This document provides information about ECG diagnosis and interpretation. It discusses lead placement and what each lead represents. It then covers normal sinus rhythm and various cardiac conditions like WPW syndrome, AF, and RBBB. Next, it discusses waveforms and intervals seen on ECGs. Finally, it details the 10 rules for a normal ECG, characteristics of AMI, axis determination, and other diagnostic criteria.
ECG in Emergency Department - Advances in ACS ECGDr.Mahmoud Abbas
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ECG in Emergency Department -Advances in ACS ECG. Lecture presented by Dr Hesham Ibrahim at the Egyptian Critical Care Summit , the leading educational event and medical exhibition in Egypt.
ECG in Emergency Department - Advances in ACS ECGDr.Mahmoud Abbas
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ECG in Emergency Department -Advances in ACS ECG. Lecture presented by Dr Hesham Ibrahim at the Egyptian Critical Care Summit , the leading educational event and medical exhibition in Egypt.
This presentation covers few basic things about ECG, especially for UG Medical students like ECG leads, normal ECG waves, axis of ECG and how to look for common ECG misplacements.
How to read ECG systematically with practice strips Khaled AlKhodari
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This lecture simplifies the steps of reading ECG systematically. It starts with a simple heart anatomy and the logical steps that should be followed to perfect ECG reading without missing any abnormality. Finally, there are some practice ECG strips that include but not only MI, STEMI, Wellens syndrome, Pulmonary embolism, LVH, arrhythmias... and others
An electrocardiogram (ECG or EKG) records the electrical signal from your heart to check for different heart conditions. Electrodes are placed on your chest to record your heart's electrical signals, which cause your heart to beat. The signals are shown as waves on an attached computer monitor or printer
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Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
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Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
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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
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
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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 Departmentâs official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
Basavarajeeyam is an important text for ayurvedic physician belonging to andhra pradehs. It is a popular compendium in various parts of our country as well as in andhra pradesh. The content of the text was presented in sanskrit and telugu language (Bilingual). One of the most famous book in ayurvedic pharmaceutics and therapeutics. This book contains 25 chapters called as prakaranas. Many rasaoushadis were explained, pioneer of dhatu druti, nadi pareeksha, mutra pareeksha etc. Belongs to the period of 15-16 century. New diseases like upadamsha, phiranga rogas are explained.
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ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
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Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Adv. biopharm. APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMSAkankshaAshtankar
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ADVANCED BIOPHARMACEUTICS & PHARMACOKINETICS : UNIT 5
APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMS By - AKANKSHA ASHTANKAR
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.
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TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Recomendaçþes da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS â Objetivos do Desenvolvimento SustentĂĄvel e a EstratĂŠgia Global para a SaĂşde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pĂłs-natais devem expandir-se para alĂŠm da cobertura e da simples sobrevivĂŞncia, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pĂłs-natais essenciais e de rotina prestados Ă s mulheres e aos recĂŠm-nascidos, com o objetivo final de melhorar a saĂşde e o bem-estar materno e neonatal.
Uma âexperiĂŞncia pĂłs-natal positivaâ ĂŠ um resultado importante para todas as mulheres que dĂŁo Ă luz e para os seus recĂŠm-nascidos, estabelecendo as bases para a melhoria da saĂşde e do bem-estar a curto e longo prazo. Uma experiĂŞncia pĂłs-natal positiva ĂŠ definida como aquela em que as mulheres, pessoas que gestam, os recĂŠm-nascidos, os casais, os pais, os cuidadores e as famĂlias recebem informação consistente, garantia e apoio de profissionais de saĂşde motivados; e onde um sistema de saĂşde flexĂvel e com recursos reconheça as necessidades das mulheres e dos bebĂŞs e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendaçþes novas e jĂĄ bem fundamentadas sobre cuidados pĂłs-natais de rotina para mulheres e neonatos que recebem cuidados no pĂłs-parto em unidades de saĂşde ou na comunidade, independentemente dos recursos disponĂveis.
