Define Electrocardiography
Process of recording the variations of electrical potential produced by the heart
Who invented the first sensitive and reliable instrument for measuring and recording cardiac potential
William Einthoven
Who published the first well known textbook of electrocardiography
Thomas Lewis
In what decade was the first portable ECG available
1950
Define electrocardiograph
Instrument used to record the variations in electrical potential produced by the heart
Define Analog
something that is similar in appearance to something else
How does analog differ from digital
Analog measures in mm and hundredths of a second. Digital measures more precisely in mv and msecs
Name the 3 basic functions of the ECG
Input, signal averaging and output
Electrical signal collected by the ECG is amplified by _________ before it is transmitted to the galvanometer
20 000 000 000
What is the most controllable function of the ECG
Output
List 3 of the main differences between a single and multichannel ECG
Technology All precordial leads must be connected at the same time When tracing is complete it doesn`t have to be mounted Cost and time effective
What are some main components of ECG
power supply amplifier galvanometer recording mechanism pt lead cables sensitivity control lead selection paper speed electrodes
What is the importance of general machine care
ensure prolonged life of the equipment
2 reasons for when it would be necessary to change the standardization of an ECG
If voltage is too high or low when recording specialty leads evaluating arrhythmias
Define voltage
amount of pressure in an electrical loop which is measured in volts
2 main sources of electrical hazard to pt
malfunctioning equipment leakage current
What can increase when the ECG is subjected to corrosive and humid environments
Leakage Current
Define AC
flow of electrons in one direction which is constant
Define macro and microshock
macro - occurs when relatively large amounts of electrical current flows across a persons body micro - hazard produced when a small amount of electrical current passes internally near pt`s heart
What is the function of the flat prong or neutral pin
provides a direct path back to the power source
What are some preventative measures the tech can use to identify and prevent electrical hazards
replace frayed cord or broken insulation check for broken 3 prong plugs inspect pt`s environment for 2 wire ungrounded devices report receptacles which do not hold the 3 prong snuggly Never use extension cords
What is the name given to pictures of the heart taken from different directions
Leads
Define Bi-polar leads
A recording of electrical differences between two points of reference
What is Einthoven`s Law
Sum of the amplitude of the recorded complexes in Lead I and Lead III is = to amplitude recorded in Lead II
What does AV stand for in relationship to the unipolar limb leads
Augmented Voltage
Where is Zero potential located
Center of the heart
Recording the third dimension of the heart is the function of the ____ ____
Chest Leads
A small bump felt where the manubrium meets the sternal body is known as the
Sternal Angle
Why is it important to place the fingers in the ICS and follow them one in front of the other
prevent skipping an ICS
What are the qualities of a technically and clinically acceptable ECG
Standardization - 1mv 10mm high Clarity - each deflection is visible Baseline - must be constant Leads - should be approx 3-6 complexes Tracing - properly centered, coded and labelled
What are some causes of single artifact
Loose electrode connection lead switch over operator induces static electricity metallic particles in skin or in electrode cream surgical implanted metal plate or screw
Causes of wandering baseline
muscle tension pt not comfortable pt physical or mental condition tech incomplete pt prep and attitude
2 causes of somatic tremor
lack of relaxation poor electrode contact loose electrode connection ¸breathing pt conversation pt cable swinging or dangling
How would you correct baseline that is too thick
clean wax or build up
The ___ is the recording of the electrical activity of the heart
ECG
____ ___ is an invasive procedure using a unipolar lead to identify atrial activity or P waves
Esophageal lead
This is an emergency procedure used to terminate VFIB or VT
Defibrillation
This is the initial emergency management of the victim who has lost consciousness, is pulseless and has no respirations
CPR
This is used to diagnose and correct SVT caused by re entry
Vagal maneuvers or carotid massage
This is a condition in which the heart is located in the right side of the chest cavity
Dextrocardia
This is intended to prevent parenteral, mucous membrane and non-intact skin exposure to health care workers to blood borne pathogens
Universal precautions
Some conditions where it may be impossible to acquire the exact anatomical positions of the precordial leads
Chest or thoracic surgery chest trauma presence of skin growth monitoring equipment
What is the purpose of protective or reverse technique
