(Antiarrhythmics are the drugs that affect the action potential of cardiac cells and are used to treat arrhythmias and restore normal rate and rhythm.)
Antiarrhythmics affect the action potential of the cardiac cells by altering their automaticity, conductivity, or both. Because of this effect, antiarrhythmic drugs can also produce new arrhythmias—that is, they are proarrhythmic. Antiarrhythmics are used in emergency situations when the hemodynamics arising from the patient’s arrhythmia are severe and could potentially be fatal.
Most antiarrhythmics can aggravate existing arrhythmias or cause new ones. They also may produce CNS disturbances, such as dizziness or fatigue; GI problems, such as nausea, vomiting, or altered bowel elimination; hypersensitivity reactions; and hypotension. Some antiarrhythmics may worsen heart failure. Class II drugs may cause bronchoconstriction.
Life-threatening recurrent ventricular fibrillation or recurrent hemodynamically unstable ventricular tachycardia unresponsive to adequate doses of other antiarrhythmics or when alternative drugs can’t be tolerated.
Effects result from blockade of potassium chloride leading to a prolongation of action potential
• CNS: fatigue, malaise, tremor
• CV: hypotension, bradycardia, arrhythmias, heart failure, heart block, sinus arrest
• EENT: asymptomatic corneal microdeposits, visual disturbances
• GI: nausea, vomiting
• Hematologic: coagulation abnormalities
• Hepatic: hepatic failure, hepatic dysfunction
• Metabolic: hypothyroidism, hyperthyroidism
• Respiratory: acute respiratory distress syndrome, severe pulmonary toxicity
• Skin: photosensitivity, blue-gray skin
2: Flecainide acetate
• Prevention of paroxysmal supraventricular tachycardia in patients without structural heart disease
• Life-threatening ventricular arrhythmias.
A class IC antiarrhythmic that decreases excitability, conduction velocity, and automaticity by slowing atrial, AV node, His-Purkinje system, and intraventricular conduction; prolongs refractory periods in these tissues.
• CNS: dizziness, headache, light-headedness
• CV: new or worsened arrhythmias
• EENT: blurred vision and other visual disturbances
• GI: nausea, constipation, abdominal pain, vomiting, diarrhea
• Respiratory: dyspnea
Ventricular arrhythmias caused by MI, cardiac manipulation, or cardiac glycosides
A class IB antiarrhythmic that decreases the depolarization, automaticity, and excitability in the ventricles during the diastolic phase by direct action on the tissues, especially the Purkinje network.
• CNS: confusion, tremor, stupor, restlessness, light-headedness, seizures, muscle twitching
• CV: hypotension, bradycardia, new or worsened arrhythmias, cardiac arrest
• EENT: tinnitus, blurred or double vision
• Respiratory: respiratory depression and arrest
• Other: anaphylaxis