Ă fornecido um conjunto abrangente de recomendaçþes para cuidados durante o perĂodo puerperal, com ĂŞnfase nos cuidados essenciais que todas as mulheres e recĂŠm-nascidos devem receber, e com a devida atenção Ă qualidade dos cuidados; isto ĂŠ, a entrega e a experiĂŞncia do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendaçþes da OMS de 2014 sobre cuidados pĂłs-natais da mĂŁe e do recĂŠm-nascido e complementam as atuais diretrizes da OMS sobre a gestĂŁo de complicaçþes pĂłs-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências Ê contemplada.
Recomendamos muito.
Vamos discutir essas recomendaçþes no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação sĂł estĂĄ disponĂvel em inglĂŞs atĂŠ o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
- 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
3. Lead Position
â˘
A typical ECG report shows the cardiac cycle from 12
different vantage points (I, II, III, aVR, aVL, aVF, V1-V6), like
viewing the event electrically from 12 different locations (like
a 3D perspective).BUT only 10 electrodes are used.
â˘
Lead I represents activity that is going from the right arm to
the left arm
Lead II represents activity that is going from the right arm to
the left leg
Lead III represents activity that is going from the left arm to
the left leg
â˘
â˘
â˘
â˘
â˘
â˘
â˘
â˘
â˘
â˘
â˘
aVL is placed on the left arm (or shoulder)
aVF is placed on the left leg (or hip)
aVR is placed on the right arm (or shoulder)
V1- 4th intercostal space to the right of sternum
V2- 4th intercostal space to the left of sternum
V3- halfway between V2 and V4
V4- 5th intercostal space in the left mid-clavicular line
V5- 5th intercostal space in the left anterior axillary line
V6- 5th intercostal space in the left mid axillary line
30. Rule 2
1.0
R
The width of the QRS complex
should not exceed 110 ms, less
than 3 little squares
Millivolts
0.5
T
P
Q
0
S
-0.5
QRS
0
200
400
Milliseconds
600
31. Rule 3
I II III
aVR aVL aVF
The QRS complex should be
dominantly upright in leads I and II
32. Rule 4
I II III
aVR aVL aVF
QRS and T waves tend to have the
same general direction in the limb
leads
35. Rule 7
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The ST segment should start isoelectric except in V1 and
V2 where it may be elevated
36. Rule 8
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The P waves should be upright in I, II, and V2 to V6
37. Rule 9
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
There should be no Q wave or only a small q less than
0.04 seconds in width in I, II, V2 to V6
38. Rule 10
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
The T wave must be upright in I, II, V2 to V6
39. What is the heart rate?
â˘www.uptodate.com
â˘(300 / 6) = 50 bpm
40. What is the heart rate?
â˘www.uptodate.com
â˘(300 / ~ 4) = ~ 75 bpm
41. What is the heart rate?
â˘(300 / 1.5) = 200 bpm
42. 10 Second Rule
As most EKGs record 10 seconds of rhythm per page,
one can simply count the number of beats present on the
EKG and multiply by 6 to get the number of beats per 60
seconds.
This method works well for irregular rhythms.
43. What is the heart rate?
â˘The Alan E. Lindsay ECG Learning Center ; http://medstat.med.utah.edu/kw/ecg/
â˘33 x 6 = 198 bpm
44. Characteristic changes in AMI
â˘
â˘
â˘
â˘
â˘
ST segment elevation over area of damage
ST depression in leads opposite infarction
Pathological Q waves
Reduced R waves
Inverted T waves
45. ST elevation
⢠Occurs in the early stages
R
ST
P
Q
⢠Occurs in the leads facing the
infarction
⢠Slight ST elevation may be
normal in V1 or V2
46. Deep Q wave
⢠Only diagnostic change of
myocardial infarction
R
ST
⢠At least 0.04 seconds in duration
P
T
Q
⢠Depth of more than 25% of
ensuing R wave
47. T wave changes
⢠Late change
R
⢠Occurs as ST elevation is
returning to normal
ST
P
⢠Apparent in many leads
T
Q
48. Bundle branch block
Anterior wall MI
I II III
aVR aVL aVF
Left bundle branch block
V1 V2 V3
V4 V5 V6
I II III
aVR aVL aVF
V1 V2 V3
V4 V5 V6
49. Sequence of changes in evolving AMI
R
R
T
R
ST
ST
P
P
Q S
P
T
Q
1 minute after onset
Q
1 hour or so after onset
A few hours after onset
R
ST
P
ST
P
T
Q
A day or so after onset
T
P
T
Q
Later changes
Q
A few months after AMI
53. Location of infarct combinations
I
aVR
LATERAL OR HIGH
II
aVL
LATERAL
V1
V4
SEPTAL
ANT
V2
V5
ANT
V3
III
INFERIOR
aVF
V6
LAT
54. Diagnostic criteria for AMI
â˘
â˘
â˘
â˘
â˘
Q wave duration of more than 0.04
seconds
Q wave depth of more than 25% of
ensuing r wave
ST elevation in leads facing infarct (or
depression in opposite leads)
Deep T wave inversion overlying and
adjacent to infarct
Cardiac arrhythmias
55. Quick & Easy AXIS DETERMINATION
ď§ Left axis deviation - negative QRS in lead AVF
I
I
AVF
AVF
ď§ Right axis deviation - negative QRS in lead I
I
I
AVF
AVF
ď§ Severe Right axis deviation negative QRS in BOTH
lead I and AVF
I
I
AVF
AVF
56. The QRS Axis
By near-consensus, the normal
QRS axis is defined as ranging
from -30° to +90°.
