الفهرس 
Anatomy and Physiology of Conduction SystemOnly 14 pages are availabe for public view
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Abstract
The cardiac impulses are initiated and propagated
through specialized conduction system within the heart.
Despite spontaneous beating, heart rate is influenced by
autonomic nervous system (ANS) and other factors. The
heart beats in an orderly predetermined sequence, when this
sequence disturbs, cardiac arrhythmias are the result.
The mechanisms of cardiac arrhythmias are generally
divided into two categories; disorders of impulse formation
(altered automaticity and triggered activity), disorders of
impulse conduction (reentry and blocks), or combinations of
both.
Cardiac arrhythmias are usually divided based on
heart rate into; Tachyarrhythmias (e.g., AF, atrial flutter,
ventricular arrhythmias, and other supraventricular
tachycardias); Bradyarrhythmias (e.g., junctional rhythm,
sinus bradycardia, and AV conduction block).
The treatment of cardiac arrhythmias can be either;
pharmacological (i.e. antiarrhythmic drugs) or
nonpharmacogical (e.g. cardioversion, defibrillation,
external and internal pacing devices, vagal maneuver or
even cardiac surgery).
Summary
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Postoperative arrhythmias are common and represent
a major source of morbidity after both cardiac and
noncardiac surgical procedures. Although noncardiac
surgeries have a lower incidence of arrhythmias than cardiac
surgeries, disease burden is higher due to number of
surgeries performed. The majority of these arrhythmias are
supraventricular in origin. AF is the single most common
arrhythmia encountered.
The pathophysiology of cardiac arrhythmias in the
postoperative setting is complex. Stress response to surgery
and activation of inflammatory pathways are the mainly
suspected mechanisms. Although several preoperative risk
factors have been identified for postoperative arrhythmias,
advanced age is the most consistent risk factor seen in the
studies. Also, other factors related to surgery and anesthesia
may play a role.
ECG and rapid clinical assessment are the basic tools
for diagnosis. A 12-lead ECG with a long rhythm strip and a
previously obtained 12-lead ECG for comparison are ideal.
But wave forms visible on the telemonitor or a rhythm strip
in one lead tracing may be the only available clue.
No large scale randomized trials validating the
treatment of post noncardiac surgery arrhythmias are