BHRS ECG/EGM challenge Flashcards
What lead checks at follow-up give away possible RV lead perforation?
Unipolar RV threshold > bipolar RV threshold. Threshold is expected to increase in perforation
What happens to the lead impedance in case of perforation?
Lead impedance would drop as there is decreased resistance to the current, lead outside of myocardium, if there is pericardial effusion.
What could happen to the R wave in case of lead perforation?
Drop in the R wave
Why would the unipolar threshold be higher than the bipolar threshold in lead perforation?
In bipolar pacing the stimulus moves from the device to the lead tip (cathode) and then returns to the ring electrode (anode). In unipolar pacing the anode is the device itself and the stimulus returns via the body tissues. If the cathode is surrounded by pericardial effusion this lowers the unipolar impedance significantly as it is not in contact with myocardial tissue and also significantly increases the output as the circuit is extracardiac and not able to directly stimulate the myocardium. If the bipolar anode is still within the myocardium (figure 6b) the bipolar threshold remains lower but outside normal range as the heart is still able to be stimulated at high outputs when the impulse returns to the ring electrode. If the bipolar ring also passes beyond the myocardium (figure 6c) then loss of bipolar capture and sensing can also occur.
What is pseudo pseudo fusion?
Pseudo-pseudofusion is when an intrinsic QRS is overlapped with an atrial rather than a ventricular pacing output, giving the appearance of pseudofusion.
