DMS 220A - Mesenteric Arteries Vocabulary

Vocabulary practice flashcards for mesenteric arteries, Doppler physiology, velocity thresholds, MALS, and mesenteric ischemia.

Demand-Driven Vascular Bed

A vascular system, such as the mesenteric circulation, whose flow demand changes significantly based on organ activity, shifting between low perfusion at rest and high flow after meals.

Celiac Artery (CA)

The first major branch arising from the anterior abdominal aorta $1\text{ to }2\,\text{cm}$ below the diaphragm, which branches into the common hepatic, splenic, and left gastric arteries.

Superior Mesenteric Artery (SMA)

The second anterior branch of the abdominal aorta, arising $1\text{ to }2\,\text{cm}$ below the celiac artery, which supplies the gastrointestinal tract from the duodenum to the splenic flexure.

Inferior Mesenteric Artery (IMA)

An anterior branch arising from the distal abdominal aorta roughly $4\,\text{cm}$ above the aortic bifurcation, supplying the distal transverse colon, descending colon, and sigmoid colon.

Mesenteric Duplex Examination

A diagnostic vascular ultrasound protocol where the same visceral vessel is interrogated fasting and again post-prandially to evaluate functional changes in blood flow.

Seagull Sign

A transverse sonographic finding formed by the celiac trunk bifurcation, where the celiac trunk represents the body and the common hepatic and splenic arteries form the wings.

Common Hepatic Artery

A branch of the celiac trunk heading toward the patient's right to supply the liver, gallbladder, and duodenum, forming the right wing of the seagull sign.

Splenic Artery

A branch of the celiac trunk heading toward the patient's left to supply the spleen and pancreatic tail, forming the left wing of the seagull sign and typically following a tortuous course.

Left Gastric Artery

A branch of the celiac artery that supplies the stomach; it is typically too small to be visualized sonographically.

SMA Sagittal Course

The course of the superior mesenteric artery after arising from the aorta, turning caudally to run parallel and anterior to the aorta for several centimeters.

Splenic Vein (Transverse SMA Relationship)

The vascular structure located directly anterior to the superior mesenteric artery in transverse sonographic imaging.

Left Renal Vein (Transverse SMA Relationship)

The vascular structure located posterior to the SMA, coursing horizontally in the space between the SMA and the aorta.

Pancreas (Transverse SMA Relationship)

The organ whose body lies directly anterior to the superior mesenteric artery in transverse imaging.

Anatomic SMA Sandwich

The transverse structural sequence comprising the splenic vein in front, SMA in the middle, left renal vein behind the SMA, and aorta behind the left renal vein.

IMA Sonographic Identification Technique

Locating the aortic bifurcation in transverse and walking the transducer $1\text{ to }3\,\text{cm}$ proximally along the anterior aortic wall.

IMA Duplex Limitation

Due to its small caliber, significant stenosis in the IMA can be completely missed on duplex ultrasound, requiring CT angiography when clinical suspicion is high.

Mesenteric Duplex Fasting Requirement

Patient preparation requiring fasting for $6\text{ to }8\,\text{hours}$ to reduce bowel gas and establish a baseline high-resistance pre-prandial flow state.

Mesenteric Duplex Patient Positioning

Placing the patient supine with the head elevated roughly $30^\circ$ to facilitate ultrasound penetration and bowel visualization.

Mesenteric Transducer Selection

A $2\text{ to }5\,\text{MHz}$ curvilinear transducer used to achieve sufficient ultrasound acoustic penetration to reach the abdominal aortic wall depth.

Doppler Angle Criterion (Mesenteric)

Maintaining the Doppler angle at or below $60^\circ$ and parallel to the vessel wall to ensure accurate velocity measurement.

Celiac Artery Normal Waveform

A low-resistance Doppler waveform with continuous forward diastolic flow that does not change appreciably after meals due to constant hepatic and splenic demand.

Fasting SMA Normal Waveform

A high-resistance Doppler waveform with a sharp systolic upstroke and minimal or reversed early diastolic flow, reflecting low resting bowel perfusion needs.

Post-Prandial SMA Normal Waveform

A low-resistance Doppler waveform featuring markedly increased diastolic flow and increased PSV due to vasodilatation during digestion.

Normal IMA Waveform

A high-resistance Doppler waveform at rest, similar to the fasting SMA, caused by low colonic metabolic demand at rest.

Normal Celiac and SMA Velocity Threshold

A peak systolic velocity (PSV) less than $125\,\text{cm/s}$ in either vessel.

Celiac 70% Stenosis Criteria

A celiac artery peak systolic velocity (PSV) of $200\,\text{cm/s}$ or higher.

Celiac 50% Stenosis Criteria

A celiac artery end-diastolic velocity (EDV) of $55\,\text{cm/s}$ or higher.

SMA 70% Stenosis Criteria

A superior mesenteric artery peak systolic velocity (PSV) of $275\,\text{cm/s}$ or higher.

SMA 50% Stenosis Criteria

A superior mesenteric artery end-diastolic velocity (EDV) of $45\,\text{cm/s}$ or higher.

