Week 6- ECG Flashcards
PART 1: INTRODUCTION
PART 1: INTRODUCTION
- Routine cardiac events are triggered by _______ events.
- Electrical events can be detected and visualized via _____.
- Altered ECG patterns reflect a pathology in what?
- electrical events
- ECG
- conduction system or a process that alters these electrical events
What are the (3) unique properties of cardiac myocytes?
- Automaticity
- Rhythmicity
- Conductivity
CARdiac
Automaticity:
- What is automaticity?
- They __________ discharge.
- Think ________ heart.
- They are able to discharge/depolarize without stimulation from a nerve.
- automatically discharge
- transplanted heart
Rhythmicity:
- What is rhythmicity?
- Describe the hierarchy of rhythmicity and their discharge rates. (3)
- What creates the sinus rhythm?
- Depolarization occurs at regular intervals, therefore cardiac muscle cells can depolarize at regular intervals.
- SA Node (60-100/min), AV Node (40-60/min), His-Purkinje Fibers (30-40/min)
- SA Node
- What is important to know about the hierarchy of rhythmicity?
- What does this mean?
- The faster/higher discharge rate predominates. (Autonomic influence > SA > AV > Purkinje)
- This means that if the normally predominating (SA Node) one is malfunctioning, the next highest will take over.
Conductivity:
- What is conductivity?
- _____like squeeze. What is the purpose of this?
- Heart muscle cells have ability to spread impulses to adjoining cells very quickly without nerve involvement.
- Wavelike squeeze (to promote movement of blood through atria into ventricles, and out of heart)
Describe the AP in a 0-4 step process.
- ) Na+ influx making inside of cell more +.
- ) K+ leaves cell causing slight repolarization until plateau.
- ) Ca+ (in) and K+ (out) leads to sustained plateau.
- ) Eventually Ca+ (in) stops and K+ (out) remains, leading to repolarization.
- ) AP remains until next depolarization.
PART 2: WIGGERS DIAGRAM (ECG) & PQRST COMPLEX
PART 2: WIGGERS DIAGRAM (ECG) & PQRST COMPLEX
- When the wave of depolarization is moving a positive electrode located under the skin, the ECG records a simultaneous _______ deflection.
- A wave of repolarization moves over a positive electrode results in a _________ deflection.
- upward
- downward
ECG tracings are _________ recordings of electrical events/ionic events occurring within the myocytes.
superficial recordings
P Wave:
- ______ ________ is depicted on the ECG tracing as the P wave.
- Initiated via the ________.
- The impulse is spread to the L side via the _________ bundle.
- atrial depolarization
- SA Node
- Bachmann bundle
PR Interval:
- Determines time it takes impulse to travel from ________ to _________.
- How is this useful?
- SA Node to AV Node
- Helps to determine how healthy the heart is in terms of how fast it is able to spread electricity.
QRS Complex:
- ________ ________ is depicted on the ECG tracing as the QRS complex.
- What is the pathway of the His-Purkinje fibers and why does this matter?
- Higher QRS = ______ muscle
- ventricular depolarization
- His-Purkinje fibers travel in wall of ventricle and help to promote wavelike contraction. This directs blood flow into the pulmonary/aortic valves.
- Higher QRS = bigger muscle
T Wave:
- ________ _________ is depicted on the ECG tracing as the T wave.
- The interval from the beginning of the QRS Complex to the apex of the T wave corresponds to the ______ _______ period. What is this?
- In most leads, the T wave is _________ and reflects to repolarization of the myocytes.
- ventricular repolarization
- absolute refractory period, this is where it can no longer depolarize
- positive (upward deflection)
PART 3: ECG RECORDING/LEADS
PART 3: ECG RECORDING/LEADS
What is the isoelectric point?
- When looking at an ECG, the x-axis line that the ECG is hovering around.
- Above = + voltage change, Below = - voltage change
- The standard 12-lead ECG consists of ___ limb leads and ___ chest leads.
- Think of each lead as what?
- 6 limb leads and 6 chest leads
- Lead is a different view of the heart from a different angle.
- Standard limb leads = ?
- Augmented limb leads = ?
