Arterial aneurysm is defined as dilatation of arterial diameter by more than 50 % of its normal diameter, this happens in the locations of weakened vascular wall. Aneurysm can be present in any part of human body, but there are several locations with typical higher presence of aneurysms. One of these locations is abdominal aorta, where aneurysm can be found in up to 8 % of people older than 65 years. Another typical locations are thoracic aorta, popliteal artery, which is often coupled by abdominal aortic aneurysm, or intracranial aneurysms, present in lower age and visceral aneurysms, most commonly aneurysm of spleen artery. Beside typical aneurysm formed by weakened but complete arterial wall there can be another condition called pseudoaneurysms. This pseudoaneurysm develops after a trauma or defect in vascular wall causing bleeding into surrounding tissues. Cavity formed by bleeding can demarcate and thus a space with blood flow connected to the original artery is formed. Main difference between aneurysm and pseudoaneurysm is that border of pseudoaneurysm is not formed by vascular wall but by surrounding tissues.

This is a picture of 3D reconstruction of abdominal aortic aneurysm from CT scans and it shows overall morphology of this aneurysm before the diagnostic decision is made.

3D reconstruction from CT scans (archive of 2nd Department of Surgery)

Etiology and risk factor for aneurysms are yet well know at the time. As for any other disease there is a genetic risk. In a case of aneurysm presence in direct relative a patient has much higher risk of aneurysm development than normal population. There is also a connection between aneurysms and genetic disorders of connective tissue like Marfan or Ehlers-Danlos syndromes. Another well confirmed risk factors for aneurysms development are hypertension (higher blood pressure logically leads to higher risk or artery dilatation) and smoking causing a chronical inflammation in vascular wall. Atherosclerosis causes mostly ischemic problems but it can be also connected with aneurysm development. Another risk factors are not so common but still you must keep them in mind especially in case of post-traumatic aneurysms (e.g. car accident or stabbing trauma) and infectious aneurysms, so called mycotic aneurysms (this name is backed up by the shape of the aneurysm rather than its cause). Infectious aneurysms were big problem in the past, when there was much higher incidence of specific inflammations like syphilis and tuberculosis. At the time the most common germ causing infectious aneurysms is salmonella.

There are two basic factors needed to transform a healthy artery into an aneurysm – chronic inflammation and higher blood pressure. Above mentioned risk factors lead to the chronic inflammation in vascular wall with macrophage infiltration and vascular wall remodeling decreasing the amount of elastic fibers and decreasing the vessel resistance to blood pressure. Due to turbulent flow there can be intraluminal thrombus formed in aneurysms (blood cloth on the inner side of the vascular wall) which can cause a vascular ischemia and further inflammation. Process sis finished by hypertension by higher blood pressure dilatating an artery in the locations of weekend wall. Hypertension is also a main risk factor for aneurysm rupture, in cases of sudden sever blood pressure increase the vascular wall can rupture and cause a life threatening bleeding.

The insidious thing about aneurysms is a fact that in vast majority of cases there are very poor or none symptoms. If the aneurysm starts to cause some subjective or objective problems i tis called symptomatic aneurysm which are connected with much higher risk of complications. One of these symptoms can be a pain, e.g. abdominal and lumbar pain caused by AAA or headache caused by intracranial aneurysms. There can be also a compression of surrounding tissues and organs in a case of larger aneurysms. These symptoms can be digestive problems, vertigo and headache, there can be also a lower limb swelling cause by popliteal aneurysm compressing a popliteal vein. We also mentioned that intraluminal thrombus can be formed in the lumen of aneurysm. This thrombus can cause peripheral embolization with all ischemic consequences. Equally there can be a complete aneurysm occlusion again causing an ischemic symptoms, this situation is typical for popliteal aneurysm.

On this CT image well documented complete thrombosis of left popliteal aneurysm, which caused an acute ischemia of left leg leading to urgent aneurysm resection and bypass implantation. There is also smaller right popliteal aneurysm with intraluminal thrombus. Interesting fact – this patient went up with resection of right popliteal aneurysm and AAA.

