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Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Bradycardia

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In one line

·A heart rate below 60 beats per minute is called a slow heart rate (bradycardia). It becomes an emergency when the slow rate causes symptoms — dizziness, fainting, chest pain, or confusion — because those symptoms mean the body is not getting enough blood. An electrocardiogram (ECG; a tracing of the heart's electrical signals) shows whether the slow rate is coming from the heart's natural pacemaker, from a traffic jam in the heart's wiring, or from a complete electrical block.

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Normal physiology

·The heart beats because of an electrical system. At the top of the heart, a natural pacemaker called the SA node fires a spark 60 to 100 times every minute. That spark travels down to a relay station (the AV node), then races along wires (the bundle of His and bundle branches) to the bottom pumping chambers (the ventricles) so they squeeze and push blood out to the body. Every heartbeat is one cycle: spark, travel, squeeze, pump.

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What goes wrong

·A slow heart rate (Bradycardia) happens when the heart's electrical system slows down or gets blocked. The break can be at the top (the pacemaker fires too slowly or stops), in the middle (the relay station blocks signals), or below (the wires are damaged so signals never reach the pumping chambers). Often one cause explains all the symptoms together.

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Hallmark signs

·Slow heart rate (below 60 beats per minute at rest)
·Feeling dizzy or lightheaded
·Extreme tiredness or weakness
·Shortness of breath, especially with activity
·Chest discomfort or pressure
·Fainting or near-fainting spells
·Confusion or trouble concentrating
·Cannon A waves seen in the neck veins (during complete heart block)

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Red flags · escalate now

·Fainting or blackout spells
·Chest pain or pressure
·Severe shortness of breath at rest
·Sudden confusion or slurred speech
·Heart rate below 40 beats per minute with symptoms

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Workup

·12-lead electrocardiogram (ECG)
·Serum electrolytes (sodium, potassium, calcium, magnesium)
·Thyroid-stimulating hormone (TSH) and free T4
·Troponin I or T
·Medication levels: digoxin level, review of beta-blocker or calcium channel blocker dosing
·Chest X-ray

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Treatment

·Atropine 1 mg IV push, repeat every 3 to 5 minutes up to a total dose of 3 mg
·Transcutaneous pacing—large adhesive pads placed on the chest and back deliver electrical pulses that force the heart to beat at a set rate
·Stop the drug causing a slow heart rate (bradycardia)—immediately hold beta-blockers (e.g., metoprolol, atenolol), non-dihydropyridine calcium channel blockers (e.g., diltiazem, verapamil), or digoxin
·Glucagon 3 to 5 mg IV bolus followed by infusion of 3 to 5 mg/hour for beta-blocker overdose; calcium chloride 1 g IV (10 mL of 10% solution) or calcium gluconate 3 g IV (30 mL of 10% solution) for calcium channel blocker overdose
·Epinephrine infusion (2 to 10 micrograms per minute) or dopamine infusion (5 to 20 micrograms per kilogram per minute) if atropine and pacing do not restore adequate blood pressure
·Permanent pacemaker implantation for symptomatic sinus node dysfunction (sick sinus syndrome), Mobitz II second-degree AV block, or complete (third-degree) heart block
·Treat underlying causes: levothyroxine for hypothyroidism, coronary revascularization (PCI or CABG) for starved blood flow (ischemia) causing a slow heart rate (bradycardia), dialysis or insulin-glucose-calcium for severe high potassium (hyperkalemia)

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NCLEX trap

·Atropine only speeds up the AV node itself—the gate between the top and bottom chambers of the heart. If the problem is in the wires below that gate (infranodal block), atropine can make things worse and the heart may stop completely. Always look at the ECG pattern first to find where the slowdown is happening.
·A slow heart rate is only a problem if the patient shows signs that not enough blood is reaching the body—fainting, dangerously low blood pressure, confusion, or chest pain. A healthy athlete with a resting heart rate of 45 is fine and needs nothing. Treat the patient, not just the number on the monitor.
·Many medicines slow the heart on purpose: beta-blockers (like metoprolol), calcium channel blockers (like diltiazem), and digoxin. Always ask what pills the patient takes. Often the cause is not a sick heart but too much of a medicine the patient is already on.
·There is a clear order: atropine first if the AV node is the problem, then transcutaneous pacing (sticky pads on the chest that shock the heart into beating faster) if atropine does not work or the block is below the node, and finally dopamine or epinephrine drips only if those steps fail. Use the right tool for the right problem.
·Dizziness is the body's alarm that not enough blood is reaching the brain because the heart is pumping too slowly. Fix the heart rate—by removing the medicine causing it, giving atropine, or pacing—and the dizziness will go away on its own. Do not mask the alarm; fix the fire.
·A slow heart rate plus a stretched-out space between the QRS and the next heartbeat (long QT) sets the stage for torsades de pointes—a chaotic, deadly rhythm that can stop the heart. Do not give any medicine that makes the QT even longer. Recognize this dangerous pattern and act to prevent the next step.

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