Arrythmias

Question 1

What are the two sources of bradycardia?

Answer 1

1. Impulse Generation issues
   - Sinus Bradycardia (High Vagal Tone [athletes, young], Sick sinus Syndrome, Drugs [beta blocker, calcium channel blocker], Injury to SA node [ischemia or infection], hypothyroidism
   - Asystole
2. Interrupted Conduction from Atrium to Ventricle (Heart Block)
   - 1st degree (prolonged duration of conduction from atrium to ventricle) [high vagal tone, drugs, aging]
   - 2nd degree (some P waves dont lead to QRS complexes) [aging, injury to AV node]
   - 3rd degree (no transmission from atrium to ventricle)

Question 2

What are symptoms of bradycardia?

Answer 2

1. Lethargy
2. Giddiness
3. Syncope
4. Exertional Dyspnea
5. Asymptomatic

Question 3

How to treat bradycardia?

Answer 3

1. Assess hemodynamic stability
2. Stop medications contributing to bradycardia
3. Atropine
4. Temporary Pacing - transcutaenous or transvenous
5. Permanent pacemaker

Question 4

What are 4 sources of tachycardia?

Answer 4

1. Physiologic
   - sinus tachycardia
   – physiological: exercise, psychological stress/pain
   – pathological: sepsis/pyrexia, hypovolemia, thyrotoxicosis
2. Abnormal Automaticity
   - Atrial Ectopy (P wave inverted); Ventricular Ectopy (QRS broad & bizarre)
   – causes tachycardia when occuring in quick succession
3. Triggered Activity
   - electrolyte anomalies
   - channelopathies
   - injury to myocytes
   - ischemia
   - infection
   - infiltration
   - stretch (chamber enlargement)
   - drugs (anti-arrythmics)
4. Re-entry
   - scar-related reentry: islands that do not allow conduction, set up circuits for conduction instead of going through myocardium
   – Atrial Flutter (Saw-tooth baseline, no P waves; associated with cardiac failure, atrial surgery, mitral valve disorders)
   – Supraventricular Tachycardia (QRS complex broad & bizarre)
5. Disorganised Activity
   - Atrial Fibrillation (No P waves, Fibrillating Baseline); associated with cardiac failure, mitral valve disorders, thyrotoxicosis, ischemic heart disease, HTN, chronic lung disease, aging
   - Ventricular Fibrillation (structurally abnormal heart = acute MI, HF, Cardiomyopathies, hyperkalemia, structurally normal heart = inherited channelopathies [long QT, Brugada])

Question 5

What are the symptoms of tachycardia?

Answer 5

1. Palpitations
2. Giddiness
3. Syncope
4. Cardiac Arrest
5. Asymptomatic

Question 6

How to treat tachycardia?

Answer 6

1. Assess hemodynamic status
   - hemodynamically unstable: DC cardioversion/defibrillation
   – VF, VT, AF with rapid ventricular response, Supraventricular Tachycardia
2. Implantable cardiac defibrillators
3. Medications
4. Electrophysiology study & ablation