Electrocardiography Principles Quiz
46 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

If a wavefront of depolarization moves directly away from a recording electrode, what will be the recorded ECG deflection?

  • A large positive deflection
  • A large negative deflection
  • No deflection (correct)
  • A small deflection

Which of the following statements accurately describes the relationship between the orientation of the wavefront of depolarization and the recorded ECG deflection?

  • A wavefront moving parallel to the lead axis will result in the smallest deflection.
  • A wavefront moving perpendicular to the lead axis will result in the largest deflection.
  • A wavefront moving parallel to the lead axis will result in the largest deflection. (correct)
  • The size of the deflection is independent of the wavefront orientation.

The normal activation sequence of the heart begins at the _______ and then progresses through the _______ to the ventricles.

  • SA node; AV node (correct)
  • His-Purkinje system; AV node
  • Ventricular muscle; atria
  • AV node; SA node

What is the significance of the negative charges moving toward the positive electrode in the context of ECG recordings?

<p>It results in a negative deflection on the ECG. (B)</p> Signup and view all the answers

Consider a wavefront of depolarization traveling directly towards the recording electrode (parallel to the lead axis). If the electrode is negative and the other electrode is positive, what will be the direction of ECG deflection?

<p>Positive (A)</p> Signup and view all the answers

What is the unit of measurement on the y-axis of an electrocardiogram (ECG)?

<p>Millivolts (A)</p> Signup and view all the answers

What type of cellular event is recorded as an upward deflection on the ECG?

<p>Depolarization of the atria (D)</p> Signup and view all the answers

What is the correct order of cardiac activation, starting with the pacemaker?

<p>Sinoatrial node, atrioventricular node, bundle of His, Purkinje fibers (A)</p> Signup and view all the answers

Which part of the cardiac conduction system is characterized by the slowest conduction velocity?

<p>Atrioventricular node (D)</p> Signup and view all the answers

Which of the following is NOT a piece of information that can be obtained from an ECG?

<p>Strength of cardiac contractions (A)</p> Signup and view all the answers

What is the purpose of recording a base-apex ECG in horses?

<p>To identify potential abnormalities in the heart rhythm (A)</p> Signup and view all the answers

What cellular event does the QRS complex on an ECG represent?

<p>Depolarization of the ventricles (B)</p> Signup and view all the answers

Which of the following statements regarding cardiac tissue is FALSE?

<p>Repolarization of cardiac myocytes results in a negative charge inside the cell (A)</p> Signup and view all the answers

Which of the following structures has the fastest conduction velocity?

<p>His-Purkinje system (D)</p> Signup and view all the answers

What is the normal pacemaker rate of the SA node?

<p>60-250 impulses/min (B)</p> Signup and view all the answers

Which of the following is a function of the AV node?

<p>Delaying the electrical impulse before it reaches the ventricles (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of the His-Purkinje system?

<p>Located in the atrial muscle (C)</p> Signup and view all the answers

Which of the following is a true statement about terminal Purkinje fibers?

<p>They are resistant to the effects of hyperkalemia. (D)</p> Signup and view all the answers

In the standard lead II electrocardiogram, which electrode is placed on the right forelimb?

<p>White (C)</p> Signup and view all the answers

What is the orientation of the lead axis in the base-apex lead?

<p>Cranial-to-caudal, right-to-left (B)</p> Signup and view all the answers

What does the P wave on an electrocardiogram represent?

<p>Atrial depolarization (D)</p> Signup and view all the answers

Which of the following accurately describes the PR interval?

<p>Includes depolarization of the atria, AV node and His-Bundle (C)</p> Signup and view all the answers

What is the normal QRS complex duration in dogs?

<p>Less than 0.06 seconds (B)</p> Signup and view all the answers

Which of the following is the key difference between the QRS complex in small animals and large animals?

<p>The QRS complex in small animals is usually negatively deflected, while the QRS complex in large animals is often positively deflected. (A)</p> Signup and view all the answers

What does the ST segment on an electrocardiogram represent?

<p>Isoelectric period between ventricular depolarization and repolarization (B)</p> Signup and view all the answers

Which of the following is a true statement about the T wave?

<p>It represents ventricular repolarization and may be negative, positive, or biphasic. (A)</p> Signup and view all the answers

What is the purpose of using a grounding electrode in electrocardiography?

<p>To provide a stable reference point for the electrical signal. (D)</p> Signup and view all the answers

When is the use of a base-apex lead particularly advantageous?

<p>When assessing the electrical activity of the ventricles in large animals. (C)</p> Signup and view all the answers

What occurs when a resting myocyte is stimulated?

<p>The cell undergoes depolarization. (A)</p> Signup and view all the answers

What is the primary function of the atrial internodal tracts?

