Exam 2

Responsibility of an EKG technician

Is to generate a correct and readable EKG tracing. This Learning Objective is an overview of situations that might require changes to the usual EKG procedures in order to achieve that goal.

Artifact

• interference or distortion that appears on an EKG tracing - may be caused by

  • Environmental factors

  • Defective equipment

  • Patient conditions

These patient conditions/situations may require changes to standard EKG testing:

• Pregnancy beyond the sixth month

• Limb amputation or injury

• Presence of scar tissue/broken skin

• Situations in which the patient’s age or health condition affects the position of the heart

EKG procedures may also have to be adapted for patients under Transmission-Based Precautions:

• Disposable lead wires may be used

• Testing may take place in a specially ventilated room

• There may be different or additional procedures required for disinfection of EKG equipment after testing

• EKG technicians should always follow any special infection prevention measures noted in the patient’s record or required by the facility

somatic tremor

EKG artifact usually caused by patient tremors or shivering.

wandering baseline

EKG artifact in which the normally flat baseline moves up and down across the tracing.

abrade

in electrocardiography, to lightly scrub the outer layer of the skin to remove debris that can interfere with electrode contact.

electrical interference

in electrocardiography, a type of artifact caused by the presence of other appliances or equipment in the area surrounding the EKG machine

broken recording

EKG artifact that occurs when the signal is compromised by frayed or faulty lead wires

Remember these points about addressing somatic tremor artifact:

• Patients with Parkinson’s disease or other medical problems may need to be positioned with their hands palms-up under their buttocks to reduce tremors

• Placing limb electrodes on the torso may reduce artifact in patients with tremors

• Blankets can help stop tremors in patients who are cold, as can increasing the room temperature

• Pillows may be used to make a patient more comfortable and less likely to tremble or move

• Anxious or nervous patients should be reassured and given time to relax

Remember these points about addressing wandering baseline artifact:

• Movement of muscle groups like those used for breathing can cause wandering baseline, so it can be helpful to remind patients to remain still and breathe normally

• Placing the electrodes for the limb leads on the wrists and ankles can help eliminate wandering baseline caused by breathing irregularities

• Loose electrodes or poor electrode contact are common causes of wandering baseline. The following skin preparation techniques can improve electrode contact:

  • Remove sweat or moisture with towel, paper towel, or gauze pads.

  • Remove skin oil or substances like lotion with soap and water.

  • Gently abrade the skin using dry gauze or a special skin abrading product.

  • Remove body hair as needed to increase contact between skin and electrodes (use only medical clippers)

Remember these points about addressing electrical interference artifact:

• Turn off other electrical appliances in the area

• Plug the EKG machine in to a different outlet

• If an extension cord is being used, discontinue use of extension cord

• Make sure the machine is properly grounded (three prongs on the cord, plugged in to a three-prong outlet)

• Turn off fluorescent lights

• Mobile phones can cause electrical interference, so any phones in the room should be removed from the immediate testing area

Making a habit of double-checking all of the following will help ensure accurate, artifact-free EKG tracings:

• Fresh, in-date electrodes adhering properly to the patient’s skin

• Electrodes in the correct locations and attached to the correct lead wires

• Lead wires properly connected to the electrodes and to the machine

• Lead wires not frayed or damaged in any way

dextrocardia

a rare heart condition that causes the heart to develop pointing to the right side of the chest instead of the left side.

Remember these points about dextrocardia:

• It is a rare heart condition that causes the heart to develop pointing to the right side of the chest rather than to the left side

• The patient is usually aware of this condition or it is noted in the chart

• If the electrodes are placed in the standard, left-sided positions, the EKG will not be accurate

Remember these points about electrode placement for patients with limb amputation or injury:

• A patient who has had a limb amputation or who has an injury that limits access to a limb requires adapted electrode placement

• The key for adaptations is that the electrode for the corresponding, unaffected limb should be placed in a mirror position

Remember these points about electrode placement for patients who have undergone mastectomy or who have scars on/injury to the chest wall

• Avoid placing electrodes on scar tissue, which can be fragile and may be injured when the electrode is removed

• Electrodes should be placed as close as possible to the standard locations

Remember these points about electrode placement for patients with large breasts:

• Move breast tissue away from the electrode site as much as possible so the electrodes are placed on the chest wall

• Explain the process to the patient and get the patient’s consent before making any contact

• The patient can lift her own breast tissue or the technician can use the back of a hand to move the tissue

• Electrodes should be placed as closely as possible to the standard position and should not be placed on top of breast tissue

Electrode placement for pediatric patients differs from placement for adult patients:

• Children under two years of age require right-sided placement

• Children between two and twelve require adapted placement as shown in the next slide

Remember these points about posterior EKGs:

• Sometimes a doctor will ask to have an EKG repeated using posterior leads

• This can help to diagnose a particular type of heart attack (inferior wall myocardial infarction)

Patient health conditions or circumstances might require changes to positioning:

• Respiratory or heart problems might make it difficult for patients to tolerate supine position. Semi-Folwer’s position will likely be more comfortable for these patients.

