# A nurse is caring for a patient who suddenly develops ventricular tachycardia with a pulse. The patient is conscious but reports chest pain and dizziness. Which intervention should the nurse implement first?

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> subject: Adult Health

## 문제

A nurse is caring for a patient who suddenly develops ventricular tachycardia with a pulse. The patient is conscious but reports chest pain and dizziness. Which intervention should the nurse implement first?

## 보기

1. Administer amiodarone 150 mg IV push immediately
2. Prepare for immediate defibrillation at 200 joules
3. Obtain a 12-lead ECG to confirm the rhythm
4. Administer oxygen and prepare for synchronized cardioversion **✔ 정답**

**정답: 4**

## 해설

For stable ventricular tachycardia with a pulse, the priority is oxygen administration and preparation for synchronized cardioversion to restore cardiac output. Other options are inappropriate: amiodarone is for stable VT without immediate instability, defibrillation is for pulseless rhythms, and ECG confirmation delays urgent care.

## 심화 해설

Understanding the Clinical Scenario

The patient is experiencing ventricular tachycardia (VT) with a pulse. The presence of a pulse and consciousness, despite symptoms of chest pain and dizziness, classifies this as unstable tachycardia. The immediate goal is to restore a stable cardiac rhythm and adequate perfusion. The patient’s instability is evidenced by the reported chest pain (indicating myocardial ischemia) and dizziness (indicating cerebral hypoperfusion). This is a medical emergency where a delay in treatment can lead to deterioration into pulseless VT or ventricular fibrillation.

Analysis of Intervention Options

The priority intervention must directly and rapidly address the unstable rhythm. Let’s evaluate the options in the context of established advanced cardiac life support principles.

- **Option 1: Administer amiodarone 150 mg IV push immediately.** Amiodarone is a first-line antiarrhythmic agent for VT, but its onset of action is not immediate. In an unstable patient, pharmacological intervention is secondary to electrical therapy, which works more rapidly to terminate the arrhythmia.

- **Option 2: Prepare for immediate defibrillation at 200 joules.** Defibrillation is an unsynchronized shock delivered at any point in the cardiac cycle. It is the definitive treatment for pulseless VT and ventricular fibrillation. For a patient with a pulse, an unsynchronized shock carries a significant risk of inducing ventricular fibrillation by delivering energy during the relative refractory period (the T wave), a phenomenon known as R-on-T phenomenon.

- **Option 3: Obtain a 12-lead ECG to confirm the rhythm.** While a 12-lead ECG is valuable for diagnosing the specific type of VT and identifying underlying ischemia, it delays definitive treatment. In an unstable patient, rhythm confirmation via the monitor or a quick rhythm strip is sufficient to proceed with emergency intervention.

- **Option 4: Administer oxygen and prepare for synchronized cardioversion.** This is the correct sequence. Supplemental oxygen is provided to support oxygenation. Synchronized cardioversion is the delivery of a shock that is timed (synchronized) with the patient’s QRS complex. This avoids the vulnerable T wave, making it the safe and effective electrical therapy for unstable tachyarrhythmias with a pulse, including VT.

Why Synchronized Cardioversion is the Priority

The fundamental principle in managing unstable tachycardia with a pulse is immediate synchronized cardioversion. The shock disrupts the re-entrant circuit driving the ventricular tachycardia, allowing the sinoatrial node to resume its role as the primary pacemaker. The synchronization function on the defibrillator delays shock delivery until it detects the R wave, which is critical for safety. Administering sedation is ideal if time and patient condition allow, but in a rapidly deteriorating patient, immediate cardioversion takes precedence.

Pathophysiology and Clinical Reasoning

In ventricular tachycardia, the ventricles contract at a rate typically between 100 and 250 beats per minute. This rapid rate shortens diastolic filling time, which leads to a decrease in stroke volume and cardiac output. The patient’s symptoms of chest pain and dizziness are direct consequences of this compromised hemodynamic state. Chest pain results from reduced coronary artery perfusion during shortened diastole and increased myocardial oxygen demand from the high heart rate. Dizziness is a neurological manifestation of reduced cerebral blood flow. The progression from stable to unstable VT is a continuum, and the presence of these symptoms signals that the body’s compensatory mechanisms are failing. Immediate restoration of a perfusing rhythm via synchronized cardioversion is the only intervention that can rapidly reverse this dangerous cascade.

## 임상 시나리오

Unstable VT with a Pulse: Immediate ActionPrioritizing Electrical Therapy over Pharmacology
For a patient in ventricular tachycardia who is unstable (e.g., chest pain, dizziness, hypotension), the priority intervention is immediate synchronized cardioversion. The presence of a pulse dictates the use of synchronized rather than unsynchronized shocks.

Administer oxygen and ensure IV access, but do not delay cardioversion. The initial shock for a regular, monomorphic VT is typically 100 Joules, escalating as needed. If the patient becomes pulseless, the algorithm switches to defibrillation immediately.

CautionDo not confuse defibrillation with synchronized cardioversion. Defibrillation is unsynchronized and reserved for pulseless rhythms (VT/VF). Using it on a patient with a pulse can precipitate cardiac arrest by delivering a shock on the T-wave.

## 핵심 개념

- **Synchronized Cardioversion** — Delivery of a timed electrical shock synchronized with the QRS complex to convert an unstable tachyarrhythmia with a pulse back to sinus rhythm.
- **Unstable Tachycardia** — A rapid heart rate causing symptoms of inadequate perfusion such as hypotension, altered mental status, chest pain, or signs of shock.
- **Ventricular Tachycardia (VT)** — A rapid heart rhythm originating from the ventricles, which can be stable or unstable, and may deteriorate to pulseless VT or ventricular fibrillation.

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