Impulse initiation: Sinus arrest, sinus bradycardia, sinoatrial exit block.

Impulse conduction: Heart block (Types I, II, III)

1) Increased automaticity (impulses come from somewhere other than sinus node). EXAMPLES: Atrial Tachycardia - abnormal pulses coming from the atria. Junctional tachycardia - abnormal AV pulses.

Ventricular tachycardia - abnormal pulses coming from ventricle.

2) Triggered activities in phase 3 or 4 (repolarization). EXAMPLES: Early afterdepolarization (EAD) - interrupts phase 3. Delayed afterdepolarization (DAD) - interrupts phase 4 of AP.

3) Impulse conduction through tissues with different conductivities causing reentry circuit.

Atrial Tachycardia - abnormal pulses coming from the atria.

Junctional tachycardia - abnormal AV pulses.

Ventricular tachycardia - abnormal pulses coming from ventricle.

Cells with conduction properties remain around tricuspid and mitral annuli during development. Conduction to ventricular tissue is faster than AV node.

Look for Delta Wave on EKG.

Reentry circuit around mitral, tricuspid annulus.

Fast, but regular ventricular response.

Atrial rate is ~300 bpm.

Sawtooth pattern.

NEED: 1) substrate - scar tissue, slow/fast pathway.

2) trigger - electrolyte imbalance, acid/base imbalance.

Primarily Sodium Channel Blockers:

1a) Quinidine, procainamide, disopyramide.

1b) Lidocaine, mexiletine, tocainide.

1c) Flecainide, propafenone.

2) Beta blockers

3) K channel blockers

Amiodarone, bretylium, sotalol, ibutilide, dofetilide.

4) CCBs

Verapamil, diltiazem.

NOT CLASSIFIED: Digoxin, Adenosine.

MECH: Acts on adenosine receptors in atrium, SA node and AV node. Activates outward K flux and inhibition of calcium current causing hyperpolarization which slows automaticity and AV conduction.

USE: Acute termination of supraventricular tachycardia (SVT).

1/2 life only 10 seconds!! Vaugh Williams 0.

MECH: Na channel blocker, prolongs QRS, slowing conduction.

AE: Hypotension, lupus (with long-term treatment), inpatient only.

Metabolized to N-acetlyprocainamide which has class 3 properties (K channel blockade). Vaugh Williams 1a.

MECH: Blocks Na, K channels and alpha adrenergics.

USE: Atrial fibrillation. Also Brugada's syndrome (Na ion channel mutation) and short QT syndrome (K channel mutation).

AE: Naus., diarrhea, Quinidine syncope (polymorphic v-tach secondary to prolongued QT interval)--monitor patients carefully. Vaugh Williams class 1a.

MECH: Direct vagal blocker.

USE: Baseline bradycardia, Ventricular tachycardia.

AE: Urinary retention, blurred vision, exacerbated glaucoma (anticholinergic). Vaugh Williams class 1a.

MECH: Na channel blocker. Works preferentially on  ischemic ventricular myocardium.

USE: Ventricular Tachycardia.

AE: neurological: tremor, slurred speach, convulsions and seizure. Metabolized in liver (therefore, IV only)--reduce dose in CHF and liver disease patients. ONLY I.V. Vaugh Williams class 1b.

MECH: Oral Lidocaine. Same mech.

USE: Ventricular tachycardia in ischemic tissue. Also for use in patients on drugs that prolong QT interval.

AE: GI upset. Vaugh WIlliams class 1b.

MECH: Potent Na channel blocker which prolongs atrial refractory time and QRS interval.

USE: Premature Ventricular Contraction (PVC), A-Fib.

CONTRA: DO NOT use in patients with CAD, cardiomyopathies or LV dysfunction.

Vaugh Williams class 1c. 5-hydroxy Propafenone is an active metabolite.

MECH: Potent Na channel blocker which prolongs atrial refractory time and QRS interval.

USE: Premature Ventricular Contraction (PVC), A-Fib.

CONTRA: DO NOT use in patients with CAD, cardiomyopathies or LV dysfunction.

Vaugh Williams class 1c.

MECH: Increase refractory time in AV node.

AE: Bronchospasm, bradycardia.

MECH: Blocks, K, Na, Ca and Beta receptor.

USE: Ventricular arrythmia, A-Fib.

AE: Thyroid imbalance (contains iodine), hypotension due to vasodilation. Liver, lung toxicity as well.

All 4 class actions but considered class III.

MECH: Like Amioderone but more tolerable due to its lack of iodine.

USE: A Fib (NOT effective in LV dysfunction).

Class III.

MECH: K channel blocker which prolongs Ventricular action potential (APD), prolongs Effective refractory period (ERP). Also a beta blocker.

USE: Ventricular and atrial arrythmias.

Renally adjust dosage. Class III.

MECH: Pure blockage of IKr channel (phase 3).

USE: A-Fib (in hospital only). Can be used for patients with A-fib and ischemic cardiomyopathy and CAD.

Potential for developing Toursades so watch QT closely.

MECH: IKr blocker, also activates inward Na current.

USE: Atrial flutter, Atrial Fibrillation (ONLY I.V.).

AE: 4% develop Torsades--watch carefully for 4 hrs.

MECH: L-type Ca channel blocker. Slows impulse in SA and AV node by increasing conduction time and increasing refractory time.

USE: SVT

AE: Negative inotrope (watch in HF), sinus arrest, AV block.

MECH: L-type Ca channel blocker. Slows impulse in SA and AV node by increasing conduction time and increasing refractory time.

USE: SVT

AE: Negative inotrope (watch in HF), sinus arrest, AV block.