|Year : 2020 | Volume
| Issue : 4 | Page : 196-200
A computed tomography angiography study to correlate main renal artery diameter with presence of accessory renal artery in healthy live kidney donors
Alka Nagar1, Navbir Pasricha2, Eti Sthapak2, Deshraj Gurjar3, Hira Lal4
1 Department of Anatomy, GSVM Medical College, Kanpur, Uttar Pradesh, India
2 Department of Anatomy, Dr. RML Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
3 Department of Nephrology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
4 Department of Radiology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
|Date of Submission||13-Mar-2020|
|Date of Acceptance||19-Oct-2020|
|Date of Web Publication||29-Dec-2020|
Dr. Navbir Pasricha
Flat No. 705, Faculty Residential Apartments, Dr. RML Institute of Medical, Sciences, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: The chosen technique of surgery during nephrectomy can be influenced by the sudden discovery of an aberrant source of blood supply to the kidney. Thus, a prospective study was undertaken to investigate the relationship between the diameter of the main renal artery and the presence of an accessory renal artery by computed tomography (CT)-angiography. Material and Methods: The study was conducted on 115 healthy kidney donors who presented to the department of nephrology and radiology for voluntary kidney donation. All CT examinations were performed on a 64-slice CT scanner in the arterial phase. The number of the renal arteries supplying each kidney was evaluated and their diameters were measured. Results: Eighty-six of the right side and 88 of the left side of the 115 kidneys donors had a single renal artery whereas 29 had one or more accessory renal artery (aRA) on the right side and 27 had one or more aRA on the left side. The mean diameter of mRA was 5.4 ± 1.0 mm in kidneys without aRA and 4.6 ± 10 mm in kidneys with aRA on the right side and on the left side the mean diameter of mRA was 5.59 ± 1.12 mm in kidneys without aRA and 4.7 ± 1.2 mm in kidneys with aRA. Discussion and Conclusion: The presence of additional renal arteries is very probable when the main renal artery has a diameter of < 4.15 mm. Kidneys presenting a main renal artery > 5.5 mm very probably do not present additional renal arteries. Hence, the renal artery diameter is a factor which should be considered for predicting the presence of additional renal arteries.
Keywords: Accessory renal artery, renal artery, renal artery diameter
|How to cite this article:|
Nagar A, Pasricha N, Sthapak E, Gurjar D, Lal H. A computed tomography angiography study to correlate main renal artery diameter with presence of accessory renal artery in healthy live kidney donors. J Anat Soc India 2020;69:196-200
|How to cite this URL:|
Nagar A, Pasricha N, Sthapak E, Gurjar D, Lal H. A computed tomography angiography study to correlate main renal artery diameter with presence of accessory renal artery in healthy live kidney donors. J Anat Soc India [serial online] 2020 [cited 2021 Jan 22];69:196-200. Available from: https://www.jasi.org.in/text.asp?2020/69/4/196/305376
| Introduction|| |
Renal artery variations are common in the general population and the frequency of variations shows social and racial differences., Variations are more common in Africans and Caucasians and seen less common in Indians. The frequency of extrarenal arteries shows variability from 9% to 76% and is generally between 28% and 30% in anatomic and cadaveric studies.,, The renal arteries have been conventionally described as the lateral branches of the abdominal aorta arising inferior to the origin of the superior mesenteric artery.
Variation in the pattern of renal arteries has been reported more frequently than other large vessels in the literature and alternative nomenclatures have been used to describe the same, these include aberrant artery, supernumerary artery, etc., Graves (1956) states that any artery arising from the aorta in addition to the main renal artery should be named accessory and the arteries arising from sources other than the aorta should be called “aberrant.” According to the law of poiseuille, the most important factor determining the volume of blood flow in a vessel is the diameter of the vessel and the flow is directly proportional to the fourth power of vessel diameter It is imperative that artery supplying the kidney should have a sufficient caliber to supply the organ with the amount of blood it needs. The diameter of a renal artery in a kidney supplied by >1 artery can be expected to be smaller than that of the renal artery in a kidney supplied by that single artery. Thus, it can be safely derived that the blood supply to a kidney is dependent on both the number of vessels supplying the kidney and their diameters.
