Typical for aortic dissection is a sudden pain of destruction, which is perceived as stinging or tearing. The localization of pain is usually in the chest area, but often also in the back and abdomen area.
If you experience these symptoms, contact an emergency doctor immediately and describe them!
Depending on which blood vessels leading from the aorta are closed by the dissection, symptoms of a reduced blood supply to the organs involved also appear. This manifests itself in severe abdominal pain in the case of circulatory disorders in the intestine or kidneys. In some cases, circulatory disorders can also lead to symptoms of a stroke.
The clinical picture of aortic dissection is tricky because it can easily be misinterpreted by emergency physicians as a (much more common) heart attack, which in the worst case leads to incorrect initial treatment. A reliable diagnosis is usually only possible with the help of computer tomography.
Causes of Aortic Dissection
Mechanisms that weaken the aortic wall layers can lead to increased wall stress and ultimately to wall bleeding or dissection via aortic dilation. Arterial hypertension (72.1%) plays a major role among the acquired causes. In addition to arterial hypertension, atherosclerosis (31%) and diabetes mellitus (5.1%) are other risk factors. Iatrogenic aortic dissections occasionally result from invasive catheter interventions or after surgery.
The most important inherited connective tissue diseases with involvement of the aortic wall are Marfan syndrome (MFS) and Ehlers-Danlos syndrome (EDS) as well as the familial form of thoracic aortic aneurysms and aortic dissections. MFS is the most common congenital connective tissue disorder with an incidence of 1 in 7,000 with autosomal dominant inheritance. The diagnosis of the MFS is based on clinical criteria and molecular genetic diagnostics. Hereditary connective tissue diseases are summarized under the EDS, all of which are characterized by increased mobility of the joints and tissue fragility. The exact incidence of the 11 forms of EDS is not known. The most common type is the autosomal dominant type 4 (“vascular type”) of the EDS.
Classification of Aortic Dissection
In the case of acute aortic dissection, the intima tears and, in part, the media (entry) with splitting of the aortic wall. In most cases the detachment of the inner layer follows in the direction of the blood flow. The result is two lumens with flow through them, which are separated from each other by a dissection membrane. True and false lumens, including the dissection membrane in between, often pull helically, according to the blood flow, in the aorta, in the craniocaudal direction.
According to the Stanford classification, a distinction is made between type A aortic dissections involving the ascending aorta and type B aortic dissection, in which the tear is distal to the exit of the left subclavian artery and the ascending aorta is by definition not affected , This classification says nothing about the re-entry, that is, the distal tear in which the blood flows from the wrong lumen back into the true lumen. The preliminary stages of aortic dissection such as intramural hematoma, penetrating ulcer or localized intimal detachment are not taken into account in the Stanford classification.
Course and Forecast
Type A aortic dissection
If left untreated, a patient with acute type A aortic dissection has a 40 to 60% risk of dying in the first 48 hours after the event. For this reason, it is vital to operate immediately. If left untreated, patients usually die from rupture of the wrong lumen or from the consequences of an acute pericardial tamponade. Other complications include acute, severe aortic valve insufficiency or malperfusion of the aortic branches. The latter can lead to acute myocardial infarction, cerebral ischemic insult, paraplegia, acute visceral or renal ischemia, or acute peripheral limb ischemia.
Type B aortic dissection
Patients with conservatively treated type B aortic dissection have a 30-day lethality of around 10%, whereas for patients with complications that previously gave rise to open surgery, the mortality rate is around 20% on the second day and around 30% after one month. Old age, shock and malperfusion predispose to an increased early mortality. Due to the weakened aortic wall, aneurysms can arise in the long term after aortic dissections, usually starting from the wrong lumen. Re-dissections and progression of the original aortic dissection or aortic rupture can also occur.
Diagnostic of Aortic Dissection
Clinical symptoms
Acute aortic dissections usually occur with sudden stabbing back pain (53%), with the pain along the aortic course often pulling in the craniocaudal direction (17%). If aortic dissection is suspected, transport to the heart and vascular center accompanied by the emergency doctor must take place immediately. Due to the time pressure, the diagnostic clarification in the clinic must be limited to securing the diagnosis of aortic dissection.
Symptoms of malperfusion arise depending on the side branches of the aorta involved. Some of the patients with type A aortic dissection have syncope (13%) due to pericardial tamponade with circulatory collapse (13%) or neurological symptoms (6.1%) with involvement of the carotid artery. If heart failure (8.8%) develops after an initial pain event, acute aortic valve insufficiency (44%), a heart attack due to coronary dissection or a pericardial tamponade (13%) can be the basis. Ischemia syndromes in the periphery (19%) are the result of side branch occlusions through the dissection membrane.
Paraplegia can develop when a critical number of intercostal arteries are compromised by the dissection membrane. A closure of the celiac trunk and especially the superior mesenteric artery must be suspected if abdominal pain suddenly occurs (30%). In acute kidney failure, one should think of a dissection-related flow impairment of the renal arteries. Pulse deficits (19%) or side differences in pulse quality are significant because they mark the extent of aortic dissection and correlate with the prognosis.
