Acyanotic CHD

Question 1

L→R shunt: ASD

Answer 1

Presents in childhood - adulthood (later)
10% of CHD
Transmission of flow only
Usually isolated, related to pulmonary valve stenosis, VSD

Failure in septation (growth between endocardial cushions) ~ 30 days (downward growth of septum primum)

• Secundum (50-70%): hole in foramen ovale- PFO
• Primum (30%)- 15% related to AVSD/ECD, at region of endocardial cushions
• Sinus venosus defect (10%): at entry SVC to RA, rarely IVC
• Coronary sinus (rare): at roof of coronary sinus

May get MVP if secundum or sinus venosus
Shunt magnitude/direction depends on size of defect and compliance of RV (higher compliance in RV = L→R shunt)
Leads to R) volume overload and enlargement, increased PBF
Absence of LA enlargement (as blood shunted across ASD)- differentiates between VSD if increased PBF

Natural history

1. Spontaneous closure- if small/young (<3mm, <3mo) 100%, if medium (3-8mm by 1.5yrs) >80%, rare if >8mm to close >4y
2. Usually asymptomatic if large shunt- CCF/pulmonary HTN in 30s/40s
3. Rare complications = arrythmias 13%, paradoxical embolisation

Features:
Asymptomatic
Exercise intolerance

Heart sounds: Widely split/fixed S2
Murmur: Grade 2-3 ejection systolic murmur LUSB (due to increased volume flowing across pulmonary valve), mid-diastolic rumble LLSB (if large, increased volume flow over tricuspid)

RH enlargement

• ECG: R) axis deviation (AVF, II & III positive, I negative), complete/incomplete RBBB, +/- RVH
• CXR: RA/RV enlargement (cardiomegaly), increased pulmonary vasculature if large with increased PBF

Management:

1. Conservative, if CCF- diuretics pre-closure
2. Non-surgical closure (preferred)
   - If <5mm, haemodynamically significant shunt with RV overload, sufficient rim tissue
   - Post infancy (allow time for spontaneous)
   - Minimal complications
3. Surgical closure
   - If CCF not responding to Mx, Qp:Qs 15:1 or greater (significant increased PBF)
   - Delay until 2-4yrs
   - 0.5% mortality
   - Complications = CVA/arrythmias (7-20%, sick sinus syndrome)

Question 2

L->R shunt: VSD

Answer 2

Presents during infancy
Most common defect- 30% of CHD, 15-25% of acyanotic CHD
Transmission of flow and pressure

Associations: Di George, T21, Turners

Failure in any of 3 processes forming ventricle ~Day 25:

1. Protrusion of R) endocardial cushion/L) bulbar ridges (membranous) into AV canal
2. Growth of connective tissue into muscular septum
3. Downward growth of ridges dividing conus

Types:
Membranous: below aortic valve(small) - majority (perimembranous most common)
Muscular
- Inlet septum- 5-7% (beneath tricuspid/mitral valves)
- Trabecular septum (mid, anterior, posterior, apical) - 5-20%
- Outlet/infundibular 5-8% (near aortic/pulmonary valves- can prolapse through VSD)

Vary in size
Generally decrease with age
Perimembranous can involve bundle of his → conduction deficit
Inlet/outlet do not close spontaneously
Spontaneous closure with small (perimembranous/muscular) defects within first 6mo
- 60% mnuscular close (not fter 8yrs)
- 35% small perimembranous close (not after 5yrs)

L→R shunt: increased blood in R side of the heart, increased PBF → congestion, increased PA pressure, increased L) venous return (LAH- not seen in ASD), minimal RV strain

Factors affecting shunting
- Size of defect (small → large resistance, does not depend on PVR, small → less resistence, depends on PVR)
- Pulmonary vascular resistance (lower = increasing magnitude)
→ if large VSD in newborn, minimal PVR → symptoms by 6-8weeks after foetal circulation reverses

Complications:

