Makindo Medical Notes.com

Related Subjects: |Ventricular Fibrillation |Classical Ventricular Tachycardia |Idiopathic Ventricular Tachycardia |Resuscitation - Adult Tachycardia Algorithm |Resuscitation - Advanced Life Support |Automatic Implantable Cardioverter Defibrillator (AICD) |Brugada Syndrome |Long QT syndrome (LQTS) Acquired |Long QT syndrome (LQTS) Congenital |Torsades de Pointes |Wolff-Parkinson White syndrome (WPW) |Supraventricular Tachycardia (SVT) |Atrial Flutter |Atrial Fibrillation

Ensure that you have a defibrillator close by and switched on and you know how to use it. Follow Adult tachycardia algorithm as linked above.

About

• More than 3 beats regular broad complex tachycardia rate > 120/min.
• Commonest cause is Ischaemic Heart Disease.
• Some patients may appear stable but can quickly decompensate so all must be treated as having the potential to cardiac arrest.
• Admit CCU. Instant access to defibrillation is vital in all cases

Types

• Sustained VT: lasts more than 30 seconds
• Non-Sustained VT: It is defined as 3 (sometimes 5) or more consecutive beats arising below the AVN with an RR interval of <600 ms (>100 beats/min) and lasting <30s

Causes

• Ischaemic cardiomyopathy
• LVH e.g. Hypertension
• Idiopathic dilated cardiomyopathy
• Brugada syndrome
• Arrhythmogenic right ventricular cardiomyopathy
• Myocarditis
• Cardiomyopathy e.g. HCM, DCM
• Overdose: Tricyclic overdose, Digoxin, antiarrhythmics
• Hypo/hyperkalaemia, Hypomagnesaemia
• Cocaine, Phaeochromocytoma
• Cong/Acquired Long QT syndromes
• RVOT Ventricular tachycardia with LBBB and RAD

Clinical

• Broad spectrum from mild symptoms and palpitation to cardiac arrest.
• Pulmonary oedema, Hypotension, Syncope, Presyncope
• Chest pain, Dizziness,
• Cannon a" wave in JVP, Depends on rate and LV function

Rhythm Strips ECG Ventricular Tachycardia

12 lead Ventricular Tachycardia

VT more likely if

• Fusion beats, Capture (narrow) beats, IHD, structural heart disease
• No RS wave on chest leads, AV dissociation
• RBBB > 0.14 secs LBBB > 0.16 secs, Extreme LAD, Extreme R to R regularity

Differential Regular wide rhythm >120/min

• Ventricular tachycardia,
• Atrial flutter with BBB (150/min)
• SVT with BBB (BBB: bundle branch block)
• Severe hyperkalaemia
• Pre-excited Atrial tachycardia

Investigations

• Check FBC, U&E, Mg, Ca, Lactate, ABG if needed.
• Urgent ECG: wide QRS > 3 small squares, regular.
• Troponin, BNP levels, Echocardiogram.
• Coronary Angiography and PCI if chest pain and ? STEMI

Classical VT is by far the most common cause of wide complex regular tachycardia, and there is no perfectly reliable way to distinguish classic VT with all its dangers from idiopathic VT or SVT with aberrancy on the surface 12-lead ECG. Treat as Classical VT - follow Adult tachycardia algorithm above

Acute Management

• ABC. If pulseless then CPR +DC shock. O₂ as per guidelines. IV 500 mls with 20 mmol KCl to keep potassium > 4.5 mmol/l + oral supplements. Revascularisation if STEMI or severe ischaemic basis suspected
• Stable: urgent 12 lead ECG, IV access. Bloods. Monitor. Be ready to give a DC shock.
• Pharmacological choices if stable
  • IV Metoprolol 5 mg
  • IV Amiodarone 300 mg over 30 mins and then 900 mg over 24hrs through central line.
  • IV Lidocaine 50 mg over 2 minutes. Can be repeated every 5 minutes to a max 200 mg
  • IV Magnesium Sulphate 2 g (8 mmol) over 15 mins
• Unstable/ Pulseless: ABC, DC countershock. Bloods. Consider IV Amiodarone.
• ACS/STEMI then treat/PCI. Look for and treat cause. Correct electrolytes.
• Long term
  • Non sustained VT: Consider Beta blockers. Where LV function (EF<30%) is poor consider for AICD
  • Long term: Chronic prophylactic antiarrhythmic drug therapy. Investigating cause Echo, possibly Angiography and Electrophysiological studies, Holter monitoring.
  • AICD: Those who survive the first episode of life-threatening ventricular arrhythmia are at high risk of further episodes and an ICD should be considered.
  • Catheter Ablation may be considered

References