sma thromboembolism - department of surgery at suny ...downstatesurgery.org/files/mesenteric...
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SMA Thromboembolism
Marc LaFonte PGY 4
SUNY Downstate June 18th, 2015
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Case Presentation
68 M generalized intermittent abdominal pain x 1 week, localized b/l lower quadrants +F, +BM non bloody, + anorexia, no association with meals No prior colonoscopy PMH: afib not on anti-coagulation PSH: non-contributory Social: smoker 1PPD x 40 years Meds: none NKA
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Physical Exam
Vitals: T 97.3F, BP 154/91, HR 62, RR 20, 95% RA AAOx3, NAD Abd: soft, non-distended, mild tenderness b/l lower abdomen Rectal: Guaiac negative, no masses
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Laboratory and Radiological Studies
13.7 > 15.1/48.4 < 192 143 / 3.1 | 97 / 25 | 14 / 1.02 < 197 LFT WNL, Lipase 29 Lactate 5.5 UA negative CXR: bibasalar atelectasis
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CT: Abdomen/pelvis Jejunal branch of SMA occluded R colic vein possibly occluded No portal venous gas, no thickened bowel no extravasation of PO contrast No free fluid
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Assessment and Plan
Admitted to SICU Started on heparin drip Aggressive IV hydration, broad spectrum abx Plan for mesenteric angiogram Pain worsened OR
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OR
Exploratory laparotomy – serous fluid Proximal small bowel perfused Extensive necrosis mid jejunum and mid ileum (total 150cm) - resected Remainder of jejunum and distal ileum viable SMA non-pulsatile, heavily diseased; SMV distended
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OR Continued
Transverse arteriotomy proximal to right colic, embolectomy. SMA tore, converted to longitudinal, Dacron patch placed Non-pulsatile SMA, patch incised, Fogarty passed, no clots GI left in discontinuity, abdomen left open, transferred to SICU
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Post-Operative Course
POD#0 profoundly hypotensive, crash laparotomy at bedside: patches of necrosis and ischemia of small bowel and R colon Made DNR Terminal extubation
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Questions?
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SMA Thromboembolism
•Spectrum of Mesenteric ischemia Syndromes
•Majority Heart
•Incidence 5.3 cases/100,000 •3:1 F:M •Age > 60
•Highly lethal: average mortality 69%
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“Occlusion of the mesenteric vessels is apt to be regarded as one of those condition of which … the diagnosis is impossible, the prognosis hopeless and the treatment almost useless.”
Dr. A. J. Cokkinis 1920’s
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Anatomy
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Anatomy •Early branches: Inferior PDA and middle colic artery
•Change caliber •Proximal jejunum to splenic flexure at risk
•Acute occlusion celiac or IMA more tolerated
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Anatomy
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Pathophysiology
Ischemia bowel mucosa Epi + Endothelial damage lose mucosal barrier Bacterial invasion, enzyme degradation inflammatory mediators microcirculatory stasis, edema intravascular thrombosis
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Presentation Acute Mesenteric Ischemia
•High index of suspicion
•Search for hx of dysrhythmias, MI, valvular disease, CHF, atherosclerosis, malignancy
•“Classic” sudden, epigastric/midabdominal pain out of proportion to exam, followed by defecation +/- blood
•+/- vomiting •When acute on chronic, may endorse anorexia, postprandial colicky pain, weight loss
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Physical Exam
•Subtle and nonspecific
•Vitals normal •Abdomen non tender or vaguely tender
•25% non tender •Distension, diminished bowel sounds •NGT lavage and rectal may show blood
•If patient looks toxic/peritoneal, bowel infarction and necrosis is already present
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Labs
•No test is sensitive or specific
• Possibly leukocytosis, hemoconcentration
•Late hints may include metabolic acidosis and lactate elevation, hyperkalemia
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Abdominal Radiograph
•Search for pneumoperitoneum, pneumoatosis intestinalis, portal venous gas
•Most commonly: adynamic ileus with a gasless abdomen
•Can help exclude obstruction, volvulus
