EKG Interpretation

Electrocardiogram

Records cardiac electrical activity.

• Same heartbeat, different view.

Depolarization

The electrical impulse that activates the heart to contract.

Repolarization

The heart muscle relaxes.

P-Wave

Atrial depolarization

PR Interval

Related to the rate of cardiac impulse transmitted from the AV node. The time from when the P starts until the QRS starts.

QRS Complex

Ventricular depolarization

ST Segment

Follows ventricular depolarization and occurs prior to the start of ventricular repolarization.

T Wave

Ventricular repolarization is occurring.

QT Interval

The time for ventricular repolarization to complete.

EKG Strips - 5 Large Boxes

Equals 1 Second

EKG Strips - 15 Large Boxes

Equals 3 Seconds

EKG Strips - 30 Large Boxes

Equals 6 Seconds

EKG Strips - 1 mm (Small Boxes)

Equals 0.04 Seconds

EKG Strips - 5 mm (Small Boxes)

Equals 0.2 Seconds

7 QRS Complexes in 6 Sec

7 X 10 = 70 bpm

Step 1 for ECG Analysis

Calculate heart rate.

Step 2 for ECG Analysis

Determine if the heart rhythm is regular.

Step 3 for ECG Analysis

Assess for P waves.

Step 4 for ECG Analysis

Measure the PR interval.

Step 5 for ECG Analysis

Measure the duration of the QRS complex.

P Wave

SA node, atria depolarization

QRS Wave

Ventricle depolarization

T Wave

Ventricular Repolarization

PR Interval

The start of the P wave to the start of the QRS wave.

QT Interval

The start of the QRS wave to the end of the T wave.

ST Interval

End of the QRS wave to the end of the T wave.

Step 1 of the Five-Step Interpretation Method

HR—Count R spikes for 6 seconds and multiple by 10.

Step 2 of the Five-Step Interpretation Method

Rhythm: Regular or Irregular—Are the R’s evenly spaced?

Step 3 of the Five-Step Interpretation Method

P Wave (Atrial Activity)—Is it there, and is it married to the QRS?

Step 4 of the Five-Step Interpretation Method

PR Interval (Measures Atrial Contraction) -3-5 mini boxes or normal PR interval is 0.12 to 0.2 seconds

Step 5 of the Five-Step Interpretation Method

QRS Complex (Measures Ventricle Activity)—Isthere one? Is it wide? 3 mini boxes or normal QRS is 0.08 to 0.12 seconds

Additional Information

• T  wave represents ventricular repolarization (ventricle is ready for another contraction). T waves should be smooth and upright.

• QT interval is the length of time it takes the electrical impulse to go from the beginning of the ventricle until the ventricle completely repolarizes and is ready for another contraction. QT interval should not exceed 0.45 seconds (350 to 450 milliseconds).

Normal Sinus Rhythm

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

Sinus Bradycardia

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

• Faculty Note:

  • Sinus bradycardia occurs when the SA node sends an electrical impulse slower than 60 bpm.

  • The ECG criteria for sinus bradycardia remains the same as what is expected to be identified during NSR.

  • Causes for SB: genetics, MI, sleep apnea, increased intracranial pressure, decrease in metabolic needs (eating disorder), increased exercise tolerance, hypothyroidism, vagus nerve stimulation (frequent coughing, excessive gagging, and straining for a bowel movement) all may lead to bradycardia.

  • Bradycardia is also associated with Lyme disease, typhoid fever, malaria, Rocky Mountain Spotted Fever, medications, normal aging and prolonged hypoxia.

Medications that cause sinus bradycardia

• Parasympathomimetic (acetylcholine)

• Beta blockers (metoprolol)

• Digitalis glycosides (digoxin)

• Calcium channel blockers (diltiazem)

• Antiarrhythmics (amiodarone)

• Chemotherapy agents (thalidomide)

• Lithium

Sinus Bradycardia: Impact on Overall Health

• Clients may be asymptomatic or symptomatic

• Symptomatic: fatigue, increased shortness of breath, dizziness

  • Safety concern: Falls

• Lab Testing

  • Electrolytes

  • Thyroid hormone panel

  • Troponin

  • Blood and Urine for toxicology

Sinus Bradycardia: Role of the Nurse

• Fall precautions for symptomatic bradycardia

• Identify the cause of bradycardia

• Instruct client on lifestyle changes that will decrease potential for injury.

