Periprocedural Care
Preprocedural Planning
Patient selection
Renovascular disease is present in 10-40% of patients with end-stage renal disease (ESRD); these constitute the fastest-growing group of patients with ESRD. Nonselective correction of renal artery stenosis (RAS) has led to disappointing results. Most groups that compared conservative treatment with angioplasty found only modest or no beneficial effects of angioplasty on renal function and blood pressure (BP).
The CORAL (Cardiovascular Outcomes in Renal Artery Lesions) trial included 947 participants who had atherosclerotic RAS (ARAS) and either (a) systolic hypertension (HTN) while on two or more antihypertensive drugs or (b) chronic kidney disease; the participants were randomly assigned to medical therapy plus renal artery stenting or medical therapy alone. [42, 13] The investigators did not find stenting to provide significant added benefit with regard to preventing clinical events in this setting.
Patients with a high likelihood of a favorable response should be identified. [14, 43, 44] Factors that affect outcome include the following:
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Severity of RAS
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Procedure used to treat RAS (eg, antihypertensive drugs, angioplasty with or without stents, surgery)
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Nephrotoxicity to radiologic contrast materials
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Atheroembolism [45]
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Underlying renal disease forestalling a favorable response in renal function or BP, even after the successful correction of RAS (most important)
Renal resistance may be evaluated by using Doppler ultrasonography (US) or captopril scintigraphy to determine whether patients may or may not respond to intervention. Each factor must be considered before the correction of RAS to achieve satisfactory results in improving renal function and BP.
Preprocedural evaluation
Diagnostic studies for renovascular disease include the following:
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Rapid-sequence intravenous pyelography (IVP) - This test has a sensitivity of 74.5% and a specificity of 86.2%, but limited sensitivity for bilateral or branch RAS; the false-positive rate of 12% in patients with essential HTN [46]
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Test of the renin ratio in the renal vein - This test has a sensitivity of 80% and a specificity of 62%; use of sodium depletion, hydralazine, nifedipine, and captopril may enhance asymmetric response and increase sensitivity without affecting specificity; renal cysts, pyelonephritis, and ureteral obstruction may increase the asymmetry of renin secretion [47]
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Radionuclide imaging - This test has a sensitivity and specificity of approximately 95% with use of captopril; addition of furosemide may increase sensitivity; severe renal insufficiency and the presence of bilateral RAS reduce its accuracy [48]
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Renal artery duplex US (RADUS) - This test has a sensitivity of approximately 98% (as compared with arteriography) and a specificity of 98%, as well as a positive predictive value of 99% and a negative predictive value of 97% [49] ; drawbacks are that it is technician-dependent, it is not universally available, and as many as 10% of patients cannot be imaged because of body habitus
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Magnetic resonance angiography (MRA) - This is likely to be the test of choice, with a sensitivity of nearly 100% and a specificity of nearly 90% [50] ; drawbacks are that it is nonportable and it cannot be used in patients with implanted devices, metal artifacts, or claustrophobia or in patients of certain size and weight
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Spiral (multisection) computed tomography (CT) - Sensitivity and specificity remain to be determined
Media Gallery
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Renal artery stenosis in patient with medically refractory renovascular hypertension.
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Percutaneous transluminal angioplasty.
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Renal arteriogram obtained after renal percutaneous transluminal angioplasty.
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Percutaneous transluminal renal angioplasty in middle-aged woman with malignant renovascular hypertension. Preprocedural right renal arteriogram was obtained after sterile preparation and draping of patient, conscious sedation, infiltration of local anesthetic (lidocaine 1% or 2% solution) at femoral access site, placement of arterial sheath in femoral artery, and advancement of renal guide catheter over 0.035-in. guide wire under fluoroscopic guidance. After tip of guide catheter is positioned at ostium of renal artery, angiogram (as shown here) is obtained. After guide wire is removed, proximal end of catheter is connected to manifold, and 4-8 mL of contrast is manually injected during cineangiographic recording. Once obtained, image may be played over and over in loop, or particular frame may be saved for review during angioplasty. Intravenous antithrombotic agent, usually heparin, is administered before clinician proceeds with angioplasty. Patient's activated clotting time is monitored.
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Guide wire (0.018-in.) is advanced through 6F renal guide across ostial right renal stenosis. Small torque device is used over proximal segment of guide wire for steering, while small terminal bend is created by hand over distal end of guide wire before it is introduced into guide catheter. Passage of guide wire is monitored by using fluoroscopy and injections of small amounts of contrast agent. Occasionally, combination of torque and forward pressure is required to cross lesion. In addition, in tight lesions, balloon catheter is sometimes advanced and used as support for passage of guide wire.
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Balloon (6 mm × 18 mm) is positioned across lesion by carefully advancing it over guide wire. Balloon is prepared before it is loaded over guide wire by connecting its proximal balloon port to inflating device that contains half-and-half solution of contrast agent and sterile saline and then by drawing negative pressure to extrude any air bubbles. Inflating device is left in negative pressure while balloon is advanced with one hand and guide wire is held with the other. Balloon is advanced beyond distal end of guide catheter, which is gently pulled back, and balloon is straddled across stenosed segment. Small amount of contrast agent is injected to confirm proper positioning of balloon.