to protect the pt from infectious bacteria which may cause infection
What are 3 diagnostic limitations to the ECG
mechanical function of the heart etiology and pathogenesis of heart dx structural and functional impairment coronary artery dx related to transient or silent ischemia
When should a rhythm strip be obtained for evaluation of arrhythmias
HR below 40BPM Multifocal or frequent ectopy Any pt who is not in sinus rhythm
When should double standard be used
voltage is too low
Conditions associated with tamponade
trauma to chest infection neoplastic dx myocardial rupture post cardiac surgery post CPR perforation of chamber wall with cath or pacing wire
What is the purpose of the right leg sensor
serves as ground to keep the average voltage of the pt the same as that of the recording instrument
Why is a 15 lead ECG done
posterior MI RV MI
What is the significance of the fibrous barrier
only one path for an impulse to reach the ventricles (AV junction) Protects ventricles from too many impulses
Which structures of the conduction system are supplied by the LAD
lower junctional tissue BOH RBB Anteriosuperior fascicle of LBB Part of purkinje network
Structures of conduction system innervated by the PNS
SAN, AVN and Atria
Normal range of impulse formation for the SAN, AV Junction and Purkinje`s
SAN - 60-100BPM AV Junction - 40-60 BPM Purkinje - 20-40 BPM
2 Physiological benefits of the AVN
Protect ventricles by limiting the number of impulses that it will allow to be conducted (no more than 180 per min) Delays all impulses for about 0.10 secs to allow for atrial contraction before ventricular contraction
What structures are supplied by the RCA
SAN in 60% of pop AVN in 90% of pop upper junctional region, midnodal area
Once the impulse has travelled through the conduction system what happens next
The muscle tissue that was ready to receive it becomes activated and depolarizes
What are 3 methods by which ions may move across a cell membrane
Diffusion Osmosis Active transport pumps
Electrical potential gradient that exists across the cell membrane when the cell is at rest is called:
RMP
Which of the following statements about the property of automaticity is NOT true
It occurs because the myocardial cell membrane allows Na+ ions to slowly leak back into the cell after the RMP is reached It is necessary because the heart has no nerve supply
What part of the action potential curve represents cell activation or depolarization
Phase 0
When a cell membrane reaches threshold potential the following statements are TRUE
Cell is depolarized in an all or none fashion Cell membrane has a more positive membrane potential voltage than RMP
Which cells possess spontaneous diastolic depolarization
any cell with the property of automaticity: SAN, AV Junction and Purkinjes
Which cardiac cell typically has the LEAST negative RMP
SAN
Which cardiac cell typically has the most perpendicular phase 0 slope
Ventricular myocardium
Which cardiac cell typically has the steepest rise of phase 4
SAN
Which cardiac cell typically has the longest refractory period
Purkinje
Atrial Depolarization is
Posteriorly, Downwards and to the left
Depolarization of the ventricular septum is
from left to right, anteriorly and superiorly
Depolarization of the free walls of the right and left ventricles
to the left, posteriorly and inferiorly
Late depolarization of the ventricles
to the left, posteriorly and superiorly
What specifically is the hexaxial reference system useful for
to illustrate whether the QRS axis is normal, deviated to the right or left
Patient has aortic valve disease which has caused LVH, which part of the conduction system would be most vulnerable to injury
Left Anterior Fascicle
Normal septal depolarization is from
left to right
Septal depolarization in LBBB is from
right to left
Depolarization in LBBB is from
late activation of LV
Depolarization of RBBB is from
late activation of RV
What is typical QRS duration of RBBB, LBBB, LAH and LPH
RBBB - 0.12-0.13 LBBB - 0.12-0.16 LAH - 0.06-0.10 LPH - 0.06-0.10
The SAN is normally the dominant pacemaker because its cells have which distinct features
Fastest rate of automaticity and highest slope of diastolic depolarization (phase 4)
The SAN is normally the dominant pacemaker because its cells have which distinct features
Fastest rate of automaticity and highest slope of diastolic depolarization (phase 4)
What conditions may cause enhanced automaticity
Hypokalemia Hypocalcemia Digitalis toxicity stretching of conductive fibers fever hypoxia hypercapnia catecholamine release trauma, MI and sympathetic stimulants
What conditions may cause enhanced automaticity
Hypokalemia Hypocalcemia Digitalis toxicity stretching of conductive fibers fever hypoxia hypercapnia catecholamine release trauma, MI and sympathetic stimulants
T of F - SVT may be due to enhanced automaticity, reentry or a combination of both
TRUE
Myocardial Ischemia is a common contributing factor to the development of reentry because:
conductivity is slowed
T of F - VT may be due to enhanced automaticity, reentry or a combination of both
