Biomedical Engineering Reference
In-Depth Information
Chapter 1
Introduction
1.1 Introduction
Even more than a century after its invention, electrocardiogram (ECG) still
remains the primary choice of the physicians for preliminary level investigation of
patients against chest pains and a helpful clue to the generalized disorders that
affect the rest of the body too. It is a simple non-invasive technique to explore the
cardiac functions of a patient. This chapter is aimed to discuss the basics of ECG,
its genesis, and lead systems. This is followed by a discussion on current health-
care scenario and context of introducing telehealth facility and its significance in
the developing nations.
1.2 Heart and Cardiovascular System
Human heart is a four-chambered, hollow, and flexible organ that collects impure
blood from the other organs, purifies it, and then circulates oxygenated blood to the
whole body. It is placed in the thoracic chamber, anterior to the vertebral column
and posterior to the sternum, slightly offset to the left. Depending on the age, it
weights between 250 and 350 g. Human heart consists of two pairs of atria and
ventricles, longitudinally connected. The heart along with the network of veins
(carry deoxygenated blood) and arteries (carry oxygenated blood) forms the car-
diovascular system to supply blood to the whole body. The word cardiac is derived
from Greek word 'kardia,' meaning 'related to the heart.' Considering its
importance to support life, heart is considered as one of the three most important
body organs, along with kidney and central nervous system. The heart is cushioned
in a two-layered sac called pericardium. The outer layer, named fibrous pericar-
dium, protects the heart against mechanical damage and prevents its overfilling
with blood. The outer wall of the heart consists of three layers, viz. epicardium,
myocardium, and endocardium. The first one forms the inner layer of pericardium,
and the last one forms the heart chambers. Between the heart chambers and outlet
