PREMATURE VENTRICULAR COMPLEX: DIAGNOSIS AND MANAGEMENT

PVC LOCALIZATION AND MANAGEMENT
WHEN TO ABLATE?

1. PREMATURE VENTRICULAR COMPLEX AND CATHETER ABLATION AJAY PRATAP SINGH DEPARTMENT OF CARDIOLOGY DR. RAM MANOHAR LOHIA HOSPITAL, NEW DELHI.

2. DEFINITION Premature V entricular C omplex: It is an early ventricular depolarization with or without mechanical contraction. 2019 HRS guidelines catheter ablation of ventricular arrythmia recommends avoiding the use of the terms “ventricular premature depolarization” and “premature ventricular contraction” to standardize the literature and acknowledge that early electrical activity does not necessarily lead to mechanical contraction Assessment and treatment of VPCs is challenging and complex and is highly dependent on the clinical context. The prognostic significance of VPCs is variable and, again, best interpreted in the context of the underlying cardiac condition. Cronin EM, Bogun FM, Maury P, et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias.  Heart Rhythm . 2020;17(1):e2-e154. doi:10.1016/j.hrthm.2019.03.002

3. PATHOPHYSIOLOGY Three common mechanisms exist for VPCs, (1) automaticity, (2) reentry, and (3) triggered activity Automaticity : This is the development of a new site of depolarization in non-nodal ventricular tissue, which can lead to a VPC. A utomaticity is most probable with electrolyte abnormalities or acute ischemia and is enhanced by catecholamines. These conditions tend to lower the diastolic transmembrane voltage, resulting in premature depolarization. Reentry Circuit : Reentry typically occurs when slow-conducting tissue ( eg , infarcted myocardium) is present adjacent to normal tissue. Most common mechanism for PVC’s in patients with SHD. Triggered activity : After depolarizations triggered by a preceding impulse can lead to premature activation if the threshold is reached, and this can cause a VPC. Afterdepolarization can occur either during (early) or after (late) completion of repolarization.

4. ETIOLOGY CARDIAC CAUSES Acute myocardial infarction Valvular heart disease, especially mitral valve prolapse Cardiomyopathy ( eg , ischemic, dilated, hypertrophic, infiltrative) Myocardial stretch Cardiac contusion Bradycardia Tachycardia (high-catecholamine state) NON-CARDIAC CAUSES Electrolyte disturbances (hypokalemia, hypomagnesemia, or hypercalcemia) Medications ( eg , digoxin, tricyclic antidepressants, aminophylline, amitriptyline, pseudoephedrine, fluoxetine) Other drugs ( eg , cocaine, amphetamines, caffeine, alcohol) Anesthetics Surgery Infection Stress

5. PREVELANCE The prevalence of VPCs is directly related to the study population, the detection method, and the duration of observation. In one of the first large population-based assessments performed in 1962, a study of 122 043 US Air Force personnel showed that 7.8 per 1000 exhibited a PVC during a 48-second ECG, with an increasing prevalence with age. [1] The Framingham heart study (with 1-h ambulatory ECG) suggested that the prevalence rate of 1 or more VPCs per hour was 32% in women and 33 % in men without coronary artery disease (CAD). Among patients with CAD, the prevalence rate of 1 or more VPCs was 58% in men and 49% in women. [2] In the ARIC study, a 2-minute ECG detected PVCs in 5.5% of the population.[3] [1]Hiss RG, Lamb LE . Electrocardiographic findings in 122,043 individuals. Circulation . 1962; 25:947–961. doi : 10.1161/01.cir.25.6.947 [2] Bikkina M, Larson MG, Levy D . Prognostic implications of asymptomatic ventricular arrhythmias: the Framingham Heart Study. Ann Intern Med . 1992; 117:990–996. doi : 10.7326/0003-4819-117-12-99 [3] Agarwal SK, Simpson RJ, Rautaharju P, Alonso A, Shahar E, Massing M, Saba S, Heiss G . Relation of ventricular premature complexes to heart failure (from the Atherosclerosis Risk In Communities [ARIC] Study). Am J Cardiol . 2012; 109:105–109. doi : 10.1016/j.amjcard.2011.08.009

