Download left ventricular hypertrophy

CLINICAL SKILLS UNIT
EDUCATIONAL LOOPS
BY
Centre of Medical Education
Acknowledgements
This Teaching e-loop is based on information and material
downloaded from the Queen’s University School of Medicine
website, http://meds.queensu.ca/courses/assets/modules/tsecg/ and information from MacLeod’s Clinical Examination,
Eleventh and tenth editions.
These sources are freely acknowledged and recommended
to all out students.
OBJECTIVES 1
1. Identify the waves and segments of an ECG
and relate the physiology of the wave
generation correctly (e.g., ventricular
depolarization)
2. Describe, define with data and recognise
the ECG patterns of right and left ventricular
hypertrophy and explain how the changes
occur
OBJECTIVES 2
3. Using the Queen’s University information
describe the electrical axis shown on an
ECG with a brief explanation
4. Describe the typical changes seen on an
ECG strip with myocardial ischaemia, after
an acute MI and a longer period after an MI
VENTRICULAR HYPERTROPHY
Ventricular hypertrophy occurs when there is extra strain
on the heart due to increased afterload. Afterload is the
resistance that needs to be overcome for the ventricle to
eject blood out through the aortic or pulmonary valves.
Therefore the two commonest causes are:
Hypertension
And
Aortic stenosis
Right ventricular hypertrophy is unusual!
VENTRICULAR HYPERTROPHY
The more muscle there is in a ventricle the larger the current
generated upon depolarization, and on an ECG recording the
heart’s axis shifts towards the hypertrophied side (for example,
right ventricle hypertrophy – right axis deviation). Therefore
normally the left ventricle dominates and the QRS complex
dominates over the left ventricle seen best in V5 and V6. Refer to
the Queen’s website for explanation of electrical axis of heart.
Lead I
aVF
AXIS
http://meds.queensu.ca/courses/assets/modules/ts-ecg/printableversion.html
LEFT VENTRICULAR HYPERTROPHY
V1 or V2
V5, V6 or aVL
R wave
S wave
If the depth or the S wave
and the height of the R
wave combined are greater
than 35 mm, or 3.5 mV,
there is left ventricular
hypertrophy!
Alternatively, a similar
criteria is satisfied if the R
wave in aVL is >12 mm or
1.2 mV.
LEFT VENTRICULAR HYPERTROPHY
V4
V2 = 3 mm and V4 = 5 mm
Left ventricular hypertrophy!!
V2
RIGHT VENTRICULAR HYPERTROPHY
The height of the R waves in the right chest leads, V1 and V2,
are increased and the depth of the S waves in the left chest
leads, V5 and V6, are increased. Note, above the increased
depth of the S wave is seen best in V5.
DILATED RIGHT ATRIUM
Inspect P waves in leads I, II and III
4 mm or 0.4 mV
P waves in the standard limb leads shall not
exceed 3 mm, if they do in II the right atrium
is dilated. If the P wave is inverted by more
than 1 mm in V1 the left atrium if dilated
CAN YOU THINK OF TWO CONDITIONS
WHICH CAUSE THE RIGHT AND LEFT
ATRIA TO BECOME DILATED?
WHICH VENTRICULAR HYPERTROPHY?
So, which ventricle is hypertrophied here?
WHICH VENTRICULAR HYPERTROPHY?
And, which ventricle is hypertrophied here?
WHAT WAS THE MOST LIKELY CAUSE?
This adult patient had an uncorrected VSD
GIVE CAUSES FOR PATIENTS A AND B
V1
V4
V2
V5
V3
V6
Patient A had an ejection murmur in the right
IC II space
Patient B’s BP was 160/90 mmHg
MYOCARDIAL ISCHAEMIA
RECOGNISING MYOCARDIAL INFARCTION AND ISCHAEMIA
Q
S
T
There are THREE keys to recognising an MI and myocardial
ischaemia
MYOCARDIAL ISCHAEMIA
THE THREE KEYS:
1. Is the ST segment elevated (acute MI) or depressed
(ischaemia)?
2. Development of a Q wave is indicative of an MI
3. Changes in V1 – V6, lead I and AVL indicates anterior wall
infarction (left anterior descending coronary artery).
Changes in lead II, III and AVF, indicates inferior wall
infarction (right coronary artery, or a branch, such as
posterior descending).
There are some other changes to see and there some other causes, but in Phase II, lets start with
something you can remember!!
MYOCARDIAL ISCHAEMIA
This 55 year-old man was on a treadmill and he was coupled to
an ECG and above is a snapshot of the strip, what is
immediately obvious?
GOOD YOU GOT IT!!
MYOCARDIAL INFARCTION
OK, the ST segment is clearly elevated (C and D) and through the
sequence A – F its character changes. Note too, the T wave
changes and there also appears a Q wave! The Q wave shall be
longer than 0.04s and more than 25% of the size of the R wave
(this illustration fails to meet that criterion).
MYOCARDIAL INFARCTION SEQUENCE
A
Normal ECG, moments before the MI
B&C
Minutes after MI, huge T wave and/or
elevated ST segment
D
Hours after, Q wave appearance, ST still
elevated but T wave inversion
CHANGES BEST SEEN
IN LEADS OPPOSITE
MUSCLE MOST
AFFECTED.
E
Days after, Pathological Q waves and T wave
inversion
F
Weeks after, Q + T wave STILL abnormal!!
That wasn’t so difficult was it? So what about a
few formative Qs without the answers, please take
a copy of this e-loop and review the slides and get
the answers in your own time
Continue to the next slide!
Warning, some of the following you have not
covered yet, but allow you to see our expectations
at the end of the cardiovascular module
FORMATIVE QUESTIONS
A 60 year-old man who experiences central chest pain
lasting one hour before subsiding and has become
breathless.
WHAT has affected WHICH part of his heart and which
blood vessel and WHAT pathology is causing this?
FORMATIVE QUESTIONS
A 45 year-old woman who has started having episodes of
fainting over the last two days.
WHAT has affected WHICH part of her heart and what
are the atrial and ventricular rates?
FORMATIVE QUESTIONS
A 70 year-old man with palpitations, breathlessness and
a history of a previous MI
WHAT is the heart rate?
DISREGARD THE ARRHYTHMIA – YOU HAVE NOT
SEEN THIS BEFORE
FORMATIVE QUESTIONS
A 55 year-old woman with weight loss, intolerance of
heat and protruding eyes, she also complained of
palpitations
WHAT was her cardiac problem, WHAT was the cause
and WHAT was her heart rate
WELL DONE!
These simple ECG interpretations
represent the expectations for a Phase
II student, you may meet them in an
OSCE or a multiple choice question!!