Why pulseless ventricular tachycardia is a shockable rhythm and how defibrillation helps EMTs.

Which of the following is an example of a shockable rhythm?

• A. Asystole
• B. Pulseless ventricular tachycardia
• C. Bradycardia
• D. Ventricular fibrillation

Answer: (B)

Pulseless ventricular tachycardia is classified as a shockable rhythm because it is characterized by an abnormal rapid heart rate that does not effectively pump blood, leading to a state of cardiac arrest. In this situation, the electrical activity of the heart is chaotic, preventing it from maintaining an adequate output. When you deliver a shock, typically using an automated external defibrillator (AED) or manual defibrillator, it can interrupt that disorganized electrical activity, allowing for the possibility of restoring a normal rhythm. On the other hand, asystole represents a complete absence of electrical activity in the heart and therefore cannot be treated with a shock. Bradycardia involves a slower than normal heart rate but does not inherently mean there's no pulse; shock is not indicated here unless the bradycardia leads to hemodynamic instability. Ventricular fibrillation, while also a shockable rhythm, is not the answer in this case because the question asks specifically for an example, and pulseless ventricular tachycardia is the clear choice given the context.

Shockable Rhythms in the Field: What EMTs Need to Know

Let’s set the scene. You’re at a scene, the heart monitor is blinking, and a patient drifts into a dangerous rhythm. Time slows down just enough for you to notice one crucial fact: some rhythms are shockable, and others aren’t. Knowing which is which isn’t trivia—it’s a life-or-death skill that can change the outcome in minutes.

What exactly makes a rhythm “shockable”?

• Here’s the thing: a shockable rhythm is one where delivering a jolt can reset the electrical chaos in the heart, giving it a chance to restart with a more effective rhythm.

• The two most common shockable rhythms you’ll encounter are ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT). Both disrupt the heart’s ability to pump blood, which is exactly why a defibrillator is used—to interrupt the faulty electrical activity and give the heart a fresh chance.

A quick refresher: the two big categories

• Shockable rhythms: ventricular fibrillation and pulseless ventricular tachycardia.

• Non-shockable rhythms: asystole and pulseless electrical activity (PEA), plus certain bradycardias when the pulse remains present and stable.

Let me explain how pulseless ventricular tachycardia fits the bill

Pulseless ventricular tachycardia is a rapid, abnormal heart rhythm that keeps the ventricles firing so fast they can’t fill and eject blood effectively. The result? No meaningful pulse, no adequate blood flow, and a heart that’s not delivering oxygen to the brain and kidneys in a timely way.

Why is pVT a standout example? Because it’s fast and chaotic enough that a single defibrillation can interrupt the disorganized activity, letting the heart reset into a rhythm that has a pulse again. You’re aiming to restore a perfusing rhythm, not just to “wake up” the electrical activity for the heck of it. In other words, the shock acts like a reset button for the heart’s electrical system.

A caveat that people often mix up: ventricular fibrillation (VF) is also shockable, and it’s a frequent culprit in cardiac arrest. The difference lies in how the chaos presents on the monitor. VF looks like a squiggle—no organized rhythm at all. pVT, by contrast, shows a rapid, somewhat regular rhythm that doesn’t produce a pulse. The exam-like question you might see here is not asking for a trick; it’s highlighting one clear example of a shockable rhythm, and pulseless VT is a textbook case.

What happens on the chest when you decide to shock?

• Step 1: Confirm there’s no pulse and the patient is in cardiac arrest. Don’t skip this—pulses can be tricky to feel, and a mistaken pulse check can waste life-saving seconds.

• Step 2: Check the rhythm on the monitor. If the rhythm is VF or pVT, you’re in shock territory.

• Step 3: Deliver a defibrillation shock using an AED or a manual defibrillator, following the device’s prompts and your protocol.

• Step 4: Immediately resume high-quality CPR after the shock, giving priority to minimizing pauses. CPR should keep oxygen flowing to the brain while the heart’s electrical system restarts.

• Step 5: Reassess quickly, and repeat as guidelines dictate. If another shock is indicated and you’ve got it ready, go for it.

A few practical notes you’ll hear in the field

• The energy dose matters, but so does timing. Modern AEDs walk you through the sequence with clear prompts, but your on-scene judgment matters just as much. When to shock, when to pause CPR, and how long to wait before rechecking—these aren’t “tricks”; they’re the rhythm of a life-saving response.

