ECG Flashcards
Where is the base of the heart located?
Level of the second rib
Where is the apex of the heart located?
Towards the left hip, rest on the diaphragm between the 5th-6th rib
What is the right and left atrias separated by?
Interatrial septum
What blood does the right atrium receive?
It receives deoxygenated blood returning from the systemic circulation
What blood does the left atrium receive?
Receives oxygenated blood returning from the pulmonary circulation
What separates the left and right ventricles?
Interventricular septum
Where does the right ventricle pump blood to?
The lungs
Where does the left ventricle pump blood to?
The rest of the body
What does the superior vena cava do?
Transports blood from parts of the body superior to the diaphragm to the right atrium
What does the inferior vena cava do?
Transports blood from parts of the body below the diaphragm to the right atrium
What does the coronary sinus do?
Transports deoxygenated blood back to the right atrium from coronary circulation
What does the pulmonary artery do?
Transports deoxygenated blood to the lungs
What does the pulmonary vein do?
Returns blood from the lungs to the left atrium
What does the aorta do?
Pumps blood out of the heart, largest artery of the heart
Where is the Atrioventricular (AV) valve located?
Located between the atria and the ventricles
What are the two AV valves?
- Tricuspid
- Mitral (bicuspid)
What does the semi lunar valve do?
Prevents backflow of blood into the ventricles
What are the two semi lunar vlaves?
- Pulmonary valve
- Aortic valve
What is the pericardium?
Surrounds the heart and roots of the great vessels
What are the two layers of the pericardium?
- Parietal layer
- Visceral layer
What is the epicardium?
A serous membrane that forms the innermost layer of the pericardium and the outer surface of the heart
What is the myocardium?
Is the muscular middle layer of the wall of the heart
What is the endocardium?
The thin, smooth membrane which lines the inside of the chambers of the heart and forms the surface of the valves
What is pericarditis?
Inflammation of the pericardium
What is endocarditis?
An inflammation of the inner lining of the heart
What is myocarditis?
An inflammation of heart muscle
what is cardiac tamponade?
Is compression of the heart produced by the accumulation of fluid or blood in the pericardial sac
What is the pulmonary circuit?
- Blood enters the right atrium through (inferior vena cava, superior vena cava, coronary sinus)
- Pass down to the right ventricle
- Than enters the pulmonary arteries
- Go into the left and right lung
- Carbon dioxide is unloaded, and oxygen picked up
- Returns to the left atrium through pulmonary veins
What is the systemic circuit?
- Left atrium to left ventricle to the aorta
- enters the aorta (the right and left coronary)
- Goes to the arteries reaching body tissues, branch into small capillaries
- Oxygen leaves blood to enter body tissue, carbon dioxide from tissue cells is picked up
- Capillaries join to form veins leading back to the heart
What includes the left main coronary artery?
- Left anterior descending (LAD)
- Left circumflex artery
What includes the right coronary artery?
Includes the posterior descending artery
What do both the right and left coronary artery do?
Returns blood back to the right atrium through the coronary sinus
What is the dominant pacemaker of the heart
SA node
What is Polarization?
Depolarization?
Repolarization?
- Polarization=Resting state during which no electrical activity occurs
- Depolarization=When the cardiac cell is stimulated “contraction of the muscle”
- Repolarization=The returning to a resting state
What are the major ions that affect cardiac function?
- Sodium
- Potassium
- Calcium
What is refractory periods?
When the cell cannot be re-stimulated (it is necessary to allow the ventricles sufficient time to empty)
What is automaticity?
Ability to spontaneous initiate an impulse
What is excitability?
Ability to respond to an impulse
What is conductivity?
Ability to receive and transmit an impulse
What is contractility?
Ability to contract in response to an impulse
What is the sinus node?
- The hearts natural pacemaker
- Initiates heart rates between 60-100 bpm at rest
What is the atrioventricular Node (AV node)?
- Receives impulses from SA node
- Delivers impulses to the His-Purknje network
- Delivers heart rates between 40-60bpm (if SA node fails to deliver impulses)
What is the bundle of His?
Begins conduction to the ventricles
What is the Purkinje network?
Moves the impulse through the ventricles for contraction
What is called the escape rhythm?
The Purkinje network that initiate heart rates between 20-40 bpm
What is the automatic nervous system?
Controls of the heart rate and force of contractility
Which leads are the bipolar leads?
I, II, III
Which leads are the augmented unipolar leads?
aVR, aVL, aVF
Which leads are the precordial or chest leads?
V1, V2, V3, V4, V5 and V6
What are the cardiac deflections?
