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ventricular tachycardia (VT)

Ventricular tachycardia (VT) is defined as a series of >= 3 wide QRS complexes occuring at a rate >100/min resultingfrom depolarization originating in the ventricles. - it is the most frequently encountered life-threatening arrhythmia. - left untreated, VT may deteriorate into ventricular fibrillation. Classification: - sustained ventricular tachycardia lasts >= 30 seconds - non-sustained ventricular tachycardia lasts < 30 seconds - monomorphic ventricular tachycardia: - QRS complexes in same leads do not vary in morphology - polymorphic ventricular tachycardia: - QRS complexes in same leads vary in morphology - torsades de pointes is an example Etiology: 1) re-entry (monomorphic) 2) increased automaticity 3) myocardial infarction 4) drug toxicity - tricyclic antidepressants 5) electrolyte abnormalities 6) cardiomyopathy 7) infiltrative diseases a) amyloidosis b) sarcoidosis 8) infectious diseases a) viral myocarditis or cardiomyopathy b) Chagas' disease c) Lyme disease 9) congenital diseases a) inborn errors of metabolism b) long QT syndrome & torsades de pointes 10) inflammatory diseases a) systemic lupus erythematosus b) rheumatoid arthritis 11) malignancies a) primary b) metastatic 12) idiopathic Clinical manifestations: 1) patients may be asymptomatic 2) palpitations 3) neck pounding (AV dissociation) 4) dyspnea 5) light-headedness 6) angina 7) syncope & near-syncope Laboratory: - complete blood count (assess for anemia) - basic metabolic panel (assess electrolyte abnormalities) Special laboratory: 1) electrocardiogram a) wide QRS >120 ms with bizarre morphology b) ventricular rate >100/min c) p waves dissociated from QRS complex d) T-waves opposite in polarity to major QRS deflection e) EKG features that favor ventricular tachycardia over supraventricular tachycardia with aberrancy (i.e.bundle-branch block) - AV dissociation - presence of capture or fusion beats - left axis deviation - QRS duration >140 ms - precordial concordant of the major QRS deflection - factors favoring ventricular tachycardia (VT) vs right bundle branch block (RBBB) - monophasic or biphasic QRS complexes in V1 - left axis deviation - R/S ratio of <1 in V6 - factors favoring ventricular tachycardia (VT) vs left bundle branch block (LBBB) - R in V1 or V2 >30 ms in duration - any Q in V6 - onset of QRS to nadir of S >60 ms in V1 or V6 - notching of the downstroke of S in V1 or V2 2) electrophysiologic testing - not indicated in initial management of ventricular tachycardia after restoration of sinus rhythm - useful for identifying arrhythmogenic focus if ablation is considered Radiology: - cardiac magnetic resonance imaging to assess structural heart disease after restoration of sinus rhythm (initial procedure of choice) [2] Complications: - non-sustained ventricular tachycardia within 48 hours of myocardial infarction does not confer additional risk - non-sustained ventricular tachycardia within the first year after myocardial infarction outside of that 48 hour window is associated with increased mortality [2] Management: - consider drug toxicity - tricyclic antidepressants - sodium bicarbonate === sustained ventricular tachycardia === 1) hemodynamic instability - immediate DC synchronized cardioversion - pulseless ventricular tachycardia treated as ventricular fibrillation [2] 2) stable patient, chemical cardioversion a) preserved heart function 1] procainamide* 2] sotalol or other beta-blocker 3] amiodarone# 150 mg IV over 10 minutes 4] lidocaine 0.5-0.75 mg/kg IV push b) poor LV ejection fraction 1] amiodarone# 150 mg IV over 10 minutes 2] lidocaine 0.5-0.75 mg/kg IV push 3] then DC synchronized cardioversion c) prolonged QT interval - treat as torsades de pointes d) IV infusion of above agents may be indicated for recurrent sustained VT e) avoid adenosine & calcium channel blockers 3) treat ischemia, correct electrolytes - coronary revascularization alone in patients with sustained monomorphic ventricular tachycardia & coronary artery disease is unsufficient to prevent recurrent ventricular tachycardia [6] 4) follow-up after restoration of sinus rhythm a) search for ischemia 1] myocardial perfusion study 2] coronary angiography b) catheter ablation if indicated by electrophysiologic testing - combination of structural imaging & body surface mapping of ventricular tachycardia during electrophysiologic testing to guide radioablation may increase success rate to 94% [7] c) implantable cardiac defibrillator d) high risk of sudden death e) workup should be conducted as an inpatient * procainamide is the agent of choice for chemical cardioversion except in the setting of acute MI or digoxin toxicity; in these cases, lidocaine remains the agent of choice [2] # amiodarone not effective [4] === non-sustained ventricular tachycardia === 1) asymptomatic non-sustained ventricular tachycardia a) no proven antiarrhythmic treatment b) implantable defibrillator (ICD) - post-MI, LVEF < 35%, & VT inducible during electrophysiologic testing, or - implantable defibrillator otherwise indicated, i.e. heart failure (see implantable defibrillator) 2) symptomatic non-sustained ventricular tachycardia (structurally normal heart) a) beta-blockers or Ca+2-channel blocker 1st line b) amiodarone & sotalol have been used c) class 1c antiarrhythmics (flecainide, propafenone) limited to patients with coronary artery disease d) radiofrequency ablation if drug therapy fails - electrophysiology-guided cardiac radioablation [5] e) implantable defibrillator as indicated 3) symptomatic non-sustained ventricular tachycardia (structurally abnormal heart) a) rhythm control b) implantable defibrillator (ICD) [2] 4) medical treatment does not diminish mortality [2]

