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Medicine > ECGs-how-to > Flashcards

ECGs-how-to Flashcards

1
Q

What directions are lead 1, 2, 3, RA, AVR, aVF, AVL and v1-6?

A
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2
Q

What parts of the heart/vessels do the different ecg leads correspond with?

A
  • 1, avl, +/- V5-6 = lateral heart = left circumflex
  • V1-4 = anterior = LAD
  • 2, AVF, 3 = inferior = right coronary artery
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3
Q

What is the systematic process for looking at ECGs?

A
  1. Patient details/calibration
  2. Rate
  3. Rhythm
  4. Axis
  5. P wave
  6. PR interval
  7. QRS complexes
  8. ST segment
  9. T waves
  10. QT interval
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4
Q

What should be looked for regarding patient details and calibration?

A
  • patient details
  • history

Calibration: 10mV and 25 mm/s

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5
Q

What should be looked at regarding rate on ecg?

A
  • calculate qrs peaks x6 for rate
  • >100 = tachycardic
  • <60 = bradycardic
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6
Q

What should be looked at regarding rhythm on ecg?

A
  • are there P waves before QRS?
  • is P-R constant?

if yes then is sinus!

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7
Q

What would you see for rhythm regarding AF?

A
  • there are no P waves
  • it is Irregularly irregular
    • can use paper to check if regularly irregular

can see F waves - A pattern of irregular undulations of the base line in an electrocardiogram that is indicative of atrial fibrillation.

Tx: cause - structrue or systemic (hyperthyroid); control - electric DC; anticoagulation - chadvasc >2 = be on warfarin or doac e.g. rivoraoxaban

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8
Q

What would be seen regarding atrial flutter?

A
  • these are regular (usually, can be other)
    • e.g. regularly irreg
    • but faster than usual e.g. more often than ventrivles e.g. for 4 atrial beats:1 ventricular beats
  • but sawtooth
  • flutter waves ~200-300, beat regularly but
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9
Q

What is the difference between atrial fibrillation and atrial flutter?

A

Atrial flutter and atrial fibrillation are both abnormal heart rhythms. …

In atrial fibrillation, the atria beat irregularly.

In atrial flutter, the atria beat regularly, but faster than usual and more often than the ventricles, so you may have four atrialbeats to every one ventricular beat.

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10
Q

What is sick sinus arrythmia?

A
  • pathological sinus arrthymia
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11
Q

What is a normal sinus arrhythmia?

A
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12
Q

How can you tell axis deviation?

A
  • left axis deviation
    • legs leaving
  • right axis deviation
    • reaching/legs together
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13
Q

What can cause left axis deviaton?

A

left axis deviation can be caused by

  • LV hypertrophy

slots of deviation to move axis

RV infarct will also pull axis to LHS (like releasing part of elastic band)

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14
Q

What causes right axis deviation?

A
  • left ventricle infarct
  • cor pulmonale / right ventricular hypertrophy
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15
Q

How do you examine P waves on an ecg?

A
  • look at lead II
    • shows p waves best
  • height <2.5ss
  • Width <3 ss
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16
Q

What could tall P waves indicate?

A
  • e.g. height > 2.5 ss

Tall indicated RA enlargement/hypertrophy

the commonest RA hypertrophy cause is COPD

= tf called p.pulmonale

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17
Q

What do bifid p waves: broad p waves indicate?

A
  • Left atrial enlargement
  • found from rheumatic fever affecting the mitral valve –>
  • LA enlargement is an early-mod sign of mitral stenosis
  • = p. mitrale
  • mitral stenosis can flip into AF - so AF would be a late sign while LA enlargement is early/mod sign of mitral stenosis
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18
Q

Why is ecg calibration important?

A
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19
Q

What does each small square on ecg represent?

What does a large square on ecg represent?

A
20
Q

How do you inspect the PR -interval?

A

PR interval should be 2-5ss

  • if it is longer e.g. delay
  • then this mans there is a delay in conduction between the SA –> AV node
21
Q

When may PR interval be shortened?

A
  • Wolff Parkinson White synx
    • condition where there is an accessory pathway between atrium and ventricles
  • you see a short PR interval, delta wave and QRS prolongation

the SA node goes so you get a P wave but then is blocked by AV node because your acecssory can conduct - get the start of delta wave (like a notch just before/within qrs) and get your R wave after

Get cardio assesment

cardiac hx: broken into cardiovascular, conduction, cardiomyopathy

22
Q

what happens in a prolonged PR interval?

