The document provides information about the structure and function of the heart and electrocardiography. It discusses how the heart is made up of chambers and valves that allow blood to circulate through the body. It describes how heart muscle cells generate electrical signals that cause the heart to contract in a rhythmic pattern. The conduction system allows electrical signals to spread efficiently and trigger coordinated contractions. An ECG records these electrical signals to evaluate cardiac rhythm and diagnose heart conditions.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
2. • The heart is a hollow muscular organ that
pumps blood around the body.
• With each beat, it pumps, at rest, about 70
millilitres of blood and considerably more
during exercise.
• Over a 70-year life span and at a rate of
around 70 beats per minute, the heart will
beat over 2.5 billion times.
DR POTNURU SRINIVASA SUDHAKAR 2
3. • The heart consists of four main chambers (left
and right atria, and left and right ventricles)
and four valves (aortic, mitral, pulmonary and
tricuspid).
• Venous blood returns to the right atrium via
the superior and inferior vena cavae, and
leaves the right ventricle for the lungs via the
pulmonary artery.
• Oxygenated blood from the lungs returns to
the left atrium via the four pulmonary veins,
and leaves the left ventricle via the aorta.
DR POTNURU SRINIVASA SUDHAKAR 3
5. • The heart is made up of highly specialized cardiac
muscle comprising myocardial cells (myocytes),
which differs markedly from skeletal muscle
because heart muscle:
1. Is under the control of the autonomic nervous
system.
2. Contracts in a repetitive and rhythmic manner.
3. Has a large number of mitochondria which make
the myocytes resistant to fatigue.
4. Cannot function adequately in anaerobic
(ischaemic) conditions.
DR POTNURU SRINIVASA SUDHAKAR 5
7. • Myocytes are essentially contractile but are
capable of generating and transmitting
electrical activity.
• Myocytes are interconnected by cytoplasmic
bridges or syncytia (A large cell-like structure
formed by the joining together of two or
more cells.), so once one myocyte cell
membrane is activated (depolarized), a wave
of depolarization spreads rapidly to adjacent
cells.
DR POTNURU SRINIVASA SUDHAKAR 7
8. Myocardial cells are capable of being:
1. Pacemaker cells:
• These are found primarily in the sinoatrial (SA)
node and produce a spontaneous electrical
discharge.
2. Conducting cells:
• These are found in: The atrioventricular (AV)
node.
• The bundle of His and bundle branches.
• The Purkinje fibers.
3. Contractile cells:
• These form the main cell type in the atria and
ventricles.
DR POTNURU SRINIVASA SUDHAKAR 8
10. • All myocytes are self-excitable with their own
intrinsic contractile rhythm.
• Cardiac cells in the SA node located high up in the
right atrium generate action potentials or
impulses at a rate of about 60–100 per minute, a
slightly faster rate than cells elsewhere such as
the AV node (typically 40–60 per minute) or the
ventricular conducting system (30–40 per
minute), so the SA node becomes the heart
pacemaker, dictating the rate and timing of action
potentials that trigger cardiac contraction, over
riding the potential of other cells to generate
impulses.
• However, should the SA node fail or an impulse
not reach the ventricles, cardiac contraction may
be initiated by these secondary sites (‘escape
rhythms’). DR POTNURU SRINIVASA SUDHAKAR 10
11. THE CARDIAC ACTION POTENTIAL
• The process of
triggering cardiac cells
into function is called
cardiac excitation–
contraction coupling.
• Cells remain in a
resting state until
activated by changes
in voltage due to the
complex movement of
sodium, potassium
and calcium across the
cell membrane ; these
are similar to changes
which occur in nerve
cells.
DR POTNURU SRINIVASA SUDHAKAR 11
12. • Phase 4:
• At rest, there is little
spontaneous
depolarization as the
Na+/K+/ATPase
pump maintains a
negative stable
resting membrane
potential of about
–90 mV.
DR POTNURU SRINIVASA SUDHAKAR 12
13. • so once one myocyte
cell membrane is
activated
(depolarized), a wave
of excitation spreads
rapidly to adjacent
cells; the SA node,
whose cells are
relatively permeable
to sodium resulting in
a less negative resting
potential of about –55
mV, is usually the
source of
spontaneous action
potentials
-55
mV
DR POTNURU SRINIVASA SUDHAKAR 13
14. • Phase 0:
• There is rapid
opening of sodium
channels with
movement of
sodium into the
cell, the resulting
electrochemical
gradient leading to
a positive resting
membrane
potential.
