Tachycardia
Causes: Physical activity, anxiety, pain, hyperthyroidism, fever, hypoxemia, anemia, medications, compensation for hypotension.
Symptoms: Shortness of breath, weakness, hypotension, chest pain and/or palpitations. Patients may also be asymptomatic.
Pharmaceutical Interventions:
- Class I Antiarrhythmics: Procainamide, lidocaine.
- Class II Antiarrhythmics: Propranolol, metoprolol, atenolol.
- Class III Antiarrhythmics: Amiodarone, sotalol.
- Class IV Antiarrhythmics: Verapamil, diltiazem.
- Other Antiarrhythmics: Adenosine, digoxin, magnesium sulfate.
Electrical Interventions:
- Cardioversion: Atrial fibrillation, atrial flutter, supraventricular tachycardia, ventricular tachycardia with pulse.
- Defibrillation: Ventricular fibrillation, pulseless ventricular tachycardia.
Card 2
Bradycardia
Causes
Symptoms
Interventions
Answer
Bradycardia
Causes: Heart block, sick sinus syndrome, hypothyroidism, medications, electrolyte imbalances, cardiovascular disease or infection, valsalva maneuvers (e.g., bearing down), excess vagal stimulation (e.g., gagging, vomiting).
Athletes may also have bradycardia, which is a normal/expected finding.
Symptoms: Dizziness, syncope, hypotension, shortness of breath.
Patients may also be asymptomatic.
Interventions:
- Pharmaceutical: Atropine, epinephrine, dopamine.
- Electrical: Pacemaker.
Card 3
Artificial Pacemakers
Atrial Pacing
Ventricular Pacing
AV Pacing
Pacemaker Modes
Answer
Artificial Pacemakers
Pacemakers emit a pacing stimuli, which shows up as a "spike" on an EKG strip.
Atrial Pacing: Used with SA node failure. A spike precedes the P wave.
Ventricular Pacing: Used with a complete AV block. A spike precedes the QRS complex.
AV Pacing: Used with SA node failure and complete AV block. A spike precedes the P wave AND the QRS complex.
Pacemaker Modes:
- Asynchronous: Fires at a constant rate regardless of the heart's electrical activity.
- Synchronous: Fires only when the heart's intrinsic rate falls below a certain rate.
EKG Changes with Key Disorders
Electrolyte Imbalances:
- Hyperkalemia: Peaked T wave, wide/flat P wave, wide QRS complex.
- Hypokalemia: Flattened or inverted T wave, ST depression, presence of U wave (immediately following the T wave), increased amplitude and width of P waves.
- Hypercalcemia: Shortened ST and QT interval.
- Hypocalcemia: Prolonged ST and QT interval.
- Hypermagnesemia: Bradycardia, heart blocks.
- Hypomagnesemia: Tachycardia, prolonged QT interval, flattened or inverted T wave.
Cardiac Disorders:
- Angina: ST depression, T wave inversion.
- Ischemia/MI: ST elevation/depression, T wave inversion, abnormal Q wave.
- Pericarditis: ST elevation.
Respiratory Disorders:
- Pulmonary Embolism: ST elevation, inverted T wave, RBBB.
- COPD: Peaked P waves, low voltage QRS.
Card 5
Escape Beats
What is an Escape Beat?
Key Characteristics of a:
- Ventricular Escape Beat
- Junctional Escape Beat
Treatment
Answer
Escape Beats
An escape beat is an abnormal impulse that follows a sinus pause and occurs late. Identify underlying rhythm first, then identify abnormality.
Ventricular Escape Beat: Initiated in the ventricle. After the pause, the P wave will be absent and the QRS complex will be wide.
Junctional Escape Beat: Initiated in the junctional foci (located at the AV junction). It causes the P wave following the pause to be absent/inverted or the PR interval to be short (
Treatment: Treatment of an escape beat in asymptomatic patients is typically not required.
Card 6
Sinus Pause
What is a Sinus Pause?
Key Characteristics
Treatment
Answer
Sinus Pause
A sinus pause occurs when the SA node fails to initiate an impulse, or if the impulse becomes blocked such that the atria do not depolarize.
During this pause, the P wave, QRS complex, and T wave will be absent.
An "escape beat" may be present after the sinus pause.
Treatment: Treatment of a sinus pause in asymptomatic patients is typically not required.
