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ECGs Made Easy Ch. 5
Junctional Rhythms
| Question | Answer |
|---|---|
| The AV Node and non-branching portion of the Bundle of His is called the what? | AV Junction |
| What is the flow of the Cardiac Electrical Circuit? | SA Node (Right and Left Atria Depolarize/Contract) AV Node AV Junction Bundle of His Right and Left Bundle Branches Purkinje Fibers (Right and Left Ventricles Depolarize/Contract) |
| What is the intrinsic timing of the... SA Node? Bundle of His/AV Junction? Purkinje Fibers? | 60-100 40-60 20-40 |
| Why would the AV Node become a pacemaker? (Reasons pacing would begin somewhere other than the SA Node) | SA Node fails to create impulse SA Node has impulse, signal is blocked. (Sinus Block, Sinus Arrest) The rate of SA Node is slower than AV Junction. (Sinus Bradycardia or Sinus Arrhythmia) SA Node has impulse but not conducted to Ventricles |
| When conduction begins in the AV Junction: Change in flow and corresponding EKG changes | Electrical impulse will need to travel backwards to depolarize the atria(Inverted P Wave, II, III, aVF) Electrical impulse has a shorter distance to travel from AV Junction to Ventricles(Short PR Int. <0.12 sec) Impulse travels normally through Bundle B |
| Where is the P Wave when the Atria depolarizes before the Ventricles? | The P Wave is inverted and before the QRS complex. |
| Where is the P Wave when the Atria and Ventricles depolarize simultaneously? | The P Wave is hidden in the QRS Complex. No P Wave visible. |
| Where is the P Wave when the Ventricles depolarize before the Atria? | The P Wave is inverted after the QRS Complex. (Before the T Wave) |
| What is a PJC? | A PJC occurs when an irritable site within the AV Junction fires before the SA Node. |
| What causes a PJC? | Acute Coronary Syndrome, Electrolyte Imbalances, Heart Failure, Mental and Physical Fatigue, Rheumatic Heart Disease, Valvular Heart Disease, Stimulants |
| What is a Compensatory Pause? | Often follows a PVC; A delay in conduction that is the same as 2 normal R-R Intervals. |
| What is a Non-Compensatory Pause? | A delay in which the SA Node resets it's rhythm for the next normal beat; A delay in conduction that is less than 2 normal R-R Intervals. |
| What is a Junctional Escape? | Can occur when a rhythm or premature beat results in delay or pause in conduction, The AV Junction tries to "regulate" the pause, The beat itself looks like a PJC but it occurs after the next expected sinus beat (not premature), Non-Compensatory Pause, |
| What is a Junctional Rhythm? | Several sequential Junctional Escape Beats, Starts above the ventricles (Pacing from AV Junction 40-60 bpm), QRS Complex usually narrow, Rhythm regular |
| What causes Junctional Rhythm? | Many of same causes as PJCs, ACS, particularly inferior wall MI, Medications, Increased parasympathetic tone |
| What is Accelerated Junctional Rhythm? | Looks like Junctional Rhythm only faster - AV Junction conduction speeds up due to automaticity (fires at 61-100 bpm) |
| What causes Accelerated Junctional Rhythm? | Very similar to Junctional Rhythm COPD Digitalis Toxicity Hypokalemia |
| What is Junctional Tachycardia? | Ectopic rhythm that does NOT begin at AV Junc but at Bundle of His Most likely caused by enhanced automaticity Beats can look like Junctional Rhythm Occurs when 3 or more beats occur at rate >100bpm Can be paroxysmal or non-paroxysmal |
| Non-Paroxysmal? | Gradual onset Usually begins at Accelerated Junctional Rhythm and transitions to Junctional Tachycardia |
| Paroxysmal? | Sudden onset Usually precipitated only by a single PJC to Junctional Tachycardia |
| At rates >150 bpm, it can be difficult to tell Junctional Tachycardia apart from what and why? | AVNRT and AVRT due to difficulty discerning P waves |
| Origin of PAC? | Irritable atrial tissue |
| Couplet: | Two premature beats in a row (Paired Beats) |
| Runs or Bursts: | Three or more premature beats in a row |
| Bigeminy: | Every other beat is a premature beat |
| Trigeminy: | Every third beat is a premature beat |
| Quadrigeminy: | Every fourth beat is a premature beat |
| Noncompensatory Pause: | The delay during which the SA node resets its rhythm for the next beat, Often follows a PAC/PJC, Less than 2 normal R-R Intervals |
| Compensatory Pause: | Pause for which the normal beat after a premature complex occurs when expected; also called a complete pause, Often follows a PVC, 2 normal R-R Intervals |
| How to determine if Compensatory or Noncompensatory? | Measure distance between R-R Intervals of 3 normal beats, compare measurement with distance between R-R Interval of 2 beats plus premature complex |
| When is a pause Noncompensatory? | If the period between the complex before and after a premature beat is LESS than 2 normal R-R Intervals |
| When is a pause Compensatory? | If the period between the complex before and after a premature beat is the SAME as 2 normal R-R Intervals |
| Narrow QRS Complex? (QRS Morphology) | Sinus, Atrial or Junctional origin |
| Wide QRS Complex? (QRS Morphology) | Ventricular origin, or supraventricular with aberrant conduction |
| Junctional Escape Rhythm: P wave present? Narrow or Broad complex? | P wave can be inverted or absent, Narrow QRS complex |
Created by:
kdanie24
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