Arrhythmias

1. Arrhythmias Nightfloat Curriculum 2010-2011 LPCH Pediatric Residency Program By Jennifer Everhart, MD

2. Learning Objectives • Recognize common pediatric cardiac arrhythmias • Recognize early signs of clinical decompensation/hemodynamic instability • Initiate management of arrhythmias in the inpatient setting, including identifying and treating reversible causes • Review PALS algorithms for bradycardia & tachycardia

3. Bradyarrhythmias - Symptoms • General: altered LOC, fatigue, lightheadedness, dizziness, syncope • Hemodynamic instability: hypotension, poor end-organ perfusion, respiratory distress/failure, sudden collapse

4. Bradyarrhythmias - Causes • 1º: Abnormal pacemaker/conduction system (congenital or postsurgical injury), cardiomyopathy, myocarditis • 2º: Reversible Hs & Ts: • Hypoxia – Hypotension – H+ ions (acidosis) • Heart block – Hypothermia – Hyperkalemia • Trauma (head) • Toxins/drugs (cholinesterase inhibitors, Ca++ channel blockers, β-adrenergic blockers, digoxin, central α2-adrenergic agonists, opioids)

5. Bradyarrhythmias - Types • Sinus bradycardia • Physiologic (ie: sleep, athletes) vs. pathologic (ie: abnormal lytes, infection, drugs, hypoglycemia, hypothyroidism, ↑ICP) • Sinus node block • Subsidiary pacemakers lead to atrial, junctional, & idioventricular escape rhythms ↓Junctional beat

6. Bradyarrhythmias – AV Blocks

7. 1st degree heart block 2nd degree heart block, Mobitz I 2nd degree heart block, Mobitz II 3rd degree heart block

8. Bradyarrhythmias - Management • Stable patients: • 12 lead EKG, +/- labs, consult cardiology • Unstable patients: • ABCs • PALS Pediatric Bradycardia Algorithm • Address reversible causes (Hs & Ts)

10. Tachyarrhythmias - Symptoms • General: palpitations, lightheadedness, syncope, fatigue, SOB, chest pain • Infants: poor feeding, tachypnea, irritability, sleepiness, pallor, vomiting • Hemodynamic instability: respiratory distress/failure, hypotension, poor end-organ perfusion, altered LOC, sudden collapse

11. Tachyarrhythmias - Causes • 1º: Underlying conduction abnormalities • 2º: Reversible Hs & Ts • Hypovolemia–Toxins • Hypoxia–Tamponade(cardiac) • H+ ions (acidosis)–Tension pneumothorax • Hypoglycemia –Thrombosis (coronary, pulmonary) • Hypothermia–Trauma • Hypo/Hyperkalemia

12. Tachyarrhythmias - Classification • Narrow complex: sinus tachycardia, supraventricular tachycardia, atrial flutter • Wide complex: ventricular tachycardia, supraventricular tachycardia with aberrant intraventricular conduction

13. Tachyarrhythmias - Types • Sinus tachycardia • Usually <220 bpm in infants, <180 bpm in children • P waves present and normal (upgoing in I, II, AVF), narrow QRS, beat to beat variability • Response to body’s need for increased cardiac output or oxygen delivery (ie: hypoxia, hypovolemia, fever, pain, anemia)

14. Tachyarrhythmias - Types • Supraventricular tachycardia • >220 bpm in infants, >180 bpm in children • Abrupt onset; occurs intermittently • Usually narrow QRS, absent or abnormal P waves, no beat to beat variability • Caused by accessory pathway reentry (ie: WPW), AV nodal reentry, ectopic atrial focus

15. Tachyarrhythmias - Types • Atrial flutter • Sawtooth pattern on EKG • Atrial rate 350-400/min; ventricular rate varies • Ventricular tachycardia • Wide QRS (>0.08 sec), P waves may be unidentifiable or not related to QRS • Caused by underlying heart disease, post-heart surgery, myocarditis, cardiomyopathy, ↑QTc, ↑K+, ↓Ca++, ↓Mg++, drug toxicity

16. Tachyarrhythmias - Types • Torsades de Pointes • Variable polarity & amplitude of QRS, appearing to rotate around the EKG isoelectric line • A type of polymorphic VT • Caused by long QT syndromes, ↓Mg++, drug toxicities (including antiarrhythmics) • Can deteriorate to ventricular fibrillation

17. Tachyarrhythmia vs. Artifact • Differentiating arrhythmia from artifact: • Sharp spikes from QRS complexes superimposed on “arrhythmia” • Wandering baseline • Normal QRS complexes in some leads • Causes of artifact: • Simultaneous use of other equipment, muscle contractions, movement

18. Tachyarrhythmias - Management • ABCs • If pulse → PALS tachycardia algorithms • Poor perfusion → Pediatric Tachycardia With Pulses and Poor Perfusion algorithm • Adequate perfusion → Pediatric Tachycardia With Adequate Perfusion algorithm • If no pulse → PALS Pediatric Pulseless Arrest algorithm

19. Tachyarrhythmias - Management • In general… • Attach monitor/defibrillator, pulse ox; establish vascular access • Obtain appropriate labs (ie: blood gas, lytes) • Identify & treat any reversible causes • Torsades de Pointe or VT due to ↓Mg++ • Magnesium sulfate

20. Tachyarrhythmias – Management • SVT with adequate perfusion • Vagal maneuvers while preparing adenosine • SVT with poor perfusion • Immediate adenosine or cardioversion • Consider vagal maneuvers if no delay • Adenosine • Rapid bolus then flush using proximal PIV or CVL • 0.1 mg/kg; max 1st dose 6 mg; additional 0.2 mg/kg if needed (max 2nd dose 12 mg) • Cardioversion (0.5-1 J/kg; sedate if possible)

24. Case #1 • 9 year old boy admitted for asthma exacerbation, noted to have heart rate of 55.

25. Case #2 • 3 month old girl brought to ED for poor feeding and fussiness, noted to have heart rate of 230.

26. References • American Heart Association. 2005 American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation (CPR) and Emergency Cardiovascular Care (ECC) of Pediatric and Neonatal Patients: Pediatric Advanced Life Support. Pediatrics 2006;117;e1005-1028. • Fleisher GR, et al. Textbook of Pediatric Emergency Medicine 5th Edition. Lippincott Williams & Williams, 2006. • Pediatric Advanced Life Support. American Heart Association, 2006. • Thaler MS. The Only EKG Book You’ll Ever Need4th Edition. Lippincott Williams & Williams, 2003. • Zaoutis LB and Chiang VW. Comprehensive Pediatric Hospital Medicine. Mosby Elsevier, 2007.