Ventricular septal defect

Ventricular septal defect


This is a defect in the ventricular septum. The defect can occur in the outlet, perimembranous, inlet or trabecular septum. It can vary in size or occur in more than one site in the same heart. It is one of the most common forms of congenital heart disease although it is seen much less commonly in the fetus than in postnatal life. A VSD is a common component of more complex forms of congenital heart disease, when the associated lesion will usually dominate the mode and timing of presentation. In addition, the presence of a large VSD can alter the prognosis in, for example, coarctation of the aorta. An outlet VSD is the characteristic VSD of the tetralogy of Fallot or a common arterial trunk; an inlet VSD is part of an atrioventricular septal defect. Although an inlet VSD usually occurs as part of a canal defect, it can be isolated. Inlet and outlet VSDs rarely close spontaneously, whereas perimembranous and trabecular defects commonly do. If the VSD is isolated and small, the child will present with an asymptomatic murmur. It has a high chance of closing spontaneously in the first years of life. If it is large (greater than half the aortic root size), the neonate will present with evidence of cardiac failure or failure to thrive. Most defects can be managed medically although intractable cardiac failure or pulmonary hypertension are reasons for surgical intervention in the first year of life. .


A defect in the outlet or perimembranous ventricular septum will be detected in the subaortic position in the long axis view of the left ventricle. A defect in the inlet septum will be seen in the four chamber views of the fetal heart and will cause loss of differential insertion of the atrioventricular valves. A trabecular defect has muscular edges and can be found in any part of the muscular septum. It usually will be detected in a four chamber view. Defects will usually have sharp edges to distinguish them from ‘drop-out’ commonly seen in the ventricular septum near the crux of the heart where the septum is very thin. Muscular VSDs best demonstrate this feature. A VSD in any site will only be seen in the early fetus if it is large, although small defects may be seen with good image quality in the later weeks of pregnancy. Bidirectional shunting will be seen across the defect when it is imaged with the beam perpendicular to the septum.

Differential Diagnosis

It can be very difficult to distinguish a true VSD from drop-out in any part of the septum particularly in the early fetus or if image quality is poor. To confirm a defect, colour flow must be seen crossing it when the ultrasound beam is perpendicular to the defect. ‘Smearing’ of colour across the ventricular septum is common in a normal heart when the beam is parallel to the septum and does not imply a true VSD.

Sonographic Features

Loss of septal continuity in any portion of the septum.

Defect delineated by sharp edges or ‘bright spots’ on echo.

Bidirectional shunting across the defect when beam perpendicular.

Associated Syndromes

  • 13q-
  • 18q-
  • 4p-
  • 5p- (Cri-du-chat)
  • 9p-
  • Aase
  • Diabetes
  • DiGeorge Sequence
  • Fetal Alcohol
  • Fetal Valproate Effects
  • Holt Oram
  • Noonan
  • Partial Trisomy 22
  • PKU
  • Retinoic Acid Retinopathy
  • Rubella
  • Rubinstein Taybi Syndrome
  • Shprintzen (Velo-Cardio Facial)
  • Thalidomide
  • Triploidy and Diploid/Triploid Mixoploidy
  • Trisomy 13
  • Trisomy 18
  • Trisomy 21
  • Trisomy 8 (mosaic)
  • Trisomy 9 (mosaic)
  • VACTERL Association
  • VATER Association
  • Williams


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