Basic EP Flashcards
The flow of electric current is measured in:
Amperes, Amps = 1 coulomb/sec
What is the term used to denote the total opposition to flow of alternating current in a circuit:
Impedance or resistance (ohms)
Impedance
- term used to denote opposition to DC current flow
- changes with the frequency, amount of capacitance, resistance, and inductance
What is the most common DC electric power source?
Battery
DC current
- only travels in one direction
- flows steadily from - to +
Electric battery current has a frequency of:
0 Hz
The elimination of vibrations at certain frequencies is accomplished through the use of electronic devices known as:
filters
ECG amplifiers
- incorporate a band pass filter
- cuts off low frequencies <0.1 Hz and high frequencies >100 Hz
When a DC defibrillator “charges” it stores electrical energy in its:
Capacitors
EP lab external defibrillators should be tested by
Discharging paddles into a dummy load
Patient accidentally shocked on his T wave could cause
VF
The watt second (or joule) is a unit of
- energy
- 1 Watt = 1 volt x 1 amp
Defibrillator charge
50-360 joules
Frequency units
Hz = cycles/sec
Force units
Newton = m*kg/sec^2
Energy or work units
joule = m^2kg/sec^2
also Ergs or Watt Sec
Power units
Watt = m^2kg/sec^3 (also rate of doing work)
Ohms law
V=IR
(voltage) = (current)(resistance)
used to measure pacemaker lead impedance
For maximum electrical safety, the ECG monitored patient should be _____, and the monitor chassis should be _____, or nonconductive.
ungrounded, grounded
In the ICU, when recording an intracardiac ECG from a pacing electrode or pericardiocentesis needle in the heart, it is safest to:
Use a battery powered monitor or only use an instrument known to have a leakage current of less than 10 uA
When you plug in an electric instrument, you are alarmed when sparks fly from the wall outlet. The most likely electrical safety problem is a:
Machine off-on switch was left on
The prefix “centi” corresponds to:
1/100
prefix from smallest to largest
nano, micro, milli, centi
nano
10-9
micro
10-6
milli
10-3
centi
10-2
kg to lbs
kg = lbs/2.2 lbs = 2.2*kg
Degrees to Celsius formula
C = (5/9)(F-32) F = (9/5)C+32
Formula to calculate heart rate
rate = 60,000/RR interval
