Lab 3: ECG interpretation
Common Basic Cardiac Rhythms
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Normal sinus rhythm
○ Rhythm Characteristics:
■ Regular rhythm
■ Rate: 60 - 100 bpm
■ Normal PQRST complex
○ Appearance:
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Clinical significance:
■ Normal heart rate and rhythm
Sinus Tachycardia
○ Rhythm Characteristics:
■ Regular rhythm
■ Rate: 100 - 180 bpm
■ Normal P wave, PR interval, and QRS complex
○ Appearance:
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Clinical Significance:
■ Normal response to exercise, emotion, pain, fever, hyperthyroidism, and certain
drugs
Sinus bradycardia
○ Rhythm Characteristics:
■ Regular rhythm
■ Rate: <60 bpm
■ Normal P wave, PR interval, and QRS complex
○ Appearance:
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Clinical Significance:
■ Associated with decreased cardiac output, dizziness, syncope, and chest pain
Premature ventricular Contractions
○ Rhythm Characteristics:
■ Rhythm irregular
■ Compensatory pause
○ Appearance:
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○ Clinical Significance:
■ Caused by irritable focus; if more than 6 beats/min or in pairs, indicates
increased ventricular irritability: usually benign, not requiring treatment
○ Types (in terms of foci) - Observe the PVCs in terms of size and orientation
(inverted/upside down/looks different to one another/etc)
■ Multifocal (diff foci): Different shape
■ Unifocal (same foci): Same shape
○ Types (in terms of pattern)
■ Couplet: two PVCs together or right after one another
■ Bigeminy: Every second beat, there’s a PVC
■ Trigeminy: Every Third beat, there’s a PVC
○ VTach can occur if 3+ consecutive PVCs occur
Ventricular Tachycardia:
○ Rhythm Characteristics:
■ Regular slightly irregular
■ Rate: 100 - 200 beats per mn
■ P wave absent, QRS complex wide and bizarre
○ Appearance:
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Clinical Significance:
■ Often a forerunner of ventricular fibrillation; may cause pulselessness; if patient is
unstable or pulseless, requires electrical defibrillation as soon as possible
○ Types:
■ Sustained: Monomorphic
■ Unsustained: Polymorphic
■ There is also Torsades de pointes
Ventricular Fibrillation
○ Rhythm Characteristics:
■ Chaotic rhythm with no identifiable waves
■ Can’t identify the rate
○ Appearance:
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Clinical Significance:
■ Lethal arrhythmia; patient pulseless and requires electrical defibrillation or shock
as soon as possible filled by immediate CPR
Types:
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■
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Coarse VF: Waves are more easily visible (greater than 3 mm)
Fine VF: Low amplitude waves (less than 3 mm)
Asystole
○ Rhythm Characteristics:
■ Flat line
■ No waves
■ Usually preceded by severe bradycardia
○ Appearance:
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Clinical Significance:
■ Lethal arrhythmia; no pulse, begin immediate CPR unless patient has a DO NOT
RESUSCITATE (DNR) order; if a DNR order is present, do not begin CPR
Obtaining a 12-Lead Electrocardiogram
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Electrical impulses of the heart are conducted to the surface of the body and are detected by
electrodes placed on the skin of the limbs and torso.
One electrode is placed on each of the four extremities, and six electrodes are placed at specific
sites of the chest for a total of 10 electrodes on the patient’s skin.
Bipolar limb leads: I, II, III,
Augmented limb leads: aVR, aVL, aVF
Precordial chest leads: V1, V2, V3, V4, V5, V6
The leads view a specific part of the surface of the heart and can help determine which part of the
heart has sustained damage and the origin and flow of the impulse.
Assessment:
1. Identify patient using at least two identifiers (e.g., name and birthday or name and medical record
number) according to agency policy
2. Determine indications for obtaining ECG. Assess patient’s history and cardiopulmonary status
(e.g., heart rate and rhythm, blood pressure, respirations)
3. Assess for chest pain; rate acuity on a scale of 0 to 10.
4. Assess patient’s level of understanding of procedure, including any concerns
5. Assess patients ability to follow directions and remain still in supine position
Nursing Diagnosis:
● Acute pain
● Anxiety
● Deficient knowledge regarding purpose and steps of procedure
● Fear
Planning:
1. Expected outcomes following completion of procedure:
a. Patient tolerates procedure without anxiety or discomfort
b. Clear, accurate recording of ECG waveform is obtained
2. Close room door or bedside curtains.
Implementation:
1. Prepare patient for procedure:
a. Remove or reposition the patient's clothing to expose only the patient's chest and arms.
Keep the abdomen and thighs covered.
b. Place patient in supine position with head of bed no higher than 30 degrees
c. Instruct patient to lie still without talking and do not cross legs
2. Turn on machine; enter required demographic information
3. Perform hand hygiene
4. Clean and prepare skin for isolated electrode placement with soap and water. Wipe the area with
a rough washcloth or gauze or use the edge of the electrode to gently scrape skin. Clip excessive
hair from the electrode area.
5. Apply electrodes in correct positions. If using leads with suction cups, apply electrode paste to
areas before attaching leads.
a. Chest
i.
V1 - 4th intercostal space at right sternal border
ii.
V2- 4th intercostal space at left sternal border
iii.
V3 - Midway between V2 and V4
iv.
V4 - 5th intercostal space at midclavicular line
v.
V5 - Left anterior axillary line at level of V4 horizontally
vi.
V6 - Left midaxillary line at level of V4 horizontally
b. Extremities
i.
Right arm - White electrode
ii.
Left arm - Black electrode
iii.
Right leg - Green electrode
iv.
Left leg - Red electrode
6. Check the 12-lead machine for messages to correct electrode or lead issues. If no message
occur, press button to obtain 12-lead ECG
7. If you obtain ECG tracing without artifact, disconnect leads and wipe off excess electrode paste
from chest
8. If STAT, immediately deliver ECG tracing (if not computerized) to appropriate health care provider
for interpretation.