Rapid review I: fast rhythms and the four that arrest

METHOD BAR. Read every strip through the same five questions, in this order and no other: rate, regularity, P waves, PR interval, QRS width. Then look at the patient.

1 · Sinus tachycardia

• Rate 101 to 150 per minute. Regular. One upright uniform P before every QRS. PR 0.12 to 0.20 second, constant. QRS less than 0.12 second.
• Priority: treat the cause, not the number. Look for fever, pain, hypovolemia, bleeding, hypoxia, anxiety, and stimulants. Reassess after the cause is addressed.

2 · Atrial fibrillation with rapid ventricular response

• Ventricular rate above 100, often 110 to 180. Irregularly irregular. No discernible P waves over a fibrillatory baseline. PR not measurable. QRS less than 0.12 second.
• Priority: assess perfusion and level of consciousness, compare apical and radial pulses for a deficit, and ask when it started, because onset time drives the clot decision. The lost atrial kick costs output and the stasis makes clot. Assess for new stroke signs at every round.

3 · Atrial flutter

• Atrial rate about 250 to 350 per minute drawn as sawtooth waves; ventricular rate depends on the conduction ratio, classically 150 at two to one. Ventricular response usually regular. Flutter waves replace P waves. PR not measurable. QRS less than 0.12 second.
• Priority: same clot risk as fibrillation. Count the ventricular rate rather than the flutter waves, and assess perfusion.

4 · Supraventricular tachycardia

• Rate 150 to 250 per minute. Regular. P waves not visible, buried in the preceding T. PR not measurable. QRS less than 0.12 second.
• Priority: if stable, a vagal maneuver is attempted first when ordered. Keep the patient monitored with a strip running. If adenosine is ordered, warn the patient about flushing, chest tightness, and a brief pause, and have emergency equipment at hand.

5 · Premature ventricular contractions

• Underlying rate variable, irregular where the ectopic falls. No P before the early beat. PR absent for that beat. QRS 0.12 second or wider, bizarre, with the T deflected opposite and a full compensatory pause.
• Priority: palpate whether the ectopic beats perfuse, check oxygenation, and review potassium and magnesium at → BOOK 07 · P4. Report runs of three or more, couplets, new multiform beats, and any that land on a T wave.

6 · Monomorphic ventricular tachycardia

• Rate 100 to 250 per minute, commonly 150 to 200. Regular. No visible P waves. PR not measurable. QRS 0.12 second or wider, every complex identical.
• Priority: check a pulse before anything else. A pulse present with instability points to synchronized cardioversion; no pulse moves this to the arrest column.

7 · Torsades de pointes

• Rate about 200 to 250 per minute. Irregular. No P waves. PR not measurable. QRS wide, with amplitude and axis twisting around the baseline, preceded by beats with a visibly long QT.
• Priority: magnesium per order, stop the medication that prolonged the QT, and review the whole list including the ones that are not cardiac. Send electrolytes. If pulseless, this is defibrillated, not synchronized.

8 · The four that arrest

• Ventricular fibrillation: no measurable rate, chaotic, no P waves, no PR, no identifiable QRS. Shockable.
• Pulseless ventricular tachycardia: the strip of item 6 with no pulse at the neck. Shockable.
• Pulseless electrical activity: an organized rhythm on the screen, any rate or width, with no palpable pulse. Not shockable. The screen lies; the neck tells the truth.
• Asystole: rate of zero, no P, no PR, no QRS. Confirm in two leads and check the leads and gain before you believe it. Not shockable.
• Priority for all four: confirm pulselessness, call for help, start compressions, and attach the defibrillator. Know which two are shockable before you touch the machine.

Memory hookPULSE, THEN SYNC. NO PULSE, THEN SHOCK. Registered as B8-SYNC-SHOCK.

Any infusion rate belongs to → BOOK 06 · P6.

Takeawaythe strip names the rhythm, the patient names the priority, and the pulse check is what connects them.