Sinus Nodal Arrhythmias General Sinus Nodal Arrythmia with Normal Conduction Sinus Tachycardia/IST Sinus Arrhythmia Sinus Bradycardia Sinus Nodal Arrythmia with Abnormal Conduction Sinus Node Re-Entrant Tachycardia Sick Sinus Syndrome (SSS) Heart Blocks Sinus Blocks AV Blocks Bundle Branch Blocks Hemiblocks Sinus Nodal Arrythmia with Normal Conduction General Includes Sinus Tachycardia and Inappropriate Sinus Tachycardia Can be Pathologic or Physiologic: SA node dysfunction and AV conduction block MCCs Failure of initiation or conduction Rate of generation of impulses is reduced to <60bpm Common in Athletes, low tone in sleep, increased vagal tone May be due to hypoventilation (hypoxia) BB and CCBS are a common cause Need permanent pacemaker Diagnosis: 12-Lead EKG Treatment Asymptomatic: Leave them alone Symptomatic (hypotension, shock, AMS, ischemia, HF) IV Atropine If Inadequate response IV epinephrine/dopamine or transcutaneous pacing Dual Chamber Pacemaker eventually Irregular Arrythmia (Normal Rate, Irregular Rhythm) In response to vagal tone that causes an alteration in the respiratory cycle Changes seen in R-R interval commonly seen in children R-R Increases during inspiration, decreases during expiration Sinus Nodal Arrythmia with Abnormal Conduction Bundle Branch Block Sick Sinus Syndrome (SSS) Intrinsic SA node disease, can progress into the SA node itself and into the perinodal area Impaired SA node automaticity because of fibrosis and/or degeneration of the SA node and surrounding myocardium Unresponsive supraventricular (AV and junctional) automaticity foci (no escape mechanism) Excessive parasympathetic activity depresses the pacing of the SA node and depresses the supraventricular foci Symptoms Confusion, dizziness, fatigue, Lightheaded, palpitations, presyncope, syncope Bradycardia MC finding on EKG Associated with Adam-Stokes attacks Can result in bradycardia-tachycardia syndrome (alternating brady and Paroxysmal SVT (often Afib)) Sinus pauses/arrests, SA exit block, or alternating bradycardia and atrial tachyarrhythmias Tachycardia-Bradycardia Syndrome EKG: Sinus Bradycardia with delayed/dropped P waves MC Types: 1) Symptomatic Sinus Bradycardia 2) Sinus pause (cessation of SA node impulse generation) and sinus arrest 3) Sinus Node Exit Block (impulse generated normally in sinus node, but fails to conduct within the SA node or perinodal tissue) 4) Tachycardia-Bradycardia Syndrome: Alternating tachy/bradycardia TAs: Afib, Atrial Flutter, Atrial Tachycardia Rapid rhythm suppresses the SA node, the SA node tries to take over after but since there is SSS, there is a long pause after rhythm termination A slow junctional rhythm or sinus bradycardia may take over after the pause Management Assess for meds: Acetylcholinesterase Inhibitors (Donepezil, rivastigmine, and galantamine) Associated with bradycardia, heart block, and syncope Substitute with memantine 24 hour monitoring if arrhythmia is intermittent Echo indicated if syncope or near syncope Treatment Type 1 or 3: Dual Chamber Pacemaker Type 2: Symptoms + Sinus pauses >3s: Dual Chamber Pacemaker Type 4: Dual Chamber Pacemaker ± Antiarrhythmic Heart Blocks Sinus Block Aka Sinus Nodal Block No P waves Doesn’t change subsequent timing, but may see escape beat SSS is a type AV blocks Normal: PR is 120-200ms PR >200ms indicate AV block AV conduction system comprises: AV node, the bundle of His and its left and right bundle branches 3 degrees of AV blocks depending on the extent of impaired conduction Causes Lyme, Chagas, Syphilis SLE Mom w/kid Congenital AV block w/ normal heart Acute MI – transient 1 or 2 av block Inferior > anterior acute MI is going to cause a 2nd degree or higher Diagnosis: Determine the level Vagal maneuvers, carotid sinus massage Slow AV conduction, less effect on infra-nodal tissue Exercise, atropine, isoproterenol Improve AV conduction, impair infra-nodal conduction 