Ventricular Septal Defect (VSD) is the most common form of congenital heart disease,
if bicuspid aortic valve is excluded. It is a defect in the ventricular septum which
separates the two ventricles and can occur in any part of ventricular septum. Roger
H provided the first clinical description of VSD in 1879.
Isolated VSD accounts for approximately 20 % of all congenital heart defects with
reported prevalence of 0.3 – 3.3 per 1000 live births 2-5. VSD is more common among
preterm infants and stillborns as compared to term infants. The prevalence of VSD
is lower in adults due to spontaneous closure of many defects. VSD’s are most common
congenital cardiac lesion found in association with various chromosomal syndromes
including trisomy 13, trisomy 18, trisomy 21 and others 6.
Ventricular septal defect results from a delay in closure of the interventricular
septum beyond the first 7 weeks of intrauterine life. The reason for this delayed
or incomplete closure is still unknown. The normal development of interventricular
septum depends upon the endocardial cushions, conotruncal ridges, growth of tissues
at the crest of interventricular septum and muscular septum. VSD occurs as a result
of maldevelopment of one or more of these structures.
Ventricular Septal Defects can be present in any part of interventricular septum
and are hence classified according to their anatomical location.( Figure 1).
A. Perimembranous VSD : These are the most common type of ventricular septal
defects and account for approximately 80 % of the VSD’s. They involve the membranous
part of ventricular septum which lies in the outflow tract of the left ventricle
immediately beneath the aortic valve. They usually extend into muscular, inlet or
outlet portion of ventricular septum. B. Inlet VSD : These VSD account for
5 to 8 % of all the VSD's. They are located posteriorly and inferior to perimembranous
portion of ventricular septum.
C. Subarterial VSD or Doubly committed VSD or Subpulmonary VSD : These VSD
account for 5 to 7 % of all the VSD’s. They are located just beneath the pulmonary
D. Muscular VSD : These VSD account for 5 to 20 % of all the VSD’s and are
further subclassified depending on their location in the muscular septum.
i) Central : Located in the mid-muscular part of the ventricular septum with
multiple apparent channels on right ventricular side and single defect on the left
ii) Apical : Located in the apical part of the ventricular septum with multiple
apparent channels on right ventricular side and single defect on the left ventricular
iii) Swiss Cheese : Multiple muscular defects in the ventricular septum.
Fig 1 : Anatomical Position of various types of VSD's
Defect in the ventricular septum results in communication between the systemic circulation
and the pulmonary circulation or left to right shunt. The magnitude of left to right
shunt is determined by a) size of the defect and b) Pulmonary vascular resistance.
VSD’s can be divided into three categories : small, moderate and large based on
both the size of defect and pulmonary vascular resistance. Small defects limit the
magnitude of left to right shunt and restrict pressure elevation in the right ventricle.
The left to right shunt is small and right ventricle and pulmonary artery pressures
are normal in such patients. Moderate defects offer resistance to pressure but usually
little resistance to left to right flow. The left to right shunt is moderate and
right ventricle and pulmonary artery pressures are mild/moderately elevated in such
patients. Large defects do not offer any resistance to left to right shunt and hence
results in large left to right shunt and equalization of pressures in the ventricles.
Large left to right shunt results in increased flow in lungs ( Increased Pulmonary
blood flow) which leads to increased pulmonary venous return to left atrium causing
left atrial and ventricular volume overload. The right ventricular pressures are
elevated to the same level as left ventricular pressure resulting in severe pulmonary
arterial hypertension. Although as mentioned above large left to right shunt results
in over circulation in pulmonary bed , left ventricular volume overload and pulmonary
arterial hypertension it needs special mention that if a large VSD is left unattended
in the presence of pulmonary arterial hypertension for prolonged duration ( 1 year
or more) may result in some irreversible hypertrophy of muscles in the medial wall
of pulmonary arterioles . This can progress further to reach a stage when the shunt
reverses to right to left and render the patient inoperable.
