Anatomical background for nephron-sparing surgery in renal cell carcinoma

Cadaveric study of arterial renal anatomy and its surgical implications in partial nephrectomy

PURPOSE

Partial nephrectomy is gaining, nowadays, more interest in oncologic kidney surgery. This type of surgery requires the good knowledge of vascular renal anatomy to make it safe and to guarantee good functional and oncological outcomes. This paper exposes the clinical implication of the arterial renal anatomy in nephron-sparing surgery.

METHODS

This is a cadaveric study of 71 human kidneys performed at Charles Nicolle mortuary. The right and left kidneys with surrounding tissues were removed en bloc with the adjacent part of the aorta and inferior vena cava, cleared and studied. Colored resin was injected in each artery, vein, and urinary ducts, with a specific color code for each structure. Corrosion technique was used to eliminate the surrounding tissue, leaving only the colored resin matrix. The Ternon anatomic classification of the inferior polar artery, based on its emergence point was used.

RESULTS

Multiple renal arteries were noted in 9.85% of casts. Anterior and posterior division of main renal artery was found in 95.7% of cases. Posterior segmental artery crossed posteriorly the upper caliceal infundibulum and the renal pelvis in 93% of cases. The upper renal pole was vascularized by an apical segmental artery in 16.9% of cases and a superior polar artery in one case (1.4%). The mid pole of the kidney was supplied by a unique anterior branch and a single posterior branch in 40% of cases. Inferior polar artery was found in 52 casts (73.23%). Type I of Ternon was found in 6 casts (11.53%), Type II in 25 cases (48.07%), Type III in 19 cases (36.53%), Type IV in 2 cases (3.84%), and type V in 13 casts (25%).

CONCLUSION

Renal vascular anatomy presents large variations. Good knowledge of the segmental arterial anatomy of the kidney is a primordial to a safe partial nephrectomy. Good preoperative vascular mapping can be of great help for the surgeon.

Anatomical background of ovine kidney for use as animal model: analysis of arterial segmentation, proportional volume of each segment and arterial injury after cranial pole partial nephrectomy

OBJECTIVE

To study the arterial segments of ovine kidney, present a proportional volume analysis of each kidney arterial segment, and analyze arterial injuries caused by simulated partial nephrectomy of cranial pole.

MATERIALS AND METHODS

Forty-eight ovine kidneys injected with polyester resin into the renal arteries and collecting system were used in this study. Eighteen kidneys were used to study the arterial segments and the proportional volume of each renal segment. Other 30 kidneys were submitted to superior pole resection at a distance of 1.0cm, 0.5cm, or exactly at the cranial hilar edge, just before the resin hardening. These endocasts were used to evaluate the arterial injuries caused by these different resection planes.

RESULTS

Ovine renal artery divided into two (ventral and dorsal) or three segmental arteries. Dorsal segment presented higher proportional volume than ventral segment. For kidneys with three segments, the third segment was on the caudal region (caudo-ventral or caudo-dorsal segment) and presented the lowest proportional volume. None of the resected kidneys (at 1.0, 0.5 or at the cranial hilar edge) presented injury of arterial branches that irrigate non-resected region.

CONCLUSION

The segmental distribution of renal artery, the proportional volume of each segment and arterial injuries after cranial pole resection in ovine kidneys are different from what is observed in human kidneys. Meanwhile, ovine kidneys show a primary segmental division on anterior and posterior, as in humans, but different from swine. These anatomical characteristics should be considered when using ovine as animal models for renal experimental and/or training procedures.

Percutaneous Nephrolithotomy Puncture and Tract Dilation: Evidence on the Safety of Approaches to the Infundibulum of the Middle Renal Calyx

OBJECTIVE

To investigate the anatomical relations of the papillary, infundibular, and pelvic approach to percutaneous nephrolithotomy and evaluate the amount of vascularization at the respective sites.

MATERIALS AND METHODS

^99mTc-dimercaptosuccinic acid single-photon emission computed tomography/computed tomography (SPECT/CT) renal scintigraphies or computed tomography perfusion (CTP) was performed in 40 patients (prone n = 20 or supine position n = 20). The angle of approach (AoA) for access tracts and the respective regions of interest to the mid-calyceal papilla and infundibulum as well as renal pelvis were designed and compared.

