14.1 Peripheral Interventions

Peripheral Interventions in the Cath Lab

Peripheral vascular interventions are Domain C Tasks 5 and 6 on the CCI RCIS Detailed Test Outline — a substantial portion of the 34% Interventional Procedures domain. While coronary work dominates many cath labs, the RCIS must equally support renal artery stenting, lower-extremity revascularization, and inferior vena cava (IVC) filter placement. These procedures share core cath lab skills — sterile technique, sheath management, anticoagulation, contrast administration, and fluoroscopic imaging — but differ in anatomy, device selection, and complication profiles. RCIS items often test whether you know when each intervention is indicated, what equipment the operator needs, and how you anticipate complications before they become emergencies.

Renal Artery Interventions

Renal artery stenosis (RAS) — most commonly from atherosclerotic disease at the ostium or fibromuscular dysplasia (FMD) in younger women — causes resistant hypertension and progressive renal insufficiency. Diagnostic evaluation begins with non-invasive imaging (duplex ultrasound, CTA, MRA), but invasive renal angiography remains the reference standard when intervention is planned.

Selective renal angiography uses a JR4, Simmons, or RDC (renal double-curve) catheter advanced over a guidewire from femoral or radial access. The RCIS prepares power injectors with diluted contrast (institutional protocol, often 50% strength for renal runs), ensures hydration per renal-protection orders, and monitors creatinine trends post-procedure. Angiographic hallmarks of hemodynamically significant stenosis include >70% diameter reduction, post-stenotic dilatation, and delayed parenchymal blush.

Renal artery stenting is indicated for atherosclerotic ostial/proximal stenosis with uncontrolled hypertension, recurrent flash pulmonary edema ("flash edema" pattern), or ischemic nephropathy. FMD is treated with balloon angioplasty alone in many cases; stenting is reserved for flow-limiting dissection or residual stenosis. Device selection favors balloon-expandable stents at the ostium (radial force against aortic plaque shift) and self-expanding stents for more distal lesions.

Complications unique to renal intervention include cholesterol embolization syndrome (toe discoloration, rising creatinine 1–2 weeks post-procedure), renal artery dissection/perforation, and contrast-induced nephropathy. The RCIS role is early recognition and communication — not independent management.

Lower Extremity Revascularization

Peripheral arterial disease (PAD) affecting the aortoiliac, femoropopliteal, and infrapopliteal segments is increasingly treated in hybrid cath lab / endovascular suites. Indications range from claudication unresponsive to medical therapy to critical limb ischemia (CLI) with rest pain or tissue loss.

Iliac interventions typically use large-bore femoral access (7–9 Fr), 0.035-inch guidewires, and balloon-expandable stents (e.g., for common iliac lesions) or self-expanding stents for external iliac and long lesions. Kissing-balloon technique treats bilateral iliac disease at the aortic bifurcation — the RCIS prepares two simultaneous balloon/stent systems and coordinates inflation timing with the operator.

Femoropopliteal (SFA) disease presents unique challenges: tortuosity, calcification, and long-segment occlusions. Self-expanding nitinol stents, drug-eluting stents (DES), and drug-coated balloons (DCB) reduce restenosis compared with plain balloon angioplasty alone. The popliteal artery moves with knee flexion — stent selection must account for fracture risk in this segment.

Infrapopliteal (below-knee) intervention targets anterior tibial, posterior tibial, and peroneal arteries for CLI limb salvage. Small vessels (2.5–4 mm) require 0.014-inch wire systems, low-profile balloons, and meticulous antiplatelet regimens (dual antiplatelet therapy per operator order). The RCIS maintains pedal pulse checks documentation and prepares reperfusion catheters if thrombus is encountered.

IVC Filter Placement

IVC filters prevent pulmonary embolism (PE) when anticoagulation is contraindicated or when PE recurs despite adequate anticoagulation. They are placed infrarenal (below the renal veins) or suprarenal when infrarenal placement is impossible (prior IVC ligation, pregnant patient, gonadal vein considerations).

Retrievable (optional) filters — Bard Denali, Cook Celect Platinum, ALN — allow removal after the acute PE risk resolves, typically within 3–6 months if the filter can be safely retrieved. Permanent filters remain when retrieval is not feasible. The RCIS verifies filter inventory, delivery sheath size (often 6–12 Fr depending on filter), and IVC diameter measurements from cavography before deployment.

Cavography via pigtail catheter from femoral or jugular access defines:

• IVC diameter (oversizing filter risks migration; undersizing risks perforation)
• Renal vein location (deployment must be below lowest renal vein for infrarenal filters)
• Thrombus burden in the IVC (may alter filter choice or contraindicate placement)

Complications include filter migration, tilt, penetration of IVC wall, and DVT at the access site. Post-procedure, patients require continued surveillance imaging for retrievable filters per institutional protocol.

Stenting Fundamentals Across Peripheral Territories

Whether renal, iliac, or SFA, peripheral stenting follows shared principles the RCIS must internalize:

1. Predilation — undersized balloon opens the lesion before stent delivery
2. Stent sizing — diameter matched to reference vessel; length covers lesion with 1–2 cm margins
3. Post-dilation — high-pressure balloon optimizes stent apposition, especially in calcified lesions
4. Completion angiography — confirms TIMI/analogous runoff, no dissection, no embolization

Balloon-expandable stents (stainless steel or cobalt-chromium) provide precise deployment at fixed diameters — ideal for ostial lesions where radial strength matters. Self-expanding stents (nitinol) conform to tortuous anatomy and resist external compression — preferred for long SFA lesions and external iliac arteries.

Anticoagulation and Antiplatelet Considerations

Peripheral interventions require intraprocedural anticoagulation (heparin to ACT 250–300 seconds for most cases). Post-procedure dual antiplatelet therapy (DAPT) duration varies by lesion location and device type — the RCIS documents administered medications but does not independently prescribe. Closure devices at femoral access sites require the same hemostasis vigilance as coronary cases.

Exam Focus Points

High-yield RCIS scenarios include: identifying infrarenal vs suprarenal IVC filter placement, knowing balloon-expandable stents for ostial renal lesions, recognizing CLI as the indication for infrapopliteal intervention, and understanding retrievable filter retrieval windows. Comparison questions often test device selection by anatomy and complication recognition (cholesterol emboli after renal stenting, stent fracture in the popliteal artery).