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Functional and Morphological Effects of Postpercutaneous Nephrolithotomy Superselective Renal Angiographic Embolization
Endourology/MIS Functional and Morphological Effects of Postpercutaneous Nephrolithotomy Superselective Renal Angiographic Embolization Ahmed R. EL-Nahas, Ahmed A. Shokeir, Tarek Mohsen, Hossam Gad, Ahmed M. El-Assmy, Tarek El-Diasty, and Hamdy A. El-Kappany OBJECTIVES METHODS
RESULTS
CONCLUSIONS
To evaluate the functional and morphological effects of postpercutaneous nephrolithotomy (PCNL) superselective renal angiographic embolization. Between January 1995 and March 2006, superselective renal angiography was needed to control severe bleeding after 41 of 4095 PCNL procedures (1%). We evaluated the short-term effects of embolization after 3 months with renal ultrasonography (RUS), dimercaptosuccinic acid (DMSA) renal scan, and estimation of serum creatinine. We evaluated long-term morphological and functional effects with RUS, DMSA renal scan, and excretory urography (IVU). Bleeding was controllable with superselective embolization in 38 patients (93%). Six of them developed early postembolization complications, in the form of perinephric hematoma in 4 and urinary leakage in 2 patients. At 3 months, serum creatinine levels increased in 3 of 9 patients with a solitary kidney, but none required renal replacement therapy. Long-term follow-up was completed for 30 patients for a mean period of 3.9 ⫾ 2.3 years. We performed IVU for 27 patients. Among them, 2 renal units (7%) showed no dye excretion. DMSA scans showed homogeneous distribution of radiotracer with no evidence of photopenic areas in 6 renal units (20%). The mean percentage of DMSA uptake by the corresponding kidney improved from 25 ⫾ 9% at the 3-month scans to 34 ⫾ 11% at the last follow-up scans (P ⬍0.001). The short-term deleterious effects of superselective renal embolization for post-PCNL renal vascular injuries were more pronounced in patients with a solitary kidney. However, the long-term follow-up showed functional and morphological improvements. UROLOGY 71: 408 – 412, 2008. © 2008 Elsevier Inc.
P
ercutaneous nephrolithotomy (PCNL) is the treatment of choice for large and complex renal calculi.1 Yet, it is an invasive procedure and complications are not totally avoidable. Renal hemorrhage is the most dangerous complication of PCNL. Fortunately, conservative measures are adequate to control bleeding in most cases and angiographic embolization is required in less than 1% of cases.2– 4 Transcatheter superselective renal embolization of the injured vessel has proved to be a life-saving treatment in more than 90% of cases.3– 6 The main concerns of embolization are the adverse effects that may result from devascularization of a portion of the renal parenchyma with subsequent loss of its function. Overall, the literature on the effects of superselec-
tive embolization on renal function and morphology are scant and most series have a small number of kidneys or heterogeneous groups of patients.7,8 We conducted this study to evaluate the functional and morphological effects of post-PCNL superselective renal angiographic embolization. We tried to overcome the limitations of the previous research by providing a single institutional study containing a large number of patients with long-term follow-up. To the best of our knowledge, the present study contains the largest number of patients with the longest duration of follow-up in the urological literature.
PATIENTS AND METHODS Patients
From the Departments of Urology and Radiology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt Reprint requests: Ahmed A. Shokeir, M.D., Ph.D., F.E.B.U., Professor of Urology, Mansoura Urology and Nephrology Center, Mansoura, Egypt. E-mail: [email protected] Submitted: June 30, 2007, accepted (with revisions): October 19, 2007
408
© 2008 Elsevier Inc. All Rights Reserved
We retrospectively reviewed the computerized data of 3262 patients who underwent 4095 PCNL procedures from January 1995 through March 2006 at our center. Renal bleeding that was not controlled with conservative measures such as clamping of the nephrostomy tube, adequate hydration, diuretics, and 0090-4295/08/$34.00 doi:10.1016/j.urology.2007.10.033
Table 1. Patients and renal characteristics of 41 cases requiring superselective angiography Character Sex Male Female Side Right Left Renal morphology No abnormalities Hydronephrosis Pyelonephritis Renal unit Not solitary Solitary Stone burden Single Multiple Staghorn Recurrence No Yes No. of tracts Single Multiple Figure 1. Left superselective renal angiography showing a small pseudoaneurysm arising from a peripheral branch of the middle segmental artery.
hemostatic drugs, or severe bleeding leading to hemodynamic instability, was treated with transcatheter superselective renal angiography.
