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13. General Information About the Heart and ECG Measurements
The heart is a muscular pump controlled by electrical impulses gener ated by the
body. It is divided into two by the septa and each side has two chambers – an
atrium and a ventricle – linked by a one-way valve. The left atrium and ventric le
control oxygenated blood, and the right atrium and ventricle de-oxygenated
(“used”) blood.
The electrical impulse that causes the heart to beat spreads across the atr ia,
causing the left and right atrium to contract and pump blood into the left and right
ventricles respectively. The two ventricles then contract and pump blood out of the
heart. The heart muscle then relaxes, or re-polarises, allowing blood to fill up the
heart again.
An ECG monitor is able to measure the electrical impulse as it passes across and
through the heart, causing the heart to beat. An ECG does not measure the
movement of your heartbeat, but rather the electrical activity that causes the heart
to beat. The measurements recorded by an ECG monitor, when combined with a
medical examination, can help your doctor monitor your heart conditio n.
Conditions such as arrhythmia and Ischemia can only be diagnosed by a d octor
through a special examination.
Left atrium
Left ventricle
Right atrium
Right ventricle Septa
HCG-801-E.book Page 54 Tuesday, December 13, 2011 5:35 PM