-30° to -90° is referred to as a left
axis deviation (LAD)
+90° to +180° is referred to as a
right axis deviation (RAD)
58. The Quadrant Approach
1. Examine the QRS complex in leads I and aVF to determine if they
are predominantly positive or predominantly negative. The
combination should place the axis into one of the 4 quadrants
below.
59. Quadrant Approach: Example 1
The Alan E. Lindsay ECG
Learning Center
http://medstat.med.utah.ed
u/kw/ecg/
Negative in I, positive in aVF ď RAD
60. Quadrant Approach: Example 2
The Alan E. Lindsay ECG
Learning Center
http://medstat.med.utah.ed
u/kw/ecg/
Positive in I, negative in aVF
ď
Predominantly positive in II
Normal Axis (non-pathologic LAD)
ď
QRS waveform nomenclature
The ECG consists of a small deflection called the P wave, arising from the atria, a more complicated deflection called the QRS complex due to ventricular depolarisation and a final T wave resulting from repolarisation of the ventricles.
The QRS complex of waves is the largest deflection of the ECG and is always spiky in shape. All sharp deflections resulting from electrical activation of the ventricles are called QRS complexes. However, these waves can vary immensely in size, and arrangement.
The QRS complex is very important when diagnosing myocardial infarction. In order to be able to describe these complexes, a nomenclature for the waves is needed. This can be done using combinations of the letters q, r, s, Q, R, S, lower case letters denoting small waves and upper case larger waves.
The first positive wave is labelled with r or R
Any second positive wave is labelled r´ or R´
A negative wave which follows an R wave or r wave is labelled S or s
A negative wave that precedes an R or r wave, is labelled a q or Q wave
Any wave that is entirely negative is labelled qs or QS.
Using these rules and nomenclature all QRS complexes can be described, enabling more accurate diagnosis.
The 10 rules for a normal ECG
For an ECG to be determined as normal, Chamberlain has described 10 rules which must be met.1 The next ten slides will outline these rules.
Rule 1
As described in Module 3, the PR interval is the time from initiation of depolarisation of the atria to initiation of the depolarisation of the ventricles. The PR interval should be 120 to 200 milliseconds, or 3 to 5 little squares. A longer PR may imply a block in conduction and a shorter interval indicates a vulnerability to arrhythmias.
Rule 2
The QRS complex is due to depolarisation of the ventricles. The width of the QRS complex should not exceed 110 ms (less than 3 little squares). A wider QRS is sometimes seen in healthy people, but may represent an abnormality of intraventricular conduction.
Rule 3
The QRS complex should be dominantly upright in leads I and II. Slight disparities are likely to be acceptable.
Rule 4
The QRS and T waves tend to have the same direction in the standard leads.
Rule 5
All waves are negative in lead aVR. This has to be so: aVR represents electrical activity as âseenâ from the right shoulder. The sinus node is placed top right in the heart nearest the right shoulder, and the electrical activity is moving downwards and leftwards towards the left ventricle.
Rule 6
The normality of QRS complexes recorded from the precordial leads is dependent on both morphological and dimensional criteria.
Rule 7
The ST segment should start isoelectric except in V1 and V2 where it may be elevated.
