CVS Physio Pt 2/2 (ECG n PE) Flashcards
What does ECG measure?
(Using your hand actions) Show the “views” of Leads I, II, III and Leads aVR, aVL and aVF.
Where are the 10 electrodes in 12-lead ECG placed?
(i) Draw out the ECG 12 boxes strip.
(ii) Which ECG box corr to which leads? (draw the pattern on a pic of the ECG).
(iii) Which leads (thus which boxes) then corr to (eg. probs w) which coronary arteries?
1 small box = ?s
1 big box (aka 5 small boxes) = ?s on ECG ppr
Outline the cardiac cycle. (draw ‘pie chart’)
Note: the ELECTRICAL ACTIVITY during each cardiac cycle is represented as a graph on ECG ppr
What does ‘ups’ - positive deflections and ‘downs’ - negative deflections mean in ECG ppr?
Interpret what these mean:
(i) P wave
(ii) QRS complex
(iii) T wave
(iv) PR interval
(v) ST segment (“from end of S to start of T”)
(vi) QT interval (“from start of Q to end of T”)
(vii) RR interval
HINT: RMB THE WAVES, WTV YOU SEE ON ECG = ELECTRICAL ACTIVITY –> you can outline the direction location of the conduction system of heart (specialised muscle fibres transmitting these impulses)
Does depolarisation or repolarisation give rise to systole?
depol –> systole
Does depolarisation or repolarisation give rise to diastole?
repol –> diastole
What’s the formula for using RR interval to calculate HR?
300/(no. of big sq btw RR)
normal HR of 75bpm = ? big squares on ECG ppr
4
Bradycardia = ? bpm = >? big squares on ECG ppr
Tachycardia= ? bpm = <? big squares on ECG ppr
Interpret what these mean:
1. missing P wave
2. prolonged PR interval
3. prolonged QRS interval
4. Tall QRS complex
5. prolonged QT interval (“from start of Q to end of T”)
6. Tall T wave
7. ST segment elevation (“from end of S to start of T”)
8. ST segment depression (“from end of S to start of T”)
9. Prolonged RR interval
IMPNOTE: rmb all these CG waves are the CONDUCTION SIGNALS in conduction syste of heart, not much of what muscular movement is happening - change perspective
Note: why does hyperkalemia cause tall t waves if repolarisation involves the efflux of K+ from cell into an extracellular environment (with increased K+ concentration)?
Ans: During repolarization, K⁺ ions leave the cell through K⁺ channels. In hyperkalemia, the high extracellular K⁺ concentration decreases the driving force for K⁺ to leave the cell, but the increased extracellular K⁺ also enhances K⁺ conductance (opening of more K⁺ channels). This can lead to a quicker repolarization phase.
The quicker repolarization results in the T wave on the ECG being sharper and more peaked, as the cells return to their resting state more rapidly and uniformly.
Explain how to calculate the patient’s cardiac axis to diagnose left/ right axis deviation of heart.
(Explain the steps!)
Apex beat:
1. created by?
2. during __ systole
3. anatomical location on chest wall?
4. What do these mean:
- stronger amplitude of apex beat
- sustained apex beat
- laterally and inferiorly displaced apex beat
- absence of apex beat
What does JVP represent?
Why can JVP be representative of RA pressure?
Name the 3 waves and 2 descents in JVP graph. What do they each represent?
What does:
(i) giant a wave
(ii) giant c wave
mean?
When do the 2 normal heart sounds occur?
(^think wrt cardiac cycle pie chart)
When do the 2 abnormal heart sounds occur?
What is:
(i) physiologic S2 splitting
(ii) pathologic S2 splitting
and when are they heard?
What gives rise to murmurs?
What does it mean (which valve got prob, and what fxnal prob) when there’s a systolic vs diastolic murmur?
Systolic murmur:
- mitral/ tricuspid regurg
- aortic/ pulmonary stenosis
Diastolic murmur:
- aortic/ pulmonary regurg
Within the class of ‘systolic murmurs’, explain the 2 types:
(i) Ejection systolic murmur
vs
(ii) Pansystolic murmur
- when it happens in systole?
- what (fxnal valve defect(s)) causes it?
(i) Ejection systolic murmur
- happens during the second part of a systole – the ejection
- due to blood being squeezed through narrower lumen
- ^due to: aortic/ pulmonary STENOSIS
(Recall: systole = compress + eject)
(ii) Pansystolic murmur
- happens throughout systole (compress + eject)
- due to mitral/ tricuspid REGURGITATION
What are heaves? What pathology allows you to hear heaves?
What are thrills? What pathology allows you to hear thrills?