The clinical presentation of ventricular septal defects is diverse varying from
patient with no symptoms to those with manifestations of congestive heart failure
(CHF). The wide spectrum of symptoms and physical findings depends in most cases
upon three main factors a). The size of defect, b) Magnitude of left to right shunt
and c) Degree of pulmonary arterial hypertension . However presence of any acquired
conditions resulting from the presence of VSD itself like aortic regurgitation secondary
to aortic valve prolapsed , aneurysm of the ventricular septum, acquired left ventricular
outflow tract obstruction and right ventricular outflow tract obstruction can produce
symptoms out of proportion to those expected from the effective size of defect and
magnitude of left to right shunt.
A. Small VSD : These are most commonly not associated with any symptoms.
The magnitude of blood shunting from left ventricle to right ventricle is small
with no increase in the right ventricular pressure. Most often they are referred
because of murmur detected on routine examination for some incidental illness. The
murmur of small VSD is most often detected around 2 to 6 weeks of age. The murmur
is not heard just after birth and during first few weeks because of high pulmonary
vascular resistance present at birth which declines gradually over next 2 to 6 weeks.
These usually do not interfere with feeding and normal weight gain. The cardiac
examination usually reveals a systolic thrill along the left sternal border . The
first heart sound may be masked by presence of a harsh, holosystolic murmur heard
grade 4/6 heard best along the left lower sternal border. Second Heart sound (S2)
is normally split. Small VSD’s do not produce any diastolic murmur.
B. Moderate Size VSD : Moderate sized VSD’s usually produce murmur between
2 to 6 weeks after birth. The appearance of murmur usually precedes the symptoms
such as mild tachypnea, excessive sweating, feeding difficulties, inadequate weight
gain and at times frequent episodes of chest infections. Decline in rate of weight
gain occurs most commonly between 2 to 4 months. Physical findings in moderate sized
VSD’s include increased intensity of precordial impulse , normal first heart sound
and narrow split second heart sound with increased intensity of P2. Third heart
sound (S3) is present if magnitude of left to right shunt is > 2:1.A harsh pansystolic
murmur best heard at lower left sternal border is present. A low pitched mid diastolic
rumble occurring due to increased flow across the mitral valve indicates that the
shunt is > 2 : 1.
C. Large VSD’s : Large VSD’s usually present around 6 to 8 weeks with symptoms
of poor weight gain, frequent respiratory tract infections and excessive sweating
as the pulmonary vascular resistance falls by this period. The physical findings
include presence of tachypnea, tachycardia and hepatomegaly. The precordial activity
is increased with parasternal lift. Second heart sound is narrowly split but split
is detectable in most patients. A low pitched ejection systolic murmur grade 3/6
is present along with a mid diastolic rumble. Pulmonary component of second heart
sound is accentuated. The above mentioned findings are true for children presenting
in early to late infancy but those presenting at a later age with pulmonary vascular
obstructive disease usually do not have respiratory complaints but are mildly cyanosed
with often clubbing of the fingers. In such patients the systolic murmur is short
if at all present , P2 is loud banging with a short early diastolic murmur of pulmonary
regurgitation ( Graham Steele’s murmur).
There are certain associated conditions arising because of VSD itself and these
include a) secondary aortic regurgitation b) subaortic obstruction c) right ventricular
outflow tract obstruction and d) Ventricular septal aneurysm.
Aortic Regurgitation can occur in both doubly committed VSD and perimembranous VSD’s.
In the former it is due to poorly supported right coronary cusp while in the latter
due to maldevelopment of aortic commissures. Discrete subaortic obstruction may
represent an incidental association or as a result of malaligned septum. This can
sometimes result in left ventricular outflow obstruction. Right ventricular outflow
obstruction occurs in 3 to 7 % patients and is due to hypertrophy of anomalous muscle
bundles. Aneurysm of ventricular septum often occurs in perimembranous VSD’s and
is considered responsible for decrease in size or spontaneous closure of these VSD’s
RADIOLOGICAL FEATURES The radiological features are variable in VSD depending
upon the magnitude of left to right shunt and degree of pulmonary arterial hypertension.
In Small VSD’s the chest roentgenogram is usually normal (Fig 2). Moderate VSD’s
are associated with increase in cardiac silhouette , prominent left ventricular
contour, left atrial enlargement ( evidenced by uplifting of the air column of the
left main bronchus and enhancement of pulmonary vascular markings (Fig 3). Large
VSD’s produce marked cardiomegaly, left atrial enlargement, pulmonary plethora,
interstitial edema and Kerley B lines ( Fig 4). In older children with large VSD
and pulmonary vascular obstructive disease the heart size decreases but enlargement
of pulmonary trunk persists and lung fields appear oligaemic ( Fig 5).