Rule 8
In leads I, II, and V2 to V6 the P waves should be upright.
Rule 9
There should be no Q wave or only a small q less than 0.04 seconds in width in I, II, V2 to V6.
Rule 10
In leads I, II, and V2 to V6 the T wave must be upright.
Characteristic changes in AMI
The 12-lead ECG is the most useful investigation for confirming the diagnosis of acute myocardial infarction, locating the site of the infarct and monitoring the progress. It is therefore very important to know the changes that occur in this situation.
The only diagnostic evidence of a completed myocardial infarction seen on the ECG are those in the QRS complexes. In the early stages changes are also seen in the ST segment and the T wave, and these can be used to assist diagnosis of myocardial infarctions.
Shortly after infarction there is an elevation of the ST segment seen over the area of damage, and opposite changes are seen in the opposite leads. Several hours later pathological Q waves begin to form, and tend to persist. Later the R wave becomes reduced in size, or completely lost. Later still, the ST segment returns to normal, and at this point the T wave also decreases, eventually becoming deeply and symmetrically inverted.
Although these changes occur sequentially, it is very unlikely they will all be clearly observed by the paramedic or GP. A patient can present at any stage and a progression through the ECG changes will not be seen. It is important to recognise these features as they occur rather than in association with each other. All these changes imply myocardial infarction, and will be discussed in more detail over the next few slides.
ST elevation
ST segment elevation usually occurs in the early stages of infarction, and may exhibit quite a dramatic change.
ST elevation is often upward and concave, although it can appear convex or horizontal. These changes occur in leads facing the infarction.
ST elevation is not unique to MIs and therefore is not confirming evidence. Basic requirements of ST changes for diagnosis are: elevation of at least 1 mm in two or more adjoining leads for inferior infarctions (II, III, and aVF), and at least 2 mm in two or more precordial leads for anterior infarction. You should be aware that ST elevation can be seen in leads V1 and V2 normally. However, if there is also elevation in V3 the cause is unlikely to be physiological.
Deep Q wave
The only diagnostic changes of acute myocardial infarction are changes in the QRS complexes and the development of abnormal Q waves. However, this may be a late change and so is not useful for the diagnosis of AMI in the pre-hospital situation.
Remember that Q waves of more than 0.04 seconds , or 1 little square, are not generally seen in leads I, II or the precordial leads.
T wave inversion
The T wave is the most unstable feature of the ECG tracing and changes occur very frequently under normal circumstances, limiting their diagnostic value.
Subtle changes in T waves are often the earliest signs of myocardial infarction. However, their value is limited for the reason above, but for approximately 20 to 30% of patients presenting with MI, a T wave abnormality is the only ECG sign.
The T wave can be lengthened or heightened by coronary insufficiency.
T wave inversion is a late change in the ECG and tends to appear as the ST elevation is returning to normal. As the ST segment returns towards the isoelectric line, the T wave also decreases in amplitude and eventually inverts.
Bundle branch block
Bundle branch block is the pattern produced when either the right bundle or the entire left bundle fails to conduct an impulse normally. The ventricle on the side of the failed bundle branch must be depolarised by the spread of a wave of depolarisation through ventricular muscle from the unaffected side. This is obviously a much slower process and usually the QRS duration is prolonged to at least 0.12 seconds (for right bundle branch block) and 0.14 seconds (for left bundle branch block).
The ECG pattern of left bundle branch block (LBBB) resembles that of anterior infarction, but the distinction can readily be made in nearly all cases. Most importantly, in LBBB the QRS is widened to 140 ms or more. With rare exceptions there is a small narrow r wave (less than 0.04 seconds) in V1 to V3 which is not usually seen in anteroseptal infarction. There is also notching of the QRS best seen in the anterolateral leads, and the T wave goes in the opposite direction to the QRS in all the precordial leads. This combination of features is diagnostic. In the rare cases where there may be doubt assume the correct interpretation is LBBB. This will make up no difference to the administration of a thrombolytic on medical direction but for the present will be accepted as a contraindication for paramedics acting autonomously (see later slide).
Right bundle branch block is characterised by QRS of 0.12 seconds or wider, an s wave in lead I, and a secondary R wave (Râ) in V1. As abnormal Q waves do not occur with right bundle branch block, this remains a useful sign of infarction.
