1. LOVELY PROFESSIONAL UNIVERSITY
TERM PAPER
On
BIOMEDICAL INSTRUMENTATION AND PROCESSING
Submitted To: Submitted By:
Mr. Ansul Mahajan Manish Kumar
Assist. Prof of LPU Reg.No-10906909
Roll No-B52

2. ACKNOWLEDGEMENT
I’m Manish Kumar, student of B.Tech(ECE) 7th term expressing my deep
gratitude to my BIOMEDIC INSTRUMENTATION AND PROCESSING
teacher “Mr. ANSUL MAHAJAN” I am very much thankful to him. I benefited
a lot discussing with him. I am also thankful to my parents who encouraged me
and provided such a motivation, so I became able to perform this. I am also
thankful to all my friends and those who helped me directly or indirectly in
completion of my term Paper.
MANISH KUMAR

3. ABSTRACT
The objective of artifacts electrocardiographic (ECG) signals are the observation and
assessment of the heart's electrical activity. Electronic advancements have produced
instrumentation with the potential of providing accurate information and reliable heart rate
alarms. Computerized monitors enhance patient assessment by allowing uninterrupted
electronic observation of heart rate and ectopic activity with comprehensive automatic
reporting mechanisms. Despite these improvements in instrumentation, monitoring systems
continue to be plagued by problems related to poor signals. Wandering baselines, small
complexes, fuzzy tracings, and frequent electrode replacement make patient assessment
difficult and induce false heart rate alarms. Improvement in electrode preparation techniques
and a better understanding of the sources of artifact can enhance equipment performance,
resulting in improved patient assessment, more effective utilization of nursing time, and
reduced operating costs. This article discusses the physiologic and non-physiologic sources of
ECG monitoring artifact and presents a method of electrode site preparation to reduce
artifact.

4. CONTENTS
1. INTRODUCTION.
2. VARIOUS TYPE OF ARTIFACTS.
• INTERNAL ARTIFACTS
• EXTERNAL ARTIFACTS
3. DIFFRENT METHOD TO REMOVE OF ARTIFACTS.
4. CONCLUSION
5. REFRENCES

5. INTRODUCATION
The electrical activity of the heart is sensed by monitoring electrodes placed on the skin
surface. The electrical signal is very small (normally 0.0001 to 0.003 volt). These signals are
within the frequency range of 0.05 to 100 Hertz (Hz.) or cycles per second. Unfortunately,
other artifactual signals of similar frequency and often larger amplitude reach the skin surface
and mix with the ECG signals. In electrocardiography, an ECG artifact is used to indicate
something that is not heart-made. These include (but are not limited to) electrical interference
by outside sources, electrical noise from elsewhere in the body, poor contact, and machine
malfunction. Artifacts are extremely common, and knowledge of them is necessary to
prevent misinterpretation of a heart's rhythm.
SOURCES OF ARTIFACTS IN ECG SIGNAL
Artifactual signals arise from several internal and external sources.
 Internal Arifacts:
(1) Signals from muscles and
(2) Signals produced in the epidermis
 Signals from muscles:
All muscle activity produces electrical signals. Signals from muscles other than the heart are
called EMG signals and appear on the monitor as narrow, rapid spikes associated with muscle
movement. These signals are sufficiently dissimilar to the ECG signals that they can be
electronically reduced or "filtered" from the trace. This filtering is readily observed by
reduction in the size of EMG signals as the monitor is switched from the diagnostic mode to
the monitor mode.
Fig1 shows that when muscle activity produces electrical signal

6.  Signals produced in the epidermis:
The skin is a source of electrical signals which produce motion artifact. Studies have
revealed that a voltage of several milli volts can be generated by stretching the epidermis,
the outer layer of the skin. This stretching is the primary source of movement-related
artifact. This type of artifact is visible as large baseline shifts occurring when the patient
changes positions in bed, eats or ambulates. Epidermal artifact is more troublesome than
other types of artifact because:
(A) it is difficult to filter electronically and
(B) ) its amplitude is often larger than the ECG signal.
Fig 2. Shows that when skin a sources electrical signal
 External Artifacts:
(1) 60 Hz. AC interference
(2) Offset signals produced by the electrode itself
(3) Signals produced by the interaction of body fluids and the electrode gel
(4) Lead wire and patient cable problems.
(5) Reversed leads.
 60 Hz. AC interference:
This type of artifact, also called 60 Hz. Interference, produces a wide, fuzzy baseline. It is
related to poor electrode contact associated with poor skin preparation techniques, dried
electrode gel, or defective patient cables or lead wires.