POSITIVE
DR POTNURU SRINIVASA SUDHAKAR 14
15. • Phase 1:
• When membrane
potential is at its
most positive, the
electrochemical
gradient causes
potassium outflow
and closure of
sodium channels.
POSITIVE
DR POTNURU SRINIVASA SUDHAKAR 15
16. • Phase 2:
• A plateau phase
follows, with
membrane potential
maintained by calcium
influx; membrane
potential falls towards
the resting state as
calcium channels
gradually become
inactive and
potassium channels
gradually open.
DR POTNURU SRINIVASA SUDHAKAR 16
17. • Phase 3:
• Potassium
channels fully
open, and the
cell becomes
repolarized.
DR POTNURU SRINIVASA SUDHAKAR 17
18. • Phase 4:
• Calcium, sodium
and potassium
are gradually
restored to
resting levels by
their respective
ATPase-
dependent
pumps.
NEGATIVE
DR POTNURU SRINIVASA SUDHAKAR 18
20. • Each normal
heartbeat begins with
the discharge
(‘depolarization’) of
the SA node.
• The impulse then
spreads from the SA
node to depolarize
the atria.
• After flowing through
the atria, the
electrical impulse
reaches the AV node,
low in the right
atrium.
DR POTNURU SRINIVASA SUDHAKAR 20
21. • Once the impulse has traversed the AV node,
it enters the bundle of His which then divides
into left and right bundle branches as it passes
into the interventricular septum.
• The right bundle branch conducts the wave of
depolarization to the right ventricle, whereas
the left bundle branch divides into anterior
and posterior fascicles that conduct the wave
to the left ventricle.
DR POTNURU SRINIVASA SUDHAKAR 21
23. • The conducting pathways end by dividing into
Purkinje fibres that distribute the wave of
depolarization rapidly throughout both
ventricles.
• Normal depolarization of the ventricles is
therefore usually very fast, occurring in less
than 0.12 s.
DR POTNURU SRINIVASA SUDHAKAR 23
25. The electrocardiogram (ECG) is essential for
• The identification of disorders of the cardiac
rhythm.
• Extremely useful for the diagnosis of
abnormalities of the heart (such as myocardial
infarction) and a helpful clue to the presence
of generalized disorders that affect the rest of
the body too (such as electrolyte
disturbances).
DR POTNURU SRINIVASA SUDHAKAR 25
26. WHAT DOES THE ECG ACTUALLY RECORD?
DR POTNURU SRINIVASA SUDHAKAR 26
28. • When the cardiac impulse passes through the
heart, electrical current also spreads from the
heart into the adjacent tissues surrounding
the heart.
• A small portion of the current spreads all the
way to the surface of the body.
DR POTNURU SRINIVASA SUDHAKAR 28
29. • If electrodes are placed on the skin on
opposite sides of the heart, electrical
potentials generated by the current can be
recorded; the recording is known as an
electrocardiogram.
DR POTNURU SRINIVASA SUDHAKAR 29
31. Characteristics of the Normal
Electrocardiogram
• The normal electrocardiogram
is composed of
• P wave,
• QRS complex, and
• T wave.
• The QRS complex is often, but
not always, three separate
waves:
• Q wave,
• R wave,
• S wave.
DR POTNURU SRINIVASA SUDHAKAR 31
32. • The P wave is caused by electrical potentials
generated when the atria depolarize before
atrial contraction begins.
DR POTNURU SRINIVASA SUDHAKAR 32
33. • The QRS complex is caused by potentials
generated when the ventricles depolarize
before contraction, that is, as the
depolarization wave spreads through the
ventricles.
DR POTNURU SRINIVASA SUDHAKAR 33
34. • Therefore, both the P wave and the
components of the QRS complex are
depolarization waves.
DR POTNURU SRINIVASA SUDHAKAR 34
35. • The T wave is caused by potentials generated
as the ventricles recover from the state of
depolarization.
DR POTNURU SRINIVASA SUDHAKAR 35
36. • This process normally occurs in ventricular
muscle 0.25 to 0.35 second after
depolarization, and the T wave is known as a
repolarization wave.
DR POTNURU SRINIVASA SUDHAKAR 36
40. • ECG machines record
the electrical activity
of the heart. They
also pick up the
activity of other
muscles, such as
skeletal muscle, but
are designed to filter
this out as much as
possible.
• Encouraging patients
to relax during an ECG
recording helps to
obtain a clear trace.
DR POTNURU SRINIVASA SUDHAKAR 40
42. • By convention, the
main waves on the
ECG are given the
names P, Q, R, S, T
and U.
