Managing tachycardia

When the heart rate goes over 100 beats per minute, we can label it as tachycardia.
Tachyarrythmias have a rate of over 150 beats per minute usually.
Tachycardia can be a supraventricular or ventricular.
Regardless of the types, the management is similar. Firs step is identifying if the tachycardia patient is stable or unstable.

Stable Vs Unstable tachycardia

On receiving a patient, you can proceed in your regular fashion of speaking to the patient and checking vitals on a bed.
Give supplemental oxygen if saturations are below 94% on room air.
Take a 12 lead ECG if time permits.
Gain IV – Intravenous access (or Intra-osseous if IV is not possible).
Use the following signs to differentiate stable or unstable (Similar signs are used in tachycardia as well to differentiate stable and unstable bradycardia.)
If the patient does not have any of the 5 signs listed below, it is a case of Stable tachycardia.
If the patient happens to have even one of the 5 listed signs, label it as Unstable tachycardia.

Signs of instabilityAssociated symptoms
1. Ischemic chest painChest pain or upper abdominal pain.
2. Signs of heart failureLeft heart failure: Crackles in lungs
Right: Pedal edema, facial puffiness, ascites.
3. HypotensionSweating, giddiness
4. Signs of shockCold clammy peripheries, sweating, bluish fingers or oral mucosa
5. Altered mental statusDrowsiness, Disorientation, or coma.

Stable tachycardia – Medical therapy

For stable tachyarrythmias, we can choose to give medical therapy.
First we need to see if it’s a narrow complex ( less than 3 small boxes / 0.12 seconds) or broad complex ( more than 3 small boxes / 0.12 seconds) rhythm on ECG.

Narrow–QRS-complex (SVT) tachycardias (QRS <0.12 second), in order of frequency
Sinus tachycardia
– Atrial fibrillation
– Atrial flutter
– AV nodal reentry
– Accessory pathway–mediated tachycardia
– Atrial tachycardia (including automatic and reentry forms)
– Multifocal atrial tachycardia (MAT)
– Junctional tachycardia (rare in adults)
– Wide–QRS-complex tachycardias (QRS ≥0.12 second)
– Ventricular tachycardia (VT) and ventricular fibrillation (VF)
– SVT with aberrancy
– Pre-excited tachycardias (Wolff-Parkinson-White [WPW] syndrome)
– Ventricular paced rhythms

1. Attempt Vagal maneuvers ( Valsalva maneuver or carotid sinus massage ), which can help in 25% of cases.
2. In case the rhythm persists and it is narrow regular, you may choose Adenosine 6mg RAPID IV PUSH followed by flush. We can escalate the dose to 12mg and another 12mg if 6mg doesn’t help. (More details on how to deliver in pharmacology module)

3. If adenosine fails, or discloses a different form of SVT (such as atrial fibrillation or flutter), it is reasonable to use longer-acting AV nodal blocking agents, such as the nondihydropyridine calcium channel blockers (verapamil and diltiazem) or β-blockers (metoprolol, atenolol, propranolol, esmolol, and labetolol). (Dosing details in pharmocology module)
4. Involve an expert.

Wide QRS complex stable tachycardias (QRS >0.12 second)
The most common forms of wide-complex tachycardia are:
VT or VF
SVT with aberrancy
Pre-excited tachycardias (associated with or mediated by an accessory pathway)
Ventricular paced rhythms

*** If you see VT on monitor, first check PULSE. (VT with pulse and without pulse are managed differently ***
Adenosine can be considered if regular and monomorphic.
Start an anti-arhythmic infusion and speak to an expert.
Choices of anti-arrhythmics:
– procainamide, amiodarone, or sotalol can be considered. 
Procainamide and sotalol should be avoided in patients with prolonged QT.
If one of these antiarrhythmic agents is given, a second agent should not be given without expert consultation. 

If antiarrhythmic therapy is unsuccessful, cardioversion or expert consultation should be considered. 

Unstable tachycardia – Synchronized cardioversion

As detailed in the beginning, if it turns out to be an unstable tachyarrythmia, immediate synchronized cardioversion is recommended.
Before the procedure, consider explaining to the patient and obtaining consent.
Apart from consent, to prevent discomfort to the patient, consider sedating.
Now, choose the right energy on the defibrillator and press the SYNC button.

Energy requirements:
Narrow – regular rhythms – 50-100J (start at 50, escalate as needed)
Narrow – irregular – 120-200J
Wide – regular – 100J (escalate to 150 or 200 if needed)
Wide – irregular – 200J (or maximum energy available on machine without SYNC mode)

Charge the machine and announce CLEAR (loudly) before pressing the SHOCK button.
After delivering a shock, you should immediately check the monitor for a change in rhythm and check patient’s pulse.

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