Arrhythmias

Cardiac arrythmias can be classified into two major categories: Tachyarrhythmias (> 100 bpm) and Bradyarrhythmias. (< 60 bpm). Arrhythmias are caused by abnormal impulse initiation or abnormal impulse conduction. The risk factors for these abnormal electrical events include yet are not limited to:

Structural heart disease
Coronary Artery Disease
Cardiomypathies
Valvular abnormalities
Electrolyte imbalances
Medications
Congenital defects
Autonomic nervous system imbalances
Viruses

The primary goal in managing any arrhythmia is to assure hemodynamic stability. A patient's perfusion status at time of arrhythmia diagnosis will be one of the initial determinates as to the course of therapy chosen.

Tachyarrhythmias

Tachyarrhythmias can occur in the supraventricular region or in the ventricles

Supraventricular tachyarrhythmias include:

Atrial fibrillation
Atrial flutter
SVT (supraventricular tachycardias

Ventricular tachyarrhythmias include:

Ventricular flutter
Ventricular fibrillation

Bradyarrhythmias & Heart Block

Bradyarrhythmias can be secondary to sinus node (SA) dysfunction or atrioventricular node (AV) conduction problems.

Acute causes include:

Acute coronary syndrome
Electrolyte abnormalities
Medications
Hypothermia
Increased intracranial pressure
High vagal tone
Poor conduction s/p cardiac interventions

Acute on chronic causes include:

Worsening / exacerbation of infiltrative disease
Conduction system fibrosis
Sleep apnea

Sinus node dysfunction will often resolve with treatment of the inciting source. In instances where this is not the case, short-term or long-term atrial pacing may be indicated.

AV Nodal Block

First Degree: prolonged P-R interval, all impulses go through

Second Degree: prolonged P-R interval, some impulses are blocked

Mobitz type I - Progressive PR interval lengthening until a beat is dropped
Mobitz type II - signals are intermittently dropped w/o progressive lengthening of PR intervals

Third Degree: complete heart block, -- likely need pacemaker

Antiarrhythmic Medications

There are four classes of antiarrhythmic agents for tachycardia:

Class I: Sodium Channel Blockers

Lidocaine
Flecanide
Propafenone

Class II: Beta Blockers

Atenolol
Metopralol

Class III: Potassium Channel Blockers

Amiodarone
Sotalol
Ibutilide

Class IV: Calcium Channel Blockers

Diltiazem
Verapamil