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Sinus RhythmsSinus RhythmsChapter 13Chapter 13
Normal Sinus RhythmNormal Sinus Rhythm
Autonomic Nervous System
Sympathetic nerves
Parasympathetic nerves (vagus nerve)
Autonomic Nervous System
Sympathetic nerves
Parasympathetic nerves (vagus nerve)
Sympathetic StimulationSympathetic Stimulation
Increase in HR
Palpitations
pounding
normal, premature beats, or ectopic (non-sinus) beats,
Increase in HR
Palpitations
pounding
normal, premature beats, or ectopic (non-sinus) beats,
TachycardiaTachycardia
HR exceeding 100 beats/min
Increase SNS and/or decrease in PNS
Elderly individuals rarely show HR greater than 140-150 bpm
HR above this range usually indicate non-sinus tachycardia (e.g. atrial fibrillation or a paroxysmal supraventricular tachycardia)
HR exceeding 100 beats/min
Increase SNS and/or decrease in PNS
Elderly individuals rarely show HR greater than 140-150 bpm
HR above this range usually indicate non-sinus tachycardia (e.g. atrial fibrillation or a paroxysmal supraventricular tachycardia)
Sinus TachycardiaSinus Tachycardia
• P Wave - Visible before each QRS complex• P-R Interval - Normal• QRS Duration - Normal• Rhythm - Regular• Rate - More than 100 beats per minute
• P Wave - Visible before each QRS complex• P-R Interval - Normal• QRS Duration - Normal• Rhythm - Regular• Rate - More than 100 beats per minute
TachycardiaTachycardia
Each QRS complex is preceded by a P wave
With a very fast rate, the P wave may merge with the preceding T wave
Each QRS complex is preceded by a P wave
With a very fast rate, the P wave may merge with the preceding T wave
TachycardiaTachycardiaAnxiety, exertion, pain,
Drugs: increase SNS or decrease vagal tone
Fever
Congestive heart failure
Pulmonary embolism
Acute MI
Hyperthyrodism
Pheochromocytoma
Blood loss
Alcohol intoxication
Anxiety, exertion, pain,
Drugs: increase SNS or decrease vagal tone
Fever
Congestive heart failure
Pulmonary embolism
Acute MI
Hyperthyrodism
Pheochromocytoma
Blood loss
Alcohol intoxication
Sinus BradycardiaSinus Bradycardia
Heart rate less than 60 bpmHeart rate less than 60 bpm
Sinus BradycardiaSinus Bradycardia
P Wave - Visible before each QRS complex
P-R Interval - Normal
QRS Duration - Normal
Rhythm - Regular
Rate - less than 60 beats per minute
Usually benign and often caused by patients on beta blockers
P Wave - Visible before each QRS complex
P-R Interval - Normal
QRS Duration - Normal
Rhythm - Regular
Rate - less than 60 beats per minute
Usually benign and often caused by patients on beta blockers
Sinus BradycardiaSinus Bradycardia
Normal variant
Drugs: decrease SNS or increase vagal tone
Hypothyroidism
Hyperkalemia
Sick sinus syndrome (Fig 13-5)
Sleep apnea
Carotid sinus hypersensitivity syndrome
Vasovagal reactions
Normal variant
Drugs: decrease SNS or increase vagal tone
Hypothyroidism
Hyperkalemia
Sick sinus syndrome (Fig 13-5)
Sleep apnea
Carotid sinus hypersensitivity syndrome
Vasovagal reactions
Sinus BradycardiaSinus Bradycardia
Symptoms
Moderate sinus bradycardia produces no symptoms
If HR is very slow, lightheadedness and syncope
Symptoms
Moderate sinus bradycardia produces no symptoms
If HR is very slow, lightheadedness and syncope
Sinus ArrhythmiaSinus Arrhythmia
Beat to beat variation in HR
Younger, healthy individuals
Common cause: respiration
Respiratory sinus arrhythmia
Beat to beat variation in HR
Younger, healthy individuals
Common cause: respiration
Respiratory sinus arrhythmia
Sinus Pauses/Sinus ArrestSinus Pauses/Sinus Arrest
SA fails to stimulate the atria
Sinus pause or sinus arrest (Fig. 13-5)
SA fails to stimulate the atria
Sinus pause or sinus arrest (Fig. 13-5)
Escape BeatsEscape Beats
Escape beat (Fig. 13-6)
Atria, AV node or ventricles
Escape beat (Fig. 13-6)
Atria, AV node or ventricles
Sinus Pauses/Sinus ArrestSinus Pauses/Sinus Arrest
Causes of sinus pause or arrest
hypoxemia
Ischemia or MI
Hyperkalemia
Drug toxicity
Vagal hyperreactivity
Sick sinus syndrome (Fig 13-5)
Causes of sinus pause or arrest
hypoxemia
Ischemia or MI
Hyperkalemia
Drug toxicity
Vagal hyperreactivity
Sick sinus syndrome (Fig 13-5)
