Introduction to Cardiac congenital defects

Posted on November 26, 2010 - 8:36pm

Congenital cardiac disorders, with an incidence of 1/1000 newborns, belong to the most frequent birth defects. Chromosomal aberrations are frequently associated with heart abnormalities.

Before we go on, please review here the development of the heart:

Let's also review the pre and post birth circulations:

Please observe that before birth the IVC flows primarily to the left Atrium via the Foramen Ovale, while the blood returning via the SVC drains into the RV and from there the PA:

Before birth there is only mixed blood  in the circulation system.  The numbers provide the approximate O2 saturation:                               

Before birth there is only mixed blood in the circulation system. The numbers provide the approximate O2 saturation                                    

After birth O2 saturations and pressures.

After birth the two circulation systems are separated and now only blood that is saturated with O2 gets into the aorta.

Below is a list of the four most common cardiac defects. They make up more than half of all abnormalities:

You can observe the following:

In infants:

  • Cyanosis (due to a mixture of O2 saturated with O2 unsaturated blood)
  • Poor growth (the baby fails to gain weight)
  • Excessive sweating, mainly when drinking (a big effort for the child)
  • Shortness of breath
  • Poor nursing (the baby often falls asleep while nursing due to the large effort it must expend)

In older children:

  • Low exercise tolerance
  • Tendency for infections

You can subdivide congenital heart abnormalities according to location and hemodynamic effects. In the case of an incomplete separation of pulmonary and systemic circulations, a shuntis formed. With each cardiac contraction the blood flows from one circulation system into the other according to the different blood pressures in the two systems.

Cardiac abnormalities can thus be subdivided into the following groupings:

  1. Cardiac defects without a shunt
  2. Cardiac defects with a left-right shunt (normally without cyanosis)
  3. Cardiac defects with a right-left shunt (with cyanosis
  4. False connections of the great vessels

Besides auscultation, echocardiography is now the most frequently applied diagnostic method for clinical examinations. Cardiac catheterization examinations are indicated in complex cardiac abnormalities and before operations.