Isolated pulse effect of the superior mesenteric artery on the left renal vein and their syntopy

Objective: to study the isolated effect of the superior mesenteric artery on pathological processes in the LRV basin from the standpoint of anatomical variants of syntopy and hydrodynamic impact. 
Material and methods. The study was conducted on 100 cadavers. The hemodynamic impact was studied by examining the syntopy of the superior mesenteric artery using mathematical techniques and hemodynamics. 
Results and discussion. During the study of cadaveric material, abnormal syntopy of the left renal vein was observed, affecting hemodynamics. During the period of pre-ejection of blood from the left ventricle of the heart, the time of blood ejection from the left ventricle is about 0.24 sec. In this case, the pulse pressure in the aorta begins to increase at the moment of the beginning of blood ejection from the left ventricle. This pressure impulse causes movement of the arterial wall, and, accordingly, the vein wall by the maximum amplitude of 4.65 mm. The blood velocity under the action of this pressure impulse is approximately 0.0465 m/sec. Since the pulsation pressure is transmitted in the venous blood flow in all directions without change, this pressure coincides with the direction of flow in the vein behind the point of contact of the vein with the artery, and is directed towards the blood flow in front of the point of contact. Therefore, the anterior part of the pressure pulse increases the blood flow velocity behind the point of contact of the vein with the aorta by the value of V/2 (23.25 mm/sec) in the layer adjacent to the surface of the vein, and the posterior part of the pulse slows down the blood flow in front of the point of contact by the same value. Such distribution of pressures and blood flow velocities in the vein partially slows down the flow in the vein, and the pressure pulse in the artery, being transmitted to the venous blood flow, partially blocks its lumen. The pressure pulsation in the artery, being transmitted to the venous blood flow, increases the blood flow velocity behind the point of contact of the vein with the aorta by the value of 2.225 cm/sec and, thereby, increases the average velocity of blood movement in the vein. This pulsation results in a local increase in pressure before the contact zone by approximately 1.15 Pa at the peak of the pulsation wave in the fluid layer adjacent to the vein surface with a gradual decrease in pressure with distance from the vessel center. 
Conclusions. A group of causes for the syntopy of the superior mesenteric artery and left renal vein was discovered, causing difficulty in venous outflow and the development of hypertension in the left renal vein basin. The resulting distribution of pressures and blood flow velocities in the vein partially inhibits the flow in the vein at the moment of pressure impulse passage in the artery.

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