NORMAL SINUS RHYTHM
Definition Reflects normal conduction of the sinus impulse through the atria and ventricles
Rate Atrial and ventricular rates are the same and range from 60–100 bpm
Rhythm Rhythm is regular or essentially regular
P Wave Normal
PR Interval Normal
QRS Complex Normal
QT Interval Normal
T Wave Normal
Conduction Normal
Causes Occurs in healthy cardiac systems
Symptoms No symptoms; patient is hemodynamically stable
Medication None required
Treatment None required
Distinguishing N/A
feature
, SINUS TACHYCARDIA
Definition Sinus tachycardia results when the SA node fires faster than 100 bpm. It is a normal
response to stimulation of the sympathetic nervous system
Rate Both atrial and ventricular rate >100 bpm, my even be as fast as 180 bpm
Rhythm Gradual onset; Regular or essentially regular
P Wave Normal; may be hidden in T wave is rate is too fast
PR Interval Normal
QRS Complex Normal
QT Interval May shorten
T Wave Normal; may overcome the P waves in rapid rates
Conduction Normal
Causes Hyperthyroidism, hypovolemia, HF, anemia, exercise, use of stimulants, fever,
sympathetic response to fear/pain, anxiety, inotropic meds, caffeine
Symptoms HR may CO d/t shorter filling times for the ventricles
Medication None specifically (antipyretics if caused by fever, pain medication if caused by pain)
Treatment Tx depends on context (Sinus tachy may be a normal response). Treat underlying
cause (ceasing/starting medication, replacing blood or fluids, etc.)
Distinguishing This is a normal fast rate. P’s may not be present and that’s ok, they may just be
feature hiding within a T wave
, SINUS BRADYCARDIA
Definition Sinus bradycardia may be normal for athletes or may occur during sleep. Although
this may be asymptomatic, it may cause instability. Assess for instability in pt
Rate Both atrial and ventricular rates <60 bpm
Rhythm Regular or essentially regular
P Wave Normal
PR Interval Normal
QRS Complex Normal
QT Interval Might be prolonged
T Wave Normal
Conduction Decreased in SA node (looks like NSR but at a slower rate)
Causes [Normal in athletes and during sleep] ICP, hypoxia, hypothermia, heart disease,
excessive inhibitory vagal (vomiting, BM), drug induced (digoxin, Inderal), Ca
channel blockers, Beta Blockers
Symptoms A slowed heart rhythm may cause a decrease in CO, resulting in hypotension and
decreased organ perfusion; changes in LOC, chest discomfort, SOB/resp. distress,
pulmonary congestion/crackles, rapid/slow/weak pulse, dizziness, syncope, fatigue,
restlessness
Medication Atropine (IVP, most common drug for low HR, one-time dose); Isuprel (IV drip, cont.
infusion, not a permanent fix)
Treatment None if mild; observation; pacing/pacemaker
Distinguishing A normal slow
feature
Definition Reflects normal conduction of the sinus impulse through the atria and ventricles
Rate Atrial and ventricular rates are the same and range from 60–100 bpm
Rhythm Rhythm is regular or essentially regular
P Wave Normal
PR Interval Normal
QRS Complex Normal
QT Interval Normal
T Wave Normal
Conduction Normal
Causes Occurs in healthy cardiac systems
Symptoms No symptoms; patient is hemodynamically stable
Medication None required
Treatment None required
Distinguishing N/A
feature
, SINUS TACHYCARDIA
Definition Sinus tachycardia results when the SA node fires faster than 100 bpm. It is a normal
response to stimulation of the sympathetic nervous system
Rate Both atrial and ventricular rate >100 bpm, my even be as fast as 180 bpm
Rhythm Gradual onset; Regular or essentially regular
P Wave Normal; may be hidden in T wave is rate is too fast
PR Interval Normal
QRS Complex Normal
QT Interval May shorten
T Wave Normal; may overcome the P waves in rapid rates
Conduction Normal
Causes Hyperthyroidism, hypovolemia, HF, anemia, exercise, use of stimulants, fever,
sympathetic response to fear/pain, anxiety, inotropic meds, caffeine
Symptoms HR may CO d/t shorter filling times for the ventricles
Medication None specifically (antipyretics if caused by fever, pain medication if caused by pain)
Treatment Tx depends on context (Sinus tachy may be a normal response). Treat underlying
cause (ceasing/starting medication, replacing blood or fluids, etc.)
Distinguishing This is a normal fast rate. P’s may not be present and that’s ok, they may just be
feature hiding within a T wave
, SINUS BRADYCARDIA
Definition Sinus bradycardia may be normal for athletes or may occur during sleep. Although
this may be asymptomatic, it may cause instability. Assess for instability in pt
Rate Both atrial and ventricular rates <60 bpm
Rhythm Regular or essentially regular
P Wave Normal
PR Interval Normal
QRS Complex Normal
QT Interval Might be prolonged
T Wave Normal
Conduction Decreased in SA node (looks like NSR but at a slower rate)
Causes [Normal in athletes and during sleep] ICP, hypoxia, hypothermia, heart disease,
excessive inhibitory vagal (vomiting, BM), drug induced (digoxin, Inderal), Ca
channel blockers, Beta Blockers
Symptoms A slowed heart rhythm may cause a decrease in CO, resulting in hypotension and
decreased organ perfusion; changes in LOC, chest discomfort, SOB/resp. distress,
pulmonary congestion/crackles, rapid/slow/weak pulse, dizziness, syncope, fatigue,
restlessness
Medication Atropine (IVP, most common drug for low HR, one-time dose); Isuprel (IV drip, cont.
infusion, not a permanent fix)
Treatment None if mild; observation; pacing/pacemaker
Distinguishing A normal slow
feature
