Grace Yu, Medical StudentGrace Yu, Medical Student

Surgery Core ClerkshipSurgery Core Clerkship

July 2004July 2004

Case PresentationCase Presentation

CaseCase

79 y/o F h/o Afib presents c 3 month h/o near syncopal 79 y/o F h/o Afib presents c 3 month h/o near syncopal episodes associated c transient confusion and slurred episodes associated c transient confusion and slurred speech admitted to hospital. speech admitted to hospital.

PE nml except for tachycardia 110. EKG Afib c rapid PE nml except for tachycardia 110. EKG Afib c rapid ventricular rate. TTE nml. CT brain showed AVM. ventricular rate. TTE nml. CT brain showed AVM.

Hospital course: successful cardioversion. Not given Hospital course: successful cardioversion. Not given anticoagulation before cardioversion b/c AVM considered anticoagulation before cardioversion b/c AVM considered contraindication. Coronary angiography recommended for contraindication. Coronary angiography recommended for neurosurgery and underwent cardiac catherization.neurosurgery and underwent cardiac catherization.

Sirmon, M. The Invisible Patient. NEJM 334 (14): 908-911. 1996

CaseCase

6 hours after catherization, severe generalized abdominal 6 hours after catherization, severe generalized abdominal pain, nausea, vomiting, and diarrhea. Stool tested pain, nausea, vomiting, and diarrhea. Stool tested positive for occult blood. WBC increased to 21K with L positive for occult blood. WBC increased to 21K with L shift. Abdominal films revealed nml gas distribution in shift. Abdominal films revealed nml gas distribution in the small and large bowels without free air.the small and large bowels without free air.

The pain persisted, and the following day the pt passed The pain persisted, and the following day the pt passed BRBPR. Examination revealed mild abdominal BRBPR. Examination revealed mild abdominal distension, hypoactive bowel sounds, and voluntary distension, hypoactive bowel sounds, and voluntary guarding. She underwent esophagogastroscopy with guarding. She underwent esophagogastroscopy with unremarkable findings, followed by colonoscopy, which unremarkable findings, followed by colonoscopy, which revealed bloody mucus but no evidence of ischemic revealed bloody mucus but no evidence of ischemic colitis. WBC increased to 29K and metabolic acidosis colitis. WBC increased to 29K and metabolic acidosis developed. developed.

Sirmon, M. The Invisible Patient. NEJM 334 (14): 908-911. 1996

CaseCase

Abdominal exploration revealed gangrenous Abdominal exploration revealed gangrenous bowel, extending from ligament of Treitz to bowel, extending from ligament of Treitz to the hepatic flexure of the colon. No further the hepatic flexure of the colon. No further surgery was performed and the incision was surgery was performed and the incision was closed. The pt died 12 hrs later.closed. The pt died 12 hrs later.

Sirmon, M. The Invisible Patient. NEJM 334 (14): 908-911. 1996

Diagnosis?Diagnosis?

Acute Mesenteric Acute Mesenteric IschemicIschemic

Atheroemboli dislogded during cardiac Atheroemboli dislogded during cardiac catherizationcatherization

DefinitionDefinition

Abrupt reduction in blood flow to intestinal Abrupt reduction in blood flow to intestinal circulation of sufficient magnitude to circulation of sufficient magnitude to

compromise metabolic requirements and compromise metabolic requirements and potentially threaten the viability of affected potentially threaten the viability of affected

organs.organs.

EpidemiologyEpidemiology

Incidence as high as 1 in 1,000 pts Incidence as high as 1 in 1,000 pts Expected to increase c aging populationExpected to increase c aging populationDespite growing awareness, morbidity and Despite growing awareness, morbidity and

mortality remain highmortality remain highMortality 59-93%Mortality 59-93%

PathophysiologyPathophysiology 10-30% resting C.O. devoted to intestinal blood flow10-30% resting C.O. devoted to intestinal blood flow Most directed towards mucosa, layer c greatest Most directed towards mucosa, layer c greatest

metabolic demand and highest rate of cell turnovermetabolic demand and highest rate of cell turnover Sudden reduction blood flow -> organ ischemia Sudden reduction blood flow -> organ ischemia

specifically compromising mucosa specifically compromising mucosa Inflm cell infiltrate, loss of capillary integrity c bowel wall Inflm cell infiltrate, loss of capillary integrity c bowel wall

edema -> bacterial translocation, endotoxemia, edema -> bacterial translocation, endotoxemia, exudation of fluid from small bowel.exudation of fluid from small bowel.

Injured mucosa sloughs -> ulceration -> necrosis of Injured mucosa sloughs -> ulceration -> necrosis of muscularis and serosamuscularis and serosa

Septic shock, MSOFSeptic shock, MSOF

Etiology?Etiology?