1) Normal QRS (<120msec) - Likely due to delayed AV node conduction 2) Prolonged QRS (>120msec) - Delay below AV node, may progress to 2nd degree Medications that can cause AV Blocks (ABCD) – SA/AV nodal blockers Adenosine Beta Blockers Beta-1 specific (metoprolol) have greater HR affects Bradycardia, heart block, hypotension, AMS, normal vision CCBs (Diltiazem and Verapamil) Digoxin Used in Atrial Fibrillation in HFrEF Bradycardia, heart block, hypotension, AMS, Altered Vision 1st Degree AV Block Usually, benign prolongation of AV node conduction Fixed, regular rhythm with P-R interval prolonged (>200ms) 1:1 conduction of the AV node is well preserved 1 P wave corresponding to 1 QRS Causes are usually reversible: BBs and CCBs (depress AV node conduction) Vagal maneuvers that increase tone (sleep) Transient ischemia (RCA angioplasty complication) Metabolic (Hyperkalemia) Non-reversible AV node sclero-degenerative diseases, MI, trauma during surgery or ablations Treatment: Usually asymptomatic: No treatment 2nd Degree AV Block Intermittent conduction Mobitz Type I (Wenckebach) Block involving the AV node Usually, benign AV node conduction dysfunction Characterized by a gradual progression of the PR interval with each beat until a QRS does not follow a P wave for a single beat (P wave without a QRS) The PR interval following the non-conducted wave is usually short RR interval is irregular Usually doesn’t involve the bundle of His Causes: Athletes with high vagal tone, OSA (high vagal tone) RCA MI may have, usually reversible Fatigue/Dizziness occasionally Treatment Symptomatic: Pacemaker Asymptomatic: Observe Mobitz Type II (Mobitz) Block of the Purkinje fiber bundles (His or Bundle Branches) Sudden loss of the QRS complex following a p wave without progressive P-R lengthening on prior beats (PR interval is fixed) Most waves conduct 1:1 with similar PR intervals, and the non-P wave suddenly does not conduct to a QRS Sometimes 2 sequential P waves are followed by a QRS in the case of a 2:1 Mobitz Type II AV block, and 3 sequential P waves follow a 3:1 block Irreversible usually: Hyperkalemia, aging due to sclero-degeneration of the AV node, MI, cardiac surgery or ablation mistakes May progress to 3rd Degree heart block, Bundle branch block Treatment Asymptomatic or Symptomatic: Pacemaker 3rd Degree AV Block (Complete Heart Block) Lack of conduction across the AV node (Block between SA and AV node) Complete dissociation between atrial and ventricular contractions Usually, an intrinsic AV node dysfunction May occur due to extensive ischemic myocardial injury (anterior or inferior MI), sclero-degeneration of the AV node, during catheter ablation and cardiac surgery of the valves Trifasicular or bifasciular can progress to complete heart block Syncope, SCD Inferior MI block is usually transient Anterior MI blocks are usually permanent 2nd /3rd degree blocks likely need temp pacer -> permanent Infiltrative diseases of the heart such as sarcoid Congenital block may be asymptomatic until adolescence, still need pacemaker Reversible causes: hyperkalemia (hemodialysis patients or patients on ACEI), BB, CCBs, or digoxin Atrial impulses fail to capture ventricles Escape rhythm is usually present Narrow (Junctional Escape) or Wide (Ventricular Escape) Ventricular asystole (syncope/death) unless an escape rhythm is initiated: P waves do not relate to QRS (AV dissociation) Regular RR and PP intervals, Atrial Rate > Ventricular Rate (<50) P waves appear with a different rate than the ventricular escape rhythm Symptoms Lightheadedness, fatigue, SOB, or presyncope and syncope Adams-Stokes (or Stokes-Adams) attacks are attacks of syncope in the setting of a 3rd Degree AV Block/SVT/Afib Brain blood supply insufficiency may cause LOC Treatment Intermittent w/Bifasicular or Trifasicular block Asymptomatic or Symptomatic: Temporary pacemaker Permanent if no reversible cause found