IMA 50% Stenosis Criteria

An inferior mesenteric artery peak systolic velocity (PSV) greater than $200\,\text{cm/s}$.

Mesenteric/Aortic Ratio (MAR)

The ratio calculated by dividing the SMA peak systolic velocity by the aortic peak systolic velocity.

Normal MAR Value

A mesenteric/aortic ratio of less than $1$.

Hemodynamically Significant MAR Threshold

A mesenteric/aortic ratio greater than $3$.

Diagnostic Purpose of MAR

Normalizes SMA velocity against aortic velocity to correct for systemic cardiac output variations and prevent false negatives in low-output states.

Median Arcuate Ligament Syndrome (MALS)

Extrinsic compression of the celiac artery origin by the median arcuate ligament of the diaphragm; also known as Dunbar syndrome or celiac artery compression syndrome.

MALS Expiration Dynamics

During expiration, the diaphragm rises, causing the median arcuate ligament to compress the celiac origin and markedly elevate blood flow velocity.

MALS Inspiration Dynamics

During deep inspiration, the diaphragm descends, relieving ligament compression on the celiac artery and restoring velocities toward normal.

MALS Clinical Presentation

Post-prandial abdominal pain, weight loss, and an epigastric bruit occurring classically in young, thin patients.

Fixed Elevated Celiac Velocity

A high celiac velocity that does not change with respiration, indicating intrinsic atherosclerotic plaque rather than extrinsic MALS compression.

Chronic Mesenteric Ischemia (CMI)

Peripheral arterial disease of the visceral circulation where atherosclerotic plaque narrows mesenteric vessel origins, causing post-prandial bowel ischemia.

Intestinal Angina

Periumbilical abdominal pain beginning roughly $30\,\text{minutes}$ after eating and lasting $1\text{ to }2\,\text{hours}$, caused by insufficient post-prandial blood flow.

Sitophobia

Fear of eating developed by patients with chronic mesenteric ischemia because food consumption consistently triggers severe abdominal pain.

Two-Vessel Rule

The requirement that chronic mesenteric ischemia symptoms typically require $70\%$ or greater stenosis or occlusion in at least two of the three main mesenteric arteries.

Chronic Mesenteric Ischemia Demographics

Most commonly observed in women between $40\text{ and }70\,\text{years}$ old, typically with a history of smoking or generalized atherosclerosis.

First-Line Imaging for Chronic Mesenteric Ischemia

Pre- and post-prandial duplex ultrasound of all three mesenteric vessels with MAR calculation.

Acute Mesenteric Ischemia (AMI)

A life-threatening medical emergency caused by sudden loss of bowel perfusion leading to rapid tissue hypoxia, bowel necrosis, and high mortality ($59\%\text{ to }93\%$).

Pain Out of Proportion to Exam

The cardinal physical sign of early acute mesenteric ischemia where the patient experiences excruciating visceral pain despite a soft, non-tender physical exam.

First-Line Imaging for Acute Mesenteric Ischemia

Computed Tomography (CT) Angiography.

Causes of Acute Mesenteric Ischemia

Embolism, acute thrombosis, non-occlusive low-flow states, or mesenteric venous thrombosis.

Mesenteric Collateral Network

Interconnected anatomical pathways between the CA, SMA, and IMA that maintain perfusion during single-vessel disease, making isolated single-vessel stenosis frequently asymptomatic.

Mesenteric Bypass Operative Report Review

Pre-scan chart review required to identify graft anastomoses, graft configuration, and graft material to correctly interpret flow direction.

Retrograde Flow in Mesenteric Bypass

Reversed blood flow direction within a visceral vessel segment that may represent an intended surgical result rather than vascular pathology.

Iliac-to-SMA Bypass Graft

A common mesenteric revascularization configuration featuring a proximal anastomosis on the common iliac artery and a distal anastomosis on the SMA.

Supraceliac Bifurcated Graft

A mesenteric bypass originating from the supraceliac aorta with one distal limb connected to the celiac artery and one limb connected to the SMA.

Mesenteric Stent Grayscale Evaluation

Assessing stent struts, placement, and tissue ingrowth in B-mode without color Doppler to prevent color blooming from masking wall details.

In-Stent Restenosis Sonographic Findings

Focally elevated velocities within a mesenteric stent accompanied by post-stenotic flow turbulence distal to the stent segment.

Unchanged Post-Prandial SMA Waveform

An abnormal mesenteric duplex finding where the SMA retains its high-resistance pattern after a meal, indicating fixed proximal flow obstruction.

Epigastric Bruit

An audible murmur heard over the upper abdomen, commonly associated with MALS or severe mesenteric arterial stenosis.

Left Lobe Liver Window

An acoustic technique using the left hepatic lobe as an ultrasound window to visualize the upper abdominal aorta when bowel gas is present.

Non-Atherosclerotic Mesenteric Pathologies

Less common mesenteric arterial conditions including aneurysms, arterial dissections, intimal flaps, and pseudoaneurysms.