• Recognize Cues (Assessment)

  • Assess for manifestations of decreased cardiac output

    • Dizziness

    • Chest pain

    • Near syncope

    • Mental status changes

    • Shortness of breath

  • Obtain focused assessment

  • Identify risk factors

 

Sinus Bradycardia: Nursing Process

• Analyze Cues (Analysis)

  • Obtain pulse

  • Interpret ECG

• Prioritize Hypotheses (Analysis)

  • Is the client stable or unstable?

• Generate Solutions (Planning)

  • Is the client’s cardiac output adequate to provide perfusion to the vital organs?

    • Monitor VS

    • Monitor ECG

    • Administer fluids

    • Prepare for pacemaker   

• Take Action (Implementation)

  • Monitor ECG and Vital signs to ensure hemodynamic stability

  • Insert a saline lock in anticipation for administration of IV fluids.

  • Prepare for transcutaneous pacemaker placement if needed

• Evaluate Outcomes (Evaluation)

  • Stabilize the heart rate to over 60 bpm

  • Continuous cardiac monitoring

Sinus Bradycardia: Treatment

• Observe asymptomatic clients

• Unstable clients

  • IV atropine 1 mg repeat every 3-5 minutes not to exceed a total of 3 mg.

  • Monitor for changes in heart rate

  • Temporary transcutaneous pacemaker if client continues to remain unstable and symptomatic

Sinus Tachycardia

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

Sinus Tachycardia: Impact on Overall Health 

• Clients may be asymptomatic or symptomatic.

• Symptoms may include

  • Palpitations

  • Dizziness

  • Lightheadedness

  • Elevated temperature

  • Chest pain

  • Difficulty breathing

• Client could be at risk to fall.

• If symptomatic: decrease physical intensity or activities. Change position slowly.

• Fall precautions:

  • Identify precipitating factors

    • Recent infection or illness

    • Chronic health conditions

    • Stress

    • Pain

    • Anxiety

    • Medications/illicit drugs

• Client education

  • Stress management

  • Discontinue or reduce substances that increase heart rate.

Sinus Tachycardia: Nursing Process

• Assessment (Recognize Cues)

  • Assess for instability

    • Increased respiratory rate

    • Shortness of breath

    • Low blood pressure

    • Changes in level of consciousness

    • Chest pain

    • Decreased urine output

    • dehydration

• Analyze Cues (Analysis)

  • Heart rate

  • ECG

  • Determine hemodynamic stability

• Prioritize Hypotheses (Analysis)

  • Determine the cause of tachycardia

• Generate Solutions (Planning)

  • Ensure adequate perfusion to vital organs

• Take Action (Implementation)

  • Identify underlying cause

  • Teach vasovagal maneuvers

  • Ensure IV lock

• Evaluation of Outcomes (Evaluation)

  • Continue to monitor

Sinus Tachycardia: Treatments and Therapies

• Identify underlying cause of tachycardia

• Interventions to decrease fever, pain, stress fear or anxiety

• Administer Medications as ordered

  • Adenosine

  • Betablockers (metoprolol)

• Catheter Ablation

  • Performed to destroy the abnormally excited cardiac cells responsible for increased heart rate.

Premature Ventricular Contractions (PVCs)

PVCs can be normal and may occur often in healthy clients.

Premature Ventricular Contractions (An example of Bigeminy)

What are the signs and symptoms a client would display if symptomatic with this rhythm?

Premature Ventricular Contractions: Clinical Presentation

• Many clients may be unaware of PVCs

• Clients who are symptomatic will feel palpitations, lightheadedness, chest pain or shortness of breath

• Blood tests cannot identify PVCs but can help identify potential causes for PVCs

  • Potassium

  • Magnesium

  • Thyroid levels

• ECG or Holter monitor to determine cardiac rhythm

Premature Ventricular Contractions: Role of the Nurse

• Assess for contributing factors that increase the likelihood and frequency of PVCs

• Ask client to provide a timeline of manifestations of PVCs

• Obtain a list of medications

• Obtain a list of chronic health conditions

• Analyze the ECG

  • Identify the frequency and pattern of PVCs

• Maintain client safety

• Client teaching to minimize or prevent PVCs

  • Smoking cessation

  • Minimize alcohol

  • Eliminate illicit drug use

  • Reduce caffeine intake

Premature Ventricular Contractions: Nursing Process

• Recognize Cues (Assessment)

  • Assess pulse

  • Auscultation of heart sounds

• Analyze Cues (Analysis)

  • Analyze ECG

  • Analyze client manifestations

  • Review blood test results

• Prioritize Hypotheses (Analysis)

