Causes of aortic dissection
The most important risk factor for aortic dissection is arteriosclerosis, a calcification of the inner vascular layer of the arteries (promoted by increasing age, smoking, diabetes, high blood lipid levels, etc.). A weakness of the tunica media (so-called media degeneration) is also predisposing for a dissection. Here, a dilatation usually occurs in the area of the ascending aorta, most often caused by high blood pressure.
More rarely, congenital connective tissue diseases such as Marfan syndrome or Ehlers-Danlos syndrome can cause weakness of the media layer. More rarely, aortic isthmus stenosis (a congenital narrowing in the area of the aortic arch) or inflammatory diseases of the aorta (so-called vasculitis) are the cause of aortic dissection. Medical interventions such as cardiac catheterisation can also promote aortic dissection. External force is rather uncommon for the development of aortic dissection, but rather leads to bruising or, in the case of strong force, to the rupture of the aorta.
Diagnosis of aortic dissection
In a patient with typical symptoms, i.e. sudden onset of back, chest or abdominal pain, the suspicion is strengthened if there is high blood pressure, a pulse or blood pressure difference between the right and left side of the body or a so-called diastolic heart murmur (which the doctor can hear with a stethoscope). If a dissection is suspected, it must be confirmed or ruled out immediately by means of suitable imaging. Computer tomography is very well suited for this purpose, as it is available in many hospitals and, in contrast to magnetic resonance imaging or angiography, takes only a few minutes.
If no CT is available, an aortic dissection can also be easily detected by echocardiography (ultrasound of the heart). This examination can also already be performed by the emergency physician if he or she has an ultrasound machine with him or her in the ambulance and can thus save important minutes. Due to the typical symptoms with sudden onset of severe chest pain, aortic dissection is sometimes difficult to distinguish clinically from a heart attack.
In this case, an ECG can be written to indicate a heart attack. In contrast, an aortic dissection does not cause any typical changes in the ECG, which only shows the electrical excitation conduction in the heart, and can often be inconspicuous even in the case of an acute life-threatening dissection. Conventional X-ray plays a rather subordinate role in the diagnosis of cardiovascular diseases.
Although an X-ray of the thorax may show indications of an acute dissection, this is not always the case. In the typical dissection patient with severe pain and unstable clinical condition, therefore, we usually do not spend any time on an X-ray. Instead, in a potentially life-threatening condition, a CT or echocardiography is immediately performed, with which the suspicion can be safely confirmed or excluded.
The D-dimer is a fibrin cleavage product which is produced during the coagulation process. The laboratory value is usually determined to exclude thrombosis. Studies have shown that a standard D-dimer value excludes aortic dissection with a probability of up to 100%. On the other hand, an increased D-dimer value is not very meaningful for the presence of an aortic dissection, since the value can increase in various diseases and the time window between the occurrence of symptoms and blood collection also plays a role. At present, imaging (CT, angiography, echocardiography, MRI) is always performed if life-threatening aortic dissection is suspected, since the D-dimer value as a laboratory value is only of indicative importance.