4 types4 types

1.1. Mesenteric Arterial Embolus Mesenteric Arterial Embolus

2.2. Mesenteric Arterial ThrombosisMesenteric Arterial Thrombosis

3.3. NonOcclusive Mesenteric Ischemia NonOcclusive Mesenteric Ischemia (NOMI)(NOMI)

4.4. Mesenteric Venous Thrombosis (MVT)Mesenteric Venous Thrombosis (MVT)

1. Mesenteric Arterial Embolism1. Mesenteric Arterial Embolism 50% AMI cases50% AMI cases Perferentially lodges SMAPerferentially lodges SMA Causes of EmboliCauses of Emboli

p MI: akinetic or aneurysmal portion LV c thrombusp MI: akinetic or aneurysmal portion LV c thrombus Afib: LA mural thrombusAfib: LA mural thrombus Bacterial endocarditis: septic emboliBacterial endocarditis: septic emboli Intracardiac shunt: paradoxical embolus from LE DVTIntracardiac shunt: paradoxical embolus from LE DVT Atheroemboli dislodging spontaneously from proximal Atheroemboli dislodging spontaneously from proximal

aortaaorta Catheter manipulation during endovascular procedureCatheter manipulation during endovascular procedure Some cases, source embolic occlusion never Some cases, source embolic occlusion never

identifiedidentified

50%

2. Mesenteric Artery Thrombosis2. Mesenteric Artery Thrombosis

Atherosclerotic occlusive lesions tend to occur at Atherosclerotic occlusive lesions tend to occur at origins, or very proximal segments, of the origins, or very proximal segments, of the mesenteric vesselsmesenteric vessels

Stenosis usu progresses over number of years Stenosis usu progresses over number of years and pts remain symptom free if adequate and pts remain symptom free if adequate collateral circulationcollateral circulation

Thrombosis of residual lumen often occurs Thrombosis of residual lumen often occurs during periods of relative hypotension or during periods of relative hypotension or reduced flow (e.g. dehydration)reduced flow (e.g. dehydration)

In some cases, hemorrhage into wall of In some cases, hemorrhage into wall of atherosclerotic plaque leads to complete atherosclerotic plaque leads to complete occlusion of vessel lumen.occlusion of vessel lumen.

2. Mesenteric Artery Thrombosis2. Mesenteric Artery Thrombosis

Chronic AS most common etiologyChronic AS most common etiologyOther entities:Other entities:

Aortic aneurysmAortic aneurysmArterial dissectionArterial dissection Isolated dissection of mesenteric vessel Isolated dissection of mesenteric vessel

spontaneously or result of catheterspontaneously or result of catheterFibromuscular dysplasiaFibromuscular dysplasiaVasculitidies (e.g. Takayasu’s arteritis)Vasculitidies (e.g. Takayasu’s arteritis)Hypercoaguable stateHypercoaguable state

3. Nonocclusive Mesenteric 3. Nonocclusive Mesenteric Ischemia (NOMI)Ischemia (NOMI)

Severe mesenteric vasoconstrictionSevere mesenteric vasoconstrictionCauses: Causes:

shock (septic, cardiogenic, hypovolemic) shock (septic, cardiogenic, hypovolemic) relative dehydration or hypoperfusion = relative dehydration or hypoperfusion =

severe diarrhea, third spacing (burns, severe diarrhea, third spacing (burns, peritonitis)peritonitis)

Alpha adrenergic agonists (phenylephrine, Alpha adrenergic agonists (phenylephrine, NE, Epi)NE, Epi)

Other drugs (ergot alkaloids, diuretics, Other drugs (ergot alkaloids, diuretics, digitalis, cocaine, etc.)digitalis, cocaine, etc.)

4. Mesenteric Venous Thrombosis (MVT)4. Mesenteric Venous Thrombosis (MVT)

Thrombus typically in portal or superior mesenteric venous system -Thrombus typically in portal or superior mesenteric venous system -> intestinal ischemia> intestinal ischemia

Increased hydrostatic pressure leads to luminal fluid sequestration Increased hydrostatic pressure leads to luminal fluid sequestration and bowel wall edemaand bowel wall edema

Ensuing relative hypovolemia and hemoconcentration may Ensuing relative hypovolemia and hemoconcentration may contribute to vasoconstriction -> infarctioncontribute to vasoconstriction -> infarction

Causes:Causes: Hypercoagulable states (e.g. polycythemia vera, OCPs, inherited)Hypercoagulable states (e.g. polycythemia vera, OCPs, inherited) Traumatic injuryTraumatic injury Obstruction venous flow (e.g. portal HTN, abdominal tumors)Obstruction venous flow (e.g. portal HTN, abdominal tumors) Intra-abdominal infxn or inflm (appendicitis, diverticulitis, abscess)Intra-abdominal infxn or inflm (appendicitis, diverticulitis, abscess)

Epi: younger, 30-60 y/o, F>MEpi: younger, 30-60 y/o, F>M Classification: Classification:

acute < 4 weeks vs. chronic > 4 wksacute < 4 weeks vs. chronic > 4 wks primary MVT - no precipitating factor identified (20%) vs.secondary MVT primary MVT - no precipitating factor identified (20%) vs.secondary MVT

- known cause (80%)- known cause (80%)

ETIOLOGYETIOLOGY Incd Incd (%)(%)

AgeAge PresentationPresentation RFRF MortalityMortality

1. Arterial 1. Arterial EmbolismEmbolism

50%50% ElderlyElderly Acute Acute catastrophecatastrophe

ArrhythmiasArrhythmias

Recent MIRecent MI

CHFCHF

RF, endocarditis, RF, endocarditis, CM, ventricular CM, ventricular anuerysms, h/o anuerysms, h/o emblic events, emblic events, recent angiographyrecent angiography

HighHigh

2. Arterial 2. Arterial ThrombosisThrombosis

25%25% ElderlyElderly Insidious Insidious onset, onset, progression progression constant painconstant pain

Systemic AS, Systemic AS, prolonged prolonged hypotension, hypotension, estrogen, estrogen, hypercoagul.hypercoagul.