6. Studies using 24-hour ambulatory monitoring showed a VPC prevalence rate of 41% in healthy teenage boys aged 14-16 years, 50-60% in healthy young adults, and 84% in healthy elderly persons aged 73-82 years. Incidence of PVC will likely become more of a common phenomenon as longer monitoring devices are used. The direct-to-consumer wearables with ECG capabilities, such as the Apple Watch and the Alivecor Kardia device, will only produce more strips revealing these early ventricular beats for clinicians to consider. T he common use of wearable patch ECG monitoring, Heckbert et al recently described their findings after fitting 1122 MESA (Multi-Ethnic Study of Atherosclerosis) participants with Zio patches ( iRhythm Technologies), observing at least 1 PVC in 99.5% of those elderly (mean age of 75 years) individuals. They describe a median PVCcount of 1.9/hour Heckbert SR, Austin TR, Jensen PN, Floyd JS, Psaty BM, Soliman EZ, Kronmal RA . Yield and consistency of arrhythmia detection with patch electrocardiographic monitoring: the Multi-Ethnic Study of Atherosclerosis. J Electrocardiol . 2018; 51:997–1002. doi : 10.1016/j.jelectrocard.2018.07.027

7. CLASSIFICATION OF PVC Lown classification

8. PREDICTORS OF PVC Marcus GM. Evaluation and Management of Premature Ventricular Complexes.  Circulation . 2020;141(17):1404-1418. doi:10.1161/CIRCULATIONAHA.119.042434 UNAVOIDABLE RISK FACTOR AVOIDABLE RISK FACTOR advancing age and a taller height. higher blood pressure, less physical activity, and smoking.

9. PRESENTATION Patients with PVCs typically come to clinical attention for 1 of 2 reasons: symptoms or an incidental finding on medical examination. Symptoms may include palpitations (which may manifest as chest discomfort, a sensation of an intermittently strong heartbeat, or a sensation of skipped or irregular heartbeats), presyncope, dyspnea, and fatigue . The symptom is often not attributable to the PVC itself, but rather the sensation of the particularly strong heartbeat that occurs because of the prolonged ventricular filling time after that PVC, resulting in an enhanced stroke volume along the Frank- Starling curve and potentiated calcium release. VPCs rarely cause true hemodynamic compromise, except when they occur frequently in a patient with severely depressed left ventricular function or when they are associated with an underlying bradycardia.

10. Patients may rarely present with abrupt syncope or sudden arrhythmic death attributable to PVC-induced ventricular fibrillation. [1] Although there are no established guidelines to identify patients with PVC at the highest risk of PVC triggered ventricular fibrillation, the clinical pearl is to consider PVCs as potentially playing a causal role when ventricular fibrillation is observed. A family history is important to elucidate any possible inherited disorders that may be associated with PVCs and a risk for sudden death. Examination: VPCs frequently are associated with variable or decreased intensity of heart sounds , Bounding jugular pulse (cannon a wave) from a loss of atrioventricular (AV) synchrony may be present. [1] Singh P, Noheria A . ablation approaches for ventricular fibrillation. Curr Treat Options Cardiovasc Med . 2018; 20:21. doi : 10.1007/s11936-018-0612-4

11. Agarwal SK, Simpson RJ Jr, Rautaharju P, et al. Relation of ventricular premature complexes to heart failure (from the Atherosclerosis Risk In Communities [ARIC] Study).  Am J Cardiol . 2012;109(1):105-109. doi:10.1016/j.amjcard.2011.08.009

12. Ataklte F, Erqou S, Laukkanen J, Kaptoge S. Meta-analysis of ventricular premature complexes and their relation to cardiac mortality in general populations.  Am J Cardiol . 2013;112(8):1263-1270. doi:10.1016/j.amjcard.2013.05.065

13. Ataklte F, Erqou S, Laukkanen J, Kaptoge S. Meta-analysis of ventricular premature complexes and their relation to cardiac mortality in general populations.  Am J Cardiol . 2013;112(8):1263-1270. doi:10.1016/j.amjcard.2013.05.065

14. Agarwal V, Vittinghoff E, Whitman IR, Dewland TA, Dukes JW, Marcus GM. Relation Between Ventricular Premature Complexes and Incident Heart Failure.  Am J Cardiol . 2017;119(8):1238-1242. doi:10.1016/j.amjcard.2016.12.029

