INTERVENTIONAL RADIOLOGY IN THE MANAGEMENT OF COMPLICATIONS OF RENAL TRANSPLANTATION
Sundeep J Punamiya
Surgical complications following renal transplantation are presently uncommon, with re.nements in operative techniques
and perioperative care. However, when they do occur, they can pose a significant therapeutic problem. Prompt diagnosis and timely treatment are essential in preventing loss of allograft and in reducing associated morbidity. Reparative
surgery was the mainstay in treating urological and vascular complications, but has been replaced by interventional radiological (IR) techniques due to equivalent success rates and signi.cantly lower morbidity. This article will discuss the major role played by IR in some of the common complications following transplant surgery.
1. Management of urinary obstruction and leaks
Majority of urological complications encountered after renal transplantation are ureteral obstructions and leaks, seen to occur with an incidence of 2-10%.1-4 Patients usually present with impaired renal function, suggested by elevated levels of serum creatinine. The initial diagnosis is established with an ultrasound examination and/or a nuclear scan, and con.rmed with an antegrade pyelogram. If obstruction or leakage is identi.ed, treatment can then be initiated with a percutaneous nephrostomy (PCN), followed by antegrade ureteral stenting. The two procedures are usually done at different sessions to allow for reduction in post-nephrostomy haematuria prior to placement of ureteral stent. This would reduce the risk of stent occlusion by blood clots. It is equally important to plan the antegrade stent placement at the earliest to minimize the duration of PCN, as there are problems related to prolonged external drainage, such as infection
in the immunocompromised patient, catheter displacement and discomfort of an external catheter.5-7 The ureteroneocystostomy anastomosis is the commonest site of ureteric obstruction and leak, and is the site that responds best to stent placement.2,4,8,9
Obstructions can be early (< 3 months) or late (> 3 months). Early obstructions are thought to occur from mechanical causes such as blood clots, calculi, anastomotic oedema, ischaemic necrosis, kinks and creation of a restricting submucosal tunnel.9 Majority of these early obstructions are more transient and are likely to resolve spontaneously,
during which time the indwelling ureteral stent maintains its patency. Once the stent is removed, there is less likelihood of recurrence. (Fig. 1)
Late obstructions occur as a result of .brosis related to ureteric ischaemia, and is much more resistant to percutaneous treatment. Even after adequate dilatation and stent placement, the obstruction is very likely to recur from elastic recoil of the periureteral .brosis, once the stent is removed.10
Leaks are usually the result of ureteral necrosis due to rejection or vascular ischaemia. It is important to diagnose this problem early as the urinary leak can lead to severe infection and life-threatening sepsis in the immunocompromised patient. Treatment involves the introduction of a PCN for urinary
Fig. 1c :34-year-old male presenting with rising serum creatinine few months following transplantation. (a) Antegrade
pyelogram revealing obstruction at the pelviureteric junction. A pigtail PCN catheter was inserted. (b) Balloon dilatation of the pelviureteric junctional narrowing. (c) Pyelogram after placement of ureteray diversion, followed by placement of a ureteral
diversion, followed by placement of a ureteral stent. This permits healing of the leak site, subsequent to which the stent can be removed. (Fig. 2) The overall success for percutaneous treatment for ureteral obstructions and leaks is between
40-78%, and is associated with an extremely low rate of major complications.4,6,9-12 Surgical repair is associated with much higher morbidity and mortality. In one large series comparing percutaneous stent placement and surgery, 100%
graft survival was noted in patients treated with stent, whilst 87% graft survival was seen in patients treated by surgery.4 The mortality and graft failure rates increase further with every subsequent surgery. In another large series, the survival rates in patients with a functioning graft after successful surgical repair dropped from 62.5% for the first repeat
surgery, to 41% and 20% for the second and third repeat operations respectively.1 Surgery would thus be recommended only after failure of percutaneous therapy.
2. Management of transplant renal artery stenosis (TRAS)
The most common vascular complication of renal transplantation is renal artery stenosis, seen in 1-23% of patients.13 The arterial narrowing generally occurs at the site of anastomosis of the donor artery to the native artery; narrowing at the
distal donor artery or the native proximal iliac artery may also be responsible. The patient typically presents with refractory hypertension and/or graft dysfunction. This complication is most commonly diagnosed with a Doppler ultrasound or MR angiography. Treatment of TRAS is possible with surgery or angioplasty. Surgical correction of TRAS has a 66-90% initial success rate, and one series have reported a 12% recurrence rate.14 However, surgical
therapy is not favoured due to the technical difficulty of re-operation, risk of allograft loss, ureteral injury and surgical mortality. Endovascular treatment of TRAS has gained prominence, since the results are equally gratifying, with far lower morbidity.14-
3. Management of intra renal vascular injury
Renal biopsy is critical in evaluation of graft dysfunction and treatment response. Vascular injury, in the form of arteriovenous .stula, pseudoaneurysm and arteriocalyceal fistula, is a well-recognized and feared complication of percutaneous biopsy. Spontaneous resolution of these lesions is known to occur in majority of cases. However, they may
persist or grow in at least 30% cases, manifesting as secondary hypertension, worsening of renal dysfunction, immediate or delayed haematuria or urinary obstruction from blood clots.18- All this ultimately could lead to loss of allograft.
Endovascular treatment involving embolisation of the injured vessel has been used with varying degree of success. (Fig. 5) The largest and latest series have reported a technical success rate of 95% and clinical success in 88% of cases,18 and have recommended an aggressive approach to embolising vascular lesions that appear following biopsy. Catheter technology has advanced signi.cantly, which now allows superselective placement of embolic material into the interlobar arteries and beyond. This minimizes the risk of significant parenchymal loss when embolising the end-arteries of the kidneys. (Fig. 6) The choice of embolic material is equally important, with coils being most preferred; particulate material such as gelfoam and polyvinyl alcohol that were used in earlier days could re.ux and cause infarction of a wider area, losing signi.cant allograft function.
Interventional radiological procedures have proved to be extremely efficacious and safe in treating iatrogenic and surgical complications following renal transplantation. It has become the procedure of choice in the management of urinary obstruction and leaks, renal artery stenosis, perigraft collections, and in treating vascular injuries. Surgery, once considered the only viable option, is now reserved for cases where IR therapy has failed. Even in patients who are not ideally suited for a reparative IR procedure and are too sick to undergo surgical revision, IR can provide relief till the patient can be considered fit for re-operation.
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CORONARY HEART DISEASE RISK FACTORS : KNOWN AND THE LESS KNOWN
The deadly lipid tetrad of high triglycerides, low HDL, small dense LDL and elevated Lp(a) along with high homocysteine levels explains epidemic of CHD in Indians.
Moreover, moderate and intermediate hyperhomocysteinaemia is present in 12% to 47% of patients with coronary, cerebral, or peripheral arterial occlusive disese.
The recognition that as many as 30-50% of patients with established CHD lack the traditional risk factors has led to the search for additional risk factors that may predispose individuals to CHD.
ME Yeolekar, JAPI, 2003; 51 : 945-46.
ADDING METHYLXANTHINES TO STANDARD COPD TREATMENT IS NOT BENEFICIAL
Methylxanthines do not confer any bene.t on lung function and symptoms in patients with exacerbations of chronic obstructive pulmonary disease (COPD) at standard levels of significance. In a meta-analysis of four randomised trials comprising 169 patients. Barr and colleagues found that changes in lung function, clinical outcomes, and self rated symptom scores were not signi.cantly different between methylxanthine and placebo groups, but signi.cantly more adverse events of nausea and vomiting occurred in patients.
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