EKG INTERPRETATION

EKG INTERPRETATION

EKG Basics

  • Vertical grid: 5 mm = 0.5 mV

  • Horizontal grid: 5 mm = 0.2 seconds

    • P-R interval: Interval from the start of P wave to the start of QRS complex

    • S-T segment: Segment between the end of the S wave and the start of the T wave

Five Steps of EKG Interpretation

  1. Heart Rate (HR): What is it?

  2. Rhythm: Regular or irregular?

  3. P Wave: Is there one for every QRS? Upright? Uniform?

  4. P-R Interval: Normal range is 0.12 – 0.20 seconds (3 – 5 small squares)

  5. QRS Complex: Are they alike? What is the length?

Normal Sinus Rhythm (NSR)

  • Rate: 60 – 100 beats per minute (bpm)

  • Rhythm: Regular

  • P Waves: Normal; each P wave is followed by a QRS

  • P-R Interval: Normal, 0.12 – 0.20 seconds

  • QRS Complex: Normal, < 0.12 seconds

  • Treatment: None required

Sinus Bradycardia

Characteristics

  • Rate: < 60 bpm

  • Rhythm: Regular

  • P Waves: Normal; each P wave followed by a QRS

  • P-R Interval: Usually normal, 0.12 – 0.20 seconds

  • QRS Complex: Normal

Causes

  • Common in normal individuals with healthy hearts

  • Medications and parasympathetic stimulation may cause it

Types

  1. Absolute Sinus Bradycardia: HR < 60, normal for the patient, well tolerated

  2. Relative Sinus Bradycardia: Not well tolerated; can compromise cardiac performance leading to:

    • Hypotension

    • Syncope

    • Decreased cardiac output (ßCO)

    • Congestive heart failure (CHF)

    • Shock

Treatment

  • Treat the underlying cause

  • Medications: Atropine, pacemaker

Sinus Tachycardia

Characteristics

  • Rate: 100 - 150 bpm

  • Rhythm: Regular

  • P Waves: Each P wave is followed by a QRS

  • P-R Interval: ≤ 0.12 – 0.20 seconds

  • QRS Complex: ≤ 0.12 seconds in width

Causes & Implications

  • Most common arrhythmia in critically ill patients

  • Increased oxygen consumption and decreased diastolic refill can cause myocardial ischemia

  • Treat underlying causes: fever, pain, hypoxemia, hypovolemia, drugs, hypotension, sepsis, heart failure

Supraventricular Tachycardia (SVT)

Definition

  • General term for all tachycardia dysrhythmias > 100 bpm

Types

  1. Paroxysmal Supraventricular Tachycardia (PSVT): Caused by idiopathic reasons, caffeine, or stress

  2. Paroxysmal Atrial Tachycardia (PAT): Associated with CHF, chronic hypertension, valve disease, aging

Symptoms

  • Chest pain

  • Tiredness

  • Dizziness

  • Lightheadedness

  • Shortness of breath (SOB)

  • Palpitations

Treatment

  • Address underlying cause

Characteristics of PAT or SVT

  • Rate: 150 to 240 bpm

  • Rhythm: Regular

  • P Waves: Abnormal; may be hidden or precede the QRS

  • P-R Interval: Usually not measurable

  • QRS Complex: ≤ 0.12 seconds in width

Premature Atrial Contraction (PAC)

Definition

  • Single impulse originating outside the SA node

  • Occurs sooner than the next beat would be expected

Characteristics

  • Rate: Usually normal

  • Rhythm: Regular except for PAC

  • P Waves: Differ in shape, size, and location from normal P waves

  • P-R Interval: Variable

  • QRS Complex: Normal, < 0.12 seconds

Causes

  • Caffeine

  • Tobacco

  • Sympathomimetic drugs

Treatment

  • Underlying cause and Lidocaine

Atrial Flutter

Definition

  • However, an irritable site causes rapid multiple electrical impulses

  • The AV node plays an important role in regulating impulses (4:1, 3:1 conduction)

