Transcript Ventricular Septal Defects

Ventricular Septal Defects
• 1 in 1000 live births
• 50% associated with other congenital
malformations
• First described by Roger in 1879, hence
small VSDs are also known as the ‘maladie
de Roger’.
• First VSD closed under direct vision by
Lillehei in 1955
Ventricular Septum
• Components
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Membranous septum
Outlet or conal septum
Inlet septum or the septum of the A-V canal
Muscular or trabecular septum
Anatomy of ventricular septum as seen from RV side
Anatomic Classification of VSDs
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Perimembranous
Subarterial or outlet
A-V canal or Inlet
Muscular
Anatomy of ventricular septum as seen from RV side
Perimembranous VSD
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Also called conoventricular defects.
Most common (80%)
Margins include membranous septum or remnant
May have extensions into inlet, outlet or trabecular
septum
• Postero-inferior margin very close to the anteroseptal commissure of the Tricuspid valve
• Can extend upto non-coronary cusp of aortic valve
Perimembranous (Conoventricular VSD)
Subarterial VSDs
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Also k/a outlet, conal, subpulmonary, supracristal
Located in the outlet septum
5 – 10% of VSDs
Can extend upto right or sometimes non-coronary
cusps of the aortic valve, hence cause AR
Subarterial VSD
A-V canal or Inlet VSDs
• In the inlet part of the septum, usually spanning
the length of the septal leaflet of the TV
• < 5% of surgically treated VSDs
• The posterior rim of the defect runs along the
septal leaflet of the TV to the central fibrous body
and the AML (which may have a cleft in
association).
• No intervening muscle between the VSD and the
tricuspid valve
Inlet VSD
Muscular VSDs
• Muscle tissue all around the defect
• According to their location they may be either anterior, in
the inlet septum, mid-muscular or apical
• Classification according to location is important because it
determines the approach for surgical closure.
– Inlet and mid-muscular ----- RA approach
– Anterior ------- Rt. Ventriculotomy
– Apical ------ May require left ventriculotomy
• May be multiple
Atrioventricular conduction system
• AV-node -------- Triangle of Koch
• Bundle of His ------ through CFB in close relation to both
the tricuspid and aortic valves
– Along inferior border of the membranous septum
– Left ventricular side of muscular IVS
• Perimembranous VSD ----- Conduction tissue along
postero-inferior rim of the defect
• Inlet VSD ----- AV node migrates posteriorly towards the
crux of the heart, hence the conduction tissue lies along the
postero-inferior margin again
• Subarterial VSD ---- Muscle tissue between rim of VSD
and conduction tissue
• Muscular VSD ----- Conduction tissue is in normal
anatomic position. Separated from rim by muscular tissue
Pathophysiology
• Two determinants
– Size of defect
– Pulmonary vascular resistance
• These determine
– Pressure gradient across VSD
– Shunt volume across VSD
• After birth PVR falls ------ Large flow across shunt if large
VSD
• Causes increased PA pressure (initially flow related),
increased PV return, hence LA enlargement and LV
overload
• PH initially flow related and reversible
Pathophysiology
• Later ----- Intimal proliferation and medial hypertrophy
leads to fixed irreversible PH
• Flow through the lungs decreases as PVR increases, hence
shunt volume decreases
• Eventually PVR > SVR, hence R  L shunt across VSD
Cyanosis  Eisenmengerised VSD
• Shunt calculated by Fick’s principle Qp/Qs
Aortic O2 % sat - Central Venous O2 % sat
Pulm. Vein O2 % sat – Pulm. Art O2 % sat
• With small VSDs, there is resistance to flow across the
VSD hence Qp/Qs is rarely > 1.5
• With moderate VSDs, Qp/Qs is between 1.5 and 2.5, and is
less likely to cause pulm vasc disease
Symptoms & Natural History
• Both depend on shunt volume
• With large VSDs, infants present with respiratory
infections, failure to thrive and heart failure.
• If untreated, 10% will die within first year of life
• If they survive beyond the first year, if untreated, with
eventually develop Eisenmenger complex and die
(Hemoptysis, polycythemia, cerebral abscesses and
infarction and right heart failure)
• Smaller VSDs produce less symptoms, and survival to
older ages is known
• Bacterial endocarditis risk 0.15 to 0.3 % per year
Symptoms & Natural History
• Spontaneous closure is known, primarily with
perimembranous and muscular VSDs. Subarterial
and inlet VSDs rarely
– Chances differ with age at detection
• At 1 month  80% of large VSDs close
• At 6 months  50%
• At 12 months  25%
• AI – with subarterial VSDs or Perimembranous
VSDs with subaortic extensions
Clinical features
• Depends on shunt flow
• Spectrum of symptoms
– Small VSDs rarely symptomatic
– Large VSDs with severe symptoms  failure to thrive,
heart failure, repeated LRTI
• Hyperactive precordium
• Pansystolic precordial murmur
• Signs may change with spontaneous closure of
Eisenmengerisation
Diagnosis
• ECG - Left atrial enlargement, ventricular hypertrophy
• CXR – Cardiomegaly d/t LA enlargement and LV volume
overload
– Increased vascular markings (plethoric lung fields)
• 2D, Doppler Echo and CF mapping
• Cardiac Cath
– Not routinely performed
– To be considered in older patients to document PA pressure and
PVR
– Can also calculate Qp/Qs, and irreversible component of PH
Treatment
• Treatment dictated by
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Severity of symptoms
Age at presentation
PVR
Size and type of defect
Other co-existing malformations
• Early repair in infancy for intractable HF and failure to
thrive
• With less symptoms, best to wait till 12 months of age for
spontaneous closure
• Thereafter, moderate to large VSDs should be closed
Treatment
• Infants > 6 months, with raised PVR – prompt surgery
• Inlet and subarterial VSDs – early closure
• Surgical approach
– Standard CPB with bicaval cannulation and snaring of Cavae
– In very small infants < 8 kg, circulatory arrest with deep
hypothermia may be best
– RA approach for most VSDs
– Subarterial VSDs may be approached through PV
– Muscular VSDs  approach depends on location
– Usually closed with Veloured Dacron or Goretex patches
– Interrupted or continuous sutures
Treatment
• Damage to conduction tissue avoided by
– Placement of sutures a few mm away from the rim on the right
ventricular side of the septum, in the region of proximity to the
– Where there is no tissue between the rim of the VSD and the
tricuspid valve, sutures are placed on the base of the tricuspid
septal leaflet
Results
• Early mortality approaching 0% in specialised centers
• Patients operated late, with high PVR have worse longterm outcome
• Conduction disturbances
– CHB approaching 0% in specialised centers
– RBBB  30 – 35% with RA approach, higher if RV approach
• Residual defect  1 – 2%