Term
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Definition
| disorder of the formation or conduction (or both) of the electrical impulse within the heart, cause disturbances of heart rate, rhythm or both |
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Term
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Definition
| near superior vena cava in the right atrium |
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Term
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Definition
| electrical stimulation, systole |
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Term
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Definition
| electrical relaxation, diastole |
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Term
| sympathetic nervous system stimulation |
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Definition
Increases:
1.) heart rate (positive chonotropy),
2.) conduction through AV node (positive dromotropy) 3.)force of myocardial contraction (positive inotropy) 4.)increases BP |
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Term
| parasympathetic nervous system stimulation |
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Definition
Reduces:
1.) HR (neg. chonotropy)
2.) AV conduction (positive dromotropy)
3.) force of atrial myocardial contraction
4.) vasodilation- lowers BP |
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Term
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Definition
atrial depolarization-represents electrical impulse starting in sinus node and spreading through atria
- 2.5 mm or less in height, 0.11 seconds or less in duration |
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Term
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Definition
ventricular depolarization- usually less than 0.12 seconds in duration (atrial repolarization occurs at same time, not visible on ECG)
- Q wave is first negative deflection after P wave, normally less than 0.04 seconds in duration and less than 25% or the R-wave amplitude
- R wave is first positive deflection
- S wave is first negative deflection after R wave |
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Term
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Definition
| ventricular repolarization (resting state |
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Term
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Definition
represents repolarization of Purkinje fibers
- seen in patients with hypokalemia, hypertension, heart disease |
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Term
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Definition
measured from beginning of the P wave to beginning of QRS complex
- represents time needed for sinus node stimulation, atrial depolarization, and conduction through AV node before ventricular depolarization |
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Term
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Definition
represents early ventricular repolarization, lasts from end of QRS complex to beginning of T wave
- may be sign of cardiac ischemia |
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Term
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Definition
represents total time for ventricular depolarization and repolarization, measured from beginning of QRS complex to end of T wave
- prolonged=at risk for lethal ventricular dysrhythmia- torsades de pointes |
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