see also: [[Torsades de Pointes|TdP]], [[Wide complex tachycardia]], [[ECG artifact]], [[APLS#paeds VT]], [[Anti-arrhythmic drugs]] - [Mattu - approach to wide complex tachycardia](x-devonthink-item://371DA077-95EB-4C7C-85F6-E8D9026BFEE3?page=163) - [Bear Ventricular tachycardia](bear://x-callback-url/open-note?id=278A70BC-F813-4F31-98A3-21C7C3B516B4-59382-00011505F1306FF9) - [Dunn - Ventricular arrhythmias](x-devonthink-item://747079B5-0629-433D-A6A2-5282259F31B6) - [Braunwald - VT in IHD -- ECG location of VT](x-devonthink-item://18E3C9C6-F903-460A-9B39-E4A2B50B5AA6?page=20) ![[Pasted image 20230610182629.png]] Flow diagram for distinguishing ventricular tachycardia from SVT with aberrancy. Top ECG panels show **AV dissociation** (arrows) with a **fusion beat** (f) and **capture beat** (C). source: [Braunwald - wide complex tachycardia](x-devonthink-item://38A3BEDB-C02F-44C2-B5DE-0CC33DDE6909?page=11) # Differentiation between VT and SVT > [!quote] > Despite multiple attempts by researchers and clinicians, no elements of the patient's history, clinical characteristics, or ECG algorithm have been demonstrated to have acceptable precision in determining the cause of WCT... *It is perfectly acceptable for an emergency physician to provide a final interpretation of the abnormal ECG with WCT as "wide complex tachycardia of uncertain (undetermined) etiology."* In fact, not establishing a definitive diagnosis might result in better patient care and outcomes, as the focus of care is directed towards the patient's clinical condition and hemodynamic status, not the correct ECG interpretation... *A regular WCT should be managed as VT... an irregular WCT suggests a supraventricular source such as AF with an accessory pathway* -- [Amal Mattu](x-devonthink-item://371DA077-95EB-4C7C-85F6-E8D9026BFEE3?page=173&annotation=Highlight&x=55&y=639) - AV dissociation - regular R-R interval - Northwest axis (-90 deg negative or more positive than +180deg) - RBBB and duration > 140 ms or LBBB and duration > 160 ms - precordial concordance -- main direction of QRS complexes is teh same in all precordial leads. - positive precordial QRS concordance can occur during VT or SVT. - negative precordial concordance is predictive of VT - neither fusion nor capture beats are diagnostic for VT despite suggestions from older literature, but they do favor VT as mechanism for WCT **Features that suggest VT:** - Very broad complexes (>160ms) - Absence of typical RBBB or LBBB morphology - Extreme axis deviation (“northwest axis”) - AV dissociation (P and QRS complexes at different rates) - **Capture beats** — occur when the sinoatrial node transiently ‘captures’ the ventricles, in the midst of AV dissociation, to produce a QRS complex of normal duration - **Fusion beats** — occur when a sinus and ventricular beat coincide to produce a hybrid complex of intermediate morphology - Positive or negative **precordial concordance** throughout the chest leads, i.e. leads V1-6 show entirely positive (R) or entirely negative (QS) complexes, with no RS complexes seen - this is *different* from concordance in evaluating LBBB for sgarbossa! here, this simply means that all the precordial leads are concordant with one another. - Josephson’s sign – Notching near the nadir of the S-wave - Brugada’s sign – The distance from the onset of the QRS complex to the nadir of the S-wave is > 100ms - RSR’ complexes with a taller “left rabbit ear”. This is the most specific finding in favour of VT. This is