Conduction Disorders


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Apr 25 2018 24 mins   11
This week on PA Study Sesh we are starting the cardio chapter and discussing conduction disorders.
Sinus Arrhythmia

* Appears as normal sinus rhythm, but rhythm is irregular
* Normal variant
* INcreases during INspiration

Sinus Bradycardia

* <60BPM
* #1cause=vagal stimulation=increased acetylcholine (increased parasympathetic activity)
* Tx: Atropine (anticholinergic)

Sinus Tachycardia

* >100BPM
* Tx: Vagal maneuvers, adenosine, bblockers, CCB, Digoxin (ABCDs)

Sick-Sinus Syndrome

* Combo of sinus arrest with paroxysms of tachy & brady arrhythmias

* TX: permament pacemaker if symptomatic

* If V-tach=with automatic implanatable cardioverter-defibrillator

Premature Atrial Contraction (PAC)

* Abnormal P wave followed by QRS

* May be unifocal or multifocal

* Non-compensatory pause

* Next normal p wave is not where expected

* Usually benign, though may increase risk of arrhythmias if combined with other heart abnormalities.

Atrial flutter

* “saw tooth” waves
* Tx:

* Stable: vagal maneuvers, b-blockers, ccbs
* Unstable: synchronized cardioversion
* Definitive= ablation

Atrial fibrillation

* #1 chronic arrhythmia
* Irregularly irregular with narrow QRS

* No distinct P waves

* Loads of causes

* Often associated with hyperthyroid
* Also atrial enlargement

* Increased risk of clots (blood isn’t moving properly out of atria)
* Tx:

* Stable: rate control

* B blockers #1: metoprolol
* CCBs: Diltiazem or Verapamil (nondihydropyridines)
* Digoxin if hypotensive or CHF

* Unstable:

* Synchronized cardioversion

* Management:
* Anticoagulation

* Factor Xa inhibitors

* “Xabans”
* Bind to antithrombin III

* Dabigatran

* Direct thrombin inhibitor

* Warfarin

* If other drugs contraindicated

* Dual anti-platelet therapy

* Aspirin + Clopidogrel
* Less effective than anticoagulant monotherapy

Paroxysmal Supraventricular Tachycardia (PSVT)

* 2 types

* AV nodal reentry #1

* 2 paths within AV node (one slow & one fast)

* Av reciprocating

* Accessory pathway outside the av node

* Wolff-Parkinson White
* Lown-Ganong-Levine Syndrome

* Wide or narrow QRS complex

* Depends on which pathway is taken first

* Wolf-Parkinson White

* Accessory pathway=bundle of Kent

* Ventricles are “pre-excited”

* Can develop tachyarrhyhmias

* EKG:

* Delta wave

* Slurred QRS

* Candle

* Wide QRS
* Short PR Interval

* Management:

* Avoid av nodal blockers because current may preferentially travel down accessory pathway

* Lown-Ganong-Levine Syndrome

* Short PR interval with normal QRS

* Bundle of James

* Management (of all PSVT)

* Narrow complex

* Vagal maneuvers

* =increased acetylcholine=decreased heartrate

* Adenosine#1
* B or CCBs

* Wide Complex

* Amiodarone