10.2 Coronary Wiring, Lesion Prep & Flow Grades

10.2 Coronary Wiring, Lesion Prep & Flow Grades

Quick Answer: Successful PCI depends on crossing the lesion with an appropriate guidewire, preparing the vessel so stents deliver and expand, and grading flow and thrombus with standardized TIMI scales. RCIS specialists set up wires and prep devices, monitor for ischemia during wiring, and recognize TIMI 0–3 flow and TIMI thrombus 0–5 descriptions the team uses in STEMI and complex PCI.

Coronary Guidewires: Selection and Support

The guidewire is the rail for balloons, stents, IVUS catheters, and microcatheters. Wire choice affects crossing success, device deliverability, and safety (perforation risk with stiff tips).

Core Wire Properties

Workhorse wires (moderate tip load, versatile coating) handle most routine PCI. Extra-support wires improve stent delivery when the lesion is calcified or the vessel is tortuous. Dedicated CTO or chronic-total-occlusion wires (very high tip load, tapered tips, polymer jackets) belong in advanced sets—RCIS ensures sterile wire exchange and pinch-wipe technique to avoid losing wire position.

Wiring Technique Essentials

1. Advance wire tip under fluoroscopy with gentle torque; never force a prolapsed loop.
2. Confirm wire in true lumen—not subintimal—before predilation or stenting; contrast injection or dual-wire techniques may be used by the operator.
3. Maintain wire position during equipment exchanges; use wire holders, extension wires, and torque devices as requested.
4. Avoid deep seating of guide catheter that traps wire and restricts movement.
5. Monitor ST segments and chest pain during prolonged wiring attempts—ischemia may require pause or nitroglycerin per protocol.

RCIS anticipates second wire for bifurcation, microcatheter for support, and wire retrieval devices if fractured.

Lesion Preparation

Lesion prep modifies plaque so balloons and stents can cross, expand, and appose the wall. Under-prepared calcified lesions cause stent under-expansion—a major predictor of stent thrombosis and restenosis.

Predilation with Balloons

Semi-compliant balloons sized to reference vessel diameter crack plaque and verify crossing before stent. High-pressure predilation in resistant lesions may require non-compliant balloons after initial SC inflation.

Specialty Balloons

• Cutting balloons — micro-blades score plaque; useful in ostial and resistant fibrotic lesions.
• Scoring balloons — non-blade scoring elements (e.g., wrap wires) modify plaque without blade depth.

Use per physician preference and IFU; RCIS confirms artery size match and rated pressure.

Debulking and Atherectomy

When balloon alone fails:

Debulking increases embolization and slow-flow risk—have thrombus aspiration, GP IIb/IIIa, and temporary pacing readiness in RCA lesions when ordered.

Thrombus Management Before Stenting

In STEMI or thrombotic lesions, manual aspiration thrombectomy, rheolytic systems (where still used), or stent retrievers may reduce thrombus burden before stenting. Communicate TIMI thrombus grade before and after aspiration (see below).

TIMI Flow Grades (0–3)

The Thrombolysis In Myocardial Infarction (TIMI) flow grade describes antegrade coronary perfusion distal to the lesion—most critical for the infarct-related artery (IRA) in acute MI, but used in elective PCI when flow is compromised.

Primary PCI goal in STEMI is restoration of TIMI 3 flow in the IRA. TIMI 2 may still leave jeopardized myocardium; operators often pursue additional aspiration, balloon, or stent optimization.

RCIS role: call out flow changes during cine review, ensure ECG and hemodynamic monitoring when flow is restored (reperfusion arrhythmias), and document final TIMI flow in the procedural record.

TIMI Frame Count (Context)

Some items reference corrected TIMI frame count (CTFC)—a quantitative measure of contrast transit. Lower counts imply faster flow. RCIS may be asked to note frame counts on research cases; know it supplements grade 2 versus 3 distinction.

TIMI Thrombus Grades (0–5)

TIMI thrombus grade quantifies angiographic thrombus burden in the IRA—important in STEMI when deciding aspiration strategy and predicting no-reflow.

Higher thrombus grades correlate with slower flow restoration and distal embolization risk. After aspiration or stenting, re-grade thrombus and flow for documentation.

Integrating Wiring, Prep, and Grades in Case Flow

A structured mental model for RCIS:

1. Assess angiogram — estimate thrombus grade and baseline TIMI flow.
2. Stage wires and prep devices per lesion complexity (calcium on fluoroscopy → atherectomy tray).
3. Cross lesion — monitor ischemia; communicate if wire appears subintimal.
4. Prep lesion — predilation or debulk; watch for slow flow or dissection.
5. Re-assess flow and thrombus — target TIMI 3 with minimal thrombus before final stent optimization.
6. Deploy stent (Section 10.1) and confirm TIMI 3 with no reflow.

During slow flow/no-reflow, support includes intracoronary nitroglycerin, adenosine, verapamil, nicardipine per lab protocol, inotrope/vasopressor readiness, and temporary pacing for bradyarrhythmias.

Safety and Radiation During Wiring

Prolonged wiring increases fluoroscopy time—enforce ALARA, collimation, and dose awareness. RCIS may operate capture pedals, manage contrast syringes, and limit staff exposure via shield positioning.

Documentation

Record wire type, prep devices used (balloon sizes/atm, burr size/rpm if applicable), initial and final TIMI flow, and thrombus grade when STEMI. These fields appear in CathPCI and hospital quality metrics.

Study Tips for RCIS Items

• Distinguish TIMI flow (perfusion) from TIMI thrombus (clot burden)—they answer different questions.
• TIMI 1 is not "almost TIMI 3"—it is penetration without distal bed perfusion.
• Lesion prep is not optional in heavy calcification—exam scenarios often hide under-expanded stents after skipped prep.

Wiring and prep are where PCI succeeds or fails before a stent is ever opened. Mastering wire support concepts, prep tools, and TIMI scales lets you anticipate the next device and speak the same language as the interventional cardiologist under time pressure.