Card 7
Bundle Branch Block (BBB)
What is a BBB?
Key Characteristics
Treatment
Answer
Bundle Branch Block
A bundle branch block (BBB) occurs when the electrical impulse is delayed through the Bundle of His or bundle branches, resulting in a wide QRS complex (> 0.12 seconds, or greater than 3 small boxes).
A right bundle branch block (RBBB) or left bundle branch block (LBBB) may be present. Identify underlying rhythm first, then identify abnormality.
Treatment: Many patients with a BBB are asymptomatic and don't require treatment. Symptomatic patients or patients with cardiac disease may require a pacemaker or cardiac resynchronization treatment (CRT).
Card 8
3rd Degree AV Block
What is a 3rd Degree AV Block?
Describe the Following:
- Heart Rate (Atrial and Ventricular)
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
3rd Degree AV Block
A 3rd degree AV block causes a complete failure of all impulse conduction from the atria to the ventricles.
Heart Rate: Atrial rate is typically normal (60 - 100 bpm). Ventricular rate is slow (
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Normal, consistent appearance. However, there are more P waves than QRS waves. P waves are NOT associated with QRS complexes.
If Ps and Qs don't agree, then you have a third degree.
PR Interval: Varies.
QRS Complex: Normal or wide duration.
Treatment: Pacemaker.
Card 9
2nd Degree AV Block: Type 2
(Mobitz II)
What is a 2nd Degree Type 2 AV Block?
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
2nd Degree AV Block: Type 2
A 2nd degree type 2 AV block causes a sudden failure of impulse conduction from the atria to the ventricles (without a progressive increase in conduction time).
Heart Rate: Varies. Ventricular rate is less than the atrial rate because some QRS complexes are dropped.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Irregular.
P Wave: Normal, consistent appearance, equal distance apart. More P waves than QRS complexes.
PR Interval: Normal or prolonged, but consistent (unlike 2nd degree block Type 1).
QRS Complex: Some dropped. Normal or wide duration.
If some Ps don't get through, then you have Mobitz II.
Treatment: This type of AV Block is usually permanent and is treated with a pacemaker.
Card 10
2nd Degree AV Block: Type 1
(Mobitz I or Wenckebach)
What is a 2nd Degree Type 1 AV Block?
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
2nd Degree AV Block: Type 1
A 2nd degree type 1 AV block causes a progressive increase in impulse conduction times between the atria and ventricles until one impulse fails to conduct.
Heart Rate: Varies. Ventricular rate is less than the atrial rate because some QRS complexes are dropped.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Irregular.
P Wave: Normal, consistent appearance, equal distance apart. More P waves than QRS complexes.
PR Interval: Variable. Progressively gets longer until QRS complex is dropped.
Longer, longer, longer, DROP! Then you have Wenckebach.
QRS Complex: Some dropped. Normal duration when present (
Treatment: Usually temporary and does not require treatment. If cardiac output is insufficient, atropine can be used.
Card 11
1st Degree AV Block
What is a 1st Degree AV Block?
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
1st Degree Block
A 1st degree AV block causes prolonged impulse conduction times from the atria to the ventricles due to a delay in the AV node.
Heart Rate: Varies, usually 60 - 100 bpm.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P wave: Present, consistent in appearance, one P wave with each QRS complex.
PR interval: Prolonged (> 0.20 seconds, or greater than 5 small boxes), but consistent.
If the R is far from P, then you have first degree.
QRS Complex: Uniform appearance, duration
Treatment: Typically not required, but the patient's rhythm should be monitored in case it progresses into a more severe block.
Card 12
Asystole
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Asystole
Heart Rate: 0 bpm.
Atrial Heart Rhythm: None.
Ventricular Heart Rhythm: None.
P Wave: No P waves.
PR Interval: N/A.
QRS Complex: Absent.
Treatment: CPR.
Card 13
Idioventricular Rhythm
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Idioventricular Rhythm
Heart Rate: 40 bpm for accelerated ventricular rhythm).
Atrial Heart Rhythm: Absent.
Ventricular Heart Rhythm: Regular.
P Wave: No P waves.
PR Interval: N/A.
QRS Complex: Wide QRS duration (> 0.12 seconds or greater than 3 small boxes).
Treatment: Usually transient and typically does not require treatment.
