Cardiology Flashcards
What are the shunts in neonatal physiology?
ductus arteriosus ( from pulmonary trunk to descending aorta) ductus venosus (umbilical vein into IVC) foramen ovale (R to L atrium) (placenta)
Changes to physiology after birth
Baby breathes reducing pulmonary vascular resistance** – PVR @ birth is similar to SVR, but PVR steadily drops over 4-8wksweeks, can occur more quickly if O2 given increased systemic vascular resistance** (because placental circulation no longer part of circuit) closure of 3 shunts -PFO (passively closes) - ductus venosus (passive - shortlists after birth, complete closure in 3-7 days) - ductus arteriosus*** —functionally closes <24hrs due to oxygenation and prostaglandins — passively closes/fibroses in 2-3 weeks ** Drs can manipulate this
How common is congenital heart disease?
6-8 per 1000 live births most common congenital defect
What syndromes are associated with CHD?
Down syndrome (trisomy 21)
- 50% risk of CHD
- AVSD (atrioventricular septal defect)
- VSD
Velocardial facial syndrome (VCFS)
- VSD, tetralogy, truncus arteriosus
William Syndrome (7 del) - supra aortic stenosis Turner syndrome - coarctation, bicuspid
CHARGE syndrome
Trisomy 13, 18
Noonan syndrome
Symptoms + signs of CHD?
HISTORY
Cyanosis
Congestive cardiac failure
- tachypnoea +/- increased WOB
- poor feeding/failure to thrive/reduced ET** very important signs
- tachycardia
EXAMINATION
(does the patient look dysmorphic?)
tachycardia/hypoxia/tachypnoea/BP
cyanosis (need SpO2 85% to be visible)
clubbing (late sign, ~12 -18 monts)
pulses (upper + lower body)
hepatomegaly (late)
pericardial overactivity/thrill (late)
murmur
VSD
One of the most common types of CHD
CLASSIFICATION (restrictiveness, location - different behaviour, Mx + prognosis)
Non-restrictive (hole big enough that blood can get through hole)
– potentially worse prognosis if untreated, as increased SVR from higher LV pressures causes damage to pulmonary bed (Eisenmenger syndrome)
- therefore need to close in 1st year of life
- often no murmur
Restrictive ( blood can’t get through) - audible murmur
Muscular VSD (20%)
- likely to close spontaneously
Perimembranous (80%)
- aneurysm formation aortic regurg
Outlet/infundibular/juxta-arterial (8%, 30% in Asians)
- unlikely to close - likely to affect valve esp aortic valve
FEATURES
- MURMUR + CHF (congestion, failure to thrive)*
- PVR raised as neonate, so VSD may not be heard (as not much of a gradient btw PVR/SVR left/right)
- THEREFORE —> more likely to pick up murmur @ 6-8 week mark when PVR reduces
– Bub more likely to be symptomatic as R → L shunt WORSENS (O2 also worsens this as further reduces PVR)
Coactation of aorta
juxta-ductal (abnormal extension of PDA, so it closes + causes CoA) pre-ductal post-ductal PRESENTATION = highly variable - poor feeding - poor weight gain - metabolic collapse - decreased femoral pulses** VERY IMPORTANT SIGN TREATMENT - use prostin, to re-open ductal tissue (temporising) - surgery
Give overview of Tetralogy of Fallot features, findings, Mx
CYANOTIC condition
4 features of ToF
- unrestrictive VSD
- pulmonary stenosis/RVOT
- ( = deoxygenated blood shunts to systemic circulation)
- overriding aorta
- results in RV enlargement -> Eisenmenger
PRESENTATION = variable!
Cyanosis (MOST) w too little pulmonary flow (too much R → L shunt)
Tachypnoea + pulmonary oedema
- but can also have too much pulmonary blood flow if pul stenosis less of a thing, ∴ so manifests as congestive heart failure
Murmur - ejection systolic murmur
“Tet” spells - where baby gets upset, vicious cycle of increasing cyanosis, can be life-threatening*
CXR - R) sided aortic arch, lung field oligaemia (lack of pulmonary blood flow)
Aortic stenosis
Non-cyanotic too little systemic blood flow - presentation depends on severity of stenosis Mx - if unwell, prostin to keep duct open - catheterisation with balloon valvuloplasty - surgery
TGA - transposition of great arteries
CYANOTIC condition pulmonary and aortic arteries switched around with two seperate circulations - condition only survivable if there is mixing btw circulations eg: VSD, PDA, ASD PRESENTATION - cyanosis at birth - metabolic collapse - hyperoxy test = give lots of O2 and see if it makes a difference eg: if CHD, won’t improve, if lung disease then will improve -septostomy - early surgical repair is vital
Recognition and diagnosis
- when do we look for CHD? What can be missed?
