EKG interpretation - ANS One of the most useful and commonly used diagnostic tools is
electrocardiography (EKG) which measures the heart's electrical activity as waveforms. An EKG
uses electrodes attached to the skin to detect electric current moving through the heart. These
signals are transmitted to produce a record of cardiac activity. Arrhythmia or dysrhythmia are
disturbances in the normal cardiac rhythm of the heart which occurs as a result of alterations
within the conduction of electrical impulses. These impulses stimulate and coordinate atrial and
ventricular myocardial contractions that provide cardiac output.
Sinus Tachycardia - ANS Sinus tachycardia is a heart rate greater than 100 beats per minute
that originated from the sinus node.
Rate: 100 to 180 beats per minute
P Waves precede each QRS complex
PR interval is normal
QRS complex is normal
Conduction is normal
Rhythm is regular
Causes of sinus tachycardia may include exercise, anxiety, fever, drugs, anemia, heart failure,
hypovolemia and shock. Sinus tachycardia is often asymptomatic. Management however is
directed at the treatment of the primary cause. Carotid sinus pressure (carotid massage) or a
beta blocker may be used to reduce heart rate.
Sinus Bradycardia - ANS Sinus bradycardia is a heart rate less than 60 beats per minute and
originates from the sinus node (as the term "sinus" refers to sinoatrial node). It has the following
characteristics
Rate is less than 60 beats per minute
P Waves precede each QRS complex
PR interval is normal
QRS complex is normal
Conduction is normal
Rhythm is regular
Causes may include drugs, vagal stimulation, hypoendocrine states, hypothermia, or sinus node
involvement in MI. This arrhythmia may be normal in athletes as they have quality stroke
volume. It is often asymptomatic but manifestations may include: syncope, fatigue, dizziness.
Management includes treating the underlying cause and administering anticholinergic drugs like
atropine sulfate as prescribed.
Premature Atrial Contraction - ANS Premature Atrial Contraction are ectopic beats that
originates from the atria and they are not rhythms. Cells in the heart starts to fire or go off before
the normal heartbeat is supposed to occur. These are called heart palpitations and has the
following characteristics:
Premature and abnormal-looking P waves that differ in configuration from normal P waves
QRS complex after P waves except in very early or blocked PACs
P waves often buried in the preceding T wave or identified in the preceding T wave.
Causes includes coronary or valvular heart diseases, atrial ischemia, coronary artery
atherosclerosis, heart failure, COPD, electrolyte imbalance and hypoxia. Usually there is no