3. Aortic Dissection
▪ Anatomy
▪ Definition
▪ Pathophysiology
▪ Classification
▪ Epidemiology
▪ Risk factors
▪ Clinical features
▪ Radiological and laboratory diagnosis
▪ Complications
▪ Management
▪ Long term mionitoring
4. History:
▪ First known case was King George II on October, 25,
1760
▪ First successful repair by Dr. Michael DeBakey in
1955.
Michael DeBakey at
home sewing a Dacron
artificial artery, 1955
7. Definition:
▪ Aortic dissection is defined as an intimal tear
resulting in a split in the aortic wall between the
internal and external elastic laminae within the
media
8. Pathophysiology:
Tearin the aortic intima that directly exposesan
underlying diseasedmedial layer to the driving force (or
pulse pressure)of intraluminalblood.
Thisblood penetrates the diseasedmedial layerandcleaves
themedialongitudinally, therebydissectingtheaortic
wall.
Drivenbypersistentintraluminalpressure, the dissection
processextends avariable length along the aortic wall,
typically antegradebutsometimesretrogradefrom the
siteoftheintimaltear.
9. Pathophysiology:
▪ The entry tear is defined as the point where blood
tracks through the
intima into the media.
▪ The dissection is classified by the extent of media
stripping from the
entry tear to the distal re-entry point
▪ The dissection begins with an intimal tear and is
propagated by the ingress of blood into the media
spiralling through the length of the aorta.
10.
11. ▪ Multiple re-entry tears are often present in the descending aorta.
▪ It is important to distinguish the entry tear from the extent of the
dissection as surgery forType A thoracic aortic dissection aims to
excise the entry tear but often leaves residual separated layers of
the aortic arch and descending aorta.
▪ As the entry tear is closed and the layers are joined at the distal
ascending aorta, no further blood can enter the false lumen unless
additional entry intimal tears exist within the aorta.
12. Classification :
▪ Classified on basis of duration and
location
▪ Duration :
a) acute (<14 days);
b) sub-acute (14 days - 2 months);
c) chronic (>2 months).
13. ▪ Location:
a) Stanford classification:
i)Type A: ascending aorta involved;
ii)Type B: ascending aorta not involved;
b) DeBakey classification:
i)Type I: whole aorta involved;
ii)Type II: only ascending aorta involved;
iii)Type IIIa: only descending aorta involved;
iv)Type IIIb: descending and abdominal aorta involved.
14.
15. ▪ Ascending aorta (65%) - approximately 2cm
above the non-coronary
sinus.
▪ Descending aorta (20%) - proximally on the
left anterolateral wall.
▪ Aortic arch (10%) - opposite the innominate
artery on the lesser
curve
18. Clinical features:
▪ Pain - tearing retrosternal chest pain radiating into the
back or neck.
▪ Symptoms of organ malperfusion - myocardial
ischaemia, stroke or
abdominal pain.
▪ Dyspnoea - secondary to aortic regurgitation,
tamponade or
haemothorax.
▪ Hypotension, hypertension or blood pressure
differential between the left and right arms.
▪ Aortic regurgitation murmur.
▪ Absent /asymmetrical peripheral pulses
19. Laboratory Diagnosis :
▪ Decreasesin the hemoglobinandhematocrit are
ominousfindingssuggestingthedissection
eitheris leakingor hasruptured.
▪ BUNandcreatinineareelevatedifthedissectioninvolves
the renalarteries.
▪ Hematuria,oliguria,andevenanuria(<50mL/d)may
occurifthedissectioninvolvestherenalarteries.
▪ CKMBandTroponinTmaybeelevatedinacutethoracic
aortadissection
▪ Lacticaciddehydrogenaseincreasedueto
haemolysis.
21. Radiological Diagnosis :
▪ Transoesophageal echocardiography (TOE, 98%
sensitive) provides clear images and is able to
quantify the degree of aortic regurgitation
but:
a) results are operator-dependent;
b) passing theTOE probe may cause anxiety and
hypertension;
c) there is a blind spot in the distal ascending aorta
and proximal aortic arch.