Very highVery high

3. Non-3. Non-occlusive occlusive mesenteric mesenteric ischemiaischemia

20%20% ElderlyElderly Acute or Acute or subacutesubacute

Shock, Shock, hypotension, hypotension, hypovolemia, hypovolemia, CPB, alpha-CPB, alpha-agonists, burns, agonists, burns, pancreatitispancreatitis

HighestHighest

4. Mesenteric 4. Mesenteric venous venous thrombosisthrombosis

5% 5% Young Young erer

SubacuteSubacute Hypercoag, portal Hypercoag, portal HTN, Infxn/inflm, HTN, Infxn/inflm, prior surgery, prior surgery, traumatrauma

LowestLowest

History: History: Classic Triad SMA embolismClassic Triad SMA embolism

Acute onset abdominal pain

Gut emptying(Vomiting, diarrhea)

Hx Afib, heart dx

HistoryHistory

1&2. AMI secondary to embolus or thrombus1&2. AMI secondary to embolus or thrombus77thth-8-8thth decades decadesCAD, PVD, cardiac dysrhythmiasCAD, PVD, cardiac dysrhythmiasAbdominal Pain:Abdominal Pain:

Acute onset with rapid progression over few hours Acute onset with rapid progression over few hours most typical of embolic occlusionmost typical of embolic occlusion

May be colicky initially -> sustained as bowel May be colicky initially -> sustained as bowel viability compromisedviability compromised

Diffuse or localized to any quadrant of abdomen Diffuse or localized to any quadrant of abdomen Vomiting, diarrheaVomiting, diarrheaOccult blood stool -> frankly bloody diarrheaOccult blood stool -> frankly bloody diarrhea

HistoryHistory Pts c thrombosed vessel c collaterals may have Pts c thrombosed vessel c collaterals may have

more insidious onset c prodrome of anorexia, more insidious onset c prodrome of anorexia, malaise, vague sxms -> evolve into frank malaise, vague sxms -> evolve into frank distress over a few dysdistress over a few dys

Weight loss, recent illness, changes in eating Weight loss, recent illness, changes in eating habits, postprandial discomfort leading to food habits, postprandial discomfort leading to food aversion (abdominal angina) helps to aversion (abdominal angina) helps to differentiate thrombotic from embolic etiologies, differentiate thrombotic from embolic etiologies, although acute arterial thrombosis may have no although acute arterial thrombosis may have no sxms prior to acute event. sxms prior to acute event.

Precipitating event may be sudden drop in C.O., Precipitating event may be sudden drop in C.O., MI, CHF, ruptured plaque, dehydrationMI, CHF, ruptured plaque, dehydration

HistoryHistory

3. Nonocclusive mesenteric ischemia 3. Nonocclusive mesenteric ischemia Especially difficult b/c many pts already critically Especially difficult b/c many pts already critically ill in ICU, obtunded, Hx unattainableill in ICU, obtunded, Hx unattainable Rare, potentially life-threatening in cardiac surgery ptsRare, potentially life-threatening in cardiac surgery pts

Incidence 0.06-0.36%Incidence 0.06-0.36% RF: emergent procedures, prolonged pump time, IABP, RF: emergent procedures, prolonged pump time, IABP,

advanced age, failed coronary angioplastyadvanced age, failed coronary angioplasty Occurs dys after initial procedure with mean abdominal Occurs dys after initial procedure with mean abdominal

exploration time 4-9 dys p cardiac surgeryexploration time 4-9 dys p cardiac surgery Delay may be secondary vent support/sedation resulting in Delay may be secondary vent support/sedation resulting in

less accurate PEless accurate PE

HistoryHistory

4. Mesenteric Vein Thrombosis4. Mesenteric Vein Thrombosis RF: hypercoagulable state (e.g. inherited, OCP, RF: hypercoagulable state (e.g. inherited, OCP,

DVT, cancer, tumor, portocaval surgery)DVT, cancer, tumor, portocaval surgery) Insidious onset over 7-14 dysInsidious onset over 7-14 dys

>48 hrs in 75% pts>48 hrs in 75% pts w/in 24 hrs only 9% ptsw/in 24 hrs only 9% pts

Poorly localized pain associated c:Poorly localized pain associated c: Abdominal distensionAbdominal distension AnorexiaAnorexia N/VN/V DiarrheaDiarrhea

PhysicalPhysical Sine qua non = severe abdominal pain out of proportion Sine qua non = severe abdominal pain out of proportion

to physical exam findings early in course of illnessto physical exam findings early in course of illness Dehydration signs: dry mucus membranes, decreased Dehydration signs: dry mucus membranes, decreased

skin turgor, flat neck veinsskin turgor, flat neck veins Hypoperfusion seen in NOMI: cool extremities c faint or Hypoperfusion seen in NOMI: cool extremities c faint or

absent pulses, mottled skinabsent pulses, mottled skin CV: arrhythmias (Afib) for embolic, CHFCV: arrhythmias (Afib) for embolic, CHF GI: abdominal bruits, scarsGI: abdominal bruits, scars

