Conventional Mapping Haitham Badran Ain Shams University it Introduction The mapping approach used to guide ablation depends on the type of arrhythmia being assessed. Simple fluoroscopic anatomy is essential for conventional contact mapping and ablation
SVC RA IVC RV Anterior TV MV CS Posterior
Conventional Contact Catheter Mapping Electrogram recording methods Activationsequence mapping Pace Mapping Entrainment mapping Miscellaneous mapping maneuvers
Electrogram recording methods Unipolar and Bipolar Electrograms Methods Poten als generated by current sources in the heart are always recorded with respect to a potential at a fixed reference site. Sites at which han activation wave arises reveal themselves by an initially negative deflection in the unipolar recording. Application (WPW)
Application (Focal PVC) Advantages and disadvantages Unfiltered unipolar recording exact localization of target sites for ablation and a characteristic morphology at specific sites( QS deflection). Low amplitude local signals may be buried in remote far field components in the unipolar mode. Bipolar recording favourable in such situations.
Activation sequence mapping Methods Compares the ming of electrograms recorded from the roving catheter during tachycardia with the timing of a reference signal in order to either identify the earliest possible signal or a progression of activation around a macro reentrant reentrant circuit. Applications
Suitable ablation site Local electrogram precedes reference point (surface P or QRS ), and any other evidence of activity. (endocardial) Sharp Negative deflection in unipolar recording. Any movements result in latter electrogram. Advantages and disadvantages Ideal for focal incessant arrhythmias arising in structurally normal hearts such as FAT or RVOT tachycardia. For arrhythmias that are due to reentry early meets late configuration= Tachycardia CL. Catheter induced ectopy can satisfy sats ythe eabato ablation criteria in non sustained arrhythmias. SCAR related reentry abnormal low amplitude and fractionated, with multiple rapid peaks.
Pace Mapping Cardiac activation sequence generated by a particular arrhythmia can be reproduced by pacing at its origin at a similar cycle length.
Advantages and disadvantages Helpful in identifying the source of a focal tachycardia During sinus rhythm. More accurate in V rather than AT. The area with ihexcellent pace map criteria i may be relatively large. Entrainment mapping Entrainment is the continuous resetting of a reentry circuit. Reentry circuits that can be entrained have an excitable gap at each point in thecircuit circuit, defined by the time between recovery from the last depolarization and the arrival of the next excitation wavefront.
Requirements for entrainmentmappingmapping The arrhythmia h is due to reentry and can be entrained (Waldo criteria) Constant fusion during pacing (assessed from electrograms or ECG) Progressive fusion as the pacing rate is increased Block of the orthodromic wavefront terminates t tachycardia and changes activation sequence
Stable activation sequence (monomorphic) of tachycardia Stable tachycardia cycle length Pacing captures Pacing does not change or terminate the arrhythmia (either activation sequence or cycle length)
Post pacing interval Indication of the proximity of the pacing site to the reentry circuit Measured dfrom the last stimulus that entrains or resets the tachycardia to the next activation at the pacing site TCL PPI Concealed fusion
At pacing sites in the reentry circuit the PPI approximates the tachycardia cycle length. A PPI tachycardia cycle length difference of 30 msor less often indicates sufficient proximity for successful ablation of reentrant VTs, 20 ms in atrial flutter circuits. Limitations of PPI Does not indicate whether the pacing site is in a narrow isthmus in the circuit in comparison with a broad loop, in which ablation may be difficult. If conduction slows in the reentry circuit during pacing (AAD, Post ablation, Rapid pacing 20 30 msec > TCL), the PPI will falsely increase.
Entrainment with concealed fusion Usually indicates that the pacing site is in a reentry circuit isthmus It is occasionally observed at bystander sites adjacent to the reentrycircuit These are identified by a PPI that exceeds the tachycardia cycle length Subtle changes in QRS morphology, indicating that the site is an outer loop rather than a reentry circuit isthmus, 12leads should be used.
Concealed fusion with PPI=TCL TCL PPI Concealed fusion
Usesof entrainmentmapping mapping Limitations ofentrainment mapping Requires a stable reentry circuit. It is not useful, and complicates mapping attempts, if pacing repeatedly changes the tachycardia from one circuit to another or terminates tachycardia. is difficult to apply to tachycardias that are unstable due to hemodynamic collapse.
Applications Ventricular tachycardia identifying isthmuses for ablation, LT or RT. AVNRT & AVRT with paraseptal pathways PPI from RV apex > 100msec in AVNRT. AT (Macrorentrant) t) LT or RT Practical approach
Miscellaneous mapping maneuvers Fractionated Local electrogram and Voltage mapping. Response to Atrial and Ventricular pacing. Diastolic potentials at Exit Point NSR VT
Diastolic potentials Which Technique for Which Tachycardia? Focal tachycardia A Incessant Ac va on Map B Intermi ent Pace Map Reentrant tachycardia A Entrainment
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