RESULTS

The design of access tracts aiming to the renal pelvis, papilla, and infundibulum of the renal calyx was impossible for the nondilated collecting systems as all these tracts were in close vicinity. In both SPECT/CT and CTP, there was no statistical difference between the AoA for infundibular or pelvic access in comparison with the papillary puncture in either prone or supine position regardless of the degree of dilation of the system. The comparison of the measurements in the regions of interest showed that there was no difference in blood supply between the infundibular and pelvic access in comparison with the papillary approach in both positions regardless of the degree of collecting system dilation.

CONCLUSION

The use of SPECT/CT and CTP showed that the punctures to the mid-calyceal renal papilla-fornix and infundibulum as well as the renal pelvis at the same level have similar AoA. The sites of the parenchyma involved in the tract dilation of the respective approaches are not related to significant differences in terms of vascularization.

Off-Clamp Renal Tumourectomy by Retroperitoneoscopy in Posterior Renal Tumours of Medium Complexity (Padua score 8-9)

BACKGROUND

The guidelines recommend partial surgery for T1 renal tumours. Various aspects of this surgery have evolved in recent years, including the clamping method and duration, enucleation, the retroperitoneoscopic approach and the use of 3mm ports. We present our initial series on laparoscopic renal tumourectomy by retroperitoneoscopy (LRTR) and analyse our learning curve and use of 3-mm instrumentation.

MATERIAL AND METHODS

From January 2011 to January 2015, we performed LRTR on 50 patients with posterior or convex T1 renal tumours. After 10 cases, the technique changed to off-clamp, and 11 cases were subsequently performed with 3mm instrumentation.

RESULTS

The mean tumour size was 34.36 mm (14-62), with a mean PADUA score of 8.42 (5-12). The mean operative time was 163.1 minutes (75-300), and the mean warm ischaemia time was 4.21 minutes (0-28). The main renal artery was not clamped in 41 (82%) patients, and no vessel (zero ischaemia) was clamped in 39 (78%) patients. Seven cases had positive margins (6 focal). Eleven LRTRs were performed with 3mm instrumentation, with shorter surgical times, less intraoperative bleeding and shorter hospital stays.

CONCLUSIONS

Retroperitoneoscopy coupled with enucleation enables the extirpation without clamping of posterior renal tumours, with a relatively short learning curve. The 3-mm material enables the technique to be performed, although in our experience it has resulted in a higher rate of positive surgical margins.

Anatomical relationship between the collecting system and the intrarenal arteries in the rabbit: contribution for an experimental model

Intrarenal anatomy was studied in detail to evaluate how useful rabbits could be as a urologic model. Only one renal artery was observed, which was divided into dorsal and ventral branches in all cases. Three segmental arteries (cranial, mesorenal and caudal) was the most frequent branching pattern found in both the dorsal and ventral division. There was an important artery related to the ureteropelvic junction in both dorsal and ventral surfaces in all specimens. The cranial pole was supplied by both dorsal and ventral divisions of the renal artery in 23 of 41 casts (56%). Although the cranial pole of the rabbit kidney could be useful as a model because of the resemblances with human kidney, the different relationship between the intrarenal arteries and the kidney collecting system in other regions of the kidney must be taken into consideration by the urologists, when using rabbit kidney in urological research.

Contribution of large pig for renal ischemia-reperfusion and transplantation studies: the preclinical model

Animal experimentation is necessary to characterize human diseases and design adequate therapeutic interventions. In renal transplantation research, the limited number of in vitro models involves a crucial role for in vivo models and particularly for the porcine model. Pig and human kidneys are anatomically similar (characterized by multilobular structure in contrast to rodent and dog kidneys unilobular). The human proximity of porcine physiology and immune systems provides a basic knowledge of graft recovery and inflammatory physiopathology through in vivo studies. In addition, pig large body size allows surgical procedures similar to humans, repeated collections of peripheral blood or renal biopsies making pigs ideal for medical training and for the assessment of preclinical technologies. However, its size is also its main drawback implying expensive housing. Nevertheless, pig models are relevant alternatives to primate models, offering promising perspectives with developments of transgenic modulation and marginal donor models facilitating data extrapolation to human conditions.