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Other Imaging
• Duplex U/S
•Peak systolic SMA > 275cm/s (92% sen, 96% spec)
•CT angiogram: AP/lateral views •Meniscus sign from embolism to middle colic artery •May also show mesenteric vein “target sign”
•Upper endoscopy, colonoscopy not indicated •Barium contraindicated – obscures mesenteric circulation, if intraperitoneal can cause peritonitis and add challenges during revascularization
•**Mesenteric Angiogram**
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Initial Management
• Fluid resuscitation
•May have to add sodium bicarbonate if metabolic acidosis not improving
•Systemic anticoagulation (heparin)
•Prevents further thrombus propagation
•Broad spectrum antibiotics
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Surgical Treatment Principles: Thromboembolectomy
•Identify and remove gangrenous/perforated bowel to reduce soilage
•Locate cause of bowel loss •Compromise to jejunum, ileum, and colon = SMA occlusion at origin •Sparing of 1st portion of jejunum or patchy ischemia = emboli (or vasospasm)
• Plan for a second look at 24-48 hours
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Surgical Treatment: Acute Embolic Mesenteric Ischemia
Lift omentum and transverse colon cephalad Retract small bowel right, pack sigmoid left Divide LoT, mobilize duodenum Palpate SMA at base of transverse colon mesentery Confirm with doppler
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Surgical Treatment: Acute Embolic Mesenteric Ischemia
Expose 3-4cm SMA, palpate Transverse arteriotomy (planning to close) Longitudinal (bypass) Fogarty passed proximal and distal until negative clot Close arteriotomy
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Thrombotic Mesenteric Ischemia: Bypass Options and Principles
Usually involves at least 2 of 3 mesenteric arteries In acute setting, aortomesenteric revascularization expeditious and durable Non-acute, two-vessel revascularization to the SMA from aorta Inflow sites include iliacs, supraceliac or infrarenal aorta Choose conduit based on clinical scenario (autogenous vs. prosthetic) Wait 30 minutes after revascularization to re-assess bowel Adjuncts include Doppler (anti-mesenteric border) or fluorescence under Wood lamp
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Bypass Options: Antegrade Aortomesenteric
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Bypass Options: Retrograde Aortomesenteric
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Bypass Options: Ileomesenteric
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Endovascular Options
Used in setting of chronic mesenteric ischemia Indication primary stent placement (not clearly defined) Calcified ostial stenosis High grade eccentric stenosis Residual stenosis >30% Dissection after angioplasty In acute setting: Indicated when presentation within 12 hours symptoms Big drawbacks Inability to assess bowel Prolonged time for success
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•Journal of Vascular Surgery 2002 •1990-2000
•Retrospective Mayo Clinic
•58 patients •Embolic (28%) •Thrombotic (64%) •Non-occlusive (8%)
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•Presentation: •95% severe acute abdominal pain
•43% prior chronic mesenteric ischemia symptoms •65% vs 6% thrombus vs. embolus group
•81% Angiography
•Distinction between embolism and thrombosis not always made prior to surgery
•OR •Revascularization (single vessel bypass) •53% bowel resection at first look •50% second look, 50% required additional bowel resection
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•Major complications 79% •Respiratory failure and multiorgan failure
•Mortality 30 Day = 32%
•31% embolism, 32% thrombosis, 80% NOMI
•24 patients died within 90 days (23 in hospital) •Cardiac, short bowel, mesenteric ischemia recurrence
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High index of suspicion – look for risk factors Clinical picture does not reflect severity Time is the major factor , prompt peri-operative planning At surgery, focus on re-vascularization, know options in each scenario Second look!
Summary
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References Fischer et al. Mastery of Surgery ,6th edition Schwartz’s Principles of Surgery, 9th edition Zelenock G et al. Mastery of Vascular and Endovascular Surgery Park W. et al. Contemporary management of acute mesenteric ischemia : Factors associated with Survival Journal of Vascular Surgery 2002
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