Thrombosis of left popliteal aneurysm (archive of 2nd Department of Surgery)

Any aneurysm rupture causes life threatening bleeding and sever risk of permanent disability or death of the patient. I tis one of the most severe conditions not only in cardiovascular surgery but in neurosurgery as well. Mortality of aneurysm rupture is immense, mainly in case of intracranial aneurysm, where there is not such a risk of bleeding to death but more importantly there is a vast destruction of brain tissue and in the case of aortic aneurysm where is the highest risk of bleeding all the blood volume into abdominal or thoracic cavity. Because aneurysm are in vast majority of cases asymptomatic the rupture is often the first and also fatal sign of its presence. Most of the patients die immediately after the rupture in form of a sudden death. If the patient survives the first rupture and gets into relatively stabilized condition he/she can be transported into specialized center. Even thou the mortality is still around 50 %. If the patient survives rupture of aortic or popliteal aneurysm and consequent surgery and hospitalization, than there is a good chance of returning the patient to normal life. On the other hand after intracranial aneurysm rupture the prognosis is much worse and even after the rupture survival up to 2/3 of the patients end up with severe disability.

There is an AAA rupture on the right side of the aorta with hematoma in the right part of retroperitoneal space.

AAA rupture with hematoma in retroperitoneal space (archive of 2nd Department of Surgery)

Basic approach to prevent aneurysm complications is to timely diagnose a treat the aneurysm. The main problem is to even keep the possibility of aneurysm presence in mind during the diagnostic process because of the poor symptomatology. The most useful information from patients medical history is a presence of an aneurysm in some relative and the presence of risk factors – hypertension, smoking and trauma. This situation regarding physical examination is different, in some cases like intracranial and visceral aneurysms there is no information we can get from this examination, but in other cases like popliteal or large AAA we are able to set the diagnose fairly precise by just our touch. Golden standard of aneurysm diagnostics are imaging methods. Not only in cases of aneurysm suspicion but also in cases when aneurysm is found accidentally during the examination performed because of different condition (e.g. AAA during kidney ultrasound). Ultrasound examination is fast, cheap and simple method and in the case of aneurysm suspicion this should bet he first examination to confirm aneurysm presence. Ultrasound examination has of course its limitations, it can´t describe the anatomical proportion precisely and in the case of intracranial aneurysms its applicability is minimal. Nevertheless it is very effective examination and it is also ideal method for screening of aneurysm presence in risk population (there is no such screening in Czech Republic). CT and MR angiography are the best methods which can precisely describe the proportion and location of aneurysm as well as its morphology and are ideal methods for intervention planning. CT is available non-stop in most hospitals thus it can be used even in situations of rupture suspicion. The use of classical angiography is limited because only the lumen with contrast agent is displayed, but this is usually significantly limited by thrombus and thus it can cause undervaluation of aneurysm diameter. On the other hand angiography has it irreplaceable position during endovascular interventions during aneurysm treatment.

In the situation when an aneurysm is identified and an intervention is indicated we have two basic ways how to approach the situation. First is the classical surgical approach with aneurysm resection and bypass implantation and the second one the modern approach of endovascular intervention with aneurysm exclusion from blood flow. Endovascular methods are clipping, fulfilling the aneurysm with coils, so called coiling and stentgraft implantation.

Classic open surgical resection and implantation of dacron vascular prosthesis. Lower image showing proximal anastomosis (on the left side) and branches of the prosthesis leading further to the groins (on the right side).

(archive of 2nd Department of Surgery)

Schematic picture of endovascular methods – coiling of aneurysm sack upper left, on the right clipping of aneurysm neck, stentgraft implantation lower right and combination of coiling and stentgraft implantation on the left.

Angiographic images during haptic artery aneurysm endovascular repair, aneurysm is visible on the left picture. On the right picture is final state after coiling leading to thrombosis of aneurysm sack and thus its exclusion from the blood flow.

Coiling of a.hepatica aneurysm (archive of 2nd Department of Surgery)

Another angiographic images of AAA treatment with EVAR method, during this method a bifurcation stentgraft is implanted in abdominal aorta and iliac arteries leading to exclusion of aneurysm wall from blood flow and thus preventing the blood pressure effect on weakened wall.

EVAR (archive of 2nd Department of Surgery)

The most common arterial aneurysm is abdominal aortic aneurysm (AAA) and we will now learn some more details about this condition. The decision for intervention or surgery is directed by several rules, if we identify symptomatic or fast-growing aneurysm (meaning enlargement of aneurysm diameter more than 5 mm per 6 months) there is an intervention indicated not regarding the maximal diameter. If we identify asymptomatic aneurysm the next course of action is directed by its maximal diameter. If this diameter is less than 5,5 cm the patient is followed by CT angiography or ultrasound, if the diameter is larger than 5,5 cm intervention is indicated. This threshold value of 5,5 cm was set by an empiric experience – risk of rupture of such aneurysm is 3-5 % per year what is the same as is a mortality of elective aneurysm surgery. Thus, if the diameter is larger than the risk of rupture is higher than the risk of surgery

Keeping in mind the possibility of AAA presence is the key diagnostic feature, mainly in the risk population what is males (in male gender the risk of AAA presence is 4 times higher), older than 65 years with hypertension and smoking. In such a case the risk of AAA presence is up to 10 %! As it was mentioned above the easiest way of examination is palpation of abdomen, what can be done by general practitioner during preventive visits. Using this technique, we can feel a pulsating resistance located left from umbilicus. If the aneurysm presence is suspicious, we will send patient for ultrasound examination to confirm the diagnose. If the AAA presence is confirmed by ultrasound patient should also have a CT angiography which can describe the precise diameter and morphology of AAA, with this information patient should be send to vascular-surgery center.