Fig 2 CXR of a Small VSD
Fig 3 CXR of a Moderate VSD
Fig 4 CXR of a Large VSD, ↑ PBF Fig 5 CXR of a VSD with Eisenmenger
The Electrocardiogram reflects the hemodynamic and the trace are influenced by the
size of defect and pulmonary vascular resistance. In patients with small VSD the
ECG is generally normal. However rhythm disturbances such as complete heart block,
atrial fibrillation and flutter are reported in small perimembranous VSD’s with
septal aneurysms. Moderate sized VSD’s produce broad notched P waves with some degree
of left ventricular hypertrophy. Large VSD’s may also manifest evidence of left
ventricular hypertrophy alone but mostly there is combined right and left ventricular
hypertrophy in the midprecordial leads ( Katz-Wachtel phenomenon). In patients with
Eisenmenger syndrome right ventricular hypertrophy is manifested by tall R waves
in Lead V1 while the left precordial Q waves are absent suggesting pressure overload
of Right ventricle. The QRS axis is generally normal in small and moderate sized
VSD’s while right axis deviation occurs in those with large VSD. Left axis deviation
of QRS can occur in perimembranous VSD with inlet extension and those with formation
of ventricular septal aneurysm. Electrocardiogram provides vital information regarding
the hemodynamic of ventricular septal defect and hence remains an important tool
in the diagnosis as well as management.
Trans-thoracic 2-Dimensional colour Doppler echocardiography is the modality of
choice to evaluate the size, number and anatomical location of most VSD’s apart
from measurement of atrial and ventricular dimensions and estimation of pulmonary
artery pressures. The size of defect can be measured accurately from the 2 dimensional
images. The size of VSD is measured in relation to the size of aorta. The VSDs are
considered as large defect if they are as large as aorta . The VSDs measuring one-third
to two-third of the aortic diameter are considered moderate and those less than
one-third the size of aorta are considered small. The conventional echocardiographic
views like apical 4 chamber view, parasternal long axis view, parasternal short
axis view, subcostal sagittal views provide accurate information regarding the specific
anatomical location of VSD’s. Apical 4 chamber view are helpful in diagnosing inlet
VSD’s, midmuscular and apical muscular defects. Parasternal Long axis view demonstrates
the perimembranous defects with or without formation of septal aneurysms. Para-sternal
short axis view helps in differentiating perimembranous and outlet VSD’s ( located
at 10 -11 o’ clock and 11-12 o’ clock position respectively ) from the doubly committed
VSD’s which are located at1-2 o’ clock position. The interventricular pressure gradient
estimated by Doppler echocardiography is useful in predicting the Right ventricular
pressure and the pulmonary artery pressures. Left atrial and left ventricular dimensions
provide information regarding the magnitude of left to right shunt. Echocardiographic
evaluation in patients with VSD should be targeted to identify the presence of associated
anomalies such as straddling or overriding atrioventricular valves, aortic regurgitation,
aortic valve prolapse, ventricular inflow and outflow obstructions. In most clinical
situations echocardiography provides enough information to decide on management
and type of closure of VSD’s., In some clinical situations such as patients with
poor echocardiographic windows trans-esophageal echocardiography may be required
for detailed assessment. Intra-operative trans-esophageal and epicardial echocardiography
is useful in assessing the adequacy of repair and detection of residual defects.
Postoperative echocardiography is helpful in detecting residual lesions and monitoring
the pulmonary artery pressures.
Fig 7 Echocardiographic images of various type of VSD’sCARDIAC CATHETERISATION AND
Cardiac catheterization and selective angiography provides definitive hemodynamic
and anatomical details of VSD’s. In the past cardiac catheterization and angiography
was a standard diagnostic modality but in the last 2 decades non invasive modalities
(especially trans-thoracic and trans-esophageal echocardiography) provide excellent
information and therefore this modality is reserved for children with ill defined
anatomy, associated lesions or those with pulmonary arterial hypertension of unknown
reactivity. The most common indication for cardiac catheterization in the present
era is to assess the response of pulmonary vascular bed to oxygen and other pulmonary
vasodilators like nitric oxide.