Card 14
Ventricular Fibrillation
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Ventricular Fibrillation
Heart Rate: Unable to assess.
Atrial Heart Rhythm: N/A.
Ventricular Heart Rhythm: Irregular.
P Wave: No P waves.
PR Interval: N/A.
QRS Complex: Unable to assess ("VFib" waves present).
Treatment: Defibrillation. Defib Vfib!
Card 15
Torsades de Pointes
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Torsades de Pointes
Heart Rate: > 100 bpm.
Atrial Heart Rhythm: N/A.
Ventricular Heart Rhythm: Irregular.
P Wave: No P waves.
PR Interval: N/A.
QRS Complex: Wide QRS duration (> 0.12 seconds or greater than 3 small boxes), inconsistent appearance (appears to "twist" around the EKG baseline).
Treatment: IV magnesium, antiarrhythmics, and/or pacing.
Card 16
Ventricular Tachycardia (VT)
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Ventricular Tachycardia (VT)
Heart Rate: > 100 bpm.
Atrial Heart Rhythm: N/A.
Ventricular Heart Rhythm: Usually regular.
P Wave: No P waves.
PR Interval: N/A.
QRS Complex: Wide QRS duration (> 0.12 seconds, or greater than 3 small boxes), consistent appearance of QRS complexes.
Treatment: VT with a pulse is treated with cardioversion or anthiarrhythmics. VT without a pulse requires defibrillation.
Card 17
Premature Ventricular Complexes (PVCs)
What are PVCs?
Describe the Following:
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Premature Ventricular Complexes (PVCs)
PVCs are abnormal impulses that originate from the ventricle and occur early. The premature complex will not have a P wave, and the QRS will be wide. Identify underlying rhythm first, then identify abnormality.
Atrial Heart Rhythm: Irregular (or "regular except" with PVC).
Ventricular Heart Rhythm: Irregular (or "regular except" with PVC).
P Wave: Normal except with PVC (no P wave with PVC).
PR Interval: 0.12 - 0.20 seconds (3 - 5 small boxes) when P wave is present.
QRS Complex: Normal duration ( 0.12 seconds, or greater than 3 small boxes).
Treatment: PVCs are often asymptomatic and do not require treatment. Antiarrhythmics can be used for symptomatic PVCs.
Card 18
Junctional Tachycardia
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Junctional Tachycardia
Heart Rate: > 100 bpm.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Absent, inverted (before or after QRS complexes), or normal (with short PR interval).
PR Interval: If P wave is present and before the QRS complex, the PR interval is short (
QRS Complex: Uniform appearance, duration
Treatment: Typically not necessary. If the heart rate is too fast, antiarrhythmics can be used. Avoid digoxin in patients with junctional dysrhythmias.
Card 19
Accelerated Junctional
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Accelerated Junctional
Heart Rate: 60 - 100 bpm.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Absent, inverted (before or after QRS complexes), or normal (with short PR interval).
PR Interval: If P wave is present and before the QRS complex, the PR interval is short (
QRS Complex: Uniform appearance, duration
Treatment: Typically not necessary. Avoid digoxin in patients with junctional dysrhythmias.
Card 20
Junctional Bradycardia
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Junctional Bradycardia
Heart Rate:
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Absent, inverted (before or after QRS complexes), or normal (with short PR interval).
PR Interval: If P wave is present and before the QRS complex, the PR interval is short (
QRS Complex: Uniform appearance, duration
Treatment: Typically not necessary. If the heart rate is too slow to maintain adequate cardiac output, atropine can be used. Avoid digoxin in patients with junctional dysrhythmias.
Card 21
Junctional Rhythm
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Junctional Rhythm
Heart Rate: 40 - 60 bpm.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Absent, inverted (before or after QRS complexes), or normal
(with short PR interval).
PR Interval: If P wave is present and before the QRS complex, the PR interval is short (
QRS Complex: Uniform appearance, duration
Treatment: Typically not necessary. If the heart rate is too slow to maintain adequate cardiac output, atropine can be used. Avoid digoxin in patients with junctional dysrhythmias.
Card 22
Supraventricular Tachycardia (SVT)
What is SVT?
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Supraventricular Tachycardia (SVT)
SVT describes any abnormally fast heart rate that originates above the ventricles, typically in the atria (e.g., atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia). SVT may occur in between stretches of normal sinus rhythm.
