Abstract
Background
Achieving bidirectional block (BB) is generally considered to be the endpoint in the ablation of typical atrial flutter (AFL), however acute reconnection is common. Recent data suggest that deeper ablation lesions may be created by decreasing the irrigant ionic concentration using half normal saline (HNS) delivered through an open irrigated ablation catheter compared with normal saline (NS). We sought to assess whether the use of HNS was associated with a more rapid achievement of BB and less reconnections compared with NS.
Methods
Patients were randomly allocated to catheter ablation with either NS or HNS using a 4-mm irrigated catheter at a power setting of 30 W. Ablation approach employing either a maximum voltage guided (MVG) or empiric cavo-tricuspid isthmus (CTI) line was performed aiming for BB that was confirmed by double potentials separated by an isoelectric line measuring ≥110 ms and evidence of conduction block using differential pacing. Study was powered to an endpoint of acute reconnection within 30 mins.
Results
A total of 60 patients underwent catheter ablation for typical AFL with either HNS (n=30) or NS (n=30). There were no significant differences between the two groups in terms of patient age (68±7 yrs HNS vs. 68±10 yrs NS) and BMI (31±7 HNS vs 31±5 NS). BB was achieved in all patients. The MVG approach was employed in 28/60 patients. Acute reconnection was observed in 11 patients (18%); 4 in HNS vs 7 in NS group (ns). The mean RF time to achieve BB was 386±262 seconds in HNS vs 456±270 seconds in NS (p=0.21). The approach to CTI ablation showed a significant difference in time to BB: Time to block in MVG cases was 264±143 seconds vs 567±273 in empiric CTI line cases. Figure 1 demonstrates the time to block in both approaches with the choice of irrigant not appearing to impact the time to BB. There were 4 steam pops in the HNS arm and 0 steam pops observed in the NS arm. There were no significant complications in either arm.
Conclusion
Irrigation with HNS resulted in no statistically significant reduction in duration of RF time or improvement in acute outcomes over NS in the atrial flutter population. Reduction in duration of RF time was driven by MVG approach. However, acute reconnections were higher in NS group, all 4 steam pops occurred in HNS arm.
Figure 1
Funding Acknowledgement
Type of funding source: None
Diastolic isthmus length and 'vertical' isthmus angulation identify patients with difficult catheter ablation of typical atrial flutter: a pre-procedural MRI study
