Webster's New World Medical Dictionary

ventricle, lateral
See 
lateral ventricle.
ventricle, left
The chamber of the heart that
receives blood from the left atrium and pumps it out
under high pressure to the body via the aorta. See
also 
heart ventricle.
ventricle, right
The chamber of the heart that
receives blood from the right atrium and pumps it
under low pressure into the lungs via the pulmonary
artery. See also 
heart ventricle.
ventricle, third
See 
third ventricle.
ventricular arrhythmia
An abnormal, rapid
heart rhythm (arrhythmia) that originates in the
lower chambers of the heart (ventricles).
Ventricular arrhythmias include ventricular tachy-
cardia and ventricular fibrillation. Both are life-
threatening arrhythmias that are commonly
associated with heart attacks and scarring of the
heart muscle from previous heart attacks.
ventricular fibrillation
See 
fibrillation, ven-
tricular.
ventricular septal defect
A hole in the wall
(septum) between the lower chambers of the heart
(ventricles). Abbreviated VSD. VSDs are the most
common birth defect that involves malformation of
the heart. At least 1 baby in every 500 is born with a
VSD. A VSD shunts blood from the left ventricle,
where it is under relatively high pressure, into the
right ventricle, which has to do extra work to han-
dle the additional blood. The right ventricle may
have trouble keeping up with the load, enlarge, and
fail. The lungs also receive too much blood under
too great pressure. The small arteries (arterioles)
in the lungs thicken up in response, and permanent
vascular damage can be done to the lungs. VSDs that
are small permit only minimal shunting of blood, so
the pressure in the right ventricle remains normal
and the heart and lungs function normally. Surgical
repair is not recommended for small VSDs since
many close on their own over time. With a large
VSD there is a significant shunt into the right 
ventricle, excessive blood flow into the lungs, and
elevated pressure in the arteries to the lungs (pul-
monary hypertension). Surgery should be done to
close a large VSD. The prognosis for patients with
VSD is generally excellent.