The document provides information about electrocardiography (ECG), including how an ECG works, the parts of an ECG recording, how to position a patient, standardization of readings, the 12 standard ECG leads and additional leads, artifacts that can appear on readings, abnormalities in cardiac rhythm including extrasystoles, tachycardias and fibrillations, and bibliographic references. It describes the device used, details of the recording paper, how leads are obtained and interpreted, and classifications of different cardiac arrhythmias and their characteristics on ECG readings.

1. UNIVERSIDAD TECNICA DE MACHALA
ACADEMIC UNIT OF CHEMICAL
SCIENCES AND HEALTH
MEDICINE SCHOOL
ENGLISH
ELECTROCARDIOGRAM
STUDENTS
William Cruz
Kevin Herrera
TEACHER:
Mgs. Barreto Huilcapi Lina Maribel
CLASS:
EIGHTH SEMESTER ‘’A’’
Machala, El Oro
2018

2. ELECTROCARDIOGRAM
The device.- The electrocardiograph
is a galvanometer that transcribes the
electrical signal to a paper, contains
electrodes that connect the patient
through the connection cables,
derivation selector and an amplifier.
The electrodes are colored metal
plates that capture electrical currents
for recording, which causes
displacements that graph waves on a
paper that advances at a speed of 25 mm per second.
THE REGISTRATION PAPER
It is millimeter grid. Formed by large squares separated by thick lines, which in
turn contain small squares of 1 mm on each side. Horizontally, time is measured:
a small square equals 0.04 sec .; a large square is equal to 0.2 sec; five large
squares equals 1 sec. (0.20 x 5).

3. Vertical is measured voltage or amplitude. A small square equals 0.1 mV and a
large square 0.5 mV; a wave of 1 mV is seen in two large frames (10mm).
THE PATIENT
Must be in dorsal decubitus on a flat, relaxed to avoid deflections by muscle
tremor and without moving avoiding sighs, the place should be sheltered to avoid
chills.
STANDARDIZATION
Set the paper speed that is 25 mm / sec. and the deflection voltage is 1 mV. When
it is exceeded, it is calibrated at 50.75º 100 mm per second.
ELECTROCARDIOGRAPHIC DERIVATIONS
Derivations: These are the points where the electrodes are placed. The electrical
potentials are picked up by two electrodes, one connected to the positive pole, the
other to the negative pole of the electrocardiograph. The derivations that are
usually used are twelve:
 Three bipolar derivations of limbs, called DI, DII and DIII.
 Three unipolar derivations of members: aVR, aVL and aVF.
 Six precordial leads: V1, V2, V3, V4, V5, V6.
The bipolar or standard derivations were devised by Einthoven; they are obtained
with the following arrangement of the electrodes:
DI: left arm (+) and right arm (-)
DII: left leg (+) and right arm (-)
DIII: left leg (+) and left arm (-)

4. The electrodes are placed on the right and left wrist and on the ankles. The
electrode on the right ankle is indifferent.
The lines that represent these three derivations forming the triangle of Einthowen.
 Law of Einthowen. At any time, the sum algebra of the deflections in the
DI and DIII leads is the same as that seen in the DII.
The multipolar leads of the limbs are obtained by connecting to the positive pole
of the electrode electrode of the member to be scanned and the negative pole is
connected to the Goldberg terminal (CTG). This terminal consists of connecting
the other two leads of resistance with resistances. members. Example: aVR =
positive right arm and negative CTG.
In the unipolar derivations of the members the letter "a" is prefixed because the
amplitude of the deflections has been increased by 50%; the letter "V" is used by
vector, the "R" by right (right), the "L" by left (left) and the "F" by foot (foot).
The precordial leads explore the heart in a horizontal plane, in contrast to the
previous leads that explore it only in the frontal plane. They are achieved by
applying a positive electrode in different points of the precordial region and the
negative electrode is connected to the central terminal of Wilson. This plant is
formed by joining the three members by means of resistances, so that their
combined potential can be considered as zero. The points where the positive
electrodes are placed are:

5.  V1: 4th intercostal space at
the right edge of the
sternum.
 V2: 4th intercostal space at
the left edge of the sternum.
 V3: intermediate point
between V2 and V4.
 V4: 5th left intercostal
space, midclavicular line.
 V5: Anterior axillary line,
at the same height as V4
 V6: Average axillary line, at
the same level as V4
ADDITIONAL DERIVATIONS
Subsequent derivations. The leads V7, V8 and V9 explore the heart in more
lateral and posterior areas, in case of infarction.
Right derivations. In cases of dextrocardia and right ventricular infarction, the
electrodes are placed on the right anterior chest wall, in points similar to those on
the left side, called V3R, V4R, etc., until the thoracic circle is formed.
Esophageal bypass The scanning electrode, placed at the end of a probe
swallowed by the patient, explains the posterior aspect of the left atrium and
ventricle.
Intraventricular shunt: the electrode located at the end of a catheter is
introduced intravenously into the right cavities.
Artifacts in the layout
They are disturbances of the electrocardiographic record originated by
circumstances outside the heart, which affects the morphology of a part or the
whole of the tracing and hinder its correct interpretation. The main ones are:
a) Inestability of the isoelectric line: oblique displacement of the baseline;
they are due to defective contacts of the electrodes or also to respiratory
movements.
b) Muscular tremor. Small oscillations irregularities of variable frequency.
They are due to involuntary muscle movements or muscle tension.
c) Alternating current: irregular waves in saw teeth; they originate by
interference of some electrical device.
d) Other less frequent artifacts can be caused by incorrect placement of the
electrodes, poor connections between wires and electrodes, and existence