Early: abdomen soft, NT, NABSEarly: abdomen soft, NT, NABS Ischemia progresses: guarding, hypoactive bowel sounds, Ischemia progresses: guarding, hypoactive bowel sounds,

absent bowel sounds, distension, ascites, Hemoccult positive absent bowel sounds, distension, ascites, Hemoccult positive stools, bloody diarrheastools, bloody diarrhea

Later: progressive guarding, peritonitis as full-thickness intestinal Later: progressive guarding, peritonitis as full-thickness intestinal ischemia, necrosis, perforation. Tenderness severe and may ischemia, necrosis, perforation. Tenderness severe and may localize to infarcted bowel segment. Tachycardia, hypotension, localize to infarcted bowel segment. Tachycardia, hypotension, tachypnea, altered mental statustachypnea, altered mental status

LabsLabs

CBCDCBCDChem 10Chem 10

CoagsCoagsLFTsLFTs

AmylaseAmylaseABGABG

LactateLactate

Advanced intestinal ischemia -> leukocytosis; metabolic acidosis, Advanced intestinal ischemia -> leukocytosis; metabolic acidosis, elevated lactate; elevated amylase level, LDH, CPK, AST but non-elevated lactate; elevated amylase level, LDH, CPK, AST but non-specificspecific

Hemoconcentration c/w dehydration ubiquitous in NOMIHemoconcentration c/w dehydration ubiquitous in NOMI However, absence should not dissuade from suspecting mesenteric However, absence should not dissuade from suspecting mesenteric

ischemia. ischemia. No clear markers to establish or exclude AMI and labs are generally No clear markers to establish or exclude AMI and labs are generally

not helpful.not helpful.

StudiesStudies Abdominal XRaysAbdominal XRays

r/o other causes: perforated viscus, small or large bowel r/o other causes: perforated viscus, small or large bowel obstructionobstruction

Often nml in AMI and positive findings usu late and non-specificOften nml in AMI and positive findings usu late and non-specific ““thumbprinting,” bowel wall thickeningthumbprinting,” bowel wall thickening Pneumatosis intestinalis = bowel infarctionPneumatosis intestinalis = bowel infarction

rarely seen (5%) rarely seen (5%) Also associated c other benign findings (e.g. COPD, IBD, Also associated c other benign findings (e.g. COPD, IBD,

mechanical ventilation)mechanical ventilation) Air in portal venous circulation, bilary tree, free peritoneal airAir in portal venous circulation, bilary tree, free peritoneal air

Late findings c/w bowel necrosisLate findings c/w bowel necrosis Paucity of bowel gas and adynamic ileusPaucity of bowel gas and adynamic ileus

Most frequent finding in MVTMost frequent finding in MVT

Pneumatosis IntestinalisPneumatosis Intestinalis

StudiesStudies CT, CTACT, CTA

May be nml or nondiagnosticMay be nml or nondiagnostic Series of 39 pts, 64% sensitive, 92% specific c at Series of 39 pts, 64% sensitive, 92% specific c at

least one finding:least one finding: Arterial or venous thrombosisArterial or venous thrombosis Intramural gasIntramural gas Portal venous gasPortal venous gas Thickened BWThickened BW Liver or spleen infarctsLiver or spleen infarcts

Diagnostic choice in MVT, sensitivity 90%Diagnostic choice in MVT, sensitivity 90% Superior mesenteric or portal vein enlarged c central areas Superior mesenteric or portal vein enlarged c central areas

of attenuation suggestive of thrombus.of attenuation suggestive of thrombus. BW thickening and presence of ascites also suggestiveBW thickening and presence of ascites also suggestive

34 y/o woman c nonspecific abdominal pain c protein C deficiency

Other studiesOther studies MRI/MRA – similar findings as CT scan, major drawback MRI/MRA – similar findings as CT scan, major drawback

expense and timeexpense and time Duplex US exam of mesenteric circulationDuplex US exam of mesenteric circulation

Useful in chronic mesenteric ischemiaUseful in chronic mesenteric ischemia Distended bowel loops limits role in AMIDistended bowel loops limits role in AMI Does not exclude embolic phenomenon, but absence flow and Does not exclude embolic phenomenon, but absence flow and

ascites highly suggestive MVTascites highly suggestive MVT ECHO - Confirm source of emboliECHO - Confirm source of emboli EKG – MI or AfibEKG – MI or Afib Endoscopy - dx ischemic colitis but does not visulaize Endoscopy - dx ischemic colitis but does not visulaize

much of small bowel which is frequently involvedmuch of small bowel which is frequently involved Barium studiesBarium studies

Contraindicated as increased intraluminal pressure -> perforation Contraindicated as increased intraluminal pressure -> perforation and residual barium may obscure crucial angiographic findingsand residual barium may obscure crucial angiographic findings

Arteriography = Gold StandardArteriography = Gold Standard

ArteriographyArteriography

Establishes dx, differentiates between thrombotic, Establishes dx, differentiates between thrombotic, embolic, and non-occlusive etiologies, allow early embolic, and non-occlusive etiologies, allow early nonoperative therapeutic intervention, allows surgeon nonoperative therapeutic intervention, allows surgeon select appropriate operative approachselect appropriate operative approach

Biplanar (AP and lateral) views of aorta and branchesBiplanar (AP and lateral) views of aorta and branches

Arteriography Findings Based on Arteriography Findings Based on EtiologyEtiology

Acute Thrombotic occlusionAcute Thrombotic occlusion Origin of SMA or celiac axis c opacification of short segment of Origin of SMA or celiac axis c opacification of short segment of

these vessels; may see collateralsthese vessels; may see collaterals Diffuse atheromatous disease in abdominal aortaDiffuse atheromatous disease in abdominal aorta

