Tachycardia: Ventricular Arrhythmia

Premature Ventricular Contractions (PVCs)

• Occur in 75% of healthy individuals
• Pts report sensation of skipped beat or extra strong beat
• If no syncope, no structural heart disease or no FHx of sudden cardiac death then reassure!
• More common in HTN, LVH, HF, myocardial ischaemia, IHD. Rx with Beta blocker or Ca channel blocker, and Catheter ablation in those who fail medical Rx.

Ventricular Tachycardia with Structural Heart disease

• Rhythm greater than 100 BPM
• Originates in the ventricles
• Sustained if is lasts >30 secs or produces haemodynamic collapse
• Pts with previous MI or CM, VT usually monomorphic originating from small pathways of viable myocardium within scarred tissue
• SCD more common in those with poor EF, rapid VT, hypotension and syncope
• Rx: Beta blocker

In those with VF, haemodynamic unstable VT, or stable VT with structural heart disease ICDs are indicated. Amiodarone and Sotalol used as anti-arrhythmics to reduce ICD shock but do not reduce mortality. Catheter ablation for those with recurrent VT.

Idiopathic VT

• Usually provoked by exercise or emotional stress
• occurs more frequently in women than men in ages 20-40s
• Monomorphic and usually originates from RV outflow tract.
• ECG: runs of VT with LBBB pattern that is positive in inferior leads
• Differential: Arrhythmogenic right ventricular cardiomyopathy / Dysplasia (ARVC/D) which has epsilon waves 
• Treadmill test performed to see if provokes VT, and to look for ischaemia
• Echocardiogram done to look for structural abnormality
• Rx: Ca channel blockers, Beta blockers, class I or III antiarrhythmics, catheter ablation ( in order of preference)
• ICD NOT indicated

Ventricular Fibrillation (VF)

• Often the cause of sudden cardiac death
• Preceded by VT or ischaemic event usually
• ALS algorithm indicated and it is a SHOCKABLE rhythm
• Require ICD in the aftermath as part of secondary prevention