Since renal transplantation is the treatment of choice for patients with end-stage renal failure and kidney transplantation with accessory renal arteries pose a challenge to the surgeon due to higher risks of complications, both vascular and urological it is of utmost importance that the surgeon enters the operative field armed with the most accurate information about the vascular supply of the kidney.
In the past, extensive research has been undertaken on the renal arteries, both cadaveric and using imaging techniques such as ultrasonography, angiography, computed tomography (CT), and magnetic resonance imaging.,,, Digital angiography is considered to be the gold standard for studying the renal arterial anatomy, but CT angiography carries fewer risks and is more accurate with better detailing of the vessel wall and lumen., Thus, whenever surgical procedures such as partial nephrectomies, pyeloplasty for uretropelvic junction stenosis, and kidney transplantation are planned, the correct anatomical information, especially regarding to vascular supply can affect the chosen surgical technique.,, Thus, a prospective study was undertaken to investigate the relationship between the diameter of the main renal artery and the presence of an accessory renal artery by CT-angiography.
Aims and objectives
To find out the relationship between diameter of the main renal artery with the presence of an accessory renal artery.
| Material and Methods|| |
The study was conceptualized in the department of anatomy and was done in collaboration with the department of nephrology and radiology of an institute running a regular kidney transplant program. Prior approval from the Institutional Ethical Committee of the institute was obtained.
The study group consisted of 115 healthy kidney donors (92 women and 23 men with mean age 45.46 years) who presented to the nephrology and radiology department for voluntary kidney donation. All CT examinations were performed on a 64-slice CT scanner in the arterial phase. The number of renal arteries supplying each kidney was evaluated and their diameters were measured.
A total of 80–100 ml of 300 mg/ml intravenous contrast material plus a 20-ml chaser bolus was injected through an 18-gauge cannula positioned in an antecubital vein at a flow rate of 4 ml/s by a dual-head power injector. An automatic triggering system provided the scanning delay time to obtain an arterial phase image. For this purpose, a single unenhanced low-dose scan was first obtained. Based on this image, a region of interest (ROI) with an area of 1 mm2 was then established by CT technologist in the lumen of the aorta at the level of the superior mesenteric artery. The patient was instructed to hold his breath as soon as the signal density in this ROI reached a threshold of 180 Hounsfield units, and the scan was initiated. The scanning delay time was 18–24 s after the start of the injection.
In our study, the main renal artery was taken as the artery with the largest caliber and originating at the expected level in case of >1 artery supplying the kidney.
The measurement of the RA diameter was performed in the proximal segment of the renal artery at a distance of 1–1.5 cm from the ostium, where the renal artery reaches a uniform width. The data of each patient with the number of arteries supplying the kidney and their diameter were tabulated.
The results were expressed as the ± standard deviation. The mean differences among the groups with and without accessory renal artery (aRA) were evaluated using the Student's t-test, and the correlations with mRA diameter were evaluated by Pearson's correlation analysis.
| Results|| |
The data for 115 healthy kidney donors were analyzed, 23 (20%) of whom were male and 92 (82%) were female. The mean age of the female kidney donors was 45.52 years and the mean age of the male kidney donors was 44.26 years (total mean age of male and female was 45.26 years) [Table 1].
Eighty-six (75%) of the 115 kidneys of the right side and 88 (76.52%) of the 115 kidneys of the left side had a single RA (with no aRA) [Figure 1] and [Figure 2], whereas 29 (25%) had one or more aRA on the right side [Figure 3] and [Figure 4] and 27 (23.48%) had one or more aRA on the left side [Figure 5] and [Figure 6]. Fifty-six of the 230 kidneys had aRA. No aberrant renal artery was found.
|Figure 3: The mRA diameter of a kidney without an aRA and with aRA in the right kidney|
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|Figure 5: Comparison of mRA between the subjects having/not having aRA in left side|
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The mean diameter of mRA was 5.4 ± 1.0 mm in kidneys without aRA and 4.6 ± 1.0 mm in kidneys with aRA on the right side and on the left side the mean diameter of mRA was 5.59 ± 1.12 mm in kidneys without aRA and 4.7 ± 1.2 mm in kidneys with aRA [Table 2] and [Table 3].
|Table 2: Comparison of mRA between the Subjects having/not having aRA in Right Side|
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|Table 3: Comparison of mRA between the Subjects having/not having aRA in Left Side|
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The mRA diameter was smaller in kidneys with aRA than in those without aRAs (P < 0.001 on the right side and P < 0.0001 on the left side).
