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It is a form of cardiac arrhythmia in which ectopic foci within either ventricular or atrial myocardium, or from finer branches of the electric transduction system, cause additional beats of the heart. Some medications may worsen the phenomenon. [citation needed] Ectopic beats are considered normal and are not indicative of cardiac pathology.
Location of the pacemaker can also change its effect on the SA node and its rhythm. An ectopic pacemaker located in the atria is known as an atrial pacemaker and can cause the atrial contraction to be faster. [10] An ectopic pacemaker situated near the AV node and the septum is known as a junctional pacemaker. [11]
Depending whether there are one, two, or three normal (sinus) beats between each PACs, the rhythm is called atrial bigeminy, trigeminy, or quadrigeminy. If 3 or more consecutive PACs occur in a row and at a frequency of 100 or more beats per minute, it may be called atrial tachycardia.
Premature atrial contractions (PACs or APCs) – Normal beats originate in the SA node and extra beats originating from the atria are called PACs. They can be found in normal hearts and be asymptomatic; symptomatic PACs can be treated with beta blockers. PACs, like PVCs, can pair up with normal beats in a pattern called bigeminy.
A premature heart beat or extrasystole [1] is a heart rhythm disorder corresponding to a premature contraction of one of the chambers of the heart. Premature heart beats come in two different types: premature atrial contractions and premature ventricular contractions. Often they cause no symptoms but may present with fluttering in the chest or ...
Cardiac arrhythmias can cause heart block, in which the contractions lose their rhythm. In humans, and sometimes in other animals, a mechanical device called an artificial pacemaker (or simply "pacemaker") may be used after damage to the body's intrinsic conduction system to produce these impulses synthetically.
Premature ventricular contractions may be associated with underlying heart disease, and certain characteristics are therefore elicited routinely: the presence of signs of heart disease or a known history of heart disease (e.g. previous myocardial infarction), as well as heart disease or sudden cardiac death in close relatives.
Yet heart problems often produce no symptoms until very advanced, and many symptoms, such as palpitations and sensations of extra or missing heart beats correlate poorly with relative heart health vs disease. Hence, a history alone is rarely sufficient to diagnose a heart condition.