Module 2 : Vascular Structures Flashcards
The cardiac cycle
Arteries with O2 take blood from left ventricle to muscles
Veins return without O2 from muscles to right atrium then right ventricle
Right ventricle to lungs to get O2
O2 blood returns to left atrium
Composition of Arteries AND veins
3 layers - coat or tunica
- Tunica intima (interna)
- innermost
- endothelial lining and elastic tissue - Tunica media (middle layer)
- elastic fiber and smooth muscle
- thicker in arteries than veins (withstand pressure) - Tunica adventitia (externa)
- outermost
- elastic and collagen fibers
Differences between arteries and veins
- Arterial wall thicker (tunica media)
- Arteries maintain shape
- Venous diameter varies with breath
- Arteries influenced by heart contractions
- Veins influenced by muscle contractions, pressure gradients, breathing
- veins have larger total diameter
- blood flow slower in veins
Anatomy of aorta
- retroperitoneal
- pierces diaphragm at aortic hiatus at T12
- anterior to spine and left of midline
- moving caudal becomes more anterior and tapers distally
Anatomical relationships - anterior to ao
- crura of diaphragm
- celiac axis
- lesser sac
- SMA
- left Renal Vein
- body of Panc
- ima
- splenic vein and artery
- left lobe of liver
Anatomical relationships - lateral to aorta
Crura of diaphragm
Anatomical relationships- anteroleft
GE junction
Branches of aorta
- celiac axis
- superior mesenteric artery
- right and left renal arteries
- right and left gonadal arteries
- inferior mesenteric artery
- common iliac artery
Celiac axis
- within 2 cm of aorta
- celiac trunk
- T or Y shaped
- 3 branches
+ common hepatic, left gastric, splenic - each branch supplies multiple but primary to their name
Left gastric artery
- not well seen
- anterior and superior course
- descends along lesser curvature of the stomach
- smallest
Common hepatic artery
- horizontal path to the right
- superior to Panc Head
- enters liver at porta hepatis (turns anterior)
- anterior to MPV
- gives of gastroduodenal artery and becomes hepatic artery proper
- divide into left and right hepatic artery within the liver
Branches of hepatic artery
Gastroduodenal
Right gastric
Cystic
Gastroduodenal artery
Courses caudally posteromedial to duodenum
Landmark for anterolateral aspect of Panc head
Cystic artery
Arises rom right hepatic artery
Supplies gallbladder, CBD, andnhepatic ducts
Splenic artery
- travels left toward spleen
- largest of three branches
- tortuous
- posterior and superior to panc
- supplies blood to Panc, spleen, stomach
Superior mesenteric artery (SMA)
- anterior surface 1cm inferior to celiac axis
- posterior to Panc body
- anterior to uncinate and third part of duodenum
- courses inferiory
- blood supply for right small bowel and large bowel
Renal arteries
- slightly inferior to SMA
- RRA runs posterior to IVC
- RRA longer than LRA
- several branches at the renal hilum
Gonadal arteries
- not typically visualized
- anterior aorta
- inferior to renal arteries
Inferior mesenteric artery (IMA)
- last major branch
- anterior aspect
- courses inferior and left
- supplies transverse descending and sigmoid and rectum
- not usually seen
Common iliac arteries (CIA)
- bifurcates at L4 or belly button
- inferior and posterior diving into internal and external iliac
- CIAls lie anterior and lateral to CIV
Measurements - aorta
- AP measurement
- level of the diaphragm: 2cm approx
- level of bifurcation: 1.5cm
- AP greater than 3cm means aneurysmal
Measurements - iliac arteries
- men: 1.4-1.5 cm
- women: 1.2 cm
Sonographic appearance - sag ao
- anechoic tube
- echogenic walls
- tapers inferiorly
- celiac and SMA anterior
- pulsation
Sonographic appearance- trans ao
- anechoic round
- echogenic walls
- spine posterior
- celiac axis T or Y
- SMA round anechoic
- renals just inferior and lateral long axis
- iliac arteries two anechoic round
3 windows
- midline
- left and angle back toward midline
- left coronal distal
Right coronal proximal
Patient prep
Overnight fast
Probe and preset
2.5 - 5 MHz curvilinear
Preset depends on body of patient
Scanning techniques
- patients scanned in supine
- start is subxiphoid
- focus gain TGC’s
- asses and image entire ao in sag and trans
- coronal plan is option
Anatomy of IVC
- largest vessel that returns blood to the heart
- formed by union of the common iliac vessels at level of L5
- retroperitoneal
- courses cranially through diaphragm on right
- enters right atrium
- many tributaries
- size variable
- DILATED GREATER THAN 2.5CM OR 3.7
Renal veins
- enter lateral aspect of IVC
- anterior to renal arteries
- right Renal vein shorter
- left Renal vein anterior to aorta posterior to SMA
Gonadal veins
- right empties into IVC
- left into left renal vein
Lumbar veins
- branches of common iliac or IVC
- travel late4al to spine posterior to psoas
Hepatic veins
- 3 Veins= left middle right
- drain blood from liver
- drain into IVC just inferior to IVC and diaphragm
- increase in size closer to IVC
- no valves
Sonographic appearance of IVC
Sag - anechoic tube - right of midline - responds to breathing - walls not as echogenic Trans - oval shaped anechoic - IVC should collapse with inspiration and expand during expiration - suspended causes it to expand
Sonographic of hepatic veins
- best demonstrated in transverse
- angle cephalad
- play boy bunny or rabbit ear
- increase in size close to IVC
Sonographic renal veins
- visualized at same level as renal arteries
- best in transverse
- anechoic
Portal venous system
- not tributaries of IVC
- drain blood from bowel, spleen, pancreas, gallbladder, bile ducts
- traverse liver and drain into hepatic veins
- no valves
- formed by union of splenic vein SMV I MV
Splenic vein
- originate at root of mesentary
- parallels to SMA and lies to the right
- anterior to uncinate process
Inferior mesenteric vein
- difficult to see
- drains into splenic vein
Main portal vein
- formed by union of SMV and splenic vein @ portal confluence
- posterior to Panc neck
- diameter 11mm but less than 13mm
- travels to right superior and oblique
- enter liver hilum at porta hepatis
- divides into right and left at porta hepatis
- supplies 50-60% of oxygen to liver cells
Left portal vein
- anterior surface of caudate lobe then turns anterior
- divides into medial and lateral branches
- steers Head
Right portal vein
- shorter and fatter
- posteriorly and caudally
- divides into anterior and posterior branches
- long axis of RPV identified in transverse plane
Sonographic appearance portal veins
- sag and transverse
- splenic as reference for trans, follow until increased size then turn 90’ and length of SMA seen
- MPV travels obliquely
- echogenic walls
- do not collapse
Normal spectra, waveform for IVC
- phasic (with respiratory changes)
- bidirectional, pulsitile
Spectral waveform - hepatic vein
- phasic, pulsatile
- flow away from liver
Spectral wave form - renal vein and artery
Artery
- low resistance
Vein
- phasic flow variations
Spectral wave- portal veins
- phasic and continuous
- normal flow toward liver HEPATOPEDAL
- some conditions reverse direction of flow HEPATOFUGAL
Spectral wave - aorta
- moderate resistance flow above renals
- low resistance below renals
