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SPONTANEOUS REGRESSION OF A RENAL ARTERIOVENOUS MALFORMATION
0022-5347/00/1631-0232/0 THE JOURNAL OF UROLOGY® Copyright © 2000 by AMERICAN UROLOGICAL ASSOCIATION, INC.®
Vol. 163, 232–233, January 2000 Printed in U.S.A.
SPONTANEOUS REGRESSION OF A RENAL ARTERIOVENOUS MALFORMATION TAKAHIRO INOUE*
AND
TAKAYUKI HASHIMURA
From the Department of Urology, Himeji National Hospital, Himeji, Japan KEY WORDS: renal artery, arteriovenous malformations, kidney
A renal arteriovenous fistula is an anomalous connection between the arterial and venous systems. An acquired type of arteriovenous malformation, especially after percutaneous renal biopsy, often resolves within a few months. However, most symptomatic congenital arteriovenous malformations require surgical or interventional therapy and their natural history remains unknown.1 We report a case of spontaneous regression of a congenital type of arteriovenous malformation.
informed of the risk of embolization, no further treatment was given. On October 27, although the patient had been asymptomatic, we performed renal arteriography to embolize the malformation and prevent future recurrence. We found no evidence of the arteriovenous malformation (part B of figure) and she was free of hematuria.
DISCUSSION CASE REPORT
A 26-year-old woman presented in March 1996 with right flank pain and gross hematuria, followed by bladder tamponade. She was in the first trimester of an uncomplicated second pregnancy. Ultrasonography revealed slight right hydronephrosis. Cystoscopy demonstrated bleeding through the right ureteral orifice. Symptoms subsided after treatment with tranexamic acid. Gross hematuria recurred in the last trimester but resolved after 7 days. Excretory urography performed postpartum showed no apparent abnormality. On March 1, 1998 massive hematuria recurred with bladder tamponade, and the patient was hospitalized. Since renal vascular disease was strongly suspected, angiography was performed on March 6, which revealed early venous return of the right renal vein and diagnosis was right renal arteriovenous malformation (part A of figure). Because symptoms had resolved at angiography and the patient had not been Accepted for publication August 20, 1999. * Requests for reprints: Department of Urology, Aichi Cancer Center, 1–1 Kanokoden, Chikusaku, Nagoya 464-8681, Japan.
Several cases of spontaneous regression of cerebral and dural arteriovenous malformation have been reported.2 To our knowledge only 1 case of spontaneous regression of intrarenal arteriovenous malformation has been reported in the literature.3 The exact mechanism of spontaneous regression of intracranial arteriovenous malformation remains unknown. However, there are several hypotheses. Intracranial hemorrhage or hematoma may compress the lesion, promoting thrombosis in the vessels of malformation.2 Associated vasospasm and edema might also contribute to the reduction of blood flow to the arteriovenous malformation potentiating thrombosis.2 Increased blood turbulence and alterations in flow dynamics might be the reason for subacute or gradual thrombosis, which might lead to regression of intracranial arteriovenous malformation. Regardless of the mechanism that triggers the spontaneous regression, it has been suggested that this phenomenon is more likely to occur when the arteriovenous malformation is small with a single proper feeder.
A, right renal arteriogram reveals arteriovenous malformation. B, right renal arteriogram 7 months after initial examination shows disappearance of arteriovenous malformation. 232
SPONTANEOUS REGRESSION OF RENAL ARTERIOVENOUS MALFORMATION
In our case arteriovenous malformation was small and the 2 episodes of severe macroscopic hematuria that resulted in renal pelvic tamponade might have led to thrombosis in the small vessels of arteriovenous malformation.3 Selective catheterization during arteriography might have damaged the fragile vessels of arteriovenous malformation, which resulted in the formation of thrombosis. In conclusion, spontaneous regression of a small intrarenal arteriovenous malformation can occur if massive hematuria resolves without any complication.
233
REFERENCES
1. Crotty, K. L., Orihuela, E. and Warren, M. M.: Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas. J Urol, 150: 1355, 1993. 2. Pasqualin, A., Vivenza, C., Rosta, L. et al: Spontaneous disappearance of intracranial arterio-venous malformations. Acta Neurochir (Wein), 76: 50, 1985. 3. Yoshiki, T., Kondo, M. and Kitayama, T.: Spontaneous regression of an intrarenal arteriovenous malformation. J Urol, 137: 725, 1987.
