Unfinished Rosen Notes – Chapter 90 – Disorders Of The Small Intestine

Front 1

- 4 distinct causes of acute mesenteric ischemia:

Back 1

embolic

thrombotic

low flow

venous thrombosis

Front 2

Mesenteric Arterial embolism

epi

location

rf

Back 2

MC, 50%)
§ Mean age >70yrs
§ Usually SMA (usually from cardiac source)
§ RF: CAD, valvular dz, arrhythmias (esp AF)

Front 3

Mesenteric Arterial thrombosis

location

ss

rf

Back 3

(15%)
§ Usually at SMA from atherosclerosis
§ Often preceeding Hx of “abdominal angina” (abdo pain post-prandial)
§ RF: older age, diffuse atherosclerosis and HTN

Front 4

Mesenteric Venous Thrombosis

epi

a/c

Back 4

(15%)
§ Young population, :. lower MR (20-50%)
§ Rarely a primary Dx; often occurs in conjunction with a underlying medical condition (i.e. hypercoagulable state, inflammatory processes within the abdomen, local trauma)
§ Up to 60% have Hx of DVT

Front 5

Non-obstructive / low flow state (20%)

Back 5

§ Mesenteric vaso-constriction usually from low-flow states or from vasopressors

Front 6

- blood supply to abdominal organs:

Back 6

o celiac trunk – esophagus, stomach, proximal duodenum, liver, gallbladder, pancreas, spleen

o superior mesenteric artery (SMA) – distal duodenum, jejunum, ileum, colon to splenic flexure

o inferior mesenteric artery (IMA) – descending colon, sigmoid colon, rectum

o much overlap and collateral blood flow between areas

Front 7

pathophysi mesenteric ischemia

Back 7

visceral mucosa very sensitive to ¯ perfusion, leads to ischemia with typical cascade of inflammatory cytokines, endothelial damage, necrosis, vascular permeability leading to contamination of peritoneum/systemic circulation
- reperfusion injury commonly seen

Front 8

Factors Associated with Mesenteric Arterial Embolism

Back 8

Coronary artery disease

-Post–myocardial infarction mural thrombi

-Congestive heart failure

Valvular heart disease

- Rheumatic mitral valve disease

- Nonbacterial endocarditis

Arrhythmias

Chronic atrial fibrillation

Aortic aneurysms or dissections

Coronary angiography

Front 9

Factors Associated with Mesenteric Venous Thrombosis

Back 9

Factors Associated with Mesenteric Venous Thrombosis

Hypercoagulable states

-Polycythemia vera

-Sickle cell disease

-Antithrombin III deficiency

- Protein C or S deficiency

-Malignancy

-Myeloproliferative disorders

-Estrogen therapy/oral contraceptive pill

-Pregnancy

Inflammatory conditions

Pancreatitis

Diverticulitis

Appendicitis

Cholangitis

Trauma

Operative venous injury

Postsplenectomy

Blunt or abdominal trauma

Miscellaneous

Congestive heart failure

Renal failure

Decompression sickness

Portal hypertension

Front 10

Factors Associated with Nonocclusive Mesenteric Ischemia

Back 10

Cardiovascular disease leading to low-flow states

Congestive heart failure

Arrhythmias

Cardiogenic shock

Post-cardiopulmonary bypass

Preceding hypotensive episode

Septic shock

Drug-induced splanchnic vasoconstriction

Digoxin

Vasopressors

Ergot alkaloid poisoning

Cocaine abuse

Front 11

SS mesenteric ischemia

Back 11

s/s – sudden onset abdominal pain lasting >2h in patient with appropriate risk factors; n/v, frequent bowel movements; pain out of proportion to physical findings

Front 12

DX mesenteric ischemia

Back 12

Labs – VBG/ABG for unexplained acidosis,
§ lactate - sensitivity 100% for infracted bowel, specificity 42 – 87%

§ D-dimer may be useful to exclude mesenteric artery occlusion

o AXR – may show free air, pneumatosis (late), gas within portal venous system (preterminal)

o CT – shows edema of bowel wall, may show evidence of mesenteric venous thrombus
o angiography – gold standard; dx and tx as well as sx planning; contraindicated in shock and vasopressor use