Acute Embolic occlusionAcute Embolic occlusion Inverted meniscus sign several cm distal to origin of SMA usu at Inverted meniscus sign several cm distal to origin of SMA usu at

origin of middle colic arteryorigin of middle colic artery SMA, other mesenteric vessels, abdominal aorta relatively SMA, other mesenteric vessels, abdominal aorta relatively

undiseasedundiseased Poor collaterals, multiple emboliPoor collaterals, multiple emboli

Lateral arteriogram: embolus in SMA several cm from origin

Arteriography Findings Based on Arteriography Findings Based on EtiologyEtiology

MVTMVT Not as helpful esp segmental venous thrombosisNot as helpful esp segmental venous thrombosis Most importantly, can exclude embolus, thrombus, Most importantly, can exclude embolus, thrombus,

NOMINOMI NOMINOMI

Mesenteric vessels may be patent w or w/o evidence Mesenteric vessels may be patent w or w/o evidence of chronic diseaseof chronic disease

Intermittent areas of narrowing and dilatation (“string Intermittent areas of narrowing and dilatation (“string of sausages”) c/w arterial vasoconstriction of spasmof sausages”) c/w arterial vasoconstriction of spasm

Dx test: direct infusion papaverine (60mg) into SMA Dx test: direct infusion papaverine (60mg) into SMA can reverse vasoconstricion and confirms diagnosis -can reverse vasoconstricion and confirms diagnosis -> can leave catheter in place for continuous > can leave catheter in place for continuous therapeutic infusiontherapeutic infusion

NOMI intermittent spasm and dilatation of vessels “string of sausages”

Medical RxMedical Rx

Substantial protein-rich fluid losses in gut Substantial protein-rich fluid losses in gut Supportive RxSupportive Rx Aggressive fluid resuscitationAggressive fluid resuscitation

Guided by art line, Foley, central line, Swan-GanzGuided by art line, Foley, central line, Swan-Ganz Volume resuscitation to allow weaning of vasopressorsVolume resuscitation to allow weaning of vasopressors

NE and Phenylephrine particularly deleteriousNE and Phenylephrine particularly deleterious Dopamine more appropriate as may cause less severe mesenteric Dopamine more appropriate as may cause less severe mesenteric

vasoconstriction vasoconstriction Digitalis well-recognized vasoconstrictor of SMA smooth muscle and d/c’ed if Digitalis well-recognized vasoconstrictor of SMA smooth muscle and d/c’ed if

possiblepossible NPONPO NG = decompress fluid-filled and distended intestinal tract to NG = decompress fluid-filled and distended intestinal tract to

promote perfusion, decrease risk perforation, minimize aspiration promote perfusion, decrease risk perforation, minimize aspiration riskrisk

Broad-spectrum ABx including anaerobes given bacterial Broad-spectrum ABx including anaerobes given bacterial translocation through compromised intestinal barrier and translocation through compromised intestinal barrier and documented hi incidence of positive blood culturesdocumented hi incidence of positive blood cultures

Respiratory support (100%, intubation if necessary), pain controlRespiratory support (100%, intubation if necessary), pain control

Medical RxMedical Rx Anticoagulation dependent on etiology of AMIAnticoagulation dependent on etiology of AMI MVTMVT

Heparin decreases recurrence thrombosis 26->14% and Heparin decreases recurrence thrombosis 26->14% and mortality 59->22%mortality 59->22%

Long-term anticoagulation c warfarin, esp if underlying Long-term anticoagulation c warfarin, esp if underlying hypercoagulable statehypercoagulable state

Acute arterial thrombosis or embolus anticoagulation Acute arterial thrombosis or embolus anticoagulation problematicproblematic Early heparin administration can prevent thrombus extension, Early heparin administration can prevent thrombus extension,

benefit must be weighed against risk of significant GI bleed in benefit must be weighed against risk of significant GI bleed in bowel ischemiabowel ischemia

In most cases, urgent surgical exploration required and In most cases, urgent surgical exploration required and anticoagulation should be held pre-operativelyanticoagulation should be held pre-operatively

Post-op: anticoagulation recommended in those c embolic Post-op: anticoagulation recommended in those c embolic occlusion, but may not be necessary after revascularization for occlusion, but may not be necessary after revascularization for thrombosisthrombosis

Interventional RadiologyInterventional Radiology Unlike other causes of AMI, primary treatment of NOMI Unlike other causes of AMI, primary treatment of NOMI

is pharmacologicis pharmacologic Catheter directed administration of number of Catheter directed administration of number of

vasodilating agents including papaverine, tolazoline, vasodilating agents including papaverine, tolazoline, glucagon, NTG, NTP, prostaglandin E, glucagon, NTG, NTP, prostaglandin E, phenoxybenzamine, isoproterenolphenoxybenzamine, isoproterenol