Heart Rate: > 100 bpm (usually 150 - 250 bpm).
Atrial Heart Rhythm: Typically unidentifiable.
Ventricular Heart Rhythm: Regular.
P Wave: Typically not visible. May be hidden in preceding T wave. Check T waves for change in shape.
PR Interval: N/A (because P waves not visible).
QRS Complex: Uniform appearance, duration
Treatment: Cardioversion or antiarrhythmics.
Card 23
Atrial Fibrillation (AFIB)
Describe the Following:
- Heart Rate (Atrial and Ventricular)
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Atrial Fibrillation (AFIB)
Atrial Heart Rate: 350 - 600 bpm (not measurable).
Ventricular Heart Rate: Variable.
Atrial Heart Rhythm: Irregular.
Ventricular Heart Rhythm: Irregular.
P Wave: Absent, "fib waves" (i.e., lots of little bumps) between QRS complexes.
PR Interval: N/A.
QRS Complex: Uniform appearance, duration
Treatment: Cardioversion or antiarrhythmics. Anticoagulation is also recommended to prevent thromboembolism.
Card 24
Atrial Flutter
Describe the Following:
- Heart Rate (Atrial and Ventricular)
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Premature Atrial Complexes (PACs)
What are PACs?
Describe the Following:
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Premature Atrial Complexes (PACs)
PACs are abnormal impulses that originate from the atria and occur early. Identify the underlying rhythm first, then identify the abnormality.
Atrial Rhythm: Irregular (or "regular except" with PAC).
Ventricular Rhythm: Irregular (or "regular except" with PAC).
P Wave: P wave with a PAC will appear prematurely and look different than other P waves. P wave may be hidden in preceding T wave (check T wave for change in shape). After the PAC, a delay may follow the QRS complex or the QRS may be dropped completely.
PR Interval: Normal (0.12 - 0.20 seconds) or prolonged (> 0.20 seconds) depending on prematurity of the impulse.
QRS Complex: Normal, wide, or absent depending on the prematurity of the impulse.
Treatment: Usually not necessary. However, frequent PACs may precede more serious dysrhythmias.
Card 26
Sinus Arrhythmia
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Sinus Arrhythmia
Heart Rate: 60 - 100 bpm.
Atrial Heart Rhythm: Irregular (heart rate increases slightly with inspiration and decreases slightly with expiration).
Ventricular Heart Rhythm: Irregular (heart rate increases slightly with inspiration and decreases slightly with expiration).
P Wave: Present, uniform appearance, one P wave per QRS complex.
PR Interval: 0.12 - 0.20 seconds (3 - 5 small boxes).
QRS Complex: Uniform appearance, duration
Treatment: Sinus arrhythmia is a common finding in children and typically disappears with age. It is not a cause for concern.
Card 27
Sinus Tachycardia
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Sinus Tachycardia
Heart Rate: > 100 bpm.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Present, uniform appearance, one P wave per QRS complex.
PR Interval: 0.12 - 0.20 seconds (3 - 5 small boxes).
QRS Complex: Uniform appearance, duration
Treatment: Determine and treat the underlying cause (e.g., fever, hypotension, pain, anxiety, etc.).
Card 28
Sinus Bradycardia
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
- Treatment
Answer
Sinus Bradycardia
Heart Rate:
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Present, uniform appearance, one P wave per QRS complex.
PR Interval: 0.12 - 0.20 seconds (3 - 5 small boxes).
QRS Complex: Uniform appearance, duration
Treatment: Treatment of asymptomatic bradycardia is not necessary. For symptomatic bradycardia, treatment options include atropine or a pacemaker.
Card 29
Normal Sinus Rhythm
Describe the Following:
- Heart Rate
- Heart Rhythm (Atrial and Ventricular)
- P Wave, PR Interval, QRS Complex
Answer
Normal Sinus Rhythm
Heart Rate: 60 - 100 bpm.
Atrial Heart Rhythm: Regular.
Ventricular Heart Rhythm: Regular.
P Wave: Present, uniform appearance, one P wave per QRS complex.
PR Interval: 0.12 - 0.20 seconds (3 - 5 small boxes).
