Histopathological picture of thoracic aortic dissection in a patient without Marfan's syndrome. The damaged part of the aorta was surgically removed and replaced with a vascular prosthesis. Victoria blue and HE staining.Thoracic aortic dissection is a sudden vascular event with a dramatic course, immediately life-threatening.
Pathogenesis
The cleavage of the aortic wall caused by the penetration of blood through the crack in the intimate and media.
The rupture occurs most often above the coronary arteries or in the aortic isthmus.
From the site of the crack, the dissection can spread peripherally and centrally, it can affect the whole circumference or only a part. The canal can also spread to the carotid or visceral branches of the aorta.
At the end of the dissection, another reentry may occur and a communicating channel is created.
Consequences
The canal oppresses the right aortic lumen even at intervals.
The dissection created above the coronary arteries often spreads centrally and tears the commissures of the aortic valve, resulting in severe insufficiency.
Causes
Degenerative media changes ( cystic medionecrosis ) or aneurysm in combination with hypertension , less often atherosclerosis .
We often encounter it in Marfan's syndrome (young patients) and in other systemic connective tissue diseases ( Ehlers-Danlos syndrome , Loyes-Dietz syndrome ).
Other predisposing factors include bicuspid aortic valve , aortic coarctation or trauma (falls, car accidents).
Type I - begins in the ascending aorta and continues to the abdominal,
Type II - bounded on the area of the ascending aorta,
Type III - begins in the aortic isthmus and affects the descending aorta, or. continues to the abdomen.
Stanford classification
Type A - the ascending aorta is affected (2x more common than type B),
Type B - affected is the descending aorta.
CT dissection of the aneurysmal ascending aorta
CT dissection of the descending aorta
Clinical picture
Autopsy finding - aortic dissection
Sudden shocking pain behind the sternum and back can progress to the abdomen.
Sometimes a shock condition follows ( bleeding , tamponade , acute heart failure) - they usually die of sudden death.
Sometimes the symptoms gradually subside and the condition stabilizes temporarily or permanently.
Vascular symptoms:
different, depending on which aortic branches are oppressed or torn off,
cranial arteries - unconsciousness, hemiparesis,
subclavia - ischemia HK,
upper mesenterics - intestinal ischemia,
renal arteries - anuria , oliguria ,
peripheral arteries - deficit or asymmetry of pulsations (typically variable over time), lateral asymmetry of pressures on HKK, etc.
Diagnosis
ECHO (longitudinal section) finding of aortic dissectionCT 3D dissection angiography - right and false lumen
Typical history (sudden acute pain),
physical examination: deficiency or asymmetryof pulsations in peripheral arteries,
auxiliary methods:
exclusion of AIM ( ECG ),
Chest X-ray - extension of the shadow of the upper mediastinum to the left,
ECHO , CTA , aortography.
The sovereign method - transesophageal echocardiography - determines the diagnosis in 98%.
Indications for operation
By type, extent, vascular disability and general condition:
for type A, about half of the victims die within 24 hours, the hope decreases with each passing hour → type A is always indicated for immediate surgical treatment,
for type B, we choose a predominantly conservative procedure if there is no vascular symptomatology or there is no risk of rupture.
Therapy
Immediately after the diagnosis, we start drug treatment: antihypertensives , beta blockers and vasodilators , diuresis support . We monitor the patient, administer analgesics (insufficient pain treatment leads to antihypertensive failure). Cardiac tamponade should be ruled out by echocardiography in patients with hypotension.
Type A
Principle of operation - we try to cancel the inflow into the aneurysm, several methods:
transverse intersection of the ascending aorta at the site of the rupture, suturing of both ends of the aorta over the outer and inner meshes, subsequent suture of the aorta,
resection of the ascending aorta, strengthening of the ends with a suture and replacement of the aorta with a prosthesis,
Bental's operation - replacement of the aortic valve and ascending aorta by a conduit with a valve, implantation of coronary arteries into the prosthesis,
closing the entrance to the dissection with tissue glue with aortic suture or with a prosthesis,
implantation of an intraluminal ring prosthesis into the ascending aorta.
Type B
We treat uncomplicated type B dissection conservatively (stabilization, antihypertensives).
For complicated dissections, it is necessary to proceed to invasive treatment:
endovascular stent graft implantation,
surgical solution.
Principle of surgical treatment
In the right flank, from a left thoracotomy, usually without ECC, a bypass is sometimes used to protect the kidneys and spinal cord from ischemia .
Resection of a section with a crack, replacement with a prosthesis, or implantation of an intraluminal prosthesis - this will cancel the entry and it will close with thrombosis. The operation is more complicated when the visceral arteries leave the dissection canal - a laparotomy must be performed and those arteries reconnected to the aorta.
Complication
Stanford A dissection can cause acute aortic insufficiency, heart failure, hypotension. Closure of the coronary arteries by dissection leads to AIM (most often a diaphragmatic infarction occurs by occlusion of the ACD ). Rupture of the pericardial dissection creates a cardiac tamponade.
Stanford B dissection can be complicated by spinal, visceral, renal or limb ischemia.
ZEMAN, Miroslav, et al. Special surgery. 2nd edition. Prague: Galén, 2006. 575 pp. ISBN 80-7262-260-9 .
ČEŠKA, Richard, ŠTULC, Tomáš, Vladimír TESAŘ and Milan LUKÁŠ, et al. Internal. 3rd edition. Prague: Stanislav Juhaňák - Triton, 2020. 964 pp. ISBN 978-80-7553-780-5 .
Source
BENEŠ, Jiří. Study materials [online]. [feeling. 5/17/2010]. < http://jirben.wz.cz >.
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CT dissection of the aneurysmal ascending aorta
CT dissection of the descending aorta
