Introduction: the stethoscope

You will almost certainly be familiar with the stethoscope from visits to your general practitioner. An easy to use, non-invasive and inexpensive piece of equipment, it is one of the most common tools in doctors’ practices that is used to examine the respiratory and cardiovascular system (eg, the lung and heart).

Cardiac auscultation

Cardiac auscultation is often the first examination at which signs suggesting an underlying congenital heart defect are detected. By applying the stethoscope to the front and back of the upper part of the body, the physician is able to listen to the heart sounds.

Sounds of a healthy heart

Every heart produces characteristic rhythmic sounds: each beat of a healthy heart consists of two sounds that are often described as a ‘lub’ (first sound) and a ‘dub’ (second sound). These sounds are caused by the closing of the valves and the blood flowing through the heart.

Insignificant heart murmurs

Sometimes, further sounds called heart murmurs can be heard in addition to the normal sounds of the heart. However, detection of heart murmurs is not necessarily a bad sign, since innocent heart murmurs that are insignificant (benign) exist. These can be caused by the position of the child during the examination or its heart rate, for example. About 50% of all newborn babies and young children are estimated to have a heart murmur, but most disappear over time.

Significant heart murmurs

However, a heart murmur might also be caused by abnormal blood flow that can be the result of some congenital heart malformations. For example, the blood flow through a valve might be restricted (stenosis) or a valve might not close properly (insufficiency), which can lead to turbulences or blood flowing along the wrong paths.

Even if a heart murmur is produced because of an underlying heart defect, it is not automatically accompanied by other symptoms. However, some symptoms do suggest its presence, such as chest pain, rhythm disorders, breathlessness, fatigue or, in severe cases, cyanosis. Not every congenital heart defect leads to abnormal sounds that are audible with a stethoscope. Surprisingly, the most complex cases often have no abnormal sounds at all.

Further tests to confirm the diagnosis

Every patient with a heart murmur needs further tests to confirm its significance. Even though experienced physicians (eg, paediatric cardiologists) might be able to distinguish between innocent and significant heart murmurs and even make suggestions as to the type and location of the underlying defect, additional tests are essential to make a firm diagnosis and look at the heart and its surroundings in more detail. These additional tests will probably include an electrocardiogram (ECG) and echocardiography.

Author(s): Eva Niggemeyer
Reviewed by: Dr. Petra Böttler
Last updated: 2008-09-23