QRS Complex: Uniform appearance, duration
Card 30
Natural Pacemakers of the Heart
What are the Inherent Rates and Key Characteristics of the Following Pacemakers/Rhythms?
- SA Node (Sinus Rhythm)
- Atrial Foci (Atrial Rhythm)
- Junctional Foci (Junctional Rhythm)
- Ventricular Foci (Ventricular Rhythm)
Answer
Natural Pacemakers of the Heart
SA Node (Sinus Node): The heart's normal pacemaker, it generates a sinus rhythm.
- Inherent Rate: 60 - 100 bpm.
- Key Characteristics: P waves are upright and uniform in appearance, one P wave for each QRS complex.
Atrial Foci: If the SA node fails, the atrial foci take over and generate an atrial rhythm.
- Inherent Rate: 60 - 80 bpm.
- Key Characteristics: Abnormal P wave(s) or, instead of P waves, there may be flutter or fibrillation waves.
Junctional Foci: If the atrial foci fail, the junctional foci (at the AV junction) take over and generate a junctional rhythm.
- Inherent Rate: 40 - 60 bpm.
- Key Characteristics: Inverted/absent P waves, P waves that occur after QRS complexes, or very short PR intervals.
Ventricular Foci: If the junctional foci fail, the ventricular foci take over and generate a ventricular rhythm.
- Inherent Rate: 20 - 40 bpm.
- Key Characteristics: No P waves, abnormally wide QRS complexes.
Card 31
EKG Interpretation: Step 5
Analyze the QRS Complex
Answer
QRS Complex Analysis
Is the QRS duration
Measure the QRS duration with calipers: 1 point at the beginning of the QRS complex, and the other point where the ST segment begins.
Do QRS complexes have a consistent appearance across the strip?
Is there a QRS complex for each P wave?
Card 32
EKG Interpretation: Step 4
Analyze the PR Interval
Answer
PR Interval Analysis
Is the PR interval within the expected range of 0.12 - 0.20 seconds (3 - 5 small boxes)?
Measure the PR interval with calipers: 1 point at the beginning of the P wave, and the other point at the end of the PR segment.
Are PR intervals consistent across the EKG strip?
Card 33
EKG Interpretation: Step 3
Analyze the P Wave
Answer
P Wave Analysis
Are P waves present?
Do they occur regularly?
Do P waves have a consistent appearance across the strip?
P waves should appear upright, smooth, rounded, and with an amplitude up to 2.5 mm (2.5 small boxes high).
Is there one P wave for each QRS complex?
Heart Rate: 6-Second Strip Method
Use for irregular rhythms. Count number of QRS complexes in 6 seconds and multiply by 10. Alternatively, you can count the number of cycles that occur within 6 seconds and multiply by 10.
Tick marks at top of EKG represent 1 second (or 3 seconds, depending on the strip).
Example: See the 6-second strip below. Each tick mark represents 1 second. There are 5 QRS complexes within the 6-second strip. 5 x 10 = 50, heart rate is ~ 50 bpm.
1 small box = 0.04 sec | 1 big box = 0.2 sec | 5 big boxes = 1 sec | 6 sec strip = 30 big boxes
Card 35
EKG Interpretation: Step 2
Determine the Heart Rate:
- Option 2: Big Box Method
Answer
Heart Rate: Big Box Method
Use for regular rhythms. Count number of big boxes between R waves and divide into 300 (i.e., 300 ÷ number of big boxes).
Memory Method: A variation of the big box method is the memory method.
Memorize the heart rate based on the number of big boxes between R waves:
1 = 300 bpm, 2 = 150 bpm, 3 = 100 bpm, 4 = 75 bpm, 5 = 60 bpm, 6 = 50 bpm, 7 = 43 bpm, 8 = 38 bpm.
Example: See the 6-second strip below. There are 5 big boxes between QRS complexes. 300/5 = 60 bpm.
1 small box = 0.04 sec | 1 big box = 0.2 sec | 5 big boxes = 1 sec | 6 sec strip = 30 big boxes
Card 36
EKG Interpretation: Step 2
Determine the Heart Rate:
- Option 1: Small Box Method
Answer
Heart Rate: Small Box Method
Use for regular rhythms (especially faster rhythms). More precise than big box method. Count number of small boxes between two R waves and divide into 1,500 (i.e., 1,500 ÷ number of small boxes).
