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1、Rescue Ablation of Electrical Storms in a Patient with Remote Myocardial Infarction,Katherine Fan Grantham Hospital Hong Kong SAR,Patient Mr. L,M/64 History of inferior MI 1989- MVR for papillary muscle rupture and severe MR Ischemic cardiomyopathy (EF 30%) VT 1997- ICD implanted / generator change
2、2002 Chronic smoker/ COPD,Ventricular Arrhythmias,ICD (single-chamber) 1997 Amiodarone added in 2001 for PAF/ NSVT Recurrent VT episodes in 3/2005 with increased dosage of amiodarone Developed SOB- diagnosed amiodarone induced pulmonary fibrosis: Amiodarone stopped/ High dose steroids required -bloc
3、kers / sotalol- not tolerated exacerbation of COPD Recurrent VT episodes- mexiletine started but complicated by neurological signs (limb tremor and gait instability),Electical Storms,Nov 2005- admitted after recurrent ICD shocks Interrogations: 58 episodes of VT detected Most terminated with ATP Som
4、e accerlerated to fast VT which was then termianted with cardioversion shocks Early re-initiation of VT,VT Morphologies,LBBB/ Left superior axis QRS,RBBB/ Right superior axis QRS,ATP,RBBB/R sup,LBBB/ L sup,RBBB/ R sup,Mitral valve prothesis,RAO,INF,Sinus Rhythm,VT 1,VT 2,Lesions Created,Termination
5、of VT (RF #38!),on,RF,Catheter Ablation of the Mitral Isthmus for VT associated with Inferior Infarction Wilber et al. Circulation 1995;92:3481-3489,By virtue of its narrow dimension, the isthmus became the vulnerable point to interrupt this circumferential activation,RBBB/ Right superior axis,LBBB/
6、Left superior axis,Mitral Isthmus Ventricular Tachycarida,Critical zone of slow conduction activated parallel to mitral isthmus in either direction resulting in 2 distinct but characteristic QRS configurations LBBB with left superior axis- rS in V1 and aVR/ R in V6, I, aVL RBBB with right superior a
7、xis- R in V1 and aVR/ QS in V6, I, aVL,LBBB/LAD,RBBB/RAD,Wilber et al. Circulation 1995,Dynamic Substrate Map Sinus Rhythm,Low Voltage Zone,RAO view,Inferior view,Dynamic Substrate Map Ventricular Tachycardia,RAO view,Inferior view,Low Voltage Zone,Composite Substrate Profile,DSM Sinus Rhythm,Compos
8、ite Substrate Map,DSM VT,Fixed Block,Functional Block,Marked Lesions,RAO view,Inferior view,Another Marked Lesions,RAO view,Inferior view,Substrate-Orientated VT Ablation,A definite trigger or delineated scar has been characterized as a requirement for substrate orientated ablation of intractable un
9、mappable VT Targets Critical isthmus Areas of slow conduction Exit sites- often located at the border of the scarred myocardium,Scar Border Zone Substrate,VT originated from area of diseased tissue surrounding dense scar Based on surgical approaches to treat VT (sub-endoardial resection), methods of
10、 ablating ischemic VT by “ substrate mapping” in SR have been used successfully in pts with drug refractory hemodynamically unstable MMVT Use electroanatomical voltage mapping to define regions of scar and viable endocardium in SR followed by ablations in the border zone regions,Anatomical vs Functi
11、onal Substrate Limitation of Voltage Mapping during SR,Boundaries of the isthmus could be functional lines of block not detected during SR Dispersion of voltage (heterogeneity) in scar areas may appear only when activated at VT rate and/or orientation Post MI structural remodeling Alteration of anis
12、otropy depended on electrotonic loads and orientation,Summary,Successful ablation of mitral isthmus for VT associated with remote inferior infarction Characteristic of VT morphologies and its corresponding activation mappings demonstrated Dynamic substrate mapping during SR and VT provided complimen
13、tary data on substrate identification (anatomical vs functional),Ventricular Tachycardia 1,Ventricular Tachycardia 2,Relationship Between Successful Ablation Sites and the Scar Border Zone Defined by Substrate Mapping for Ventricular Tachycardia Post-MI Verma et al. JCE 2005:16:465-471,29,59,8,15,7,
14、9,2,3,* Dense scar= bipolar voltage 0.5mV,Successful Ablation Within Scar,Critical isthmus may originate in scar and exit in border zone or may exist entirely within scar Thin strands of surviving myocytes “zigzagging” through dense areas of scar- substrate Thick layers of survivung myocardium exist
15、ing beneath dense endocardial scar- ?return path of circuit Linear ablations that extend outside of the scar border and into the regions of dense infarction may be required Some advocated targeting sites within scar by identification of isolated, delayed components of local EGM,Anatomical Substrate
16、vs Electrophysiological Substrate,Anisotropy- determined by cell orientation/ morphology and cell-to-cell connections (gap junctions) Diseased state (eg MI/ heart failure)- structural remodeling alters the ansiotropy and increases its heterogeneity and potential for arrhythmia development ? Extent o
17、f “ functional substrate” depends on the electrotonic loads and orientation,Entrainment mapping Limitations Mainly based on activation times that are valid only when the reentry pathway through the circuit is not changed during entrainment Tissues that were able to sustain a VT may be different from that which is responsible for initiation of VT,