Technique of Embolization Experienced interventional radiologists performed all embolization procedures. The procedure started with selective renal angiography to identify the site and nature of the vascular injury. Platinum microcoils 0.035 inch (Boston Scientific, Boston, Mass) were delivered through the 6-Fr angiographic catheter (Copra II; Terumo, Osaka, Japan) for segmental arterial lesions. We used 0.018-inch helical platinum microcoils through the 3-Fr coaxial microcatheter (Target Therapeutics, Fremont, Calif) for lesions in subsegmental peripheral arteries (Fig. 1). At the end of the embolization procedure, we performed angiography to confirm complete occlusion of the injured vessel.
No. (%) 26 (63) 15 (37) 17 (41.5) 24 (58.5) 10 (24) 20 (49) 11 (27) 32 (78) 9 (22) 13 (32) 19 (46) 9 (22) 27 (66) 14 (34) 29 (71) 12 (29)
carried out in patients with serum creatinine less than 1.8 mg/dL.
Technique of DMSA Scans We obtained images 2 hours after intravenous injection of 99m Tc-DMSA (Medi-Physics, Arlington Heights, Ill) at a dose of 1.6 to 2 MBq/kg. We used a state-of-the-art triple-detector gamma camera (SMV DST.Xli; GE, Milwaukee, Wis) equipped with high-resolution collimator and applied a planar scintegraphic technique. The percent (split) radiotracer uptake by the corresponding renal unit was calculated from the computerized data. A single radiologist reviewed all images for determination of the distribution of the radioactive tracer (homogeneous or heterogeneous) and the presence of a single or multiple photopenic (cold) areas.
Statistical Analysis We compared changes in the percentage of renal uptake of the radiotracer by the corresponding kidney measured at short-term and long-term follow-up using t-test (two- tailed).
Follow-up
RESULTS
We recorded all postembolization complications. We evaluated the short-term effects of embolization after 3 months with renal ultrasonography (RUS), dimercaptosuccinic acid (DMSA) renal scan, and estimation of serum creatinine. Then, we performed regular follow-up with RUS and serum creatinine every 3 months for 1 year. After the local ethical committee approved the study protocol, patients were recruited for long-term evaluation of the morphological and functional effects of embolization on the kidney. They were clinically evaluated for new onset of hypertension, and serum creatinine was estimated. Radiological investigations included RUS and DMSA renal scan for all patients. Moreover, excretory urography (IVU) was
Of the 4095 PCNL procedures, 41 (1%) required transcatheter superselective renal angiography. Table 1 lists patients’ demographic profile and renal and stone characteristics that required embolization. The mean age was 51 ⫾ 12 years (range, 25 to 80 years). Renal angiography revealed pseudoaneurysm in 22 patients, arteriovenous fistula (AVF) in 8, and both lesions in 7 patients, whereas arterial laceration was seen in 4 patients. Vascular injuries were related to the upper, middle, and lower segmental renal vessels in 11, 6, and 22 patients, respectively, whereas injury of both the upper and lower branches was
UROLOGY 71 (3), 2008
409
encountered in 1 patient, and the remaining patient had injury of a large hilar artery. Bleeding could be controlled with superselective embolization in 38 patients (93%). We observed early postembolization complications in 6 patients. We detected perinephric hematomas in 4 patients; conservative management was successful in 3, whereas 1 patient developed perinephric abscess resulting from infection of the hematoma and was treated with percutaneous tube drain. The remaining 2 patients developed urinary leakage through the nephrostomy tract and were successfully managed with double pigtail ureteric stent for 4 weeks. Transcatheter embolization failed to control bleeding in 3 patients: 2 with large AVF and 1 with hilar vascular injury. We performed urgent exploration in all 3 patients. Deep sutures at the site of the nephrostomy tube could control bleeding in the first patient and nephrectomy was required in the second patient. The third patient died during exploration because of profuse internal hemorrhage owing to injury of a large hilar artery. Of the 38 patients, 29 had normal contralateral kidney and 9 had a solitary kidney. At 3-month follow-up, serum creatinine levels were stable in 6 patients with a solitary renal unit, whereas they were elevated in the other 3 patients from preoperative values of 0.8, 1, and 1.3 to 2.5, 3.6, and 6 mg/dL, respectively. During the follow-up period of 3, 2, and 1.5 years, none of these 3 patients required renal replacement therapy. Three months after embolization, RUS revealed complete resolution of all perinephric collections; pyelonephretic changes were present in 10 kidneys and residual nontargeted stones were detected in 6. Long-term follow-up was completed for 30 of 38 patients because 8 patients were lost to follow-up after 3 months, and hence were not included in the evaluation of long-term results. The mean follow-up period was 3.9 ⫾ 2.3 years (range, 1.4 to 9.2 years). Of the 30 patients, 18 had hypertension before PCNL and 1 of the remaining 12 developed hypertension 3 years after PCNL. However, this patient had multiple risk factors for development of essential hypertension, including obesity and hypercholesterolemia. We performed IVU in 27 patients because 3 had high serum creatinine. It showed good contrast excretion without abnormalities in the caliceal configuration in 19 renal units (70%), whereas pyelonephretic changes were observed in 6 (22%) and the remaining 2 renal units (7%) showed no contrast excretion. We detected recurrence of renal stones in 9 patients (30%); 7 of them were treated with extracorporeal shock wave lithotripsy and 2 with PCNL. Table 2 shows results of DMSA scans at 3 months and at last follow-up visit for the 30 patients who completed long-term follow-up. The most important observation was the homogeneous distribution of 99mTc-DMSA with no evidence of photopenic areas in 6 renal units (20%): 4 of them at 3-month follow-up and another 2 at the last 410
Table 2. Results of DMSA scans of corresponding kidney for 30 patients who completed long-term follow-up At 3 Months
At Last Follow-up
DMSA
No. (%)
No. (%)
Single photopenic area Multiple photopenic areas Absent photopenic areas
19 (64) 7 (23) 4 (13)
17 (57) 7 (23) 6 (20)
DMSA ⫽ dimercaptosuccinic acid. Data represent number of renal units.