TRUE
Atrial Flutter is believed to most commonly be due to:
Interatrial reentry
A complete block of the conduction system may be:
Permanent, temporary, Intermittent, drug induced
Name 2 passive escape rhythms
Junctional (idiojunctional) and idioventricular
Name 2 areas of the conduction system where a block can occur:
SAN, AVN and bundle branches
Name an arrhythmia that can develop as a result of a triggered activity
coupled extrasystoles, PSVT and VT
Has a phasic variation of rate due to changes in vagal tone typically affected by respiratory cycle
Sinus Arrhythmia
Arrhythmia originating in SAN which has a rate less than 60BPM
Sinus Bradycardia
Arrhythmia originating in SAN which has a rate greater than 100BPM
Sinus Tachycardia
Paroxysmal tachycardia originates in SAN
SAN reentry tachycardia
An isolated early beat in the cycle initiated by an atrial focus
PAC
Characterized by AFIB with slow ventricular response and or brady-tachy syndrome as well as other supraventricular arrhythmias
SSS
Most likely cause of paroxysmal tachycardia originates in AVN
PSVT
F waves formed regularly at 250-400 BPM with regular or irregular AV block
Atrial Flutter
Passive rhythm takes over by default with a typical rate of 40-60 BPM
AV Junctional rhythm or idiojunctional rhythm
Varying P wave morphology and PRI with rates 100-250 BPM and associated with chronic lung dx
MAT
Mechanism in sinus arrest is depression of impulse ____ and mechanism of sinus block is depression of impulse ______
formation, conduction
If the pause in the rhythm is a multiple of the P-P Interval, then the diagnosis is
Sinus Block
In 2nd degree Mobitz I, AV block, the PRI is gradually ____ until the next P wave has no QRS complex following it because it has been ____
prolonged, blocked
In 2nd degree mobitz II AV block the PRI is ___ and may be either a normal duration or _____. Conduction is not 1:1 because the impulse is periodically ______ at the AV junction from reaching ventricles
constant, prolonged, blocked
In 3rd degree AV block, there is a complete ____ of impulses from the atria to the ventricles resulting in the existence of ___ pacemakers in the heart; one stimulating the ____ and the other stimulating the ____
blockage, 2, atria, ventricles
The passive rhythm that develops in complete AV block may originate from an _______ focus or _____ focus
Idiojunctional, Idioventricular
When slow HR associated with conduction blocks causes signs and symptoms, the most common mode of treatment is ______
Pacemaker
Ventricular pre-excitation occurs because an _____ pathway exists, which allows the sinus impulse to enter the ventricles by a shorter faster route than if it were travelling through the _____ pathways
accessory, normal
WPW syndrome can occur if the anomalous accessory pathway called the ____ __ ____ exists
Bundle of Kent
The delta wave in WPW syndrome is an initial ____ of the QRS comples. Ventricles may be activated totally from by the impulse from AP. This is called _____ pre-excitation. When the ventricles are activated totally by the impulse from normal _____ system pathway it is called ___ pre-excitation
slurring, maximal, conduction, zero
Whether or not the classic short PRI, delta wave, abnormal Q waves and prolonged QRS interval are present, any pt with PSVT should be suspected to have an anomalous AP T of F
TRUE
ECG characteristics of AFIB in presence of WPW
Irregular rhythm 160-300 BPM, usually 250-300 BPM
Why is the rate in WPW able to exceed 220 BPM
Because it does not travel through normal conduction pathway, no AVN to block and protect ventricles from high rates
The rapid rate caused by WPW can cause the risk of development of ...
VFIB
Will vagal maneuvers be effective in WPW
NO
Will WPW respond to cardioversion
YES
What drug therapies may be used in WPW
Quinidine, Procainamide, Disopyramide, aprinidine, amiodarone,encainide, propafenone and sotalol
The most frequently seen AV re entry tachycardia of WPW is Orthodromic tachycardia which is characterized by a ______ QRS
Normal
Will AV reentry tachy caused by WPW be regular or irregular, what is the typical rate, will there be a delta wave, respond to vagal maneuvers, respond to cardioversion, QRS may be wide because
regular, 130-220, No, maybe, maybe, because of aberrancy
AV reentry tachycardia caused by WPW may be treated with
Digitalis, propranolol, diltiazem, amiodarone, verapamil and encainide
Usual rate of idioventricular rhythm is
20-40 BPM
What is a full compensatory pause
rhythm of SAN is not interrupted when a PVC occurs and is very useful to diagnose if the ectopic beat is ventricular in origin
The danger of PVC`s in the presence of ischemia heart disease or cardiomyopathies is that they may be the forerunner to
Sudden death, onset of VT and Onset of VFIB
The danger of R on T is the potential of the development of
VT or VFIB
TDP is a type of __ which is associated with an underlying rhythm with ____ QTI. The condition is most commonly medication induced. What 3 drugs are associate with the development of TDP
VT, Prolonged Quinidine, Disopyramide and tricyclic antidepressants