• RV dilatation/hypertrophy
• Pulmonary vascular obstructive disease (Eisenmengers) increased pulmonary pressures, leads to increased PVR → reversal of shunt (reduces LV overload, LVH disappears on ECG, cyanosis/decreased activity, disappearance of murmur) 6-12mo if large

Examination/features
Small = asymptomatic, moderate-large = delayed growth, exercise tolerance, CCF symptoms, cyanosis if Eisenmonger’s present
Heart sounds: loud P2 if large (elevated pulmonary pressure), loud/single S2 with Eisenmongers (PHTN)
Murmur
- Holosystolic LLSB (flow through defect- louder in smaller VSDs) LUSB = supracristal/outlet
- Apical mid-diastolic rumble (MVS due to increased flow if large VSD)
- Early diastolic decrescendo murmur (AR- if outlet VSD due to valve prolapse)

CCF signs+/- praecordial bulge
Failure to thrive

ECG: LVD/LAH with moderate/large, may have RVH if pulmonary HTN/Eisenmongers
CXR: chamber enlargement with moderate VSD (LA,LV,PV, increased pulmonary markings) large VSD cardiomegaly, biventricular enlargement, Eisenmongers- normal heart size, enlarged PAs

Management:

1. Conservative- treat CCF: diuretics, ACE-i to reduce SVR, no exercise restriction if no signs PHTN
2. Surgical closure: >6-12mo, CCF not responding to Rx, Qp:Qs >2:1, PA pressure >50% systemic, outflow VSD, larger VSDs, contraindicated if shunt reversal
   - direct closure
   - <1% mortality
   - RBBB, L) anterior hemiblock, residual shunt, TR/AR

Question 3

L->R shunt: AVSD/endocardial cushion defect (ECD)

Answer 3

2% of CHD
Most common in T21 patients (70% of patients with ECD)
Combined features of ASD & VSD

Pressure & flow overload
L→R shunt

Complete or partial - endocardial cushion contributed to closure of lower atrium (ostium primum) & upper ventricle, formation of MV/TV

• Complete- involving atrium, ventricle & valves
• Partial- involving atrium & mitral valve
• May also have AV insufficiency

1. Partial (primum ASD):
L→R shunt, RA/RV volume overload, increased PBF
Does NOT spontaneously close
CCF- may develop earlier than seccundum, arrythmias 20%, pulm HTN in adulthood

Features:
Asymptomatic in childhood, dyspnoea, easy fatigue, recurrent LRTI, poor growth → more if associated wit MR
- Hyperdynmic flow, wide/fixed splitting of S2,
- Ejection systolic murmur (PS), mid diastolic murmur (TS), apical holosystolic murmur (MR)

Investigations:
ECG: Superior axis, RBBB- abnormality in bundle of his, 1st degree HB (prolonged PR- 50% of patients)
CXR: enlarge RA/RV, increased PVM, ‘gooseneck deformity’ (L ventriculogram)

Management

1. Treat CCF symptoms
2. Surgical closure- if CCF, failure to thrive, MR <12mo, otherwise elective 2-4yrs if asymptomatic
   - Mortality 3%, 15% revision
   - Arryhtmias common

2. Complete (ASD + VSD, valvular structural changes)
L→ R shunt
Volume overload in all chambers
Magnitude of shunt determined by size of defect regardless of PVR

Question 4

L->R shunt: PDA

Answer 4

Presents: Infancy
5-10% of CHD
Associated maternal rubella, prematurity

Pathophys/haemodynamics:
PDA allows blood flow PA→Ao, bypasses lungs in utero
Low PaO2/PGE keep patent, closes as PaO2 rises after birth
Expect closure within 4-6weeks after birth
Usually due to structural abnormality in ductal smooth muscle

Similar to VSD- flow determined by resistance (diameter/length) of PDA, PVR if large shunt
Aorta will be enlarged prior to PDA