Diastolic noise as an expression of aortic valve insufficiency (44%) may indicate acute type A aortic dissection. Clinical signs of pericardial effusion or pericardial tamponade (13%) in the form of congested cervical veins, paradoxical pulse and arterial hypotension (12%) are alarm signals for type A aortic dissection and must be treated with surgery immediately after confirmation of the diagnosis using transthoracic echocardiography or CT ,
The differential diagnosis of acute aortic dissection should always be used in patients with unexplained syncope (13%), chest (61%) or back pain (53%), abdominal pain (30%), stroke (4.7%), or acute heart failure (6.6 %) should be considered. Differently side pulses (15%) or signs of mal perfusion are special suspicions (2, 15–17).
Imaging diagnostics
Since thoracic aortic dissection can also be present with a normal chest x-ray image and ECG analyzes are not very helpful, rapid imaging diagnostic differential diagnosis is required in the absence of specific laboratory biomarkers. Evidence of a dissection lamella that separates two lumens within the aorta is considered evidence of aortic dissection. Transesophageal echocardiography, CT or MRI are more accurate and faster than angiographic imaging. If aortic dissection is suspected, the patient should be transferred immediately to a center with the option of surgical and interventional therapy.
Treatment of Aortic Dissection
There is currently no evidence level A or B for the comparison "drug therapy versus open conventional surgery" for acute type B aortic dissection. The final treatment decision regarding the time and type of aortic surgery remains with the treating doctor. For the treatment of acute type A aortic dissection, the evidence base of the therapy recommendations looks similar (guidelines from the German Society for Thoracic, Cardiac and Vascular Surgery are currently being drawn up). Since endovascular therapy using stent graft implantation is not an option for this location, previous, mostly retrospective examinations referred to the comparison "drug therapy versus open conventional surgery". This work shows a clear advantage of surgical therapy, especially if it is given early after the onset of symptoms, over drug therapy, so that further prospective randomized investigations with this question would not be justifiable.
Medication
Analgesia and blood pressure adjustment to systolic values from 100 to 120 mm Hg can be achieved by morphine application and administration of beta-blockers, in combination with vasodilators or ACE inhibitors. Of course, any contraindications must be taken into account when choosing antihypertensives. Monotherapy is rarely sufficient, so that in the case of massive hypertension, several antihypertensives must be combined.
Surgical treatment
Surgical treatment of type A aortic dissection is intended to prevent rupture or the development of a pericardial tamponade and must be carried out immediately. Sudden aortic valve or coronary insufficiency with secured aortic dissection does not tolerate postponing surgical therapy.
Operations of the ascending aorta - In type A aortic dissection, the primary goal of the operation is to provide the aortic section affected by the tear with a vascular prosthesis or a valve-wearing conduit (vascular prosthesis with a heart valve). If only the ascending aorta is affected, without anuloaortal ectasia, and if the aortic valve is sufficient and not stenosed, a supracoronary replacement can take place. The dissecting wall of the aorta must be refixed. A vascular prosthesis corresponding to the aortic diameter is then positioned above the coronary ostia. If the aortic valve is sclerosed and stenosed, it can be replaced with a biological or mechanical aortic valve. If the aortic valve is stenosed and there is also an ectatic aortic root, a valve-wearing conduit can be positioned. The prosthesis is anchored in the aortic valve annulus, at the level of the two coronary ostia two holes are made in the prosthesis and both coronary ostia are re-implanted in these windowed prosthesis sites.
If the pocket flaps of the aortic valve have lost their ability to adapt due to ectasia of the aortic root and the aortic valve has become insufficient, one should aim for a valve-preserving aortic root reconstruction according to Yacoub or David. These surgical techniques have a low long-term complication rate compared to operations with aortic valve replacement. It is advantageous that the physiological function of the aortic valve is maintained and no oral anticoagulation with its undesirable side effects is necessary.
Yacoub described the "remodeling technique" of the aortic root, in which the aortic wall in the area of the three sinus valsalvae is cut back to the transition of the left ventricle. The resulting defect is then covered by a mirror-image configured Dacron prosthesis. The coronary arteries are reimplanted orthotopically into the prosthesis. According to David, the native aortic valve is first skeletonized. They are re-hung inside a prosthesis placed over the aortic root (“reimplantation technique”). The coronary arteries are also re-implanted orthotopically.
Aortic arch surgery - Most type A aortic dissections affect the ascending aorta and the aortic arch, which may affect the supraaortic vessels. The aortic arch should be explored for further tears. If these are missing, a distal anastomosis between the graft and all aortic layers in the distal ascendant area is sufficient. If there are further tears in the arch, a partial arch or complete arch replacement is recommended. Depending on the extent of the dissection, the aortic arch can be replaced proximally, partially, totally or using the elephant trunk technique. It is often possible to perform the anastomosis at an angle in the arch, so that the head and arm vessels do not have to be connected to the prosthesis separately.
