Data interpretation Flashcards
Consider the following statements regarding this ECG:
The normal speed the paper travels at is 50 mm/s
False. The normal speed for an ECG to travel is 25 mm/s. Therefore 5 large squares (each 5 mm wide) represent 1 second.
Consider the following statements regarding this ECG:
The length of the QRS complex increases with increasing LV muscle mass
False. The amplitude (mV) of the QRS complex increases with LV muscle mass (hypertrophy). Prolongation of the QRS complex indicates a conduction delay (Bundle Branch Block).
Consider the following statements regarding this ECG:
One volt is usually represented by a 10 mm vertical deflection of the ECG
False. 10 mm on the y axis represents 1 mV.
Consider the following statements regarding this ECG:
The QT interval is measured from the start of the QRS complex to the beginning of the T wave
False. The QT Interval is measured from the start of the QRS to the end of the T wave. When considering if it is prolonged it should also be corrected for heart rate.
Consider the following statements regarding this ECG:
The smallest square on an ECG represents 0.2 s
False. The smallest square is 0.04 s, or 40 ms.
Consider the following statements about the ECG:
U waves represent sinoatrial (SA) node repolarization
False. The P wave represents atrial depolarization. The U wave is a small deflection following the T wave, which probably represents repolarization of the papillary muscles and is most commonly seen in hypokalaemia.
Consider the following statements about the ECG:
The T wave represents ventricular repolarization
True
Consider the following statements about the ECG:
The QT interval reflects the duration of the ventricular refractory period
True. The refractory period is divided into the absolute and relative refractory period. During the absolute refractory period another action potential can not be elicited. In the relative refractory period a action potential can be elicited in certain circumstances.
Consider the following statements about the ECG:
The PR interval represents AV nodal conduction delay
True
Consider the following statements about the ECG:
The height of a normal P wave is 0.3 mV
False. The normal P wave is less than 2.5 mm which represents 0.25 mV.
Consider the following statements about the QRS complex:
It is associated with ventricular repolarization
False. The QRS complex is associated with ventricular depolarization. The T wave is associated with ventricular repolarization.
Consider the following statements about the QRS complex:
It is absent in 3rd Degree Heart Block
False. 3rd Degree Heart Block is Complete Heart Block, where there is complete dissociation between atrial and ventricular depolarization.
Consider the following statements about the QRS complex:
It is normally longer that 200 ms
False. The normal QRS duration is less than 0.12 s (3 small squares). Greater than this indicates presence of a bundle branch block.
Consider the following statements about the QRS complex:
It is associated with isovolumetric ventricular relaxation
False. The QRS occurs just prior to isovolumetric contraction as ventricular contraction follows ventricular depolarization.
Consider the following statements about the QRS complex:
It is prolonged in conduction defects such as Bundle Branch Blocks
True. The normal QRS duration is less than 0.12 s (3 small squares). Greater than this indicates presence of a Bundle Branch Block.
Now, consider the following statements about using ECG monitoring intraoperatively:
In a patient with a permanent pacemaker an alternative method to the ECG for measuring heart rate should be employed (e.g. pulse oximeter)
True. A patient with a pacemaker is at risk of Pulseless Electrical Activity (PEA) which would not be detected unless an alternative method of measuring heart rate is employed.
Now, consider the following statements about using ECG monitoring intraoperatively:
The electrodes consist of silver and silver chloride
True
Now, consider the following statements about using ECG monitoring intraoperatively:
CM5 is more sensitive at detecting arrhythmias
False. CM5 is more sensitive at detecting ventricular ischaemia.
Now, consider the following statements about using ECG monitoring intraoperatively:
When utilising CM5 monitoring, electrodes are placed on the manubrium, clavicle and at the V5 position
True. C = Clavicle, M = Manubrium, 5 = V5.
Now, consider the following statements about using ECG monitoring intraoperatively:
Diathermy is frequently a problem causing interference
True. Diathermy will cause interference with ECG monitoring.
Consider the following statements about QT prolongation:
It is seen in patients with hypercalcaemia
False. This is seen in patients with hypocalcaemia. Hypercalcaemia shortens the QT interval.
Consider the following statements about QT prolongation:
It can seen in patients receiving penicillin
False. It is associated with macrolide antibiotics. It is also associated with Class III antiarrhythmics (e.g. amiodarone), anti-histamines and tricyclic antidepressants.
Consider the following statements about QT prolongation:
It is seen in patients with Romano-Ward syndrome
True. Romano Ward syndrome is an example of hereditary prolonged QT syndrome.
Consider the following statements about QT prolongation:
It predisposes patients to Torsade-de-pointes
True. Torsade-de-pointes is a form of Ventricular Tachycardia with a changing axis. It can present as syncope, or deteriorate into VF and sudden death. Treatment is as per ALS algorithm, with the addition of intravenous magnesium.