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ELECTROPHYSIOLOGICAL STUDYMAPPING TECHNIQUES DR HIMAL RAJ.M SR CARDIOLOGY Contents History Electrophysiological mapping Mapping techniques Mapping sites History Josephson et al- endocardial catheter mapping of VT Huang et al,1985- radiofrequency catheter ablation Sternick EB, Gerken LM, Vrandecic MO. Appraisal of ‘Mahaim’ automatic tachycardia. J Cardiovasc Electrophysiol 2002;13:244–9. Electrophysiological mapping Mapping to localize site of origin of abnormal beats or to identify tachycardia circuit in case of reentrant arrhythmias Mapping procedures Pace Mapping Activation Sequence Mapping Voltage mapping( Substrate / Fractionated electrogram ) Entrainment Mapping Miscellaneous Klein LS, Shih H-T, Hackett FK, Zipes DP, Miles WM. Radiofrequency catheter ablation of ventricular tachycardia in patients without structural heart disease. Circulation 1992; 85: 1666–74 Pace mapping to locate tachycardia sources by stimulating at different endocardial sites to reproduce clinical tachycardia characteristics Manipulation of mapping catheter to region of origin of tachycardia Pace at this site at same cycle length as tachycardia Greater the concordance b/w tachycardia and morphology during pacing - closer exit site Klein LS, Shih H-T, Hackett FK, Zipes DP, Miles WM. Radiofrequency catheter ablation of ventricular tachycardia in patients without structural heart disease. Circulation 1992; 85: 1666–74 Look for 12/12 match More useful in ventricular tachycardia as QRS morphology easier to compare Allows to home in on region of interest - cannot pinpoint site for ablation Does not require tachycardia to sustain over a longer time Pace Map 12/12 Match Klein LS, Shih H-T, Hackett FK, Zipes DP, Miles WM. Radiofrequency catheter ablation of ventricular tachycardia in patients without structural heart disease. Circulation 1992; 85: 1666–74 Activation sequence mapping Required to pinpoint focus of tachycardia During tachycardia - mapping catheter explores endocardium - to identify site where earliest electrogram relative to a fixed reference is recorded Suitable site Local electrogram precedes any other activity One from which any movement results in a later electrogram One at which unipolar electrogram shows a sharp initial negative deflection Klein LS, Shih H-T, Hackett FK, Zipes DP, Miles WM. Radiofrequency catheter ablation of ventricular tachycardia in patients without structural heart disease. Circulation 1992; 85: 1666–74 To create activation map- points are color-coded white and red for earliest electrical activation areas orange, yellow, green, blue and purple for progressively delayed activation areas Between these points-colors are interpolated and adjoining triangles are colored with these interpolated values Propagation map Activation sequence in mapped chamber can also be represented as propagation map in which whole chamber is blue and electrical activation waves are seen in red, spreading throughout chamber as a loop(manually done in ENSITE) Substrate( Voltage) Mapping Scarred Myocardium has Low Voltage 0.5 mV or Less - Dense Scar 0.5 – 1.5 mV - Borderline Zone > 1.5 mv - Normal area McClelland JH, Wang X, Beckman KJ, Hazlitt HA, Prior MI, Nakagawa H et al. Radiofrequency catheter ablation of right atriofascicular (Mahaim) accessory pathways guided by accessory pathway activation potentials. Circulation 1994;89:2655–66. Voltage mapping Also color-coded Red as lowest amplitude and orange, yellow, green, blue and purple indicating progressively higher amplitudes Myocardial scars are seen as low voltage - and their delineation may help in understanding location of arrhythmia Entrainment mapping Allows confirmation of Reentry Allows localization of circuit and isthmus Entrainment is a continuous resetting of a reentrant circuit by a series of stimuli McClelland JH, Wang X, Beckman KJ, Hazlitt HA, Prior MI, Nakagawa H et al. Radiofrequency catheter ablation of right atriofascicular (Mahaim) accessory pathways guided by accessory pathway activation potentials. Circulation 1994;89:2655–66. Criteria for Entrainment 1. 