EKG

Nursing Management: Patients With Arrhythmias and Conduction Problems

Copyright Information

  • Copyright © 2024 Wolters Kluwer. All rights reserved.

Learning Objectives

At the end of this lesson, the student will be able to:

  • Describe methods to monitor, diagnose, and treat arrhythmias

  • Analyze elements of an electrocardiogram (ECG) rhythm strip

  • Identify the ECG criteria, causes, and management of arrhythmias

  • Describe the key points of using a defibrillator and the associated waveforms

Primary Characteristics of Cardiac Cells

  • Automaticity: The ability of cardiac cells to generate an electrical impulse spontaneously.

  • Excitability: The ability of cardiac cells to respond to stimuli.

  • Conductivity: The ability of cardiac cells to conduct electrical impulses.

  • Contractility: The ability of cardiac cells to contract in response to electrical stimulation.

Terms to Remember

  • Polarization: The state of a cell when it is at rest, with unequal distribution of ions between the inside and outside of the cell, creating a charge difference.

  • Depolarization: The process by which a cell’s membrane potential becomes less negative or more positive, leading to the generation of an action potential.

  • Repolarization: The return of the cell's membrane potential to its resting state after depolarization.

  • Absolute refractory period: The period during which a cardiac cell cannot respond to another stimulus, regardless of its strength.

  • Relative refractory period: The period following the absolute refractory period during which a stronger-than-normal stimulus may cause depolarization.

PQRST Complex

  • P wave: Represents atrial depolarization.

  • Q wave: First negative deflection after the P wave.

  • R wave: First positive deflection after the Q wave.

  • S wave: Negative deflection following the R wave.

  • T wave: Represents ventricular repolarization.

  • ECG of Normal Sinus Rhythm: Comprehensive visual reference to ECG waveform characteristics.

  • PR Interval: The time from the onset of atrial depolarization to the onset of ventricular depolarization, ranging from 0.12 to 0.20 seconds.

  • PR Segment: The isoelectric line between the end of the P wave and the beginning of the QRS complex.

  • QRS Complex: Represents ventricular depolarization, normally less than 0.10 seconds.

  • ST Segment: The segment following the QRS complex; assesses if repolarization is normal.

  • QT Interval: Time from the start of the Q wave to the end of the T wave; varies with heart rate.

EKG Graph Paper Basics

  • Small box: Represents 0.04 seconds.

  • Large box: Represents 0.20 seconds (5 x 0.04 seconds).

  • 3-second mark: Utilized for measuring heart rate on ECG paper.

Interpreting the Rate

Six-Second Method

  • Locate the three-second markers along the top or bottom of the ECG paper.

  • Count the number of R waves occurring between two three-second markers and multiply by 10 to find the heart rate.

Large-box/300 Method (R-R Interval)

  • Count the number of large boxes between two R waves.

  • Divide 300 by the number of large boxes counted.

Small-box/1500 Method

  • Locate two consecutive R waves.

  • Count the exact number of small boxes between these two R waves.

  • Divide 1500 by the number of small boxes counted.

The Electrocardiogram (ECG/EKG)

  • A noninvasive diagnostic test that records the electrical activity of the heart over time using electrodes placed on the skin.

12 Lead EKG

  • Visual map of lead placements for comprehensive cardiac assessment.

    • RA: Right Arm

    • V₁, V₂, V₃, V₄, V₅, V₆: Precordial leads measuring electrical activity in the horizontal plane.

    • RL, LL: Right Leg, Left Leg.

    • Placement positions represent various anatomical locations crucial for accurate readings.

Normal Sinus Rhythm

  • Rate: 60 to 100 bpm in adults

  • Rhythm: Regular.

  • P wave: Normal and consistent shape, always precedes the QRS complex.

  • PR interval: Consistent and ranges from 0.12 to 0.20 seconds.

  • QRS duration: Less than 0.10 seconds.

Sinus Node Arrhythmias (Dysrhythmias)

  • Definition: A disturbance in impulse discharge from the sinus node resulting in an irregular rhythm.

Types of Sinus Node Arrhythmias

  • Sinus Tachycardia: Discharge occurs too fast.

  • Sinus Bradycardia: Discharge occurs too slow.

  • Sinus Arrest: Fails to discharge impulses.

  • Symptomatic Manifestations: Related to decreased cardiac output and may increase risk of clot formation within the heart chambers.

