Visceral aortic artery ultrasound

Unpaired visceral arteries

As practical activity has shown, color Doppler scanning has high information content in assessing the condition of the superior mesenteric artery, celiac trunk, hepatic (PA) and splenic artery (SA). This creates prerequisites for expanding methodological capabilities and, in particular, studying the issue of ultrasound anatomy of extra- and intraorganic vessels of the spleen.

The technology of studying the splenic artery and vein in the color Doppler and/or EDC mode in the area of the splenic hilum involves oblique scanning in the area of the left hypochondrium with the patient lying on his back, through the intercostal spaces with the patient lying on his right side or from the back. When performing an ultrasound examination, it is necessary to obtain an image of the spleen along the long axis of the organ, the hilum of the spleen and splenic vessels. The splenic artery and vein are located next to each other, with the vein lying slightly in front of the artery. Before reaching the hilum of the spleen, the SA trunk divides into two, less often - into three branches. These are the branches of the first-order splenic artery, or zonal arteries.

Theoretically, the ultrasound image of the spleen along its long axis is divided at the level of the hilum into two halves - upper and lower. The anatomical course of one first-order artery is directed toward the upper half of the spleen, the second artery - toward the lower half. Tracing the anatomical course of the first-order branches in the distal direction, it is visible how these vessels reach the parenchyma of the spleen. In the parenchyma of the organ, each first-order branch is divided into two branches - segmental arteries. In turn, each segmental artery is divided into two branches, etc. The division of the intraorgan branches of the splenic artery is mainly sequential dichotomous. Of the two segmental arteries in the upper half of the spleen, a. polaris superior is located laterally, a. terminalis superior - medially. Similarly, in the lower half of the spleen - a. polaris inferior and - a. terminalis inferior. A. terminalis media is located in the parenchyma at the level of the hilum of the spleen. A qualitative assessment of the angioarchitecture of the spleen parenchyma indicates that most of the vessels are located and branch in close proximity to the hilum of the spleen, to the inner and anterior surface of the spleen, with small branches directed toward the outer surface of the spleen.

The zonal extraorgan vessels can serve as a reference point for determining the vascular zones of the spleen. The anatomical distribution of segmental arteries underlies the segmental division of the spleen. V.P. Shmelev and N.S. Korotkevich consider a zone to be an area fed by an arterial branch of the first order. Accordingly, there can be 2-3 zones of the spleen, the shape of which resembles a 3-4-sided pyramid. A segment is considered to be a morphologically isolated area of organ tissue fed by an arterial branch of the second order. The number of segments depends on the anatomical variation in the division of the first order branches and ranges from 2 to 5. According to A.D. Khrustalev, the main trunk of the splenic artery in 66.6% of cases is divided into two main branches, in 15.9% - into three main branches, and in other cases there may be more branches. According to our data, when studying the ultrasound anatomy of the splenic artery in 15 practically healthy individuals aged 25 to 40 years, the splenic artery was divided into 2 zonal arteries in 73.3% of cases, in 3-26.7% of observations. Each zonal branch in the splenic parenchyma was divided into 2 segmental arteries. The diameter of the splenic artery was 4.6-5.7 mm, the peak systolic velocity (PSV) was 60-80 cm/s, the average velocity was 18-25 cm/s. The diameter of the zonal branches in the color Doppler and/or EDC mode is 3-4 mm, PSS is 30-40 cm/s, segmental - 1.5-2 mm, PSS 20-30 cm/s, respectively.

The study of hematological and immunological indices after splenectomy and organ-preserving surgeries allowed to demonstrate the advantage of conservation surgery. The study of ultrasound anatomy of zonal and segmental branches of the splenic artery has important practical significance. Knowledge of the principles of distribution of intraorgan vessels of the spleen enables the surgeon to choose the most acceptable and anatomically sound method of conservation surgery in case of spleen damage.

Occlusive lesions of visceral arteries have characteristic features. The process extends to visceral arteries for 1-2 cm from the mouth, in non-specific aortoarteritis - in the form of a hypertrophied wall, in atherosclerosis - a locally located plaque is determined, which can move from the wall of the aorta. The inferior mesenteric artery is rarely involved in the process in non-specific aortoarteritis and usually participates in the compensation of blood flow.

Regardless of the cause leading to narrowing of the arterial lumen, with stenosis of more than 60%, a local increase in the LBFV is observed in combination with changes in the spectral characteristics of the blood flow, which acquires a turbulent character, which is confirmed by the data of the analysis of the spectrum of the Doppler frequency shift and a change in the staining of the vessel lumen in the color Doppler mode. With stenosis of 70% or more in the SMA, the systolic velocity is 275 cm / s or more, diastolic - 45 cm / s or more, in the celiac trunk - 200 cm / s and 55 cm / s or more, respectively.