- I, II, and III
- aVR, AVL, and aVF
Chest Leads (views):
- Thee six chest leads of the ECG are ___, ____, ____, ____, ___, and _____.
- Show gradual changes in all the recordings.
- Record in a ________ plane.
- V1-V6
- horizontal plane
- Leads V1/V2 are placed over the ______.
- Leads V3/V4 located over ____________.
- Leads V5/V6 look at ________.
- V1/V2 = R side of heart
- V3/V4 = interventricular septum
- V5/V6 = L side of heart
Describe all 6 chest leads placement.
- V1 = 4th IC space to R of sternum
- V2 = 4th IC space to L of sternum
- V3 = Directly between leads V2 and V4
- V4 = 5th IC space at midclavicular
- V5 = level with V4 at left anterior axillary line
- V6 = level with V5 at left midaxillary line
-V4r = 5th IC space at R midclavicular
Describe telemetry lead placement.
- Right arm, left arm, right leg, left leg
- Can be done at shoulders/hips or wrists/ankles, but most often done proximal.
What is a way to remember telemetry lead placement?
- ) White right
- ) Snow over grass
- ) Brown ground
- ) Smoke over fire
Why does the amplitude of the QRS complex increase as we move from V1 to V6?
The larger the muscle mass, the higher the amplitude of the complex. (LV stronger than RA/RV)
Limb Leads:
- Lead I = ___ to ___
- Lead II = ______ to _______
- Lead III = ______ to _______
- Lead aVR = ____ to _____
- Lead aVL = ____ to _____
- Lead aVF = ____ to ____
- I = R to L
- II = top R to bottom L
- III = top L to bottom L
- aVR = whole L to top R
- aVL = whole R to top L
- aVF = top to bottom
The direction of the heart based on anatomical orientation is bests correlated with which lead?
Lead II (main lead of reference)
What (3) things are we looking for with a single lead assessment?
- Heart Rhythm/Rate
- Normal Waveforms
- Abnormal Waveforms
ECG Recording:
- Vertical deflections = voltage (__ mV/mm, small square)
- Horizontal = time (___s, small box)
- 5 big squares = __s, 30 big squares = __s
- Vertical = 1mV/mm
- Horizontal = 0.04s
- -5 big squares = 1s, 30 big squares = 6s
Determine HR From ECG Strip:
- Describe the 300, 150, 100 method.
- Describe an alternative method.
- ) Locate R wave on heavy black line.
- ) Count off “300, 150, 100, 75, 60, 50” for each heavy black line that follows until the next R wave falls.
- ) Bold line it falls on represents the HR.
- ) Count the number of large boxes between two adjacent R waves.
- ) 300/ this count
- ) Yields estimated HR
Single limb monitoring can only accurately assess _____ and _______.
rate and rhythm
Assessment of the Cardiac Cycle. (8)
- ) Evaluate the P wave. (Is it normal and upright, and is there a P wave before every QRS? Do all the P waves look alike?)
- ) Evaluate the P-R interval. (Normal duration is 0.12 to 0.20 seconds)
- ) Evaluate the QRS complex. (Do all QRS complexes look alike?)
- ) Evaluate the QRS interval. (Normal duration is 0.06 to 0.10 seconds)
- ) Evaluate the T wave. (Is it upright and normal in appearance?)
- ) Evaluate the R-R wave interval. (Is it regular?)
- ) Evaluate the heart rate (6-second strip if regular rhythm; normal rate is 60 to 100 beats per minute).
- ) Observe the patient and evaluate any symptoms. (Do the observation, symptoms, or both correlate with the arrhythmia?)
PART 4: AV BLOCKS
PART 4: AV BLOCKS
How many degrees of AV Block are there?
- 1st Degree AV Block
- 2nd Degree AV Block
- 3rd Degree AV Block
1st Degree AV Block:
- When do 1st Degree AV Blocks occur?
- What does this result in on an ECG?
- How would we classify a 1st Degree AV Block?
- Occurs when the impulse is initiated in the SA Node, but DELAYED on the way to the AV Node.