Antenatal
only ~30% of lesions are picked up antenatally
Newborn check
PVR still raised, ductus may still be open
= MANY LESIONS WILL BE MISSED
6 week check
PVR should have dropped
Ductus should have closed
= VERY IMPORTANT TIME TO RE-CHECK
PVR decreases (eg: VSD)
- murmurs may change or appear
- there is increased pulmonary flow
Duct closes
- duct dependent PVR ( too little pulmonary flow)
- eg: pulmonary stenosis
- duct dependent SVR ( too little systemic blood flow)
- eg: aortic stenosis
When to be concerned re: CHD in baby + investigations would you order?
murmur characteristics
- Loud murmur
- diastolic murmur (difficult due for fast HR)
- continous murmur
Other signs
- tachypnoea
- hepatomegaly
- decreased pulses
- cyanosis
- abnormal Ix
-
ECG (needs to be paediatric specific)
- include V3r/V4r
- R) side forces prominant
-
bloods
- ABG - hypoxia, low Ca in VCFS
- genetic tests for T21, VCFS
-
CXR (size, position, contour, pul vascularity)
- increased pulmonary vasculature(flow)
- increased heart size
- abnormal cardiac contour
- eg: boot shaped heart where apex of heart lifted up off diaphragm, sign of RV hypertrophy, pul stenosis, ToF)
- eg: dropped egg, thin mediastinum, increased pul blood flow
- eg: cardiomegaly + increased pul markings in unrestrictive VSD
- Echo
- not a routine service, should be in conjunction w paediatric cardiologist
-
ECG (needs to be paediatric specific)
MRI/CT, nuc med, cardiac catheterisation (Dx, HD, interventional)
normal ECG features of neonate
- neonate has RV dominance (QRS progresion in chest leads)
- relative tachycardia
- QRS duration shorter (<70ms)
- QTc long compared w children and adults
all of the above
Principles of management of CHD
NB: is there a problem that needs management?! Surveillance
General Mx
- endocarditis prophylaxis
- good dental hygeine
- ensuring growth/nutrition maintained
- immunisation (normal schedule)
- general infections
- if pt in heart failure, more prone to persistent repsiratory symptoms
- lower threshold for Abx/Rx
- dehydration eg: gasto Rx seriously as can lead to thrombosis
- exercise
- CVS risk factor Mx
- eg: BP/lipid risk
- TRANSITION TO ADULTHOOD
- psychological support to patient and parents
Too much pulmonary flow
= L to R shunts eg: unrestrictive VSD
w symptoms of pulmonary oedema
Mx
diuretics
avoid supplemental O2
optimise for surgery (big enough, well enough)
prevent irreversible damage to pulmonary vasculature (Eisenmenger syndrome) by pulmonary artery band
complete surgery eg: VSD patch repair
Too little pulmonary blood flow
eg:
Mx
medical - prostaglandin E1 (to keep PDA open)
Catheter valvuloplasty (temporising)
surgery
- arterial shunt (palliative, shunt from subclavian artery to pulmonary artery)
- complete repair
Types of arrhythmias in neonates + Mx
SVT (AVRT)
rate almost 300 bpm
normal electrical conduction, but also has accessory pathway which creates a short circuit loop
Rx
- vagal manouvres (dunk into ice cold water, gag reflex
- adenosine
- longerterm anti-arrhythmics (sotolol, beta blockers, flecanide
Px - 60 -70% resolve by 12 months, if no further episodes can cease meds
30- 40% require EPS + ablation (~5 yrs old)
atrial flutter
complete heart block
long QT syndrome
abnormal K+ or Na+ channels
- delayed ventricular repolarisation + prolonged QT -> risk of VT + VF
autosomal dominant, 1:2500 people in Aus, up to 10% of SIDS
Ix - if maternal or paternal Hx of LQT -> ECG (neonatal ECG can be physiologically prolonged, recheck in 6 weeks)
Mx - if high suspicion -> beta blockers
How to differentiate normal ‘innocent murmur’ from abnormal
is the murmur associated with one or more of:
- failure to thrive
- cyanosis
- S+S of heart failure
- dysmorphism
- abnormal pulses
- clubbing
- hepatomegaly/ pericardial thrill
Murmurs are not always abnormal
innocent murmur
- every child will get a murmur from time to time (and no physical manifestations of heart disease eg: CHF, cyanosis)
Tend to be:
- ejection systolic
- vibratory/musical
- often loud, but not associated w precordial thrills
- change w body position (eg: sitting > standing often softer)
- vary considerably with review, augmented by illness
What are the common heart disease lesions?
CONGENTIAL
VSD - most common (35 - 45%)
Persistent (PDA)
ASD
PV stenosis/ AS / coarctation of aorta (5%)
CYANOTIC
PV stenosis
ToF/TGA (1%)
ACQUIRED
rheumatic heart disease
kawasaki disease (coronaries)
Arrhythmias, cardiomyopathies
Complications of cyanotic heart disease (ie: R -> L shunts)
- hypoxia
- myocardial/endo organ dysfunction
- paradoxical embolus (no lung filtering system)
- polycythaemia
- neurological sequelae (stroke/plegia/abscess)
- reduced ET
- bleeding
Endocarditis prophylaxis recommendations
recommended in:
- cyanotic patients
- prosthesis (valve, conduit etc)
- selected high risk post-op patients
- within 6 months of cardiac surgery (to allow for prosthetic material to be endothelialised)
- rheumatic heart disease
Choice of Abx
- selected according to procedure (often amoxicillin/ampicillin -> if allergic = clindamycin)
- one dose immediately pre, and some situations 2nd dose at 6hrs
pt still at risk of endocarditis!!
**- good dental hygeine is KEY
(CSANZ website for Abx choice in endocarditiis prophylaxis)**