Sequence of changes in evolving AMI
The ECG changes that occur due to myocardial infarction do not all occur at the same time. There is a progression of changes correlating to the progression of infarction.
Within minutes of the clinical onset of infarction, there are no changes in the QRS complexes and therefore no definitive evidence of infarction. However, there is ST elevation providing evidence of myocardial damage.
The next stage is the development of a new pathological Q wave and loss of the r wave. These changes occur at variable times and so can occur within minutes or can be delayed. Development of a pathological Q wave is the only proof of infarction.
As the Q wave forms the ST elevation is reduced and after 1 week the ST changes tend to revert to normal, but the reduction in R wave voltage and the abnormal Q waves usually persist.
The late change is the inversion of the T wave and in a non-Q wave myocardial infarct, when there is no pathological Q wave, this T wave change may be the only sign of infarction.
Months after an MI the T waves may gradually revert to normal, but the abnormal Q waves and reduced voltage R waves persist.
In terms of diagnosing AMI in time to make thrombolysis a life-saving possibility, the main change to look for on the ECG is ST segment elevation.
Location of infarction and its relation to the ECG: anterior infarction
As was discussed in the previous module, the different leads look at different aspects of the heart, and so infarctions can be located by noting the changes that occur in different leads. The precordial leads (V1â6) each lie over part of the ventricular myocardium and can therefore give detailed information about this local area. aVL, I, V5 and V6 all reflect the anterolateral part of the heart and will therefore often show similar appearances to each other. II, aVF and III record the inferior part of the heart, and so will also show similar appearances to each other. Using these we can define where the changes will be seen for infarctions in different locations.
Anterior infarctions usually occur due to occlusion of the left anterior descending coronary artery resulting in infarction of the anterior wall of the left ventricle and the intraventricular septum. It may result in pump failure due to loss of myocardium, ventricular septal defect, aneurysm or rupture and arrhythmias. ST elevation in I, aVL, and V2â6, with ST depression in II, III and aVF are indicative of an anterior (front) infarction. Extensive anterior infarctions show changes in V1â6 , I, and aVL.
Location of infarction and its relation to the ECG: inferior infarction
ST elevation in leads II, III and aVF, and often ST depression in I, aVL, and precordial leads are signs of an inferior (lower) infarction. Inferior infarctions may occur due to occlusion of the right circumflex coronary arteries resulting in infarction of the inferior surface of the left ventricle, although damage can be made to the right ventricle and interventricular septum. This type of infarction often results in bradycardia due to damage to the atrioventricular node.
Location of infarction and its relation to the ECG: lateral infarction
Occlusion of the left circumflex artery may cause lateral infarctions.
Lateral infarctions are diagnosed by ST elevation in leads I and aVL.
Location of infarction: combinations
The previous slides discussed the changes that occur in typical anterior, inferior and lateral infarctions. However, the area infarcted is not always limited to these areas and infarctions can extend across two regions. For example, an anterior infarction which is also on the lateral side of the heart is known as an anterolateral infarction.
ST segment elevation in leads I and aVL represent a lateral infarction
Anteroseptal infarctions show ST segment elevation in leads V1 to V4.
ST elevation in V4 to V6 is typical of an anterolateral infarction
ST elevation in II, III and aVF is typical of inferior infarction.
Diagnostic criteria for AMI
Myocardial infarction is the loss of viable, electrically active myocardium. Diagnosis can therefore be made from the ECG. However, only changes in QRS complexes can provide a definite diagnosis. Changes in each of the leads must be noted, along with symptoms, as both are important in making a diagnosis.
Excluding leads aVR and III, Q wave duration of more than 0.04 seconds or depth of more than 25% of the ensuing r wave are proof of infarction. Other criteria are the development of QS waves and local area low voltage r waves.
Although these are useful diagnostic features, there are additional features that are associated with myocardial infarction as have been described in the previous slides. These include ST elevation in the leads facing the infarct, ST depression (reciprocal) in the opposite leads to the infarct, deep T wave inversion overlying and adjacent to the infarct, abnormally tall T waves facing the infarct, and cardiac arrhythmias. These extra features may aid in the diagnosis of myocardial infarction from an ECG.