Cath Lab Digest

Introduction
Distal renal artery perforation during renal arterial stenting with a guidewire is an uncommon but potentially fatal complication.¹ Although guidewire perforation leading to subcapsular or perirenal hematoma may be successfully managed conservatively or by embolotherapy, surgical intervention is occasionally required.^2,3 Spontaneous renal subcapsular hemorrhage (SRSCH) can occur in patients with an underlying renal mass or in those with a bleeding diathesis or on anticoagulant medication.

Case Report
Case 1.
A 65-year-old woman with difficult to control hypertension and right renal artery stenosis (revealed by computed tomography) was referred for elective renal artery stenting. The serum creatinine was 197µmol/l, and international normalized ratio (INR) was 1.2.

Following selective cannulation of the right renal artery with a 5-Fr Simmons 1 catheter (Cordis, Miami Lakes, Florida), a 7-Fr Brite tip sheath (Cordis) was advanced through the stenosis over a 0.035” Rosen guidewire (Cook, Bloomington, Indiana). A 6mm x 14mm stent (Genesis, Cordis) was deployed over 0.018' (V-18, Boston Scientific, Natick Massachusetts) guidewire. Check angiography demonstrated adequate restoration of the renal arterial lumen. Intra-arterial administration of 3000U of Heparin was administered during the procedure. The procedure was uneventful, and following puncture site closure with a 6-Fr Angioseal (St Jude Medical), the patient was immediately commenced on an intravenous heparin infusion at the rate of 750U/hr.

At two hours post procedure, the patient developed a tender, right-flank swelling and hypotension associated with a drop in the blood hematocrit (Hb from 102g/l to 83g/l). Retroperitoneal hemorrhage related to guidewire perforation was suspected. The angiographic images were reviewed but none of the images demonstrated guidewire extension beyond the lateral margin of the right kidney. CT of the abdomen demonstrated a large subcapsular hematoma with extension into perinephric and pararenal spaces. On the arterial phase images, active extravasation of contrast from the posterior aspect of the midpole cortex of the right kidney was evident (Figure 1). The site of extravasation corresponded closely to the site of 0.018” guidewire placement at the time of renal arterial stent placement. Smaller areas of active contrast extravasation were also identified elsewhere over the renal cortical surface.

Catheter angiography confirmed the CT findings of multiple areas of contrast extravasation, the most active corresponding with midpole bleeding site identified on the arterial phase (Figure 2). Embolization of the bleeding artery in the midpole was performed using PVA particles. Check angiography confirmed cessation of extravasation from the embolized branch although there were noted to be a number of small, persistent areas of contrast extravasation in the periphery of the mid- and lower-pole regions. The feeding vessels to the bleeding sites were considered too small and ill defined to embolize. Reversal of anticoagulation was chosen in favor of more proximal embolization in order to preserve as much functional renal tissue as possible.

Over the next 12 hours, the patient received 3 units of blood with no proportionate increase in the hematocrit (79 to 83g/l). A repeat angiogram was performed with embolization of two further actively bleeding lower pole cortical vessels (MWCE-18-1.0-0-Hilal, Cook). Following the repeat embolization, the patient became hemodynamically stable and further recovery was uneventful.

Case 2.
A 70-year-old patient on warfarin therapy for cardiac arrhythmias presented to the Emergency Department with a history of acute left flank pain. The patient’s INR was 7.3 at the time of presentation. Although hemodynamically stable at the time of presentation, a significant fall in the patient’s blood pressure occurred over the next hour (BP 92/62 mm Hg). He was transfused with 2 units of FFP and an urgent abdominal CT scan ordered. This demonstrated a large left subcapsular hematoma extending into the perinephric and paranephric spaces. No underlying renal mass was identified. Arterial phase images demonstrated multiple sites of active contrast extravasation from the renal cortical surface (Figure 3).

A subsequent catheter angiogram confirmed the presence of multiple sites of contrast extravasation (Figures 4A and 4B). The most prominent bleeding site, situated in the upper pole of the kidney, was embolized with coils (MWCE-18-1.0-0-HILAL, Tornado Embolization Coils, Cook). Following the embolization procedure and normalization of his INR, the patient recovered uneventfully.

Discussion
Guidewire perforation of a distal renal artery branch is a rare but potentially serious complication of renal artery stent placement.³ A fatal case of guidewire perforation following renal arterial stenting has been reported by Axelrod et al.¹