15. PVC INDUCED CARDIOMYOPATHY Frequent PVCs (usually defined as >10–15% of the total number of beats per 24 h) can impair LV function (PVC-induced cardiomyopathy).[1] However, it is well recognized that not all patients with frequent PVCs will develop LV dysfunction. Factors associated with the development of LV dysfunction include[2] longer PVC QRS duration, epicardial PVCs, retrograde atrial activation of PVCs, interpolation of PVC [1]Al-Khatib SM, Stevenson WG, Ackerman MJ, Bryant WJ, Callans DJ, Curtis AB et al. AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation 2017;138:e272–391. [2] Arnar DO, Mairesse GH, Boriani G, et al. Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS) [published online ahead of print, 2019 Mar 18].  Europace . 2019;euz046. doi:10.1093/ europace /euz046

16. Arnar DO, Mairesse GH, Boriani G, et al. Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS) [published online ahead of print, 2019 Mar 18].  Europace . 2019;euz046. doi:10.1093/ europace /euz046

17. Arnar DO, Mairesse GH, Boriani G, et al. Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS) [published online ahead of print, 2019 Mar 18].  Europace . 2019;euz046. doi:10.1093/ europace /euz046

18. Arnar DO, Mairesse GH, Boriani G, et al. Management of asymptomatic arrhythmias: a European Heart Rhythm Association (EHRA) consensus document, endorsed by the Heart Failure Association (HFA), Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), Cardiac Arrhythmia Society of Southern Africa (CASSA), and Latin America Heart Rhythm Society (LAHRS) [published online ahead of print, 2019 Mar 18].  Europace . 2019;euz046. doi:10.1093/ europace /euz046

19. ELECTROCARDIGRAPHY The diagnosis of VPCs is typically established by electrocardiography. The presence of a VPC on a 12-lead ECG provides essential information about the site-of origin of the VPC. Accordingly, an ECG should be performed to look for pathophysiologic cardiac abnormalities as well as documenting the presence of VPCs and potentially providing information about their specific mechanism and frequency. 1-QRS duration of more than 120 msec. 2-Bizarre morphology that does not resemble usual aberration ( ie , typical RBBB/typical LBBB). 3-T wave in the opposite direction from the main QRS vector. 4-A fully compensatory pause ( ie , the PP interval surrounding the VPC is twice the sinus PP interval); less frequently, the VPC is interpolated and does not alter the baseline sinus interval ( ie , the PP interval surrounding the VPC is equal to the sinus PP interval)

20. LOCALIZATION OF VPC PVC usually origin from Right Ventricle outflow tact ( 7 0%–80% ) Non RVOT ( 10%–15% )(three papillary muscles, moderator band and tricuspid annulus) Left ventricle outflow tract ( 15%–25%) Left ventricle papillary muscles(AL & PM) Epicardial (AIV/GCV junction or LV summit) ( ≈12%) Free wall Right PSC Left PSC Posterior septum Para HISian Right coronary cusp LCC/RCC Left coronary cusp AMC LV summit Mitral annulus (AL)

21. Anderson RD, Kumar S, Parameswaran R, et al. Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms.  Circ Arrhythm Electrophysiol . 2019;12(6):e007392. doi:10.1161/CIRCEP.119.007392

22. Anderson RD, Kumar S, Parameswaran R, et al. Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms.  Circ Arrhythm Electrophysiol . 2019;12(6):e007392. doi:10.1161/CIRCEP.119.007392

23. Anderson RD, Kumar S, Parameswaran R, et al. Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms.  Circ Arrhythm Electrophysiol . 2019;12(6):e007392. doi:10.1161/CIRCEP.119.007392

24. Anderson RD, Kumar S, Parameswaran R, et al. Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms.  Circ Arrhythm Electrophysiol . 2019;12(6):e007392. doi:10.1161/CIRCEP.119.007392

25. Anderson RD, Kumar S, Parameswaran R, et al. Differentiating Right- and Left-Sided Outflow Tract Ventricular Arrhythmias: Classical ECG Signatures and Prediction Algorithms.  Circ Arrhythm Electrophysiol . 2019;12(6):e007392. doi:10.1161/CIRCEP.119.007392

26. Noheria A, Deshmukh A, Asirvatham SJ. Ablating Premature Ventricular Complexes: Justification, Techniques, and Outcomes.  Methodist Debakey Cardiovasc J . 2015;11(2):109-120. doi:10.14797/mdcj-11-2-109

27. Cronin EM, Bogun FM, Maury P, et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias [published correction appears in Europace . 2019 Aug 1;21(8):1144] [published correction appears in J Arrhythm . 2020 Jan 12;36(1):214].  Europace . 2019;21(8):1143-1144. doi:10.1093/ europace /euz132

28. FIRST EVIDENCE OF PVC FOLLOW UP.

29. S uccessful PVC suppression could result in an increased risk for death as in CAST (Cardiac Arrhythmia Suppression Trial), the notion that PVCs were causal, or at least should be considered a reasonable target of suppression for the purposes of improving prognosis, was abandoned.