  • Identify potential triggers for causes of PVCs

  • Stabilize the client

• Generate Solutions (Planning)

  • Ensure client’s cardiac output is adequate to perfuse vital organs

  • Frequent monitoring of VS and ECG

  • Prepare for IV electrolyte replacement if indicated

• Take Action (Implementation)

  • Manage contributing factors

    • Smoking

    • Electrolyte imbalance

• Evaluation of Outcomes (Evaluation)

  • Improved

  • Worsened

  • No change

Premature Ventricular Contractions: Treatments and Therapies

• Medications

  • Beta blockers

  • Antiarrhythmic medications

  • Flecainide

  • Propafenone

  • amiodarone

• Catheter Ablation

  • If medications are not effective after 30 days client may be treated with a catheter ablation

Premature Atrial Contractions

• PACs are frequently asymptomatic.

• PACs do not pose a safety risk to the client.

Premature Atrial Contractions: Clinical Presentation

• PACs often discovered on routine physical exam

• Clients usually have no manifestations but may feel fluttering in the chest

• ECG: underlying rhythm is typically normal

• The P wave associated with PAC may be hidden or unidentifiable

• The PR interval associated with PAC may be shortened less than 0.12 or unmeasurable

Premature Atrial Contractions: Role of the Nurse

• Identify lifestyle conditions that are known to precipitate development of PACs

• Provide reassurance to the client

• Lifestyle modifications

• Contact health care provider if palpitations or shortness of breath interfere with activities of daily living.

Premature Atrial Contractions: Nursing Process

• Recognize Cues (Assessment)

  • Obtain a history of chronic medical conditions

  • Obtain list of client medications

  • Gather subjective data regarding manifestations of PACs

• Analyze Cues (Analysis)

  • Analyze ECG to confirm frequency and number of PACs

• Prioritize Hypotheses (Analysis)

  • Identify potential triggers for PACs

• Generate Solutions (Planning)

  • Plan interventions that ensure the client’s cardiac output is adequate to perfuse vital organs

• Take Action (Implementation)

  • Clients typically asymptomatic

  • Provide reassurance

  • Administer beta blockers if indicated

• Evaluate Outcomes (Evaluation)

  • Improved

  • Worsened

  • No change

 

First-Degree Heart Block

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

First-Degree Heart Block: Role of the Nurse

• Identify factors that contribute to first degree heart block

  • Diets high in sodium, cholesterol or triglycerides

• Fall precautions

• Assess vital signs and ECG

• Provide education on lifestyle modification

  • Avoid smoking, alcohol consumption and eat a healthy low-cholesterol diet

  • Avoid excessive fatigue

First-Degree Heart Block: Nursing Process

• Recognize Cues (Assessment)

  • Obtain a thorough past medical history

  • Obtain complete medication list

  • Interpret ECG

  • Auscultate heart sounds

• Analyze Cues (Analysis)

  • Analyze and interpret ECG to measure PR interval

• Prioritize Hypotheses (Analysis)

  • Identify potential triggers for first degree heart block

• Generate Solutions (Planning)

  • Plan interventions to ensure cardiac output is adequate for perfusion to vital organs

  • Hold medications that cause prolonged PR interval

• Take Action (Implementation)

  • Discontinue medications that cause prolonged PR interval

• Evaluate Outcomes (Evaluation)

  • Improve

  • Worsen

  • Stay the same

Atrial Fibrillation

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

Atrial Fibrillation: Clinical Presentation

• Clients may be symptomatic or asymptomatic.

• Symptoms

  • Irregular pulse

  • Hypotension

  • Heart palpitations

  • Increased heart rate

  • Chest discomfort

  • Shortness of breath (at rest or with activity)

  • Exertional fatigue

  • Anxiety

  • Dizziness

  • Lightheadedness

  • Syncope

  • Weight gain

  • Increased urination

• Clinical manifestations may interfere with client’s ability to perform ADLs.

• Safety considerations

  • Client at risk for stroke

  • Risk for spontaneous bleeding

 

Atrial Fibrillation: Laboratory and Diagnostic Testing

• A-fib may be precipitated by hyperthyroidism.

• Blood tests

  • TSH

  • Thyroxine

  • CBC

  • Creatinine

  • Glucose

  • INR

• Echocardiogram: measures the size of the atria and ventricles

• Transesophageal echocardiogram (TEE) detects the development of blood clots in the left atrium.

 

Atrial Fibrillation: ECG Interpretation

• Key diagnostic test to confirm a-fib is an ECG.

