10.1 Balloon Angioplasty & Stent Platforms

10.1 Balloon Angioplasty & Stent Platforms

Quick Answer: Percutaneous coronary intervention (PCI) begins with balloon angioplasty to crack and displace atherosclerotic plaque, but stents are required in most cases to prevent elastic recoil and flow-limiting dissection. Drug-eluting stents (DES) add an antiproliferative drug and polymer to the metal scaffold, dramatically lowering restenosis compared with bare-metal stents (BMS). RCIS staff must understand sizing (reference vessel diameter and lesion length), deployment technique (position, pressure, angiographic check), and how to assist with contemporary DES platforms used in modern labs.

Balloon Angioplasty: What the Balloon Actually Does

Plain old balloon angioplasty (POBA) uses a non-compliant or semi-compliant balloon inflated within the stenosis to fracture plaque, remodel the vessel wall, and enlarge the luminal diameter. Inflation is performed at controlled atmospheres (atm) while the team watches angiographically for waist resolution, dissection flaps, and slow-flow phenomena.

POBA alone leaves two problems that drove stent adoption:

1. Elastic recoil — the vessel springs partially back after deflation.
2. Flow-limiting dissection — intimal tears can create a flap that compromises antegrade flow.

For RCIS support, balloon work means verifying balloon diameter matches reference vessel size, confirming radiopaque markers straddle the lesion before inflation, and having stent inventory and IVUS/OCT readiness if the result is suboptimal. Always note inflation pressure and duration in the record—they matter if a vessel suddenly closes.

Bare-Metal Stents Versus Drug-Eluting Stents

A bare-metal stent (BMS) is a metallic scaffold that tacks dissection and prevents recoil. BMS remain appropriate in select settings (some bifurcations, patients where prolonged DAPT is impossible, certain SVG interventions per lab protocol), but in-stent restenosis from neointimal hyperplasia limits their routine use in native coronaries.

A drug-eluting stent (DES) adds:

Limus-class agents (sirolimus and derivatives) dominate contemporary DES: everolimus, zotarolimus, and biolimus A9 are the agents RCIS candidates most often encounter on inventory labels.

Contemporary DES Platform Examples

Exact hospital formularies vary, but CCI-relevant platform families include:

• Xience / XIENCE Skypoint (Abbott) — cobalt-chromium platform with everolimus and durable polymer; among the most widely implanted DES globally.
• Promus Element / Synergy family (Boston Scientific) — platinum-chromium platforms; Synergy uses everolimus with a bioabsorbable PLGA polymer on the abluminal surface (polymer-free abluminal metal after absorption).
• Resolute Onyx / Integrity (Medtronic) — cobalt or platinum-chromium platforms with zotarolimus and durable polymer designed for deliverability in tortuous vessels.
• Orsiro (Biotronik) — cobalt-chromium stent with sirolimus, bioabsorbable poly-L-lactic acid (PLLA) polymer, marketed for thin-strut deliverability.

RCIS does not choose the stent—that is physician decision—but you open the correct size, inspect expiry and integrity, prime and flush the delivery system per IFU, and capture lot numbers for implant registries.

DES Concepts RCIS Must Know

Dual antiplatelet therapy (DAPT) duration after DES is a medical decision, yet RCIS staff field patient questions. DES reduces restenosis but requires platelet inhibition while endothelialization completes; premature DAPT stop raises stent thrombosis risk—a cath lab emergency.

Stent thrombosis presents as acute closure with chest pain and ST changes; support includes activating the code team, preparing GP IIb/IIIa agents or cangrelor per protocol, and readying aspiration catheters and repeat angiography.

Polymer considerations: durable polymer DES have long track records; bioabsorbable polymer and polymer-free abluminal designs aim to lower chronic inflammation. Exam items may contrast platforms—focus on drug name + platform metal + polymer type.

Deliverability features (thin struts, low crossing profile, flexible connectors) matter when the physician struggles in tortuous or calcified anatomy—have extra support wire and lower-profile DES available per lab matrix.

Stent Sizing: Diameter and Length

Correct sizing balances adequate expansion against edge dissection and geographic miss.

Diameter

Reference vessel diameter (RVD) is estimated by visual angiography or measured with quantitative coronary angiography (QCA), IVUS, or OCT. Stent diameter is typically chosen at or slightly below RVD for most lesions; undersized stents fail to appose the wall; oversized stents risk edge dissection and perforation.

RCIS assists by confirming the stent label diameter matches the verbal order before the back table opens the package.

Length

Stent length must cover the lesion with healthy landing zones proximally and distally—commonly 2–3 mm margins beyond angiographic disease unless imaging defines otherwise. When lesion length exceeds one stent, overlap technique (typically 2–3 mm for same-diameter DES) prevents gaps; document multiple implant serial numbers.

Stent/post-dilatation balloon compatibility: post-dilatation balloons should not exceed stent inner diameter ratings in the IFU; RCIS verifies NC balloon size when ordered after deployment.

Deployment Workflow

A typical DES deployment sequence:

1. Lesion crossed with guidewire; predilation if needed (see Section 10.2).
2. Stent crimped on delivery catheter advanced over wire; radiopaque markers aligned with lesion.
3. Stent positioned with tip parked safely; physician confirms proximal/distal markers relative to branch and disease.
4. Deployment inflation at manufacturer-specified pressure (often ≥11–14 atm depending on platform) until balloon waist resolves; maintain pressure per IFU.
5. Deflate slowly, pull balloon while watching for stent migration (rare with modern crimping).
6. Angiographic result: TIMI flow, dissection at edges, apposition concerns.
7. Post-dilation with non-compliant balloon at high pressure if under-expanded or under-sized visually; IVUS/OCT when ordered.

RCIS responsibilities: flush the stent lumen, prevent air embolism, hold catheter hub during exchanges, monitor hemodynamics and ECG for ischemia, and verbalize timer requests during prolonged inflation.

Common Deployment Pitfalls

• Geographic miss — stent placed short of disease; requires overlap stent or bailout.
• Under-expansion — especially in calcified lesions; may need high-pressure NC post-dilatation or atherectomy first.
• Edge dissection — may need additional stent or balloon touch-up.
• Air embolism — catastrophic; meticulous flushing prevents it.

Balloon Types in PCI Support

Know rated burst pressure and RBP warnings—never exceed IFU limits even if the physician asks without checking.

Documentation and Registries

Record stent manufacturer, model, diameter, length, lot/UDI, deployment pressure, and number of stents. Many labs participate in NCDR CathPCI—incomplete implant logs trigger audit findings.

Official and Professional Resources

• ACC/AHA/SCAI revascularization guidelines — DES class recommendations and DAPT frameworks
• Manufacturer IFUs for Xience, Synergy, Resolute, Orsiro — deployment pressures and sizing charts
• CCI RCIS examination matrix — interventional equipment and PCI support tasks

Balloon and stent fundamentals are the daily language of the interventional lab. When you can translate RVD, stent length margins, deployment pressure, and DES drug/platform pairs into correct equipment action, you function as a true RCIS-level PCI partner—not merely a circulator.