<p>To conduct the electrical impulse from the SA node to the AV node. (A)</p> Signup and view all the answers

How does depolarization spread from one heart cell to another?

<p>By stimulating adjacent cells to depolarize. (C)</p> Signup and view all the answers

What is the significance of the PR interval being prolonged?

<p>It may indicate delayed conduction through the AV node. (C)</p> Signup and view all the answers

What is necessary for the depolarization process to occur repeatedly?

<p>Cells must repolarize. (B)</p> Signup and view all the answers

When measuring the electrical field with ECG electrodes, where should the negative electrode be placed in relation to the wave of depolarization?

<p>Adjacent to the wave of depolarization. (D)</p> Signup and view all the answers

What effect does a wavefront of negative extracellular charges moving toward the positive electrode have on the ECG reading?

<p>It causes an upward deflection. (C)</p> Signup and view all the answers

What type of wave of electrical activity is primarily recorded by the electrocardiogram?

<p>Depolarization waves. (A)</p> Signup and view all the answers

In the context of the electrocardiogram, what does the positive portion of the electrical field represent?

<p>The wave of depolarization. (D)</p> Signup and view all the answers

What role do extracellular currents play in the depolarization process as measured by an electrocardiogram?

<p>They assist in the measurement of electrical activity. (B)</p> Signup and view all the answers

What does a bifid (notched) P wave indicate in horses?

<p>It is a normal condition. (A)</p> Signup and view all the answers

Which of the following best describes the pattern of wave depolarization in the cardiac cycle?

<p>The wave of depolarization moves from cranial to caudal. (C)</p> Signup and view all the answers

In horses, what represents the negative electrode during an ECG?

<p>Over the right jugular furrow. (D)</p> Signup and view all the answers

What characterizes the QRS complex in healthy horses?

<p>It presents a normal sinus rhythm. (B)</p> Signup and view all the answers

What is a misleading characteristic of normal sinus rhythms in dairy cows?

<p>Negative QRS complexes are common. (A)</p> Signup and view all the answers

During ECG, what represents the normal electrical activity of the heart?

<p>Consecutive normal P, QRS, and T waves. (C)</p> Signup and view all the answers

What is NOT true regarding ventricular repolarization?

<p>It initiates the cardiac cycle. (C)</p> Signup and view all the answers

What is the correct sequence of electrical activity in a normal cardiac cycle?

<p>Atrial depolarization, ventricular depolarization, ventricular repolarization. (B)</p> Signup and view all the answers

Flashcards

Electrocardiogram (ECG)

A recording of the heart's electrical activity as seen from the surface of the body.

Wave/Complex in ECG

An upward or downward deflection on the ECG representing a change in electrical potential.

Depolarization

The moment when a heart cell's inside becomes more positive than the outside.

Repolarization

The moment when a heart cell's inside becomes more negative than the outside again.

Signup and view all the flashcards

Voltage (mV) Axis

The vertical axis on an ECG graph, representing electrical voltage.

Signup and view all the flashcards

Time (sec) Axis

The horizontal axis on an ECG graph, representing time.

Signup and view all the flashcards

Limitations of ECG

The ECG can be used to assess heart rhythm and conduction problems, but it doesn't directly measure the force of the heart's contractions.

Signup and view all the flashcards

ECG and Heart Chamber Size

The ECG is particularly useful in small animals to assess the relative sizes of heart chambers.

Signup and view all the flashcards

What is depolarization wavefront?

The movement of electrical charges through the heart muscle, usually from negative to positive, creates a wavefront of depolarization.

Signup and view all the flashcards

What is the role of the SA node?

The area of the heart that initiates the electrical impulse and acts as the heart's natural pacemaker, setting the rate of the heartbeat.

Signup and view all the flashcards

How does wavefront orientation affect ECG deflection?

The direction of the wavefront of depolarization relative to the recording lead axis determines the size and direction of the deflection on an ECG.

Signup and view all the flashcards

What is the normal activation sequence of the heart?

The normal activation sequence in the heart follows a specific pathway, starting with the SA node, through the atria, AV Node, His-Purkinje system, and finally to the ventricles.

Signup and view all the flashcards

What is the role of the recording lead axis in an ECG?

The orientation of the recording lead axis determines the direction of the electrical signal being detected in the ECG.

Signup and view all the flashcards

Wave of Depolarization

The spread of depolarization from one cell to another, creating a wave-like pattern.

Signup and view all the flashcards

Wavefront Direction

The direction of the wave of depolarization relative to the positive electrode of the ECG.

Signup and view all the flashcards

Upward Deflection on the ECG

An upward deflection on the ECG trace occurs when the wavefront of negative charges moves toward the positive electrode.

Signup and view all the flashcards

Electrical Field of the Heart

The electrical field created by the heart is measured by the ECG, which detects the spread of depolarization.