• Patients who are six months or more pregnant should not be placed in the supine position. Pillows can be used to tilt these patients to the left, taking pressure off the vena cava.

Cardiac output in an essential measure of the function of the heart:

• Cardiac output is the amount of blood, measured in liters, that the heart pumps each minute

• Cardiac output per minute = amount of blood pumped with each heartbeat (stroke volume) multiplied by the number of heartbeats per minute

• If cardiac output is low, the patient’s health will suffer

• Low output can be caused by electrical and mechanical problems

These requirements have to be met in order for the heart to pump blood through the body:

• Electrical system of the heart working properly

• Mechanical components (muscle and valves) healthy

• Enough blood to pump through an intact vascular system

cardiac conduction system

the pathway of electrical impulses that controls the heart’s pumping action.

intrinsic rate

the normal firing rate (expressed in beats per minute) associated with a part of the heart’s electrical conduction system.

sinoatrial node

part of the electrical conduction system of the heart, located in the upper part of the right atrium and acting as the primary pacemaker of the heart, with an intrinsic rate of 60–100 BPM; also called the SA node or sinus node

pacemaker

something that regulates the heart’s contractions; natural pacemakers are part of the cardiac conduction system, with the sinoatrial (SA) node acting as the primary pacemaker when the heart is functioning normally. An artificial pacemaker is a battery-powered device that creates electrical impulses to stimulate the heart

atrioventricular node

part of the electrical conduction system of the heart, located at the bottom of the right atrium, behind the tricuspid valve, with an intrinsic rate of 40–50 BPM.

atrioventricular (AV) junction

part of the electrical conduction system of the heart, located between the AV node and the bundle of His.

bundle of His

part of the electrical conduction system of the heart, located in the upper part of the interventricular septum, with an intrinsic rate of 40–50 BPM; also called AV bundle.

bundle branches

part of the electrical conduction system of the heart; they divide from the bundle of His and carry the electrical impulse to the walls of the ventricles.

Purkinje fibers

part of the electrical conduction system of the heart; they divide from the bundle branches and have an intrinsic rate of 20–40 BPM.

irritable

in reference to the cardiac conduction system, more likely to initiate an electrical impulse at the wrong time or in the wrong location.

Remember these points about the cardiac conduction system:

• The SA node is the primary pacemaker of the heart.

• Other areas of the conduction system can initiate an impulse if it fails.

• Lack of oxygen or other problems in the heart could cause another area to initiate an impulse, as well

isoelectric line

on an EKG tracing, the straight line between upward and downward movements (also sometimes called the baseline)

wave

on an EKG tracing, movement upward or downward from the isoelectric line; a positive wave moves upward and a negative wave moves downward.

segment

on an EKG tracing, the isoelectric area between two waves.

interval

on an EKG tracing, a wave and a segment taken together.

complex

several EKG waves considered together.

morphology

the shape and direction of waves, complexes, and segments on an EKG tracing.

normal sinus rhythm

cardiac rhythm produced when the electrical system of the heart is functioning normally.

P wave

in normal sinus rhythm, the first positive deflection (upward movement) seen on an EKG tracing; corresponds to the contraction of the atria.

QRS complex

an EKG complex that includes the Q, R, and S waves and corresponds to the contraction of the ventricles; appearance in EKG tracings can vary widely.

T wave

an EKG wave that follows the QRS complex and corresponds to the relaxation of the ventricles.

PR interval

on an EKG tracing, the interval from the beginning of the P wave to the beginning of the QRS complex.

QRS interval

the length of time associated with a complete QRS complex on an EKG tracing; normal measurement is less than 0.12 seconds

R-R interval

on an EKG tracing, the interval between the R wave of one complex and the R wave of the next complex

ST segment

on an EKG tracing, the segment between the J point (the end of QRS) to the beginning of the T wave

EKG Graph Paper

heart rhythm

the overall pattern of the heartbeat.

heart rate

the speed at which the heart is beating.