A

A prolonged PR interval is >5 ssq

  • Called 1st degree heart block

this can be caused by meds e.g. beta blockers, Ca2+ inhib e.g. amiodarone, digoxin

  • treat 1st deg HB is symptomatic e.g. LOC and syncope
    • e.g. change drug regeime
  • NB: athletes (from increased heart mass) may have this signs, if on exercise it shortenes again - the PR should shorten on exercise
23
Q

What is 2nd degree heart block type 1?

A
  • 2nd degree heart block
  • where the PR interval prolongs and then drops
  • prolongs and drobs is Wenkeback or mobitz type 1

get a Hx and exercise test

mobitz T1/wenke tells you that AV node is getting worse as PR is getting longer then skipping

24
Q

What is 2nd degree heart block type 2?

A
  • Mobitz type 2 heart block
  • increased PR interval (not getting longer each time though)
  • shows p waves not being conducted
  • irregular heart beat
  • p wave not conducted on whole
  • can get a ratio of #Pwave:#QRS

NB: any patient from heat block t2 onwards e..g 3rd needs tx irrespective of symx or not

(t1 mobitz you treat if its symptomatic)

25
Q

What is 3rd degree heart block?

A
  • Stokes adams syndrome
  • COMPLETE heart block / 3rd degree AV block
  • so the SA node is going - there are lots of p waves @80bpm
  • but no AV response due to complete block
    • so automacity happens for AV / ventricle contaction - but this is a slower rate ~40bpm
  • no correlation between p waves and qrs

Hx: syncope (LOC >10sec); can often feel failt before

Tx: pacemaker;

26
Q

What should be looked at regarding the QRS complexes on ECG?

A
  • width - should be around 3ss (e.g. they should be narrow)
  • narrow QRS = supraventricular problem e.g. AVNRT, AVRT, WPW(delta waves)

impulses from ventricle will look broad (borad = ventricular problem)

  • broad QRS caused by:
    • Bundle Branch Bclok,
    • endocrine/thyroid,
    • VT
27
Q

How do you identify RBBB vs LBBB?

A

looking at broad QRS >3ss and their QRS height in…

… V1 and V6

if V1 is mostly positive = RIGHT bbb

  • which side is more broad? MARROW
    • M in V1, V2 (RHS)and W in V5,6 (LHS)

if v1 is neg = LEFT

  • WILLIAM
    • W in V1,2 (RHS) and M in V5,6 (LHS)

NB: the criteria for MI is new onset left BBB

  • LBBB is never normal and is usually assoc. w/ischaemic HD or structural HD
28
Q

What does a tall QRS indicate?

What does a broad QRS indicate?

A
  • left ventricular hypertrophy
  • (>3 squares/>3mV)
    • LVH with strain is not MI is due to LVH (e.g. ic blood presure)
    • T wave inversion left ventricle are thick so outside in needs to treavel in muscle ischaemia
    • look at S wave in V1, V2 to tallest R wave in V5,6 if >3s
  • Broad QRS = ventricular pathway broken or nor being used at all e.g LBBB QRS= left going down in V1= WILLIAM
  • Broad QRS = not likely from AV node e.g. Ectopic and alternative pathway
29
Q

What are pathological Q waves?

A

Q waves indicate an old MI or ongoing MI - >2 small squares tall

[wide= > 40 milliseconds (one small box) or size= > 25% of the QRS complex amplitude.]

you will see the q waves in concordant leads e.g. LAD/anterior V1-V4; lef circumflex/lateral 1, AVL, V5,6; RCA/inferior 2,3,AVF

30
Q

What are the signs of MI?

A
  • Pathological q waves
  • posterior MI (and chest pain): tall r waves in V1 and V2; will see ST depression in posterior stemi
    • remember the RCA also does a bit posterior so look on leads to see
  • St elevation in STEMI
  • and ST segment depression in NSTEMI - inverted/anormal T waves
    • (depression = ischaemia, reversible tissue dysfunction)
    • remember T waves are always inverted in AVR and V1 - castle look on ecg for actual t wave inversion
  • Pericarditis = all st elevation (due to relative PR depression - looks like diffuse ST seg elevation)
    • Hx: leaning forward, pleuritic, (pmhx of resp infection)
      • Tx pericarditis: colcine and nsaids ->> conservative therapy until resolves on its own
  • T-wave changes including low-amplitude T wavesand abnormally inverted T waves may be the result of many cardiac conditions such as myocardial ischemia, myocarditis, mitral valve prolapse, or ventricular strain.
31
Q

What should be considered regarding QT interval?