If total arch replacement is necessary, the distal anastomosis is performed in the area of the proximal descending aorta. With total aortic arch replacement, an oval piece is cut out of the prosthesis convexity and the supraaortic vascular outlets are re-implanted as a common island in the prosthesis. If the descending aorta is affected over its entire length, the elephant trunk technique is recommended. In the primary arch replacement, the distal end of the prosthesis is advanced into the descending aorta and floats freely there (Figure 4). During the second procedure (descendent or thoracoabdominal aortic replacement), the distal end of this prosthesis is then connected to another prosthesis.
Treatment of type B aortic dissection
Patients with uncomplicated acute type B aortic dissections have to be monitored intensively. The blood pressure setting is important. Rapid interventional or, in rare cases, surgical treatment can be considered for acute complications of type B aortic dissections. In acute type B aortic dissection, ischemia of the intestinal organs, kidneys or extremities are the most immediate complications.
In the past, fenestration surgery was common, after which the dissection membrane in the infrarenal area of the aorta was partially cut out after laparotomy, so that perfusion between the true and false lumen was achieved again and all aortic vascular outlets were reconnected to the perfusion. The dissection membrane can be perforated interventionally according to the same principle. However, forecast-relevant data is missing for both fenestration techniques.
Endovascular stent graft implantation
Today, endovascular placement of stent grafts is the preferred method of remedying distal malperfusion or other complications, such as impending aortic rupture, for complicated acute type B aortic dissections. Here, a plastic-coated stent is advanced into the area of the tear and covered over a surgical access via the A. femoralis communis. This suddenly improves the perfusion of the true lumen, including the side branches. The goal of this therapy is to remove the compression of the true lumen by the pressurized false lumen, to close the proximal tear and thus to initiate thrombosis of the wrong lumen. In about two thirds of the cases, the dissected aorta can be reconstructed.
Another approach is the prevention of late complications in subacute or chronic type B aortic dissection with the aim of preventing the wrong lumen from forming aneurysm. There is no evidence-based basis for this, so that further randomized prospective studies first have to prove the advantage of stent graft therapy for this indication. In view of this data situation, the "Endovascular Surgery Task Force of the Society of Thoracic Surgeons" made the following treatment recommendation in its consensus paper: "Endovascular stent graft implantation should only be used for subacute or chronic type B aortic dissection High-risk patients are performed. Furthermore, in the endovascular procedure, an open false lumen and a proximal tear (which can be covered with a stent graft) in connection with
- an aortic diameter that is over 5.5 cm or
- an aortic diameter that is more than 1 cm per year has increased or
- therapy-refractory antihypertensive therapy in combination with a collapse of the true lumen or renal malperfusion or
- recurrent back pain or chest pain that has no other cause is present. In contrast, in younger patients with no increased risk, an open surgical procedure for subacute or chronic type B aortic dissections is preferable to endovascular therapy. ”
Endovascular procedures require a specialized team of interventionists and surgeons. With appropriate experience, the 30-day mortality rate can be reduced to below 6%. If the length of the stent graft does not exceed 20 cm, paraplegia occurs in a maximum of 1% of cases with a 1-year survival rate of over 90%.
Aftercare
Long-term therapy after successful initial treatment is based on the understanding of a chronic illness, which in the long term can lead to further vascular complications in the form of progression of the dissection, aneurysm formation or rupture. The diameter of the aorta, biological age, untreated arterial hypertension and a perfused false lumen are risk factors for this. Patients with MFS or EDS in particular are at risk of further vascular complications. Therefore, all patients with aortic dissection must be treated with long-term antihypertensive treatment.
An essential part of pharmacological treatment is an effective beta blockade with the aim of reducing blood pressure to below 120/80 mm Hg. This therapy concept has proven to be useful for prognosis, especially in young patients with MFS. In addition, regular check-ups by means of slice diagnosis (CT or MRI) should be carried out. The background is that a third of all patients who have survived acute aortic dissection experience either disease progression or aortic rupture within five years or require further surgical or interventional treatment. Recommended examination intervals are three and six months and then annual intervals. It is essential to display the entire aorta and to compare the current examination with previous findings. Particular attention should be paid to progressive residual dissection, changes in the aortic diameter, evidence of a covered aortic rupture, newly developed intramural hematomas and the behavior of the anastomoses.
In patients with reimplanted coronaries, ergometric follow-up should be carried out at regular intervals and coronary angiography should be performed if stenosis in the area of the coronary anastomoses is suspected. Patients with reconstructed heart valves should undergo echocardiography annually.
If an aortic diameter of more than 5.5 cm develops, endovascular or open surgical restoration is indicated. The best results are achieved in patients with MFS if the reconstruction of the ascending aorta is already performed openly with a diameter of 4 to 4.5 cm.