Types of Ventricular Response

  1. Slow Ventricular Response: A flutter with a ventricular rate < 60 bpm

  2. Rapid Ventricular Response: A flutter with a ventricular rate 100 – 150 bpm

Characteristics

  • Atrial Rate: ~180 to 400 bpm

  • Ventricular Rate: Varies but always less than atrial

  • Rhythm: Usually regular

  • P Waves: Sawtooth configuration (F-waves) with a possible regular or variable relationship with the QRS

  • PR Interval: Not measurable

  • QRS Complex: <0.12 seconds

Causes

  • Myocardial Infarction (MI)

  • Hypoxia

  • Digitalis toxicity

  • Congestive heart failure (CHF)

Treatment

  • Medications/shock therapy 3: 1 ratio (considered high priority)

Atrial Fibrillation

Definition

  • Most common atrial dysrhythmia in the elderly

  • Characterized by:

    • Absence of P waves

    • Presence of multiple ectopic sites firing simultaneously

    • “F” waves or fibrillatory waves

  • When the rhythm is irregularly irregular, it is typically associated with underlying heart diseases such as CHF

Characteristics

  • Atrial Rate: 300 - 400 bpm

  • Ventricular Rate: Varies but always less than atrial rate

  • Rhythm: Variable irregular (irregularly irregular)

  • P Waves: Fibrillatory waves (f-waves) of varied configuration, no relationship with QRS

  • PR Interval: Not measurable

  • QRS Complex: Normal, < 0.12 seconds

Treatment

  • Medications/shock therapy

  • Anticoagulants or antithrombolytics to mitigate stroke risk

Junctional Rhythms

Definition

  • AV junction assumes the pacing role in absence of SA node activity

Characteristics

  • Rate: Normal intrinsic junctional rate of 40-60 bpm (can accelerate to 60-100 bpm)

  • Rhythm: Regular

  • P Waves: May be inverted or absent

  • PR Interval: Absent, inverted or short

  • QRS Complex: Normal

Causes

  • AV node damage

  • Electrolyte disturbances

  • Digitalis toxicity

  • Heart failure

  • Rheumatic fever

  • Myocarditis

Premature Ventricular Complexes (PVCs)

Definition

  • Premature electrical discharge (contraction) of the ventricle.

  • A single ectopic complex occurs earlier than expected next complex.

Characteristics

  • Rate: Depends on underlying rhythm and number of PVCs

  • Rhythm: Occasionally irregular

  • P Waves: Present and upright in the underlying rhythm; absent with PVCs

  • PR Interval: Not present with PVCs

  • QRS Complex: Wide and bizarre, ≥ 0.12 seconds

Types

  1. Unifocal: PVCs appear alike, originating from one single site

  2. Multifocal: PVCs have different shapes, originating from different sites

  3. Couplet: Two PVCs occurring together without a normal complex in between

  4. Runs of Ventricular Tachycardia (V Tach): Three or more PVCs in succession

Causes

  • Myocardial ischemia

  • Increased emotional stress or physical exertion

  • Congestive heart failure

  • Electrolyte imbalance

  • Digitalis toxicity

  • Acid-base imbalances

  • Blunt force trauma-induced cardiac contusions

Treatment

  • Lidocaine and address underlying causes

Ventricular Tachycardia (V-Tach)

Definition

  • Defined as three or more PVCs at a rate greater than 100 bpm

  • The rhythm commonly overrides the normal pacemaker of the heart.