22. 1.Freely movable flap within the lumen of the vessel
2.Differential Dopplerdetection of true v.s.falselumen
23. ▪ Computed tomography with contrast
enhancement (95% sensitive)
is quick, commonly available and can image
the pleura, head and
neck vessels, and pericardium, but the
patient is at risk of contrast
nephropathy
24. ▪ Magnetic resonance imaging (99%
sensitive) is the gold standard
imaging but is not always available.
▪ Aortography (80% sensitive) was
historically the gold standard but
now is rarely used and may precipitate
aortic rupture.
25. • Intimal flap
Slowflow andclot in falselumen
Lumen Partition
of a three-
dimensional
contrast-
enhanced MRA
shows intimal flap
(arrows ) in the
distal aortic arch
and descending
aorta.
30. ▪ Surgical Management :
–Type A aortic dissection requires urgent
surgical treatment, particularly when the
patient presents within the first 48 h,
unless there are formal contraindications,
and especially if there are serious
irreversible cerebral or visceral injuries
31. Surgical Goals:
▪ Entry tear - resect and replace the site of the aortic entry tear.
▪ Aortic root - to prevent coronary malperfusion and late aortic root
complications, surgery can either:
a) repair the aortic sinus segments by adhesive reconstruction to
obliterate the false lumen; or
b) replace the aortic root.
▪ Aortic valve - resuspension or replacement of the aortic valve.
▪ Aortic arch - hemi-arch or total arch replacement depending on
whether the entry tear has extended into the aortic arch.
▪ Distal anastomotic line - adhesive reconstruction at the distal
anastomosis to obliterate the false lumen and restore flow through
the true lumen.
32. ▪ The different surgical options include:
a) ascending aorta interposition graft;
b) ascending aorta interposition graft and aortic valve
replacement;
c) ascending aorta interposition graft and resuspension of the
aortic valve;
d) aortic root replacement (Bentall or Cabrol);
e) valve-sparing aortic root replacement (Yacoub or David)
f) in addition, hemi-arch or total arch replacement.
33.
34. ▪ The underlying principle of surgery for these
patients is to prevent the life-threatening
complications of acuteType A aortic dissection,
which include
– intra-pericardial rupture
– Tamponade
– myocardial ischaemia
– aortic regurgitation.
▪ Mortality without surgery approximates 90%,
▪ surgical mortality ranges between 10-20%.
▪ Five-year survival of hospital survivors following
surgery is 60%
35. Management( type B aortic dissection )
▪ Medications
– control the pain and lower systolic blood pressure
110mmHg.
– morphine sulphate
– intravenous beta-blockers (metoprolol, propranolol, or
labetalol)
– vasodilator drugs such as nitroprusside or ACE
inhibitors.
– If beta-blockers are contraindicated, use calcium
antagonists such as verapamil or intravenous diltiazem
36. ▪ The rationale for NOT OPERATING on allType B
aortic dissections is:
– the mortality with medical management is 10%
compared with an operative mortality of 27% and an
operative paraplegia rate of 24%;
– the 5-year survival is not improved with surgery.
37. Indications for surgery in Type b
aortic Dissection :
▪ Rupture or impending rupture of the descending
thoracic aorta (large mediastinal haematoma, large
haemothorax).
▪ Extension of the dissection with unremitting pain.
▪ Evidence of limb, visceral or spinal cord
hypoperfusion - metabolic
acidosis, raised lactate, oliguria or anuria,
paraesthesia or paraplegia
in the lower limbs
40. Add a Slide Title - 5
Replacement of the
descending aorta
using a Dacron®
interposition graft,
following rupture of
aType B aortic
dissection
41. Because of the high operative mortality in patients with
renal or visceral artery compromise from dissection,
endovascular approaches are under investigation
from dissection, re under investigation
42. Long-Term Monitoring
At 1 month, a follow-up check for any new
symptoms, such as chest or back pain, and signs
suggestive of progression of the aortic dissection
Adequate blood pressure control, with systolic
blood pressure maintained at 90-120 mm Hg
Routine chest radiographs, CT with contrast, and
MRI at 3-, 6-, and 12-month intervals, respectively,
in an outpatient setting to evaluate any progression
of the condition
