Cardiac Catheter Ablation

Aka: Cardiac Catheter Ablation, Cardiac Ablation, Atrial Fibrillation Ablation, Supraventricular Tachycardia Ablation, Atrial Tachycardia Ablation, Atrioventricular Nodal Reentrant Tachycardia Ablation, AVNRT Ablation, Atrial Flutter Ablation, Atrioventricular Reciprocating Tachycardia Ablation, AVRT Ablation, Atrial 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. Ablation is preferred for WPW and Atrial Fibrillation
      4. Success rate: 60-80%
      5. 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
         1. Due to myocardial perforation by guidewire, dilator or thermal energy
         2. Occurs in up to 0.2 to 5% of patients
         3. Typically occurs during procedure or prior to hospital discharge
            1. However, presentation may be delayed as long as 2 weeks after procedure
         4. Obtain Bedside Ultrasound
            1. Maintain high index of suspicion in cardiopulmonary symptoms (e.g. Dyspnea) after ablation
      3. Atrial Perforation (esp. with Atrioesophageal fistula)
         1. Rare (<0.25% of cases)
         2. Complications
            1. Atrioesophageal fistula
            2. Esophageal Perforation
         3. Presentations at 1 to 6 weeks after ablation (mean 2 weeks)
            1. Fever
            2. Chest Pain
            3. Dyspnea
            4. Nausea or Vomiting
            5. Odynophagia
            6. Hematemesis or melana
            7. Air emboli resulting in neurologic deficits
         4. Evaluation
            1. CT Chest with contrast
            2. Avoid endoscopy (risk of air emboli)
      4. Complete atrioventricular nodal block (complete Heart Block)
         1. Requires emergent Pacemaker placement
      5. Pneumothorax
         1. Rare complication (typical access is via femoral vein)
      6. Femoral Vein access complications
         1. Vessel perforation (e.g. retroperitoneal Hematoma)
         2. Symptomatic Anemia
      7. Myocardial Infarction
         1. Rare with ablation and Troponin Is not typically recommended unless ischemic EKG
         2. Single Troponin Is more likely to be falsely positive due to the ablation thermal injury
      8. Esophagitis
         1. Occurs in up to 20% of cases
         2. Esophagus lies behind left atrium and is susceptible to thermal injury
   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. Recurrent Atrial Fibrillation (repeat procedure required in up to 20% of cases)
      3. 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. Typical Catheter Ablation Procedure
      1. Ablation probe applied in same pattern as MAZE procedure
      2. Ablation circumferentially around each set of pulmonary veins
         1. Also ablate a line between the two pulmonary veins within the left atrium
      3. Ablation circumferentially around superior and inferior vena cava entry within the right atrium
   2. Other procedures: AV Nodal ablation with Pacemaker placement indications
      1. Older patients with Tachycardia induced Cardiomyopathy
      2. Refractory rapid ventricular rate despite maximal medical therapy
   3. Anticoagulation
      1. Anticoagulation for one month before and several months after ablation
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 [PubMed]
7. References
   1. Demeester and Swaminathan in Swadron (2022) EM:Rap 22(1): 15-6
   2. Gutierrez (2017) Am Fam Physician 83(1): 61-8 [PubMed]
   3. Scheinman (2003) Pacing Clin Electrophysiol 26(3): 789-99 [PubMed]
   4. Shapira (2009) Am Fam Physician 80(10): 1089-94 [PubMed]