follow-up scan. The mean percentage of DMSA uptake by the corresponding kidney improved from 25 ⫾ 9% at the 3-month scans to a mean value of 34 ⫾ 11% at the last follow-up scans. This improvement was statistically significant (P ⬍0.001).
COMMENTS Renal vascular injuries during PCNL are frequent, necessitating blood transfusion in 3% to 23%.2–5,9,10 Transcatheter embolization is required in 1% of patients only when simple maneuvers are insufficient to control bleeding. Percutaneous transcatheter embolization is a valuable treatment for most renal vascular injuries.11 It is a minimally invasive intervention that can control bleeding in most patients, thus saving the patient from the morbidity and even mortality that results from severe renal bleeding.12 Moreover, successful superselective embolization of the injured vessel preserves the function of the rest of the kidney parenchyma. Therefore, it is considered first-choice treatment for renal vascular injuries.5– 8 However, the embolization procedure results in an ischemic area of the parenchyma (infarction) with subsequent detrimental effects on renal function. The extent of this infarction and its effect on renal function and morphology have been reported in a few studies.7,8,13 These studies had many limitations and bias such as small number or heterogeneous groups of patients, lack of longterm follow-up, and the use of different methods to evaluate renal function. The present study includes a large homogeneous group of patients (post-PCNL vascular injury) for whom we performed the long-term evaluation of morphological and functional changes by comparing the early and late results of a single imaging study (DMSA). Estimation of serum creatinine level is a rough indicator of renal function, but it may be helpful in patients with a solitary kidney. Perini et al. estimated the likelihood of long-term detrimental effects of embolization for biopsy-related vascular injuries in transplanted kidneys by variations in serum creatinine levels before and after the procedure. They found no detrimental effect in 58% of patients.13 In our study, we observed that 33% of patients with a solitary kidney experienced postembolization deleterious effects in the form of elevation of serum creatinine levels. UROLOGY 71 (3), 2008
After intravenous injection, 99mTc-DMSA is taken up by the proximal tubular cells. Thus, high-spatial-resolution images of the renal cortex can be obtained. The cortical uptake of this radiotracer depends on renal blood flow and proximal tubular cell membrane function. Therefore, the low uptake of DMSA by an area of the renal parenchyma will be confined to a photopenic area that represents the parenchyma supplied by the embolized artery. These special characteristics of 99mTc-DMSA allow qualitative evaluation of the renal cortex morphology and quantitative assessment of split renal uptake of the radiotracer.14,15 In the present study, we performed a comparison to evaluate the early and late results of DMSA scans after superselective embolization. An important observation was the significant improvement of split renal uptake in long-term follow-up. These findings may be due to development of intrarenal collateral supply, which retransfuses the initially ischemic area and prevent total infarction from occurring. Although the renal arteries have been considered end arteries, intrarenal anastmosis exists via the perivascular plexus of segmental, interlobar, and arcuate arteries. The second reason may be the use of the superselective technique, which is associated with a smaller area of infarction.8,16 Then the infarct acts as a scar, which has the tendency to shrink with time. Poulakis et al. also observed shrinkage of the infarct area and compared the size of the nonperfused area on postembolization angiography with its size on contrast-enhancement computed tomography (CT) scans after a mean follow-up of 40 months.7 The mean size of the infarct area had decreased from 9% in early postembolization angiographic films to 5% in the long-term CT scans. Chaziioannou et al. also found a decrease in the early postembolization infarct area from a mean value of 12% to 6% after a mean follow-up of 12 months using contrast-enhancement CT.8 Another important finding in our study is the absence of photopenic areas in DMSA scans in 20% of patients. Beaujeux et al. had a similar observation and found no renal parenchymal infarction in 3 of 6 patients after superselective embolization of peripheral renal vascular lesions.17 Complete disappearance of the evidence of parenchymal infarction on