Characteristics

  • Rate: 100 – 250 bpm

  • Rhythm: Atrial rhythm may not be present; ventricular regular

  • P Waves: May be present or absent; if present not associated with QRS

  • PR Interval: None

  • QRS Complex: Wide and bizarre, > 0.12 seconds

Causes

  • Myocardial ischemia

  • Hypoxia

  • Electrolyte imbalance

  • Cardiomegaly

  • Myocarditis

  • Valvular heart disease

  • Increased anxiety or physical exertion

  • Underlying heart disease

Treatment

  • With Pulse: Lidocaine and cardioversion

  • Without Pulse: CPR and defibrillation

Torsades de Pointes

Definition

  • Means "Twisting of Points"

  • Similar rhythm to V-Tach

  • Variation in QRS complexes width and shape

Characteristics

  • Rate: 100 – 250 bpm

  • Rhythm: Atrial rhythm may not be present, ventricular regular

  • P Waves: May be present or absent; not associated with QRS

  • PR Interval: None

  • QRS Complex: Wide and bizarre, > 0.12 seconds

Causes

  • Hypocalcemia

  • Hypokalemia

  • Hypomagnesemia

  • Overdose of tricyclic antidepressants or anti-dysrhythmic drugs

  • Acidosis

  • Heart failure

  • Female gender

  • Often seen in alcoholics

Treatment

  • Magnesium for stabilization

Ventricular Fibrillation (V-Fib)

Definition

  • Fatal dysrhythmia if untreated, often seen as the initial rhythm in sudden cardiac arrest.

  • Characterized by multiple weak ectopic foci firing in the ventricles, leading to uncoordinated contractions.

Characteristics

  • Rate: Cannot be discerned

  • Rhythm: Rapid and unorganized

  • P Waves: Absent

  • PR Interval: None

  • QRS Complex: None

Causes

  • Acute myocardial infarction

  • Myocardial ischemia

  • Drug overdose

  • Hypoxia

  • Coronary artery disease (CAD)

  • Cardiomyopathy

Treatment

  • CPR, Oxygen, rapid defibrillation, and medications

Asystole

Definition

  • Complete termination of electrical activity in the heart, represented by a flat line on the EKG strip.

  • Important to verify rhythm in multiple leads to rule out fine V-Fib.

Characteristics

  • Rate: Absent

  • Rhythm: Absent

  • P Waves: Absent

  • PR Interval: None

  • QRS Complex: None

Treatment

  • CPR and oxygen

  • Defibrillation is not indicated for asystole.

Causes

  • Unsuccessful resuscitation attempts

  • Massive myocardial infarction

  • Hypothermia

  • Acidosis

  • Hypovolemia

  • Cardiac tamponade

  • Cardiac trauma

  • Tension pneumothorax

  • Ventricular aneurysm

  • Complete heart block

Pulseless Electrical Activity (PEA)

Definition

  • Condition where there is dissociation between electrical and mechanical activity of the heart.

  • ECG monitors show a visible rhythm, but the patient has no palpable pulse.

  • Clinically, the patient is dead.

Causes

  • Hypovolemia

  • Hypothermia

  • Hypoxia

  • Electrolyte imbalances (hypo/hyperkalemia)

  • Cardiac tamponade

  • Tension pneumothorax

  • Thrombosis (pulmonary or coronary)

  • Toxins

Treatment

  • CPR to restore blood circulation.

Heart Blocks

  • Heart blocks are electrical impulses generated at the SA node that may get blocked at points in the conduction system.

  • Classified into:

    • First Degree AV Block

    • Second Degree AV Block Mobitz Type I (Wenckebach)

    • Second Degree AV Block Mobitz Type II

    • Third Degree AV Block

First-Degree AV Block

Characteristics

  • Rate: Based on the underlying rhythm

  • Rhythm: Regular

  • P-Waves: Yes, upright and uniform

  • PR Interval: > 0.20 seconds (5 small boxes)

  • QRS Complex: Yes, < 0.12 seconds

Treatment

  • None required if the patient is stable.

Second-Degree Type I (Wenckebach)

Characteristics

  • Atrial Rate: Unaffected

  • Ventricular Rate: Slower than atrial

  • Rhythm: Atrial regular; ventricular irregular

  • P Waves: Yes, for conducted beats

  • PR Interval: Progressively prolongs until a QRS is dropped

  • QRS Complex: Yes, < 0.12 seconds

Treatment

  • Monitor and assess the patient.