in contrast to RBBB, where the right rabbit ear is taller ![[Pasted image 20240901011745.png]] # Ventricular causes of wide complex tachycardia - accelerated idiopathic ventricular rhythm - monomorphic VT - paced rhythm (including pacemakiner-mediated tachycardia) - polymorphic VT - bidirectional VT - multifocal VT - torsades de pointes ## polymorphic VT > Besides [[Torsades de Pointes|torsades]], polymorphic VT caused by [delayed afterdepolarisations](x-devonthink-item://A45FDA08-6B2C-446C-8756-C67F9F1A45BD?page=9) (DAD). **unlike** TdP, polymorphic VT from DADs are more likely to occur with fast spontaneous or paced rates or with increased premature beats. - [[ACS]] (most common) - mechanism: ↑ intracellular Ca in ischaemic myocardium → ↑ delayed afterdepolarisations - re-perfusion injury - [[Syncope ECG patterns|Brugada]] and other inherited channelopathies - [[Digoxin toxicity]] - mechanism: Na/K pump inhibited → accumulation of intracellular Na+ → enhancement of Na/Ca exchange in reverse mode (3 Na out for 1 Ca in) → accumulation of intracellular Ca - catacholamines - Can be torsades / due to long QT (if QT not known first) - Misc besides defibrilation, *lignocaine* may help treat this. # Torsades de pointes Torsades de pointes is a ventricular tachycardia. In the unstable patient, **cardiovert**. In the pulseless, **defibrillate**. (The polymorphic nature of the rhythm may interfere with the defibrillator’s ability to synchronize, so cardioversion may not be possible. In that case, in the unstable patient, deliver an unsynchronized shock.) **Speed up the heart** to decrease the QT interval - isoproterenol 5mcg/min titrate to 30 beats/min above patients natural rate DO NOT give amiodarone or procainamide. **lignocaine** 1.5 mg/kg load can be considered ## Magnesium - loading dose of 2g IV (or 10mmol, which is 2.4g), repeat once if no clinical effect . give over 10-20 minutes, or slow push if unstable patient - start infusion at 1-4 g/h - monitor mag levels; if >2.5 cut infusion in half, >3 stop infusion > The major side effect of hypermagnesemia is depression neuromuscular function. Monitor reflexes, bradycardia, respiratory distress. Be prepared to intubate --- # Examples ![[Pasted image 20240901012140.png|monomorphic VT with northwest axis]] ![[Pasted image 20250302012126.png|note the negative concordance of precordial leads]] ![[Pasted image 20240901012236.png|WCT due to AF with RBBB and LAFB. identical QRS complexes on prior ECG]] ![[Pasted image 20240901012319.png|WCT with AF and LBBB; tachycardia due to sepsis]] ![[Pasted image 20240901012344.png|AF with WPW. chotic wide complex tachy is irregular. delta waves seen in V4-V6]] ![[Pasted image 20240901012431.png|monomorphic VT with RBBB and left superior axis (NW axis). confirmed with EP reentry loop in LV apex. verapamil responsive, but generally do NOT give calcium channel blockers for WCT in ED!]] ![[Pasted image 20240901012550.png|VT with capture beats (QRS complexes 6, 10, and 17)]] ![[Pasted image 20240901012650.png|VT demonstrating AV dissociation seen in lead II strip. Capture (QRS #19) and fusion (QRS #11, 15, 20) complexes]] ![[Pasted image 20240901012827.png| positive precordial concordance, but this ECG is 2:1 flutter and RBBB]] ![[Pasted image 20240901013031.png|VT. AV dissociation seen esp V1 and II.]] ![[Pasted image 20240901013142.png| SVT and RBBB. prior ECG showed pre-existing RBBB and identical QRS morphologies]] ![[Pasted image 20240901013329.png|VT rate 155. very