2. 3. 4. Constant fusion during overdrive pacing except for last paced beat which is entrained but not fused Progressive fusion during overdrive pacing Localized conduction block to a site for 1 paced beat associated with interruption of tachycardia, followed by activation of that site by next paced beat from a different direction and with a shorter conduction time During pacing at 2 different rates during tachycardia- change in conduction time and EGM morphology at electrode recording site (equivalent of demonstrating progressive fusion - second criterion - with intracardiac electrogram recordings). McClelland JH, Wang X, Beckman KJ, Hazlitt HA, Prior MI, Nakagawa H et al. Radiofrequency catheter ablation of right atriofascicular (Mahaim) accessory pathways guided by accessory pathway activation potentials. Circulation 1994;89:2655–66 Entrainment results in a fusion complex Pacing stopped-last one entrained but goes round circuit-morphology similar to original rhythm If pacing CL progressively shortened circuit is invaded to a greater extent-fusion increases A premature paced beat collides with head and tail-fails to propagate Next beat is purely paced and R is activated from a different direction Manifest entrainment- demonstration of resetting with fusion Concealed entrainment- failure to demonstrate fusion but PPI equal to tachycardia cycle length-site protected isthmus PPI equal to TCL (within 20-30 ms)if pacing site within reentrant circuit Post pacing interval-interval b/w last pacing stimulus that entrained tachycardia and next recorded EGM at pacing site Manifest Entrainment with Fusion Premature impulse invade tachycardia circuit.In antidromic direction it collides and extinguishes reentrant wavefront. In orthodromic direction it creates a new wavefront(resets). Concealed Fusion Antidromic wave front does not contribute much to morphology of tachycardia beat Area of slow conduction : Isthmus Concealed Fusion Post Pacing Interval If paced from the critical Isthmus PPI = TCL Determining Pacing Site How to Determine if the Pacing Site is Within the Circuit Post Pacing Interval QRS Configuration during Entrainment S-QRS Interval During Entrainment with Concealed Fusion Stevenson Et al. Entrainment Techniques for Mapping Atrial and Ventricular Tachycardias. JCE 6(3) March 1995; 201-216 Post Pacing Interval Pace at rates slightly faster than TCL - measure local activation time from last paced beat to local EGM at pacing site Indication of proximity of pacing site to reentry circuit - time from stimulus to next nonstimulated depolarization PPI for ischemic VT should be within 30ms 20ms in atrial flutter circuits McClelland JH, Wang X, Beckman KJ, Hazlitt HA, Prior MI, Nakagawa H et al. Radiofrequency catheter ablation of right atriofascicular (Mahaim) accessory pathways guided by accessory pathway activation potentials. Circulation 1994;89:2655–66. Types of mapping site Types of Mapping Sites Remote Bystanders Adjacent Bystanders Outer Loop Sites Exit Site Central, Proximal, and Inner Loop Sites Albert L. Waldo. Heart Rhythm (2004) 1, 94–106 Remote Bystander Entrains with QRS fusion Post Pacing Interval exceeds the Tachycardia Cycle length Vishal Luther, Michael Koa-Wing. Ventricular Tachycardia Ablation in the Post Infarct Patient. http://bhrs.com/editorial-vt-ablation-in-the-post-infarct-patient Adjacent Bystander Pacing entrains tachycardia with concealed fusion. PPI does not approximate TCL S-QRS interval during entrainment does not match electrogram QRS interval during tachycardia Vishal Luther, Michael Koa-Wing. Ventricular Tachycardia Ablation in the Post Infarct Patient. http://bhrs.com/editorial-vt-ablation-in-the-post-infarct-patient Outer Loop Sites PPI matches TCL Pacing at these sites produce QRS fusion Vishal Luther, Michael Koa-Wing. Ventricular Tachycardia Ablation in the Post Infarct Patient. http://bhrs.com/editorial-vt-ablation-in-the-post-infarct-patient Exit Site Pacing