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Week 126 - Chronic Stable Angina > ECGs and Conduction > Flashcards

ECGs and Conduction Flashcards

0
Q

What are the main generalised symptoms of heart block ?

A

SOB
Palpitations (caused by irregular heart beat)
Fainting
Can result in bradycardia

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1
Q

What is heart block?

A

A type of arrhythmia (a problem with rate or rhythm) whereby the electrical signals from the SA node to the AV node are disrupted / slowed

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2
Q

What is 1st degree heart block?

A

A split second delay in time taken for electrical impulse to pass from SA node to AV node

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3
Q

What is 2nd degree heart block?

A

Intermittent complete failure of excitation passing through the AV node or bundle of His (2/3 types of 2nd degree heart block)

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4
Q

What is Mobitz Type 2 heart block?

A

Most beats conducted with a constant PR interval but occasionally a P wave (atrial depolarisation/contraction) is not flowed by a QRS wave (ventricular depolarisation/contraction)

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5
Q

What happens in Mobitz Type 1 “Wenkebach” heart block?

A

Progressive lengthening of PR interval (delay between atrial and ventricular contraction) until failure of conduction (P wave NOT followed by QRS) then a conducted beat with short PR interval

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6
Q

What is 2:1 type 2nd degree heart block?

A

Where you get alternate conducted followed by non-conducted atrial beats. Twice as many P waves as there are QRS (some P waves will present hidden within T waves, showing as distorted T wave on ECG)

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7
Q

What can both Mobitz Type 2 and 2:1 lead to if not treated?

A

Complete (3rd degree) heart block

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8
Q

What is 3rd degree heart block?

A

Where atrial contraction is normal but NO beats are conducted to the ventricles

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9
Q

How do the ventricles contract with 3rd degree heart block?

A

Via a slow “escape mechanism”

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10
Q

What is the “escape mechanism” which occurs in 3rd degree (complete) heart block?

A

Where other sites in the heart (further down the conduction pathway) initiate depolarisation where SA node fails to or where there is a blockage in the depolarisation pathway.

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11
Q

What average depolarisation frequencies do foci in the atrial muscle or around the region of the AV node have (atrial / AV escape rhythm)?

A

50 per minute (resulting in bradycardia)

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12
Q

What average depolarisation frequency does a ventricular focus (ventricular escape rhythm) have and when would this focus take over?

A

30 per minute (very bradycardic).

Occurs when there is a failure of conduction through Bundle of His

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13
Q

Give an example of when acute complete heart block might be experienced.

A

During a myocardial infarction (MI)

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14
Q

Give an example of why chronic complete heart block might be experienced.

A

Due to fibrosis around the Bundle of His

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15
Q

Widening of the QRS complex is indicative of what?

A

A Bundle Branch Block

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16
Q

In what direction does the intraventricular septum normally depolarise?

A

Left to right

The left ventricle has a greater muscle mass and so exerts more influence on the ECG

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17
Q

An UPWARD deflection on an ECG signifies what?

A

That the electrical impulse / excitation is spreading TOWARDs that particular lead

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18
Q

A DOWNWARD deflection on an ECG signifies what?

A

Excitation / electrical impulse moving AWAY from that particular lead

19
Q

What is a normal PR interval?

A

0.12 - 0.2 seconds (3-5 small squares on ECG paper)

20
Q

What is the PR interval?

A

Time taken for excitation to spread from SA node, through AV node, down Bundle of His and through ventricles

21
Q

What does the QRS complex illustrate?

A

How long excitation takes to spread through the ventricles

22
Q

What is a normal QRS duration?

A

0.12 seconds (3 small squares)

23
Q

What is the correct calibration of an ECG?

A

1mV; should move stylus 1cm (2 large squares) vertically

24
What length of time does one large square denote?
200 milliseconds / 0.2 seconds
25
What length of time does one small square denote?
40 milliseconds
26
What length of time do 3 small squares denote?
0.12 seconds
27
When calibrated properly what does a tall P wave indicate?
Atrial hypertrophy
28
When calibrated properly what does a tall R wave indicate in left ventricular leads?
Ventricular hypertrophy
29
What do 5 large squares represent?
1 second
30
Why ECG changes are typical of pericarditis?
Widespread ST elevation (throughout limb and precordial leads) (May also get a Troponin rise)
31
What are the treatment options for a patient in AF?
Cardioversion (Direct Current synchronised shock) Pharmacological (Flecainide, Amiodarone - rhythm control; Beta-Blockers, calcium channel blockers or digoxin - rate control)
32
What major ECG change is seen in AF?
No defined P waves as no synchronised contraction
33
What is the characteristic change seen on an ECG in Atrial Flutter?
'Saw-toothed' appearance | Usually due to re-entry circuit in the right atrium
34
What ECG changes are typical of Left Atrial Hypertrophy?
Bifid P waves
35
Give some causes of LAH
HTN, aortic stenosis, mitral regurgitation | Though mitral stenosis in association with LVH is prob more common
36
What ECG features are seen with a Junctional Escape Rhythm?
Narrow complex QRS SA node rate 60-100bpm AV node rate 40-60bpm Ventricular rate 20-40bpm
37
What ECG changes are typical of Wolff-Parkinson-White syndrome?
Very short PR interval Broad complex QRS with "Delta wave" (slurred upstroke to QRS) (Accessory pathway)
38
What ECG changes are typical is RBBB?
"MaRRoW" or "MaRRooN" (latter perhaps more accurate) V1 - "M" (rSR) V6 - "W" or "N" (qRs) Wide QRS complexes
39
What ECG changes are typical is LBBB?
``` "WiLLiaM" or "ViLLhelM" (latter better) V1 - "V" (rS - dominant S wave) V6 - "M" (double peaked R) Absence of Q waves in lateral leads Wide QRS complexes ```
40
What ECG changes are typical of LVH?
Increased S wave in V1-V3 (downward deflection) Increased R wave in V4-V6 (upward deflection) Left axis deviation (Causes aortic stenosis, HTN, mitral or aortic regurgitation)
41
What ECG changes are typical of hyperkalaemia?
Peaked T waves Prolonged PR though P waves may be absent Bizarre QRS complexes which merge with P and T waves each side
42
Which leads do you compare to assess for left or right axis deviation?
Leads I and II | Leads aVL and aVF
43
Give two causes for left axis deviation and three causes for right axis deviation?
Left - LVH and LBBB | Right- RVH, PE and COPD
44
Which two arrest rhythms are shockable and which are not?
Shockable - VF and pulseless VT Non-Shockable - PEA and Asystole (IV adrenaline every 3-5mins)
45
List 3 things a Long QT rhythm can lead to
Palpitations Fainting Sudden Death due to VF (Implantable cardioverter used to treat)

Week 126 - Chronic Stable Angina (3 decks)

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