These six steps are required to analyze an EKG tracing

1. Determine heart rate (in BPM)

2. Examine the rhythm for regularity (clear pattern or lack of pattern)

3. Note presence or absence of P wave before each QRS, and note qualities of P wave

4. Measure length of PR interval

5. Measure length of QRS interval

6. Identify (name) the rhythm

six-second method

method used to determine heart rate from an EKG tracing that involves identifying a six-second section of the EKG and counting the number of QRS complexes in that section, then multiplying by 10.

large block method

method used to determine heart rate from an EKG tracing that involves counting the numbers of large blocks between two consecutive R waves and dividing that number into 300, which is the number of large blocks in a one-minute EKG strip; also called the 300 method

small block method

method used to determine heart rate from an EKG tracing that involves counting the small blocks between two consecutive R waves and dividing that number into 1500, which is the number of small blocks representing the passage of one minute; also called the 1500 method.

Remember these points about the six-second method

• Involves counting the number of complete QRS complexes in a six-second section of EKG tracing and multiplying that number by 10 to determine rate

• It is the least precise method of determining heart rate

• It is the only method that can be used with irregular rhythms

Remember these points about the large block method:

• Involves counting the large blocks between two consecutive R waves, then referring to a chart for the corresponding heart rate

• Can also be used without the chart, by dividing the number of large blocks between R waves into 300

• Sometimes called the 300 method

Remember these points about the small block method:

• Involves counting the small blocks between two consecutive R waves and dividing 1500 by that number

• 1500 is used because there are 1500 small blocks in a one-minute EKG strip

regular rhythm

general category of heart rhythm in which QRS complexes occur in a pattern that looks the same each time and repeats with consistent timing (for example, every 0.8 seconds).

irregular rhythm

general category of heart rhythm in which QRS complexes may look alike or different from each other, and do not repeat with consistent timing

regularly irregular rhythm

general category of heart rhythm in which QRS complexes may or may not look alike but are irregular in a clear, repeating pattern

calipers

a tool with adjustable points, used to measure intervals on EKG tracings.

Remember these points about measuring the PR interval:

• It is measured from the beginning of the P wave (where it leaves the isoelectric line) to the beginning of the QRS complex

• It can be measured using calipers or a scrap of paper and a pen or pencil

• Normal range for the PR interval is 0.12-0.20 seconds

Remember these points about measuring the QRS complex:

• Measurement is taken from the point where the first wave of the complex leaves the isoelectric line to the point where the last wave begins to flatten out

• Not all QRS complexes show all of these waves, so it can take practice to perfect finding these measurements

• Calipers or paper may be used, as with the PR interval measurements

• Normal range for the QRS duration is less than 0.12 seconds

• Values between 0.10 and 0.12 may be considered slightly prolonged, but not abnormal

escape beat

a heartbeat created when a part of the heart’s electrical conduction system other than the SA node initiates the electrical impulse that causes the heart to beat

escape rhythm

a rhythm in which a part of the heart’s electrical conduction system other than the SA node initiates all electrical impulses that cause the heart to beat (i.e., acts as the heart’s primary pacemaker)

ectopic focus

a situation in which an irritable area in the cardiac conduction system begins to generate an impulse even though the SA node may be working normally

dysrhythmia

difficult or abnormal heart rhythm; includes rhythms that are too fast, too slow, or originate in an area of the heart other than the SA node; sometimes commonly called arrhythmia

sinus rhythm

a cardiac rhythm originating in the sinus (SA) node.

atrial rhythm

a cardiac rhythm originating in the atria instead of the SA node.

junctional rhythm

a cardiac rhythm originating in the cells near the bundle of His or in the area of the AV junction rather than in the SA node.

ventricular rhythm

a cardiac rhythm originating in the ventricles rather than in the SA node; marked on an EKG tracing by a widened QRS complex

heart block

a type of cardiac rhythm caused when the AV node or AV bundle delays the electrical impulse from the SA node too long; also called AV block.

underlying rhythm

the basic rhythm of a patient’s heart, separate from any abnormal beats or complexes

Organization of the Cardiac Conduction System

These are ways in which abnormal beats or rhythms may occur:

• If the SA node fails to generate an impulse and another area generates it, this creates a late beat called an escape beat

• When this happens regularly it is called an escape rhythm

• Irritable sites in the heart may generate electrical impulses, even when the SA node is working normally

