Renal vascular anatomy

Renal vascular anatomy

1. RENAL VASCULAR ANATOMY: SURGICAL CONSIEDERATIONS Dr. Prateek Laddha CMC Ludhiana

2. Body wall • Perirenal fat capsule Renal artery Renal vein Inferior vena cava Aorta • Fibrous capsule • Renal fascia anterior posterior Supportive tissue layers Body of vertebra L 2 Peritoneum Peritoneal cavity (organs removed) Anterior Posterior

3. Aorta Renal artery Segmental artery Interlobar artery Arcuate artery Cortical radiate artery Afferent arteriole Glomerulus (capillaries) Nephron-associated blood vessels Inferior vena cava Renal vein Interlobar vein Arcuate vein Cortical radiate vein Peritubular capillaries and vasa recta Efferent arteriole Path of blood flow through renal blood vessels

4. Cortical radiate vein Cortical radiate artery Arcuate vein Arcuate artery Interlobar vein Interlobar artery Segmental arteries Renal artery Renal vein Renal medulla Renal cortex Frontal section illustrating major blood vessels

5. RENAL VASCULAR ANATOMY The renal pedicle classically consists of a single artery and a single vein that enter the kidney via the renal hilum . The renal arteries arise from the aorta at the level of the intervertebral disk between the L1 and L2 vertebrae where the longer right renal artery passes posterior to the inferior vena cava (IVC). Renal arteries give branches to the adrenal glands, renal pelves , and proximal ureters.

6. Blood supply of the kidney. A and B, Segmental branches of the right renal artery demonstrated by renal angiogram. C, Segmental circulation of the right kidney shown diagrammatically. Note that the posterior segmental artery is usually the first branch of the main renal artery and it extends behind the renal pelvis. a, artery

7. Figure 91.12 Segmental arterial anatomy of the right kidney. (By permission from Walsh PC, Retik AB, Vaughan ED et al ( eds ) 2002 Campbell's Urology, 8th edn . Philadelphia: Saunders.)

8. After entering the hilum, each artery divides into five segmental end arteries that do not anastomose significantly with other segmental arteries. Therefore occlusion or injury to a segmental branch will cause segmental renal infarction. Nevertheless, the area supplied by each segmental artery could be independently surgically resected. The renal artery usually divides to form anterior and posterior divisions.

9. The anterior division supplies roughly the anterior two thirds of the kidney, and the posterior division supplies the posterior one third of the kidney. Typically, the anterior division divides into four anterior segmental branches: apical upper middle and lower

10. The posterior segmental artery represents the first and most constant branch, which separates from the renal artery before it enters the renal hilum. A small apical segmental branch might originate from this posterior branch, but it arises most commonly from the anterior division. The posterior segmental artery from the posterior division passes posterior to the renal pelvis while the others pass anterior to the renal pelvis.

11. If the posterior segmental branch passes anterior to the ureter, UPJO may occur. In 25% to 40% of kidneys, anatomic variations in the renal vasculature have been reported. Supernumerary renal arteries are the most common variation, with reports of up to five arteries, especially on the left side. The main renal artery may manifest early branching after originating from the abdominal aorta and before entering the renal hilum.

12. These perhilar arterial branches should be detected in patients undergoing evaluation for donor nephrectomy. An accessory renal artery may arise from the aorta, between T11 and L4, and terminate in the kidney. Rarely, it may also originate from the iliac arteries or superior mesenteric artery.

13. ACCESSORY RENAL ARTERIES Accessory renal arteries are seen in 25% to 28% of patients and are considered the sole arterial supply to a specific portion of the renal parenchyma, commonly the lower and occasionally the upper pole of the kidney. These accessory renal arteries may contraindicate laparoscopic donor nephrectomy and result in severe bleeding if they are injured during endopyelotomy for UPJO. Multiple renal arteries that arise from the aorta or iliac arteries are frequently seen in horseshoe and pelvic kidneys. In approximately 5% of patients, the main and accessory right renal arteries pass anterior to the IVC.

14. AVASCULAR PLANE OF BRODEL There is a longitudinal avascular plane (line of Brodel ) between the posterior and anterior segmental arteries just posterior to the lateral aspect of the kidney through which incision results in significantly less blood loss. However, this plane may have various locations that necessitate its delineation before incision either by preoperative angiography or intraoperative segmental arterial injection of methylene blue. This has important surgical implications. For example, during percutaneous access into the kidney, posterior calyces along the line of Brodel are preferred. Furthermore, during anatrophic nephrolithotomy (Boyce procedure), an incision is made through this avascular plane.

