Makindo Medical Notes

Related Subjects: |Classical Ventricular Tachycardia |Idiopathic Ventricular Tachycardia |Right Ventricular Outflow Tract Tachycardia |Idiopathic Fascicular Left Ventricular Tachycardia |Left Ventricular Outflow Tract Tachycardia |Ventricular Fibrillation |Resuscitation - Adult Tachycardia Algorithm |Resuscitation - Advanced Life Support |Automatic Implantable Cardioverter Defibrillator (AICD)

⚡ Idiopathic ventricular tachycardia (IVT) in patients with an anatomically normal heart is a distinct entity. Its management and prognosis differ from VT associated with structural heart disease. 👉 RVOT VT is the commonest form of idiopathic VT, and should always be distinguished from ARVC/ARVD.

📖 About

• A form of Idiopathic Ventricular Tachycardia (IVT).
• ~80% of IVT cases arise from the Right Ventricular Outflow Tract (RVOT). 🫀
• ECG: Typically shows LBBB morphology because the arrhythmia originates in the RV. 📉

🧬 Aetiology & Mechanism

• Occurs in the absence of structural heart disease ✅.
• Usually due to a re-entrant or triggered activity mechanism involving the RVOT.
• Classically non-sustained, repetitive, and monomorphic VT.
• Triggered by exercise, stress, or catecholamine surges (adrenergic-dependent). 🏃‍♀️💉

✅ Diagnostic Criteria

• No structural heart disease (confirmed by Echo/CMR).
• No metabolic or electrolyte abnormalities (exclude hypokalaemia, hypomagnesaemia, thyroid). 🔬
• No inherited channelopathy (e.g., Long QT, Brugada, CPVT).

📊 RVOT VT ECG Example

👩‍⚕️ Clinical Features

• Commoner in females, typically aged 30–50 years 👩.
• Paroxysmal, exercise-induced sustained VT episodes. 🏋️‍♀️
• Symptoms: Palpitations 💓, presyncope/syncope 😵, occasional chest tightness.
• Often well tolerated but recurrent → lifestyle impairment.

🧪 Investigations

• 🧾 Bloods, Echo, CXR: Normal.
• 📉 ECG during VT: LBBB morphology + inferior axis (due to RVOT origin). → rS in V1 and tall R in V6 are typical. 👉 Key exam pearl: ARVD/ARVC differs — resting ECG often shows T-wave inversion in V1–V3 ± epsilon wave.
• 🏃‍♀️ Exercise stress test: May provoke VT (adrenergic trigger).
• 🧲 MRI: Can show subtle RV wall abnormalities in up to 70% (but be cautious — overlaps with ARVD).

🚨 Classical VT is still the most common cause of wide-complex tachycardia. There is no completely reliable way to distinguish classical VT from idiopathic VT or SVT with aberrancy by surface ECG alone. 👉 Always treat as VT until proven otherwise.

💊 Management

• 🔑 First rule: If diagnosis not certain ➝ treat as classical VT per ALS Adult Tachycardia algorithm.
• ABC + early Echo to confirm LV function.
• 🏥 If stable RVOT VT confirmed ➝ may terminate with Adenosine 6–24 mg (diagnostic & therapeutic). ❗ Not effective in ARVD.
• Verapamil IV (10 mg over 3–5 min) can be effective, but only if Echo confirms normal LV function. ⚡ Be prepared for DC cardioversion if patient deteriorates.
• Beta-blockers (especially non-selective) may suppress adrenergic-triggered VT.
• 💡 Radiofrequency ablation (RF ablation) offers curative treatment with >85–90% success rates for recurrent symptomatic RVOT VT.

📚 References

• ESC – How to recognise and manage idiopathic ventricular tachycardia