Localized renal cell carcinoma management: an update

OBJECTIVE

To review the current modalities of treatment for localized renal cell carcinoma.

MATERIALS AND METHODS

A literature search for keywords: renal cell carcinoma, radical nephrectomy, nephron sparing surgery, minimally invasive surgery, and cryoablation was performed for the years 2000 through 2008. The most relevant publications were examined.

RESULTS

New epidemiologic data and current treatment of renal cancer were covered. Concerning the treatment of clinically localized disease, the literature supports the standardization of partial nephrectomy and laparoscopic approaches as therapeutic options with better functional results and oncologic success comparable to standard radical resection. Promising initial results are now available for minimally invasive therapies, such as cryotherapy and radiofrequency ablation. Active surveillance has been reported with acceptable results, including for those who are poor surgical candidates.

CONCLUSIONS

This review covers current advances in radical and conservative treatments of localized kidney cancer. The current status of nephron-sparing surgery, ablative therapies, and active surveillance based on natural history has resulted in great progress in the management of localized renal cell carcinoma.

Physiological modeling of tumor-affected renal circulation

One way of gaining insight into what can be observed in medical images is through physiological modeling. For instance, anatomical and functional modifications occur in the organ during the appearance and the growth of a tumor. Some of these changes concern the vascularization. We propose a computational model of tumor-affected renal circulation that represents the local heterogeneity of different parts of the kidney (cortex, medulla). We present a simulation of vascular modifications related to vessel structure, geometry, density, and blood flow in case of renal cell carcinoma. We also use our model to simulate computed tomography scans of a kidney affected by the renal cell carcinoma, at two acquisition times after injection of a contrast product. This framework, based on a physiological model of the organ and physical model of medical image acquisition, offers an opportunity to help radiologists in their diagnostic tasks. This includes the possibility of linking image descriptors with physiological perturbations and markers of pathological processes.

Pig kidney: anatomical relationships between the renal venous arrangement and the kidney collecting system

PURPOSE

We present a systematic study of the anatomical relationship between the intrarenal veins and the kidney collecting system in pigs.

MATERIALS AND METHODS

The intrarenal anatomy (collecting system and veins) was studied in 61, 3-dimensional endocasts of the kidney collecting system together with the intrarenal veins.

RESULTS

There are free anastomoses between the intrarenal veins. The interlobar veins unite to produce large venous trunks, which form the renal vein. In our study we observed 2 trunks (cranial and caudal) in 54 of the 61 cases (88.53%) and 3 trunks (cranial, middle and caudal) in 7 (11.47%). Only the ventral surfaces of the cranial and caudal poles were drained by large veins, while the dorsal surfaces emptied by anastomoses into the ventral interlobar veins. There were large veins in a close relationship to the ventral surface (90.16%) and to the dorsal surface (3.28%) of the ureteropelvic junction. In 33 of the 61 cases (54.10%) there was 1 or 2 small dorsal veins.

CONCLUSIONS

Although some results of intrarenal venous arrangement in pigs could not be completely transposed to humans, many similarities of pig and human kidneys support its use as the best animal model for urological procedures.

Dog kidney: anatomical relationships between intrarenal arteries and kidney collecting system