P,Q,R,S,T
What is the purpose of an ECG?
- The amount of voltage generated by the heart
- The time required for the voltage to travel through the heart
What will an ECG not reflect?
- Mechanical function of the heart
- Etiology and pathology of the heart disease
- Structural and functional impairment
- Coronary heart disease when related to silent ischemia
For the triangle in bipolar leads, where is lead I
Left arm and right arm
For the triangle in bipolar leads, where is lead II?
Right arm and left leg
For the triangle in bipolar leads, where is lead III?
Left arm and left leg
What does the a in aVL stand for?
augmented lead
What is the normal paper speed?
25 mm/second
What are three clinically acceptable ECG?
Baseline: must be constant, horizontal or flat and free from artifacts, wherever possible
Leads: must be correctly place connect patient cable
Tracing: properly centered, coded and labelled correct leads, patients name, date and time
What are two technical errors?
- Reversed arm leads
- Chest leads hooked up incorrectly
What is a wandering baseline?
Weaves up and down rhythmically with a “snakelike” motion
this artifacts makes it difficult to evalulate ST segment
How do you fix a wandering baseline artifact?
- Dry electrodes
- Loose connections
- Patient cable swinging or dangling
What is the most common artifact and has no fixed pattern?
Muscle artifact
What does an alternating current (AC) artifact look like?
recognized by its uniform and regular saw-tooth appearance. (60 cycle interference)
What is the cause of alternating current artifacts?
Leakage of 60 cycle electrical current from: nearby electrical equipment which may not be property grounded, such as a ventilator, electric beds, etc
Where are the normal placements for on the arms and legs?
Mid-calf and mid-forearm
Which leads should not be compromised where at all possible?
Precordial leads
What are 6 types of patients that may need modifications?
- Isolation
- Burns
- Geriatric
- Mastectomy and breast implants
- Pediatric
- Psyhiatric
What does the mean QRS axis represent?
The average of instantaneous forces generated during a sequence of ventricular depolarization
What does the normal QRS axis range from?
0 degrees to +90 degrees
What is the left axis deviation range?
0 degrees to -90 degrees
What is the range for right axis deviation?
between +90 up to +180 degrees
What is the range for extreme or indeterminate axis?
-90 degrees to +180 degrees
What are 4 causes of abnormal axis?
- When right and left ventricle depolarization do not occur together
- When the muscle mass of one ventricle is hypertrophied (enlarged)
- When there is a conduction delay or block in one part of the ventricle
- The heart has physically shifted or is rotated abnormally in the chest cavity
What is the order of heart rates?
300-150-100-75-60-50-43-38-30
What does the P wave represent?
atrial depolarization or contraction
What does the PR interval represent?
The onset of atrial depolarization to onset of ventricular depolarization
(the time required or the impulse to travel from the SA node, through the atria to the AV node)
Where is the PR interval measured and what is the normal measurement?
- Measured from the start of the P wave to the start of the QRS
- The normal measurement is between 0.12-0.20 seconds
Where is the PR segment measured?
Measures the end of atrial depolarization to start of ventricular depolarization
What is the PR segment?
Time required for the delay in conduction from the SA node to the AV node
Where is the PR segment measured?
end of P wave to start of QRS
Is there any electrical activity in the PR segment?
No
What does QRS represent?
represents ventricular depolarization
What is the QRS complex?
the time required for the electrical impulse to travel from the AV node through the Purknjie system
What is the normal duration for the ORS complex?
0.8-0.12 seconds
What is the ST segment?
the time from the end of ventricular depolarization to start of ventricular repolarization
what is the T wave?
repolarization of the ventricles
What is the QT interval?
start of ventricular depolarization to end of ventricle repolarization
what is the interval for QT interval?
0.28-0.44 seconds
What is a normal conduction ratio?
1:1
What is the conduction ratio?
refers to the number of atrial contractions (P-P) that occur in relation to contraction of ventricles (R-R)
What is the normal beats per minute?
60-100 per minute P-P and R-R also regular
What do the leads look like in a normal sinus rhythm?
Constant P configuration in any given lead
-Upright in leads I,II and aVF and inverted (negative) in aVR
What is the time for the PR interval?
between 0.12-0.20 seconds
What is the normal QRS interval time?
less than 0.12 seconds, with similar morphology
What is the normal QT interval?
Between 0.28-0.44 seconds
What does a normal sinus rhythm mean?
Means the electrical impulse starts in your sinus node
What is the bpm for sinus tachycardia?
greater than 100 bpm (only difference from normal sinus rhythm)
What is the causes, symptoms and treatment for sinus tachycardia?
