Term
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Definition
| -any deviation from the normal electrical rhythm of the heart |
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Term
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Definition
| -the absence of cardiac electrical activity |
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Term
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Definition
-myocardial ischemia, necrosis or infarction
-autonomic nervous system imbalance
-distention of the chambers of the heart (especially the atria, secondary to congestive heart failure)
-blood gas abnormalities, including hypoxia and abnormal pH
-electrolyte imbalances
-trauma to the myocardium
-drug effects and drug toxicity
-electrocution
-hypothermia
-CNS damage
-idiopathic events
-normal ocurrences |
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Term
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Definition
| -nonpacemaker heart cell that automatically depolarizes |
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Term
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Definition
-cardiac depolarization resulting from depolarization of ectopic focus
-PVC's, PJC's and PAC's |
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Term
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Definition
-may cause isolated premature beats or tachydysrhythmias
-occurs when ischemia or another disease process alters two branches of a conduction pathway, slowing conduction in one branch and causing a unidirectional block in the other
-PSVT or A-Fib |
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Term
| Classification of dysrhythmias |
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Definition
-nature of origin (changes in automaticity vs. disturbances in conduction)
-magnitude (major vs. minor)
-severity (life threatening vs. non-life threatening)
-site of origin |
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Term
| Classifying dysrythmias by site of origin |
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Definition
-originating in the SA node
-originating in the atria
-originating withing the AV junction
-sustained in or originating in the AV junction
-originating in the ventricles
-resulting from disorders of conduction |
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Term
| Dysrythmias originating in the SA node |
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Definition
-most often result from changes in autonomic tone
-disease can exist in the SA node
*sinus bradycardia
*sinus tachycardia
*sinus dysrythmia
*sinus arrest
*sinus block
*sinus pause
*sick sinus syndrome |
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Term
| Sinus bradycardia rules of interpretation |
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Definition
-Rate = less than 60
-Rhythm = regular
-Pacemaker site = SA node
-P waves = upright and normal in morphology
-PR interval = normal
-QRS complex = normal |
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Term
| Sinus bradycardia etiology and clinical significance |
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Definition
-Etiology
*increased parasympathetic tone
*intrinsic disease of the SA node
*drug effects (digitalis, propranolol, quinidine)
*normal finding in healthy, well-conditioned persons
-Clinical significance
*decreased Hr can cause decreased cardiac output, hypotension, angina or CNS symptoms
*may also lead to atrial ectopic or ventricular ectopic rhythms. |
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Term
| Sinus bradycardia treatment |
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Definition
-generally unnecessary unless signs of poor perfusion
-for poor perfusion:
*prepare for TCP
*consider Atropine |
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Term
| Sinus tachycardia rule of interpretation |
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Definition
-Rate = greater than 100
-Rhythm = regular
-Pacemaker site = SA node
-P waves = upright and normal in morphology
-PR interval = normal
-QRS complex = normal |
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Term
| Sinus tachycardia etiology and clinical significance |
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Definition
-Etiology
*exercise
*fever
*anxiety
*hypovolemia
*anemia
*pump failure
*increased sympathetic tone
*hypoxia
*hyperthyroidism
-Clinical significance
*often benign
*very rapid rates increase myocardial oxygen demand
*can precipitate ischemia or infarct in diseased hearts |
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Term
| Sinus tachycardia treatment |
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Definition
| -directed at underlying cause |
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Term
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Definition
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Term
| Sinus dysrhythmia rules of interpretation |
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Definition
-Rate = 60-100 (varies with respirations)
-Rhythm = irregular
-Pacemaker site = SA node
-P waves = upright and normal in morphology
-PR interval = normal
-QRS complex = normal |
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Term
| Sinus dysrhythmia etiology and clinical significance |
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Definition
-Etiology
*often a normal finding, sometimes related to respiratory cycle
*can be caused by enhanced vagal tone
-Clinical significance
*normal variant particularly in young and elderly |
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Term
| Sinus dysrhythmia treatment |
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Definition
| -typically, none required |
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Term
| Sinus arrest/block/pause rules of interpretation |
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Definition
-Rate = normal to slow, depending on frequency and duration of the arrest
-Rhythm = irregular
-Pacemaker site = SA node
-P waves = upright and normal in morphology
-PR interval = normal
-QRS complex = normal |
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Term
| Sinus arrest/block/pause etiology and clinical significance |
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Definition
-Etiology
*can result from:
-ischemia of the SA node
-digitalis toxicity
-excessive vagal tone
-degenerative fibrotic disease
-Clinical significance
*frequent or prolonged episodes may compromise cardiac output resulting in syncope or other problems
*always danger of complete cessation of SA node activity
*usually an escape rhythm develops |
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Term
| Sinus arrest/block/pause treatment |
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Definition
-if asymptomatic, observation required unless signs of poor perfusion are present
-if poorly perfusing:
*consider Atropine
*prepare for TCP |
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Term
| Sick sinus syndrome rules of interpretation |
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Definition
-Rate = extremely variable
-Rhythm = irregular
-Pacemaker site = SA node
-P waves = upright and normal in morphology
-PR interval = normal
-QRS complex = normal |
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Term
| Sick sinus syndrome etiology and clinical significance |
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Definition
-Etiology
*ischemia of the SA node
*digitalis toxicity
*degenerative fibrotic disease
-Clinical significance
*frequent or prolonged episodes may compromise cardiac output, resulting in syncope
*always danger of complete cessation of SA activity
*usually an escape rhythm develops |
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Term
| Sick sinus syndrome treatment |
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Definition
-if asymptomatic, observation is all that's required, unless perfusing poorly
-if poor perfusion:
*begin TCP |
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