The absence or presence of an aRA was predicted by applying a Binary Regression Analysis [Table 4]. After including the parameter Side and Diameter of mRA in the Binary Logistic Regression Analysis to Predict Absence/Presence of aRA the regression equation of prediction was found to be:
|Table 4: Validity Parameters of the Logistic Regression Predictive Model to Predict Absence/Presence of aRA|
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Pr = 2.717–0.007 × Side – 0.760× mRA
In the above equation Side = 1 if there is right side else Side = 0
mRA represents the diameter of mRA.
The presence of aRA predicted if Pr > 0.5.
The above model has predictive accuracy of 77.4%.
Binary Logistic Regression Analysis to Predict Absence/Presence of aRA by the Side and Diameter of mRA.
A poor sensitivity (only 14.3%) was found for the fitted logistic regression model. However, the model has a good specificity of 97.7% and accuracy (77.4%). To predict the presence of aRA on the basis of side and diameter of mRA then a positive value of Predictive value (Pr) meant aRA present, but in that case, only among 14.3% cases we actually found the presence of aRA. On the other hand, a negative value of Pr meant aRA is absent, and in that case, prediction will be accurate in 97.7% cases that is we actually found the absence of aRA. Hence, the overall accuracy of model is 77.4%.
| Discussion|| |
Embryologically kidney develops from pronephros, mesonephros, and metanephros. The former two regresses but the arterial network to these segments may remain and lead to supernumerary renal arteries. Knowledge of the arterial anatomy of the kidney is important in partial and complete nephrectomies. If there is a single renal artery it is considered as favorable factor with a lower incidence of complications. Bleeding due to an invasive procedure performed on an aRA may result in open laparotomy. Missed case of an aRA may cause infarct in a transplanted kidney and associated hypertension in the recipient. It has been documented that the presence of variations increases the likelihood of warm ischemia time, vascular thrombosis, hemorrhage, difficulty in carrying out anastomosis, and greater risk of urinary fistulas and urethral lesions.,
Accessory renal arteries constitute the most common, clinically important renal vascular variant. The prevalence of an aRA has been generally accepted to be approximately 25%–30% in different study series.,,,, The prevalence of aRA in our study group (24%) was similar to that described in the literature. Cadaveric studies have also found >1 aRA in different studies with the incidence of 2%–3%, but we could not find a 3rd renal artery supplying the kidney in our study.
Not only the number of arteries supplying the kidney but also the orthogonal diameter of each artery is important information for the radiologists and surgeons before any intended instrumentation. According to a study carried out by Aytac et al. using sonography and digital subtraction angiography, it was derived that if the renal arterial diameter is 4.65 mm or less there is quite probability of an accessory renal artery, and if it is <4.15 mm the probability of an accessory increases with 98% specificity. They also concluded that if they encountered mRA diameter 5.5 mm or more, they could not find an accessory renal artery. In our study too we found out that the mRA diameter was smaller in kidneys with aRA than in those without aRAs. In our study, the mean renal artery diameter in case of absent aRA was 5.40 mm (right side) and 5.59 mm (left) which was significantly more as compared to cases with present aRA, 4.6 mm (right), and 4.7 mm (left) (P < 0.001 in the right side and P < 0.0001 in left side).
Our study suggests that the diameter of the main renal artery supplying the kidney is a key factor to be investigated and documented before proceeding with any interventions such as transplant or nephrectomies.
| Conclusion|| |
In light of the fact that there is limited surgical visibility and exposure in laparoscopic nephrectomies and complications associate with accessory renal arteries, it is imperative to have a thorough knowledge about renal vasculature before any intervention is planned. The statistically significant difference in diameter of mRA in kidneys without aRA and in kidneys with aRA shows that the renal artery diameter is a factor which should be considered preoperatively for predicting the presence of additional renal arteries.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]