Most clinical experience c papaverineMost clinical experience c papaverine 60mg c repeat contrast injection demonstrates reversal of 60mg c repeat contrast injection demonstrates reversal of

vasoconstrictionvasoconstriction Catheter left in place c continuous infusion @ 30-60mg/hrCatheter left in place c continuous infusion @ 30-60mg/hr Acccompanied by heparin to prevent propagation of thrombus Acccompanied by heparin to prevent propagation of thrombus

during low-flow state or formation at catheter siteduring low-flow state or formation at catheter site Failure to improve or deterioration mandates immediate Failure to improve or deterioration mandates immediate

surgical explorationsurgical exploration Catheter may be left in place post-operatively to maximize Catheter may be left in place post-operatively to maximize

perfusion of marginally viable bowel after resection of frankly perfusion of marginally viable bowel after resection of frankly gangrenous segmentsgangrenous segments

Interventional RadiologyInterventional Radiology Catheter directed thrombolysis anecdoctal Catheter directed thrombolysis anecdoctal

Risk of intestinal hemorrhageRisk of intestinal hemorrhage Elderly pt c severe medical co-morbidities and clinical Elderly pt c severe medical co-morbidities and clinical

presentation of early ischemia, this Rx may avoid presentation of early ischemia, this Rx may avoid potentially morbid surgery, esp if bowel viability can potentially morbid surgery, esp if bowel viability can be confirmed through laparascopybe confirmed through laparascopy

Percutaneous transluminal angioplastyPercutaneous transluminal angioplasty After successful lysis thrombus, can treat underlying After successful lysis thrombus, can treat underlying

chronic occlusive disease c PTAchronic occlusive disease c PTA Matsumoto et.al. documented technical success Matsumoto et.al. documented technical success

102/126 (86%) underwsent PTA of chronic visceral 102/126 (86%) underwsent PTA of chronic visceral arterial lesionsarterial lesions

Major complicatons 6%Major complicatons 6%

Surgical RxSurgical Rx

Operative delay is the Operative delay is the most important most important determinant of adverse determinant of adverse outcomeoutcome

Goal to confirm diagnosis Goal to confirm diagnosis of mesenteric ischemia, of mesenteric ischemia, assess bowel viability, assess bowel viability, perform revascularization perform revascularization if possible, and resect if possible, and resect nonviable bowelnonviable bowel

SurgerySurgery OR: equipped Wood’s lamp, fluorescein, continuous wave Doppler OR: equipped Wood’s lamp, fluorescein, continuous wave Doppler

U/SU/S Pt supine c wide field extending nipples to knees prepped and Pt supine c wide field extending nipples to knees prepped and

draped to allow harvesting GSV if necessarydraped to allow harvesting GSV if necessary Abdomen entered long midline incision and bowel carefully Abdomen entered long midline incision and bowel carefully

examined from stomach to rectosigmoid. A definite determination of examined from stomach to rectosigmoid. A definite determination of intestinal viability should not be made until revascularization intestinal viability should not be made until revascularization performedperformed

Palpation of pulsations or Doppler signals in peripheral of mesentery Palpation of pulsations or Doppler signals in peripheral of mesentery may represent collaterals -> this finding does not r/o SMA occlusionmay represent collaterals -> this finding does not r/o SMA occlusion

SMA isolated at base of mesentery at it exits underneath pancreas SMA isolated at base of mesentery at it exits underneath pancreas and exposed several cm distallyand exposed several cm distally Strong pulsation at base but not palpable distally highly suggestive Strong pulsation at base but not palpable distally highly suggestive

embolus, whereas absent pulsation in proximal SMA suggestive embolus, whereas absent pulsation in proximal SMA suggestive thrombusthrombus

Use Doppler if no pulses detectableUse Doppler if no pulses detectable Examine celiac axis, IMA, and main branchesExamine celiac axis, IMA, and main branches

SurgerySurgery Inspection of bowel can uncover etiologyInspection of bowel can uncover etiology

Acute SMA thrombosis: typically compromises Acute SMA thrombosis: typically compromises viability R colon and entire small intestineviability R colon and entire small intestine

Embolic occlusion: lodges more distally and proximal Embolic occlusion: lodges more distally and proximal jejunum may be spared, and more patchy jejunum may be spared, and more patchy involvement in pts c multiple distal emboliinvolvement in pts c multiple distal emboli

MVT: marked edema of intestine and mesentery, MVT: marked edema of intestine and mesentery, cyanotic discoloration bowel, palpable mesenteric cyanotic discoloration bowel, palpable mesenteric arterial pulsationsarterial pulsations

NOMI: peripheral arterial pulsations c distal attn noted NOMI: peripheral arterial pulsations c distal attn noted in absence of apparent thrombosis -> minimize in absence of apparent thrombosis -> minimize arterial manipulation to avoid further vasoconstriction arterial manipulation to avoid further vasoconstriction -> urgent transfer to angiography for vasodilatory Rx-> urgent transfer to angiography for vasodilatory Rx

SurgerySurgeryRevascularization for EmbolusRevascularization for Embolus SMA controlled distal to origin of middle colic artery and SMA controlled distal to origin of middle colic artery and

proximal to jejunal arteries and arteriotomy performedproximal to jejunal arteries and arteriotomy performed Transverse arteriotomy or if any doubt, longitudinal to Transverse arteriotomy or if any doubt, longitudinal to

serve as distal anastomosis of bypass graftserve as distal anastomosis of bypass graft Thrombombolectomy cathether can retrieve embolus Thrombombolectomy cathether can retrieve embolus

and thrombotic materialand thrombotic material Also may be possible to “milk” clot manually from distal Also may be possible to “milk” clot manually from distal

vasculaturevasculature Infuse heparin distally and for smaller thromboemboli Infuse heparin distally and for smaller thromboemboli

thrombolytics may be usedthrombolytics may be used Infuse vasodilator (e.g. papaverine) into distal vessel Infuse vasodilator (e.g. papaverine) into distal vessel

before closingbefore closing Primary closure or patch angioplastyPrimary closure or patch angioplasty