30. In 1995, this trial showed that PVC suppression may have mortality benefit and increases LVEF in long term.

31. Subsequently, starting in the early 2000s, case reports of successful catheter ablation of PVCs resulting in improvements in and even complete resolution of systolic dysfunction were published.[1] Soon case series of improvements in LVEF after catheter ablation among patients with a high burden of PVCs and reduced left ventricular systolic function, providing evidence that PVCs could play a causal role in heart failure [1] Chugh SS, Shen WK, Luria DM, Smith HC. First evidence of premature ventricular complex-induced cardiomyopathy: a potentially reversible cause of heart failure.  J Cardiovasc Electrophysiol . 2000;11(3):328-329. doi:10.1111/j.1540-8167.2000.tb01802.x

32. Sekiguchi Y, Aonuma K, Yamauchi Y, et al. Chronic hemodynamic effects after radiofrequency catheter ablation of frequent monomorphic ventricular premature beats.  J Cardiovasc Electrophysiol . 2005;16(10):1057-1063. doi:10.1111/j.1540-8167.2005.40786.x Bogun F, Crawford T, Reich S, et al. Radiofrequency ablation of frequent, idiopathic premature ventricular complexes: comparison with a control group without intervention.  Heart Rhythm . 2007;4(7):863-867. doi:10.1016/j.hrthm.2007.03.003

33. MANAGEMENT R eassurance is the most useful tool for the patient with PVCs, additional management beyond reassurance should be pursued, 3 key pieces of information are needed: (1) information regarding symptoms, (2) the burden of the PVCs (typically reported in PVCs as a percentage of all beats), and (3) the presence or absence of structural heart disease. Lifestyles changes to avoid smoking , caffeinated drinks consumption (evidence is mixed for its benefit currently a RCT CRAVE trial is ongoing on for the same) If a patient has bothersome symptoms despite reassurance or a reduced LVEF, either medical treatment or catheter ablation are reasonable first options. Marcus GM. Evaluation and Management of Premature Ventricular AComplexes .  Circulation . 2020;141(17):1404-1418. doi:10.1161/CIRCULATIONAHA.119.042434

34. MEDICAL MANAGEMENT Either β-blockers or nondihydropyridine calcium channel blockers (diltiazem or verapamil) are considered first-line medicines for PVCs. R andomized controlled clinical trials demonstrate that β-blockers result in a clinically meaningful reduction in symptomatic outflow tract PVCs by 12% to 24% [1] and CCB especially for fascicular VT [2] For the patient in need of treatment who strongly prefers to avoid catheter ablation, for whom catheter ablation has failed, or who may not be a good ablation candidate (because of frailty or multifocal PVCs), additional antiarrhythmic drugs to consider include flecainide, propafenone, sotalol, and amiodarone. Flecainide and propafenone are generally considered contraindicated in the presence of coronary disease, severe left ventricular hypertrophy, or heart failure. Sotalol can suppress PVCs in most patients but with careful observation for QT prolongation and is a particularly reasonable choice in the presence of CAD and amiodarone is reserved for older patients. [1] Krittayaphong R, Bhuripanyo K, Punlee K, Kangkagate C, Chaithiraphan S . Effect of atenolol on symptomatic ventricular arrhythmia without structural heart disease: a randomized placebo-controlled study. Am Heart J . 2002; 144:e10. doi : 10.1067/mhj.2002.125516 [2] Belhassen B, Horowitz LN . Use of intravenous verapamil for ventricular tachycardia. Am J Cardiol . 1984; 54:1131–1133.  doi : 10.1016/s0002-9149(84)80158-7

35. Fr equent symptomatic VPBs from the >6000 VPBs per 24 hours on Holter monitoring. METOPROLOL (12.5-25mg) PROPAFENONE (100 mg BD)

