Idiopathic ventricular tachycardia


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Idiopathic VT refers to VT occurring in structurally normal hearts in the absence of myocardial scarring. Classification of monomorphic idiopathic VT includes outflow tract VT, fascicular VT, papillary muscle VT,annular VT, and miscellaneous (VT from the body of the RV and crux of
the heart). It is commonly seen in young patients and usually has a benign course. The 12-lead lectrocardiogram is critical in distinguishing the specific form and locations of idiopathic VT. Treatment options include medical therapy specific to the underlying mechanism of VT or catheter

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Idiopathic ventricular tachycardia

  1. 1. Ramachandra
  2. 2. IVT refers  structurally normal hearts.  Young patients  Benign course  focal  Monomorphic  No scar  12-lead ECG extremely useful  Treatment :reassurance, medical therapy, and catheter ablation.
  3. 3.  Prevalence estimates accounted for 7%-38% of all patients referred for VT  Realistic estimation is closer to 10%.
  4. 4.  RVOT Tachycardia  LVOT/Aortic Cusp Tachycardia  Epicardial Outflow Tract VT Mechanism triggered activity due to catecholamine-mediated delayed after-depolarizations.This triggered activity results from a catecholamine-mediated increase in cyclic adenosine monophosphate, with subsequent increase in intracellular calcium from the sarcoplasmic reticulum, resulting in delayed after-depolarizations and triggered activity. This underlying mechanism leads to tachycardia initiation with catecholamines and termination with adenosine, -blockers, or calcium channel blockers.
  5. 5.  most common IPVT-70%  LBBB/Inf axis  F>X2M  triggered by exercise or stress, and may also occur during hormonal cycles in women  third to fifth decade of life  C/F: palpitations/chest pain, fatigue, and presyncope or syncope/isolated PVCs/nonsustained VT/sustained VT.
  6. 6.  10%-15% of IPVT,M>F  Anatomy Noncoronary cusp does not directly contactventricular myocardium, ventricular arrhythmias are rare. The base of the left and right coronary cusps lies in direct contact to the ventricular myocardium, and LV muscle fibers may extend into the aortic root,serving as a source of these PVCs. These extensions may be a remnant from embryonic development, and these myocardial fibers persist providing an arrhythmogenic substrate. When mapping more inferiorly in the aortic root, successful ablation may be related to necrosis of ventricular myocytes arising from the most superior portion of the ostium of the LV.
  7. 7. LBBB /inferior axis/ precordial transition earlier than their RVOT-VT . The precordial R-wave transition typically occurs at or before lead V3. VT originating from the left.coronary cusp has an earlier R-wave transition (typically by V1/2) than the right coronary cusp (V2/3). A broader R-wave duration (_0.5 ms) and a taller R/S-wave Amplitude in V1 and V2 favor aortic cusp location.When the precordial transition occurs at lead V3, a precordial transition earlier than sinus rhythm transition is suggestive of LVOT-VT.
  8. 8.  Idiopathic left fascicular VT= fascicular VT=LBB- ANT/POST  ECG classify to left posterior fascicular VT, left anterior fascicular VT, and left upper septal VT.  LPFVT- most common then LAFVT & septal is rare  young male(60%)- 15 and 40 years, younger female.  paroxysmal  Exertion.  Symptoms – palpitations/syncope /tachycardia- mediated cardiomyopathy .
  9. 9.  RBBB/LAD/ VT induced by atria pacing.  Verapamil sensitive  tachycardia originates from the Purkinje network of the  mechanism of verapamil-sensitive left VT is reentry/induced, entrained, and terminated by ventricular or atrial stimulation. The proposed reentrant circuit consists of an area of slow conduction that forms the orthodromic limb in the LV septum from base to apex, with the retrograde limb using the Purkinje network  false tendons is arrythmogenic.
  10. 10.  RBBB/left superior axis pattern/narrow/confused for SVT  LPFT - RBBB and left axis deviation(LAFB)  LAFT-RBBB/RAD(LFBB)  septal VT demonstrates an incomplete RBBB and normal axis.
  11. 11.  Excellent prognosis  Medical Therapy Intravenous verapamil is effective for acute termination. Chronic oral verapamil therapy is often an effective regimen for patients with symptoms who do not wish to pursue catheter ablation.-adrenergic blockers have also been used with some success.  Catheter Ablation: successful-90%,
  12. 12.  2008, Doppalapudi et al. first to report idiopathic VT from posterior PM  Posterior papillary muscle origin is more common. Papillary muscle VT is usually exercise induced and is catecholamine sensitive, requiring isoproterenol or epinephrine for induction  mechanism is typically focal in nature and not reentrant. This VT cannot be entrained, and has a lack of late potentials at the site of ablation.  Papillary muscle VT often exhibits multiple QRS morphologies, with subtle changes seen spontaneously or during ablation. These subtle morphologic changes are thought to be from preferential conduction to different exit sites or multiple regions of origins within the complex structure of the papillary muscles.  RFA-quite usuful.
  13. 13.  majority from anterior mitral annulus  ECG in MAVT:RBBB pattern/ monophasic R or Rs in leads V2-V6.  Catheter ablation is highly successful with ablation delivered at the site of earliest ventricular activation or sites with a 12/12 pace-map match by mostly endocardial approach or coronary venous system(GCV)
  14. 14.  8% of IPVT  5% of right-sided VT  Septal sites > free-wall sites  septal locations-anteroseptal or para-Hisian.  ECG: A positive component (any r or R) was recorded in lead aVL in 95% of patients  QRS duration and Q-wave amplitude V1-V3 were greater in VT/PVCs arising from the free wall of the tricuspid annulus compared with the septum. Notching of the QRS complex was seen more often in free-wall sites, as well as later precordial transition. A Q-wave in lead V1 was observed more often in septal tricuspid annular VTs.  RF catheter ablation successful for the free wall (90%) compared with the septal (57%) group. Low success rate in the septal tricuspid annular group was thought to be due to the likelihood of impairing AV nodal conduction with RF ablation.
  15. 15.  Van Herendael reported 278 IPVT from 10% -lower RV body. 48% -Within 2 cm of the tricuspid annulus 28% -Basal RV 24% -the apical RV.  VT/PVC from the RV free wall had a longer QRS duration and deeper S-wave in lead V2/V3.  Apical VT/PVC more often had precordial R-wave transition V6, smaller R-waves in lead II, and an S-wave in aVR.  RF catheter ablation was acutely successful in 96% of patients.
  16. 16.  Doppalapudi described 4/340 patients referred for IPVT  Epicardial , junction of the middle cardiac vein and the coronary sinus  Sustained / syncope or presyncope  Induced/timulation or burst pacing from the RV, and often required Isoproterenol  ECG demonstrates a leftward superior axis QRS morphology with an early precordial transition and delayed intrinsicoid deflection.  EP study: The earliest activation was present in the middle cardiac vein. Coronary angiography demonstrated the site of earliest activation within 5-10 mm of the proximal posterior descending artery or proximal coronary sinus  Ablation from the coronary sinus or middle cardiac vein was attempted in all, but was successful in only one.Percutaneous epicardial ablation was attempted in two of the remaining three, and successfully abolished VT in both.