Balloon cryoablation simplifies atrial fibrillation ablation.
Atrial fibrillation starts by pulmonary veins firing extra ( premature ) beats , which initiates fibrillatory activity in the atrium. Ablation procedures are directed to isolate electrically pulmonary veins ( PV ) from the rest of the atrium.
This can be accomplished with point-by point lesions, created with RF applications ( thermal energy ) or with cryoablation ( freezing ). Balloon cryoablation creates circular lesions, which are more contiguous . Most recent randomized clinical trials demonstrated superior results of cryoablation ( comparing with RF ) in regards to rate of recurrent arrhythmias as well decreased complication rates. Cryoablation mechanisms are very different from RF energy ( see pages 4-5 for more details in regards to lesion morphology and tissue effects. ). Below is a snapshot from ablation procedure, demonstrating isolation of pulmonary veins after cryoballoon ablation with 3-D voltage map of the left atrium. Grey color represents low voltage , ablated areas ( less than 0.2 mV ) and intact atrial tissue ( high voltage ) is in magenta.
This can be accomplished with point-by point lesions, created with RF applications ( thermal energy ) or with cryoablation ( freezing ). Balloon cryoablation creates circular lesions, which are more contiguous . Most recent randomized clinical trials demonstrated superior results of cryoablation ( comparing with RF ) in regards to rate of recurrent arrhythmias as well decreased complication rates. Cryoablation mechanisms are very different from RF energy ( see pages 4-5 for more details in regards to lesion morphology and tissue effects. ). Below is a snapshot from ablation procedure, demonstrating isolation of pulmonary veins after cryoballoon ablation with 3-D voltage map of the left atrium. Grey color represents low voltage , ablated areas ( less than 0.2 mV ) and intact atrial tissue ( high voltage ) is in magenta.
Cryoablation procedure
Isolation of pulmonary veins translates to approximately 70-75% cure rates for patients with paroxysmal atrial fibrillation with single ablation procedure. Some patients, however may have additional triggers , initiating atrial fibrillation and localized outside of the pulmonary veins., resulting in incomplete resolution of atrial fibrillation and symptoms after PV isolation.
Presence of lung disease, structural heart disease, valve abnormalities, large atrial size, large scar areas , sleep apnoe , obesity and some other factors decreases success rates of ablation.
In majority of patients undergoing AF ablation--normal rhythm can be maintained after PV isolation with continuing previously ineffective medications. In some patients atrial fibrillation episodes may persists, although usually episodes are significantly reduced in regards to duration and frequency and usually easier controlled with medications , than prior to procedure. Some patients may require additional ablation, if still has significant episodes, beyond 3 months after initial ablation procedure.
It is more difficult ,however to treat persistent atrial fibrillation ( more than 3 months duration ) due to adverse remodeling and scar formation in the atrium as result of pronged fibrillation. In chronic atrial fibrillation--left atrium enlarges and forms significant areas of scar tissue. These patients requires ablation of additional areas and there is significant controversy in regards to additional targets and strategies for ablation . Cure rates are significantly reduced or patient may not respond to ablation procedure ( to late ). For patient with chronic atrial fibrillation-the other option is hybrid ablation. Hybrid ablation is performed by a team of cardiac surgeon and electrophysiologist. Essentially-in addition to PVI, large areas of atrium are electrically excluded from the rest of the atrium.
Presence of lung disease, structural heart disease, valve abnormalities, large atrial size, large scar areas , sleep apnoe , obesity and some other factors decreases success rates of ablation.
In majority of patients undergoing AF ablation--normal rhythm can be maintained after PV isolation with continuing previously ineffective medications. In some patients atrial fibrillation episodes may persists, although usually episodes are significantly reduced in regards to duration and frequency and usually easier controlled with medications , than prior to procedure. Some patients may require additional ablation, if still has significant episodes, beyond 3 months after initial ablation procedure.
It is more difficult ,however to treat persistent atrial fibrillation ( more than 3 months duration ) due to adverse remodeling and scar formation in the atrium as result of pronged fibrillation. In chronic atrial fibrillation--left atrium enlarges and forms significant areas of scar tissue. These patients requires ablation of additional areas and there is significant controversy in regards to additional targets and strategies for ablation . Cure rates are significantly reduced or patient may not respond to ablation procedure ( to late ). For patient with chronic atrial fibrillation-the other option is hybrid ablation. Hybrid ablation is performed by a team of cardiac surgeon and electrophysiologist. Essentially-in addition to PVI, large areas of atrium are electrically excluded from the rest of the atrium.
