Normal value of renal artery blood flow velocity

The renal artery blood flow velocity is the main indicator of aortic blood flow. Its normal value is 34%, so we should correctly identify the normal value of renal artery blood flow velocity. The kidneys' main function is to allow us to process viruses, and the liver can process the inhalation of toxic substances. Regarding the understanding of what is considered normal renal artery blood flow velocity, it is recommended that you read more about the content introduced in the following article to increase our understanding.

The renal arteries are a pair of relatively large branches of the abdominal aorta. They originate from the lateral wall of the aorta at the 1st to 2nd lumbar vertebral plane, run horizontally outward, and enter the renal hilum behind the renal vein. The abdominal aorta is located on the left side of the body midline, so the right renal artery is slightly longer than the left renal artery. The right renal artery is adjacent to the inferior vena cava, pancreatic head and descending duodenum in front; the left renal artery is adjacent to the pancreatic body, splenic vein and inferior mesenteric vein in front. Before the renal artery reaches the renal hilum, it branches out into the inferior adrenal artery, which runs upward to the adrenal gland; in addition, it also branches out into the ureter. Most renal arteries first divide into anterior and posterior branches (59.1%) or superior and inferior branches (34.3%) near the renal hilum; each branch then branches into the renal parenchyma and is distributed in a certain area without anastomosis between each other, which are called segmental renal arteries.

The inner diameter of the renal artery is 0.5-0.7cm. The spectrum shows a rapid rise in the systolic phase, a slow descending branch, and positive blood flow in the diastolic phase, which occupies the entire diastolic phase. The peak velocity is 60-120cm/s, and RI=0.5-0.7.

Each renal artery usually has one branch (85.80%), but may also have two branches (12.57%). Three branches are extremely rare, accounting for about 1.48%, and four or five branches are even rarer. In addition to entering the kidney from the renal hilum, sometimes 1 to 5 renal arteries and their branches directly penetrate the upper end (57.35%) or lower end (13.79%) of the kidney without passing through the renal hilum, or enter the kidney through the front and back of the kidney. These are called accessory renal arteries or aberrant renal arteries, and their occurrence rate can be as high as 41.33%. This should be of concern to those performing renal surgery.

Nutrition and functional blood vessels of the kidney. The renal artery originates from the abdomen of the aorta, enters the kidney from the renal hilum, divides into several interlobar arteries in the renal sinus, passes through the renal columns, forms arcuate arteries at the base of the renal pyramid, and the arcuate arteries send out radial branches, the interlobular arteries enter the cortical labyrinth, and the interlobular arteries send out afferent arterioles to the renal lobules on both sides along the way. Each afferent artery divides into several small branches in the renal body to form a glomerulus. The glomeruli are then assembled into afferent arterioles, which leave the renal corpuscle and form a capillary network that is distributed on the renal tubules in the cortex and medulla, collecting water and nutrients reabsorbed from the renal tubules. Later, the capillaries gradually gather into interlobular veins, arcuate veins, and interlobar veins parallel to the arteries, and finally flow into the renal vein and exit the kidney through the renal hilum.

The kidneys have a large blood flow, with an average of about 1200 ml of blood flowing through both kidneys per minute. The blood flow in different areas of the kidney is different. The cortex is richly supplied with blood and the flow rate is fast; the medulla is poorly supplied with blood, accounting for only 1/10 of the renal blood flow, and the flow rate is also slow. Under strong stimulation (severe contusion, limb crush, etc.) or stress, it can reflexively cause renal vasospasm (usually interlobular arteries) and ischemia, causing blood circulation disorders in the renal corpuscles and afferent arterioles. As a result, the renal tubules are insufficiently supplied with blood, especially the renal cortex is ischemic, which turns gray, followed by medullary ischemia, often causing anuria or shock, the so-called "contusion syndrome." In severe cases, it can cause renal tissue necrosis.

Renal artery embolism is a blockage of the main renal artery or one of its branches caused by a dislodged embolus. Most emboli come from growths in the heart or aorta, and rarely are emboli formed by tumor cell clusters or fat. It can occur unilaterally or bilaterally. Renal ischemia or infarction after embolization. Clinical manifestations include low back pain, fever, hematuria or oliguria. Percussion pain in the affected kidney area. The levels of transaminase, lactate dehydrogenase, etc. in blood and urine are elevated. It is also prone to embolism in other parts of the body, such as splenic and retinal artery embolism. Radionuclide renal vascular scanning and color Doppler are of diagnostic value. In the early stage, thrombolytic therapy or surgical removal of the embolus can be tried. If kidney failure occurs, dialysis or kidney transplantation is done. Failure to eliminate emboli can lead to renovascular hypertension.