Sinus Bradycardia

  • Rate: <60 bpm

  • Rhythm: Regular

  • P wave: Present before each QRS, consistent in size and shape

  • PR interval: Normal

  • QRS duration: Normal

Clinical Manifestations

  • Symptoms include dizziness, lightheadedness, fatigue, shortness of breath, chest pain, confusion, and fainting.

Medical and Nursing Management

  • Asymptomatic: No treatment required.

  • Symptomatic:

    • Transcutaneous pacing

    • Administration of atropine

    • Permanent pacing may be necessary.

Sinus Tachycardia

  • Rate: >100 bpm

  • Rhythm: Regular

  • P wave: Normal, consistent in shape, precedes each QRS complex.

  • PR interval and QRS duration: Both normal.

Treatment

  • Identify and treat the underlying cause (physiological or psychological stress, medications, stimulants, drugs).

Abnormal Atrial Rhythms

  • Types include Premature Atrial Contractions (PACs), Atrial Fibrillation (Afib), Atrial Flutter (Aflutter), and Supraventricular Tachycardia (SVT).

Premature Atrial Contraction (PAC)

  • Rate: Depends on underlying rhythm

  • Rhythm: Irregular

  • P wave: Differing size and shape associated with the premature beat compared to SA-generated P waves; PR interval of premature beat >0.12 seconds is less than that of normal sinus.

  • QRS duration: Normal.

Medical and Nursing Management

  • No specific treatment if hemodynamically stable; manage the underlying cause.

Atrial Flutter

  • Rate: Between 220 and 350 bpm

  • Rhythm: Regular (may become irregular with changes in AV conduction)

  • P wave: Flutter waves presenting a “sawtooth” pattern

  • PR interval: Not measurable

  • QRS duration: Normal.

Clinical Manifestations, Assessment & Treatment

  • Symptoms include fatigue, lightheadedness, syncope, chest pain, shortness of breath, hypotension.

  • Treatment may include cardioversion and anticoagulation.

Atrial Fibrillation (AF)

  • Atrial rate: 300 to 400 bpm

  • Rhythm: Irregular

  • P waves: Indistinguishable

  • PR interval: Not measurable

  • QRS duration: Usually normal (<0.12 seconds).

Clinical Manifestations and Assessment

  • Symptoms include shortness of breath, fatigue, palpitations, lightheadedness, and hypotension.

Medical and Nursing Management

  • Cardioversion (electrical or pharmacologic) can be conducted using:

    • Beta blockers

    • Calcium channel blockers

    • Potassium channel blockers

    • Sodium channel blockers

Supraventricular Tachycardia (SVT)

  • Rate: 150–250 bpm (>100 at rest)

  • Rhythm: Regular

  • P waves: Inverted if visible or may occur after the QRS complex

  • PR interval: Not measurable

  • QRS duration: Normal in paroxysmal SVT.

Clinical Manifestations & Management

  • Symptoms include palpitations, chest pain, shortness of breath, dizziness, syncope, and anxiety. Management options include vagal maneuvers, synchronized cardioversion, and pharmacologic treatments.

Junctional Arrhythmias

  • Junction rhythm:

    • Rate: 40 to 60 bpm

    • Rhythm: Regular

    • P wave: If visible, may occur before, during, or after the QRS complex

    • PR interval: If P wave visible, it is <0.12 seconds

    • QRS duration: Normal

Management

  • Management similar to bradycardia protocols.

Ventricular Arrhythmias

  • Types include Bundle Branch Block, Ventricular Tachycardia (VT), Ventricular Fibrillation (VF), and Premature Ventricular Contractions (PVCs).

Abnormal Ventricular Conduction (Bundle Branch Block)

  • Definition: Abnormal conduction delays in right or left bundle branches of the ventricles.

  • QRS complex: Prolonged or widened (>0.12 seconds).

Treatment

  • Address the underlying cause, including ischemic heart disease, hypertension, cardiomyopathy, or electrolyte imbalances.

Ventricular Tachycardia (VT)

  • Rate: 100 to 250 bpm

  • Rhythm: Regular

  • P wave: Usually not visible; if present, it does not associate with QRS (dissociation).

  • PR interval: Not present

  • QRS duration: >0.12 seconds.

Manifestations

  • Symptoms related to decreased cardiac output include hypotension or syncope, pulselessness, and unresponsiveness.

Management

  • Pulseless VT (PVT): Treat like cardiac arrest.

  • Unstable VT with a pulse: Synchronized cardioversion required.

  • Stable VT with pulse: Administer Amiodarone.