• Each wave
represents
depolarization
(‘electrical
discharging’) or
repolarization
(‘electrical
recharging’) of a
certain region of
the heart.
DR POTNURU SRINIVASA SUDHAKAR 42
43. • The voltage changes detected by ECG
machines are very small, being of the
order of millivolts.
• The size of each wave corresponds to the
amount of voltage generated by the event
that created it:
• The greater the voltage, the larger the
wave .
P waves are small (atrial depolarization generates little voltage); QRS complexes are larger
(ventricular depolarization generates a higher voltage).
DR POTNURU SRINIVASA SUDHAKAR 43
44. • The ECG also allows you to calculate how long an
event lasted.
• The speed at which ECG paper moves through the
machine is standardized at a constant rate of 25
mm/s, so each small (1 mm) square on the ECG
represents 0.04 s, and each large (5 mm) square
represents 0.2 s.
DR POTNURU SRINIVASA SUDHAKAR 44
45. • This means that by measuring the width of a
wave, you can calculate the duration of the
event causing it.
• For example, the P waves in Figure are 2.5 mm
wide, so we can calculate that atrial
depolarization lasted for 2.5 × 0.04 s, or 0.10
s.
DR POTNURU SRINIVASA SUDHAKAR 45
47. Key points
• An ECG from a relaxed patient is much easier
to interpret.
• Electrical interference (irregular baseline) is
present when the patient is tense, but the
recording is much clearer when the patient
relaxes.
DR POTNURU SRINIVASA SUDHAKAR 47
48. Key points
• P waves are small (atrial depolarization
generates little voltage);
• QRS complexes are larger (ventricular
depolarization generates a higher voltage).
DR POTNURU SRINIVASA SUDHAKAR 48
49. ECG LEADS
• A "lead" is the electrical potential difference
between two electrodes placed on specific
points on the body.
• An ECG lead is a graphical description of the
electrical activity of the heart and it is created by
analyzing several electrodes.
• In other words, each ECG lead is computed by
analysing the electrical currents detected by
several electrodes.
DR POTNURU SRINIVASA SUDHAKAR 49
50. • Each chamber of the heart produces a
characteristic electrographic pattern.
• Since the electrical potentials over the various
areas of the heart differ, the recorded tracings
from each limb vary accordingly.
DR POTNURU SRINIVASA SUDHAKAR 50
51. • Each lead is given a name (I, II, III, aVR, aVL,
aVF, V1, V2, V3, V4, V5 and V6) and its
position on a 12-lead ECG is usually
standardized to make pattern recognition
easier.
DR POTNURU SRINIVASA SUDHAKAR 51
52. PARTS OF AN ECG
• The standard ECG has 12 leads.
• Six of the leads are considered “limb leads”
because they are placed on the arms and/or
legs of the individual.
• The other six leads are considered “precordial
leads” because they are placed on the torso
(precordium).
DR POTNURU SRINIVASA SUDHAKAR 52
53. • The six limb leads are called lead I, II, III, aVL,
aVR and aVF.
• The letter “a” stands for “augmented,” as
these leads are calculated as a combination of
leads I, II and III.
• The six precordial leads are called leads V1,
V2, V3, V4, V5 and V6.
DR POTNURU SRINIVASA SUDHAKAR 53
54. The Normal ECG
• A normal ECG contains waves, intervals,
segments and one complex.
DR POTNURU SRINIVASA SUDHAKAR 54
55. Wave
• A positive or negative deflection from baseline
that indicates a specific electrical event.
• The waves on an ECG include the P wave, Q
wave, R wave, S wave, T wave and U wave.
DR POTNURU SRINIVASA SUDHAKAR 55
56. Interval
• The time between two specific ECG events.
• The intervals commonly measured on an ECG
include the PR interval, QRS interval (also
called QRS duration), QT interval and RR
interval.
DR POTNURU SRINIVASA SUDHAKAR 56
61. Segment
• The length between two specific points on an
ECG that are supposed to be at the baseline
amplitude (not negative or positive).
• The segments on an ECG include the PR
segment, ST segment and TP segment.
DR POTNURU SRINIVASA SUDHAKAR 61
65. Complex
• The combination of multiple waves grouped
together.
• The only main complex on an ECG is the QRS
complex.
DR POTNURU SRINIVASA SUDHAKAR 65
66. Point
• There is only one point on an ECG termed the
J point, which is where the QRS complex ends
and the ST segment begins.
DR POTNURU SRINIVASA SUDHAKAR 66
67. • The P wave indicates atrial depolarization.