short-term follow-up may result from revascularization of the embolized artery or retransfusion of this area from adjacent vessels. Such a finding in long-term follow-up may be attributed to shrinkage of a small peripheral infarct. The possibility of missing a small infarct area by using the planar technique of DMSA scan, which gives only two-dimensional images, also cannot be excluded. However, the exact cause needs to be further evaluated using three-dimensional imaging such as 99mTc-DMSA single photon emission CT (SPECT), contrast-enhancement spiral CT, and dynamic magnetic resonance imaging, or studying the hypothesis of revascularization and retransfusion in animal models. In our study we used the planar DMSA scanning UROLOGY 71 (3), 2008
technique for long-term follow-up because it has been used for early evaluation. Before the advent of the coaxial catheter, it was impossible to catheterize subsegmental branches, and embolization had to be performed more proximally, which resulted in a large area of infarction and loss of function.18 In this study and that of Poulakis et al. and Chaziioannou et al., the use of coaxial catheter and microcoils enabled superselective embolization of peripheral arterial branches sufficient to control bleeding and preserve the largest possible renal parenchyma, which was reflected on preservation of renal function.7,8 The theoretical fear of development of hypertension after renal embolization owing to release of rennin from the ischemic parenchyma was not realized, partially because of the lack of long-term follow-up of such patients or because that this did not occur. Our results and those of Beaujeux et al. showed no risk of neo-onset of hypertension after superselective embolization.17 The reasons may be the same as described before for improved function or total replacement of the infarct area by fibrous tissue not capable of rennin release.
CONCLUSIONS Superselective renal embolization is an effective treatment for post-PCNL renal vascular injuries. Short-term deleterious effects were more pronounced in patients with a solitary kidney. However, long-term follow-up showed functional and morphological improvements. References 1. Preminger GM, Assimos DG, Lingeman JE, et al: AUA Nephrolithiasis Guideline Panel Chapter 1: AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations. J Urol 173: 1991–2000, 2005. 2. El-Kenawy MR, El-Kappany HA, El-Diasty TA, et al: Percutaneous nephrolithotomy for renal stones in over 1000 patients. BJU Int 69: 470 – 475, 1992. 3. Martin X, Murat FJ, Feitosa LC, et al: Severe bleeding after nephrolithotomy: results of heperselective embolization. Eur Urol 37: 136 –139, 2000. 4. Srivastava A, Singh KJ, Suri A, et al: Vascular complications after percutaneous nephrolithotomy: are there any predictive factors? Urology 66: 38 – 40, 2005. 5. El-Nahas AR, Shokeir AA, El-Assmy AM, et al: Post-percutaneous nephrolithotomy extensive hemorrhage: a study of risk factors. J Urol 177: 576 –579, 2007. 6. Vignali C, Lonzi S, Bargellini I, et al: Vascular injuries after percutaneous renal procedures: treatment by transcatheter embolization. Eur Radiol 14: 723–729, 2004. 7. Poulakis V, Ferakis N, Becht E, et al: Treatment of renal vascular injury by transcatheter embolization: immediate and long-term effects on renal function. J Endourol 20: 405– 409, 2006. 8. Chatziioannou A, Brountzos E, Primetis E, et al: Effects of superselective embolization for renal vascular injuries on renal parenchyma and function. Eur J Vasc Endovasc Surg 28: 201–206, 2004. 9. Sacha K, Szewczyk W, and Bar K: Massive haemorrhage presenting as a complication after percutaneous nephrolithotomy (PCNL). Int Urol Nephrol 28: 315–318, 1996. 10. Galek L, Darewicz B, Werel T, et al: Hemorrhagic complications of percutaneous lithotripsy: original methods of treatment. Int Urol Nephrol 32: 231–233, 2000.
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11. Schwartz MJ, Smith EB, Trost DW, et al: Renal artery embolization: clinical indications and experience over 100 cases. BJU Int 99: 881– 886, 2007. 12. Pappas P, Leonardou P, Papadoukakis S, et al: Urgent superselective segmental renal artery embolization in the treatment of lifethreatening renal hemorrhage. Urol Int 77: 34 – 41, 2006. 13. Perini S, Gordon RL, LaBerge JM, et al: Transcatheter embolization of biopsy-related vascular injury in the transplant kidney: immediate and long-term outcome. J Vasc Interv Radiol 9: 1011– 1019, 1998. 14. Stokland E, Hellstrom M, Jakobsson B, et al: Imaging of renal scarring. Acta Paediatric Suppl 88: 13–21, 1999.
