Aortic Dissection, and its Complications

Aortic Dissection, and its Complications

Dominik FleischmannDepartment of RadiologyStanford University

Dominik FleischmannDepartment of RadiologyStanford University

20th Annual Summer Practicum, Masters in Body ImagingJackson Lake Lodge, Moran, Wyoming

August 8-11, 2010

Research support: General ElectricSpeaker's board: Bracco

Siemens

Dominik FleischmannDepartment of RadiologyStanford University

Dominik FleischmannDepartment of RadiologyStanford University

Conflicts of Interest Disclosure

20th Annual Summer Practicum, Masters in Body ImagingJackson Lake Lodge, Moran, Wyoming

August 8-11, 2010

Background & Clinical Context

Acute aortic syndrome:

acute life-threatening abnormalities of aorta assoc. with intense chest or back pain, traditionally include:

Aortic dissection (AD), Intramural hematoma (IMH), Penetrating atherosclerotic ulcer (PAU)

RARE: 2.6-3.5 /100k/yr in US

(440 /100k/yr for myocardial infarction)

LIFE THREATENING

DIAGNOSIS/MANAGEMENT: IMAGING BASED

• 40% die immediately (~50% within 48 hrs) mainly from rupture

• 2% per hour mortality (1-3% die in hour before surgery)

• end-organ malperfusion occurs in 16-30%, dramatically reduces survival

• short term (in-hospital and 30 day) mortality: 3.4% - 25%

Acute aortic syndromes

Natural History of Type A Dissection(approx 60% of dissections are Type A)

Acute Aortic Syndromes Imaging Strategy

Precontrast series • mandatory in acute setting

CTA series• CTA chest-abdomen-pelvis scanning range: thoracic inlet femoral a. bifurcation !!

• Gated chest + (abd.-pelv. non-gated CTA)

3mm/3mm

Thick./Rec.-Int.

1mm/0.7mm

Acute aortic syndrome: MUST HAVE non-contrast acquisition

• 62 year old man with hypercholesterolemia and hypertension;

• in morning squeezing chest pain, back pain

non contrast CT

Intramural Hematoma

Acute Type B DissectionEvaluation of femoral artery access for

intervention

left femoral a.: true lumen

right femoral a.: false lumen

Clinical 3D and 4D Imaging of the Thoracic Aorta

49 year old man

acute chest pain;

RR 170 / 20

Gated CTA of chest (+ abd pelv)

• r/o aortic disease

CT of the Thoracic Aorta

with ECG gating

Copyright ©1999 American Heart Association

Sven

sson

, L.

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et

al. C

ircu

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on 1

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Top, TEE of patient 2 whose initial clinical presentation was suspicious for aortic dissection but in whom no dissecting flap or hematoma was found, although aortic aneurysm was noted

Dissection variant: Limited Intimal Tear

72 y.o. man, aneurysmal ascending aorta, chest pain

lumenAdventita

MediaIntima

Aortic Dissection: Manifestation of a Diseased Media

‘cystic medial necrosis’• elastolysis (elastic & collagen fiber loss)

• mucoid degeneration • smooth-muscle cell loss and

dedifferentiation Fedak, P. W.M. et al. Circulation 2002

Elastic Lamina of Aortic Wall

• Marfans (fibrillin)• Ehlers Danlos IV (collagen)• familial TAA• severe hypertension !!!!• normal aging

Classic Aortic Dissection• false lumen within the media

'intimal flap'=inner 2/3 of med + intima intimo-media flap

truelumen

falseAdventita

MediaIntima

• entry tear (primary intimal tear [PAI]• exit tear(s) ['reentry tear',

fenestrations]

Acute Type–A Dissection

CTA

primary intimal tear true / false lumen (DSA)

DSA

IMH BI^V

True versus False Lumen

VA^C

tttt t

normal

f f f f f

'typical' TL collaps

True versus False Lumen

VA^C

tttt t

normal

f f f f f

intima-intussusception

'typical' TL collaps

'complex' ‘pseudonormal’

45 y/o man

• 3 wks dyspnea, no 'pain'

• on TTE: type A dissection

45 y/o man

• 3 wks dyspnea, no 'pain'

• on TTE: type A dissection

Small PIT

Prolapse

Primary Intimal Tear (PIT)

Large / Circumferential PIT

Intimal intussusception

48 yo man

• hx of crack cocain use;

