Acute Dissection of the Aorta . It is when there is extravasation of blood to and along the wall of the aorta. This usually begins in the proximal aorta just above the valve or descending aorta, or somewhere in between after the origin of the left subclavian artery.
Summary
[ hide ]
- 1 Causes
- 2 Symptoms
- 3 Classification
- 4 Diagnosis
- 5 Treatment and recommendations
- 6 Sources
Causes
Dissection occurs due to injury or rupture of the inner layer of the artery wall . Two thirds of aortic dissection affects the ascending aorta or type A; the other third affects the descending aorta or type B.
In most cases, the dissection is caused by a deterioration of the arterial wall, the most frequent cause being arterial hypertension that produces a continuous pressure overload on the aorta .
Other causes include inherited connective tissue diseases (such as Marfan syndrome ), atherosclerosis , advanced age, congenital cardiovascular abnormalities, trauma, or inflammation of the aorta.
It is classified as acute dissection, if it is diagnosed within fifteen days from the onset of symptoms, and chronic dissection, if more than two weeks have passed since the onset of symptoms.
Symptoms
The pain is almost always present and is of great intensity, with sudden onset more frequently in the anterior and posterior thorax , although it may present in only one, later it runs towards the abdominal region and the hip.
Partial or total occlusion of the arteries arising from the aortic arch can give symptoms of the central nervous system, such as paralysis of the lower limbs, hemiplegia or syncope.
Peripheral pulses and blood pressures may be uneven. Murmurs over the arteries are also likely with evidence of acute arterial insufficiency.
When the dissection is close to the aortic valve, a diastolic murmur may occur, causing secondary valve and heart failure and cardiac tamponade.
Death can occur in hours, days, or weeks and is usually caused by rupture of the aorta into the pericardial sac (cardiac tamponade), the left pleural cavity, or the retroperitoneal area.
Classification
There are two classifications of aortic dissection: the De Bakey classification and the Stanford classification.
De Bakey’s recognizes three types of aortic dissection: Type I, which involves the ascending aorta, the arch and extends to the descending aorta. Type II, where the dissection is limited to the ascending aorta and arch, and Type III, when the dissection originates at the left subclavian level and extends distally.
The Stanford classification simplifies it as follows: Type A, proximal or ascending, with or without extension to the arch and descending aorta, which combines De Bakey’s types I and II. Type B distal or descending, equivalent to De Bakey’s III.
This classification is more practical since if the patient is classified as A, he or she must go to the emergency room for surgery, while B is for medical treatment.
Diagnosis
The diagnosis is based on the patient’s physical examination and medical history, as well as a series of complementary imaging tests capable of confirming his diagnosis. Decreased or absent arterial pulse in the arms and legs is detected in a large number of patients during the examination.
Imaging tests that may be performed include:
- CT (computerized axial tomography) and MRI (magnetic resonance imaging): both procedures allow us to see the morphology of the aorta.
- Transesophageal echocardiography: itis a safe and highly sensitive diagnostic technique to detect an aortic dissection.
- Aortography:This procedure is difficult to perform especially if the patient is in a serious clinical situation. It is not usually performed routinely as it is an invasive test not without risks. It consists of the administration of a contrast in the artery that can be seen in the X-ray images.
Treatment and recommendations
The first step from the medical point of view is to control hypertension, with aggressive measures even before completing the diagnostic studies. It is necessary to lower the systolic blood pressure to 100mm Hg and the pulsatile aortic flow, it is recommended to use nitroprusside and trimetaphan by venoclysis.
Intravenous propanolol, 0.15mg / kg over a period of 5 minutes, repeating as needed to keep the pulse at 60 / min. If beta-blockers are contraindicated, intravenous reserpine can be used.
All acute dissections including the ascending aorta (type A) should be treated immediately with surgery to alleviate or prevent aortic valve insufficiency and prevent rupture.
Surgical treatment is becoming increasingly popular for dissections originating in the descending thoracic aorta (type B). In this case, surgery can be delayed until hypertension and dissection have stabilized by medical means.
Since patients with type B dissection tend to be at surgical risk, permanent medical treatment may be offered. These regimens should include beta blockers and antihypertensive drugs. Vasodilators are contraindicated unless beta blockade has been performed.