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15. Piepsz A, Blaufox MD, Gordon I, et al: Consensus on renal cortical scintigraphy in children with urinary tract infection: scientific committee of radionuclides in nephrourology. Semin Nucl Med 29: 160 –174, 1999. 16. Droffner R, Thurnher S, Prokesch R, et al: Embolization of iatrogenic vascular injuries of renal transplants: immediate and follow-up results. Cardiovasc Intervent Radiol 21: 129 –134, 1998. 17. Beaujeux R, Saussine C, Al-Fakir A, et al: Superselective embolization of renal vascular lesions. J Urol 153: 14 –17, 1995. 18. Corr P, and Hacking G: Embolization in traumatic intrarenal vascular injuries. Clin Radiol 43: 262–264, 1991.
UROLOGY 71 (3), 2008
RESULTS
CONCLUSIONS
To evaluate the functional and morphological effects of postpercutaneous nephrolithotomy (PCNL) superselective renal angiographic embolization. Between January 1995 and March 2006, superselective renal angiography was needed to control severe bleeding after 41 of 4095 PCNL procedures (1%). We evaluated the short-term effects of embolization after 3 months with renal ultrasonography (RUS), dimercaptosuccinic acid (DMSA) renal scan, and estimation of serum creatinine. We evaluated long-term morphological and functional effects with RUS, DMSA renal scan, and excretory urography (IVU). Bleeding was controllable with superselective embolization in 38 patients (93%). Six of them developed early postembolization complications, in the form of perinephric hematoma in 4 and urinary leakage in 2 patients. At 3 months, serum creatinine levels increased in 3 of 9 patients with a solitary kidney, but none required renal replacement therapy. Long-term follow-up was completed for 30 patients for a mean period of 3.9 ⫾ 2.3 years. We performed IVU for 27 patients. Among them, 2 renal units (7%) showed no dye excretion. DMSA scans showed homogeneous distribution of radiotracer with no evidence of photopenic areas in 6 renal units (20%). The mean percentage of DMSA uptake by the corresponding kidney improved from 25 ⫾ 9% at the 3-month scans to 34 ⫾ 11% at the last follow-up scans (P ⬍0.001). The short-term deleterious effects of superselective renal embolization for post-PCNL renal vascular injuries were more pronounced in patients with a solitary kidney. However, the long-term follow-up showed functional and morphological improvements. UROLOGY 71: 408 – 412, 2008. © 2008 Elsevier Inc.
P
ercutaneous nephrolithotomy (PCNL) is the treatment of choice for large and complex renal calculi.1 Yet, it is an invasive procedure and complications are not totally avoidable. Renal hemorrhage is the most dangerous complication of PCNL. Fortunately, conservative measures are adequate to control bleeding in most cases and angiographic embolization is required in less than 1% of cases.2– 4 Transcatheter superselective renal embolization of the injured vessel has proved to be a life-saving treatment in more than 90% of cases.3– 6 The main concerns of embolization are the adverse effects that may result from devascularization of a portion of the renal parenchyma with subsequent loss of its function. Overall, the literature on the effects of superselec-
tive embolization on renal function and morphology are scant and most series have a small number of kidneys or heterogeneous groups of patients.7,8 We conducted this study to evaluate the functional and morphological effects of post-PCNL superselective renal angiographic embolization. We tried to overcome the limitations of the previous research by providing a single institutional study containing a large number of patients with long-term follow-up. To the best of our knowledge, the present study contains the largest number of patients with the longest duration of follow-up in the urological literature.
PATIENTS AND METHODS Patients
From the Departments of Urology and Radiology, Urology and Nephrology Center, Mansoura University, Mansoura, Egypt Reprint requests: Ahmed A. Shokeir, M.D., Ph.D., F.E.B.U., Professor of Urology, Mansoura Urology and Nephrology Center, Mansoura, Egypt. E-mail: [email protected] Submitted: June 30, 2007, accepted (with revisions): October 19, 2007
408
© 2008 Elsevier Inc. All Rights Reserved
We retrospectively reviewed the computerized data of 3262 patients who underwent 4095 PCNL procedures from January 1995 through March 2006 at our center. Renal bleeding that was not controlled with conservative measures such as clamping of the nephrostomy tube, adequate hydration, diuretics, and 0090-4295/08/$34.00 doi:10.1016/j.urology.2007.10.033
Table 1. Patients and renal characteristics of 41 cases requiring superselective angiography Character Sex Male Female Side Right Left Renal morphology No abnormalities Hydronephrosis Pyelonephritis Renal unit Not solitary Solitary Stone burden Single Multiple Staghorn Recurrence No Yes No. of tracts Single Multiple Figure 1. Left superselective renal angiography showing a small pseudoaneurysm arising from a peripheral branch of the middle segmental artery.
hemostatic drugs, or severe bleeding leading to hemodynamic instability, was treated with transcatheter superselective renal angiography.
