Cardiothoracic Surgery Patient Care – UT Cardiothoracic Surgery

The heart: The interior of the heart is composed of valves, chambers, and associated vessels.

In the human body, the heart is normally situated to the left of the
middle of the thorax, underneath the breastbone. The
heart is usually felt to be on the left side because the left heart
(left ventricle) is stronger (it pumps to all body parts).

The left lung
is smaller than the right lung because the heart occupies more of the
left hemithorax.

The heart is enclosed by a sac known as the pericardium
and is surrounded by the lungs. The pericardium is a double membrane
structure containing a serous fluid to reduce friction during heart
contractions. The mediastinum, a subdivision of the thoracic cavity, is
the name of the heart cavity.

The apex is the blunt point situated in an inferior (pointing down and
left) direction. A stethoscope can be placed directly over the apex so
that the beats can be counted. This physical location is between the
sixth and seventh rib, just to the left of the sternum.

In normal
adults, the mass of the heart is 250-350 g (9-12 oz), or about three
fourths the size of a clenched fist, but extremely diseased hearts can
be up to 1000 g (2 lb) in mass due to hypertrophy.

The heart consists of four
chambers, the two upper atria and the two lower
ventricles.

The function of the right side of the heart (see right heart) is to
collect deoxygenated blood, in the right atrium, from the body and pump
it, via the right ventricle, into the lungs (pulmonary circulation) so
that carbon dioxide can be dropped off and oxygen picked up (gas
exchange). This happens through a passive process called diffusion. The
left side (see left heart) collects oxygenated blood from the lungs into
the left atrium. From the left atrium the blood moves to the left
ventricle which pumps it out to the body. On both sides, the lower
ventricles are thicker and stronger than the upper atria. The muscle
wall surrounding the left ventricle is thicker than the wall surrounding
the right ventricle due to the higher force needed to pump the blood
through the systemic circulation.

Heart disease involves any disorder that affects the heart’s ability to
function normally. The most common cause of heart disease is narrowing
or blockage of the coronary arteries, which supply blood to the heart
itself. Some patients are born with abnormalities (congenital heart
disease).