36. Cronin EM, Bogun FM, Maury P, et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias [published correction appears in Europace . 2019 Aug 1;21(8):1144] [published correction appears in J Arrhythm . 2020 Jan 12;36(1):214].  Europace . 2019;21(8):1143-1144. doi:10.1093/ europace /euz132

37. CATHETER ABLATION: CHANGE IN GUIDELINES European Heart Rhythm Association; Heart Rhythm Society, Zipes DP, et al. ACC/AHA/ESC 2006 guidelines for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: a report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death).  J Am Coll Cardiol . 2006;48(5):e247-e346. doi:10.1016/j.jacc.2006.07.010 Cronin EM, Bogun FM, Maury P, et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias [published correction appears in Europace . 2019 Aug 1;21(8):1144] [published correction appears in J Arrhythm . 2020 Jan 12;36(1):214].  Europace . 2019;21(8):1143-1144. doi:10.1093/ europace /euz132

38. In BrS , VF-triggering premature ventricular complexes (PVCs) are almost identical, site specific, and predominantly originate from the right ventricular outflow tract (RVOT) Talib AK, Nogami A. Catheter Ablation for Brugada Syndrome.  Korean Circ J . 2020;50(4):289-301. doi:10.4070/kcj.2019.0344

39. PVCs are evident, the origin is usually from one of the three regions of fibro-fatty replacement in the “triangle of dysplasia” (i.e., right ventricular outflow tract, apex, and infundibulum).

40.  isthmus 1 bordered by tricuspid annulus and right ventricular outflow tract patch/right ventricular incision isthmus 2 by right ventricular incision and pulmonary valve  isthmus 3 by pulmonary valve and ventricular septal defect patch  isthmus 4 by ventricular septal defect patch and tricuspid annulus Cronin EM, Bogun FM, Maury P, et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias [published correction appears in Europace . 2019 Aug 1;21(8):1144] [published correction appears in J Arrhythm . 2020 Jan 12;36(1):214].  Europace . 2019;21(8):1143-1144. doi:10.1093/ europace /euz132

41. PACES/HRS expert consensus statement on the recognition and management of arrhythmias in adult congenital heart disease.  Can J Cardiol . 2014;30(10):e1-e63. doi:10.1016/j.cjca.2014.09.002

42. Recent studies have shown that PVC burden is an independent predictor of VT in HCM patients apart from already defined risk factors

43. PROCEDURAL PLANNING FOR CA A proper preprocedural risk stratification is crucial to minimize the risk of adverse periprocedural outcomes such as acute hemodynamic decompensation (AHD), which can have devastating consequences A score between 9-14 has a 6% risk of acute hemodynamic collapse and score ≥ 15 has a risk increased to 24% during procedure. Santangeli P, Muser D, Zado ES, et al. Acute hemodynamic decompensation during catheter ablation of scar-related ventricular tachycardia: incidence, predictors, and impact on mortality.  Circ Arrhythm Electrophysiol . 2015;8(1):68-75. doi:10.1161/CIRCEP.114.002155

44. PRE-PROCEDURE PREPARATION AADs, except for amiodarone, should possibly be discontinued for at least 5 half-lives prior to the ablation procedure. Oral anticoagulants are generally discontinued prior to the ablation to achieve an international normalized ratio within 1.5 at the time of the study Direct oral anticoagulants should be withheld for 24–48 hours before the procedure, depending on anticipated access, and bridging with heparin can be used for patients with mechanical heart valves or other features that place them at high risk of thrombosis.

45. Unfractionated heparin is commonly administered after sheath insertion as an initial bolus (empirical dose 5000– 10,000 IU or 50–100 IU/kg ) followed by intermittent bolus and/or continuous infusion to maintain a target activated clotting time (ACT) longer than 250–350 seconds . Prophylactic antibiotics are NOT generally indicated for sterile procedures such as VA ablation. However, patients with ICDs undergoing ablation, in which catheters might be in direct contact with the intravascular leads, could present a special circumstance.

46. ELECTROPHYSIOLOGICAL TESTING PROGRAMMED ELECTRICAL STIULATION (PES) is a key component of the PVC ablation procedure, allowing for mapping of induced arrhythmias. In addition, a baseline assessment of arrhythmia induction can be useful by comparison for the eventual assessment of procedural outcome. For induction of PVC: in 2019 HRS guidelines 100% of experts stimulated from the RV apex, 66% from the RVOT and 59% from the LV if LV access has already been obtained. In drugs isoproterenol was used frequently (93%), followed by epinephrine (21%), phenylephrine (14%), atropine (11%), and calcium (7%). In addition, some members of the committee at least considered dobutamine and caffeine.