Technique of Embolization Experienced interventional radiologists performed all embolization procedures. The procedure started with selective renal angiography to identify the site and nature of the vascular injury. Platinum microcoils 0.035 inch (Boston Scientific, Boston, Mass) were delivered through the 6-Fr angiographic catheter (Copra II; Terumo, Osaka, Japan) for segmental arterial lesions. We used 0.018-inch helical platinum microcoils through the 3-Fr coaxial microcatheter (Target Therapeutics, Fremont, Calif) for lesions in subsegmental peripheral arteries (Fig. 1). At the end of the embolization procedure, we performed angiography to confirm complete occlusion of the injured vessel.
No. (%) 26 (63) 15 (37) 17 (41.5) 24 (58.5) 10 (24) 20 (49) 11 (27) 32 (78) 9 (22) 13 (32) 19 (46) 9 (22) 27 (66) 14 (34) 29 (71) 12 (29)
carried out in patients with serum creatinine less than 1.8 mg/dL.
Technique of DMSA Scans We obtained images 2 hours after intravenous injection of 99m Tc-DMSA (Medi-Physics, Arlington Heights, Ill) at a dose of 1.6 to 2 MBq/kg. We used a state-of-the-art triple-detector gamma camera (SMV DST.Xli; GE, Milwaukee, Wis) equipped with high-resolution collimator and applied a planar scintegraphic technique. The percent (split) radiotracer uptake by the corresponding renal unit was calculated from the computerized data. A single radiologist reviewed all images for determination of the distribution of the radioactive tracer (homogeneous or heterogeneous) and the presence of a single or multiple photopenic (cold) areas.
Statistical Analysis We compared changes in the percentage of renal uptake of the radiotracer by the corresponding kidney measured at short-term and long-term follow-up using t-test (two- tailed).
Follow-up
RESULTS
We recorded all postembolization complications. We evaluated the short-term effects of embolization after 3 months with renal ultrasonography (RUS), dimercaptosuccinic acid (DMSA) renal scan, and estimation of serum creatinine. Then, we performed regular follow-up with RUS and serum creatinine every 3 months for 1 year. After the local ethical committee approved the study protocol, patients were recruited for long-term evaluation of the morphological and functional effects of embolization on the kidney. They were clinically evaluated for new onset of hypertension, and serum creatinine was estimated. Radiological investigations included RUS and DMSA renal scan for all patients. Moreover, excretory urography (IVU) was
Of the 4095 PCNL procedures, 41 (1%) required transcatheter superselective renal angiography. Table 1 lists patients’ demographic profile and renal and stone characteristics that required embolization. The mean age was 51 ⫾ 12 years (range, 25 to 80 years). Renal angiography revealed pseudoaneurysm in 22 patients, arteriovenous fistula (AVF) in 8, and both lesions in 7 patients, whereas arterial laceration was seen in 4 patients. Vascular injuries were related to the upper, middle, and lower segmental renal vessels in 11, 6, and 22 patients, respectively, whereas injury of both the upper and lower branches was
UROLOGY 71 (3), 2008
409
encountered in 1 patient, and the remaining patient had injury of a large hilar artery. Bleeding could be controlled with superselective embolization in 38 patients (93%). We observed early postembolization complications in 6 patients. We detected perinephric hematomas in 4 patients; conservative management was successful in 3, whereas 1 patient developed perinephric abscess resulting from infection of the hematoma and was treated with percutaneous tube drain. The remaining 2 patients developed urinary leakage through the nephrostomy tract and were successfully managed with double pigtail ureteric stent for 4 weeks. Transcatheter embolization failed to control bleeding in 3 patients: 2 with large AVF and 1 with hilar vascular injury. We performed urgent exploration in all 3 patients. Deep sutures at the site of the nephrostomy tube could control bleeding in the first patient and nephrectomy was required in the second patient. The third patient died during exploration because of profuse internal hemorrhage owing to injury of a large hilar artery. Of the 38 patients, 29 had normal contralateral kidney and 9 had a solitary kidney. At 3-month follow-up, serum creatinine levels were stable in 6 patients with a solitary renal unit, whereas they were elevated in the other 3 patients from preoperative values of 0.8, 1, and 1.3 to 2.5, 3.6, and 6 mg/dL, respectively. During the follow-up period of 3, 2, and 1.5 years, none of these 3 patients required renal replacement therapy. Three months after embolization, RUS revealed complete resolution of all perinephric collections; pyelonephretic changes were present in 10 kidneys and residual nontargeted stones were detected in 6. Long-term follow-up was completed for 30 of 38 patients because 8 patients were lost to follow-up after 3 months, and hence were not included in the evaluation of long-term