Definition of Terms
Types of Atrial Fibrillation

  • Paroxysmal – Episodes occurring intermittently and tending to terminate spontaneously - usually within 48 hours.
  • Persistent – Episodes lasting longer than 7 days and not terminating spontaneously, but can be terminated with chemical or electrical cardioversion.
  • Permanent – Constant (chronic, 24/7) afib not amenable to effective termination by cardioversion.
  • Adrenergic – Episodes occurring almost exclusively during daytime, often in connection with exercise or emotional or work-related stress.
  • Vagal – Episodes tending to occur during rest, at night or after a meal. Alcohol and cold drinks are common triggers.
  • Mixed (random) – Episodes occur anytime and do not consistently fit the adrenergic or vagal pattern. Catheter Ablation and Maze Procedures
  • Focal ablation – The original radiofrequency (RF) ablation procedure in which specific active foci of aberrant impulses are located and ablated.
  • Pulmonary vein ablation (PVA) – An ablation procedure in which a ring of scar tissue is placed just inside the pulmonary veins where they enter the left atrium. The original PVA carries a high risk of pulmonary vein stenosis, so it is rarely used in this form anymore. Thus, the term PVA is now associated with ablation around the pulmonary veins when a more specific description (SPVI, CAPVI or PVAI) is not provided by the EP or the exact type of PVA is not known by the respondent.
  • Pulmonary vein isolation (PVI) – An ablation procedure, also known as ostial ablation, in which a ring of lesions is placed on the left atrium wall such as to encircle each pulmonary vein. This procedure reduces the risk of stenosis since the scar tissue is created in the atrium wall rather than inside the pulmonary veins themselves
  • Segmental pulmonary vein isolation (SPVI or Haissaguerre procedure) – In this procedure electrophysiological mapping (using a multipolar Lasso catheter) is used to locate the pathways taken by aberrant impulses from the pulmonary veins and these pathways are then eliminated by ablation around the veins approximately 5 to 10 mm from the ostium of the veins.
  • Pulmonary vein antrum isolation (PVAI or Natale procedure) – This procedure is a variant of the SPVI procedure. It involves locating aberrant pathways through electrophysiological mapping (using a multipolar Lasso catheter) and ablating these pathways guided by an ultrasound (ICE) catheter. The ablation is performed as close as possible to the outside edge (antrum) of the junction between the pulmonary veins and the atrial wall. All four pulmonary veins as well as the superior vena cava (if indicated) are isolated during the procedure.
  • Circumferential anatomical pulmonary vein isolation (CAPVI or Pappone procedure) – In this procedure anatomical mapping (CARTO) is used to establish the exact location of the pulmonary veins. Two rings of lesions are then created in the left atrium - one completely encircling the left pulmonary veins and another completely encircling the right pulmonary veins; the two rings are usually joined by a linear lesion.
  • All three variants of the PVI procedure may be followed by focal ablation involving other areas of the atrium wall or creation of linear lesions in order to eliminate sources of afib located outside the pulmonary veins.
  • Right atrial flutter ablation – This procedure involves the application o radiofrequency energy to create a block of the cavotricuspid isthmus in the right atrium so as to interrupt the flutter circuit. A right atrial flutter ablation is usually successful in eliminating the flutter, but rarely helps eliminate atrial fibrillation and may even, in some cases, initiate the development of atrial fibrillation.
  • Left atrial flutter ablation – Left atrial flutter is a common complication of ablation for atrial fibrillation. It most often resolves on its own, but if not it may be necessary to re-enter the left atrium, locate the offending circuit, and block it via radiofrequency catheter ablation.
  • Cryoablation – In this procedure a nitrogen-cooled or argon-cooled, rather than electrically-heated, catheter is used to create the ablation lesions.
  • Maze procedure – The original surgical procedure, the full maze or Cox procedure, used a cut-and-sew protocol for creating lesions forming a "maze" that conducts the electrical impulse from the SA to the AV node, while at the same time interrupting any "rogue" circuits. The cut-and-sew method has now largely been replaced by the use of RF-powered devices, but cryosurgery, microwave application, and high-intensity focused ultrasound (HIFU) have all been tried as well and are preferred by some surgeons. Creating the full set of maze lesions usually requires open- heart surgery and the use of a heart/lung machine.
  • Mini-maze procedure – The so-called mini-maze procedure also involves lesions on the outside of the heart wall, but access to the heart is through incisions between the ribs rather than via open-heart surgery. The mini- maze may involve the creation of the full maze set of lesions, but usually focuses on pulmonary vein isolation. The procedure does not involve the use of a heart/lung machine and lesions are usually created by the application of RF energy or cryoenergy.
  • AV node ablation – This ablation approach aims at eliminating the effects of fibrillation in the atria on ventricular performance by isolating the AV node [the ventricular beat controller] from any extraneous impulses and feed it its "marching orders" from an implanted pacemaker. Statistical Terms
  • N – The number of respondents in a sample.
  • Mean – The average value for a group of data, i.e. the sum of the values
  • of all data points divided by the number of data points.
  • Median – The value in the middle of a group of data, i.e. the value above which half of all individual values can be found and below which the remaining 50% can be found.
  • Statistical significance – In this study average values are considered different if the probability of the difference arising by chance is less than 5 in 100 using the two-tailed t-test. This is expressed as "p" [probability] being equal to 0.5 or less. Lower values of p are indicative of a greater certainty that observed differences are truly significant.. Definition of Success
  • Complete success – No afib episodes, no antiarrhythmics, consistent sinus rhythm (success score=10)
  • Partial success – No afib episodes, but on antiarrhythmics to maintain consistent sinus rhythm (success score=5)
  • Failure – Afib episodes still occurring with or without the use of antiarrhythmics (success score=0)
  • Blanking period – The first 6 months following the final procedure
  • Index period – The last 6 months of the 12-month period following the final procedure for the purpose of curing afib
  • Initially successful – No afib episodes and no antiarrhythmics during the index period.
  • Uncertain – Cases where insufficient data is available or where less than 3 months has gone by since the procedure and afib episodes are still occurring.