Background
Mapping and ablation of fractionated electrograms is a common treatment for scar‐based ventricular tachycardia (VT). An automated algorithm has been developed for rapid “fractionation mapping.”
Methods
Electroanatomic maps from 21 ablation procedures (14 scar‐based VT and seven control idiopathic VT/premature ventricular contractions with normal voltage) were retrospectively analyzed using the Ensite Precision fractionation map (fMap; Abbott Laboratories; Abbott Park, IL, USA) algorithm. For each study, voltage maps and 30 fMaps were generated using combinations of parameters: width (5, 10, 20 ms), refractory time (15, 30 ms), sensitivity (0.1, 0.2 mV), and fractionation threshold (2, 3, 5). Parameter sensitivity was assessed by overlap of fractionated areas (fArea) with successful VT ablation sites (defined by entrainment and/or pace mapping). Specificity was assessed by presence of fractionated areas in control patients.
Results
Of the 30 fMap parameter sets tested, seven identified >50% of scar‐based VT ablation sites, and 26 contained <5 cm2 fractionation on control fMaps. Three combinations of fMap width/refractory/sensitivity/threshold parameters met both of the above criteria, and 20/30/0.1/2 identified the most VT ablation sites (79%) and generated 42.3 ± 28.2 cm2 of fArea on scar‐based VT maps compared with 4.9 ± 3.2 cm2 on control maps (P = .001). None of the control patients and 23% of the scar‐based VT patients had VT recurrence at mean 15 month follow‐up.
Conclusion
Careful selection of signal processing parameters optimizes sensitivity and specificity of automated fractionation mapping for scar‐based VT. Real‐time use of fMap algorithms may reduce VT ablation procedure time and improve substrate modification, which may improve outcomes.
FUSIC haemodynamics (HD) – the latest Focused Ultrasound in Intensive Care (FUSIC) module created by the Intensive Care Society (ICS) – describes a complete haemodynamic assessment with ultrasound based on ten key clinical questions: 1. Is stroke volume abnormal? 2. Is stroke volume responsive to fluid, vasopressors or inotropes? 3. Is the aorta abnormal? 4. Is the aortic valve, mitral valve or tricuspid valve severely abnormal? 5. Is there systolic anterior motion of the mitral valve? 6. Is there a regional wall motion abnormality? 7. Are there features of raised left atrial pressure? 8. Are there features of right ventricular impairment or raised pulmonary artery pressure? 9. Are there features of tamponade? 10. Is there venous congestion? FUSIC HD is the first system of its kind to interrogate major cardiac, arterial and venous structures to direct time-critical interventions in acutely unwell patients. This article explains the rationale for this accreditation, outlines the training pathway and summarises the ten clinical questions. Further details are included in an online supplementary appendix.
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