Primary Electrical Cardiac Diseases: A Clinician’s Overview of Mechanisms & Management
Primary electrical cardiac diseases—often called channelopathies or primary arrhythmic disorders—are conditions where the heart’s electrical system is abnormal despite a structurally normal heart. These disorders can cause palpitations, syncope, seizures, or sudden cardiac death, especially in young individuals with otherwise normal echocardiograms.
Below is a simple, practical guide to the major primary electrical cardiac diseases and their management.
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1. Long QT Syndrome (LQTS)
A genetic disorder of delayed myocardial repolarization, leading to prolonged QT interval and risk of torsades de pointes.
Red Flags
Syncope with emotion, exertion, or swimming
Family history of sudden death
QTc ≥ 480–500 ms on ECG
Management
Ξ²-blockers (Nadolol or Propranolol preferred)
Avoid QT-prolonging medications
ICD for high-risk or survivors of cardiac arrest
Left cardiac sympathetic denervation (LCSD) in refractory cases
Genetic screening of family members
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2. Short QT Syndrome (SQTS)
Opposite of LQTS: QTc ≤ 330–360 ms, causing high atrial and ventricular arrhythmic risk.
Management
ICD is the mainstay
Quinidine may be used as adjunct therapy to prolong QT
Screening of first-degree relatives
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3. Brugada Syndrome
A sodium-channel disorder causing coved ST elevation in V1–V3 and high risk of VF, especially in sleep.
Triggers
Fever
Large meals/alcohol
Sodium-blocking drugs
Management
Aggressive fever control
Avoid contraindicated drugs
ICD for symptomatic patients or spontaneous type-1 ECG with syncope
Quinidine for arrhythmia suppression in selected cases
Epicardial ablation of RVOT substrate in recurrent VF (“Brugada storm”)
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4. Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)
Normal resting ECG; exercise or emotional stress triggers bidirectional or polymorphic VT.
Management
Ξ²-blockers without intrinsic sympathomimetic activity (Nadolol)
Flecainide added if breakthrough arrhythmias
Avoid strenuous/emotional triggers
ICD only if arrhythmias persist despite optimal therapy
Family screening essential
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5. Wolff–Parkinson–White (WPW) Syndrome
Presence of an accessory pathway causing pre-excitation and potential for AVRT or rapid AF transmission.
ECG Features
Short PR
Delta wave
Wide QRS
Management
Catheter ablation is curative and first-line in symptomatic or high-risk pathways
Avoid AV nodal blockers in AF with pre-excitation
Emergency management of pre-excited AF: Procainamide or DC shock
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6. Early Repolarization Syndrome (Malignant ER Pattern)
Traditionally benign, but certain patterns (inferolateral J waves with ST elevation) increase VF risk.
Management
ICD for survivors of VF
Isoproterenol for acute VF storms
Quinidine may reduce recurrence
Lifestyle: avoid triggers; correct electrolytes
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7. Sick Sinus Syndrome (Inherited Forms)
Rare genetic dysfunction of the sinus node causing bradycardia, pauses, chronotropic incompetence.
Management
Permanent pacemaker if symptomatic
Evaluate for associated channelopathies
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Practical Workup in Suspected Electrical Heart Disease
1. ECG + high-lead V1–V3 placement
2. Holter monitoring / event recorder
3. Exercise test (useful in CPVT, LQTS)
4. Drug challenge (Ajmaline for Brugada, epinephrine for LQTS—specialist only)
5. Electrophysiology study for selected patients
6. Genetic testing when suspicion is high
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When to Suspect a Primary Electrical Disease
Syncope with normal echo
Seizures misdiagnosed as epilepsy
Family history of sudden death < 40 years
No structural heart disease but recurrent arrhythmias
Event triggered by emotion, sleep, fever or exercise
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Take-Home Messages
These diseases kill young people with structurally normal hearts—high suspicion saves lives.
ECG patterns + clinical triggers are key.
Ξ²-blockers, quinidine, ICDs, and ablation form the backbone of therapy, depending on the condition.
Family screening is crucial due to strong genetic links.
Thanks
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