The present review reports on the main state-of-the-art splenic artery PSA diagnosis, differentiating between the pros and cons of the imaging methods and about the endovascular treatment.

Segmental Arterial Mediolysis: A Multiguised Vasospastic Arteriopathy with Collateral Mesangial Cell Hyperplasia and Cardiac Toxicity Generated by Norepinephrine and Hyperdense Adrenoceptors Alone or by Crosstalk with Other Pressor Agents.

Segmental arterial mediolysis (SAM), an uncommon vasospastic arteriopathy occurring in the muscular arteries innervated by the peripheral sympathetic nervous system, usually presents with catastrophic abdominal and retroperitoneal hemorrhages in elderly patients. SAM is initiated by the coupling of norepinephrine to plastically derived hyperdense foci of alpha-1 adrenergic receptors on the sarcolemma of arterial muscle. This ligand is created by stimuli signaled by iatrogenic sympathomimetic agonists, some beta-2 agonists, or an excessive release of adrenal catecholamines. Coupling of this ligand with cytoplasmic heterotrimeric Gq protein excessively signals a cascade of biochemical events generating two principal lesions of injurious-phase SAM—the shearing of the outer media from the adventitia and an overload of cytoplasmic calcium ions toxic to mitochondria causing mediolysis and/or apoptosis. The massive hemorrhages are caused by ruptured gap aneurysms created by the transmedial loss of the medial muscle. A norepinephrine-directed reparative response rapidly develops either resolving angiographic injurious lesions or creating a body of vascular disorders, the new guises of SAM with ischemic clinical profiles. These present in the epicardial, vertebral, intestinal, and retroperitoneal arteries, often in younger females as fibromuscular dysplasia, dissecting hematomas, and persistent aneurysms. Norepinephrine can crosstalk with other pressor agents to create SAM lesions—serotonin with idiopathic pulmonary hypertension and persistent pulmonary hypertension in the newborn, histamine in spontaneous coronary artery dissections with eosinophilia, and endothelin-1 in a field effect generated by SAM that creates venous fibromuscular dysplasia. Norepinephrine also participates in the collateral development of mesangial hyperplasia with focal segmental glomerulosclerosis and myocardial mediolysis and apoptosis in subjects with markedly elevated heart rates. Conclusion. Norepinephrine coupling with plastically elevated alpha-1 adrenoceptor or other pressor agents generates SAM, a histologically recognizable vasospastic arteriopathy, that with repair is transformed into several different standardized arterial diseases that alter SAM's clinical profile from a hemorrhagic to an ischemic disorder.

A Single Center 8 Year Experience of Segmental Arterial Mediolysis Management

Segmental Arterial Mediolysis (SAM) is a rare, poorly understood vasculopathy that involves vacuolization of the arterial wall, most commonly of the visceral arteries. There are no established therapeutic or monitoring guidelines for SAM, and intervention typically depends on patient presentation. The purpose of this study is to review the management and outcomes of patients with this rare vascular disease METHODS: Single center retrospective review of patients diagnosed with SAM between 2011 and 2019. Included were patients with radiological diagnosis of SAM. Demographic factors, past medical history, presenting symptoms, affected vessels, management, and lesion characteristics over time were collected. Demographic and periprocedural factors, and medical management strategies were compared for those who required operative intervention versus those managed non-operatively. Thirty patients were included, 21 (70%) were male, mean age was 53.5 years (range: 35.7-72.2). Twenty-seven patients were managed non-operatively, 3 patients required surgical intervention. Patients who underwent operative intervention were more likely to present with pain >30 days (P < 0.05), and hemorrhage (P < 0.01). Abdominal pain was the most common presenting symptom (n=24, 80%). Arterial dissection was the most common radiological finding at time of presentation (n=20, 67%). The celiac artery and its branches were most often involved (n=22, 73%) followed by the superior mesenteric artery and its branches (n=15, 50%). Non-operative management most often consisted of anti-hypertensive therapy (n=13, 43%), antiplatelet agents (n=17, 57%%), and lipid-lowering agents (n=13, 43%), with 7 patients receiving all three. Six patients demonstrated confirmed resolution of lesions during surveillance imaging, with average time to resolution of 325.5 days. Patients who underwent intervention for SAM presented with either mesenteric ischemia or pseudoaneurysm rupture. In patients that present without those conditions, medical management consisting of anti-hypertensives, antiplatelet agents, and lipid-lowering therapy was effective. Non operative management resulted in symptom resolution in all patients and surveillance imaging showed resolution of radiographic abnormalities in 6 patients out of 27 at less than one year.

Clinical Presentation, Imaging, and Management of Segmental Arterial Mediolysis: A Rare Vascular Disorder.

Objectives Our objective was to analyze the clinical presentation, imaging findings, and the management of segmental arterial mediolysis (SAM) in different case scenarios within our medical institution. Materials and Methods We retrospectively analyzed 13 cases of SAM in our institution from July 2017 to March 2020. The images from the cases were collected from picture archiving and communication system (PACS) along with other pertinent clinical information from the hospital's information system. All the patients we studied underwent contrast-enhanced computed tomography (CT) using a third-generation Siemens SOMATOM Force dual-source CT scanner. Once the dual-phase scanning was completed, the images were analyzed using the workstation's syngo.via software. Results Three out of the 13 cases required stent-grafting of the renal/celiac artery, and the involved branch of the superior mesenteric artery was embolized in one case. The rest of the cases were managed conservatively with antiplatelets/anticoagulants. Subsequent follow-ups of the patients were conducted and showed stabilization/regression of the initial findings without finding any evidence of worsening. Conclusion SAM should be considered when making a differential diagnosis of acute abdominal pain when associated with dissection or aneurysms in splanchnic arteries, and in cases of unexplained intra-abdominal hemorrhaging. The radiologist needs to be aware of this possibility to raise suspicion, alert the clinician, and guide appropriate management.

