Thoracic aortic dissection


 * Aortic dissection (1) Victoria blue-HE.jpgcic 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
 * Consequences
 * Consequences
 * 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).

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DeBakey classification

 * 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.

Clinical picture



 * 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



 * Typical history (sudden acute pain),
 * physical examination: deficiency or asymmetry of 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.

related articles

 * Thoracic aortic surgery
 * Aneurysm
 * Aortic dissection / case report

Source

 * BENEŠ, Jiří. Study materials  [online]. [feeling. 5/17/2010]. < http://jirben.wz.cz >.