Ventricular Septal Defect in Fetus and Children

A ventricular septal defect (VSD) is a communication between the left and right ventricles. It can occur as an isolated defect or associated with other congenital heart lesions. It is the most common genetic heart abnormality accounting for about 17% to 37% of all such defects. The incidence ranges from 5 to 50 per 1,000 live births. The incidence rates are not related significantly to race, sex, maternal age, birth order, or socioeconomic status. VSD is more common in premature infants and those born with low birth weight. It is slightly more common in females (56%).

Salient Features

Naima 8 years old girl, the only issue of her non-consanguineous parent, hailing from Faridpur, was immunized as per the EPI schedule, admitted with complaints of repeated respiratory tract infection which occurred 4-5 times per year and required hospitalization two times and not growing well. For these complaints, she visited a registered physician and was diagnosed with CHD, and was treated with some medication, but her condition did not improve. So subsequently she was referred to the pediatric cardiology department, at BSMMU. She has no H/O cyanosis, dyspnoea, palpitation, edema, or fever.

The child is well-alert, afebrile, acyanotic, and non-edematous. Vital signs are within normal limits. Anthropometrically she is moderately wasted. Precordium has bulged, visible apex beat. Apex beat is situated at the left 5th intercostal space just lateral to the midclavicular line which is thrusting in nature, with thrill present. There is a pan systolic murmur best heard in the lower left sternal edge with grade 4/6 and no radiation. Other systemic examination reveals normal findings.

So, the provisional diagnosis is acyanotic congenital heart disease – Most probably a ventricular septal defect.

Points in favor of VSD

• Acyanotic
• Thrusting apex beat
• Pansystolic murmur in the lower left sternal edge.

Congenital Heart Disease in Children

Etiology of VSD

Multifactorial: Genetic and Environmental

Genetic: Aneuploidy syndromes such as Trisomy 13, 18, and 21

Environmental:  Exposure to certain environmental factors during pregnancy like-

• Radiation, Smoking
• Maternal phenylketonuria, Diabetes Mellitus
• Exposure to febrile illness, especially rubella infection
• Teratogens like alcohol, cocaine, marijuana, ibuprofen, anticonvulsants (hydantoin, carbamazepine), or organic solvents.

Some diseases are associated with VSD such as

• Down syndrome
• Edward syndrome
• Cri – du –chat syndrome
• Infant of Diabetic mother
• Congenital rubella syndrome

How the Interventricular septum develops in the fetus

It has mainly two parts. The thick, muscular tissue is derived from the walls of the growing ventricles. When this muscular septum is complete, a large opening  (the Interventricular foramen) still remains between the two ventricles.

• Muscular part
• Membranous part

The interventricular foramen is usually completely closed by the 7th week. The closure is accomplished by the growth of membranous tissue derived from the endocardial cushions, the interventricular septum, and from the conus ridges formed within the truncus and extending to the Interventricular septum.

Types of VSD

Types based on anatomic site.

1. Peri-membranous defect: These defects are in a postero-inferior position of the left ventricle, anterior to the septal leaflet of the tricuspid valve. Most common type(70-80%)
2. The outlet or supra cristal defect: (5-30%) is situated superior to the crista supraventricular; just beneath the pulmonary valve. May be associated with pulmonary stenosis and other manifestations of tetralogy of Fallot.
3. The muscular defect: (5-20%) VSDs in the mid-portion or apical region of the ventricular septum are muscular in type and may be single or multiple (“Swiss cheese” septum).
4. The inlet or endocardial cushion defect: lies high (5-8%)

Pathophysiology of VSD

Two determinants: 1. Size of defect  2. Pulmonary vascular resistance

These determine

• Direction of flow
• Amount of flow.

After birth PVR falls…..Large flow across shunt if large VSD. Causes increased PA pressure (initially flow related), and increased PV return, hence LA enlargement, and LV overload in diastole occurs. As the VSD is large, blood does not stay in the RV, but rather uses it as a transit passage. So LV enlargement occurs.

The VSD permits a left-to-right shunt to occur at the ventricular level. A left-to-right shunt at the ventricular level has the following hemodynamic consequences:

• Left ventricular volume overload
• Increased pulmonary blood flow
• Compromise of systemic cardiac output.

The severity of pulmonary vascular obstructive disease correlates to the size of the shunt. In time, as PVR increases,  irreversible histologic changes may occur within the pulmonary vascular bed. If untreated, a reversal of the flow occurs, leading to a right-to-left shunt with the development of increasing cyanosis  (Eisenmenger complex).

After birthing in patients with a large VSD, PVR may remain elevated, delaying the normal postnatal decrease, and thus the size of the left-to-right shunt may initially be limited. PVR begins to fall in the 1st few weeks after birth, and the size of the left-to-right shunt then increases. So the baby may be asymptomatic during the first few weeks of life. Eventually, a large left-to-right shunt develops, and clinical symptoms become apparent. In rare infants with a large VSD, more often in those with Down syndrome, PVR never decreases, and symptoms may remain minimal until Eisenmenger’s physiology becomes evident.

Clinical Features of VSD

Small VSD (Restrictive):

• Patients usually remain asymptomatic with near-normal growth and development
• Incidental detection of a loud, harsh, or blowing pan systolic murmur at left 3rd and 4th intercostal spaces, accompanied by a thrill

Large VSD (Non-restrictive):

• Symptoms usually develop in early infancy (2nd & 3rd month of life)
• Dyspnoea at rest/ during feeding or on exertion
• Poor feeding/interrupted feeding
• Poor weight gain (failure to thrive)
• Easy fatigability
• Profuse perspiration (diaphoresis) e.g. head sweating
• Recurrent respiratory tract infections
• Symptoms of HF may be present

Physical Examination findings in VSD

• Appearance: Sick looking, often malnourished
• Cyanosis is usually absent but duskiness is sometimes noted during infections or crying (cyanosis may be present in severe pulmonary vascular resistance & right to left shunt)
• Respiratory rate: Increased
• Pulse rate: Increased, Volume: Good
• Blood pressure: Normal
• Jugular venous pressure: May be raised in CCF
• Pedal edema: Absent, but may present in CCF

Precordium Examination:

Inspection: Precordium may have bulged, Hyperdynamic.

