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