6. of an artificial pacemaker, spikes before the QRS) and defects of the
inscription system.
ALTERATIONS OF THE CARDIAC RHYTHM
 Definition: irregularity is denominated arrhythmia in the formation and
conduction of the electrical stimulus, although the suitable term to be used
would be dysrhythmia.
 Analysis of an arrhythmia: To perform a good study of an arrhythmia, a
long stroke is required, using the leads in which the P wave is best seen
(usually DII and VI).
 Sinus rhythm: Sinus rhythm is characterized by a cup between 60 and
100 beats per minute. Each QRS complex must last between 80 and 100
ms and is preceded by a P wave and each P wave must be followed by a
QRS.
ALTERATIONS OF SINUS RHYTHM:
 Sinus arrhythmia.- The heart rate is irregular, increases and decreases
periodically, therefore the duration of the R-R spaces is variable.
It is the respiratory arrhythmia that usually consists in the acceleration of
the heart at the moment of inspiration, and a delay in expiration.
 Sinus tachycardia - the heart rate is higher than 100 beats per minute,
there is a shortening of the diastole, the P wave approaches and even
intervenes the T wave, it is also accompanied by shortening of the QT and
PR spaces and a vertical drop negative ST.

7.  Sinus Bradycardia.- The heart rate is below 60 beats per minute, it
consists essentially of a lengthening of diastole and is accompanied by a
slight lengthening of PR and QT.
ALTERATIONS IN PULSE FORMATION
In the normal heart, depolarization is initiated in the NSA, which is the
physiological pacemaker of the heart, spontaneously activating, with a frequency
of 60 to 80 times per minute. Under pathological conditions, depolarization starts
outside the so-called NSA, ectopic focus. which causes additional contractions in
the myocardium which are called extrasystole, these are the most frequent type of
cardiac arrhythmia, and can be classified into four fundamental aspects.
1. Its topography: headphones, nodes, ventricular.
2. Its frequency: isolated, bigeminated, trigeminated.
3. Its focus of origin: monofocal, polyfocal, polytropic.
4. The phase of the cardiac cycle in which it appears:
 Extrasystole auricular: the abnormal stimulus is born from a focus to
ectopic located in any part of the atrium, the extrasystole is characterized
by:

8. a) The extra systolic P wave, which has a different morphology from
the P wave of sinus origin, can sometimes be negative.
b) The PR segment of the extrasystole may be shortened.
 Paroxysmal tachycardia: It consists of a series of extrasystoles, with a
frequency greater than 100 per minute, these tachyarrhythmias usually
start and end suddenly.
 Atrial tachycardia. - It is originated by an ectopic auricular focus that has
constituted in the pacemaker of the heart and that generates impulses to
frequencies that vary between 180 and 240 per minute, the
electrocardiogram of the atrial tachycardia has the following
characteristics:
a) Heart rate from 180 to 240 per minute.
b) Normal P waves
c) Normal QRS complex, sometimes slightly enlarged

9. d) Regular RR interval.
 Auricular flutter: These arrhythmias are always initiated with an atrial
extrasystole and the mechanism that allows it is the circular movement, the
front of the wave, born with the extra systolic heartbeat, can travel through
the inter nodal bundles of the atria, describing a circle, to return to the
place where he was born and restart the cycle, the eCG has the following
characteristics:
a) Regular waves in the form of "sawtooth".
b) Normal QRS complex.
c) Ventricular frequency between 110 and 150 per minute.
 Atrial fibrillation: It is due to weak, fast and disordered electrical
discharges of many ectopic centers of the atria, with a frequency of 400 to
600 per minute, the ECG presents the following characteristics.
a) The P wave is replaced by a large number of irregular F waves,
often from 400 to 600 per minute.

10. b) The ventricular rate is sometimes greater than 100 or less than
60 per minute
c) QRS complexes are usually abnormal.
VENTRICULAR arrhythmias:
 Ventricular extrasystoles. The extra-systolic stimulus can originate in
one of the ventricles, although sometimes it is born from the bundle of His
or in any of the distal active tissues of the AV node, spreading throughout
the myocardium, through the contractile myocardium, its Morphological
characteristics are:
a) Absence of initial P wave.
b) Wide QRS complex
c) Wave T very high and generally opposite to the QRS with QT
elongation.
 Bigeminism .- to each normal systole, followed by an extrasystole.
 Trigeminism .- for every two normal systoles appears an extrasystole.
 Ventricular tachycardia shows a fast ventricular rate of 140 to 250 /
min. Rhythm slightly regular. Wide, flattened QRS complexes of
premature ventricular beats. The ST segments and the T waves are
indistinguishable. There is a frequency of the P wave independently
slower, although the P waves can be hidden.

11.  Ventricular fibrillation.- irregular rhythm. There are no defined
complexes. It may end in asystole as a final event. The layout is chaotic
with an absolutely irregular frequency, with complexes of form and
amplitude that change incessantly due to potential variations.
BIBLIOGRAPHIC REFERENCE
 "Record of the electrocardiogram" Segarra Edgar, Practices of
electrocardiography, Cuenca, pag. 14-23
 Segarra Edgar, Chapter 7, Alterations of the rhythm in: "Segarra, Edgar.
Electrocardiography practices. Edition 2016. N ° pag. 79 - 92