• The QRS complex consists of a Q wave, R wave
and S wave and represents ventricular
depolarization.
• The T wave comes after the QRS complex and
indicates ventricular repolarization.
DR POTNURU SRINIVASA SUDHAKAR 67
68. P Wave
• The P wave indicates atrial depolarization.
• The P wave occurs when the sinus node, also
known as the sinoatrial node, creates an action
potential that depolarizes the atria.
• The P wave should be upright in lead II if the
action potential is originating from the SA node.
DR POTNURU SRINIVASA SUDHAKAR 68
69. • As long as the atrial depolarization is able to
spread through the atrioventricular, or AV,
node to the ventricles, each P wave should be
followed by a QRS complex.
DR POTNURU SRINIVASA SUDHAKAR 69
70. QRS Complex
• A combination of the Q wave, R wave and S
wave, the “QRS complex” represents
ventricular depolarization.
DR POTNURU SRINIVASA SUDHAKAR 70
71. T Wave
• The T wave occurs after the QRS complex and
is a result of ventricular repolarization.
DR POTNURU SRINIVASA SUDHAKAR 71
72. What are ECG electrodes?
• Electrodes (small, plastic patches that stick to
the skin) are placed at certain spots on the
chest, arms, and legs.
• The electrodes are connected to an ECG
machine by lead wires.
DR POTNURU SRINIVASA SUDHAKAR 72
74. INITIAL PREPARATIONS
• Before making a 12-lead ECG recording, check
that the ECG machine is safe to use and has
been cleaned appropriately.
• Before you start, ensure you have an adequate
supply of:
• Recording paper
• Skin preparation equipment
• Electrodes
DR POTNURU SRINIVASA SUDHAKAR 74
75. INITIAL PREPARATIONS
• The 12-lead ECG should be recorded with the
patient in a semi-recumbent position
(approximately 45°) on a couch or bed in a
warm environment, while ensuring that the
patient is comfortable and able to relax.
• This is not only important for patient dignity,
but also helps to ensure a high-quality
recording with minimal artefact.
DR POTNURU SRINIVASA SUDHAKAR 75
76. Skin preparation
• In order to apply the electrodes, the patient’s
skin needs to be exposed across the chest, the
arms and the lower legs.
• Ensure that you follow your local chaperone
policy, and offer the patient a gown to cover
any exposed areas once the electrodes are
applied.
DR POTNURU SRINIVASA SUDHAKAR 76
77. • To optimize electrode contact with the patient’s
skin and reduce ‘noise’, consider the following
tips:
• Removal of chest hair It may be necessary to
remove chest hair in the areas where the
electrodes are to be applied. Ensure the patient
consents to this before you start. Carry a supply
of disposable razors on your ECG cart for this
purpose.
• Light abrasion Exfoliation of the skin using light
abrasion can help improve electrode contact. This
can be achieved using specially manufactured
abrasive tape or by using a paper towel.
DR POTNURU SRINIVASA SUDHAKAR 77
78. Skin preparation
• Skin cleansing An alcohol wipe helps to remove
grease from the surface of the skin, although this
may be better avoided if patients have fragile or
broken skin.
• Electrode placement Correct placement of ECG
electrodes is essential to ensure that the 12-lead
ECG can be interpreted correctly.
• Electrode misplacement is a common occurrence,
reported in 0.4% of ECGs recorded in the cardiac
outpatient clinic and 4.0% of ECGs recorded in
the intensive care unit.
DR POTNURU SRINIVASA SUDHAKAR 78
80. The standard 12-lead ECG consists of:
• Three bipolar limb leads (I, II and III)
• Three augmented limb leads (aVR, aVL and
aVF)
• Six chest (or ‘precordial’) leads (V1–V6)
DR POTNURU SRINIVASA SUDHAKAR 80
81. • 12 leads are generated using 10 ECG
electrodes,
• 4 of which are applied to the limbs and
• 6 of which are applied to the chest.
• The ECG electrodes are colour coded;
however, two different colour-coding systems
exist internationally.
DR POTNURU SRINIVASA SUDHAKAR 81
82. • International Electrotechnical Commission (IEC)
system uses the following colour codes:
• Right arm Red
• Left arm Yellow
• Right leg Black
• Left leg Green
• Chest V1 White/red
• Chest V2 White/yellow
• Chest V3 White/green
• Chest V4 White/brown
• Chest V5 White/black
• Chest V6 White/violet
DR POTNURU SRINIVASA SUDHAKAR 82
83. PLACEMENT OF THE LIMB
ELECTRODES
• Limb leads are made up of 4 leads placed on
the extremities:
• left and right wrist; left and right ankle.