Second-Degree Type II

Characteristics

  • More serious than Type I

  • Intermittent interruptions in electrical conduction.

  • P Waves occur in a regular pattern; some without a QRS complex.

  • Identified by the ratio of P waves to QRS complexes (2:1, 3:1, 4:1).

Causes

  • Septal wall necrosis

  • Acute MI

  • Acute myocarditis

  • Coronary artery disease (CAD)

Treatment

  • Atropine and possible pacemaker implementation.

Third-Degree AV Block

Characteristics

  • Complete heart block, the most severe form.

  • Complete blockage of conduction between the atria and ventricles.

  • Atria and ventricles pace independently.

  • No relationship between P waves and QRS complexes.

Causes

  • Coronary ischemia

  • Acute myocarditis

  • Myocardial infarction

  • Drug toxicity

Treatment

  • Medications and pacing; permanent pacemaker may be necessary.

Pacemakers

Definition

  • Electric pacemakers replace the SA node’s function in pacing the heart.

Types

  1. External Pacemakers

  2. Internal Pacemakers

  3. Transvenous Pacemakers

Indications

  • Second and third-degree heart blocks and symptomatic bradycardia.

Functioning

  • Electrodes attached to a battery-operated pace generator; can be:

    • Fixed: Fires impulses at a specific rate continuously

    • Demand: Fires only if the patient's heart rate drops below a preset rate.

Rhythms for Cardioversion

  • Atrial Fibrillation (Rapid, symptomatic)

  • Atrial Flutter

  • Supraventricular Tachyarrhythmias (SVT)

  • Unstable Ventricular Tachycardia (V-Tach) with a Pulse

Shocking Protocols

Cardioversion

  • Synchronized Cardioversion:

    • Monophasic: 200 J

    • Biphasic: 120 – 200 J

    • Indicated for unstable A-Fib and A-Flutter. 50 - 100 J.

Defibrillation

  • Defibrillator Settings:

    • Biphasic: Initial 120 J and subsequent 200 J

    • Monophasic: 360 J for all shocks

EKG Review

  • Rhythm recognition

  • Causes of arrhythmia

  • Treatment for arrhythmia

Treatment Plans

H’s & T’s (ACLS)

  • H’s:

    • Hypovolemia

    • Hypoxia

    • Hydrogen ions (acidosis)

    • Hypo/Hyperkalemia

    • Hypothermia

  • T’s:

    • Tension Pneumothorax

    • Cardiac Tamponade

    • Toxins

    • Thrombosis (pulmonary)

    • Thrombosis (coronary)

Sinus Bradycardia (ACLS)

Assessment

  • Is it causing hypotension or altered LOC, signs of shock, angina, or acute heart failure?

  • If No: Monitor & observe.

  • If Yes: Administer Atropine and treat underlying cause.

Additional Considerations

  • Possible transvenous pacing

  • Medications: Dopamine or Epinephrine when applicable.

Sinus Tachycardia (ACLS)

Assessment

  • Treat underlying cause; administer Oxygen if hypoxemia is present.

  • Monitor the patient. Is it causing hypotension, altered LOC, signs of shock, angina, or acute heart failure?

    • If Yes: Synchronized cardioversion, sedation, or Adenosine.

    • If No: Determine QRS width.

If Wide QRS:

  • IV access, 12 lead EKG, and consider Adenosine, Procainamide, or Amiodarone.

If Narrow QRS:

  • IV access, 12 lead EKG, Vagal maneuvers, or Beta Blockers.

Atrial Flutter (ACLS)

Summary

  • Not life-threatening but can lead to A-fib if untreated.

  • Medications: Digoxin, Beta Blockers, or Calcium Channel Blockers.

  • Once heart rate is slowed, consider synchronized cardioversion to normalize rhythm.