wide 0.176 seconds. caused by hyper-K (8.1). Tx calcium]] # Related Questions ## torsades - [ ] DUPLICATE Q: [Syncope](x-devonthink-item://9C485EF0-3985-4EBA-B9DC-9CDF8A6E2F45?page=7) -- [Answer](x-devonthink-item://A0D348CE-FCD4-4ECD-BE21-6CA73F6DE8CD?page=11) ## torsades de pointes - [ ] DUPLICATE Q: [Dizziness and Abnormal ECG](x-devonthink-item://27CD16C2-557A-4CB1-B3CF-D01330708170?page=13) -- [Answer](x-devonthink-item://00427DF6-6D28-4FEB-A0CA-DF96DBBBCE97?page=17) - [ ] DUPLICATE Q: [Collapse with Abnormal Rhythm Strip](x-devonthink-item://73409C77-B2FA-4E0A-AEB3-5EB284457F0C?page=46) -- [Answer](x-devonthink-item://5A848952-80E3-4184-B553-368412A69917?page=31) - [ ] DUPLICATE Q: [ECG for Lightheadedness](x-devonthink-item://CDB16617-3785-40E5-B8BE-5668D2D7A3E7?page=6) -- [Answer](x-devonthink-item://A6CA01E8-9551-45E7-8617-441BE3DBB5D7?page=5) ## ventricular tachycardia - [ ] 71Q: [VT](x-devonthink-item://2CB6E202-E7C1-46E8-B49F-435AB6C937F0?page=16) -- [Answer](x-devonthink-item://78503782-404C-41A2-A3AE-B1A26F578DF5?page=19) -- [prop](x-devonthink-item://51B63B5B-D684-4BF3-8B62-95FCA5EF7503?page=7) - [ ] DUPLICATE Q: [Arrhythmia](x-devonthink-item://5DC0999B-D537-4002-86AF-FD7B54B45E2E?page=1) -- [Answer](x-devonthink-item://406AF611-5CD4-4B3B-9795-327E8F4E3626?page=0) - [ ] 72Q: [Ventricular Tachycardia](x-devonthink-item://834C484F-DDAA-4819-8DF0-84AE5E70DA1D?page=53) -- [Answer](x-devonthink-item://D46998FE-62E2-4A3A-860D-C32C94B86E42?page=23) - [ ] DUPLICATE Q: [Abnormal ECG](x-devonthink-item://FE3157C2-07B3-43F2-9ECE-AFACE1355E13?page=26) -- [Answer](x-devonthink-item://DDC959EB-0C1E-448A-8380-C397BF734322?page=12) - [ ] DUPLICATE Q: [Broad Complex Tachycardia](x-devonthink-item://A8F2D7A0-9A26-4012-AF42-19D640D674B4?page=18) -- [Answer](x-devonthink-item://A10DE51E-92FA-42D1-8AA0-7AE68C2FA743?page=9) - [ ] DUPLICATE Q: [Arrhythmia and Chest Pain](x-devonthink-item://09CFA1A7-00F1-4151-979E-8F3984924D54?page=17) -- [Answer](x-devonthink-item://CF5E9C2B-42F9-4F9C-AC29-877E20134927?page=11) - [ ] 73Q: [Ventricular Tachycardia](x-devonthink-item://7E9EF652-F67B-42C5-A536-2EE85BA1954F?page=12) -- [Answer](x-devonthink-item://2DE5FACA-6D8F-41A2-8EAA-8DFE1E76FA61?page=7) ## vt - [x] DUPLICATE Q: [VT](x-devonthink-item://2CB6E202-E7C1-46E8-B49F-435AB6C937F0?page=16) -- [Answer](x-devonthink-item://78503782-404C-41A2-A3AE-B1A26F578DF5?page=19) - [x] DUPLICATE Q: [Arrhythmia](x-devonthink-item://5DC0999B-D537-4002-86AF-FD7B54B45E2E?page=1) -- [Answer](x-devonthink-item://406AF611-5CD4-4B3B-9795-327E8F4E3626?page=0) - [x] DUPLICATE Q: [Ventricular Tachycardia](x-devonthink-item://834C484F-DDAA-4819-8DF0-84AE5E70DA1D?page=53) -- [Answer](x-devonthink-item://D46998FE-62E2-4A3A-860D-C32C94B86E42?page=23) - [x] DUPLICATE Q: [Abnormal ECG](x-devonthink-item://FE3157C2-07B3-43F2-9ECE-AFACE1355E13?page=26) -- [Answer](x-devonthink-item://DDC959EB-0C1E-448A-8380-C397BF734322?page=12) - [x] DUPLICATE Q: [Broad Complex Tachycardia](x-devonthink-item://A8F2D7A0-9A26-4012-AF42-19D640D674B4?page=18) -- [Answer](x-devonthink-item://A10DE51E-92FA-42D1-8AA0-7AE68C2FA743?page=9) - [x] DUPLICATE Q: [Arrhythmia and Chest Pain](x-devonthink-item://09CFA1A7-00F1-4151-979E-8F3984924D54?page=17) -- [Answer](x-devonthink-item://CF5E9C2B-42F9-4F9C-AC29-877E20134927?page=11) - [x] DUPLICATE Q: [Ventricular Tachycardia](x-devonthink-item://7E9EF652-F67B-42C5-A536-2EE85BA1954F?page=12) -- [Answer](x-devonthink-item://2DE5FACA-6D8F-41A2-8EAA-8DFE1E76FA61?page=7)