Access
  • Right common femoral artery (alternatively, radial): 6Fr sheath
  • Left common femoral artery (alternatively, radial): 5Fr sheath
  • Right internal jugular vein: Tempo Lead temporary pacemaker (if patient does not already have a permanent pacemaker).
Equipment
  • 6Fr sheath and 6Fr left coronary guide catheter of choice
  • 5Fr sheath and 5Fr multipurpose (MP) catheter.
  • Temporary pacemaker (with sheath and locking cover)
  • 014” guidewire (Fielder or Whisper)
  • 100% absolute alcohol
  • Compliant over the wire (OTW) balloon (1.5×9 or 2.0x9mm)
  • Intraprocedural Transthoracic echocardiography (TTE)
  • DefinityÒ contrast injection
Hemodynamic Assessment
  • Simultaneous pressure measurement of LV outflow region and ascending aorta (assess for gradient via pullback with MP catheter from LV apex to LV outflow tract).
  • Assess for Brockenborough-Braunwald-Morrow sign (Figure) – Drop in post-extrasystolic aortic pulse pressure.

Technique
  • Place temporary pacemaker (if no PPM) via right internal jugular vein. The temporary pacemaker should be left in place for at least 48 h post ablation.
  • Draw baseline CPK, CK-MB, and troponin levels.
  • Perform coronary angiography to determine most appropriate septal artery for ablation to evaluate for CAD (Figure).
    • Both left and right coronary arteries should be assessed as the proximal RCA can give rise to basal septal arteries.
    • RAO (Straight and caudal) projection: Angulation of origin of septal artery; Cranial projection: Length of septal and course of septal artery.
  • Use MP catheter in LV via second arterial access to measure resting and post-PVC LV gradient.

  • Administer Angiomax with goal ACT > 300s
  • After engaging the guide catheter, wire the first major septal branch and negotiate OTW balloon to most basal septal branch.
  • Inflate OTW balloon (size according to septal artery diameter) to 5-6 atm and perform cineangiography of LAD to confirm no compromise of LAD flow and balloon position (Figure).

  • Inject DEFINITY contrast (Dilute 0.8 mL of DefinityÒ into 10 cc saline, then draw up 1 cc into a small syringe and inject 1 cc at a time) while the balloon is inflated. The goal is to avoid enhancement of RV, free walls, or papillary muscles and to delineate the septum (Figure). Withdraw the guidewire out of the OTW balloon under water seal.

  • Inject absolute alcohol (100% absolute, 1-3 mL) through the lumen of inflated balloon (no more than 1 mL/min with a timer). Slow the injections if the patient develops heart block, premature ventricular contractions, or intraventricular conduction delay (IVCD). Usually, the gradient starts to decline with successful alcohol injection.
  • Note: If patient develops transient heart block or IVCD, HOLD injection for 3-5 min (balloon remains inflated) and restart if rhythm reverts to normal. STOP injection if patient has developed persistent heart block or IVCD (even if 1, 2 or 3 cc of alcohol has been injected).
  • Continue total balloon inflation time of at least 5 min (after stopping alcohol injection).
  • Continue TTE monitoring and measure the LVOT gradient while the balloon is inflated and remove any residual alcohol from lumen by additional saline flush.
  • If resting gradient < 20 mmHg, deflate balloon and finish after confirming LAD patency (Figure).
  • If resting gradient > 20 mmHg, consider injecting another septal artery or the same septal artery more proximally.
  • The average number of arteries injected = 1.7; average volume of alcohol injected = 3mL.

  • Acute procedural success (80-85%) is defined as ³50% reduction in peak resting or provoked LVOT gradient with a final residual resting gradient of < 20 mmHg (Figure).

 

  • Further reduction in LVOT gradient occurs over 3-6 months due to ventricular remodeling and basal septal thinning.
Complications
  • Chest pain during the procedure (this can be usually treated with IV narcotics)
  • Most common complication: 10-20% of patients develop new conduction abnormalities (RBBB, LAFB, LBBB). 8-10% may develop complete heart block requiring PPM; this rate approaches 30% if baseline LBBB or RBBB is present.
  • Ventricular fibrillation/tachycardia
  • Overall periprocedural mortality of 2%.
Post-procedure
  • Observe in ICU setting for at least 2 days. The temporary pacemaker is left in the patient for 48 h post-procedure.
  • Post procedural elevation of CPK (between 800-1200 U/L) usually occurs. The amount of elevation depends upon amount of alcohol injected, vessel size, and method of enzyme measurement.
  • Patient can be discharged home once CK-MB level falls below <10x normal (<60 units).
  • Aspirin 81 mg po once daily should be continued indefinitely.
  • If a patient is on beta- and/or calcium-channel blockers, medical therapy can be reduced by discontinuation of one class if patient is on both, or reduction in dosage if the patient is only on one class of medication.
  • Repeat TTE the next day.
  • Follow-up TTE should be performed at 6 months and annually thereafter. There will be additional 30% reduction in septal thickness over next 4-6 weeks on follow-up TTE.