Patient Care - Adult cardiac, endovascular, and thoracic aortic surgery
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Aortic dissection is a tear in the wall of the aorta (the largest artery of the body). This tear causes blood to flow between the layers of the wall of the aorta and forces the layers apart. Aortic dissection is a medical emergency and can quickly lead to death, even with optimal treatment. If the dissection tears the aorta completely open (through all three layers) massive and rapid blood loss occurs. Aortic dissections resulting in rupture have a 90% mortality rate even if intervention is timely.
Aortic dissection is a condition in which there is bleeding into and along the wall of the aorta (the major artery from the heart). This most often occurs because of a tear or damage to the inner wall of the artery. Although aortic dissection can affect anybody, it is most often seen in men 40 to 70 years old. Symptoms usually begin suddenly and require prompt medical attention.
As with all other arteries, the aorta is made up of three layers. The layer that is in direct contact with the flow of blood is the tunica intima, commonly called the intima. This layer is made up of mainly endothelial cells. Just deep to this layer is the tunica media, known as the media. This "middle layer" is made up of smooth muscle cells and elastic tissue. The outermost layer (furthest from the flow of blood) is known as the tunica adventitia or the adventitia. This layer is composed of connective tissue.
In an aortic dissection, blood penetrates the intima and enters the media layer. The high pressure rips the tissue of the media apart, allowing more blood to enter. This can propagate along the length of the aorta for a variable distance, dissecting either towards or away from the heart or both. The initial tear is usually within 100 mm of the aortic valve.
Aortic rupture (a tear in the aorta, which is the major artery coming from the heart) can be seen on a chest X-ray. In this case, it was caused by a traumatic perforation of the thoracic aorta. This is how the X-ray appears when the chest is full of blood (right-sided hemothorax) seen here as cloudiness on the left side of the picture.
The risk in aortic dissection is that the aorta may rupture, leading to massive blood loss resulting in death.
Symptoms: Symptoms usually begin suddenly.
- chest pain - sudden, severe, sharp, stabbing, tearing, or ripping, located below the sternum, then radiates under the shoulder blades or to the back. May radiate to shoulder, neck, arm, jaw, abdomen, or hips, and location may change -- pain typically moves distally (to arms and legs) as the aortic dissection progresses in the same direction.
- changes in thought ability, concentration (confusion, disorientation)
- decreased movement, any location
- decreased sensation, any location
- intense anxiety, anguish
- rapid pulse (heart rate)
- profuse sweating
- dry skin/mouth, thirst
- nausea, vomiting
- dizziness, fainting
- shortness of breath (dyspnea) or difficulty breathing when lying flat (orthopnea)
- excessive yawning
- clammy skin
- weak or absent pulse
- high blood pressure
Treatment: The risk of death due to aortic dissection is highest in the first few hours after the dissection begins, and decreases afterwards. Because of this, the therapeutic strategies differ for treatment of an acute dissection compared to a chronic dissection. An acute dissection is one in which the individual presents within the first two weeks. If the individual has managed to survive this window period, his prognosis is improved. About 66% of all dissections present in the acute phase.
In all individuals with aortic dissections, medication should be used to control high blood pressure, if present.
In the case of an acute dissection, once diagnosis has been confirmed, the choice of treatment depends on the location of the dissection. For ascending aortic dissection, surgical management is superior to medical management. On the other hand, in the case of an uncomplicated distal aortic dissections (including abdominal aortic dissections), medical management is preferred over surgical treatment.
Individuals who present two weeks after the onset of the dissection are said to have chronic aortic dissections. These individuals have been self-selected as survivors of the acute episode, and can be treated with medical therapy as long as they are stable.
Medical management is appropriate in individuals with an uncomplicated distal dissection, a stable dissection isolated to the aortic arch, and stable chronic dissections. Patient selection for medical management is very important. Stable individuals who present with an acute distal dissection (typically treated with medical management) still have an 8 percent 30 day mortality.
Surgical management: The objective in the surgical management of aortic dissection is to resect (remove) the most severely damaged segments of the aorta, and to obliterate the entry of blood into the false lumen (both at the initial intimal tear and any secondary tears along the vessel). While excision of the intimal tear may be performed, it does not significantly change mortality.