CardiologyTier 2Disease (DEADMAN)

Congenital heart disease - atrial and ventricular septal defects

Description

Left-to-right shunt at atrial or ventricular level
ASD -> RV volume overload. VSD -> LV volume overload
- Different level shunted -> different chamber dilates -> different ECG
Qp:Qs quantifies the shunt
Large unrepaired shunt
- inc pulmonary blood flow
- -> pulmonary vascular remodelling, inc PVR
- -> shunt reverses
- -> Eisenmenger syndrome (closure then contraindicated)

Epidemiology

ASD type	Share	Key feature
Secundum	~75%	F>M; percutaneously closable; RAD on ECG
Primum	15-20%	Partial AVSD; Down syndrome; extreme LAD
Sinus venosus	5-10%	Usually SVC type; anomalous pulmonary venous return
Unroofed coronary sinus	<1%	Rare

VSD anatomy: perimembranous ~80%, muscular 15-20%, outlet ~5%, inlet <1%
VSD is the commonest congenital cardiac lesion at birth; most small ones close spontaneously

Aetiopathogenesis

ASD - isolated; primum defects sit on the AVSD spectrum
VSD
- Congenital - isolated, syndromic (Down, Turner), or part of TOF
- Acquired - post-MI VSD, ~day 3-5 after full-thickness infarct
Shunt magnitude depends on defect size and the relative compliance/resistance downstream
- ASD: RV compliance
- VSD: PVR vs SVR

Diagnosis

ASD

Fixed split S2 + pulmonary flow murmur
- The murmur is flow across the pulmonary valve - the defect itself is silent
ECG: RBBB or RSR' in V1; RAD = secundum, extreme LAD = primum
TTE; TOE for sinus venosus defects and anomalous pulmonary venous drainage

VSD

Harsh pansystolic murmur + thrill at LLSE, 3rd-4th ICS
- Loudness is inverse to size - small restrictive VSDs are the loudest
ECG: hypertrophy pattern tracks shunt size; normal if small
TTE gold standard - location, size, direction, gradient, PASP, associated AR

Both

CXR: pulmonary plethora, cardiomegaly
CMR if echo non-diagnostic
Cath for PVR and Qp:Qs by sequential oximetry

Management

ASD - close if

Symptoms, OR RV enlargement, OR Qp:Qs >1.5
Paradoxical embolism, or platypnoea-orthodeoxia
*Contraindicated once Eisenmenger physiology is established*
Percutaneous device for secundum; surgery for primum, sinus venosus, unroofed coronary sinus
Arrhythmia risk after closure is predicted by age at closure - earlier is better

VSD - close if

Symptoms, OR LV volume overload, OR Qp:Qs >2.0
PHT with a net left-to-right shunt
Complications - endocarditis, aortic regurgitation, RVOT obstruction

All patients

Lifelong ACHD specialist follow-up
Endocarditis prophylaxis - prosthetic material for the first 6 months, or residual shunt adjacent to a patch
Pregnancy counselling; pregnancy contraindicated in Eisenmenger

Associations

Primum ASD - Down syndrome, cleft mitral valve with MR, TR, coexisting VSD
Sinus venosus ASD - partial anomalous pulmonary venous return
Secundum ASD - Holt-Oram syndrome, MVP
VSD - Down syndrome, Turner syndrome, tetralogy of Fallot
Perimembranous/outlet VSD - aortic regurgitation from leaflet prolapse
Post-MI VSD

Natural history & complications

Small restrictive defects - normal life expectancy, but endocarditis risk persists
Unrepaired significant ASD - AF/flutter and RV failure from the 4th decade onwards
Progression: PHT -> Eisenmenger -> cyanosis, erythrocytosis, paradoxical embolism
Post-MI VSD is a different disease - very high mortality, urgent surgical or device closure

Monitor

RV size, PASP, residual shunt
Arrhythmia
Functional status

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