The detailed findings of canine intrarenal anatomy (collecting system and arteries) are presented. Ninety-five three-dimensional endocasts of the kidney collecting system together with the intrarenal arteries were prepared using standard injection-corrosion techniques and were studied. A single renal artery was observed in 88.4% of the casts. The renal artery divided into a dorsal and a ventral branch. Using the branching pattern of the ventral and dorsal divisions of the renal artery, the vessels were classified in type I or type II. Type I presented a cranial and a caudal artery, whereas type II presented a mesorenal and a caudal artery. Cranial branches of dorsal and ventral arteries supplied the cranial pole in 90.5% of the specimens. Caudal branches of the dorsal and the ventral divisions of the renal artery irrigated both the caudal pole and the mid-zone of the kidney in 95.8% and 98.9% of the cases, respectively. In all casts, caudal branches of both dorsal and ventral arteries supplied the caudal pole. Therefore, the caudal branches of the ventral and dorsal divisions of the renal artery are of utmost importance in the kidney arterial supply. Although many results of renal and intrarenal anatomy in dogs may not be completely transposed to humans, the anatomical relationship between arteries and the collecting system in the cranial pole of the dog kidney is similar to those in man. This fact supports the use of the dog as an animal model for urologic procedures at the cranial pole.

Proportional Analysis of Pig Kidney Arterial Segments: Differences from the Human Kidney

PURPOSE

To present a systematic study and a proportional analysis of the arterial segments of the pig kidney.

MATERIALS AND METHODS

Sixty-one three-dimensional endocasts of the arterial segments of pig kidneys were studied. Each segment was injected with a resin of a different color. Cavalieri's principle was used to calculate the volume of each renal segment, and these results were compared with the results from the point-counting planimetry method used on photographs of pig-kidney surfaces.

RESULTS

Two to five renal segments were observed. Division into two segments, a cranial and a caudal, was the most common (42.62%). The renal volume ranged from 101 to 173 cm(3) (mean 130.85 cm(3)). The cranial segment was present in 39 of the 57 casts (68.42%). It presented the greatest median value of proportional area (50.00%) and also the greatest maximum value of proportional area, accounting for as much as 74.04% of the total kidney area. The ventral segment, which was found in 20 of the 57 casts (35.09%), presented the lowest median value of proportional area (13.87%) and showed the most variation in area (coefficient of variation 72.89%). There was no significant statistical difference between the segmental areas as evaluated by Cavalieri's principle and by the point-counting planimetry method.

CONCLUSIONS

The distribution and size of the renal-arterial segments in pigs are not similar to those of the human kidneys. Therefore, this information must be taken into account by practitioners of urologic training or ablation using pigs as the animal model, as the structure of the porcine arterial segments cannot be transposed to humans.

[Conservative treatment of upper urinary tract tumours]

The conservative management of kidney cancer is widely accepted as a therapeutic option for tumours measuring less than 4 cm or in case of underlying renal disease and solitary kidney. The functional and carcinologic success of this conservative treatment results from a radical resection of the tumour and a careful repair of the collecting system and selective ligature of the vessels. Kidney artery clamping is a key to reach these objectives. The cooling of the kidney preserves from warm ischemia and reperfusion lesions. In this review, we explain the physiological basis of warm ischemia induced kidney lesions due to the kidney artery clamping and the advantage of hypothermia. The surgical technique as described by Novick is detailed. This well standardized technique has the advantage of being reproducible and adaptable to all situations.

PIG KIDNEY: ANATOMICAL RELATIONSHIPS BETWEEN THE INTRARENAL ARTERIES AND THE KIDNEY COLLECTING SYSTEM. APPLIED STUDY FOR UROLOGICAL RESEARCH AND SURGICAL TRAINING

PURPOSE

We present a systematic study of the anatomical relationships between intrarenal arteries and the kidney collecting system in pigs.

MATERIALS AND METHODS

The intrarenal anatomy (collecting system and arteries) was studied in 91, 3-dimensional endocasts of the kidney collecting system together with the intrarenal arteries.

RESULTS

Some anatomical details that have importance to help research and surgical training in urology when using the pig as an animal model were observed and described. It was found that there was only 1 artery per kidney. This artery divided into cranial and caudal branches in 85 cases (93.4%). In 6 cases (6.6%) the primary division of the renal artery was in a dorsal and in a ventral branch. In all cases 2 arteries (1 ventral and 1 dorsal) involved the cranial caliceal group. In the dorsal mid zone a dorsal artery originated from the cranial division of the renal artery, which was obliquely positioned in 47.25% of cases. The arterial supply related to the ventral mid zone of the kidney consisted of branches that coursed horizontally in the ventral surface of the renal pelvis in 81.32% of cases. The caudal division of the renal artery supplied the ventral and dorsal surfaces of the caudal caliceal group in 84.62% of cases, while in 15.38% a dorsal artery supplied its dorsal surface.

