Tachycardia

Treatments

Treatment of tachycardia is usually directed at chemical conversion (with antiarrythmics), electrical conversion (giving external shocks to convert the heart to a normal rhythm) or use of drugs to simply control heart rate (for example as in atrial fibrillation).

The treatment modality used depends on the type of tachycardia and the hemodynamic stability of the patient. If the tachycardia originates from the sinus node (sinus tachycardia), treatment of the underlying cause of sinus tachycardia is usually sufficient. On the other hand, if the tachycardia is of a potentially lethal origin (ie: ventricular tachycardia) treatment with anti arrhythmic agents or with electrical cardioversion may be required. Below is a brief discussion of some of the main tachyarrhythmias and their treatments.

The electrocardiac management of atrial fibrillation and atrial flutter is either through medications or electrical cardioversion. Pharmacologic management of these arrhythmias typically involves diltiazem or verapamil as well as beta-blocking agents such as atenolol. The decision to use electrical cardioversion depends heavily on the hemodynamic stability of the presenting patient; in general those patients who are unable to sustain their systemic functions are electrically converted although conversion to a normal sinus rhythm can be performed with amiodarone. An interesting type of atrial fibrillation which must be carefully managed is when it appears in combination with Wolff-parkinson White. In this case, calcium channel blockers, beta-blockers and digoxin must be avoided to prevent precipitation of ventricular tachycardia. Here, procainamide or quinidine are often used. Of note: patients who have been in atrial fibrillation for more than 48 hours should not be converted to normal sinus rhythm unless they have been anti-coagulated to an INR of 2-3 for at least 4 weeks.

In the case of narrow complex tachycardias (juntional, atrial or paroxysmal), the treatment in general is to first give the patient adenosine (to slow conduction through the AV node) and then perform vagal maneuvers to slow the rhythm. If this does not convert the patient, amiodarone, calcium channel blockers or beta-blockers are commonly employed to stabilize the patient. Again as in atrial fibrillation, if a patient is unstable, the decision to electrially cardiovert him/her should be made.

With wide complex tachyarrhythmias or ventricular tachyarrhythmias, in general most are highly unstable and cause the patient significant distress and would be electrically converted. However one notable exception is monomorphic ventricular tachycardia which patients may tolerate but can be treated pharmacologically with amiodarone or lidocaine.

Above all, the treatment modality is tailored to the individual, and varies based on the mechanism of the tachycardia (where it is originating from within the heart), on the duration of the tachycardia, how well the individual is tolerating the fast heart rate, the likelihood of recurrence once the rhythm is terminated, and any co-morbid conditions the individual is suffering from.

ACC / AHA Guidelines- Recommendations for Permanent Pacemakers That Automatically Detect and Pace to Terminate Tachycardias (DO NOT EDIT)

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Class IIa 1. Permanent pacing is reasonable for symptomatic recurrent SVT that is reproducibly terminated by pacing when catheter ablation and/or drugs fail to control the arrhythmia or produce intolerable side effects. (Level of Evidence: C) Class III 1. Permanent pacing is not indicated in the presence of an accessory pathway that has the capacity for rapid anterograde conduction. (Level of Evidence: C)

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Sources

• The ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities