A disturbance in the electrical activity of the heart leading to abnormal heart rates (too fast or too slow) and irregular rhythms.
Types:
- Bradycardia
→ Slow heart rate (<60 bpm)
- Tachycardia
→ Fast heart rate (>100 bpm)
- Arrhythmias
→ Irregular heartbeats
- Conduction Disorders
→ Heart block, accessory pathways
1. BRADYCARDIA
(Slow Heart Rate <60 bpm)
• Causes:
- Sick Sinus Syndrome
(SA Node Dysfunction)
- AV Block (First, Second, Third Degree)
- Hypothyroidism, Hypothermia
- Drugs: Beta-Blockers, Digoxin
Mnemonic:
"SLOW" (Causes of Bradycardia)
- Sick Sinus
Syndrome
- Low
Temperature (Hypothermia)
- Overdose of
Drugs (Beta-Blockers, Digoxin)
- Weak SA or
AV Node (AV Block)
Treatment: Atropine, Pacemaker (if severe)
2. TACHYCARDIA
(Fast Heart Rate >100 bpm)
• Causes:
- Sinus Tachycardia
(Exercise, Fever, Stress, Anemia, Hyperthyroidism)
- Supraventricular Tachycardia (SVT)
→ Re-entry Circuit in Atria
- Atrial Fibrillation (AF)
→ Irregularly Irregular Pulse
- Ventricular Tachycardia (VT)
→ Dangerous, can lead to Cardiac Arrest
Mnemonic:
"FAST" (Causes of Tachycardia)
- Fever, Fear
(Anxiety)
- Anemia,
Arrhythmias
- Stress,
Stimulants (Caffeine, Smoking)
- Thyroid
(Hyperthyroidism)
Treatment:
- Sinus Tachycardia
→ Treat underlying cause (Fever, Anemia, Anxiety)
- SVT → Valsalva
Maneuver, Adenosine, Beta-Blockers
- Atrial Fibrillation
→ Rate control (Beta-Blockers, Digoxin), Anticoagulants
- Ventricular Tachycardia
→ Emergency Shock (DC Cardioversion, Amiodarone)
3. ARRHYTHMIAS
(Irregular Heartbeats)
Types:
1. Supraventricular Arrhythmias (Above Ventricles)
- Atrial Fibrillation (AF)
→ Irregular pulse, No P waves on ECG
- Atrial Flutter
→ "Saw-tooth" ECG waves
- AVNRT (AV Nodal Re-entrant
Tachycardia) → Sudden Fast Heart Rate
2. Ventricular Arrhythmias (Dangerous!)
- Ventricular Tachycardia (VT)
→ Wide QRS, Can Lead to Cardiac Arrest
- Ventricular Fibrillation (VF)
→ Irregular, Deadly, Needs Defibrillation
Mnemonic:
"AF-FLUTTER-VT-VF" (Types of Arrhythmias)
- Atrial Fibrillation
(Irregular Pulse)
- Atrial Flutter
(Saw-tooth ECG)
- Ventricular Tachycardia (VT)
(Fast, Wide QRS)
- Ventricular Fibrillation (VF)
(Irregular, Fatal)
Treatment:
- AF & Flutter
→ Rate Control (Beta-Blockers, Digoxin), Anticoagulants
- VT & VF
→ Defibrillation (Shock), Amiodarone, CPR
4. CONDUCTION
DISORDERS (HEART BLOCKS)
Types:
- First-Degree AV Block → PR interval prolonged (>0.2 sec), No dropped beats
- Second-Degree AV Block
- Type 1 (Mobitz I)
→ PR Interval progressively increases, then drops a beat
- Type 2 (Mobitz II)
→ Sudden drop of QRS (More Dangerous!)
3️⃣ Third-Degree (Complete) Heart Block → Atria & Ventricles beat independently, Needs Pacemaker!
Mnemonic:
"1-2-3 = Slow-Sudden-Stop" (Heart Blocks)
- 1st Degree
→ Slow Conduction (Prolonged PR Interval)
- 2nd Degree
→ Sudden Drop of QRS
- 3rd Degree
→ Complete Stop (No Connection Between Atria & Ventricles)
Treatment:
- First-Degree
→ No Treatment Needed
- Second-Degree
→ Pacemaker (If Symptomatic)
- Third-Degree
→ Permanent Pacemaker!
DIAGNOSIS OF
HEART RHYTHM DISORDERS
ECG (Electrocardiogram) → Gold Standard!
Holter Monitor → 24-hour ECG for Arrhythmias
Electrophysiology Study (EPS) → To identify abnormal
circuits
Blood Tests → Thyroid, Electrolytes (K+, Mg2+), Troponin (Heart
Attack)
Mnemonic:
"ECHO-H" (Tests for Arrhythmias)
- ECG → Check
Rhythm
- Cholter
Monitor → 24-hour ECG
- Holter →
Long-Term Monitoring
- Other Blood
Tests (Thyroid, Electrolytes)
- Heart Study
(EPS for Arrhythmias)
TREATMENT OF
HEART RHYTHM DISORDERS
1. Bradycardia
Treatment
Atropine (Increases Heart Rate)
Pacemaker (For Persistent Cases)
2. Tachycardia
Treatment
Sinus Tachycardia → Treat Cause (Fever, Anemia, Anxiety)
SVT → Valsalva, Adenosine, Beta-Blockers
AF → Beta-Blockers, Digoxin, Anticoagulants (Warfarin, DOACs)
VT & VF → Shock (Defibrillation, CPR, Amiodarone)
3. Heart Block Treatment
First Degree → No Treatment Needed
Second Degree (Mobitz II) → Pacemaker
Third Degree (Complete Block) → Permanent
Pacemaker!
Mnemonic:
"P-A-C-E" (Treatment for Arrhythmias)
- Pacemaker
(Bradycardia, Heart Blocks)
- Adenosine
(SVT)
- Cardioversion
(AF, VT)
- Epinephrine
& CPR (VF)
FINAL REVISION WITH MNEMONICS
- Bradycardia = "SLOW" (Sinus Problem, Low Temp, Overdose, Weak Node)
- Tachycardia = "FAST" (Fever, Anemia, Stress, Thyroid)
- Arrhythmias = "AF-FLUTTER-VT-VF"
- Heart Blocks = "1-2-3 = Slow-Sudden-Stop"
- Diagnosis = "ECHO-H" (ECG, Holter, EPS, Blood Tests)
- Treatment = "P-A-C-E" (Pacemaker, Adenosine, Cardioversion, Epinephrine)
