Cardiac Catheter Ablation

1. Indications
   1. Atrial Tachycardia
      1. Ablation indicated in symptomatic Atrial Tachycardia refractory to medical therapy (e.g. Beta Blocker)
      2. Also indicated in Tachycardia-mediated Cardiomyopathy
   2. Atrioventricular Nodal Reentrant Tachycardia (AVNRT)
      1. Ablation indicated in most AVNRT cases (Most common indication for catheter ablation)
   3. Atrioventricular Reciprocating Tachycardia (AVRT)
      1. Includes Wolff-Parkinson-White Syndrome (WPW)
      2. Ablation indicated in episodic Tachycardia and signs of accessory pathway conduction (delta wave)
   4. Atrial Flutter
      1. Ablation indicated in most cases of Atrial Flutter
   5. Atrial Fibrillation and very symptomatic (esp. in young patients)
      1. Ablation indicated in normal left atrial size and symptomatic and refractory Atrial Fibrillation
2. Contraindications: Atrial Fibrillation Ablation
   1. Ejection fraction <35%
   2. Left atrial size >5.5 cm
   3. Mechanical Mitral Valve
   4. Age over 75 years old
3. Efficacy
   1. Atrial Tachycardia
      1. Success rate: 86 to 100%
      2. Complication rate: 8% or less
   2. Atrioventricular Nodal Reentrant Tachycardia (AVNRT)
      1. Success rate: 96%
      2. Complication rate: 1% or less
   3. Atrioventricular Reciprocating Tachycardia (AVRT)
      1. Success rate: 95%
      2. Complication rate: 2 to 4%
   4. Atrial Flutter
      1. Higher efficacy and lower complication rate than Atrial Fibrillation Ablation
      2. Success rate: 88-100%
      3. Complication rate: 2.5 to 3.5%
   5. Atrial Fibrillation
      1. Lower efficacy and higher complication rate than Atrial Flutter Ablation
      2. Best success is with normal left atrial size and paroxysmal Atrial Fibrillation
      3. Success rate: 60-80%
      4. Complication rate: 6-10%
4. Complications
   1. General risks (applies to all ablation procedures)
      1. Radiation exposure (fluoroscopy): 1.4 mSV to 50 mSv depending on length of procedure
         1. Electrophysiology study alone: 3.2 mSv
         2. Atrial Tachycardia Ablation: 4.4 mSv
         3. Atrioventricular nodal reentrant Tachycardia (AVNRT) ablation: 4.8 mSv
         4. Atrial Flutter Ablation: 12.1 mSv
         5. Atrioventricular Reciprocating Tachycardia (AVRT) ablation: 12.8 mSv
         6. Atrial Fibrillation Ablation: 16.6 mSv
      2. Cardiac perforation with tamponade
      3. Complete atrioventricular nodal block (complete Heart Block) requiring Pacemaker placement
   2. Atrial Flutter
      1. Ablation is at isthmus in right atrium and is a lower risk procedure
      2. Thromboembolic events
      3. Myocardial Infarction
   3. Atrial Fibrillation
      1. Ablation site is high risk due to proximity of major structures
      2. Complications (as high as 6% complication rate)
         1. Pulmonary vein stenosis
         2. Cerebrovascular Accident
         3. Cardiac perforation
         4. Atrial-esophageal fistula (rare)
         5. Thromboembolic events
5. Technique
   1. Ablation probe applied in same pattern as MAZE procedure
   2. Ablation circumferentially around each set of pulmonary veins and a line between the two within the left atrium
   3. Ablation circumferentially around superior and inferior vena cava entry within the right atrium
6. Protocol: Refractory and symptomatic Atrial Fibrillation despite maximal therapy
   1. AV Node Ablation with Pacemaker placement
      1. Last resort method that is rarely indicated
      2. Ozcan (2001) N Engl J Med 344:1043-51
7. References
   1. Scheinman (2003) Pacing Clin Electrophysiol 26(3): 789-99
   2. Shapira (2009) Am Fam Physician 80(10): 1089-94