Ventricular septal defects

1. Ventricular Septal Defects
-Raja Lahiri

2. Introduction
• A VSD is a defect in the ventricular septum
• Most common congenital cardiac anomalies.
• 3-3.8 per 1000 live births
• 30-60% of all newborns with a CHD
• Prospective studies give a prevalence of 2-5
per 100 births of trabecular VSDs that closes
shortly after birth in 80-90% of the cases

3. MALADIE DE ROGER
• “A developmental defect of the heart occurs from
which cyanosis does not ensue inspite of the fact
that a communication exists between the cavities
of the two ventricles and inspite of the fact that
admixture of venous blood and arterial blood
occurs. This congenital defect , which is even
compatible with a long life, is a simple one. It
comprises a defect in the interventricular
septum.”
Henri Roger, 1879

4. Morphology – The Ventricular Septum
 Complex non – planar structure; 4
components
 Inlet septum – lightly
trabeculated; extends from
tricuspid annulus to attachments
of tricuspid valve
 Trabecular septum – heavily
trabeculated; trabecular septum
extends from inlet out to apex and
up to smooth-walled outlet
 Outlet septum – non trabeculated;
extends up to pulmonary valve&
diverge from small membranous
septum
 Membranous septum only
fibrous component of IVS, wedged
btwn AV, MV, TV.

6. Development of IVS
• Ventricles derived from 2 important
components of primitive heart – inlet & outlet
septum
• Three septal components are necessary for
septation
• Expansion of inlet & outlet components leads
to formation of partial septum between two –
primary interventricular septum

7. • Two intrinsic septum in two
segments called inlet & outlet
septum
• Third component comes from
endocardial cushion tissue –
membranous portion of
ventricular septum
• Septation starts at about 37 days
of gestation & complete by 49th
day of gestation

9. Prevelance
• Most common congenital heart lesion
• Occurs in 50% of children with heart lesions
• 15-20% in isolation
• 5-50 per 1000 live births
• 56% female

10. DEVELOPMENTAL ANOMALIES
• Failure of component development
– Simple VSDs
• Failure of alignment of component
– Anterior and cephalad malalignment e.g. TOF
– Posterior malalignment e.g. Interrupted Aortic
Arch
• Failure of rotation
– Taussig bing anomaly

11. Associated Defects
• Left Heart Defects
– Aortic stenosis
– Coarctation of the aorta
• Right Heart Defects
– Tetrology of Fallot
– Double Outlet Right Ventricle
• Truncus Arteriosus
• Some single ventricle (e.g. Tricuspid atresia)

12. Chromosomal Disorders associated
with VSD
• Trisomy 21: 40% of T21 will have VSD
• Trisomy 13, 18: 18% of T13, 31% of T18 will have VSD
• 22q11 deletion:
– Tetrology of Fallot is most common anomaly
– VSD with or without aortic arch anomaly is second most common
• Holt-Oram (Hand-heart syndrome): TBX5 gene found on
Chromosome 12
• Recurrence risk for VSD based on parental VSD
– Paternal 2%
– Maternal 6-10%

13. CLASSIFICATION
• CLASSICAL
• SOTO
• VAN PRAAGH
• ANDERSON
• MORPHOLOGICAL (congenital heart surgery
nomenclature & database project)

14. Classic classification
CONAL
PARAMEMBRA
NOUS
ATRIOVENTRIC
ULAR CANAL
MUSCULAR

15. Van praagh classification
CONAL
CONOVENTRIC
ULAR
AV CANAL
MUSCULAR

16. Anderson classification
PERIMEMBR
ANOUS
DOUBLY
COMMTTTE
D
MUSCULAR

17. EXPANDED classification (KIRKLIN)
 Classification Extension
1. Perimembranous inlet
outlet
anterior
2. Muscular outlet/conal
trabecular
inlet
anterior
apical
3. Doubly committed subarterial
4. Inlet septal AV septal type
5. Malalinged Ant (TOF)
Post(INTERRUPTED AORTIC ARCH)
Rotational (Taussig bing)

