Page 8 - Virtual Vascular Vol 6
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Complicated Acute Type B Dissection
A 60-year-old man presented with sudden onset of severe upper back pain
associated with epigastric discomfort and left lower limb numbness. Physical
examination showed high blood pressure of 220/110 mm Hg together with
absent left femoral and distal pulses
Urgent CT scan with contrast was obtained.
Figure 1 showed an acute Type B thoracic aortic dissection
In this patient, the dissection was a complicated Type B dissection as the
Thoracic aortic dissection is caused by an intimal tear (primary tear) over the superior mesenteric artery (SMA) was involved by the dissection flap and was
thoracic aorta resulting in a flap that separated the aortic lumen into true and occluded shortly after its origin- Figure 1 and 2 (arrow) (presenting with
false lumens. abdominal discomfort). There was also left common iliac artery (CIA) occlusion –
Figure 1 and 3 (arrow) with left lower limb ischaemia (numbness)
It can be classified according to Stanford Classification- Type A refers to those
with dissection flap involving the ascending aorta, while Type B refers to those Surgical intervention is indicated for complicated Type B thoracic aortic
with dissection flap NOT involving the ascending aorta. dissection. Traditionally, open surgery was required and it was associated with
significant mortality and morbidity. In the era of endovascular stent grafting,
The classification has important bearing in the management. In general, Type endovascular repair with stent graft covering the primary tear at the thoracic
A dissection requires emergency open surgery to realign the ascending aorta aorta is the treatment of choice if feasible.
to prevent early mortality, whereas type B dissection is usually treated
conservatively with anti-hypertensives unless complications arise Very often, after covering the primary tear, the malperfusion over SMA and CIA
may improve. If malperfusion persists, additional stenting procedures to the
There is increasing evidence to show that early treatment of acute type B SMA or CIA may be performed for revascularization.
dissection with a stent graft (TEVAR) may lead of better aortic remodeling
(healing) and improved long term survival. Apart from malperfusion to the visceral arteries and lower limb arteries, rapidly
8 expanding false lumen with rupture is another possible complication 9