Causes: demand by the body for increased cardiac output
Symptoms: shortness of breathe, fatique
Treatment: hemorrhage, infection
What is the bpm for sinus bradycardia?
Less than 60bpm
What is the causes, symptoms and treatment for sinus bradycardia?
Causes: Medications, excess vagal tone, MI
Symptoms: may be lightheaded dizzy or lack energy
Treatment: if symptomatic a pacemaker or medication
What is sinus arrhythmia?
The rhythm is irregular in both the atria and ventricles
What are the causes, symptoms and treatment for sinus arrhythmia?
Causes: usually related to respiration
Symptoms: Usually no symptoms
Treatment: none
What is sick sinus syndrome?
Brady/Tachy syndrome= Combined = irregular heart rates bradycardia and tachycardia
What are the causes, symptoms and treatment of brady/tachy syndrome?
Causes: something wrong with the SA node or atrial arrhythmia
Symptoms: palpitations, light-headedness, dizziness, fatigue
Treatment: medications if heart rate rapid and if pauses or marked bradycardia a pacemaker may be required
What are the rhythms originating in the AV junction?
Escape: 40-60 bpm
Accelerated: 60-100 bpm
What is a junctional rhythm?
No P wave or inverted P wave
What are rhythms originating in the atria?
- Premature atrial Contraction (PAC)
- Atrial tachycardia
- Atrial fibrillation (most common)
- Atrial flutter (most common)
When does atrial rhythms occur?
when an impulse from anywhere in the atrium overrides the SA node by ectopic beats
What is Premature Atrial Contraction (PAC)?
- P wave is early
- Makes rhythm appear to be irregular
- QRS is normal size
What is Supraventricular Tachycardia (SVT)?
- General name for arrhythmias that start above the ventricles.
- Usually begin and end suddenly
- Can last anywhere from seconds to hours
What rhythms are types of SVT?
- Atrial Tachycardia
- Atrial fib
- Atrial Flutter
What is Atrial Tachycardia?
- Sudden short bursts of atrial beat
- More the 3 PACs on a row
What is atrial fibrillation?
Multiple ectopic foci in the atria firing causing the atria to depolarize in a chaotic manner (quivering instead of normal contraction)
What is the atrial rate for atrial fib?
200-600bpm
What is the most common type SVT?
A fib
What are fib waves?
Non-measureable P waves
Is ventricular rhythm always irregular in A fib?
Yes
What is atrial flutter?
A single irritable focus in the atria which repeatedly fires creating a re-entry circuit that depolarizes the atria and gains control
Which heart rhythm is the saw-tooth?
Atrial Flutter
What are the two rhythms originating in the ventricles?
Active- includes fast rhythms = comes from the foci with one of the ventricles
Passive-includes slow rhythms =Come from Purkinje network
What are some characteristics for Premature Ventricular Complex (PVC)?
- Wide bizarre complex usually > 0.12 seconds
- Large T waves generally in the opposite direction as QRS
- P wave if present is unrelated to QRS
What do bigeminal PVC’s look like?
Every other beat is a PVC
What do coupled PVCs look like?
Occur in pairs
What do trigeminal PVC’s look like?
Every third beat is a PVC
What is a potential life threatening arrhythmia?
Ventricular Tachycardia
What is monomorphic ventricular tachycardia?
Means that the appearance of all the beats match each other in each lead of a surface electrocardiogram (ECG)
What is polymorphic ventricular tachycardia?
Has beat to beat variations in morphology
What is ventricular fibrillation?
Is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles, making them quiver rather than contact properly
What is the heart rate for monomorphic ventricular tachycardia?
140-250 bpm
What is the heart rate for ventricular fibrillation?
300-600
What is the most common cause of sudden cardiac death?
Ventricular fibrillation or polymorphic VT
What has a lethal rhythm?*
Ventricular fibrillation
What is ventricular Asystole?
A standstill heart beat (flat line)
What are the two heart blocks?
- Bundle branch blocks
- AV blocks
What are bundle branch blocks?
Bundle branch blocks are obstruction in the transmission of the electrical impulse through one of the bundle branches wither the right or left
What is the bundle branch block pattern?
- QRS complex is >0.12 seconds
- RR prime either in V! and V2 (right bundle branch block)
- RR prime in V5 and V6 (left bundle branch block) - deep wide S waves V1-V6
What is the right bundle branch block ECG diagnostic criteria?