results. The mean follow-up period was 3.9 ⫾ 2.3 years (range, 1.4 to 9.2 years). Of the 30 patients, 18 had hypertension before PCNL and 1 of the remaining 12 developed hypertension 3 years after PCNL. However, this patient had multiple risk factors for development of essential hypertension, including obesity and hypercholesterolemia. We performed IVU in 27 patients because 3 had high serum creatinine. It showed good contrast excretion without abnormalities in the caliceal configuration in 19 renal units (70%), whereas pyelonephretic changes were observed in 6 (22%) and the remaining 2 renal units (7%) showed no contrast excretion. We detected recurrence of renal stones in 9 patients (30%); 7 of them were treated with extracorporeal shock wave lithotripsy and 2 with PCNL. Table 2 shows results of DMSA scans at 3 months and at last follow-up visit for the 30 patients who completed long-term follow-up. The most important observation was the homogeneous distribution of 99mTc-DMSA with no evidence of photopenic areas in 6 renal units (20%): 4 of them at 3-month follow-up and another 2 at the last 410
Table 2. Results of DMSA scans of corresponding kidney for 30 patients who completed long-term follow-up At 3 Months
At Last Follow-up
DMSA
No. (%)
No. (%)
Single photopenic area Multiple photopenic areas Absent photopenic areas
19 (64) 7 (23) 4 (13)
17 (57) 7 (23) 6 (20)
DMSA ⫽ dimercaptosuccinic acid. Data represent number of renal units.
follow-up scan. The mean percentage of DMSA uptake by the corresponding kidney improved from 25 ⫾ 9% at the 3-month scans to a mean value of 34 ⫾ 11% at the last follow-up scans. This improvement was statistically significant (P ⬍0.001).
COMMENTS Renal vascular injuries during PCNL are frequent, necessitating blood transfusion in 3% to 23%.2–5,9,10 Transcatheter embolization is required in 1% of patients only when simple maneuvers are insufficient to control bleeding. Percutaneous transcatheter embolization is a valuable treatment for most renal vascular injuries.11 It is a minimally invasive intervention that can control bleeding in most patients, thus saving the patient from the morbidity and even mortality that results from severe renal bleeding.12 Moreover, successful superselective embolization of the injured vessel preserves the function of the rest of the kidney parenchyma. Therefore, it is considered first-choice treatment for renal vascular injuries.5– 8 However, the embolization procedure results in an ischemic area of the parenchyma (infarction) with subsequent detrimental effects on renal function. The extent of this infarction and its effect on renal function and morphology have been reported in a few studies.7,8,13 These studies had many limitations and bias such as small number or heterogeneous groups of patients, lack of longterm follow-up, and the use of different methods to evaluate renal function. The present study includes a large homogeneous group of patients (post-PCNL vascular injury) for whom we performed the long-term evaluation of morphological and functional changes by comparing the early and late results of a single imaging study (DMSA). Estimation of serum creatinine level is a rough indicator of renal function, but it may be helpful in patients with a solitary kidney. Perini et al. estimated the likelihood of long-term detrimental effects of embolization for biopsy-related vascular injuries in transplanted kidneys by variations in serum creatinine levels before and after the procedure. They found no detrimental effect in 58% of patients.13 In our study, we observed that 33% of patients with a solitary kidney experienced postembolization deleterious effects in the form of elevation of serum creatinine levels. UROLOGY 71 (3), 2008
After intravenous injection, 99mTc-DMSA is taken up by the proximal tubular cells. Thus, high-spatial-resolution images of the renal cortex can be obtained. The cortical uptake of this radiotracer depends on renal blood flow and proximal tubular cell membrane function. Therefore, the low uptake of DMSA by an area of the renal parenchyma will be confined to a photopenic area that represents the parenchyma supplied by the embolized artery. These special characteristics of 99mTc-DMSA allow qualitative evaluation of the renal cortex morphology and quantitative assessment of split renal uptake of the radiotracer.14,15 In the present study, we performed a comparison to evaluate the early and late results of DMSA scans after superselective embolization. An important observation was the significant improvement of split renal uptake in long-term follow-up. These findings may be due to development of intrarenal collateral supply, which retransfuses the initially ischemic area and prevent total infarction from occurring. Although the renal arteries have been considered end arteries, intrarenal anastmosis exists via the perivascular plexus of segmental, interlobar, and arcuate arteries. The second reason may be the use of the superselective