Ventricular septal defect

A ventricular septal defect is an opening in the wall between the heart’s ventricles. It can allow blood to pass from the higher-pressure left ventricle into the right ventricle.

Left-to-right shunt: Blood flows from the left side of the heart to the right side through an abnormal connection. Pressure differences usually drive blood through a VSD from the left ventricle into the right.
Congenital heart defect: A structural abnormality of the heart or its major vessels that is present at birth. VSD is one of the most common congenital heart defects.
Echocardiography: Ultrasound imaging that shows heart structure, motion, and blood flow. It locates a VSD and estimates its size and hemodynamic effects.
Perimembranous ventricular septal defect: A VSD located near the membranous portion of the ventricular septum and the heart’s valves. This is a common form, with location relevant to valve and conduction risks.
Pulmonary overcirculation: Excess blood flow through the lungs, which can strain pulmonary vessels and the right side of the heart. A large VSD sends extra blood into the pulmonary circulation.
Fetal circulation: The pattern of blood flow through the fetus, in which the placenta supplies oxygen and fetal pathways bypass the lungs. Ventricular septal formation occurs while fetal circulation is developing.
Cardiac catheterization: A procedure that measures heart and vessel pressures and can assess blood flow using catheters. It can clarify pulmonary pressures when noninvasive tests are insufficient.
Muscular ventricular septal defect: A VSD surrounded by muscular tissue within the ventricular septum. Small muscular defects often close spontaneously during childhood.
Eisenmenger syndrome: Advanced pulmonary vascular disease that reverses a long-standing left-to-right shunt, causing blood to flow right to left. Untreated large VSDs can raise lung pressure until the shunt reverses.
Cardiac development: The embryonic processes that form the heart’s chambers, valves, septa, and major vessels. Disruption of septal development can leave a ventricular opening.

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