18. Hemodynamic classification
• Restrictive
• Moderately restrictive
• Non restrictive

19. – Restrictive- resistance that limits the shunt at the
site of vsd
– < 0.5 cm2 (Smaller than Ao valve orifice area)
– Small L to R shunt
– Normal RV output
– 75% spontaneously close < 2yrs
LVSP > RVSP
pulm /aortic systolic pressure ratio < 0.3
Qp / Qs<1.4--1

20. • Moderately restrictive - RVSP high, but
less than LVSP
• Qp/Qs 1.4--2.2

21.  Non restrictive -Shunt not limited at the site of
defect
– > 1.0 cm2 (Equal to or greater than to Ao valve
orifice area)
– Large hemodynamically significant L to R shunt
– Rarely close spontaneously
-RVSP , LVSP, PA , Aortic systolic
pressures equal
- Qp/Qs >2.2
- Flow determined by PVR

22. CLASSIFICATION OF VSD
According to the size of lesions
Small Size Medium Size Large Size
Diameter (mm)
Size (cm2)
<5
<0.5
5~15
0.5~1.5
>15
>1.0
Shunt small medium large
Symptom Non or little some Obvious
Pul. Vessel No affection affected Pul. Arterial
Hypertension
Eisenmenger’s
syndrome

23. • Defect size is often compared to aortic
annulus
– Large: > 75% of annulus size
– Medium: 75-33% of annulus size
– Small: <33% of annulus size

24. • Atrioventricular canal type VSD
• Muscular VSDs: midventricular
(1), apical (2), anterior (3), and
posterior (4)
• Conoventricular septal defect,
which includes
perimembranous and
malalignment conoventricular
septal defects
• Conal septal defects.

25. Conoventricular (Membranous)
Defects
• Conoventricular defects are located between the conal
septum and the ventricular septum.
• They are centered in or around the membranous
septum and comprise 80% of all VSDs.
• Located exclusively within the membranous septum, or
can extend beyond the boundaries of the membranous
septum toward inferior, posterior, or anterior
directions, and are then sometimes called
“perimembranous” or “paramembranous” VSDs.

26. • The prefix “peri-,” appearing in loan words from the Greek,
means “surrounding” (i.e., perimeter). As such, a truly
perimembranous ventricular septal defect would surround
the membranous septum.
• In contrast, the prefix “para-,” also from the Greek, means
“adjacent to” or “beside” and more accurately reflects the
notion of a defect adjacent to the membranous septum.
• Neither perimembranous nor paramembranous correctly
describes the typical defect involving the membranous
septum and extending into the adjacent septum.

27. • The current recommendation is to call these defects either
membranous VSDs or conoventricular defects.
• Malalignment of the conal septal plane vis-à-vis the
ventricular septal plane results in the typical
conoventricular defect.
• The malalignment can be anterior, as seen in tetralogy of
Fallot, or posterior, as seen in interrupted aortic arch.
• Anterior conal septal malalignment also results in RVOT
• Posterior malalignment of the conal septum results in LVOT.

28. • Important landmarks in conoventricular septal defects are
the anteroseptal commissure of the tricuspid valve
inferiorly and the noncoronary cusp of the aortic valve.
• When the ventricular portion of the membranous septum
is entirely absent, the VSD extends to the base of the aortic
valve (sometimes called “subaortic” VSD).
• The medial papillary muscle (muscle of Lancisi) located at
the inferior–posterior border of the defect is also an
important landmark.
• Both the septal and anterior tricuspid valve leaflets are
attached to it.

29. Conal Septal Defects
• Approximately 8% of VSDs are located in the
conal (infundibulum or outlet) septum.
• They also are called supracristal VSDs.
• They are either entirely surrounded by muscle
(muscular conal VSDs) or limited upstream by
the aortic or pulmonary annuli (sometimes
called subarterial VSDs).