Cardiac catheterization is performed to measure the pulmonary blood flow (Qp), systemic
blood flow (Qs), pulmonary vascular resistance ( Rp), systemic vascular resistance
(Rs), Qp/Qs ratio in order to study the hemodynamic alterations. This requires measurement
of oxygen saturations in SVC, IVC, Right atrium, Right ventricle, pulmonary trunk,
pulmonary artery branches, aorta and pulmonary veins respectively and pressure measurements
of right atrium, pulmonary artery wedge, pulmonary artery and aorta. The calculations
are made using the Fick’s Principle. In patients with high pulmonary vascular resistance
(patients with large VSD presenting late, no or borderline cardiomegaly, presence
of short mid diastolic rumble, high Rp at room air) further investigation to assess
the response of pulmonary vasodilators like oxygen and/or nitric oxide is recommended.
This requires administration of oxygen in a concentration of 0.95-1.0 with a tight
fitting mask for 10 minutes and Nitric oxide at a concentration of 10-80 ppm. Though
precise cut off values of pulmonary vascular resistance to ensure safe surgical
outcome is uncertain, surgery is generally advised if PVR decreases to 6-8 wood
Left ventricular angiography documents the location, size and number of VSD’s. The
Long axis oblique view visualizes the conoventricular, midmuscular and apical portions
of the ventricular septum. If the long axis oblique view does not clearly delineate
the defect four chamber views can be performed. Right Anterior oblique view displays
the anterior portion of interventricular septum. Left ventricular angiogram is usually
indicated in patients with poor echocardiographic windows and those with multiple
VSD’s to assess the accurate size of defects since apical muscular VSD are difficult
to be located at the time of surgical correction.
Cardiac catheterization provides us with useful information about the hemodynamic
while angiography provides precise anatomical details of ventricular septal defect.
Although informative the indications for catheterization are limited in the present
The natural history of ventricular septal defects has been widely studied and reported.
Small defects are asymptomatic and rarely need treatment. The spontaneous closure
is reported in approximately 40 % cases being much more common with small muscular
defects ( approx 80 %). Small VSD is not an indication for surgery and present day
recommendations is medical follow up with bacterial endocarditis prophylaxis. Majority
of small VSD’s close in the first 2 years of life. Moderate and large VSD’s may
close spontaneously but less frequently as compared to small defects. The spontaneous
closure rate in such defects is approximately 8-10 %. Significant proportion of
children with moderate sized VSD need surgical closure between 1 to 5 years of age.
Large VSD may show reduction in size of defect in small proportion of patients but
most need early surgical closure. Pulmonary vascular obstructive disease has been
reported in such defects as early as second year of life. The outcome of patients
with Eisenmenger syndrome is poor both in terms of survival and functional limitation.
Aortic regurgitation secondary to prolapse of aortic valve is well reported and
tends to be progressive especially in association with doubly committed VSD’s. Patients
with moderate and large sized VSD’s occasionally develop significant infundibular
pulmonary stenosis which can progress in severity and require surgical intervention.
A. MEDICAL MANAGEMENT
Children with small VSD are asymptomatic and have excellent long term prognosis
and hence should just receive bacterial endocardial prophylaxis. Children with moderate
to large sized VSD’s develop symptoms due to congestive heart failure and in such
patients a trial of medical therapy is indicated. This usually is needed in patients
with left to right shunt > 2 : 1. With improved surgical results in the present
era surgery is recommended in early infancy if symptoms donot respond to medical
The goal of medical therapy in such patients is to a) Relieve symptoms of congestive
heart failure b) Reduction in risk of respiratory tract infections and c) To ascertain
adequate weight gain.
The treatment of CHF in such patients includes fluid restriction, diuretic therapy,
digoxin, angiotensin converting enzyme inhibitors and caloric supplementation. Oxygen
should be used judiciously to reduce hypoxemia as excessive oxygenation can rather
increase the left to right shunt by reducing the pulmonary vascular resistance.