47. Mapping and Imaging Techniques: Catheters M ultielectrode mapping catheters , offer several advantages, particularly in respect to mapping density, resolution, and speed. The ability to record electrograms from multiple sites at each beat increases the number of data points and can shorten the duration of mapping. Multielectrode catheters allow pacing from multiple electrodes positioned in and around areas of scar. In addition pacing from one site while recording from surrounding sites allows investigation of propagation in multiple directions that can identify anisotropy and areas prone to slow conduction and/or block. The Pentaray catheter ( Biosense Webster,Diamond Bar,CA ) Livewire™ Electrophysiology Catheter Dual-Purpose Duo- Decapolar (20 electrodes)

48. Common limitations of multielectrode mapping catheters include mechanical trauma with frequent ectopy, transient injury of the superficial conduction bundles, limited maneuverability, lack of tissue contact information, and the potential for thrombus formation with the need for careful anticoagulation.

49. ACTIVATION MAPPING Activation mapping is performed by recording of local electrograms from multiple sites during a PVC. For focal PVCs, the earliest site of activation identifies the SOO and is the target of ablation. At this site, the local bipolar electrogram precedes the QRS onset, and the unipolar signal filter setting demonstrates a QS configuration , consistent with a centrifugal spread of activation away from the SOO. In scar-related re-entry circuit, the QRS activation occurs when the impulse reaches the exit from the scar to activate the contractile myocardium, In “exit sites,” electrograms can be fractionated and immediately precede the onset of the QRS complex. Ablation at exit sites can terminate the tachycardia.

50. ENTRAINMENT MAPPING Entrainment involves the continuous resetting of a reentry circuit during pacing at sites that are either within or outside the reentry circuit. This technique is used to identify critical sites of the arrhythmia circuit, through the analysis of the QRS morphology, the measured intervals, and the recorded electrograms. QRS configuration during entrainment provides information about whether the pacing site is within or outside the protected zone of the reentry circuit. With the pacing site being located outside the reentry circuit, during entrainment, the stimulated wavefronts that propagate out from the pacing site collide with the orthodromically propagating wave-front of the reentry circuit and fuse; QRS complex is due to the fusion of wavefronts propagating directly away from the pacing site with those emerging from the tachycardia circuit (classic entrainment). During pacing from within or near the reentry circui t, pacing entrains VT without changing the QRS configuration (concealed entrainment or entrainment with concealed fusion)

51. Entrainment with concealed fusion indicates that the pacing site is within a protected region of the reentry circuit, and can be located in the common pathway of the reentry circuit If pacing is performed from a site in the circuit, the stimulus-QRS interval should be equal to the electrogram-QRS interval during VT. On the other hand, if stimulation is performed from a bystander site, the stimulus-QRS interval is longer than the electrogram-QRS interval during tachycardia. A difference in stimulus-QRS and electrogram-QRS up to 30 ms was superior to other criteria for distinguishing bystander sites from critical sites in one study. The stimulus-QRS interval indicates the conduction time from the pacing site to the VT exit site. T he stimulus-QRS/VT CL ratio is a reflection of the pacing site location within the critical zone of the reentry circuit. The PPI is also an indication of the proximity of the pacing site to the reentry circuit ; the PPI measures the interval from the pacing stimulus to the following non-stimulated depolarization recorded at the pacing site. Cronin EM, Bogun FM, Maury P, et al. 2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias [published correction appears in Europace . 2019 Aug 1;21(8):1144] [published correction appears in J Arrhythm . 2020 Jan 12;36(1):214].  Europace . 2019;21(8):1143-1144. doi:10.1093/ europace /euz132

52. PACE MAPPING Pace mapping is a technique used to locate the origin of a PVC or VT by stimulating the myocardium to reproduce the clinical 12-lead morphology in the absence of VT Pace mapping can supplement activation mapping and can be particularly useful when activation mapping is not possible due to suppression of clinical PVCs The optimal site should exactly match the tachycardia QRS, including individual notches as well as major deflections Pace mapping indicates the location of the origin of focal VAs; a pacing rate close to the VT/PVC rate should be used. The stimulus to-surface QRS interval can further provide complementary information. SHORT: focus of triggered PVC is surrounded by relatively healthy myocardium LONG : arrhythmogenic tissue separated from ventricular myocardium by zones of slow conduction

