Most common form of SVT - Correct answer-AVNRT
AVNRT Characteristics - Correct answer-1. prolonged PR interval in the beat that starts reentry 2. HR:
150-250 bpm 3. neck pounding, palpitations, light-headiness, near-syncope 4. narrow QRS 5. abrupt
onset and termination of episodes 6. more common in women 7. frequently presents after age 20
rheobase - Correct answer-the lowest point on a strength-duration curve at an infinitely long pulse
duration
chronaxie time - