Ventricular Septal Defect (VSD)

A ventricular septal defect (VSD) is a defect in the ventricular septum, the wall dividing the left and right ventricles of the heart.The ventricular septum consists of an inferior muscular and superior membranous portion and is extensively innervated with conducting cardiomyocytes.The membranous portion, which is close to the atrioventricular node, is most commonly affected in adults and older children in the United States. It is also the type that will most commonly require surgical intervention, comprising over 80% of cases.
Membranous ventricular septal defects are more common than muscular ventricular septal defects, and are the most common congenital cardiac anomaly.

Locations

Membranous septum 1. Supracristal and Infracristal

Muscular septum, may be multiple

Symptoms of Ventricular Septal Defect (VSD)

Often asymptomatic

Frequent respiratory infections

Congestive heart failure (Large VSD)

Diagnosis of  Ventricular Septal Defect (VSD)

Signs

A Ventricular Septal Defect can be detected by cardiac auscultation. Classically, a VSD causes a pathognomonic holo- or pansystolic murmur. Auscultation is generally considered sufficient for detecting a significant VSD. The murmur depends on the abnormal flow of blood from the left ventricle, through the VSD, to the right ventricle. If there is not much difference in pressure between the left and right ventricles, then the flow of blood through the VSD will not be very great and the VSD may be silent. This situation occurs a) in the fetus (when the right and left ventricular pressures are essentially equal), b) for a short time after birth (before the right ventricular pressure has decreased), and c) as a late complication of unrepaired VSD.

Hyperdynamic laterally displaced apexbeat systolic thrill left sternal border

Loud harsh Pansystolic murmur in mid left sternal boarder. Small VSD produces louder and higher pitched short systolic murmur.

Medium intensity systolic murmer in second inetrcostal space in supracristal VSD.

Short mid diastolic mitral flow murmur in large Left-Right shunts (>2:1)

Aortic incompetence murmur in superacristal VSD with prolapsed aortic leaflet.

Continuous murmur in Left Ventricle-Right Atrial shunt in high membranous VSD.

X-Ray findings

Pulmonary vascularity.Left Atrium and Left Ventricular enlargement in moderate shunt; Right Ventricular enlargement in addition in large shunt.

ECG findings

Normal in small shunt.Biventricular enlargement in large shunt

Echo findings

Confirmation of cardiac auscultation can be obtained by non-invasive cardiac ultrasound (echocardiography).Visualisation of the location of defect.Negative contrast in saline contrast study.Doppler detection of gradient.To more accurately measure ventricular pressures, cardiac catheterization, can be performed.

Treatment in Ventricular Septal Defect (VSD)

Small shunts

Endocarditis prophylaxis.

Spontaneous closure common.

Large shunts

Open heart surgery and closure by Dacron patch or Placement of button / umbrella prosthesis via catheter.

Mechanisms of VSD closure

Spontaneous, in small intramuscular VSD.Aneruysm formation from membranous septum.Prolapse of aoretic leafleft in supracristal defect.Contraction of septal muscle around the defect.Transcatheter closure figure given below.

Differentiation of VSD with Pulmonary Stenosis from Falot Tetralogy

In VSD with Pulmonary Stenosis, ejection clock of Pulmonary Stenosis is prominent (absent in Fallot tetralogy).

M mode Echo shows overriding of aorta from discontinutity of IV septum and anterior aortic wall in Fallot tetrology Echo Doppler shows the over riding and infundibular gradient.