Signup and view all the flashcards

Repolarization is Essential

The heart muscle cells must repolarize to allow the cycle of depolarization and repolarization to repeat, enabling continuous heart function.

Signup and view all the flashcards

Cardiac Depolarization

The process of electrical activation in the heart that spreads from the atria to the ventricles.

Signup and view all the flashcards

Ventricular Depolarization

The electrical activity in the heart that starts in the atria and spreads to the ventricles.

Signup and view all the flashcards

Ventricular Repolarization

The process of the heart returning to its resting electrical state after depolarization.

Signup and view all the flashcards

Atrial Depolarization

The electrical signal originating from the atria that triggers the atria to contract.

Signup and view all the flashcards

Normal Sinus Rhythm

A normal heart rhythm originating from the sinoatrial node (pacemaker of the heart).

Signup and view all the flashcards

Bifid P Waves

A normal heart rhythm found in horses, indicated by a notched P wave.

Signup and view all the flashcards

Negative QRS Complexes

A normal feature in horses and cattle, where the QRS complex appears negative.

Signup and view all the flashcards

Base-Apex Lead

An ECG lead placement where the negative electrode is placed over the right jugular furrow and the positive electrode over the left cardiac apex beat.

Signup and view all the flashcards

SA node pacemaker rate

The natural, spontaneous rate of the sinoatrial (SA) node, which is the primary pacemaker of the heart. It is usually between 60-250 impulses per minute in healthy animals.

Signup and view all the flashcards

Conduction Velocity

The speed at which an electrical impulse travels through cardiac tissue. Important Note: Faster conduction velocity doesn't necessarily mean faster heart rate.

Signup and view all the flashcards

Normal activation sequence

The specific sequence in which electrical impulses travel through the heart, starting at the SA node and culminating in ventricular contraction.

Signup and view all the flashcards

Pacemaker

A specialized group of cells that can initiate their own electrical impulses, allowing the heart to beat even without external stimulation from the nervous system.

Signup and view all the flashcards

Pacemaker Rate

The rate at which a tissue depolarises. The SA node is the fastest and dominant pacemaker, but other tissues can take over if it fails.

Signup and view all the flashcards

AV node

A specialized region of the heart that slows down the transmission of electrical impulses from the atria to the ventricles. This delay allows the atria to fully contract before the ventricles are stimulated.

Signup and view all the flashcards

His-Purkinje system

A specialized network of fibers that rapidly conducts electrical impulses from the AV node to the ventricular muscle, allowing for coordinated and efficient ventricular contraction.

Signup and view all the flashcards

Atrial Muscle

Cardiac tissue located in the walls of the atria, responsible for atrial contractions, and is relatively resistant to high potassium levels compared to other tissues.

Signup and view all the flashcards

Bundle of His/Bundle Branches

A special structure in the heart that branches into the right and left bundle branches, responsible for quickly transmitting the electrical impulse to the ventricular muscle.

Signup and view all the flashcards

Terminal Purkinje Fibers

The very end of the conducting system that penetrates deeply into ventricular muscle, delivering electrical impulses for coordinated contraction.

Signup and view all the flashcards

Electrode Placement

Electrodes placed on specific areas of the animal's body to record electrical signals from the heart.

Signup and view all the flashcards

Lead

A specific combination of electrodes used to record the heart's electrical activity. Each lead records signals from a specific orientation within the heart.

Signup and view all the flashcards

Lead II

The most commonly used lead in clinical settings. It measures the electrical activity between the right forelimb (negative electrode) and the left hindlimb (positive electrode), resulting in a cranial to caudal and right to left orientation.

Signup and view all the flashcards

Base-to-Apex lead

A specific arrangement of electrodes designed to record the electrical activity from the base of the heart to its apex. It uses a different orientation than other standard leads.

Signup and view all the flashcards

P-wave

A positive deflection in the electrocardiogram (ECG) representing normal atrial depolarization. It is often biphasic (M-shaped) in horses.

Signup and view all the flashcards

PR Interval

The portion of the ECG waveform that includes the atrial depolarization, AV node conduction, and His-Bundle depolarization. It reflects the time it takes for the electrical signal to travel through the AV node and reaches the ventricles.

Signup and view all the flashcards

Study Notes

Electrocardiography Principles

  • Electrocardiogram (ECG or EKG) records the heart's electrical activity from the body surface.
  • ECG records extracellular signals caused by the movement of depolarization/repolarization waves through cardiac myocytes.
  • The graph displays voltage (mV, y-axis) over time (seconds, x-axis).
  • Changes in voltage are recorded as waves/complexes (P, QRS, T).

