ECG tutorials Flashcards

1
Q

What are the 2 causes of wide QRS?

A
  • bundle branch block (due to cell to cell conduction instead of Purkinje system)
  • Ventricular origin (not along the conducting system and hence cell to cell conduction): ventricular premature beat, ventricular tachycardia, ventricular escape beat
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2
Q

What does right axis deviation look like in the ECG?

A

Negative lead I & aVL

Positive lead III & aVF

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3
Q

What are the 5 causes of narrow QRS tachycardia?

A
  • atrial fibrillation (10% of population >80yo)
  • sinus tachycardia
  • ## atrioventricular nodal reentrant tachycardia
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4
Q

Describe atrial fibrillation

A
  • irregularly irregular pulse (c.f. regularly irregular pulse may be due to ectopic beats)
  • no p waves (atrium is not depolarised in an organised fashion)
  • fast & chaotic within atria
  • high frequency signals around pulmonary veins (pulmonary vein isolation by electrophysiology; electrocuting all around pulmonary veins & will cure AF)
  • conduction via AV node is selective as it is hit irregularly by the atria & due to refractory period (AV node has a longer refractory period than atria)
  • ventricular rhythm is determined on the refractory period of AV node
  • Px: palpitation, dyspnoea (due to reduced filling time -> high end diastolic pressure in atria -> back flow into pulmonary veins & high pressure -> fluid out of pulmonary capillaries; congestion & poor diffusion)
  • mostly asymptomatic. Only symptomatic with tachycardia
  • worse symptoms in anyone who already have trouble filling the heart e.g. left ventricular hypertrophy, mitral stenosis, HOCM

Rate control (by working on the AV node)

  • Non-dihydropyridine, verapamil, diltiazem
  • beta blockers
  • digoxin

Rhythm control:

  • amiodarone
  • sotalol
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5
Q

What is the scoring system for major bleeding risk in pt who are anticoagulated?

A

HAS-BLED score

  • Hypertension history (>160mmHg systolic)
  • Abnormal renal/liver function
  • Stroke Hx
  • Bleeding Hx (anaemia/predisposition to bleeding)
  • Labile INRs
  • Elderly (>65yo)
  • Drug therapy (antiplatelet agent, NSAID)
  • Alcohol intake (>8 drinks/week)
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6
Q

Early beat, Wide QRS & funny looking T wave is likely to be:

A

Ventricular ectopic/premature beat

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7
Q

What are the group of leads?

  • inferior
  • anterior
  • lateral
A

Inferior: II, III, aVF (right coronary artery)
Anterior: V1-5 (LAD)
Lateral: I, aVL, V5, V6 (circumflex)

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8
Q

What does ST elevation mean?

A

Myocardial infarction directly underneath the group of leads (a lead above the part of infarction receives the current going through the infarction). There’s reciprocal depression as the current going through the infarction at another site is perceived as going away from it.

  • Transmural infarction
  • Pericarditis
  • Physiological
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9
Q

What often blocks/occludes a coronary artery?

A

Thrombus (NOT atheroma) due to a plaque rupture (fibrous cap destruction exposing the underlying collagen, cholesterol etc, aggregating platelets).

1% of MI due to emboli
1% of MI due to artery dissection

Unknown mechanisms:

  • why the plaques rupture.
  • why the person has a plaque at that particular point.
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10
Q

Is there a screening test for CAD?

A

No. You cannot pick up CAD early.

If you are not symptomatic, exercise tests will not detect the small plaques.

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11
Q

What is the side effect of tPA as a Rx for AMI?

A

Major bleeding. E.g. 1% intracerebral bleeding

It reduces morbidity by >5% in MI. Benefit far outweights than the SE. Hence only give if you’re really sure if the pt is having an AMI (not an angina) by looking at the ECG STEMI. (not in a NSTEMI)

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12
Q

When does T inversion occur (in STEMI & NSTEMI)?

A

24 hours post STEMI.

NSTEMI: Might have normal ECG, ST depression or T wave inversion.

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13
Q

(3) Rx of NSTEMI

A
This could be unstable angina. 
Rx:
- antianginal
-anti coagulant
- antipaltelet
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14
Q

(1) Rx of STEMI

A

Definite diagnosis of AMI

Rx:
Urgent reperfusion; thrombolysis or PCI

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15
Q

Where does the right bundle run? Hence what area infarct will cause RBBB?

A

In the septum.

Anterior septal infarct will cause right bundle branch block

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16
Q

What structures of the heart are affected in RCA infarct?

A

AV node, sinus node

AV block is usually transient

17
Q

What is acute inferior infarct associated with? How do you Rx the association?

A

Sinus bradycardia

Partly due to vagal stimulation. Hence Rx with atropine (not Norad)

18
Q

ST elevation in 2 different territories. DDx

A

Infarction

Pericarditis

19
Q

What are R, S & Q waves?

A
  • Every positive QRS: an R wave
  • Negative wave after an R wave: S wave.
  • Only if the initial part of QRS is negative: Q wave. Territory underneath is infarcted. It doesn’t necessarily follow ST elevation. It can occur simultaneously sometimes. ST elevation & T inversion usually go away but Q waves will last forever.
20
Q

What is a Type 2 MI?

A

Due to severe hypoperfusion but not due to coronary artery.

Much less common due to autoregulation of circulation to preserve myocardial & brain cells.

21
Q

When can you have ST elevation? (6)

A
LVH
LBBB
Pericarditis
Hyperkalaemia
AMI
Brugada
22
Q

What is trifascicular block? (3) components

A

1st degree AV block
Left anterior hemiblock/Left axis deviation
RBBB

23
Q

What is bifascicular block? (2) components

A

Left anterior hemiblock/Left axis deviation

RBBB

24
Q

Indications for pacemakers

A

Bifascicular/trifascicular block + syncope

25
Q

What is left anterior hemiblock?

A

LAD without inferior infarct

26
Q

(2) Features of Left ventricular hypertrophy on ECG

A

T wave inversion

Stretched QRS