Chapter 81 - Aortic dissection Flashcards by Gary Yang

Mortality of Type A+B dissection without treatment

6hr: 22.7%
24hr: 50%
1wk: 68%

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Definition of acute dissection and % of mortality that happen in this time frame

2 weeks

74% of all deaths occur in 2 weeks

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Subacute dissection definition

2 weeks to 90 days

flap is still pliable

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Chronic dissection definition

> 90 days

septum stiff

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Debakey 1965 classification of dissection

Type 1: originate in ascending, extend into descending and abdomen

Type 2: originate and confined in ascending

Type 3a: originate in descending and limited

Type 3b: originate in descending and extend to abdomen

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Stanford 1970 classification of dissection

A: ascending tear
B: descending tear

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Incidence of aortic dissection

2.9-3.5/100000 person years

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Risk factors for aortic dissection

1) Age
2) HTN
3) structural abnormality

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IRAD study - stands for

International registry of acute aortic dissection

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INSTEAD study - stands for

Investigation of stent grafts in aortic dissection

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IRAD distribution of Type A and B and age group

Type A: 60%, peak age 50-60
Type B: 40%, peak age 60-70

Male 70%
HTN 70%

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Dissection occurs more commonly in these times and other associated conditions

1) Between 6am - 12pm
2) Winter 28% > Summer 20%
3) No difference on actual climate
4) Bicuspid valve (7-14% of all dissections have this)

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Marfan accounts for this % of dissections in < 40 yr old

50%

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Aortic disease associated with dissection

1) Bicuspid valve
2) coarctation
3) annuloaortic ectasia
4) chromosome (Turner, Noonan)
5) Aortic arch hypoplasia
6) Hereditary (Marfan, Ehler-Danlos)

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Pregnancy risk for dissection and rupture

5. 5 / million

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Dilation of aortic root above this is predictor for dissection in pregnant Marfan

4 cm

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Most common site of dissection in < 40 year old

Sinus of valsalva or sinotubular junction

older people dissect in distal ascending

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Contribution of cocaine to dissection

37% in urban setting as cause
1.7% in IRAD

type A and B equal distribution

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Cocaine MOA for dissection

1) hypertension
2) vasoconstrictuion
3) increase cardiac output

all increase shear force dP/dt

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intimal flap location distribution

Ascending 65%
Descending 25%
Arch + abd 10%

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Most common site of tear in aorta

Left posterior-lateral aspect 80%

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Cystic medial necrosis definition

degeneration of media in connective tissue disease

Decrease collagen and elastin

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% of dissections associated with connective tissue disease

10-15%

Arch vessel compromise in dissection

31% of cases

Key points in looking at CTA after dissection

1) % of circumference dissection 2) distal reentry point 3) branch ostia to TL or FL

William et al description in vessel branch compromise

Dynamic obstruction 80% 1) compressed TL not enough flow 2) dissection flap prolapse into ostium Static obstruction 20% 1) dissect into the branch itself 2) thrombosis of the branch

Symptoms of dissection

Pain 93% | Abrupt onset 85%

Location of pain in Type A or B

Type A: Front chest 78% Abdomen 21% Type B: Back 64% abdomen 43%

Blood pressure in patients after dissection

HTN Type A: 25-35% Type B: 70% (most refractory) HypoTN Type A: 25% Type B: < 5%

Other symptoms after dissection

1) Syncope 5-10% 2) Spinal ischemia 2-10% (parasthesia lumbar plexus, hoarseness recurrent laryngeal, horner sympathetic) 3) Peripheral vascular 30-50%

Rate of pulse deficit after dissection and associated mortality

Brachiocephalic 14% Left CCA 21% LSCA 14% iliofemoral 35% 1) no deficit 9.4% mortality 24 hr 2) 1+2 deficit 15.8% 3) 3 deficit 35.3%

CTA sen and spe in dissection

Sensitivity 83-95% Specificity 87-100% Ascending sensitivity < 80

Rate where FL greater than TL

90%

Shape of the intimal flap

Curved 63% acutely | Flat 75% chronically

TTE sen and spe in dissection

Sensitivity 35-80% | Specificity 40-95%

Blindspot of TTE in dissections

1) Distal ascending 2) arch 3) beyond diaphragm due to trachea and left main bronchus

TEE sen and spe in dissection

Sensitivity 98% | Specificity 63-96%

MRI sen and spe in dissection

95-100% for both

Problem with using sodium nitroprusside in dissection

Reflex sympathetic stimulation --> catecholamine release --> increase dP/dt

BP target in dissection

SBP 100-120 | MAP 60-70

Type B dissection rate of complication and mortality in 15 days

12% complicated | 5% mortality

Imaging follow up for TBAD medical management

1) before discharge 2) 6 months 3) after 2 stable exams then annual

30 day mortality of TBAD

10% medical management | 30% open repair (spinal cord ischemia 32%)

False lumen enlargement rate

3.3 mm/yr

Mortality in relationship with false lumen patency

Patent FL 13.7% Partial thrombosis 31.6% complete thrombosis 22.6%

IRAD TEVAR mortality in hospital

10%

Gore TAG 08-01 study key points

1) 50 patients 2) acute complex TBAD treated with TEVAR 3) 30d mortality 8% 4) stroke 18%

STABLE study key points

1) 40 patients 2) 30d mortality 5% 3) stroke 7.5% 4) paraplegia 2.5%

SVS study key points

1) 85 patients 2) 30d mortality 10.6% 3) stroke 9.4% 4) paraplegia 9.4%

Positive remodelling rate

90% at 1 year 74% at 2 year (different study) 84% at 5 year

Malperfusion rate in TBAD

25-40%

Natural fenestration location typically

Left renal artery or other branch vessels

Open fenestration in dissection technique

1) Aortotomy 2) fenestrate or cut out flap 3) tack down branch ostia 4) close aorta with felt strips

TBAD risk of aneurysm and rupture

Aneurysm 25-50% | Rupture 10-20%

Risk factors of aneurysmal degeneration after dissection

1) HTN 2) aorta > 4cm in acute phase 3) entry tear > 10 mm 4) patency of false lumen 5) partially thrombosed distal false lumen

INSTEAD trial key points

1) Europe 2) medical vs stent in subacute/chronic TBAD 3) 140 patients randomized 4) no difference at 2 years 5) 5 year better survival in TEVAR Supported by IRAD and Durham et al study

Long term HTN control treatment target

BP < 125/80 | if Marfan then SBP < 120