Learning Objectives

  • Label the x- and y-axes of an ECG.
  • Describe cell surface events associated with upward deflections on an ECG.
  • List the normal cardiac activation sequence from memory.
  • For each component of the cardiac conduction system, describe relative conduction velocity and expected pacemaker activity.
  • Describe the method for recording a 6-lead ECG in a dog and a base-apex ECG in a horse.
  • Label individual waves on a normal ECG and explain the cellular events they represent.

Physiology Review: Basic Cardiac Electrophysiology

  • Cardiac tissue is excitable.
  • At rest, cardiac myocytes are polarized (negatively charged inside versus outside the membrane).
  • When stimulated, resting myocytes depolarize (membrane polarity reverses).
  • Depolarization spreads as a wave, triggering adjacent cells to depolarize.
  • Extracellular currents associated with the depolarization wave are detected by the ECG.
  • Cells must repolarize for the cycle to repeat.

Electrocardiography - (re)introduction

  • ECG evaluation provides insights into heart rate, rhythm disturbances, conduction abnormalities, and relative chamber sizes (in smaller animals).
  • ECG does not measure mechanical activity (contraction strength, etc).

Physiology Review: Normal Cardiac Conduction System

  • The heart's electrical activity originates from the sinoatrial (SA) node (pacemaker).
  • The sequence: SA node → internodal tracts → atrioventricular (AV) node → Bundle of His → right and left bundle branches → Purkinje fibers → ventricular muscle.
  • Conduction velocities and pacemaker rates vary throughout these components.
  • The SA node has a rate of 60-250 bpm.
  • AV node has a rate of 40-60 bpm.
  • His-Purkinje system has a rate of 20-40 bpm.

Physiology Review: Normal Cardiac Conduction System (Special Notes)

  • Atrial internodal tracts transmit impulses rapidly between the SA and AV nodes, relatively resistant to hyperkalemia.
  • The Bundle of His divides into the right and left bundle branches, which rapidly conduct impulses to terminal Purkinje fibers.
  • Terminal Purkinje fibers rapidly conduct impulses throughout the endocardium of the ventricles.

Method for Recording a 6-Lead Surface ECG in Small Animals

  • Patient in right lateral recumbency.
  • Limbs parallel to one another, perpendicular to trunk.
  • Calm environment, non-conducting surface to minimize artifacts.
  • Use white/black electrodes on forelimbs and red/green electrodes on hindlimbs.
  • Avoid contact between electrodes and trunk, and avoid electrode contact with each other.

Method for Recording a Surface "Base-to-Apex" ECG in Horses and Ruminants

  • No universal lead system in large animals.
  • Set machine to record in lead I (RA to LA).
  • Place a white electrode on the right jugular furrow, a black electrode on the cardiac left apex.
  • Lead axis is cranial-to-caudal, right-to-left.

The Normal (Lead II) ECG Tracing

  • Depolarization is represented by upward deflections in Lead II.
  • Depolarization proceeds from the right atrium to the left ventricle.
  • Depolarized tissue is blue.
  • Pink arrow signifies the direction of the depolarization wave.

Electrical Correlates of ECG Waves/Intervals

  • P wave: Atrial depolarization, positive in lead II, frequently bifid (M-shaped) in horses.
  • PR (PQ) interval: Atrial, AV node, and Bundle of His depolarization, <0.13 seconds (dog), < 0.09 seconds (cat).
  • QRS complex: Ventricular depolarization, generally upright and narrow in small animals, <0.06 seconds (dog), <0.04 seconds (cat).
  • ST segment: Isoelectric line connecting S and T waves, indicating ventricular cell depolarization is complete and no current flows in lead II.
  • T wave: Ventricular repolarization, a complex process, important for function of the heart.

Normal Base-Apex ECG in Horses/Ruminants

  • Bifid (notched) P waves are normal in horses.
  • Negative QRS complexes are normal in horses and cattle.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Principles of Electrocardiography PDF

Description

Test your knowledge of electrocardiography principles with this quiz! It covers the basics of ECG interpretation, including the labeling of the x- and y-axes, the cardiac activation sequence, and individual wave representation. Additionally, you will explore methods for recording ECGs in different animals.

More Like This

Electrocardiography Quiz
24 questions

Electrocardiography Quiz

MomentousPond avatar
MomentousPond
ECG Interpretation: Atrial and Ventricular Enlargement
14 questions

ECG Interpretation: Atrial and Ventricular Enlargement

HeavenlyPiccoloTrumpet avatar
HeavenlyPiccoloTrumpet
ECG Interpretation Quiz
32 questions

ECG Interpretation Quiz

FavoriteIodine avatar
FavoriteIodine
ECG Interpretation Basics
23 questions

ECG Interpretation Basics

IllustriousTabla avatar
IllustriousTabla
Use Quizgecko on...
Browser
Open
Browser
Browser