Paroxysmal Tachycardia

Paroxysmal Tachycardia

1. Definition
   Paroxysmal tachycardia (also called paroxysmal supraventricular tachycardia) is a sudden, brief episode of rapid heart rate that starts and stops abruptly and originates above the ventricles.

2. Causes / Etiology

• Often occurs in otherwise healthy young people.
• Stress, anxiety, excitement or sudden fright can precipitate an attack.
• Stimulants such as caffeine, nicotine, alcohol or certain drugs (e.g., decongestants).
• Underlying heart disease – coronary artery disease, heart failure, valvular lesions or congenital conduction abnormalities.

3. Types or Classification
   Atrioventricular nodal re‑entrant tachycardia (AVNRT) – the most common; a re‑entry circuit within the AV node.
   Atrioventricular re‑entrant tachycardia (AVRT) – uses an accessory pathway (e.g., Wolff‑Parkinson‑White) to form a loop.
   Focal atrial tachycardia – a single ectopic focus in the atrial muscle fires rapidly.

4. Pathology (stepwise)
   AVNRT:
   step 1 → an impulse enters the AV node from the atria,
   step 2 → it travels down the slow pathway,
   step 3 → then returns up the fast pathway, creating a rapid circular circuit.

AVRT:
step 1 → impulse travels normally down the AV node to the ventricles,
step 2 → it re‑enters the atria through an accessory (bypass) tract,
step 3 → the circuit repeats, producing a very fast rate.

Focal atrial tachycardia:
step 1 → an abnormal atrial cell becomes automatic,
step 2 → it fires impulses faster than the sinus node,
step 3 → the rapid impulses dominate the rhythm.

5. Clinical Features
   General – palpitations, feeling of “fluttering” in the chest, shortness of breath, chest discomfort, dizziness, fatigue, sweating.
   Specific – sudden onset of a regular rapid pulse (often >150 beats/min), may be associated with anxiety or a sense of impending doom; episodes last from a few seconds to several hours and stop abruptly.

6. Complications
   Acute – transient drop in cardiac output, hypotension, syncope, possible progression to ventricular tachycardia or fibrillation.
   Chronic – repeated episodes can lead to tachy‑cardia‑induced cardiomyopathy, reduced exercise tolerance and impaired quality of life.

7. Diagnosis / Investigations
   Routine – 12‑lead ECG (shows narrow‑complex tachycardia, regular rhythm); blood glucose, electrolytes, thyroid profile to exclude metabolic triggers.
   Special – Holter or event monitor for intermittent episodes; electrophysiological study (EPS) to locate the re‑entry circuit and guide ablation; echocardiogram to assess structural heart disease.

8. Management
   General measures – vagal maneuvers (bearing down, cold water face immersion, carotid sinus massage) to break the circuit.
   Acute drug therapy – rapid IV adenosine (0.5 mg then 1 mg if needed) to terminate AVNRT/AVRT; beta‑blockers or calcium‑channel blockers if adenosine contraindicated.
   Modern treatment – catheter radio‑frequency ablation of the re‑entry pathway (high cure rate, preferred for recurrent cases).
   Dietary advice – limit caffeine, energy drinks, alcohol; maintain regular meals, avoid heavy meals before sleep; ensure adequate hydration and balanced electrolytes.

9. Homeopathic Therapeutics (key remedies)

Aconitum napellus

• Sudden onset of rapid pulse after fright or shock.
• Marked anxiety, fear of death.
• Palpitations with a sense of suffocation.
• Throbbing headache, restlessness.
• Cold, clammy skin.
• Symptoms improve in open air.

Digitalis purpurea

• Slow, irregular pulse with occasional rapid bursts.
• Weakness, fatigue, breathlessness on exertion.
• Palpitations that feel “skipping”.
• Visual disturbances (yellow halos).
• Better after warm drinks.
• History of heart failure.

Kali mur. (Kali muriaticum)

• Palpitations with nervousness and trembling.
• Fear of losing control, irritability.
• Episodes triggered by emotional upset.
• Dry mouth, thirst for cold water.
• Better in open air, worse in warm rooms.
• Restlessness at night.

Natrum muriaticum

• Tachycardia after grief, emotional loss.
• Palpitations with a feeling of “tightness” in chest.
• Aversion to salty foods, craving for sweets.
• Headache, insomnia.
• Symptoms improve in cool, fresh air.
• Tendency to be introverted, solitary.

Phosphorus

• Rapid, irregular pulse with anxiety and fear of death.
• Palpitations worsen at night, especially after lying down.
• Burning sensation in chest, thirst for cold drinks.
• Restlessness, desire for fresh air.
• Sensitive to noise, light, and cold drafts.
• Better after taking a warm drink.