Ventricular Septal Defect

Definition: interventricular septal communication (IVS) defined by its location. The IVS can be divided into a muscular and membranous portion, hence perimembranous VSD (80%) or muscular VSD (inlet/trabecular/outlet = infundibular region).  It is the most common type of CHD.

Incidence: 1.7-53:1000 of all live births.

Prevalence: 20% as a single lesion, 50% as part of lesion in CHD.

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Physiology:

Depends on the size, PVR, RVP and LVP

• in neonates with increased PVR there is minimal shunting
• where there is a drop in PVR and and therefore less restrictive, there is a left to right shunt leading to volume load in the LA and LV.  This can lead to CCF and, if long standing, Eisenmenger syndrome

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Diagnosis:

• Clinical examination: auscultation – holosystolic murmur; cyanosis; and clubbing in Eisenmenger syndrome
• ECG: LVH
• CXR: increased pulmonary blood blow (in Eisenmenger there is reduced PBF)
• ECHO: for size, location, shunt, haemodynamic evaluation
• MRI: limited usefulness
• Cardiac catheterization: PVR, response to pulmonary vasodilators, Qp:Qs

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Preoperative management:

Treat CCF: CPAP/IPPV if required; digoxin; frusemide (1mg/kg up to QID); spironolactone (1mg/kg BD).

Aim for an afterload reduction:milrinone (0.25-0.5 mcg/kg/min) or captopril (0.1-2 mg/kg TDS).

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Preoperative preparation:

ECG, CXR, CUS, FBE, clotting, UEC, PRBC (4), FFP (2), platelets (2), cryoprecipitate (2). methylprednisolone 10mg/kg 12hrs and 6hrs pre surgery in neonates.

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Surgery:

Pulmonary artery banding for protection of pulmonary circulation in neonates with multiple VSDs and CCF

In children >3 months (Qp:Qs >1.5:1), surgical closure via transatrial approach, sometimes by right ventriculotomy, and rarely by left apical ventriculotomy. Catheter closure by amplatzer device. Heart-lung transplantation in Eisenmenger syndrome.

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Postoperative management:

• Inotropes: milrinone plus dopamine or adrenaline (plus noradrenaline). Aim for MAP >40 mmHg in neonates.
• Haemodynamics: age adjusted (in neonates: SBP >60 mmHg, MAP >40 mmHg, CVP 8-12 mmHg).
• Respiratory: normoxaemia, normocapnea.
• Fluid restriction: 1ml/kg/hr, early feeds.
• Continue preoperative diuretic therapy.
• Haemostasis.
• If catheter closure: aspirin 5mg/kg OD once feeds tolerated.

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Specific problems:

• Risk of pulmonary hypertension in older children and Qp:Qs >1.5:1.
• Arrhythmia: complete heart block, SVT, JET.

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Outcome:

Average ICU stay: 2 days.

Mortality: <1% in isolated VSD, but up 5-10% in multiple defects.

Residual shunts: 30% after surgical closure, majority close spontaneously.

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References:

[1] Br Heart J. 1980 Mar;43(3):332-43: Soto et al: Classification of ventricular septal defects

[2] Circulation. 2006 Nov 14;114(20):2190-7: Minette et al: Ventricular septal defects

[3] Cardiol Young. 2007 Jun;17(3):243-53: Butera et al: Percutaneous closure of ventricular septal defects

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