Thoracic Aorta

Question 1

Thoracic aorta divided into 4 parts

Answer 1

Aortic root
•AV annulus, cusps, SoV, STJ
•dimensions include: annulus, sinuses, STJ

Ascending aorta
•begins at STJ and extends to origin of brachiocephalic artery

Aortic arch
•includes arch vessels and extends to the isthmus between origin of subclavian and ligamentum arteriosum

Descending aorta
•distal to the origin of the left subclavian artery and ligamentum arteriosum and continues to diaphragm

Question 2

Aortic dimensions

Answer 2

Aortic annulus: 2 - 2.5 cm

Sinus of Valsalva: 3 - 3.5 cm

Sinotubular Junction: 2 - 2.5 cm

Ascending Aorta: 2.2 - 3.7 cm

Aortic Arch: 2.5 - 3.0 cm

Descending Thoracic Aorta: 2.0 - 2.5 cm

Question 3

TEE views of aorta

Answer 3

ME AV LAX — good view for measurements, AI, dissection flap

ME Asc Ao LAX — pull probe back from LAX view until RPA in cross section

ME Asc Ao SAX — 0-30 deg, pull probe back to 25cm and anteflex

Descending Ao SAX — rotate probe left from ME4C and move up / down to evaluate dissection + plaque

Descending Ao LAX — 90 deg from SAX view to evaluate dissection, plaque, thrombus

UE AA LAX — pull probe back from SAX view to 20 cm and slight rotation to left

UE AA SAX — 90 deg and orthogonal to LAX to identify takeoff of left subclavian and assess PV

Anatomical blind spot due to tracheobronchial tree between esophagus and aorta typically at location of cannulation and cross clamping — evaluate with epiaortic scanning

Question 4

Aortic dissection classification

Answer 4

Ascending aorta
•DeBakey Type I and II —> Stanford Type A
•50-85% of cases
•90-95% non surgical mortality
•3.5-10% surgical mortality at experienced centers

Descending aorta
•DeBakey Type IIIa and IIIb —> Stanford Type B
•40% non surgical mortality

Question 5

TEE evaluation of aortic dissection

Answer 5

1. Locate origin of intimal tear and determine extent of dissection
2. Confirm presence of dissection flap
3. Separate true and false lumens :
   •true lumen has higher systolic velocity
   •false lumen has echo evidence of stasis or thrombus
   •intimal flap moves toward false lumen in systole
   •high velocity jet flows from true lumen to false lumen during systole

4. Assess for collateral damage
•AI ? How severe ?
•injury to arterial branches of aorta
Common carotid — 14.5%
Renal artery — 12%
Mesenteric artery — 8.2%
Coronary artery — 7.5%
•presence of pericardial / pleural effusion

Question 6

Distinguishing flap from artifact

Answer 6

• confirm presence of dissection flap from several angles and transducer locations
• confirm dissection flap has a motion independent of surrounding structures
• confirm apparent flap is contained within the aortic lumen
• demonstrate flow on both sides of the flap with CFD — laminar flow in true lumen

Question 7

Studies for aortic dissection

Answer 7

Sensitivity:        Specificity:
TEE   88 - 98%.         90 - 95%
TTE   77 - 80%.         93%
CT     94%.                 87%
MRI* 98%.                 98%

MRI > Helical CT > TEE > CT > TTE

Question 8

Thoracoabdominal aneurysm Crawford classification

Answer 8

Type I: distal to left subclavian artery to above the renal arteries

Type II: distal to left subclavian artery to below the left renal artery

Type III: 6th intercostal space to below left renal artery

Type IV: total abdominal, 12th intercostal space to iliac bifurcation

Type V: 6th intercostal space to just above renal arteries

Question 9

TEE evaluation of aneurysm

Answer 9

1. Origin and extent of aneurysm
2. Size of aneurysm
   •Internal diameter is measure such that it is perpendicular to axis of blood flow
   •CT/MRI measures external diameter
3. Intraluminal thrombus
4. Collateral injury

Question 10

Thoracic Aortic Atheromatous Disease

Answer 10

Strong risk factor for perioperative stroke (2-3%) following manipulation

High Se and Sp of TEE and epiaortic echo

Grading:
Grade I: normal
Grade II: < 3 mm
Grade III: 3-5 mm
Grade IV: > 5 mm
Grade V: mobile