On the upper picture we can see a CT image of huge AAA with diameter 12 cm, this aneurysm can be also easily examined by palpation. On the lower picture is an AAA of another patient found during ultrasound examination, its diameter is 4,5 cm.

(archive of 2nd Department of Surgery)

In case of slim patient sometimes we can even see a pulsation in umbilicus area and during palpation we can feel a pulsating resistance in form of an „pulsating egg“.

(archive of 2nd Department of Surgery)

Besides the classic diagnostic methods there is also an effort to find new sophisticated methods of AAA rupture risk predictions in last two decades. Among these methods there is a method of vascular wall stress assessment using so called finite element method, which is capable of very precise identification of risk spots in aneurysm wall and calculate its stress, what can be used for rupture risk assessment much more precise than would be assessed based only on aneurysm´s maximal diameter.

(archive of 2nd Department of Surgery and Brno University of Technology) GAČR Grant GA13-16304S

Essence of the surgical treatment of AAA is its removal (resection) and replacement of vessel by bypass made of vascular prosthesis (or in some cases made of patients own veins of transplanted aorta). Since this is a very invasive and vast surgical procedure, a careful consideration is needed before each surgery. Based not only on above mentioned criteria but also based on patients overall status when severe comorbidities could significantly increase the risk of surgery. In cases of high risk patients endovascular treatment should be considered since i tis less invasive and less risky. There is also a possibility of mini-invasive surgical procedures such as laparoscopy or robotic surgery.

The main already mentioned advantage of endovascular treatment (EVAR) is its mini-invasive approach. On the other hand even this kind or treatment has its limits and risks. Patient must be morphologically suitable for this kind of treatment, this means no severe tortuosity of iliac arteries which are used as access for implantation and an aneurysm neck must not by very angled, i tis a location between renal arteries and aneurysm sack. Disadvantage is also much higher price of stentgraft, the prize of dacron prosthesis is 10 thousands CZK but the price of stentgraft is 250 thousands CZK. In western countries the EVAR is a leading procedure over open surgery, in our country the indication is more strict and open surgery is still dominant procedure. The main clinical disadvantage of EVAR is much higher number of CT examinations needed after the implantation and also an often need for re-intervention in case of so called endoleak, what is a blood leak between stentgraft body and aneurysm wall or between the parts of stentgraft itself. During the last year there are finally more realistic reports of long-term EVAR data showing not only its better performance in short-term compared to open resection, but also worse long-term outcome with a need for many re-interventions and overload of heart caused by tough stentgraft skeleton. Both EVAR and open resection have their advantages and limitations and decision which to use should be driven by common sense not by financial motivation or restriction, that the indication would be chosen as the best for each patient.

Both open resection and EVAR have a certain percentage of complications of course. In the case of open resection the most important is peri-operative bleeding and post-operative paralytic ileus (what is common reaction of the body to abdominal surgery rather than a complication and it passes out in few days). More severe complications are infection of surgical site, mostly in the groins and less common but very severe is infection of prosthetic graft. This situation can lead to a rupture of suture or graft body and life-threatening bleeding. Similar situation is in a case of aorto-duodenal fistula. Both this complications require immediate surgery, graft explantation and its replacement by autologous graft. The most common complication after EVAR is an endoleak, we can distinguish 5 types of endoleak, most of theme requiring frequent re-interventions. There can be also any other mechanical complication like stentgraft cranking or rupture and infectious complications as well requiring the same approach as in case of prosthetic graft infection.

Krajíček Milan, Peregrin Jan H., Roček Miloslav, Šebesta Pavel a kolektiv, Grada Publishing a.s., 1. 1. 2007 - Počet stran: 436.

ISBN 8024706075, 9788024706078

European Society for Vascular Surgery (ESVS) 2019 Clinical Practice Guidelines on the Management of Abdominal Aorto-iliac Artery Aneurysms

Aneurysm – Wikipedia