• outside hx of type-A IMH which was evacuated, but not repaired

Aortic Dissection

Stanford ClassificationAortic Dissection

Stanford Classification

Type A Type B

asce

nd.

invo

lved

asce

nd.

not

invo

lved

Type A dissection/IMH

75 y/o hypertensive man, acute chest pain,

and left hemothorax

05-Dec

Treatment with descending ao. Stentgraft

desc.ao. intimal tear

17-Dec

Aortic Dissection

Stanford Classification Subclass. site of tear)

Type A: intimal flap involving ascending ao.

immediate surgery

subtype: asc / arch / desc / other [no])

Type B: no involvement of asc.ao.

conservative, unless complicated

subtype: arch / desc / other [no])Daily PO et al, Ann Thorac Surg. 1970;10:237-247

Primary intimal tear important !

endovasc. treatment target

Aortic Dissection – Stanford Subclassification

168 patients operated for acute dissections

(* arch in 10 of 11)(Lansman, Griepp; Ann Thorac Surg 1999;67:1975–1978)

Asc. Arch Desc. Mult.* None

TYPE A (n=139)

83 (60%)

31 (22%)

8 (6%)

11 * (8%)

4 (3%)

TYPE B (n=29) n/a 1 21 0 2

Sta

nfo

rd T

YPE

Subclass. site of tear)

1/3rd 'retro-A'

Acute Aortic Dissection

Complications

• (contained) rupture, leakage tamponade; aortic regurgitation (Type A)

• side branch malperfusion syndromes:

(in approx. 1/3rd of acute type A diss), substantially reduces survival

Type A: coronary, cerebral + ...

Type A&B: renal, mesenteric, peripheral, paraplegia

Aortic DissectionSide-branch Malperfusion

Mortality coronary arteries ~ 25% cerebral arteries/parapl. ~ 45%

renal (ATN, hypertens.) ~ 50-70 % mesenteric ~ 50-95 % peripheral (extremity) ~ 45 %

Diagnosis• clinical• labs

CT cannot diangose mal-perfusion !!

Aortic DissectionSide-branch Malperfusion

Possible mechanisms• local obstruction at branch ostium• limited in- (out-)flow into true (or false)

lumen

Role of CT in side branch malperfusion once diagnosis is established/suspected

• identify detailed anatomy to infer and• explain mechanism ('flow')

treatment consequence !

False Lumen: In- Outflow

How does blood get ?

into the false lumen, and - Primary Intimal Tear (*PIT)

out of the false lumen - side branches off FL

- Re-Entry Tear (**RET)

PIT*

RET**

branch a.(renal)

(inter-costal)

Aortic dissectionwith true lumen collapse

mesenteric and renal ischemia

Intima

Aorta

Type B dissection with TAAA

Type B dissection

• true lumen collapse,left renal artery occlusion with stent-placement

Local Side Branch Involvement in Dissection

natural fenestration('reentry tear', if large)

loca

l flow

-lim

itin

g lesi

on

s

diss. ext. into branch(es) /w stenosis

torn flap within branch /w stenosis

windsock in branch /w stenosis/occlusion

un

com

pli-

cate

d

average IP

acute bowel ischemia52 y/o hypertensive man• acute type B dissection

51 y/o man, Marfan's• pulsless legs• hx of aortobifemoral graft

Acute Type B Dissection

False lumeninjection

TL collapse

IMA(reimplanted into aortobifemoral graft)

FL('windsock')

Diagnostic information sought in patients Acute Aortic Syndromes

SUMMARY

• lesion detection, characteriz. (AD, IMH, PAU) incl. signs of leakage / rupture

• involvement of ascending aorta (type A vs B) pericardial effusion involvement of coronary arteries / aortic valve

apparatus

• location of entry tear (or ulcer, if PAU)

• distal extent (anatomic) for roadmap

• side branch involvement / mechanism

Acute aortic syndromes

Aortic dissectionClassic aortic dissection Intramural hematomaDissection variant 'limited tear with aortic bulge' = 'dissection without intimal flap' = 'subtle/discrete dissection

Intramural hematoma (NO DISEASE)

Penetrating atherosclerotic ulcerwith intramural hematoma

(Traumatic transection)(Rupturing/leaking aneurysm)

Dise

ase

d m

ed

iaD

isease

d

intim

a

Semin Thorac Cardiovasc Surg 2008 (Dec) 20:340-347