technique, which is associated with a smaller area of infarction.8,16 Then the infarct acts as a scar, which has the tendency to shrink with time. Poulakis et al. also observed shrinkage of the infarct area and compared the size of the nonperfused area on postembolization angiography with its size on contrast-enhancement computed tomography (CT) scans after a mean follow-up of 40 months.7 The mean size of the infarct area had decreased from 9% in early postembolization angiographic films to 5% in the long-term CT scans. Chaziioannou et al. also found a decrease in the early postembolization infarct area from a mean value of 12% to 6% after a mean follow-up of 12 months using contrast-enhancement CT.8 Another important finding in our study is the absence of photopenic areas in DMSA scans in 20% of patients. Beaujeux et al. had a similar observation and found no renal parenchymal infarction in 3 of 6 patients after superselective embolization of peripheral renal vascular lesions.17 Complete disappearance of the evidence of parenchymal infarction on short-term follow-up may result from revascularization of the embolized artery or retransfusion of this area from adjacent vessels. Such a finding in long-term follow-up may be attributed to shrinkage of a small peripheral infarct. The possibility of missing a small infarct area by using the planar technique of DMSA scan, which gives only two-dimensional images, also cannot be excluded. However, the exact cause needs to be further evaluated using three-dimensional imaging such as 99mTc-DMSA single photon emission CT (SPECT), contrast-enhancement spiral CT, and dynamic magnetic resonance imaging, or studying the hypothesis of revascularization and retransfusion in animal models. In our study we used the planar DMSA scanning UROLOGY 71 (3), 2008
technique for long-term follow-up because it has been used for early evaluation. Before the advent of the coaxial catheter, it was impossible to catheterize subsegmental branches, and embolization had to be performed more proximally, which resulted in a large area of infarction and loss of function.18 In this study and that of Poulakis et al. and Chaziioannou et al., the use of coaxial catheter and microcoils enabled superselective embolization of peripheral arterial branches sufficient to control bleeding and preserve the largest possible renal parenchyma, which was reflected on preservation of renal function.7,8 The theoretical fear of development of hypertension after renal embolization owing to release of rennin from the ischemic parenchyma was not realized, partially because of the lack of long-term follow-up of such patients or because that this did not occur. Our results and those of Beaujeux et al. showed no risk of neo-onset of hypertension after superselective embolization.17 The reasons may be the same as described before for improved function or total replacement of the infarct area by fibrous tissue not capable of rennin release.
CONCLUSIONS Superselective renal embolization is an effective treatment for post-PCNL renal vascular injuries. Short-term deleterious effects were more pronounced in patients with a solitary kidney. However, long-term follow-up showed functional and morphological improvements. References 1. Preminger GM, Assimos DG, Lingeman JE, et al: AUA Nephrolithiasis Guideline Panel Chapter 1: AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations. J Urol 173: 1991–2000, 2005. 2. El-Kenawy MR, El-Kappany HA, El-Diasty TA, et al: Percutaneous nephrolithotomy for renal stones in over 1000 patients. BJU Int 69: 470 – 475, 1992. 3. Martin X, Murat FJ, Feitosa LC, et al: Severe bleeding after nephrolithotomy: results of heperselective embolization. Eur Urol 37: 136 –139, 2000. 4. Srivastava A, Singh KJ, Suri A, et al: Vascular complications after percutaneous nephrolithotomy: are there any predictive factors? Urology 66: 38 – 40, 2005. 5. El-Nahas AR, Shokeir AA, El-Assmy AM, et al: Post-percutaneous nephrolithotomy extensive hemorrhage: a study of risk factors. J Urol 177: 576 –579, 2007. 6. Vignali C, Lonzi S, Bargellini I, et al: Vascular injuries after percutaneous renal procedures: treatment by transcatheter embolization. Eur Radiol 14: 723–729, 2004. 7. Poulakis V, Ferakis N, Becht E, et al: Treatment of renal vascular injury by transcatheter embolization: immediate and long-term effects on renal function. J Endourol 20: 405– 409, 2006. 8. Chatziioannou A, Brountzos E, Primetis E, et al: Effects of superselective embolization for renal vascular injuries on renal parenchyma and function. Eur J Vasc Endovasc Surg 28: 201–206, 2004. 9. Sacha K, Szewczyk W, and Bar K: Massive haemorrhage presenting as a complication after percutaneous nephrolithotomy (PCNL). Int Urol Nephrol 28: 315–318, 1996. 10. Galek L, Darewicz B, Werel T, et al: Hemorrhagic complications of percutaneous lithotripsy: original methods of treatment. Int Urol Nephrol 32: 231–233, 2000.
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