Surgical VT Ablation Techniques
With improvements in catheter-based ablation technology, the outcomes of percutaneous VT ablation have also been improved. However, inadequate contact force, epicardial fat tissue, substrate close to the coronary arteries and intramural foci limited the success with percutaneous ablation. The other important issue was pericardial adhesion. Soejima et al described a series of 6 patients with pericardial adhesion, for which a hybrid subxiphoid surgical window approach to treat VT in electrophysiology (EP) lab was adopted.(16) However, the subxiphoid approach allowed inadequate access to anterior and lateral regions. Michowitz then used limited anterior thoracotomy in patients with previous cardiac surgery and pericardial adhesion in EP lab.(17) This approach could permit access to the whole anterior and lateral wall as well as the apex. Anter et al reported their surgical cryoablation experience in 8 non-ischemic cardiomyopathy patients with refractory VT.(15) Two patients died of heart failure and sepsis eventually, while the other 6 patients had significant reduction in VT burden. All these studies emphasized that direct epicardial ablation via limited thoracotomy or even open chest approach could be effective in difficult VT cases.
Compared with percutaneous access, surgical RF ablation has the following advantages: (1) contact force is ensured by pressing the catheter tip against epicardium, which makes deeper lesions (Figure 1); (2) under direct vision, the substrates in close proximity to the coronary arteries could be ablated safely and adequately;(3) other concomitant surgical procedures could be done simultaneously; (4) in patients with CRT indication, the LV lead can be placed at a more electrophysiological site (high voltage, latest activation, away from scar) guided by 3-D electroanatomic mapping system. However, the limitation of this traumatic approach is apparent. This approach can only be served as the last resort for patients with frequent VT attack and refractory to both antiarrhythmic drugs and conventional ablation therapy, especially those with frequent ICD shocks.