15. At the renal sinus, each segmental artery branches into lobar arteries, which further subdivide in the renal parenchyma to form interlobar arteries . These interlobar arteries progress peripherally within the cortical columns of Bertin to give the arcuate arteries at the base of the renal pyramids at the corticomedullary junction.

16. Note the close relationship of the interlobar arteries to the infundibuli of minor calyces. Interlobular arteries branch off the arcuate arteries and move radially, where they eventually divide to form the afferent arterioles to the glomeruli. Each afferent arteriole supplies a glomerulus, one of approximately 2 million glomeruli, where urinary filtrate leaves the arterial system and is collected in the glomerular (Bowman) capsule. Blood returns from the glomerulus via the efferent arteriole and continues as either secondary capillary networks around the urinary tubules in the cortex or descends into the renal medulla as the vasa recta.

17. VEINOUS DRAINAGE The renal venous drainage correlates closely with the arterial supply The exception that unlike the arterial supply, has extensive collateral communication through the venous collars around minor calyceal infundibula. Furthermore, the interlobular veins that drain the post-glomerular capillaries also communicate freely with perinephric veins through the subcapsular venous plexus of stellate veins. The interlobular veins progress through the arcuate, inter-lobar, lobar, and segmental veins paralleling their corresponding arteries.

18. Three to five segmental renal veins eventually unite to form the renal vein. Because the venous drainage communicates freely forming extensive collateral venous drainage of the kidney, occlusion of a segmental venous branch has little effect on venous outflow. The right and left renal veins lie anterior to the right and left renal arteries and drain into the IVC. Whereas the right renal vein is 2 to 4 cm long, the left renal vein is 6 to 10 cm. The longer left renal vein receives the left suprarenal (adrenal) vein and the left gonadal (testicular or ovarian) vein.

19. The left renal vein also may receive a lumbar vein, which could be easily avulsed during surgical manipulation of the left renal vein. The left renal vein traverses the acute angle between the superior mesenteric artery anteriorly and the aorta posteriorly. In thin adolescents, the left renal vein may get compressed between the superior mesenteric artery and aorta, causing nutcracker syndrome. In approximately 15% of the patients, supernumerary renal veins are seen and often are retroaortic when present on the left.

20. Accessory renal veins are more common on the right side, and the most common anomaly of the left renal venous system is the circumaortic renal vein, reported in 2% to 16% of patients. The retroaortic renal vein is less commonly seen than the circumaortic vein, in which the left renal vein bifurcates into ventral and dorsal limbs, which encircle the abdominal aorta. In retroaortic renal vein, the single left renal vein courses posterior to the aorta and drains into the lower lumbar segment of the IVC.

21. IMAGING FOR RENAL VASCULAR ANATOMY: Doppler ultrasonography clearly identifies renal arteries at their origin from the abdominal aorta . However, the main renal artery is often difficult to identify at baseline ultrasonography. (CTA) is currently considered the gold standard to assess renal arteries, with 100% sensitivity for identification of renal arteries and veins. The 3D volume-rendered CTA has emerged as a fast, reliable, and noninvasive modality that can reliably and accurately depict the number, size, course, and relationship of the renal vasculature.

22. Arterial branches down to the segmental branches could be identified, but vessels smaller than 2 mm could be missed. Magnetic resonance arteriography uses no ionizing radiation, does not require arterial access, and includes different imaging techniques to visualize renal vasculature. Contrast material can give faster, better resolution and more accurate images without artifacts , inferior mesenteric artery and diaphragm), with occasional additional drainage into the retrocrural nodes or directly into the thoracic duct above the diaphragm.

23. Right renal lymphatic drainage primarily goes into the right interaortocaval and right paracaval lymph nodes (between common iliac vessels and diaphragm), with occasional additional drainage from the right kidney into the retrocrural nodes or the left lateral para-aortic lymph nodes.

24. Vascular Complications Preoperative patient preparation history and physical exam to elicit any signs or symptoms of bleeding dyscrasias work-up as needed by hematology should be performed as an uncorrected coagulopathy is the only absolute contraindication for percutaneous renal surgery Preoperative labs should include a prothrombin time/partial thromboplastin time (PT/PTT),international normalized ratio (INR), complete blood count, and serum electrolytes; and cross-matched blood should be available, depending on the type of case. A preoperative urine culture should be negative.

