Topic 5.1 and 5.2 (Introduction to Therapeutic Devices) Flashcards
What is the most common way to treat Atrial and Ventricular fibrillation?
by applying defibrillation which uses external electrical source to effectively stop the heart so that SA node and trigger normal cycle
What is the typical size of the metal surface of paddles on a defibrillator?
8-10cm in diameter
What is the typical voltage range and energy range for defibrillators?
1) 1000-6000V
2) 50-400 J
Why is an inductor used in a discharging circuit in a defibrillator?
to obtain the desired discharging shock waveform
What is the effect of changing the inductor to a higher value in a discharging circuit?
The discharged voltage will be sustain at a high voltage for a longer period of time and also it will dip below negative for a short period of time before it hit zero volts
What is an automatic external defibrillator (AED)?
it is a device that gives visual and vocal instructions on how to operate a device and measure the ECG in a patient to detect ventricular fibrillation to allow the operator to apply shock to restart the heart
What is a heart block?
it is an interruption in the normal conduction pathway of the heart
What is a first degree heart block?
it is the delayed conduction path of the SA to the AV node
what is a second degree heart block?
it is when some impulses from the SA node reach the AV nodes and some do not. can be seen on ECG when P wave got no QRS complex.
What is a third degree heart block?
the SA node and AV node do not work together and the AV node becomes the natural pacemaker and the heart rate is sustained at 40-60 BPM even after excercise.
What can we do to treat third degree heart blocks?
The cardiologist can implant an artificial pacemaker that delivers electrical impulses to the heart to speed up the heart rate and restore normal contractions
What are the 2 types of pacemaker?
1) Asynchronous pacemaker (Fixed rate pacemaker)
2) Synchronous pacemaker
What is the 2 differences between the 2 pacemaker?
1) asynchronous pacemaker do no have feedback loop while synchronous pacemaker has a feedback loop
2) asynchronous pacemaker do not have and electrode to sense patient ECG signals while synchronous has
What is the typical lifespan of pacemaker battery and what specification does it rely on?
1) 15 Years
2) it relies on the ampere-hour rating
