Flashcards in CVS session 7- The ECG and Common Abnormalities Deck (21)
What is a 'lead'?
An electrical view of the heart
What are augmented leads?
They have 2 negative electrodes and 1 positive
How is one view achieved from an augmented lead?
Convert the two negatives to one.
Then invert this one negative and add to the positive to give the final view.
How many leads does a full ECG have and what are the components?
Leads I, II and III
Augmented leads VR, VL and VF
6 Chest leads V1-V6
How many electrodes do augmented leads have?
2 negative and 1 positive
How many electrodes do chest leads have?
3 negative and 1 positive
When are pathological Q waves found?
What is a consequence of atria not contracting in atrial fibrillation?
Clotting as blood pools in corners of atria.
When does Right axis deviation occur and which Leads R wave increases as a result?
When blood is hard to pump to the lungs, increasing the amount of muscle on the RHS.
Why does a bundle branch block lengthen and change the shape of the QRS complex?
The route of spread of depolarisation is altered as conducting pathways are damaged.
What happens to the ST segment in Angina?
What happens to the ST wave in an MI?
What are the two reasons that L axis deviation could occur?
-L ventricular hypertrophy
What is first degree heart block, and what is the abnormality on the ECG?
All of the signals generated at the SAN do reach the ventricles, but there is a delay somewhere along the pathway.
P-R interval elongation
What is second degree heart block and what is the ECG abnormality?
It is when there is a conduction problem between the atria and the ventricles which means that only some of the signals are reaching the ventricles.
Type 1- progressive lengthening of the P-R interval until no QRS follows.
Type 2- constant P-R intervals, but not all followed by QRS.
What is the third degree heart block and what is the ECG abnormality?
It is a complete conduction block between the atria and ventricles, therefore P waves are not associated with QRS complexes as atrial contraction is not necessarily followed by ventricular contraction.
P-R interval is irregular and the QRS complex is too.
What is Le bundle branch block and what is the ECG abnormality?
It is when the left branch of the huddle of His is blocked, meaning that depolarisation can't occur in the normal way from left to right.
An ectopic signal must therefore be depolarising the left ventricle, causing a widened QRS complex as it is slower at doing so.
Lead V6- wide QRS complex with a notched top.
What is Right bundle branch block and what is the ECG abnormality?
It is when there is a block of the right branch of the bundle of His. Depolarisation still occurs in the normal direction from left to right, but depolarisation of the R ventricle is slower, therefore causing a second R wave on lead V1.- RSR complex.
Which class of arrhythmia can carotid sinus pressure be used to treat?
What is a STEMI?
A myocardial infarction with ST elevation, pathological Q waves and T wave inversion.