Splenic artery aneurysm.

Pathologic dilation (Greek: aneurysma) with the formation of a bulging area in the vascular wall of the splenic artery (arteria splenica), a visceral arterial vessel that carries blood to the spleen, pancreas, and part of the stomach, is defined as a splenic artery aneurysm. [1]

Epidemiology

According to some data, splenic artery aneurysm occurs in about 0.1 -1% of the adult population, but it accounts for at least 60% of all visceral artery aneurysms. And among intra-abdominal aneurysms, abnormal dilation of the splenic artery ranks third in prevalence after aortic and iliac artery aneurysms.

In women, splenic artery aneurysms are 3-5 times more common than in men.

Causes of the splenic artery aneurysms.

Splenic vascular aneurysms are a serious problem of the circulatory system. The main causes of this potentially life-threatening condition are associated with diseases and pathologies such as:

• affecting the walls of blood vessels atherosclerosis (which occurs when blood cholesterol levels are high);
• elevated blood pressure - systemic hypertension;
• high resistance in the portal vein system - portal hypertension, which can result from hepatitis and other infections, cirrhosis, sarcoidosis and a variety of other pathologies;
• Splenomegaly (increased size of the spleen);
• chronic pancreatitis (inflammation of the pancreas);
• abdominal trauma;
• Autoimmune collagenoses (collagen vascular diseases), including systemic lupus erythematosus, polyarteritis nodosa, systemic scleroderma;
• Fibromuscular dysplasia (vascular dysplasia or medial fibrodysplasia);
• Immune response-mediated vascular inflammation - vasculitis;
• A vascular form of genetically determined Ehlers-Danlos syndrome.

Risk factors

The main risk factors for the development of splenic artery aneurysm experts consider high blood pressure, pregnancy (late term), systemic hemodynamic disorders, connective tissue pathologies, advanced age, liver transplantation. [2]

Pathogenesis

Arterial walls have three sheaths (or layers): outer (adventitia), middle (tunica media) and inner (tunica intima). Read more in the article - Arteries

The features of the splenic artery are its length (it is the longest branch of the splenic artery), tortuosity - with loops and bends, as well as the pulsating character of blood flow, provoking excessive stretching of the vessel.

The pathogenesis of limited dilatation, stretching and bulging of part of the arterial wall is due to its weakening - thinning, decreased strength and deformation - due to structural changes.

Aneurysm formation in atherosclerosis is associated with dysfunction of the endothelium forming tunica intima.

In the case of vascular dysplasia, an aneurysm is formed as a result of pathologic changes in the vessel wall, which has no outer and middle layers and consists of endothelium and subendothelial connective tissue.

In aneurysms due to portal hypertension, the pathology is caused by a disturbance of visceral hemodynamics with the development of systemic hyperdynamic circulation and increased vascular resistance.

Finding the mechanism of splenic artery aneurysm formation in pregnancy, the researchers concluded that it lies in hemodynamic and hormonal changes in late gestation. First of all, it is an increase in blood flow in the splenic artery, because by the last trimester of pregnancy, the CVC (circulating blood volume) increases by an average of 35-45%. Secondly, it is the effect on the vessel walls of the peptide hormone relaxin, produced during pregnancy to increase the elasticity of the cartilage of the pubic symphysis. It is now known for certain that this hormone affects the elastic properties of the systemic vascular network - increasing the stretchability of arterial walls. [3]

Symptoms of the splenic artery aneurysms.

Splenic artery aneurysms are usually asymptomatic and are usually an incidental finding on ultrasound examinations.

But the pathology can manifest itself, and its symptoms include pain of varying intensity in the epigastric region or in the left upper quadrant of the abdomen, often radiating to the left shoulder.

The size of the aneurysm can range from 2 to 9 cm, but it usually does not exceed 3 cm. Usually the aneurysm in a given blood vessel is located in the middle or distal part, and this, according to its localization, is diagnosed as an aneurysm of the middle third of the splenic artery or an aneurysm of the distal part of the splenic artery (near its bifurcation to the terminal branches).

In most cases, this is a saccular aneurysm of the splenic artery, which have a spherical shape of varying diameter and is characterized by the appearance in a limited area of the vessel bulge on the side of the vessel, in shape resembling a sac (which may be partially or completely filled with thrombus).

Often, when calcium salts accumulate in the vessel wall, peripheral calcification is found and a calcified or calcified or calcified splenic artery aneurysm is defined. [4]

Complications and consequences

Complications and consequences of this pathology are rupture of splenic artery aneurysm (in 7-10% of cases, and in symptomatic patients - 76-83% of cases) with the development of life-threatening intraperitoneal hemorrhage.

The rupture is manifested by acute diffuse abdominal pain (similar to acute abdomen) and hypovolemic shock. The overall mortality rate is estimated at 25 36% of cases.

Most ruptures occur during pregnancy (in the last three months), with maternal mortality reaching 70-75% and fetal intrauterine mortality approaching 100%.

Diagnostics of the splenic artery aneurysms.

Diagnosis requires examination of the patient, a detailed history and clinical examination.

Blood tests are taken, including general, biochemical and for serum endothelial antibodies.

The main role is played by instrumental diagnostics: ultrasound of arteries of internal abdominal organs; CT angiography with contrast, contrast angiography, ultrasound vascular Doppler.

The splenic artery is defined as aneurysmal when there is focal dilation in its diameter by more than 50% compared with the normal vessel diameter (0.43-0.49 cm). [5]

Differential diagnosis

Differential diagnosis includes aneurysm of abdominal, mesenteric, or hepatic artery, pancreatic pseudocysts, and calcified hematoma of the left adrenal gland.

Treatment of the splenic artery aneurysms.

If an aneurysm is detected accidentally asymptomatic, outpatient follow-up with monitoring - periodic visualization of the splenic artery - is performed. If the aneurysm is larger than 2 cm, further enlarged or symptomatic, treatment is necessary. [6]

This is a surgical treatment, the choice of which depends on the shape, size and localization of the aneurysm, as well as the patient's condition. However, regardless of the size of the aneurysm, intervention may be required in the presence of liver cirrhosis. [7]

Traditional surgery for splenic artery aneurysm has three options: excision of the aneurysm and stitching of its edges (aneurysmorrhaphy), ligation (ligation) with arterial reconstruction, and revascularization with splenectomy (or without it).

In addition to open surgery may be performed: minimally invasive laparoscopic aneurysmectomy with splenic artery anastomosis (with spleen preservation), stent implantation in the neck of the aneurysm and transcatheter endovascular embolization.

Prevention

The main prevention is early recognition of splenic artery aneurysms - in the initial (asymptomatic) stages - and timely intervention.

Obstetricians and gynecologists supervising the pregnancy should be particularly vigilant.

Forecast

The prognosis of splenic artery aneurysm cannot be considered completely favorable, given the high probability of its rupture and the frequency of lethal outcomes of this complication.