A
  • in cardiology the Q-T interval should not be larger than 2 boxes wide
  • if Q-T is abnormally short or long there is a risk of developing verious types of ventricular arrhythmias
  • some QT prolongation can cause polmorphic ventricular tachycardia with a characteristic twist of the QRS complex around the isoelectric baseline - called Torsades de Pointed (TdP)
  • this can be caused by anti histamines, anti psychotics, erythromycin
32
Q

What should be considered regarding T waves on ECG?

A
  • if there are tall/tented T waves = hyperkalaemia
    • ​also signs of hyperkalaemia = low flat Ps, prolonged PR, broad, QRS, tall tented T waves
    • Hx: could be crush injury that relases K+ from muscles
  • If there are shortened flat = hypokalaemia/thyroid/hypothermia
33
Q

What would someone with a pacemaker’s ECG look like?

A
  • Pacing spike before QRS
  • e.g. any impusle from QRS will look wide
  • so have to go with hx not ecg
34
Q

What test should be done in ABCD approach?

A

ABG, ECG

remember if cardiac out of TROP, ECG and HX - HX is most improtnant

trop is only way to see unstable angina from NSTEMI

  • VT –> VF –> death : needs pacing
35
Q

What is a bifasciular block?

trifascicular?

A

RBBB (marrow) + left axis deviation or posterior hemiblock

Trifasciular block = bifascicular block and 1st degree heart block - e.g. prolongs

36
Q

What are the STEMI mimics?

A
  • Pericarditis
  • widespread ST elevation in all domains - pericarditis is said to look saddleshaped vs MI which is tombstone
  • PR depression

IN an NSTEMI ST depression is everywhere unlike STEMI where its more specific - there is also T wave inversion (except AVR and V1 which is normally inverted- castle image)

37
Q

What is strain pattern on ecg?

A
  • ST depression
  • T wave inversion
  • FOLLOWING a large height QRS
  • *contextual*
  • this strain pattern is on LHS or RHS or hypertrophy +/- axis deviaiton (leaving, reaching)
38
Q

What is the Sokolow-Lyon criteria?

A
  • left ventricular hypertrophy criteria
    • Largest S wave - V1 or V2
    • Largest R wave - V5 or V6
    • sum is greater than 35mm (7 large squares)
39
Q

How can you tell an ectopic beat on ECG?

A
  • will look completely different
40
Q

What are the causes of LBBB?

A
  • Ishcaemia heart diseae (coronary artery disease/coronary heart disease)
  • HTN
  • Aortic stenosis
  • Cardiomyopathy
41
Q

What are the causes of P.mitrale?

A
  • Bifid P wave
  • enlarged left atrium
  • LA hypertrophy e.g. mitral stenosis
  • enlarged LA to incrases contribution to P wave contour
  • P mitrale because of mitral valve stenosis being the commonest cause of its appearance on ECG
42
Q

What is P.pulmonale?

A
  • peaked p wave
  • reflects process causing RA to be hypertrophied
  • e.g. tricuspid regurgitation and pulmonary HTN
  • they hypertrphied to push at increased pressure
  • so peaked p wave = cor pulmonale / p pulmonale
43
Q

What is malar flush?

A
  • plum red discolouration of high cheeks
  • from mitral stenosis- from CO2 retention and its vasodilatory effects
    • also SLE or polycythemia vera
  • features of Mitral stenossi: SOB, fatigue, malar flush, accentuated on LHS, mid diastolic murmur (mid filling)
44
Q

What are the signs of a silent MI in diabetes?

A
  • no chest pain or perspiration
  • but (maybe) fatigue, uneasiness, slugishness or SOB
45
Q

When can a cardiac MRI be used?

A

in MI and coronary artery disease (IHD)

  • would show regi wall motion irregularities in infarcted area
46
Q

What do you see in hyper/hypo kalaemia?

A

Hyperkalaemia

  • tall peaked t waves with narrow base
  • wide QRS and no P waves

hypokalaemia

  • in hypokalaemia U have no Pot and no T but a long PR and a long QT
    • U waves, boarderline PR interval, st depression, long QT
      • u waves from repolarisation of purkinje fibres
    • small or absent t waves (flat, occ, inverted)

Medicine (6 decks)

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