ECG Rhythms and other helpful tools
Rhythm ECG Characteristics Strip Example
1. Normal sinus P Wave: YES
Rhytm (NSR) PR Interval: 0.12-0.20
sec
QRS: 0.06-0.10 sec
Rate: 60-100 bpm
Regularity: Regular
2. Sinus P Wave: YES
Bradycardia PR Interval: 0.12-0.20
Causes: sec
Intrinsic sinus node QRS: 0.06-0.10 sec
disease
Rate: < 60 bpm
Increased
parasympathetic Regularity: Regular
tone
Drug effect
3. Sinus P Wave: YES
Tachycardia PR Interval: 0.12-0.20
Causes: sec
Exercise QRS: 0.06-0.10 sec
Hypovolemia Rate: > 100 bpm
Medications
Feber
Regularity: Regular
Hypoxia
Substances
Anxiety, Fear
Acute MI
Fight or Flight
Congestive Heart
Failure
Rhythm ECG Characteristics Strip Example
4. SR wPACs P Wave: YES, early &
(Premature atrial complexes) upright, different from
Causes:
Normal
Sinus
Excessive use of PR Interval: 0.12-0.20
caffeine, tobacco, sec
or alcohol QRS: 0.06-0.10 sec
CHF Rate: < 100 bpm
Myocardial dependent on underlying
ischemia or injury
rhythm
Hypokalemia, Dig
toxicity Regularity: irregular
COPD
5. SR wPVCs P Wave: usually absent
(Premature atrial complexes) not present
Causes:
Gastric overload
PR Interval: follows the
Stress underlying rhythm, but in
Caffeine, Alcohol, the early complex no P
Nicotine wave is present
Heart Disease QRS: 0.06-0.10 sec
Acid-Base underlying, with 0.12 sec
Imbalance
or greater; bizarre and
Electrolyte
Imbalance notched
Cyclic Rate: dependent on
Antidepressants underlying rhythm
Hypoxia Regularity:
Acidosis
Acute MI
6. Atrial P Wave: not identifiable
Fibrillation PR Interval: not
Causes: measurable
Ischemic heart QRS: 0.06 – 0.10 sec
disease
Rate: Atrial: 400-700
Hypoxia
Acute MI
bpm Ventricle: 160-180
Digitalis toxicity bpm
Mitral or tricuspid Regularity: irregular
disease
Rhythm ECG Characteristics Strip Example
7. Atrial Flutter P Wave: not identifiable
Causes: PR Interval: not
Ischemic heart measurable
disease
QRS: 0.06-0.10sec
Hypoxia
Acute MI
Rate: Atrial: 250-350
Dig Toxicity bpm Ventricle: 150
Mitral or Tricuspid common
valve disease Regularity: Atrial:
Pulmonary regular Ventricle: regular
embolism or irregular
8. Ventricular P Wave: not identifiable
Tachycardia PR Interval: not
(VTACH) measurable
Causes: QRS: > 0.12 sec; wide
Hypoxia and bizarre appearance
Electrolyte
Rate: > 100 bpm
imbalance
Cardiomyopathy Regularity: regular but
ischemic heart may be irregular at times
disease
9. Ventricular P Wave: not identifiable
Fibrillation PR Interval: not
(VFIB) measurable
Causes: QRS: no uniform
Check patient first appearnce
Check poorly
Rate: not
attached leads
Emergency identifiable/measurable
situation Regularity: irregular and
Congenital heart chaotic
disease
Cardiomyopathy
Previous heart
attack
Rhythm ECG Characteristics Strip Example
10. Asystole P Wave: not identifiable
Causes: PR Interval: not
Hypovolemia measurable
Hypoxia QRS: not
Acidosis
Hypothermia
identifiable/measurable
Hyperkalemia or Rate: not measurable
Hypokalemia Regularity: “straight
Hypoglycemia line” or “flat line”
drug overdose
Electric shock
Tachycardia
Cardiac
Tamponade
Tension
pneumothorax
MI
Pulmonary
embolism
Trauma
(hypovolemia from
blood loss)
11. SVT P Wave:
Supraventricular PR Interval: not
Tachycardia
An umbrella term used measurable/visible
when unable to QRS: 0.06-0.10 sec
distinguish which Rate: > 150 bpm
rhythm is present Regularity: regular or
Causes:
Same as Sinus,
minimal irregularity
Atrial, and
Junctional
Tachycardia, and
Atrial Flutter
12. Atrial P Wave:
Pacemaker PR Interval:
Causes: QRS:
Pacemaker delivers Rate:
atrial pacing, the
pacing spike will
Regularity:
be followed by a P
wave.