Atrial Fibrillation (ACLS)

Summary

  • A serious arrhythmia due to decreased cardiac output.

  • Medications: Digoxin, Beta Blockers, or Calcium Channel Blockers.

  • Consider synchronized cardioversion once heart rate is slowed.

  • Use anticoagulants/antithrombolytics to reduce blood clot risks.

Heart Blocks (ACLS)

Treatment Recommendations

  • First Degree: Treatment is not required as long as the patient is stable.

  • Second Degree Type I Mobitz I (Wenckebach): No treatment is needed while the patient is stable.

  • Second Degree Type II Mobitz II: Requires Atropine and pacemaker due to low cardiac output risk.

  • Third Degree: Requires Atropine, and temporary to permanent pacemaker placement.

Premature Ventricular Contraction (PVC) (ACLS)

Treatment

  • Treatment based on frequency and underlying cause.

  • When PVCs are frequent, paired, or multifocal, treat the underlying cause.

  • Medications: Beta & Calcium Channel Blockers.

  • Know that the rhythm can rapidly progress to ventricular tachycardia.

Ventricular Fibrillation (ACLS)

Recommendations

  • Ensure quality BLS (CPR) is performed.

  • Attach monitor/AED to identify a shockable rhythm.

  • If shockable: Biphasic defibrillator settings of 120—200 J, Monophasic at 360 J.

  • Administer Epinephrine & Amiodarone; follow with H’s & T’s assessment. Repeat actions as necessary.

Pulseless Ventricular Tachycardia (ACLS)

Protocol

  • Ensure quality BLS (CPR).

  • Attach monitor/AED to identify a shockable rhythm.

  • Shockable: Biphasic 120—200 J; Monophasic 360 J.

  • Administer Epinephrine & Amiodarone; follow with H’s & T’s assessment. Repeat actions and remember to check pulse.

Pulseless Electrical Activity (PEA) (ACLS)

Protocol

  • Quality BLS (CPR) is essential.

  • Attach monitor/AED to determine rhythm and if it's shockable.

  • Shockable: Same as previous protocols.

  • Administer Epinephrine & Amiodarone; follow with H’s & T’s assessment, and repeat as needed.

Asystole (ACLS)

Protocol

  • Quality BLS (CPR) is critical.

  • Attach monitor/AED, but shockable rhythm identification is vital.

  • Treatments include administering Epinephrine & Amiodarone with consistent follow-ups for rhythm checks and assessments for H’s & T’s issues.

ST Segment Elevation

Key Finding

  • The most significant finding in myocardial infarction (MI) is the presence of elevated ST segments on EKG.

J Point

  • The point where the end of the Q wave and the ST segment meet is referred to as the J point.

  • If the J point is greater than 2 mm above the baseline, it aligns with an ST segment elevation myocardial infarction (STEMI).

Evolution of STEMI

Stages of Elevation

  1. Initial elevation phase

  2. Progression and development of Q waves seen in persistent ST elevation.

  3. Subsequent normalization over time.

ST Segments - Additional Findings

Types of ST Changes

  • Elevated, concave ST segments: Indicative of conditions like pericarditis.

  • Depressed or "scooped" ST segments: Seen in digitalis toxicity.

  • Tombstone or fireman's hat ST: Indicative of myocardial infarction (MI).

T-Waves

Hyperkalemia Indicators

  • Characteristics of T waves in hyperkalemia include:

    • Tall, peaked T waves

    • Wide flat P waves

    • Widening QRS complexes

    • Disappearing ST segment

    • Merging of QRS and T waves

Hypokalemia Indicators

  • Appearance of U waves with:

    • Depressed ST segments

    • Flattened T waves

    • Widening QRS complexes

Conclusion

  • Understanding EKG interpretation is crucial for diagnosing and treating various cardiac conditions, emphasizing timely recognition and management of arrhythmias and other heart-related issues.