VSD in a 3 month old

Images Hanaho Imamura, text Genevieve Carbonatto

A 3 month old girl is brought into the Emergency department. Her parents state that she has become more unsettled recently, not feeding as well and  appearing to be more short of breath with feeding. She is not settling with feeding, requiring to be fed every 2 hours and taking only 100 mls at a time rather than her usual 160mls every 4 hours. Saturations 100% on room air. BP recording of upper and lower limbs similar. No hepatomegaly, no oedema. On examination she has a loud systolic murmur, loudest at the left sternal edge. Prenatal ultrasound normal.

This is her point of care ECHO

PLAX with and without Doppler

Area of green shows flow turbulence at that point

4CV with and without Doppler

Subcostal view

VSD closed

VSD open

A  VSD is diagnosed on ECHO. Because the patient is not in heart failure, is saturating well and not desaturating with feeds, she is referred to cardiology for review and ongoing management.

Discussion

Physical and clinical presentation of VSD

  • Depends on the size of the shunt
  • Murmur – pansystolic in left lower sternal border. Hard and loud in small defects, softer in large defects
  • If AR present : diastolic decrescendo murmur and wide pulse pressure
  • HF: tachypnea, tachycardia (>150/min), diaphoresis with feeding, prolonged feeding time, failure to thrive in infants. Hepatomegaly. Peripheral oedema. Full blown CHF rarely presents in the first week of life but usually at 6 –  8 weeks as the volume of the left to right shunt increases as the pulmonary vascular resistance falls.
  • Eisenmenger’s syndrome : (late presentation) cyanosis, desaturation, dyspnea, syncope, secondary erythocytosis, clubbing

Ventricular Septal Defect (VSD)

  • Most common congenital cardiac abnormality in children  (incidence of isolated VSDs in children 0.3% of all newborns)
  • Second most common abnormality after bicuspid aortic valve in adults
  • Many VSDs close spontaneously (90%)
  • Frequently isolated defect
  • Can occur in association with other congenital abnormalities  such as atrial septal defects (ASDs) , patentductus arteriosus (PDA), right aortic arch, pulmonary stenosis.
  • They are a frequent component of complex congenital heart disease such as tetralogy of fallot and transposition of the great arteries
  • Large defects can lead to pulmonary arterial hypertension (PAH), ventricular dysfunction and increased risk of arrythmias.

Pathology

  • The interventricular system is a complex, non planar structure

Classification (1) :

Due to the complex anatomy there has not been a  unifying classification system for VSDs, however they can be divided largely by their anatomic location

  1. Perimembranous/ membranous: Most common types in adults (80%)  Located in the membranous septum (small fibrous membrane located at the base of the heart and contiguous with the tricuspid – mitral – aortic fibrous continuity)  It often involves the muscular septum when it is commonly known as perimembranous.
  2. Muscular: Most common type in young children ( 5 -10 %) Located in the muscular septum, bordered by muscle usually in the apical, central and outlet parts of the interventricular septum. They can be multiple, assuming a “Swiss cheese” appearance. They represent up to 20% of VSDs in infants. However, the incidence is lower in adults due to the tendency of spontaneous closure.
  3. Inlet : (5%)   Located just inferior to the inlet valves (tricuspid and mitral) within the inlet part of the right ventricular septum.  It is seen in patients with Down syndrome.
  4. Supracristal (outlet) : (5 to 7%)  Located below the semilunar valves (aortic and pulmonary) in the outlet septum of the right ventricle above the crista supraventricularis,  It is the most uncommon type representing only 6% of all VSDs with the exception being in the Asian population where it accounts for approximately 30%. Aortic valve prolapse and regurgitation are common because of loss of support of the right and/or the noncoronary cusps of the aortic valve. It is unusual for these defects to close spontaneously.

Pathophysiology

The degree of shunt between the left and right ventricles and the direction of the shunt determines the haemodynamic significance of the VSD. The factors governing this include

  1. The size of the shunt
  2. the location of the shunt
  3. the pulmonary vascular resistance

The size of the shunt is described in reference to the aortic annulus diameter. It is considered to be

  • small if it is < 25% of the aortic annulus diameter
  • medium if > than 25% but < than 75% of the aortic annulus diameter
  • large if > 75% of the aortic annulus diameter

PAH occurs with long standing large left to right shunts. The pulmonary vascular endothelium undergoes irreversible changes resulting in PAH. When the pressure in the pulmonary circulation exceeds the pressure in the systemic circulation, the shunt direction reverses and becomes right to left. This is known as Eisenmenger’s syndrome and it occurs in 10 – 15% of patients with VSD.

Complications of small shunts

  • Nil if shunt is small. Shunt may close spontaneously in childhood
  • Endocarditis : Triscuspid valve (TV) endocarditis may occur even in small perimembranous VSDs. The tricuspid valve septal leaflet may be affected by the high velocity flow across a small VSD predisposing to endocarditis
  • Double chambered RV: rarely, high velocity jets may impinge on a mid RV muscle bundle causing progressive thickness and fibrosis. The thickened muscle may cause midcavity obstruction which in turn promotes hypertrophy of the muscle bundle. The RV is effectively divided into 2 compartments. A high pressure inlet chamber and a low pressure thin walled outlet chamber
  • Aortic regurgitation (AR) : both perimembranous and supracristal VSDs can be associated with AR because of the proximity of the VSD with the aortic valve

Complication of moderate sized shunts

  • moderate PAH
  • mild dilatation of LA and LV

Complication of large sized shunts

  • heart failure
  • PAH

Treatment/Management

  • 85 to 90% of small isolated VSDs close spontaneously during the 1st year of life
  • small, asymptomatic VSDs without PAH have an excellent prognosis without intervention
  • Require endocarditis prophylaxis in patients with VSD repair or who have Eisenmenger’s syndrome
  • VSD closure : medium to large defects with significant haemodynamic compromise or if there is progressive aortic insufficiency or after an episode of bacterial endocarditis.

References

  1. Stat pearls Ventricular Septal Defect Wael Dakkak; Tony I. Oliver    https://www.ncbi.nlm.nih.gov/books/NBK470330/
  2. https://pedecho.org/library/fetal/Fet-VSD  Paediatric echocardiography : VSD
  3. Med J Armed Forces India. 2003 Jul; 59(3): 228–233. Published online 2011 Jul 21. doi: 10.1016/S0377-1237(03)80014-X
    Congestive Heart Failure in Infants and Children Mukti Sharma,* MNG Nair,+ SK Jatana,# and BN Shahi, PVSM, AVSM, VSM, PHS*
  4. The Practice of Clinical Echocardiography; Catherine Otto 5th edition

 

 

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