Rapid Formation and Rupture of Multiple Abdominal Pseudoaneurysms: A Life Threatening Case of Segmental Arterial Mediolysis.

We present a 62-year-old gentleman with rapidly forming abdominal pseudoaneurysms due to segmental arterial mediolysis (SAM). With rupture of his pseudoaneurysms, he underwent angiography and successful coil embolisation. In this case, we demonstrate the potential for rapid progression of pseudoaneurysms in SAM, with the need for prompt diagnosis and urgent endovascular intervention.

Beyond Atherosclerosis and Fibromuscular Dysplasia: Rare Causes of Renovascular Hypertension.

Renovascular hypertension is one of the most common forms of secondary hypertension. Over 95% of cases of renovascular hypertension are due either to atherosclerosis of the main renal artery trunks or to fibromuscular dysplasia. These two causes of renal artery stenosis have been extensively discussed in recent reviews and consensus. The aim of the current article is to provide comprehensive and up-to-date information on the remaining causes. While these causes are rare or extremely rare, etiologic and differential diagnosis matters both for prognosis and management. Therefore, the clinician cannot ignore them. For didactic reasons, we have grouped these different entities into stenotic lesions (neurofibromatosis type 1 and other rare syndromes, dissection, arteritis, and segmental arterial mediolysis) often associated with aortic coarctation and other arterial abnormalities, and nonstenotic lesions, where hypertension is secondary to compression of adjacent arteries and changes in arterial pulsatility (aneurysm) or to the formation of a shunt, leading to kidney ischemia (arteriovenous fistula). Finally, thrombotic disorders of the renal artery may also be responsible for renovascular hypertension. Although thrombotic/embolic lesions do not represent primary vessel wall disease, they are characterized by frequent macrovascular involvement. In this review, we illustrate the most characteristic aspects of these different entities responsible for renovascular hypertension and discuss their prevalence, pathophysiology, clinical presentation, management, and prognosis.

Segmental arterial mediolysis with abdominal angina: case report

To report a rare case of a patient diagnosed with segmental arterial mediolysis with abdominal angina. The work is characterized as a Case Report with bibliographic review, the method used was the bibliometric analysis of articles published in the Pubmed database. The theoretical scan covered the years 2010 to 2020, and consisted of seeking out articles throughout all indexes using the terms: segmental arterial mediolysis and abdominal angina. The search occurred between the months of October and December of 2020. The information contained for the case report was obtained by the review of medical records, patient interview as well as records of laboratory tests and images. A 57-year-old man was diagnosed with segmental arterial mediolysis with abdominal angina after a series of investigations and imaging exams. These investigations were prompted due to a long- standing complaint of unexplained abdominal pain that had gone undiagnosed by other specialists. The evaluation of this pathology objectively requires the attainment of the earliest possible resolution, thus, cli entary investigations must be carried out. To date, however, there are no established guidelines on therapy.

Clinically Suspected Segmental Arterial Mediolysis of the Splanchnic Arteries: A Report of 2 Rare Cases

Case seriesPatients: Female, 89-year-old • Male, 52-year-oldFinal Diagnosis: Segmental arterial mediolysisSymptoms: Abdominal pain • bleedingMedication: —Clinical Procedure: —Specialty: RadiologyObjective:Rare diseaseBackground:Segmental arterial mediolysis (SAM) is an uncommon vascular pathology characterized by arteriopathy, mainly of medium-sized abdominal splanchnic vessels, without an atherosclerotic, inflammatory, infectious, or autoimmune underlying etiology. Segmental arterial mediolysis is clinically heterogeneous and symptoms may be completely nonspecific. The knowledge of radiological features of segmental arterial mediolysis and the exclusion of other pathologies should direct early diagnosis and refer patients for correct treatment.Case Report:In the last 2 years, we treated 2 different adult patients (an 89-year-old woman and a 52-year-old man) with spontaneous visceral bleeding, admitted to the Emergency Department due to acute onset of abdominal pain, anemia, and computed tomographic angiography (CTA) evidence of aneurysmatic, and stenotic alterations of splanchnic arteries. Based on clinical, laboratory, and radiological features, segmental arterial mediolysis was suspected. These 2 patients were referred to our Interventional Radiology Department and treated with super-selective transcatheter arterial embolization (TAE), performed by a minimally invasive approach, allowing an immediate clinical improvement with regression of symptoms and avoiding major surgical treatment.Conclusions:In patients with clinical, laboratory, and radiological signs of acute and/or chronic abdominal bleeding and radiological findings suggesting segmental arterial mediolysis, mini-invasive endovascular treatment is a safe, extremely reliable, and secure procedure and appears to be the first-choice treatment when available. Since abdominal bleeding could have fatal consequences in these patients, timely diagnosis and endovascular therapy are essential to treat visceral vascular alterations due to segmental arterial mediolysis.