- Results in a prolonged PR interval. (AV conduction time prolonged)
- PR interval >.2s, normal QRS complex (.06-.1s)
2nd Degree AV Block (Wenckeback/Mobitz 1):
- What are 2nd Degree Wenckeback AV Blocks? Where do they occur?
- What does this result in on an ECG?
- Does the lengthening of PR interval followed by a dropped QRS occur in a repetitive cycle?
- Transient disturbance that occurs high in AV junction and prevents conduction of SOME impulses through the AV node.
- Initial P wave precedes each QRS complex, but eventually a P wave may stand alone. Progressive lengthening in PR interval, with eventual drop of QRS complex.
- Yes
2nd Degree AV Block (Mobitz II):
- What are 2nd Degree Mobitz II AV Blocks?
- What does this result in on an ECG?
- Intermittent non-conducted P waves without progressive prolongation of PR interval.
- P waves “march through” at a constant rate.
3rd Degree AV Block:
- What are 3rd Degree AV Blocks?
- ______ and ________ fire at their own inherent rate.
- What does this result in on an ECG?
- ______ can be wide (>.1s)
- No impulses that are initiated above the ventricles are conducted to the ventricles.
- atria and ventricles
- QRS complex
- What is a way to remember 1st Degree AV Block?
- What is a way to remember 2nd Degree (Wenckeback) AV Block?
- What is a way to remember 2nd Degree (Mobitz II) AV Block?
- What is a way to remember 3rd Degree AV Block?
- 1st Degree = “If R is far from P, then you have first degree”
- 2nd Degree (Wenckeback) = “Longer, longer, drop, then you have Wenckeback”
- 2nd Degree (Mobitz II) = “If some p’s don’t get through, then you have Mobitz II”
- 3rd Degree = “If P’s and Q’s don’t agree, then you have 3rd degree”
Which AV Block is the most dangerous and why?
3rd Degree because we are not having correlated electrical activity, the heart itself will start to malfunction.
How are each of the blocks treated?
1st degree
-benign and usually not treated
2nd degree
- Dependent on the type of 20 block
- No treatment necessary or
- Pacemaker placement
- Result of an MI
3rd degree (LIFE THREATENING)
- MI, degeneration of the conducting system
- Permanent pacemaker placement
- Medical emergency
PART 5: ARRHYTHMIAS
PART 5: ARRHYTHMIAS
What are some different Atrial Arrhythmias? (2)
- Paroxysmal Atrial Tachycardia (PAT)
- Atrial Fibrillation
PAT:
- What is Paroxysmal Atrial Tachycardia?
- How do we know it is atrial tachycardia?
- A sudden recurrence of atrial tachycardia.
- There is a P-wave, if it wasn’t atria we wouldn’t have a P-wave.
Atrial Arrhythmias:
- P-wave may be merged with previous ______.
- P-R interval may be difficult to determine but are
- T-wave
- <0.2s
- identical
- 0.06s-0.1s
- regular
What are some things that can cause PAT?
-Emotional factors; overexertion; hyperventilation; potassium depletion; caffeine; nicotine and aspirin sensitivity; rheumatic heart disease; mitral valve dysfunction, PE
What are some symptoms that can occur if PAT rapid rate continues for a period of time? (3)
- Dizziness
- Weakness
- SOB
Atrial Fibrillation:
- What is A.fib?
- _______ are absent, thus leaving a flat or wavy baseline.
- How is the R-R interval defined?
- QRS complex is between ___-___s.
- Erratic quivering/twitching of atrial muscle caused by ectopic foci in atria that emit electrical impulses constantly.
- P-waves
- irregularly irregular
- 0.06s-0.1s
How do you calculate HR with A.fib since it is irregular?
Look at QRS complexes in a 6s ECG strip and multiply it by 10.
Atrial Fibrillation:
- What are some things that can cause A.fib?
- Not considered life-threatening unless what?
- lack of atrial “kick” = decrease CI by ___-___%
- Potential for developing mural thrombi
- Advanced age, CHF, ischemia or infarction, cardioyopathy, digoxin toxicity, drug use, stress or pain, rheumatic heart disease, renal failure
- Unless HR is elevated
- 15-30%
What are some different Ventricular Arrhythmias? (3)
- Premature Ventricular Complexes (PVCs)
- Ventricular Tachycardia (Vtach)
- Ventricular Fibrillation
Premature Ventricular Complexes (PVCs):
- What is PVC?