  • Torsades de Pointes (Polymorphic VT): Treat with IV magnesium sulfate (1–2 g).

Ventricular Fibrillation (VF)

  • Description: A rapid, disorganized ventricular rhythm with chaotic, irregular rhythm.

  • Rate: Not measurable (occasional >220 bpm)

  • Rhythm: Irregular and chaotic

  • P wave, PR interval, QRS duration: Not visible.

Management

  • Defibrillation is critical.

  • Administer cardiopulmonary resuscitation (CPR) immediately.

  • Activate emergency services.

  • Pharmacologic interventions may include vasoactive medications (e.g., epinephrine) and Amiodarone.

Ventricular Asystole

  • Description: Cardiac standstill characterized by non-measurable rate and rhythm.

  • P wave, PR interval, QRS duration: All absent.

Management

  • Provide high-quality CPR.

  • Follow Advanced Cardiac Life Support (ACLS) protocols, addressing Hs and Ts.

Hs & Ts

  • Elements of reversible causes in cardiac arrest include:

    • Hypovolemia

    • Hypoxia

    • Hydrogen ions (acidosis)

    • Hypo/hyperkalemia

    • Hypothermia

    • Tamponade (cardiac)

    • Tension pneumothorax

    • Toxins

    • Thrombosis (pulmonary and coronary)

Conduction Abnormalities

  • Heart Blocks:

    • First-degree Atrioventricular (AV) Block

    • Second-degree AV Block:

    • Type I, Mobitz I (Wenckebach)

    • Type II, Mobitz II

    • Third-degree AV block (complete heart block)

First-degree Atrioventricular Block

  • Rate: 60-100 bpm depending on underlying rhythm

  • Rhythm: Regular

  • P wave: Present before each QRS, consistent in size and shape

  • PR interval: >0.20 seconds

  • QRS duration: Normal

Second-degree Atrioventricular Block, Type I (Wenckebach)

  • Atrial rate > ventricular rate.

  • Rhythm: Atrial rhythm regular; ventricular rhythm irregular.

  • P wave: Size and shape normal.

  • PR interval: Increases progressively until a QRS complex is dropped.

  • QRS duration: Normal.

Second-degree Atrioventricular Block, Type II

  • Atrial rate > ventricular rate.

  • Rhythm: Atrial rhythm regular (constant PP interval); ventricular rhythm is irregular.

  • P wave: Normal.

  • PR interval: In conducted beats, constant with no progressive prolongation.

  • Dropped QRS: Noted without changes in PR intervals.

Third-degree Atrioventricular Block

  • Atrial rate: 60-100 bpm, Ventricular rate: 20 to 40 bpm.

  • Rhythms are independent: Atria and ventricles do not coordinate.

  • P wave: Constant with more P waves than QRS complexes.

  • PR interval: Absent; no relationship between P wave and R wave.

  • QRS duration: Normal or wide, unrelated to P wave.

Review Questions

Question 29

  • Which of the following arrhythmias creates the most significant risk for cerebrovascular accident?

    • Sinus tachycardia

    • Sinus bradycardia

    • Atrial fibrillation

    • Premature atrial complex

Question 41

  • A patient has been brought to the emergency department in ventricular asystole. The priority for this patient’s care is:

    • Application of supplementary oxygen by face mask

    • Administration of corticosteroids and bronchodilators

    • Cardiopulmonary resuscitation

    • Chest auscultation

Question 47

  • A patient presents with dizziness and a heart rate of 38 bpm. The EKG shows regular P waves with a constant rate, but the QRS complexes occur independently at a slower, regular ventricular rate. What rhythm is this?

    • Second-degree AV block type I (Wenckebach)

    • Second-degree AV block type II

    • Third-degree (complete) heart block

    • Sinus bradycardia

Question 48

  • A patient is in the ICU with sepsis. The monitor shows a narrow-complex tachycardia at 180 bpm with no visible P waves. Carotid massage has no effect. Which rhythm is most likely?

    • Atrial fibrillation with rapid ventricular response

    • Atrial flutter with 2:1 conduction

    • Supraventricular tachycardia (SVT)

    • Ventricular tachycardia

Question 49

  • An elderly patient suddenly becomes unresponsive. The EKG shows a chaotic baseline with no identifiable P waves, QRS complexes, or T waves. What is the nurse’s priority action?

    • Start transcutaneous pacing

    • Begin CPR immediately

    • Administer amiodarone IV

    • Prepare for synchronized cardioversion