7. The source of 60 Hz. pickup is the 60 Hz. current which supplies power to the electrical wall
outlets. The 60 Hz. energy "radiates" from the electrical wiring in the patient's room and is
received in the lead wires and by the patient. The source of radiation cannot be eliminated,
but modern monitors can reduce 60 Hz. pickup by filtering and by an electronic technique
called common mode rejection. This technique requires good skin contact by all electrodes.
One or more electrodes with poor contact will result in the wide fuzzy baseline.
Alternating current (AC) describes the type of electricity that we get from the wall. In the
United States, the 60 hertz. Many places in Europe use 50 Hz AC electricity. When an ECG
machine is poorly grounded or not equipped to filter out this interference, you can get a thick
looking ECG line.fig 1.
Fig 3 shows that when AC power to the electrical wall outlets.
 2) Offset signals produced by the electrode itself:
An offset potential is a voltage that is stored by the electrode. This stored voltage will add to
the ECG signal and interfere with it. The offset potential causes the disappearance of the
ECG after defibrillation. The amount of offset potential and the length of time required for it
to dissipate are determined by the materials used for the electrode and the gel. Certain
combinations of metals and gels generate large voltages (up to 200 millivolts) with the ability
to hold this voltage for long periods of time. Electrode materials such as silver-silver chloride
do not allow significant build-up of offset potential, whereas stainless steel electrodes have
poor offset characteristics. Most electrodes used for ECG monitoring today are made of
silver-silver chloride. With the common use of the silver-silver chloride electrode, offset
potentials are no longer considered to be a significant problem.
Fig 4. Shows that when offset potential voltage that is stored by the electrode

8.  Signals produced by the interaction of body fluids and electrode gel:
Movement of the electrode gel under the electrode was thought to be the primary cause of
motion artifact. The electrode gel does, however, significantly affect the transmission of
signals from the skin to the electrode. The lack of sufficient electrode gel, frequently due to
evaporation caused by improper storage, results in 60 Hz. pickup and extremely unstable
traces. This type of artifact is easily identified by very high electrode impedances
Electrode impedances
In order for ECG signals to pass from the body to the electrode, an electrically conductive
path between the skin and electrode must be established. The conductive ability of this path is
referred to as electrode impedance or contact impedance. Electrode impedance is measured in
ohms. High impedance decreases the conduction of the ECG signal. Low impedances
improve this conduction. The major factors affecting electrode impedance are:
(a) The quantity and quality of gel between the electrode and the patient and
(b) The degree to which the outer layer of the epidermis has been bridged by the conductive
gel.
Proper site preparation will produce contact impedances of 10,000 ohms or less in 90% of
patients.9 Less than 5,000 ohms is a good target value. Improper site preparation will usually
produce contact impedances as high as 1M to 2M ohms.
Fig 5. Shows that when movement of electrode.
 Lead wire and patient cable problems:
Breaks in the wires and connections between the electrode and the monitor will always be a
source of monitoring problems. Poor contact at any snap connection, loose pins at the cable
end of the lead wire, and breaks in the conductors of the lead wire or patient cable can cause
intermittent loss of the ECG tracing, 60 Hz. Pickup.

