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WVSOM - Physio
Arrythmias
| Question | Answer |
|---|---|
| Arrhythmia | an abnormality of impulse initiation, impulse conduction or both |
| Normal automaticity | arrhythmias associated with normal automatic pacemakers |
| abnormal automaticity | arrhythmias associated with non pacemaker cells that develop automaticity |
| triggered activity | oscillations in membrane potential that trigger an action potential |
| Normal SAN pacemaker | 60-100 bpm |
| Atrial conduction fibers | 60-80 bpm |
| AV junction | 40-60 |
| Ventricular Purkinje | 20-40 |
| True normal pacemaker | SA node |
| What makes the latent pacemakers emerge? | High parasympathetic tone High catecholamine concentration hypoxemia ischemia electrolyte distrbances drug toxicities |
| Abnormal automaticity | tissue that is not normally automatic becomes automatic; often cannot be overdrive suppressed |
| Triggered activity | early afterdepolarizations delayed afterdepolarizations |
| EAD | occur before full phase 3 repolarization |
| DAD | occur after phase 3 repolarizations |
| Digoxin | Blocks Na/K pump. Dig toxicity will lead to DADs and has increase in intracellular Na+ which will inhibit Na/Ca pump leading to increased Ca in the SR. |
| 1st degree block | every pulse conducts |
| 2nd degree block | some, not all pulses conduct |
| 3rd degree block | no pulses conduct |
| 2nd degree type I | Wenkebach; progressive prolongation thru the av node with an eventual dropped beat |
| 2nd degree type II | Mobitz II; dropped beats without the prolongation of the PR interval |
| 2:1 Morbitz block | dropping every other beat. Every other P wave has a QRS |
| 3:1 Morbitz | 3 P's for every QRS |
| What are some of the mechanisms that could contribute to block in the AV node? | block Ca+ channel Increase vagal outflow Digitalis Hyperkalemia Adenosine |
| Re-entry | circus movement; an impulse that does not die out, it instead continues to circulate and re-excite tissue |
| Conditions that are necessary for re-entry to occur. | 1. unidirectional block, or transient block 2. slowed conduction over an alternate pathway 3. Proximal re-excitation |
| Re-entry may be promoted by ______________ | things that slow conduction velocity, shorten the refractory period or a combination of both |
| Examples of random re-entry | Ventricular Fibrillation |
| Is re-entry ordered or random? | both |
| Re-entry may accur around _______ or it may be ______________. | anatomical;functional |
| Classic example of re-entry | wolff-parkinson-white syndrome |
| WPW | pre-excitation; has an accessory pathway; result is supraventricular tachycardia |
| Pre-excitation shows what kind of wave? | Delta wave |
| 3 Examples of re-entry | V-Fib A-Fib WPW |
Created by:
tjamrose
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