Term
| what is the normal QRS width? |
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Definition
| 2-3 small squares or between 0.8-0.12 secs |
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Term
| what is the standard speed ECG paper runs at? |
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Definition
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Term
| each large square on ECG paper is equivalent to 0.2 seconds. what is each small square equivalent to? |
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Definition
0.04 seconds
also the vertical scale on an ECG is standardardised at 1millivolt per cm |
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Term
| if you have a regular rhythm describe two methods used to get ventricular rate from ECG |
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Definition
1st method: count number of small squares between 2 QRS complexes and divide the number into 1500. e.g. 21 small squares thus 1500/21 = 71
2nd method: count the large squares between 2 QRS complexes and divide the number into 300. e.g. 4 larges squares thus 300/4 = 75 |
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Term
| how would you measure ventricular rate with an irregular rhythm? |
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Definition
| count 30 large squares then count the number of QRS complexes in the 30 large squares and multiply the number by 10. |
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Term
| what is the normal PR interval? |
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Definition
| 3-5 small squares or 0.12-0.20 secs |
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Term
| which term describes a prolonged PR interval >0.20secs? |
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Definition
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Term
| name the two types of 2nd degree heart block and differentiate between them |
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Definition
Morbitz type 1 - AKA Wenckebacke. PR interval progressively lengthens until a QRS complex is dropped
Morbitz type II = The PR Interval in constant but a QRS interval is periodically dropped. |
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Term
| describe the action of atria and ventricles in 3rd degree heart block |
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Definition
| they are producing impulses independently. p waves and QRS complexes are regular but QRS complexes are wide ~0.20sec (normal 0.08-0.12secs) |
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Term
| what is ST elevation indicative of? |
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Definition
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Term
| what is ST depression indicative of? |
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Definition
ischeamia.
normal ST values are raised no more than 2-3 small squares above the isoelectrical line |
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Term
| peaked T waves are characteristically seen in which condition? |
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Definition
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Term
| Where would you see changes in an anterior MI? |
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Definition
| v1-6. The main coronary artery affected is the LAD |
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Term
| where would you see changes in ECG in a later MI? |
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Definition
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Term
| where would you see changes in ECG for an inferior MI? |
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Definition
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Term
| Which leads would you see changes for a posterior MI? |
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Definition
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Term
| what do pathological Q waves signify? |
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Definition
| sign of previous MI. Result of absence of electrical activity |
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Term
| when do cardiac troponin levels increase? |
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Definition
| 3-12 hours from onset of pain. peak at 24-48 hours. return to baseline 5-14 days |
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Term
| what is an early marker of MI when troponin levels aren't available yet? |
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Definition
| myoglobin - but poor specificity |
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Term
| when troponin test isn't available MB-CK can be used instead. is this more or less sensitive and when does it peak? |
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Definition
| less sensitive that troponin. increases 3-12 hours from pain onset. peaks at 24 hours and returns to base line 48-72hours |
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