• Don’t chase a pulse forever. If pulses return, switch to compressions only as needed to stabilize the patient and reassess gradually. If the rhythm shifts back to non-perfusing, you may need to shock again according to protocol.

• If you’re dealing with a child, the approach shares the same core ideas but with pediatric energy dosing, pad placement adjustments, and a careful eye on the child’s physiology. The goal remains the same: restore a perfusing rhythm with the fewest interruptions possible.

Why we don’t shock certain rhythms

Asystole is the opposite of a shockable rhythm. It means there’s no electrical activity to interrupt—the heart isn’t firing at all. Shocking in this scenario does not help; it’s like trying to wake a light that’s completely off. In asystole, the focus is on high-quality CPR and correct reversible causes while monitoring for any signs that the heart’s electrical activity might return.

Bradycardia—slow heart rate—gets treated differently. If the patient’s pulse is present and blood pressure is stable, a shock isn’t indicated. If bradycardia leads to instability or arrest, the situation changes, and the team may pivot to pacing or medications to support heart rate and perfusion. It’s a reminder that rhythm alone isn’t the full story; perfusion and patient stability matter just as much.

A helpful analogy

Think of the heart as a three-ring circus with a tiny conductor at the center. The rhythm is the music—the faster or more chaotic the tempo, the harder it is for the conductor to keep the band in sync. A defibrillator is like hitting the reset button on the entire orchestra. When it works, the music comes back in harmony, and the crowd (the organs) starts to get what they need again.

Real-world rhythm-reading tips you can actually use

• Always verify a pulse. A pulse check isn’t optional—it’s a critical gatekeeper. A rhythm that looks dangerous on the monitor might still have a pulse. The pulse is your anchor for deciding whether to shock.

• Different devices, same goal. AEDs are built for quick, decisive action, while manual defibrillators give you more control in complex situations. Learn both interfaces, because you never know what the scene will hand you.

• Expect interruptions. High-quality CPR is a rhythm too—minimize pauses during rhythm checks and defibrillation cycles. A few seconds here and there add up fast, so plan ahead and coordinate with your team.

• Communicate clearly. In the heat of the moment, a simple “Shock advised—resume CPR” communicates what’s next and reduces confusion. Clear roles help the team stay in sync.

• Stay curious about the data. The monitor can show trends that hint at what’s happening under the surface—ischemia, electrolyte disturbances, or drug effects. Understanding these cues helps you respond more effectively.

Digressions that still connect back

While we’re on the topic, let me throw in a quick reality check about how this plays out in the field. You’re not just pushing buttons; you’re reading bodies. A patient’s skin color, breath sounds, and level of agitation all tie into whether a rhythm is truly shockable and whether your interventions are working. And yes, the adrenaline surge in the moment is real. It’s not a weakness to feel it; it’s a reminder that you’re in a high-stakes environment where calm, precise actions win the day.

Key takeaways that stick

• Shockable rhythms include ventricular fibrillation and pulseless ventricular tachycardia. Both are emergencies that require defibrillation alongside chest compressions.

• Pulseless ventricular tachycardia is a clear example of a shockable rhythm because it disrupts effective blood flow and can often be reset by a defibrillation shock.

• Asystole and PEA are non-shockable in most scenarios; the emphasis there is CPR and identifying reversible causes, not delivering a shock.

• For bradycardia with a pulse, shock is not the default move. Treat the instability with pacing or medications as appropriate.

• In the field, the best outcomes come from rapid rhythm assessment, minimizing interruptions, and clear team communication.

Wrapping it up with a practical mindset

If you’re navigating a chaotic scene, remember this: the rhythm on the monitor tells a story, but it’s the patient who completes the narrative. A properly timed shock can restore a perfusing rhythm; a well-executed CPR sequence buys essential minutes while the heart stabilizes. The math of emergency care isn’t fancy; it’s about making the right call quickly, sticking to the plan, and being ready to adapt as conditions change.

So, next time you see a shockable rhythm on the screen, you’ll know what to do with confidence. You’ll recognize that pulseless ventricular tachycardia isn’t just a line on a monitor—it’s a critical moment that, with the right action, can flip the outcome from crisis to a fighting chance at recovery. And that’s the heart of it: every shock is a chance, every breath a reminder that timing, team work, and clear decisions are why EMTs stand between danger and hope.