In case of occlusion of visceral arteries, the lumen of the vessel is not stained and the LBFV is not recorded. In case of occlusion of the celiac trunk, reverse blood flow (retrograde) can be recorded in the gastroduodenal or common hepatic arteries. The sensitivity of the CDS method in diagnosing stenosis of 50% or more or occlusion of the superior mesenteric artery is 89-100%, specificity is 91-96%, for the celiac trunk - 87-93% and 80-100%, respectively. In case of hemodynamically insignificant stenosis, the information content of the Doppler frequency shift spectrum is significantly reduced. The most difficult diagnostics are hemodynamically insignificant changes in nonspecific aortoarteritis, in particular, it is difficult to assess the state of the wall. We have introduced into clinical practice a method of three-dimensional reconstruction of unpaired visceral arteries, which has expanded the range of diagnostic capabilities of ultrasound diagnostics.

The 3D reconstruction program includes examinations in B-mode, ultrasound angiography mode, and a combination of B-mode and ultrasound angiography. As we gain experience in examining this group of patients, we believe that the results of the B-mode examination are more informative. Due to the transparency of the image of the vessel wall and lumen, structural features and the wall contour are recorded more clearly. A comparison of the capabilities of color Doppler scanning and 3D reconstruction showed that 3D reconstruction is more informative in determining changes in wall echogenicity. Qualitative analysis of the 3D image allows us to estimate the wall thickness. However, it should be noted that the 3D reconstruction program currently used does not allow for a quantitative assessment of the structures under study, nor does it provide information on the state of hemodynamics. Consequently, these two methods complement each other in diagnosing changes characteristic of nonspecific aortoarteritis, which gives grounds to propose them for complex use. An indication for three-dimensional reconstruction of visceral arteries is the presence of type II or III lesions of the thoracoabdominal aorta in nonspecific aortoarteritis.

One of the causes of hemodynamic impairment in the celiac trunk (CT) is extravasal compression caused by compression of the median arcuate ligament of the diaphragm. The hemodynamic criteria for significant CT compression are: angular deformation of the artery in the cranial direction; an increase in systolic velocity by 80.2 ± 7.5% and diastolic by 113.2 ± 6.7%; a decrease in the level of peripheral resistance, confirmed by a decrease in the pulsation index (PI) by 60.4 ± 5.5% and peripheral resistance index (PRI) by 29.1 ± 3.5%; a decrease in blood flow velocity and peripheral resistance indices in the splenic artery (systolic - by 49.8 ± 8.6%, PI - by 57.3 ± 5.4%, PRI - by 31.3 ± 3.1%.

Abdominal diseases may cause hemodynamic disturbances such as local or diffuse changes in the visceral arteries and their branches. Thus, in case of extravasal compression (EVC) or invasion of the celiac trunk, hepatic artery by enlarged lymph nodes, liver and pancreas masses with a decrease in the vessel lumen by more than 60%, local changes in blood flow are recorded. According to our data, in cholangiocarcinoma, extravasal compression of the hepatic artery was diagnosed in 33% of cases, which is probably due to the infiltrating nature of tumor growth. In patients with hepatocellular carcinoma, the SN and PA were compressed in 21% of cases, and the SMA in 7% of cases. Simultaneous compression of the SN and PA was noted in 14% of cases. Of 55 patients with secondary liver tumors, hemodynamically significant celiac trunk ectopic vasculitis was diagnosed in 1.8% of cases, and the proper hepatic artery (PHA) ectopic vasculitis was diagnosed in 4.6% of cases. Invasion of the PHA branches was noted in 4.6% of cases. In pancreatic cancer, the superior mesenteric artery, SN, and its branches are involved in the process at late stages of the disease. Signs of ECT were detected in 39% of cases, thrombosis or arterial invasion ectopic vasculitis was detected in 9.3% of cases.

The presence of volumetric formations of abdominal organs or diseases of inflammatory genesis contributes to a diffuse increase in the blood flow velocity in the artery, which is directly involved in the blood supply of this organ. Thus, during the acute phase of hepatitis, an increase in systolic and diastolic blood flow velocity in the PA was recorded. When examining 63 patients with ulcerative colitis, Crohn's disease during an exacerbation of the process, an increase in systolic and diastolic blood flow velocity in the IBA was noted in combination with a decrease in the IPS. During the remission period, hemodynamic parameters normalized. According to our data, in hepatocellular cancer, metastatic liver damage, a statistically significant increase in the diameter values and an increase in the blood flow velocity in the celiac trunk and hepatic artery are recorded.