Rhythm ECG Characteristics Strip Example
13. Ventricular P Wave:
Pacemaker PR Interval:
Causes: QRS:
pacemaker delivers Rate:
ventricular pacing,
the pacing spike
Regularity:
will be followed by
a wide QRS
complex,
14. AV Pacemaker P Wave:
Causes: PR Interval:
AV sequential QRS:
pacemaker tracing
has an
Rate:
atrioventricular Regularity:
delay
An atrioventricular
delay is similar to
the measurement of
the PR interval on a
normal rhythm
tracing.
It is measured from
the atrial spike to
the ventricular
spike.
Cardiac Conduction. (1) The sinoatrial (SA) node and the
remainder of the conduction system are at rest. (2) The SA node
initiates the action potential, which sweeps across the atria. (3)
After reaching the atrioventricular node, there is a delay of
approximately 100 ms that allows the atria to complete pumping
blood before the impulse is transmitted to the atrioventricular
bundle. (4) Following the delay, the impulse travels through the
atrioventricular bundle and bundle branches to the Purkinje
fibers, and also reaches the right papillary muscle via the
moderator band. (5) The impulse spreads to the contractile fibers
of the ventricle. (6) Ventricular contraction begins.
5 Step Procedure (1 small box = 0.04 seconds; 5 small box = 0.20 seconds; 5 large box = 1 second)
1. Is there a P wave for every QRS
2. Regular / Irregular (count R waves time 10 for heartrate)
3. What is measurement of PR interval
4. What is measurement of QRS
5. Interpret the rhythm
Interpretation-TIPs
PR Interval: The smallest unit of measure for determining measurements is one-half of a small box. Remember, one small box represents 0.04 second.
One half of 0.04 second is 0.02 second. When analyzing a rhythm tracing, you can measure to the nearest whole or one-half of a small box. Smaller
measurements are not possible with the human eye; only a computer can read less than one-half of a box accurately. Therefore, the time interval you
record should always be in multiples of 0.02 second.
QRS Measurement: Although a QRS measurement of 0.11 second is still considered within the normal range, this measurement can be provided only
by an ECG machine. The human eye cannot discern less than 0.5 mm measurements.
1. Normal Sinus Rhythm
a. Sinus rhythm is the only rhythm for which all five steps are within nor-mal limits.
2. Sinus Bradycardia
a. In sinus bradycardia, the heart rate is less than 60 beats per minute, and all other measurements are within normal limits.
3. Sinus Tachycardia
a. In sinus tachycardia, the heart rate is greater than 100 beats per minute, and all other measurements are within normal limits.
4. Premature Atrial Complexes
a. A PAC is a cardiac complex that occurs too soon. It has a positively deflected P wave. Other than being “early,” this complex does not possess
any abnormal features.
5. Premature Ventricular Complexes
a. A PVC is an early QRS complex that measures 0.12 second or greater and has a wide and bizarre appearance. There is no P wave.
6. Atrial Fibrillation
a. Atrial fibrillation shows chaotic atrial electrical activity with irregular R-R intervals.
7. Atrial Flutter
a. Atrial flutter has a “saw tooth” atrial pattern between the QRS complexes.
8. Ventricular Tachycardia (VTACH)
a. Ventricular tachycardia has wide and bizarre QRS complexes with a classic “saw tooth” appearance, a rate in excess of 100 beats per minute, and
no P waves.
9. Ventricular Fibrillation (VFIB)
a. Ventricular fibrillation is the absence of organized electrical activity. The tracing is disorganized or chaotic in appearance.
10. Asystole
11. Supraventricular tachycardia
a. Supraventricular tachycardia describes a group of dysrhythmias that present with a normal-to-narrow QRS complex and a rate of greater than 150
beats per minute.
12. Atrial Pacemaker
a. Pacemaker rhythms are distinguished by the conspicuous presence of a spike prior to the waveform of the portion of the heart that is being paced.
For example, a spike before the P wave indicates that the pace-maker is pacing the atrial portion of the depolarization.
13. Ventricluar Pacemaker
14. AV Pacemaker