• The lead connected to the right ankle is a
neutral lead, like you would find in an electric
plug.
• It is there to complete an electrical circuit and
plays no role in the ECG itself.
DR POTNURU SRINIVASA SUDHAKAR 83
85. PLACEMENT OF THE CHEST
(PRECORDIAL) ELECTRODES
• The six chest electrodes should be positioned
on the chest wall,which should be avoided,
include placing electrodes V1 and V2 too high
and V5 and V6 too low.
DR POTNURU SRINIVASA SUDHAKAR 85
86. The correct locations are:
• Chest V1 4th intercostal space, right sternal edge
• Chest V2 4th intercostal space, left sternal edge
• Chest V3 Midway in between V2 and V4
• Chest V4 5th intercostal space, mid-clavicular li
• Chest V5 Left anterior axillary line, same
horizontal level as V4
• Chest V6 Left mid-axillary line, same horizontal
level as V4 and V5
DR POTNURU SRINIVASA SUDHAKAR 86
88. FEMALE PATIENTS
• Placement of the chest electrodes can
sometimes pose difficulties in female patients
because of the left breast.
• By convention, the electrodes V4–V6 are
placed underneath the left breast.
DR POTNURU SRINIVASA SUDHAKAR 88
89. EINTHOVEN’S TRIANGLE
• Before we record the ECG, it is worth pausing
for a moment to consider how the electrodes
we have attached actually make the recording.
• As this is a little complicated, you can, if you
wish, skip this section for now and move on to
‘Recording the 12-Lead ECG’.
DR POTNURU SRINIVASA SUDHAKAR 89
91. • If we consider the three bipolar limb leads I, II
and III to begin with, these are generated by the
ECG machine using various pairings of the left
arm (LA), right arm (RA) and left leg (LL)
electrodes.
• The three limb leads are called ‘bipolar’ leads
because they are generated from the potential
difference between pairs of these limb
electrodes:
• Lead I is recorded using RA as the negative pole
and LA as the positive pole.
• Lead II is recorded using RA as the negative pole
and LL as the positive pole.
• Lead III is recorded using LA as the negative pole
and LL as the positive pole.
DR POTNURU SRINIVASA SUDHAKAR 91
92. • If you measure the potential differences in
each of these three limb leads at any one
moment, they are linked by the equation:
II = I + III
• In other words, the net voltage in lead II will
always equal the sum of the net voltages in
leads I and III.
• This is known as Einthoven’s law.
DR POTNURU SRINIVASA SUDHAKAR 92
93. • You can see this in action. In this ECG:
DR POTNURU SRINIVASA SUDHAKAR 93
94. • The R wave in lead I measures 5 mm, with no
significant S wave, giving a net size of 5 mm
(or 0.5 mV).
• The R wave in lead III measures 3.5 mm, with
an S wave of 2.5 mm, giving a net size of 1 mm
(or 0.1 mV).
DR POTNURU SRINIVASA SUDHAKAR 94
95. • Using Einthoven’s law:
• II = I + III
• II = 0.5 mV(I) + 0.1 mV(III)
• II = 0.6 mV
DR POTNURU SRINIVASA SUDHAKAR 95
96. THE OTHER THREE LIMB LEADS
• The other three limb leads, aVR, aVL and Avf.
• These leads are generated in a similar way to
leads I, II and III.
DR POTNURU SRINIVASA SUDHAKAR 96
97. • Hence:
• Lead aVR is recorded using negative
• Lead aVL is as the positive pole.
• Lead aVF is recorded as the positive pole.
DR POTNURU SRINIVASA SUDHAKAR 97
100. • The six chest leads (V1–V6) look at the heart
in a horizontal (‘transverse’) plane from the
front and around the side of the chest
DR POTNURU SRINIVASA SUDHAKAR 100
101. • The region of myocardium surveyed by each
lead therefore varies according to its vantage
point – leads V1–V4 have an anterior view, for
example, whereas leads V5–V6 have a lateral
view.
DR POTNURU SRINIVASA SUDHAKAR 101
102. • Electrical current flowing towards a lead
produces an upward (positive) deflection on the
ECG.
• Whereas current flowing away causes a
downward (negative) deflection.
• Flow towards a lead produces a positive
deflection, flow away from a lead produces a
negative deflection and flow perpendicular to a
lead produces a positive then a negative
(equipolar or isoelectric) deflection.
DR POTNURU SRINIVASA SUDHAKAR 102