Transmission of flow & pressure

Features:
Asymptomatic if small
If large CCF features, failure to thrive- first few weeks of life
+/- exertional dyspnoea in older children
Recurrent infections
Atelectasis

Bounding peripheral pulses + wide pulse pressures
Hyperactive praecordium
Grade 1-6 ‘machinery’ continuous murmur LUSB (pressure difference PA/Ao in both systole & diastole)
Loud P2
Can develop Eisenmengers → peripheral cyanosis in LOWER body

Investigations:
ECG: normal, LVH → BVH if large, may have RVH if obstructive pulmonary disease
CXR: LA/LV enlargement, PA enlargement- prominant hilar markings if pulmonary obstruction

Spontaneous closure rare unless premature infants
May develop recurrent pneumonia
Rarely aneurysm/burst of PDA
Risk of endocarditis

Management

1. Conservative: minimal effective treatments
2. Non-surgical closure: coil embolisation, closure device
   - Haemodynamically significant PDA with CCF or FTT, increased PBF
   - Contraindicated in Eisenmongers/pulmonary obstructive disease
3. Surgical closure: L) thoracotomy, if non-surgical inappropriate
   - Low mortality and complication rates- mainly RLN palsy

DDx
AV coronary fistula, AV systemic fistula, pulmonary fistula
VSD, AVSD
Absent pulmonary valve
TAPVR

Question 5

Obstructive: Pulmonary stenosis/peripheral pulmonary stenosis

Answer 5

10% of all CHD
3% peripheral pulmonary stenosis
Failure of development (early gestation) of pulmonary valve or insufficient reabsorption of infundibulum
Peripheral occurs in pulmonary artery branches (usually near bifurcation) - often associated with other CHD

Associations
Tricuspid atresia, TOF, TGA, DORV
Rubella- central & peripheral
Allagile- peripheral
Williams- peripheral
Noonan- valvular pulmonary stenosis with dysplastic valves

Types

1. Valvular: valve thickened, fused/absent commissures, small orifice, hypoplastic RV if severe
2. Subvalvular: in TOF, large VSD associated
3. Supravalvular: PA stenosis- may involve single PA or multiple branches
4. Within RV cavity

Mild: RV systolic <50% of LV (45-30mmHg pressure difference)
Moderate: RV <75% of LV (40-70mmHg pressure difference)
Severe RV >75% LV (>70mmHg)

Features
Asymptomatic if mild
Presents in later childhood (moderate)
- Exertional dyspnoea with easy fatiguibility
- CCF/exertional chest pain
Newborns (severe) poor feeding, tachypnoea, cyanosis
Severity progresses with age if mod-severe
Risk of sudden death in severe
If VSD/ASD present, degree of stenosis determines direction of shunt (R→L if severe, L→R if mild stenosis- like isolated ASD/VSD )

Ejection systolic murmur in LUSB radiating to back
Louder = more severe
Peripheral = midsystolic murmur in pulmonary valve region radiating to back
A2 & P2 split widely, decreased P2 intensity with increasing severity
Prominant a wave in JVP
HSM/CCF features
RV hypertrophy

Peripheral = ABSENCE of other findings of valvular pulmonic stenosis – RV lift, soft P2, systolic ejection click

Investigations
ECG: RAD, RVH, RV strain in severe PS (TWI in praecordium)
CXR: prominent pulmonary knuckle due to PA dilatation, cardiomegaly if CCF, decreased pulm vascular markings

Treatment
Exercise restriction if severe
Emergency treatment if critical in newborn
- PGE infusion
- Balloon valvuloplasty
- Ductal stenting/pulmonary shunt if not successful
Surgical:
1. Balloon valvuloplasty
- if pressure gradient >40mmHG
- CCF/exertional chest pain
- dysplastic pulmonary valve (i.e Noonan syndrome)
- Risks- regurgitation
2. Valve replacement
- failed balloon valvuloplasty
- complex lesions
- higher mortality <10% in critically unwell infant