Specific

monomorphic ventricular tachycardia non-sustained ventricular tachycardia polymorphic ventricular tachycardia sustained ventricular tachycardia ventricular fibrillation (V Fib) ventricular flutter

General

ventricular arrhythmia wide complex tachycardia

Figures/Diagrams

Figures/diagrams/slides/tables related to ventricular tachycardia (VT)

References

  1. Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 147-48
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 19 American College of Physicians, Philadelphia 1998, 2006, 2009, 2022. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. American Heart Association
  4. Marill KA et al, Amiodarone is poorly effective for the acute termination of ventricular tachycardia Ann Emerg Med 2006; 47:217 PMID: 16492484 - Tomlinson DR et al, Intravenous amiodarone for the pharmacological termination of haemodynamically-tolerated sustained ventricular tachycardia: Is bolus dose amiodarone an appropriate first-line treatment? Emerg Med J 2008, 25:15 PMID: 18156531
  5. Cuculich PS, Schill MR, Kashani R. Noninvasive Cardiac Radiation for Ablation of Ventricular Tachycardia. N Engl J Med 2017; 377:2325-2336. December 14, 2017 PMID: 29236642 http://www.nejm.org/doi/full/10.1056/NEJMoa1613773 - John RM, Stevenson WG Noninvasive Ablation of Ventricular Tachycardia. N Engl J Med 2017; 377:2388-2390. December 14, 2017 PMID: 29236632 http://www.nejm.org/doi/full/10.1056/NEJMe1713245
  6. Al-Khatib SM 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 Oct 30 PMID: 29084731 http://circ.ahajournals.org/content/early/2017/10/30/CIR.0000000000000549
  7. Robinson CG et al. Phase I/II trial of electrophysiology-guided noninvasive cardiac radioablation for ventricular tachycardia. Circulation 2018 Nov 10; Not indexed in PubMed https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.118.038261 - Zei PC, Mak R. Noninvasive stereotactic radioablation for ventricular tachycardia: ENCORE-VT (EP-guided noninvasive cardiac radioablation): Is the sequel as good as the original? Circulation 2018 Nov 10; Not indexed in PubMed https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.118.038285