- The QRS complex is classically described as what?
- When the heart _____ __ _____.
- Each specific site in ventricles has different looking ECG complex.
- PVC generally followed by compensatory ______.
- Occurs when an ectopic focus originates an impulse from somewhere in one of the ventricles.
- Wide and bizarre looking QRS without a P-wave and followed by a complete compensatory pause.
- Skips a beat
- pause
Treatment of PVCs depends on what (3) things?
- Underlying cause
- Frequency and severity of PVCs
- Symptoms associated
When are PVCs considered life threatening? (5)
- ) Are paired together.
- ) Are multifocal in origin.
- ) Are more frequent than 6 per minute.
- ) Land directly on the T-wave.
- ) Are present in triplets or more.
When are PVCs usually considered benign?
-When isolated, without symptoms, and fewer than 6/min.
Vtach:
- What is Vtach?
- What does this result in on an ECG?
- Ventricular rate of ventricular tachycardia is between ____-___ bpm.
- It can be the precursor to what?
- Series of 3 or more PVCs in a row, occurs because of rapid firing by a single ventricular focus with increased automaticity.
- P-waves are absent, 3 or more PVCs in a row, prolonged Q-T interval, and “Torsade de Pointes”
- 100-250 bpm
- Vfib
What are some causes of Vtach? (4)
- ischemia or acute infarction
- CAD
- hypertensive heart disease
- medication reaction
What are some treatment options for Vtach? (3)
- Cardioversion
- Defibrillation
- Medication (lidocane, bretylium tosyliate, or procainiamide)
- With Vtach, CO is severely diminished and often converts to _______.
- Is it a medical emergency?
- Individuals who remain conscious with this arrhythmia may be lightheaded or near __________.
- Vfib
- Yes
- syncope
Ventricular Fibrillaton (Vfib):
- What is Vfib?
- How does this present on an ECG?
- Defined as erratic quivering of ventricular muscle resulting in no CO. (multiple ectopic foci fire, creating asynchrony)
- ECG shows grossly irregular up/down fluctuations of the baseline in an irregular zigzag pattern.
- Is Vfib a medical emergency?
- What are the causes?
- Treatment is _________ as quickly as possible followed by cardiopulmonary resuscitation, supplemental O2, and med injections.
- Yes
- Same as Vtach
- defibrillation
Ventricular Arrhythmia Tiered Therapy. (3)
- ) Antitachycardia Pacing (Vtach)
- ) Cardioversion Shock (Vtach
- ) Defibrillation (Vfib)
PART 6: OTHER FINDINGS FROM A 12-LEAD ECG
PART 6: OTHER FINDINGS FROM A 12-LEAD ECG
Hypertrophy:
- Determined by looking at voltage in ___ and ____.
- RV hypertrophy is defined as a large ___-wave in V1, which gets progressively smaller in V2, V3, and V4.
- LV hypertrophy defined as a large ___-wave in V1 and a large R-wave in ___ that have combined voltage of >35mV.
- V1 and V5
- RV Hypertrophy = large V1
- LV Hypertrophy = large S-wave in V1 and large R-wave in V5.
Ischemia:
-How does this present on an ECG?
- Inverted T-wave
- S-T segment depression
Ischemia, Infarction, or Injury:
- ST segment depression at rest in presence of chest pain = ____________, may indcate a pending transmural infarction.
- ST segment depression in absence of ischemia or angina may be due to _________ toxicity.
- ST segment elevation or depression is diagnostic for ___________; presence of Q-wave is also diagnostic of infarction.
- Leads that demonstrate presence of T-wave inversion, ST segment changes, or Q-waves identify _______ of ischemia, injury, or infarction.
- subendocardial infarction
- digitalis
- acute infarction
- location
- STEMI = _________
- NSTEMI = ________
- STEMI = full occlusion (MI)
- NSTEMI = artery narrowing