CONCLUSIONS

Although the results of renal and intrarenal anatomy in pigs could not be completely transposed to humans, many similarities in the pig and human intrarenal arteries support its use as the best animal model for urological procedures.

Laparoscopic partial nephrectomy for a renal tumor with tumor-feeding artery ligation: Left renal cell carcinoma in the posterior mid zone

The most serious problem regarding a laparoscopic partial nephrectomy is how to perform bloodless excision without causing renal ischemia in a limited working space. We report the case of a 65-year-old man with left small renal cell carcinoma in the posterior mid zone who underwent a laparoscopic partial nephrectomy through a retroperitoneal approach by carrying out the ligation of the tumor-feeding artery, but without clamping the renal pedicle. Both preoperative abdominal computed tomography (CT) and intraoperative ultrasonography revealed the tumor to be fully encapsulated. The tumor-feeding artery could be exposed by dissection from the renal hilum and, after an arterial ligation, tumor resection with a safety margin was smoothly performed with minimal bleeding. Postoperatively, CT revealed a limited defect of the renal parenchyma and excretory pyelography showed no urine leakage or urinary tract obstruction. The preoperative and postoperative creatinine levels were 0.66 and 0.69 mg/dL, respectively. As a result, a tumor-feeding artery ligation with a laparoscopic partial nephrectomy for left renal cell carcinoma in the posterior mid zone is considered to be an effective surgical modality which avoids renal ischemia and pelvic heat injury.

[Role of partial nephrectomy in the treatment of kidney cancer]

Incidental finding of small renal carcinoma by radiologic exams (ultrasound, computed tomography, MRI) performed for non urological purposes raises therapeutic and management problems (therapeutic abstinence and surveillance, partial or radical nephrectomy). Radical nephrectomy is recognized as a curative treatment for renal cell carcinoma. However, partial nephrectomy was suggested for renal cell carcinoma of solitary functional kidney or bilateral tumors in order to avoid dialysis or renal transplantation. The debate remains open for the small renal carcinomas with a normal controlateral kidney. Is partial nephrectomy an adequate treatment or rather perform radical nephrectomy? The present study was performed to analyse the published literature on the subject.

Renal anatomy. Endourologic considerations

The general anatomy of the kidney as applied to minimally invasive surgery is described. The kidney morphometry, the spatial planes, and the perirenal coverings are presented. The kidney's relationship with the diaphragm, ribs, pleura, liver, spleen, and colon is described in importance of intrarenal access. The intrarenal anatomy is also described, based on a large series of three-dimensional endocasts. The anatomic relationships of the intrarenal vessels (arteries and veins) with the kidney collecting system are presented and discussed with respect to intrarenal access by puncture, for endopyelotomy and for nephron-sparing operations.

Proportional analysis of the kidney arterial segments

The proportional area of each renal arterial segment was analyzed in 49 polyester resin corrosion endocasts of the renal vasculature. We defined a segmental artery as a primary or secondary branch of the renal artery that could be isolated outside the hilum. We found kidneys with five arterial segments in 30 of 49 casts (61.2% of cases) and kidneys with four arterial segments in 19 of 49 casts (38.8%). To enable the evaluation of the proportional areas of the autonomous segments (by using the "point-counting planimetry method"), each arterial segmental branch was injected with different-colored resin. The superior segment (apical) was present in 36 of 49 casts (73.5% of cases) and had a median proportional area of 13.02%. The anterosuperior and anteroinferior segments were present in 30 of 40 casts (61.2% of cases) and had median proportional areas of 21.36% and 17.18%, respectively. The anterior segment was present in 19 of 49 casts (38.8% of cases; when the mid-kidney anterior surface received only one segmental artery) and had a median proportional area of 28.44%. The inferior segment was present in 100% of cases and had a median proportional area of 22.65%. The posterior segment was also present in 100% of cases and was the segment with the greatest median proportional area (33.76%).