30. Inlet (Atrioventricular Canal Type) VSD
• This defect is characterized by the absence of
part or all of the inlet septum.
• The VSD is located immediately underneath
the septal leaflet of the tricuspid valve with no
tissue in between.
• Approximately 6% of all VSDs are inlet-type
VSDs.

31. Muscular VSDs
• Muscular VSDs (10% of all VSDs) are entirely surrounded by
muscle.
• They can occur anywhere in the trabecular portion of the
septum and can be isolated or multiple.
• They are described by their location, that is, anterior,
midventricular, posterior, or apical.
• When inspected through the left side of the septum, what
appeared to be multiple muscular defects often converge
into either a single hole or two separate holes.

32. PATHOPHYSIOLOGY
• Blood flow dependent on multiple factors
–Small and restrictive
• Lesion size
–Large and non-restrictive
• Balance between pulmonary and
systemic vascular resistance
size
Pulmonary vascular
resistance
systemic vascular
resistance

33. HEMODYNAMICS OF VSD
VSD shunt
Pulmonary
plethora
PA congestive
RV
RA
SVC, IVC
Increased volume of blood
in pulmonay circulation
LA enlargement
LV enlargement
Aorta ejects less blood
Systemic
circulation
insufficiency

34. Natural history
 Spontaneous closure :75-85 % all VSDs
• :35% perimemb ( 1st 6/12)
• Spontaneous closure by age 1month—80%
• 3 months--- 60%
• 6 months--- 50%
• 12 months__ 25%
 More frequent in small defects
 Decrease in size with age
 Inlet & outlet defects do not become smaller /close spont
 Large & nonrestrictive defects : 10- 15%
o Endocarditis – risk of endocarditis 4-10% for the first 30 years of life
→high velocity turbulent jet into RV

35. CHF - Large VSDs
Mod sized VSDs survive into adulthood
Increased rt sided flow  pulmonary vascular
disease  Eisenmenger’s physiology if left
untreated

36. Mechanisms of closure
Growth & hypertrophy of septum around the
defect
By development of subacute bacterial endocarditis
Adherence of leaflet tissue to the margins
• (Negative pressure effect exerted by a high
velocity stream flowing through the defect )
Ventricular septal aneurysm
Prolapse of aortic cusp
Intrusion of a sinus of valsalva aneurysm

37. VSD THAT DON’T CLOSE
1. perimembranous (malaligned)
2.juxta aortic,
3. inlet:av septal type,
4.perimembranous (Gerbode defect)

38. Commonly Associated Defects
• Patent Ductus Arteriosus
• Aortic Coarctation
• Left Ventricular Outflow tract Obstruction
• Large atrial septal defects
• Right ventricular outflow tract obstruction
• Persistent left superior vena cava

39. Patent Ductus Arteriosus
• In symptomatic neonates or infants with VSDs, a large patent
ductus arteriosus (PDA) is present in about 25% of cases.
• Preoperative echocardiography may fail to show a PDA in the
presence of a large amount of left-to-right shunting.
• Intraoperative TEE is notoriously unreliable in excluding PDAs.
• Therefore the possibility of a PDA should be kept in mind while
approaching a VSD, and if there is any doubt, or if there is a large
amount of backflow through the pulmonary arteries on
cardiopulmonary bypass
• The PDA should be ligated or clipped.

40. Aortic Coarctation
• A hemodynamically significant aortic
coarctation is present in approximately 10% of
cases.
• Because of the unique pathophysiology here
(more left-to-right shunting across the VSD
because of increased afterload caused by the
coarctation), these patients usually have
presenting symptoms before 3 months of age.

41. Left Ventricular Outflow Tract
Obstruction
• Congenital valvar or subvalvar aortic stenosis is
seen in approximately 4% of patients requiring an
operation for VSD.
• The most common type of subaortic stenosis
associated with VSDs is the discrete
fibromuscular membrane of the VSD that is
located inferior or upstream to it.
• Congenital mitral valve stenosis is rare and occurs
in about 2% of patients.