SurgerySurgery

Revascularization for ThrombusRevascularization for ThrombusThromboendarterectomyThromboendarterectomyBypass graft - many options for:Bypass graft - many options for:

conduit used (GSV, synthetic Dacron or conduit used (GSV, synthetic Dacron or polytetrafluoroethylene)polytetrafluoroethylene)

inflow used (infrarenal or supraceliac aorta)inflow used (infrarenal or supraceliac aorta)extent of revascularization extent of revascularization

SurgerySurgery

Mesenteric Vein ThrombosisMesenteric Vein Thrombosis Primary Rx anticoagulationPrimary Rx anticoagulation Thromboembolectomy catheter used to extract Thromboembolectomy catheter used to extract

clotclot Peripheral veins “milked” to extract as much Peripheral veins “milked” to extract as much

thrombus as possiblethrombus as possible When thrombotic process involves more distal When thrombotic process involves more distal

small venous channels, bowel resection may be small venous channels, bowel resection may be only option as common for MVT to extend well only option as common for MVT to extend well beyond what appears to be compromised bowel beyond what appears to be compromised bowel -> wide margin for resection and low threshold -> wide margin for resection and low threshold for second-look operationfor second-look operation

Surgical ResectionSurgical Resection

Bowel returned to abdominal cavity and Bowel returned to abdominal cavity and anesthesiologist maximize hemodynamic status anesthesiologist maximize hemodynamic status for 30-45 min before making definitive for 30-45 min before making definitive assessment of intestinal viability and necessity assessment of intestinal viability and necessity for bowel resectionfor bowel resection

Clinical signs (absence peristalsis, bowel wall Clinical signs (absence peristalsis, bowel wall edema, discoloration of bowel and mesentery, edema, discoloration of bowel and mesentery, mucosal hemorrhage, absence of bleeding from mucosal hemorrhage, absence of bleeding from cut edges) are imprecise markers and may lead cut edges) are imprecise markers and may lead to excessive resection.to excessive resection.

Surgical ResectionSurgical Resection

Objective modalities:Objective modalities: Continuous wave Doppler ultrasoundContinuous wave Doppler ultrasound Fluorescein IV with Wood’s lampFluorescein IV with Wood’s lamp Johns Hopkins prospective study: fluoroscein 100% Johns Hopkins prospective study: fluoroscein 100%

accurate, clinical judgment 89%, and Doppler 84% accurate, clinical judgment 89%, and Doppler 84% accurate in predicting bowel viabilityaccurate in predicting bowel viability

All nonviable bowel resected or long segments All nonviable bowel resected or long segments marginal bowel left in situ with continuity marginal bowel left in situ with continuity reestablished during second-look procedure 18-reestablished during second-look procedure 18-24 hrs later24 hrs later

Postoperative CarePostoperative Care

Postoperative CarePostoperative Care Primary focus: vigorous cardiopulmonary resuscitation, Primary focus: vigorous cardiopulmonary resuscitation,

esp in NOMI and recognized mesenteric capillary leak esp in NOMI and recognized mesenteric capillary leak syndromesyndrome Aggressive blood and electrolyte rich fluidsAggressive blood and electrolyte rich fluids

May require 10-20L crystalloid in first 24-48 hrs May require 10-20L crystalloid in first 24-48 hrs Correction arrhythmiasCorrection arrhythmias VasopressorsVasopressors

Dopamine 3-8mcg/kg/min, Epi 0.05-0.10 ug/kg/min.Dopamine 3-8mcg/kg/min, Epi 0.05-0.10 ug/kg/min. Pure alpha agonists should be avoidedPure alpha agonists should be avoided

Limit reperfusion injury with free oxygen scavengers: ACEI, Limit reperfusion injury with free oxygen scavengers: ACEI, AllopurinolAllopurinol

Correct metabolic acidosisCorrect metabolic acidosis Sepsis common = Broad spectrum ABx with anaerobic Sepsis common = Broad spectrum ABx with anaerobic

coverage for at least 5 dyscoverage for at least 5 dys Prolonged NG decompressionProlonged NG decompression Early institution of parenteral nutritionEarly institution of parenteral nutrition

Postoperative Care: Postoperative Care: AnticoagulationAnticoagulation

MVT = Anticoagulation mainstay of therapyMVT = Anticoagulation mainstay of therapy Heparin at time of dx and continued postoperativelyHeparin at time of dx and continued postoperatively Duration of long-term warfarin depends on underlying Duration of long-term warfarin depends on underlying

causecause Embolus = administer heparinEmbolus = administer heparin NOMI = anticoagulation generally not necessaryNOMI = anticoagulation generally not necessary Most critically ill pts c AMI after Most critically ill pts c AMI after

revascularization, hypocoagulable state revascularization, hypocoagulable state secondary liver dysfxn -> replenish coagulation secondary liver dysfxn -> replenish coagulation factors to Rx GI bleedingfactors to Rx GI bleeding