25. increased risk of hemorrhage are those with cardiac stents who are unable to discontinue their antiplatelet medication prior to surgery The recommendations are as follows: antiplatelet agents, such as acetylsalicylic acid and clopidogrel , should be stopped 10 days prior, warfarin 5 days prior, intravenous heparin 6 h prior, and low molecular weight heparin 24 h prior to surgery.

26. Risk of hemorrhage with renal procedures Percutaneous renal biopsy A recent series reports the incidence of postbiopsy hemorrhage (subcapsular and perinephric) to be lower (38.4%, 28 of 73) when 18G core needle biopsies are performed All hemorrhagic complications were managed conservatively; no embolization or blood products were required in this series.

27. Percutaneous cryotherapy/radiofrequency ablation tumor size directly correlated with incidence of bleeding. Tumors with a median size of 4.2 cm were associated with increased rates of postablation hemorrhage when compared to tumors with a median size of 2.6 cm ( P > .05) When only a single probe is used, the rate of bleeding decreases to 0%. The use of multiple probes increases the degree of renal trauma and, hence, the incidence of bleeding complications

28. Percutaneous nephrolithotomy that balloon dilators could decrease the risk of hemorrhage associated with PCNL. factors associated with blood transfusions post PCNL and reported an association with multiple punctures, renal pelvic perforation, inexperience, preoperative anemia and total blood loss Complications decrease with experience.

29. Management Venous haemorrhage Usually conservative AMPLATZ Sheath Nephrostomy tube 24 Fr . Kaye tamponade balloon catheter Perinephric hematoma triphasic abdominal CT scan to distinguish it from urinary leak transfusion of crystalloids and blood products conservative measures fail, then renal angiography and superselective embolization should be performed in an attempt to identify and embolize the bleeding arterial branches a return to the operating room for open exploration could be warranted

30. Post PCNL Haematuria Before embolization After Embolization

31. Laparoscopic partial nephrectomy The majority of the literature regarding the complications of renal surgery focuses on the comparison of open to laparoscopic techniques. When evaluating the hemorrhage associated with laparoscopic renal surgery, it is important to keep it in perspective, because authors define the term “hemorrhage” in multiple ways. For example, a hemorrhage that requires a blood transfusion differs significantly from a hemorrhage that requires reoperative management or embolization. Patients with immediate hemorrhaging postoperatively were managed conservatively 2% (4 of 200), and delayed hemorrhaging occurred in 4% (8 of 200) of the patient.

32. ROBOTIC PARTIAL NEPHRECTOMY

33. Arterial haemorrhage stabilization with crystalloids and blood products, patients should undergo renal angiography and super-selective embolization The most common findings on angiography are arteriovenous fistulas, pseudoaneurysms , and lacerated renal segmental arteries (vessel cut-off) Grade V renal trauma still requires surgical exploration.

34. Vascular anatomy of the ureteropelvic junction: importance for endopyelotomy Today, endopyelotomy is a common procedure for both primary and secondary UPJO. The risk of injuring a large vessel during endopyelotomy can be greatly reduced or even eliminated if the endourologist understands and keeps in mind the 3D vascular relationships to the UPJ [44, 45, 51]. This section describes the vascular anatomy of the UPJ and this should be used to perform endopyelotomy safely and efficiently.

35. Figure 6.41 (A) Anterior view of a right kidney endocast ( pelviocalyceal system together with the intrarenal arteries) shows a close relationship between the inferior segmental artery and the anterior surface of the ureteropelvic junction (UPJ; arrow). u, ureter. (B) Anterior view of a right kidney endocast ( pelviocalyceal system together with the intrarenal veins) shows a close relationship between a vein draining the lower pole and the UPJ (arrow). RV, renal vein; u, ureter (reproduced from Sampaio and Favorito [44], with permission).

36. Anterior vascular ureteropelvic junction relationshiAps 65% of the endocasts there was a prominent artery, vein, or both vessels in close relationship with theventral surface of the UPJ (Figures 6.41 and 6.42). Among these endocasts , the relationship was with the inferior segmental artery in 45%

37. To protect the arteries from lesion, it has been recommended to examine via intrarenal endoscopy the area to be incised for any arterial pulsation and, if detected, to avoid incising that site.

38. the exact role of crossing vessels in obstruction and the success of endopyelotomy are yet to be determined.

39. Thank You