Palpation:

• Apex beat shifted and thrusting-LVH 
• Systolic Thrill: May be present
• Left parasternal heave may be present if PHTN and RV hypertrophy
• P2: May be palpable if PHTN

Auscultation:

1st and 2nd heart sounds are audible in all 4 areas (2nd HS may be merged with pansystolic murmur)

A harsh pan-systolic murmur (grade 4/6) is best heard at the lower left sternal border at the 3rd, 4th & 5th intercostal spaces. The murmur may radiate to the right lower sternal border. Intensity varies based on the size of the VSD and pulmonary vascular resistance.

A soft mid-diastolic murmur over the apex indicates pulmonary to systemic blood flow ratio is at least 2:1.

The sound of murmur is more in small VSD than large due to the absence of a significant pressure gradient across the defect.

The premature baby with VSD: murmur is heard early because pulmonary vascular resistance decreases more rapidly.

Investigations to Diagnose VSD

1. Chest Xray
2. ECG
3. Echocardiography
4. Cardiac Catheterization.

Chest Xray:

In small VSD: mild Cardiomegaly (cardiothoracic ratio >60%) or normal
In large VSD: Cardiomegaly (left or biventricular enlargement, the left atrium, and the pulmonary artery. Pulmonary vascular markings are increased, and frank pulmonary edema, including pleural effusions, may be present

ECG Findings:

Small VSD, the ECG findings are normal.

Moderate VSD left ventricular hypertrophy (LVH) and occasional left atrial hypertrophy (LAH) may be seen.

Large defect, the ECG shows biventricular hypertrophy (BVH) with or without LAH.

If the pulmonary vascular obstructive disease develops, the ECG shows RVH only.

Echo findings

2D Echo: Site, size & number of septal defects. Chamber size (left ventricular hypertrophy).

Color Doppler Echo: Presence & direction of the shunt. Prediction of pressure in the right-sided chambers by measuring by QP/QS flow ratio.

Cardiac Catheterization

• To assess the operability of VSD.

• Quantification of shunting.

• Assessment of pulmonary pressure and resistance.

• Evaluation of other lesions such as  AR, double chamber RV.

• Determination of multiple VSD.

• VSD anatomy especially if device closure is contemplated.

Treatment of Ventricular Septal Defect:

For Small VSD

Counsel parents that it is a relatively benign lesion

• Require no surgery, even no treatment
• Can close spontaneously in 30-50% of cases by 2 years of age
• Advice for: Normal foods and No restrictions on physical activities
• Infective endocarditis prophylaxis
• Follow-up: These patients can be monitored by a combination of clinical examination and non-invasive laboratory tests until the VSD has closed spontaneously.

Moderate to Large VSD: Less likely to close spontaneously

• Adequate nutrition, High-calorie diet to ensure normal growth.
• Maintain good dental hygiene
• Antibiotic prophylaxis for IE
• Prevention of repeated RTI, Anaemia
• Chest infection and CCF should be treated if present.

Drug Treatment: Usual drugs used are diuretics, digoxin, and afterload-reducing agents (Captopril, enalapril). Recommended in VSD with progressive pulmonary vascular diseases.

Diuretics

• Mainstay of medical therapy.
• These relieve ventricular overload and peripheral and pulmonary congestion.
• Furosemide (Lasix): 1-3 mg/kg/day in 2-3 divided dose
• Spironolactone: 1 mg/kg/dose

Digoxin:

• Positive inotropic agent augments myocardial contractility. 
• Digitalization: 20-40 mcg/kg
• Maintenance: 5-10 mcg/kg/day

Afterload reducing agents

• Enalapril  :    0.1-0.5 mg/kg/day 1-2 doses.
• Captopril:   0.5-1 mg/kg/day [Max 6mg/kg]  2-4 divided doses.

Indications for Surgery

• Patients at any age with large defects in whom clinical symptoms & failure to thrive can not be controlled medically.
• Infants between 6-12 months with large defects associated with pulmonary HTN, even if the symptoms are controlled by medication.
• Patients older than 24 months with a Qp: Qs ratio greater than 2:1
• Supracristal VSD of any size.

Time of surgery:

At the age of 3-6 months. Mostly before 1 year.

Complications of VSD

• Growth failure
• Recurrent RTI
• Congestive heart failure
• Pulmonary vascular disease as a consequence of left-to-right shunting (Eisenmenger syndrome or  complex)
• Infective endocarditis
• Aortic regurgitation

How to Prevent VSD in the fetus

1. Early prenatal care, even before getting pregnant. See here Pre Pregnancy Care Medical Tips & Tests Before Getting Pregnant
2. Take a multivitamin with folic acid
3. Avoid drinking alcohol
4. Don’t smoke or take any heroin, cocaine, or illegal drugs.
5. Keep diabetes under control
6. Vaccinate yourself.

Further Study

Facts about Ventricular Septal Defect CDC

Maternal lifestyle factors in pregnancy and congenital heart defects in offspring: a review of the current evidence Link

The pattern of Congenital Heart Diseases and Treatment Options in a Bangladeshi Centre: Analysis of 6914 cases from Non-invasive Cardiac Laboratory PDF Download

Thanks