Tachycardia

TACHYCARDIA

Tachycardia is a heart rate of greater than 100 beats per minute. When the heart beats too quickly, there is a shortened relaxation phase. This causes two main problems: the ventricles are unable to fill completely, causing cardiac output to decrease; and the coronary arteries receive less blood, causing supply to the heart to decrease.

Tachycardia is classified as stable or unstable.
Heart rates greater than or equal to 150 beats per minute usually cause symptoms.
Unstable tachycardia always requires prompt attention.
Stable tachycardia can become unstable.

Symptoms of Tachycardia

Hypotension
Sweating
Pulmonary edema/congestion
Jugular venous distension

SYMPTOMATIC TACHYCARDIA WITH HEART RATE > 150 BPM

1. If the individual is unstable, provide immediate synchronized cardioversion.

Is the individual’s tachycardia producing hemodynamic instability and serious symptoms?
Are the symptoms (i.e., pain and distress of acute myocardial infarction (AMI)) producing the tachycardia?

2. Assess the individual’s hemodynamic status and begin treatment by establishing IV, giving supplementary oxygen, and monitoring the heart.

Heart rate of 100 to 130 bpm is usually the result of an underlying process and often represents sinus tachycardia. In sinus tachycardia, the goal is to identify and treat the underlying systemic cause.
Heart rate greater than 150 bpm may be symptomatic; the higher the rate, the more likely the symptoms are due to the tachycardia.

3. Assess the QRS Complex.

If at any point you become uncertain or uncomfortable during the treatment of a stable patient, seek expert consultation.

Adenosine may cause bronchospasm; therefore, adenosine should be given with caution to patients with asthma.

Synchronized cardioversion is appropriate for treating wide complex tachycardia of unknown type. Prepare for synchronized cardioversion as soon as a wide complex tachycardia is detected.

REGULAR NARROW COMPLEX TACHYCARDIA (PROBABLE SVT)

Attempt vagal maneuvers.
Obtain 12-lead ECG; consider expert consultation.
Adenosine 6 mg rapid IVP; if no conversion, give 12 mg IVP (second dose); may attempt 12 mg once.

IRREGULAR NARROW COMPLEX TACHYCARDIA (PROBABLE A-FIB)

Obtain 12-lead ECG; consider expert consultation.
Control rate with diltiazem 15 to 20 mg (0.25 mg/kg) IV over two minutes or beta-blockers.

REGULAR WIDE COMPLEX TACHYCARDIA (PROBABLE VT)

Obtain 12-lead ECG; consider expert consultation.
Convert rhythm using amiodarone 150 mg IV over 10 minutes.
Perform elective cardioversion.

IRREGULAR WIDE COMPLEX TACHYCARDIA

Obtain 12-lead ECG; consider expert consultation.
Consider anti-arrhythmic.
If Torsades de Pointes, give magnesium sulfate 1 to 2 gm IV; may follow with 0.5 to 1 gm over 60 minutes.

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