Example: See the 6-second strip below. There are 12 small boxes between QRS complexes. 1,500/12 = 125 bpm.
1 small box = 0.04 sec | 1 big box = 0.2 sec | 5 big boxes = 1 sec | 6 sec strip = 30 big boxes
Card 37
EKG Interpretation: Step 1
Determine the Heart Rhythm
Answer
Determine the Heart Rhythm
Heart rhythm = regular or irregular. Check both atrial and ventricular rhythms.
Atrial Rhythm: Check regularity of atrial rhythm by assessing the P-P intervals (P wave to P wave) for regularity.
Ventricular Rhythm: Check regularity of ventricular rhythm by assessing the R-R intervals (R wave to R wave) for regularity.
Card 38
EKG Strip Basics
Duration Associated with:
- Small Boxes and Big Boxes
Normal Duration and/or Amplitude of:
- P Wave, PR Interval, QRS Complex, ST Segment, QT Interval, T Wave
Answer
EKG Strip Basics
Duration of Small and Big Boxes:
- Small Boxes: Each small box is 0.04 seconds in duration.
- 5 small boxes = 1 big box (5 x 0.04 seconds = 0.2 seconds).
- 25 small boxes = 1 second, 150 small boxes = 6 seconds,
1,500 small boxes = 60 seconds.
- Big Boxes: Each big box is 0.2 seconds in duration.
- 5 big boxes = 1 second, 30 big boxes = 6 seconds, 300 big boxes = 60 seconds.
Normal Duration and/or Amplitude of EKG Components:
- P Wave: Amplitude up to 2.5 mm (2.5 small boxes high) and duration between
0.06 - 0.12 seconds (1.5 - 3 small boxes).
- PR Interval: Duration between 0.12 - 0.20 seconds (3 - 5 small boxes).
- QRS Complex: Duration between 0.04 - 0.10 seconds. QRS complexes with a
duration
- ST Segment: Amplitude is usually isoelectric (0 mm), but may be between
-0.5 and 1 mm.
- QT Interval: 0.36 - 0.44 seconds (9 - 11 small boxes).
- T Wave: Amplitude up to 10 mm (10 small boxes high).
Card 39
EKG Waveform Components
Identify the Following Components on an EKG:
- P Wave, PR Interval, PR Segment, QRS Complex,
- ST Segment, T Wave
Answer
EKG Waveform Components
Card 40
Heart Conduction System
Where can you find the following on an EKG waveform?
- Atrial Depolarization
- Ventricular Depolarization
- Atrial Repolarization
- Ventricular Repolarization
Answer
Heart Conduction System
Card 41
Heart Conduction System
What are the steps in the heart conduction system?
How are these steps recorded on an EKG?
Answer
Heart Conduction System
SA node (i.e., sinus node) initiates an electrical impulse, which stimulates the atria to depolarize and contract.
Atrial depolarization is recorded as a P wave on the EKG.
The impulse travels down to the AV node, where there is a delay to allow the blood in the atria to empty into the ventricles.
This pause is recorded as the PR segment on the EKG (short flat line after the P wave).
The impulse then travels rapidly to the Bundle of His, then to the left and right bundle branches, then to the Purkinje fibers, then to myocardial contractile cells. Depolarization of the myocardial contractile cells triggers ventricular contraction.
Ventricular depolarization is recorded as the QRS complex on the EKG.
Atrial repolarization also occurs during this time.
Repolarization of the ventricular myocardium then occurs. The ST segment represents the initial phase of ventricular repolarization, and the T wave represents the rapid phase of ventricular repolarization.
Ventricular repolarization is recorded as a T wave on the EKG.
Card 42
12-Lead Electrocardiogram (EKG)
Placement of EKG Leads (10 Electrodes)
Answer
Placement of EKG Leads
The term "leads" refers to how many angles are used to examine the heart's activity. There are12 leads, but 10 electrodes.
Limb electrodes (4)
RA - Right arm
LA - Left arm
RL - Right leg
LL - Left Leg
Chest electrodes (6)
V1 - Fourth ICS, right sternal border
V2 - Fourth ICS, left sternal border
V3 - Midway between V2 and V4
V4 - Fifth ICS, left midclavicular line
V5 - Level with V4, left anterior axillary line
V6 - Level with V5, left midaxillary line