• This is known as an ectopic focus (ectopic pacemaker)

Remember these points about dysrhythmias:

• A rhythm might be too fast, too slow, or originate in a part of the heart other than the SA node

• Five areas in the heart can generate a rhythm and a rhythm is named for the area where it originates

• Sinus rhythms begin in the sinoatrial node

• Atrial rhythms originate in the atria

• Junctional rhythms originate in the AV junction

• Ventricular rhythms originate in the ventricles

• Heart blocks (AV blocks) are caused by problems in the conduction of electrical impulses between the atria and the ventricles

sinus tachycardia

a fast sinus rhythm with normal characteristics but with a rate of 100–160 BPM

• Can be caused by medications, stress, or the body’s need for additional oxygen

• Fever, exercise, fear, and low blood volume can also be causes

• Can be especially dangerous for patients with a history of coronary artery disease

• Treatment depends on the cause

sinus bradycardia

a slow sinus rhythm with normal characteristics but with a rate below 60 BPM

• Dizziness

• Weakness

• Syncope (fainting)

• Changes in mental status/consciousness

• Chest pain

• Shortness of breath

• Clammy skin

• Low blood pressure

sinus arrhythmia

a sinus rhythm in which all characteristics are normal except for rhythm regularity; R-R intervals are irregular and usually vary with the patient’s breathing

• Occurs naturally in some children and adults

• Rarely requires treatment

• If the heart rate slows so dramatically that it causes problems with circulation or cardiac output a medication may be prescribed

sinus arrest

a sinus rhythm resulting when the SA node does not initiate an impulse, causing pauses in the heart’s electrical activity; similar to sinoatrial block but with a greater time between complexes. Also called sinus pause

• Can be caused by SA node damage, medications, or increased vagal tone

• The vagus nerve, which is part of the parasympathetic nervous system, controls vagal tone.

• When the vagus nerve is stimulated the heart rate may slow.

• Patients who are asymptomatic may not require treatment.

• Medication may be prescribed for symptomatic patients

symptomatic

experiencing symptoms

asymptomatic

not experiencing symptoms

premature atrial complex

an atrial rhythm featuring obvious premature beats; other aspects of the rhythm are often normal

wandering atrial pacemaker

an atrial rhythm that occurs when impulses arise from multiple areas, including the atria, the AV node, and the SA node; also called multiformed atrial rhythm

atrial tachycardia

a fast atrial rhythm caused by irritability in the atria, with a rate of 160–250 BPM

multifocal atrial tachycardia

a rhythm related to wandering atrial pacemaker, but with a ventricular rate greater than 100 BPM

supraventricular tachycardia

can be a general term for all tachycardias (fast rhythms) that begin with impulses generated above the ventricles, or for a specific dysrhythmia marked by a very fast rate, P waves that are difficult or impossible to distinguish, and narrow QRS complexes; also called narrow complex tachycardia

atrial fibrillation

a common dysrhythmia that occurs when multiple irritable sites fire in the atria; considered controlled if the ventricular rate is under 100 BPM and uncontrolled if the ventricular rate is above 100 BPM

rapid ventricular response

contractions of the ventricles in an atrial fibrillation rhythm at a rate of 100 BPM or greater

atrial flutter

an atrial rhythm that occurs when an irritable site in the atria fires at a very rapid rate

F-waves

short for flutter waves; waves displayed on the EKG tracing of a patient with atrial flutter representing the distortion of the P wave as the AV node blocks impulses that exceed 180 per minute; also called sawtooth or picket fence waves

atrial rate

the rate at which the atria contract (in normal rhythms, it is the same as the ventricular rate).

ventricular rate

the rate at which the ventricles are contracting; in normal rhythm it is the same as the atrial rate.

vagal maneuvers

actions taken to stimulate the vagal nerve and slow the heart rate; may be recommended by a doctor to stop certain dysrhythmias

transient rhythm

a rhythm that comes and goes

sustained rhythm

a rhythm that is always present

retrograde

moving backward; in cardiology, an impulse that travels backward compared to the usual cardiac conduction path

premature junctional complex

a cardiac rhythm in which an early impulse is generated by an irritable area of the AV junction; characterized by an abnormal P wave

junctional escape beats

a cardiac rhythm in which the AV junction area generates an impulse because the SA node is either slow to generate an impulse or does not generate one at all; as in premature junctional complexes, the P wave is abnormal, but these beats are late while PJCs are early.