- QRS duration >120ms
- RSR’ pattern in V1-3 (“M-shaped” QRS complex)
- Wide, slurred S wave in lateral leads (I, aVL, V5-6)
What is the Left bundle branch block ECG diagnostic criteria?
- QRS duration > 120ms
- Dominant S wave in V1
- Broad monophasic R wave in lateral leads (I, aVL, V5-6)
- Absence of Q waves in lateral leads
- Prolonged R wave peak time > 60ms in leads V5-6
What are the causes of bundle branch blocks?
Coronary artery disease, cardiac tumors, cardiomyopathy, pericarditis, myocarditus, CHF
What are the different types of AV blocks?
- First degree AV block
- Second Degree AV block (type 1, type 2)
- Third degree AV block
When do AV blocks occur?
When there is block in conduction of impulses between in atria and ventricles
What is a 1st degree AV block?
A sinus impulse is conducted normally to the AV node, but delayed in the AV node longer than usual
What is a 2nd degree AV block?
A sinus impulse is conducted normally to the AV node but each impulse has more and more difficulty passing through the AV node. There are two types of 2nd degree AV blocks
What is second-degree AV block Mobitz 1
Progressive prolongation of the PR interval until there is failure to conduct and a ventricular beat is dropped
What is Mobitz type 2
Every 2nd sinus impulses fails to be conducted to the ventricles
(atrial rate = 75 bpm, ventricular rate = 42 bpm)
What is the third degree AV block?
No impulse conduction from the atria to the ventricles
atrial rate = 130 bpm ventricular rate = 37 bpm
What is acute coronary syndrome?
Umbrella term used to cover any group of heart conditions which are cause by the sudden formation of blood clots or fatty deposits within a coronary artery known as artherosclerosis
What is Ischemic Heart Disease?
Name given to explain the lack of blood flow and oxygen to the heart muscle (major cause is atherosclerosis and most common symptom is angina)
What is CHF?
The inability of the heart to pump blood forward at a sufficient rate to meet the metabolic demands of the body
What is cardiomyopathy?
Heart disorder which affects the myocardium
What are the three different types of cardiomyopathy?
- Dilated
- Hypertrophic
- Restrictive
What will Ischemia look like?
ST segment depression > 1mm and T wave inversion
What will myocardial injury look like?
ST segment elevation >1mm
What will an MI look like?
ST segment elevation >1mm with or without significant Q wave
How long are Q waves normally?
< 0.03 seconds and 1/3 height of the R wave
What leads are a inferior MI?
Leads II, III and aVF
Which leads are anterior MI?
Leads V1, V2, V3, V4
Which leads are lateral MI?
Leads I, aVL, V5 and V6
When should 15 and 18 lead ECG be done?
- All acute or recent inferior wall MI’s with ST elevation in leads II, III and aVF, perform right sided chest leads RV4, RV5 and RV6
- ST segment depression or elevation >1mm in V1 to V4 perform posterior leads V7, V8, V9
- ST segment elevation >1mm in V5 or V6 perform posterior leads V7, V8 and V9
When are right sided chest leads performed?
- Acute inferior and posterior wall MI
- Positive for right ventricular involvement
When are posterior leads used?
Acute posterior wall MI
What will low potassium do?
- Prominent U wave
- Sagging of the ST segment
What will high potassium do?
-Tall peaked, symmetrical “tenting” T waves usually in the precordial leads
What will low calcium do?
- Prolonged the ST segment
- Produces a prolonged QT interval
What will high calcium levels do?
- A shortened QT interval
- Wide and round T wave
What will high magnesium do?
Flattening of the T wave
What will hypothermia do in ECGs?
- Bradycardia
- Low T waves
- Intervals prolonged
- PVC possible
What is a pacemaker?
is an electronic device used to treat patients who have symptoms caused by abnormally slow heartbeats
Who gets a pacemaker?
- sympotomatic conduction disturbances (2nd and 3rd degree AV blocks)
- Sick sinus syndrome
- Syncope
What are the three functions of the pacemaker?
- Sensing
- Pacing
- Capture
What is appropriate sensing in pacemakers?
Sensing the ability of the pacemaker to see intrinsic beats and respond by resetting the timing interval
What is a implantable cardiac defibrillator (ICD)?
-An implantable cardiac defibrillator (ICD) is a small electronic device installed inside the chest to prevent sudden death from cardiac arrest due to life threatening abnormally fast heart rhythms
What can a ICD do?
- Continuously monitor patient rhythm
- Diagnoses rhythm changes
- Treats life threatening arrhythmias
- All have back up pacemaker