produces entrainment with concealed fusion PPI matches TCL S-QRS interval < 30% of TCL Stevenson Et al. Entrainment Mapping. JACC 29 (6) May 2007: 1180-9 Central, Proximal, and Inner Loop Sites As the pacing site is moved further from the exit to more proximal sites the SQRS interval increases. If the S-QRS interval is >31-50% of the tachycardia cycle length they are designated as central sites 51-70% of the tachycardia cycle length they are designated as proximal sites >70% of the tachycardia cycle length they are designated as Inner Loop sites Stevenson Et al. Entrainment Mapping. JACC 29 (6) May 2007: 1180-9 McClelland JH, Wang X, Beckman KJ, Hazlitt HA, Prior MI, Nakagawa H et al. Radiofrequency catheter ablation of right atriofascicular (Mahaim) accessory pathways guided by accessory pathway activation potentials. Circulation 1994;89:2655–66. Advanced mapping systems Electro anatomic mapping-CARTO system Metal coil placed in a magnetic field Catheter contains a location sensor in tip 3D map created by placing catheter in known anatomic positions Local electrogram at each point superimposed on anatomical map to give a color coded activation map Non contact mapping-ENSITE Multi electrode array probe with 64 non contact electrodes Endocardial boundaries defined with conventional mapping catheter 3D Endocardial potential map created from single cardiac cycle McClelland JH, Wang X, Beckman KJ, Hazlitt HA, Prior MI, Nakagawa H et al. Radiofrequency catheter ablation of right atriofascicular (Mahaim) accessory pathways guided by accessory pathway activation potentials. Circulation 1994;89:2655–66. Basket catheter Ensite array Magnetic navigation system Ablation catheter guided and positioned by magnetic fields to a desired site within cardiac chamber 3D anatomical mapping system Newer techniques -- 3D Creating and displaying 3D image of heart chambers Displaying in multiple colors activation sequence of electrical signals of heart chambers Visualizing physical point of origin of arrhythmia accurately ADVANTAGE OF 3D Managing complex arrhythmias, postoperative cases with altered anatomy and single beat nonsustained arrhythmias ENSITE CARTO RMP Site of placement of electrodes Anatomical shell Following selection of anatomic reference - mapping catheter positioned in mapping chamber under fluoroscopic guidance Catheter initially positioned at known anatomic points - serve as landmarks for electroanatomic map eg:to CS os map right atrium, points such as SVC, IVC, His and Catheter tip advanced slowly along different walls Analysis of anatomic position of these points generate real-time 3-D models on a monitor display Selected points connected by lines to form several adjoining triangles in a global model of chamber RA anatomical chamber LA anatomical mapping LA anatomical mapping Bi-atrial anatomical chamber LV Anatomical shell Biatrial anatomical chamber LA mapping :-Earliest activation from the RSPV LA mapping :- Earliest activation from the RSPV RVOT VT activation CARTO Combined electroanatomic means of mapping cardiac arrhythmias Patient is positioned over a tripod emitting three electromagnetic waves at unique frequencies Each beam is registered by one of three specifically tuned coils embedded in mapping catheter tip to specify location in 3D space CARTO An electrogram recorded at that site is thereby archived within that positional context Direction of catheter tip, along with its pitch, yaw, and roll altitude creates a orientation vector Local tissue activation at each successive recording site produces activation maps within framework of acquired surrogate geometry CARTO principle magnetic mapping Carto catheter position Carto CARTO view from all postions RMP Mapping System based on ultrasound-distance ranging. Real-time Position Management Three catheters-fitted with microtransducerspositioned into right ventricle and coronary sinuswith a third catheter used as a roving ablation or mapping catheter Newer Modalities NavX RHYTHMIA REMOTE NAVIGATION SYSTEMS REAL TIME IMAGING M