• Irregular rhythm

• P waves replaced by atrial activities between QRS complexes

• Ventricular rate can be normal (60 to 100) or increased (100 to 200)

• Rapid heart rate greater than 100/min is referred to as rapid ventricular response

Atrial Fibrillation: Role of the Nurse

• Safety

  • Bleeding precautions for clients on anticoagulant therapy

    • Falls

    • Shaving

    • Vigorous teeth brushing and flossing

    • Participation in contact sports

• Client education

  • Report any manifestations of A-fib to provider

  • Take medications as prescribed

  • Bleeding precautions

  • Healthy lifestyle modifications

  • Avoid stimulants

  • Avoid herbal supplements

Atrial Fibrillation: Nursing Process

• Recognize Cues (Assessment)

  • Obtain a history of manifestations related to A-fib

  • Auscultate heart sounds

  • Obtain blood pressure

  • Palpate pulses

  • Assess for pulse deficit

  • Interpret ECG

• Analyze Cues (Analysis)

  • Interpret ECG

  • Analyze clinical manifestations for potential of clot

• Prioritize Hypotheses (Analysis)

  • Improve cardiac perfusion to prevent complications

• Generate Solutions (Planning)

  • Monitor vital signs

  • Administer antiarrhythmic and anticoagulant medications

  • Plan for client education

• Take Actions (Implementation)

  • Control heart rate and rhythm

  • Prevent blood clot development or dislodgment

  • Avoid herbal supplements, stimulants, smoking and alcohol

• Evaluate Outcomes (Evaluation)

  • Improved

  • Worsened

  • Stay the same

Atrial Fibrillation: Treatments and Therapies

• Interventions for rhythm control

  • Electrocardioversion

  • Catheter ablation

  • Anticoagulants

  • Diet modification

Atrial Flutter

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

Atrial Flutter: Clinical Presentation

• Lightheadedness

• Palpitations

• Hypotension

• Dizziness

• Chest discomfort

• Shortness of breath

Role of the nurse is the same for atrial flutter as it is for a-fib.

Atrial Flutter: Nursing Process

• Recognize Cues (Assessment)

  • Obtain a thorough medical history to identify causative factors

  • Obtain a list of medications

  • Interpret ECG

  • Monitor Vital Signs and O2 Saturation

• Analyze Cues (Analysis)

  • Interpret ECG

  • Analyze ECG findings

• Prioritize Hypotheses (Analysis)

  • Improve cardiac perfusion

  • Prevent potential complications

• Generate Solutions (Planning)

  • Promote cardiac perfusion and prevent complications

  • Plan client teaching to promote prevention of recurrence

• Take Actions (Implementation)

  • Monitor vital signs

  • Administer medications

    • Antiarrhythmics

    • Anticoagulants

  • Prepare for cardioversion

• Evaluate Outcomes (Evaluation)

  • Improve

  • Worsen

  • Stay the Same

Supraventricular Tachycardia

1. Calculate heart rate.

2. Determine if heart rhythm is regular.

3. Assess for P waves.

4. Measure PR interval.

5. Measure duration of QRS complex.

Supraventricular Tachycardia: Clinical presentation

• Manifestations may present suddenly

• Dizziness

• Lightheadedness

• Syncopal episodes

• Hypotension

• Shortness of breath

• Palpitations

• Increased risk of falls

Blood tests are performed to identify underlying chronic medical conditions, such as diabetes, hyperthyroidism, or renal failure.

Supraventricular Tachycardia: Nursing Process

• Recognize Cues (Assessment)

  • Obtain a thorough medial history

  • Interpret ECG findings

  • Assess for manifestations

• Analyze Cues (Analysis)

  • Analyze assessment findings and ECG interpretation

• Prioritize Hypotheses (Analysis)

  • Maintain hemodynamic stability and convert the heart back to normal sinus rhythm

• Generate Solutions (Planning)

  • Promote hemodynamic stability

  • Prevent complications from hypoxia, dyspnea, or hypotension

• Take Actions (Implementation)

  • Monitor heart rate

  • Monitor blood pressure

  • Assist with vagal maneuvers

  • Administer medication

• Evaluate Outcomes (Evaluation)

  • Improve

  • Worsen

  • No change

Supraventricular Tachycardia: Treatment and Therapies

• Vagal maneuvers

• IV adenosine 6 mg IV over 1 to 3 seconds then flush with 20 mL NS

  • If no change give a repeat dose of 12 mg followed by 20 mL NS

  • Adenosine will the heart rate: have a defibrillator on hand

• IV diltiazem

• IV esmolol

• IV metoprolol