All I need is a cast…

Shawn Dowling, PGY-4

Case

• 11 yoa M. Seen in ED last week after fall during Lacrosse game.– Dx with a Distal Radius Buckle #– Discharged with a removable brace.

• Returns to ED today to get a cast because his “friends” are hitting his broken arm in the splint

Physical Exam

• BP – 116/70, • HR – 42, RR-20,

SpO2-97%• Tender at distal

radius• Wrist/elbow shoulder

normal

Normal Vital Signs

Your options

1. Describe to him the Buckle Fracture study in detail and keep him in the splint

2. Cast him and avoid the hassle

3. 1 or 2 + have a discussion about what “friends” are

4. 3 + ECG

Diagnosis?

P’s map out

QRS’s map out

Where is the escape rhythm coming from?

Complete heart block

• No atrial impulses reach the ventricle through the AV conduction system– AV Dissociation– :. Always more atrial beats than ventricular

• Escape rhythm can occur anywhere below site of block – The more distal, the slower the HR– The higher the block the more likely to respond to

atropine/catecholamines– Proximal to/at bundle of His; narrow QRS, HR>40– Distal to bundle of His; wide QRS, HR<40

Further history

• Patient had presyncope and SOB with exertion in the past

• Saw pediatrician a few years ago– Did iron studies -> normal,

told there is nothing to be concerned about

• Over past few months increasing Sx

• Made appt with FP for two wks from now

• PMHx – ADD • Meds - Concerta, • FHX – no SCD, no

premature deaths, no pacemakers

DDx

• Idiopathic progressive cardiac conduction dz

• Ischemic heart disease• Drugs (many, MC are…)

– Amiodarone– B-blocker– CaCB– Digitalis– Concerta NOT one

• Valvular Heart disease– Calcification extend to AVN

• Hyperkalemia

• Infiltrative dz – lymphomas, tumours

• Familial disease• Congenital Complete

heart block• Infectious/Post-infectious

– Myocarditis– Rheumatic fever– Lyme carditis

Congenital Complete Heart Block

• Incidence – 1 in 15,000 – 22,000

• Diagnosed:– In utero/Neonatal– Later in childhood

• Etiology:NEONATAL– Neonatal Lupus (95%)

LATER IN CHILDHOOD– Myocarditis– AV discordance– Corrected TGA– Polysplenia with AV

defect– Hereditary disorders

Pathophysiology – Neonatal

• With neonatal lupus the problem is maternal lupus AB

• These AB bind to AV nodal tissue leading to autoimmune injury and fibrosis of the AV node and surrounding tissue

Pathophysiology – older children

• With most other causes, the problem is fibrous tissue that either replaces the AV node/surrounding tissue or there is a disconnect between the atrial myocardium and the AV node

In Utero/Neonatal presentation

• Bradycardia is the MC presentation• IN UTERO

– Significant number have IUFD (7-21%)– Other presentations include hydrops fetalis, PCE

• NEONATAL– High neonatal MR (9-27%), – Worse Px when fast atrial rate (>150bpm) and slow

ventricular rate (<50bpm)– Better PX when Dx as neonate (rather than in utero)

Childhood presentation

• Up to 40% may not present until older (mean age 5-6 yoa)

• 5% had unrecognized neonatal lupus• Can be intermittent initially – becomes

persistent with advancing age– Age at presentation likely dependent on VR

• Usu present w/ bradycardia related Sx – Exertional SOB– Presyncope/syncope

Treatment

• In utero/perinatal– Steroids (if associated with neonatal lupus)– Isoproterenol

• Childhood– Pacemaker (type based on MD preference)

• Ventricular (VVI)• Dual Chamber(DDD): MC since more physiologic,

– 90% by age 60

Pacemaker IndicationsClass I conditions• Symptomatic bradycardia (syncope or

presyncope) • Moderate to marked exercise intolerance • Heart failure thought related to the

bradycardia • Left ventricular dysfunction or low cardiac

output • A wide QRS escape rhythm or block below

the His bundle [33] • Complex ventricular arrhythmias [31,37] . • In an infant, <50 to 55 bpm or <70 bpm

w/SHD• Sustained VT• 2 or 3 ºAVB >7 post cardiac Sx• Cardiomegaly• Prolonged QT• Ventricular arrhythmias related to a slow

rate or abolished by a more rapid heart rate.

Class II conditions• 2 or 3 ºAVB within the bundle of His in an

asymptomatic patient. • Prolonged subsidiary pacemaker recovery

time with a pause greater than three seconds

• Transient post Sx 2 or 3 ºAVB that reverts to bifascicular block.

• 2 or 3 ºAVB and a ventricular rate below 50 bpm when awake beyond the first year of life

• Complete AV block with double or triple rest cycle length pauses or minimal heart rate variability.

• Asymptomatic neonate with congenital complete heart block and bradycardia in relation to age [3] .

• Long QT syndrome. • CHD and impaired hemodynamics due to

sinus bradycardia or loss of AV synchrony. • Neuromuscular disease with any degree of

AV block

Prognosis

• Neonatal CHB– 17% die prior to 3 months (usually from fetal

hydrops/premature delivery)

• Childhood CHB– Higher likelihood of poor outcome in patients with HR

<50 and with unstable jxn escape– Study of 102 patients followed up between 7-30 years

• 27 patients had syncopal episode• 8 of these were fatal, 6/8 were first syncopal episodes• 44 of the remaining patients received a pacemaker

– HR decreased with age from 46bpm at age 15 to 39 bpm at 40 yoa

– Everyone with a prolonged QTc had a syncopal attack

• Without PM:– Many develop cardiomegaly (compensatory

for low CO) and CHF– Risk of SCD increases with age

Px Post-Pacemaker

• Px is excellent with pacemaker– 5-11% develop CHF– Related to myocardial fibrosis, ventricular

asynchrony– Will require – Most live normal productive life