Vol. 163, 232–233, January 2000 Printed in U.S.A.
SPONTANEOUS REGRESSION OF A RENAL ARTERIOVENOUS MALFORMATION TAKAHIRO INOUE*
AND
TAKAYUKI HASHIMURA
From the Department of Urology, Himeji National Hospital, Himeji, Japan KEY WORDS: renal artery, arteriovenous malformations, kidney
A renal arteriovenous fistula is an anomalous connection between the arterial and venous systems. An acquired type of arteriovenous malformation, especially after percutaneous renal biopsy, often resolves within a few months. However, most symptomatic congenital arteriovenous malformations require surgical or interventional therapy and their natural history remains unknown.1 We report a case of spontaneous regression of a congenital type of arteriovenous malformation.
informed of the risk of embolization, no further treatment was given. On October 27, although the patient had been asymptomatic, we performed renal arteriography to embolize the malformation and prevent future recurrence. We found no evidence of the arteriovenous malformation (part B of figure) and she was free of hematuria.
DISCUSSION CASE REPORT
A 26-year-old woman presented in March 1996 with right flank pain and gross hematuria, followed by bladder tamponade. She was in the first trimester of an uncomplicated second pregnancy. Ultrasonography revealed slight right hydronephrosis. Cystoscopy demonstrated bleeding through the right ureteral orifice. Symptoms subsided after treatment with tranexamic acid. Gross hematuria recurred in the last trimester but resolved after 7 days. Excretory urography performed postpartum showed no apparent abnormality. On March 1, 1998 massive hematuria recurred with bladder tamponade, and the patient was hospitalized. Since renal vascular disease was strongly suspected, angiography was performed on March 6, which revealed early venous return of the right renal vein and diagnosis was right renal arteriovenous malformation (part A of figure). Because symptoms had resolved at angiography and the patient had not been Accepted for publication August 20, 1999. * Requests for reprints: Department of Urology, Aichi Cancer Center, 1–1 Kanokoden, Chikusaku, Nagoya 464-8681, Japan.
Several cases of spontaneous regression of cerebral and dural arteriovenous malformation have been reported.2 To our knowledge only 1 case of spontaneous regression of intrarenal arteriovenous malformation has been reported in the literature.3 The exact mechanism of spontaneous regression of intracranial arteriovenous malformation remains unknown. However, there are several hypotheses. Intracranial hemorrhage or hematoma may compress the lesion, promoting thrombosis in the vessels of malformation.2 Associated vasospasm and edema might also contribute to the reduction of blood flow to the arteriovenous malformation potentiating thrombosis.2 Increased blood turbulence and alterations in flow dynamics might be the reason for subacute or gradual thrombosis, which might lead to regression of intracranial arteriovenous malformation. Regardless of the mechanism that triggers the spontaneous regression, it has been suggested that this phenomenon is more likely to occur when the arteriovenous malformation is small with a single proper feeder.
A, right renal arteriogram reveals arteriovenous malformation. B, right renal arteriogram 7 months after initial examination shows disappearance of arteriovenous malformation. 232
SPONTANEOUS REGRESSION OF RENAL ARTERIOVENOUS MALFORMATION
In our case arteriovenous malformation was small and the 2 episodes of severe macroscopic hematuria that resulted in renal pelvic tamponade might have led to thrombosis in the small vessels of arteriovenous malformation.3 Selective catheterization during arteriography might have damaged the fragile vessels of arteriovenous malformation, which resulted in the formation of thrombosis. In conclusion, spontaneous regression of a small intrarenal arteriovenous malformation can occur if massive hematuria resolves without any complication.
233
REFERENCES
1. Crotty, K. L., Orihuela, E. and Warren, M. M.: Recent advances in the diagnosis and treatment of renal arteriovenous malformations and fistulas. J Urol, 150: 1355, 1993. 2. Pasqualin, A., Vivenza, C., Rosta, L. et al: Spontaneous disappearance of intracranial arterio-venous malformations. Acta Neurochir (Wein), 76: 50, 1985. 3. Yoshiki, T., Kondo, M. and Kitayama, T.: Spontaneous regression of an intrarenal arteriovenous malformation. J Urol, 137: 725, 1987.