Why we use it
Heparin is our first-line intra-procedural anticoagulant in the EP lab. Anywhere a catheter sits in the left atrium — or crosses the septum to get there — clot risk is real, and unfractionated heparin gives us a titratable, reversible answer. It binds antithrombin and accelerates inactivation of thrombin and factor Xa. Onset is essentially immediate when given IV, which is exactly what we need around transseptal puncture.
Indication in the lab
- All left-atrial procedures (AF ablation, atypical flutter, LA tachycardias)
- Any transseptal puncture, including WATCHMAN and mitral structural cases
- Left-ventricular mapping/ablation (PVC, VT)
- PFO/ASD work
- Generally not needed for right-sided-only cases (SVT, typical flutter, EP study)
Dose and route
- Initial bolus: 100 U/kg IV, ideally given before the needle crosses the septum.
- Some attendings prefer pre-bolus of 50–75 U/kg before the puncture and the rest immediately after — confirm preference on the timeout.
- Redose: 1,000–5,000 U boluses to keep ACT in goal range. Long cases often need a continuous infusion (e.g., 1,000 U/hr) once steady-state is achieved.
- All boluses given through a central or large peripheral line, never through the transseptal sheath until flushed.
Monitoring
- First ACT drawn 5 minutes after the bolus.
- Repeat every 20–30 minutes during the case, and any time the operator asks (especially after long pauses in catheter movement).
- Target ACT 300–350 s for LA work. RF and cryo PV isolation both use this range.
- If ACT drifts under 300, redose. If it climbs above 400, hold and recheck in 15 minutes.
- Document every bolus, every ACT, and the time on the case record.
Onset and duration
- Onset: seconds to minutes IV.
- Half-life: roughly 60–90 minutes, but dose-dependent — bigger boluses last longer.
- Effect tapers naturally if no protamine is given; many short cases simply pull sheaths once ACT falls below ~180.
Side effects and what to watch for
- Bleeding at access sites — groin hematomas are the most common headache. Manual pressure protocols and figure-of-eight sutures help.
- Pericardial effusion / tamponade is amplified by full heparinization. Sudden hypotension during or after transseptal work — call it out immediately.
- Heparin-induced thrombocytopenia (HIT): consider in any patient with prior heparin exposure and a platelet drop. Flag preop history of HIT — bivalirudin is the alternative.
- Allergic reactions are rare but possible, especially with bovine-source products (most labs use porcine).
Reversal
- Protamine sulfate reverses heparin. Rough rule: 1 mg protamine per 100 U of heparin given in the last 2–3 hours, capped around 50 mg per slow push.
- Push slowly (over 10 minutes) — fast administration causes hypotension and, rarely, anaphylactoid reactions.
- We don’t reverse routinely after AF ablation; we typically let the heparin wear off and pull sheaths at an ACT cutoff. Reversal is reserved for bleeding, tamponade, or early sheath pull on operator request.
Common pitfalls
- Bolusing through the transseptal sheath before it’s flushed — air or clot risk.
- Forgetting to redose during long mapping pauses; the catheter sits still and clot forms on it.
- Trusting one ACT and not rechecking — the curve is not linear in every patient.