PrognosisPrognosis

Overall mortality 60%Overall mortality 60%

SummarySummary Think of mesenteric ischemia in DDxThink of mesenteric ischemia in DDx HxHx

Classic triad in SMA embolus: acute onset, Gi emptying Classic triad in SMA embolus: acute onset, Gi emptying (vomiting, diarrhea), and h/o cardiac dz(vomiting, diarrhea), and h/o cardiac dz

Abdominal distension, hemmoccult positive stool, bloody Abdominal distension, hemmoccult positive stool, bloody diarrhea, h/o abdominal anginadiarrhea, h/o abdominal angina

Co-morbidities: CV disease, arryhthmias, hypotension, Co-morbidities: CV disease, arryhthmias, hypotension, hypercoagulablehypercoagulable

PE - abdominal pain out of proportion to physical exam PE - abdominal pain out of proportion to physical exam findings early in illnessfindings early in illness

Labs non-specific Labs non-specific Studies: CT, Angiogram gold standardStudies: CT, Angiogram gold standard Rx: Medical, IR, SurgeryRx: Medical, IR, Surgery Mortality remains highMortality remains high Early diagnosis dramatically increases survivalEarly diagnosis dramatically increases survival

ReferencesReferences Chang, et. al. Mesenteric Ischemia: Acute and Chronic. Annals of Chang, et. al. Mesenteric Ischemia: Acute and Chronic. Annals of

Vascular Surgery. 17: 323-329. 2003Vascular Surgery. 17: 323-329. 2003 Dang, C. Acute Mesenteric Ischemia. Dang, C. Acute Mesenteric Ischemia.

www.emedicine.com/med/topic2627.htmwww.emedicine.com/med/topic2627.htm Lee. R. et.al. CT in Acute Mesenteric Ischemia. Clinical Radiology. Lee. R. et.al. CT in Acute Mesenteric Ischemia. Clinical Radiology.

58: 279-287. 2003. 58: 279-287. 2003. Oldenberg, A. et.al. Acute Mesenteric Ischemia. Arch Intern Med. Oldenberg, A. et.al. Acute Mesenteric Ischemia. Arch Intern Med.

164: 1054-1062. 2004.164: 1054-1062. 2004. Sabiston textbook of surgery. pg. 1398-1404. W. B. Saunders Sabiston textbook of surgery. pg. 1398-1404. W. B. Saunders

Company. 2001Company. 2001 Sirmon, M. The Invisible Patient. NEJM 334 (14): 908-911. 1996. surged.utmem.edu/residents/ lecture/slides/MESENTERICsurged.utmem.edu/residents/ lecture/slides/MESENTERIC

%20ISCHEMIA.htm %20ISCHEMIA.htm Tendler, et.al. Acute Mesenteric Ischemia. Tendler, et.al. Acute Mesenteric Ischemia. www.uptodate.comwww.uptodate.com

AddendumAddendum

Results: AcuteResults: Acute

Acute Arterial Thrombosis and EmbolismAcute Arterial Thrombosis and Embolism Survival superior in embolic vs. thrombotic arterial Survival superior in embolic vs. thrombotic arterial

occlusionocclusion Embolic: survival 50-77%Embolic: survival 50-77% Thrombotic: survival: 80-96%Thrombotic: survival: 80-96%

Mortality increases c extent of bowel ischemia and Mortality increases c extent of bowel ischemia and infarctioninfarction Excessive mortality with leukocytosis, peritonitis, resection > Excessive mortality with leukocytosis, peritonitis, resection >

1.5m intestine1.5m intestine Mesenteric angiography can define etiologyMesenteric angiography can define etiology Evidence intra-arterial vasodilator therapy improves Evidence intra-arterial vasodilator therapy improves

survival: 80% mortality -> 45% mortalitysurvival: 80% mortality -> 45% mortality

Results: AcuteResults: Acute

NOMINOMI Mortality 70-90%Mortality 70-90% Decline in incidence b/c greater awareness by ICU Decline in incidence b/c greater awareness by ICU

physicians and more liberal administration of intra-physicians and more liberal administration of intra-arterial vasodilatorarterial vasodilator

Intra-arterial papaverine reduced mortality to 50-55%Intra-arterial papaverine reduced mortality to 50-55%

Mesenteric Vein ThrombosisMesenteric Vein Thrombosis Lowest risk mortality: 11-38%Lowest risk mortality: 11-38%

Younger, healthier populationYounger, healthier population Recognition predisposing factors, indolent coruse, and CT Recognition predisposing factors, indolent coruse, and CT

accuracy in diagnosis b/f bowel infarction occursaccuracy in diagnosis b/f bowel infarction occurs Shorter segments bowel infarctedShorter segments bowel infarcted

Results: Long-termResults: Long-term Less studied but relatively favorable prognosisLess studied but relatively favorable prognosis 2 year survival rate: 70%2 year survival rate: 70% 5 year survival rate: 50%5 year survival rate: 50% Mortality highest during 1Mortality highest during 1stst yr yr Common cause of long-term mortality CVCommon cause of long-term mortality CV Recurrent bowel ischemia infrequent b/c aggressive Recurrent bowel ischemia infrequent b/c aggressive

long-term anticoagulationlong-term anticoagulation QOLQOL

38% wt loss38% wt loss 19% reduced appetite19% reduced appetite Bowel resection, 20% short gut syndrome and none required Bowel resection, 20% short gut syndrome and none required

TPNTPN