53. SUBSTRATE MAPPING

54. ABLATION TECHNIQUES Unipolar Radiofrequency Catheter Ablation: R efined with the addition of temperature sensing and larger tip catheters and further with catheter tip cooling. Irrigation of the ablation electrode reduces temperature at this interface and allows greater power delivery and thus the creation of larger lesions A typical initial power setting for ablation with an open irrigated catheter in the LV is 30 watts and can be adjusted up to 50 watts to achieve an impedance drop of 10 ohms. Contact Force Sensing : Lesion size is critically dependent on the contact of the ablating electrode with the tissue; RF applications with a mean contact force .10 g are more likely to result in electrical unexcitability in scar areas Hypotonic External Irrigation : Most ablation catheter tips are 3.5–4 mm in length and are typically irrigated with 0.9% sodium chloride solution. The efficiency of delivering current to myocardial tissue can be increased by using smaller electrode tip sizes and less conductive irrigant , such as 0.45% sodium chloride Needle Ablation : A catheter with an extendable/retractable needle at the tip can function as an intramural electrode for the temperature-controlled delivery of RF energy. Infusion needle ablation has been reported as a means to achieve intramural ablation lesions.

55. Cryoablation: Have advantage of good contact and stability when compared with RF ablation, but focal cryoablation lesions are smaller and take longer to develop. Larger lesions can be created with larger tip cryoablation catheters Trans-vascular Ethanol Ablation: Creating an arterial occlusion and controlled infarction has long been used to create ventricular ablation lesions; Heart block is a frequent risk when a septal substrate is targeted. Stereotactic Radiotherapy : The use of stereotactic motion-gated external beam radiation for ablation has been explored in animal models, and its feasibility has been demonstrated in humans. This method requires the accurate pre-procedure identification of the culprit arrhythmogenic substrate, using either intracardiac mapping, imaging, or noninvasive ECGI

56. Surgical Therapy Sympathetic Modulation Endpoints of Catheter Ablation

57. POST PROCEDURE CARE The Multicenter Thermocool Ventricular Tachycardia Ablation Trial has recommended antiplatelet therapy with aspirin 325 mg/day or anticoagulation with warfarin for 3 months after ablation, if ablation has been performed over an area with > 3 cm between ablation sites Stevenson WG, Wilber DJ, Natale A, et al. Irrigated radiofrequency catheter ablation guided by electroanatomic mapping for recurrent ventricular tachycardia after myocardial infarction: the multicenter thermocool ventricular tachycardia ablation trial.  Circulation . 2008;118(25):2773-2782. doi:10.1161/CIRCULATIONAHA.108.788604

58. COMPLICATIONS Pothineni NV, Deshmukh A, Padmanabhan D, et al. Complication rates of ventricular tachycardia ablation: Comparison of safety outcomes derived from administrative databases and clinical trials.  Int J Cardiol . 2015;201:529-531. doi:10.1016/j.ijcard.2015.08.116

59. FUTURE ADVANCES IN CA Advances in Mapping : Outside of catheter mapping , tools have been created to take advantage of coronary vasculature access to intramyocardial structures. The most common example involves mapping the perforator veins facilitated by the use of electrically protected wires into septal perforating branches, the use of cold saline , and the use of dual site pace mapping to identify intramural VA origins. Entirely noninvasive electrophysiological mapping has been developed with ECGI. This technology combines body surface unipolar electrograms obtained from a vest of electrodes with patient-specific heart-torso geometry Advances in Ablation : catheter with a needle that can be deployed into ventricular myocardium to both map and ablate. Allowing more precise intramyocardial mapping, injection of dye to assess location of potential ablation using fluoroscopy, and deeper ablation lesions than standard catheter ablation. A lternative energies have been studied, locally applied pulsed field direct current electroporation , and noninvasive focused stereotactic radiatio n. Electroporation using localized direct current is a technology in rapid development with significant advantages of speed (seconds) and a tissue-selective ablation effect in preclinical models and noninvasive photon ablation .

60. Bipolar devices focus ablation energy between two closely opposed electrodes, which maintain relatively high current density Focused ablation energy causes rapid tissue temperature rise producing contiguous thermal injury Disadvantage :  difficulty of positioning and maintaining the stability of two catheters Electroporation

61. THANK YOU