9.  Reversed leads:
Electrode/lead placement is very important. If one were to accidentally confuse the red and
white lead cables i.e. place the white one where the red one should go, vice versa, he might
get an ECG that looks like figure 6. In this ECG, we can make out a normal sinus rhythm
with all of the waves upside-down. When this happens, you are essentially viewing the
rhythm in a completely different lead. One must also make sure that the lead wires are
actually plugged into the machine. If your talkative patient shows a systole, you should
suspect this. Many machines are smart in that they can sense common errors of this nature,
but many such errors aren't always readily apparent.
Fig 6. Shows that when elerode are wrong placed.
ARTIFACTS REMOVAL IN ECG SIGNALS
The electrical activity of the heart is sensed by electrodes that are placed on the skin’s
surface. The heart’s electrical signal is very small (normally 0.0001 to 0.003 volt), and
unfortunately this can be combined with artifactual signals of similar frequency and often
larger amplitude.
Each patient’s ECG is unique. The patient’s size, skin type, age, and pathology, as well as
where the electrodes are placed, influences the results of the tracing. Poor signal quality can
cause noise or artifacts on the ECG, which in turn leads to inaccurate analysis of the ECG.
Now different Method to minimize the artifacts in ECG signal
 Perform good skin preparation
The build-up of skin oils and residues increases the resistance to the conduction of the
electrical signal.
 Check for AC interference

10. 50/60 Hz. interference looks like small regular peaks and produces a wide, fuzzy baseline. It
is traced to the 50/60 Hz. current which supplies power to the electrical wall outlets. The
50/60 Hz. energy radiates from the electrical wiring in
the patient’s room and can be picked up by the patient and/or the lead wires. This will result
in AC interference on the ECG tracing. There are several causes of AC interference:
• Electrical wires in the walls, ceiling or floor.
Suggestion: Move the examination table away from walls
 Check the electrodes
Check the electrode gel to make sure it is fresh and moist. The electrode gel greatly affects
the transmission of signals from the skin to the electrode. A dry electrode with inadequate
conducting gel will not work properly since it reduces the conduction of the ECG signal. In
most instances, electrode gel dry-out is simply a result of incorrect storage. Electrodes are
packaged in metal foil pouches to prevent gel evaporation. Use this point
• Use electrodes prior to their expiration date.
• Do not remove the electrodes from their pouch until they are ready to be used.
 Verify filter settings in the device
Finally, if the tracings are still showing artifact, make sure that the following filters are turned
on:
• Muscle filter
• AC filter
• Wandering baseline filter
 Make sure the patient is warm, relaxed and does not move or speak
It is important to make sure the patient is warm and relaxed during the test because we want
to reduce muscle tremors and movement as much as possible since they can impair the
quality of recordings.
Filtering methods
• High pass filtering (HPF)
• Adaptive filtering (AF)
• Kalman filtering(KF)

11. In signal processing, there are many instances in which an input signal to a
system contains extra unnecessary content or additional noise which can
degrade the quality of the desired portion. In such cases we may remove or
filter out the useless samples.
CONCLUSION
Artifact in ECG monitoring can be annoying, costly, and dangerous. An understanding of the
sources of artifact and care in the application of monitoring electrodes can significantly
reduce or even eliminate the problem. The filter robustness is crucial for ECG artifact
removal. Artifacts removal method now days very easy to design because there are no. Of
filter devices available in market so we reduce easily to remove artifacts.
REFRENCES:
http://www.general-devices.com/rx-ecg-artifact
http://www.welchallyn.com/documents/Cardiopulmonary/Electrocardiographs/ReduceArtifac
t_20080918_ECG.pdf
o BIOMEDICAL SIGNAL ANALYSIS: A CASE-STUDY APPROACH, Author
RANGARAJ M. RANGAYYAN , Edition 1st, Publisher Name-Wiley, Year-2009,chap-3.
o Tam, H.W. and Webster, J.G. Minimizing Electrode Motion Artifact by Skin Abrasion.
Institute of Electronic and Electrical Engineers (IEEE) Transactions on Biomedical
Engineering (BME), 24(2): 134-139, 1977
o Knight, BP; Pelosi, F; Michaud, GF; Strickberger, SA; Morady, F; Clinical
consequences of electrocardiographic artifact mimicking ventricular tachycardia. N
Engl J Med 1999; 341:1270–1274.