The 2 most common rhythm disturbances that can cause the onset of VFIB are
PVC and VT
T of F - when the ventricles are fibrillating the heart muscle is able to eject only a very small volume of blood, not adequate to maintain BP
False - there is no circulation of even a small amount of blood
Aberrant ventricular conduction may be either RBB or LBB aberrancy, although most of the time it is _____ aberrancy
RBB
AFIB and PAC`s frequently are conducted with aberrancy because aberrant ventricular conduction occurs because of _____ of cycle length
shortening
T of F - QRS duration of a normal newborn is less than an adults
TRUE
T or F - T waves in V1 are upright throughout childhood as well as adulthood
False
T of F - amplitude of the R wave in V1 is usually greater than the S wave in V1 in an infant of less than one month
True
T or F - At birth the RV is thicker and dominant than the LV
True
T or F - Newborns with Pulmonary Atresia are almost completely dependant in a patent ductus for pulmonary blood flow
True
T of F - by the time a child is 3-8 yrs, the precordial leads will assume the adult QRS pattern
True
T of F - HR of 130 BPM for a newborn is considered tachycardia
False
T or F - episodes of sinus tachy and brady lasting longer that 15 secs is abnormal
True
The normal HR for a 2-3 month old is
95-180 BPM
It can be said that most of the children who develop SVT have ____
no associated cardiac disease
The most common form of congenital heart disease is
VSD
The most common cyanotic congenital heart defect beyond infancy is
Tetralogy of Fallot
The most common cyanotic congenital heart defect in infancy is
Transposition of great vessels
What are 3 cardiac defects that obstruct LV or RV outflow
Aortic stenosis, Pulmonic Stenosis and Coarctation of Aorta
Which of the following is not a Class I antiarrhythmic Quinidine, Diltiazem, Procainamide, Mexiletine or Propanolol
Diltiazem
Which classification of antiarrhythmics has as the primary effect the slowing of AV conduction
Class IV
Which is a common serious side effect of amiodarone pulmonary toxicity, CHF, RF, Impotence or Peripheral Edema
Pulmonary Toxicity
Which of the following is NOT a frequent or severe side effect of Beta adrenergic blocking agents:
Thyroid Dysfunction
Which of the following would be the most effective treatment of pt with nocturnal angina
add a beta blocker in addition to nitrate therapy
Identify the modified chest lead that is most useful in detection of ST segment change due to ischemia
Modified lead V5
What conditions can alter ST segment causing false positive ST segment changes
Body position (sitting) hyperventilation digoxin, quinidine electrolyte imbalance post prandial LVH Conduction system abnormalities pre excitation smoking
What modified chest lead is most useful in detection of P waves
modified V1, also V2 and lead II and III
Resting HR is normally highest in the morning and the lowest between 3-5 am, what is this normal phenomenon referred to as
Diurnal variation or circadian rhythm
The J point of the ST segment is the point at which
The QRS ends and the ST segment begins
T or F - most centres use bipolar modified chest recording leads for ambulatory ECG recording
True
T or F - with a conventional tape processing recorder, the entire cardiac rhythm is recorded in analog format and all analysis is done off line
True
T or F - Pt should be advised to perform minimal activity and no exercise enduring testing to minimize the development of artifact
False
T or F - Ambulatory ECG is a very useful diagnostic test for pt whose symptoms are suspect of cerebral insufficiency
False
T or F - A pt with a PVC count of over 150 per hour requires DR notification
True
T or F - Silver chloride electrodes should always be used for ambulatory ECG
True
T or F - Nine volt battery can be reused for more than one recording as long as it is removed from the unit between recordings
False
T or F - Disposable electrodes are applied on top of bone or cartilage to minimize artifact
True
T or F - The test strip for a pt with a cardiac pacemaker will not usually have any visible pacemaker spikes or artifact
False
T or F - Abrupt alterations on ST segment that develop fully within 2-3 beats and terminate just as rapidly are due to position artifact and not ischemia
True
Why is superimposition a useful scanning feature
QRS complexes can be studied at 30-480 times real speed VT and premature ectopics quickly processed detects intermittent AFIB and pre excitation
The scanning process that allows every single ECG complex to be printed but on a low amplitude and compressed time so that the ECG complexes are compressed is
Full disclosure
The scanning process that was first used for ectopic beat identification and is now also used for ST segment change identification and pacemaker stimulus recognition is
QRS feature extraction or template comparison correlation technique
The maximum O2 consumption per min per kg of body weight is limited by
Cardiac Output
What is METS
Metabolic Equivalent and measure of O2 consumption