Chapter 81 - Aortic dissection Flashcards
Mortality of Type A+B dissection without treatment
6hr: 22.7%
24hr: 50%
1wk: 68%
Definition of acute dissection and % of mortality that happen in this time frame
2 weeks
74% of all deaths occur in 2 weeks
Subacute dissection definition
2 weeks to 90 days
flap is still pliable
Chronic dissection definition
> 90 days
septum stiff
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
Stanford 1970 classification of dissection
A: ascending tear
B: descending tear
Incidence of aortic dissection
2.9-3.5/100000 person years
Risk factors for aortic dissection
1) Age
2) HTN
3) structural abnormality
IRAD study - stands for
International registry of acute aortic dissection
INSTEAD study - stands for
Investigation of stent grafts in aortic dissection
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%
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)
Marfan accounts for this % of dissections in < 40 yr old
50%
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)
Pregnancy risk for dissection and rupture
- 4x
5. 5 / million
Dilation of aortic root above this is predictor for dissection in pregnant Marfan
4 cm
Most common site of dissection in < 40 year old
Sinus of valsalva or sinotubular junction
older people dissect in distal ascending
Contribution of cocaine to dissection
37% in urban setting as cause
1.7% in IRAD
type A and B equal distribution
Cocaine MOA for dissection
1) hypertension
2) vasoconstrictuion
3) increase cardiac output
all increase shear force dP/dt
intimal flap location distribution
Ascending 65%
Descending 25%
Arch + abd 10%
Most common site of tear in aorta
Left posterior-lateral aspect 80%
Cystic medial necrosis definition
degeneration of media in connective tissue disease
Decrease collagen and elastin
% 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