Diuretic therapy includes furosemide ( 1-3 mg/kg/day) and spironolactone can minimize
the potassium loss. After-load reduction with captopril ( 0.5 -1.0 mg/kg/dose) is
useful in reducing the pulmonary blood flow and systemic resistance. Spironolactone
should not be administered if captopril is already being administered due to risk
of potassium retention. Caloric supplementation including addition of medium chain
triglycerides helps in achieving adequate weight gain. Failure to thrive and non
improvement in symptoms due to congestive heart failure are indications for early
repair of VSD.
Patients with large VSD developing pulmonary vascular disease are inoperable and
require symptomatic therapy and counseling. No specific therapy is available for
such patients although some centres use anti-platelet agents like aspirin. Partial
exchange transfusion is recommended to relieve symptoms secondary to polycythemia.
Surgical Closure of ventricular septal defects is the preferred modality. With improving
cardiopulmonary bypass techniques, infants with weight as low as 2 Kg can undergo
successful repair. Surgical mortality is 2-3 % for single VSD or VSD with aortic
insufficiency and 4-5 % for multiple VSD repair. Pulmonary artery banding is presently
done only in children with multiple VSD’s not amenable to surgical closure and in
those with straddling atrioventricular valves.
Indications of VSD Closure :A) Moderate to large VSD with uncontrolled CHF
, recurrent lower respiratory tract infections or growth failure ( early infancy)
B) Older children with left to right shunt > 2:1
C) Small perimembranous or doubly committed VSD’s with associated aortic
insufficiency require early repair to prevent progression of aortic insufficiency.
D) Small VSD with history of Infective endo-carditis.
Majority of Perimembranous and inlet VSD’s are closed vis transatrial approach while
doubly commited or subpulmonary VSD are best approached via pulmonary artery under
cardiopulmonary bypass. Although majority of VSD’s can be dealt with surgical closure
there are still some situations where surgical closure is not feasible and hence
pulmonary artery banding is done in those situations.
Indications of Pulmonary Artery (PA) Banding :
A. Multiple VSD’s ie presence of some remote large muscular VSD’s
B. Large VSD with straddling AV Valve
C. Extremely small infants ( Varies from centre to centre).
Disadvantages of PA Banding include early operative mortality, need for two surgeries,
subaortic stenosis and technical difficulty involving debanding at time of second
In the recent years muscular VSD and lately perimembranous VSD have been closed
with transcatheter approach. This however can be done in selected cases only. The
major advantage of these procedures is no surgical scar, less hospital stay and
avoidance of cardiopulmonary bypass. The limitations of the procedure are proper
case selection, risk of device embolisation and its feasibility in children > 8-10
Kg in weight. Amplatzer’s muscular and perimembranous VSD devices have been used
with good initial results. The procedure is accomplished via femoral approach and
in some cases jugular venous approach.
Latest development in the management of VSD includes a combined surgical and non
surgical approach. This is useful especially in infants with lower weight since
transcatheter approach is not feasible in small infants. In this approach sternotomy
is done but thereafter VSD Device is deployed via purse string suture on right ventricle.
The major advantage of this procedure is avoidance of cardiopulmonary bypass, less
blood loss and speedy post operative recovery since it is accomplished on the beating
heart. This modality is still not a routine procedure but holds a lot of promise
for the future.
Guidelines for management during follow up of children with VSD
Indication for Surgery
1. < 6 mo
Uncontrolled CHF , Failure to Thrive
2. 6 – 24 mo
Pulmonary Hypertension , Symptoms
3. 2 – 5 yrs
Qp/Qs > 2 : 1 , Aortic Regurgitation
4. > 5 yrs
SURGICAL RESULTS AND LONG TERM OUTCOME
The surgical results in the present era are gratifying. The mortality in patients
with VSD is < than 2-3 %. This is mainly attributable to improved cardiopulmonary
bypass technique and post operative care. Immediate complications encountered after
Surgical closure of VSD include a) Residual Left to right shunt , b) Non regression
of Pulmonary arterial hypertension, c) Ventricular dysfunction and d) AV Block.
Long term results are excellent in patients operated at appropriate time . Post
surgery infants show improved growth, weight gain remain symptom free and lead normal
lives. Children with large VSD operated late tend to have residual pulmonary arterial
hypertension and may not fair well in contrast to those treated at ideal age.Bacterial
endocarditis prophylaxis is not recommended after repair if there is no residual
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