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Balloon is inflated by increasing pressure with inflation device to several atmospheres of pressure (usually 4-8 bars, or 400-800 kPa). Mixed solution of contrast agent and saline in inflation device gradually moves into balloon. As balloon expands, it becomes visible under fluoroscopy, as shown. Balloon is held up for several seconds to apply circumferential pressure on stenosed arterial segment, then deflated and gradually pulled back into guide catheter.
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Angiogram obtained after percutaneous transluminal angioplasty and after balloon catheter is removed, but while guide wire is still retained, shows increased luminal diameter at stenotic segment. However, segment appears to be at least 50% narrowed. Flow into renal artery from aorta is increased. Vascular wall shows no clear dissection. No filling defect (which may represent clot) is visible. Distal flow into branches of right renal artery is brisk, with good nephrogram.
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Stent-balloon catheter is prepared in manner similar to balloon catheter; however, before it is inserted into guide catheter, no negative pressure is created. Stent-balloon catheter is then advanced over guide wire through guide catheter beyond distal opening and across lesion. Stent is positioned over lesion by confirming its placement with injection of small amount of contrast material through guide. Guide catheter is pulled back on wire slightly to allow proximal edge of stent to be slightly in aorta. Before stent balloon is inflated, guide catheter is pushed upward to straighten stent and wire in proximal portion of renal artery. Stent is then deployed by first creating negative pressure in stent balloon and then inflating it by injecting contrast agent–saline solution through inflation device. Stent is left inflated for several seconds at 5-10 bars (500-1000 kPa) of pressure. Balloon is then deflated and withdrawn while guide wire is retained across lesion, and guide catheter is slightly advanced into stent.
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Fluoroscopic image shows guide wire still lying across stented segment. Stent shadow is visible in proximal portion of right renal artery, and it appears well expanded.
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Last, guide wire is withdrawn after absence of flap, dissection, or filling defect is confirmed. Poststenting angiogram shows 0% residual stenosis in proximal renal artery. Guide catheter is finally withdrawn.
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Preangioplasty angiogram obtained in young woman with malignant hypertension shows tight stenosis in middle segment of right renal artery. Its appearance is consistent with that of fibromuscular dysplasia (FMD), for which angioplasty is procedure of choice and for which stenting is usually not indicated. Intra-arterial nitroglycerin, 300 mcg, was given without any change in appearance of stenosis (which differentiates it from spasm). In general, intra-arterial nitroglycerin injection is not necessary to differentiate it from FMD that has been demonstrated on prior abdominal aortogram.
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Fluoroscopic image shows inflated percutaneous transluminal angioplasty (PTA) balloon in midright renal artery over guide wire. In this case, Judkins right 4 (JR4) guide was used to access right renal artery via right femoral approach. Balloon was left inflated for several seconds, then deflated and pulled out. Additional intra-arterial nitroglycerin was infused.
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Angiogram obtained after percutaneous transluminal angioplasty and after balloon catheter was removed shows good result with residual stenosis of < 20% at previously stenosed site. Flow into renal artery from aorta is increased. Vascular wall shows no clear dissection. No filling defect (which may represent clot) is visible. Distal flow into branches of right renal artery is brisk, with good nephrogram.
of
14
Tables
- Table 1. Success Rates of Percutaneous Transluminal Renal Angioplasty (PTRA) in Renal Artery Stenosis (RAS) Caused by Atherosclerosis (80% of RAS) and Fibromuscular Dysplasia (FMD; 20% of RAS) [27, 28]
- Table 2. Success Rates of Percutaneous Transluminal Renal Angioplasty (PTRA) in Renal Artery Stenosis (RAS) Caused by Atherosclerosis (80% of RAS) [23, 31, 32]
- Table 3. Natural History: Progression of Medically Treated Renal Artery Stenosis [34]
- Table 4. Effect of Renal Stenting on Serum Creatinine Level [28]
Table 1. Success Rates of Percutaneous Transluminal Renal Angioplasty (PTRA) in Renal Artery Stenosis (RAS) Caused by Atherosclerosis (80% of RAS) and Fibromuscular Dysplasia (FMD; 20% of RAS)
[27, 28]
Outcome |
Atherosclerotic RAS, % |
RAS Due to FMD, % |
Primary success |
85 |
89 |
Hypertension cured |
19 |
41 |
Hypertension improved |
61 |
44 |
Restenosis |
50 |
15 |
Table 2. Success Rates of Percutaneous Transluminal Renal Angioplasty (PTRA) in Renal Artery Stenosis (RAS) Caused by Atherosclerosis (80% of RAS)
[23, 31, 32]
Intervention |
Success Rate, % |
Restenosis Rate, % |
PTRA |
85 |
50 |
Renal stenting |
100 |
25 |
Table 3. Natural History: Progression of Medically Treated Renal Artery Stenosis
[34]
Outcome |
Rate, % |
Decrease in glomerular filtration rate |
37 |
Increase in creatinine level |
20 |
Decrease in renal size |
35 |
Table 4. Effect of Renal Stenting on Serum Creatinine Level
[28]
Change in Creatinine Level |
Rate, % |
Improved |
29 |
None |
67 |
Worsened |
4 |
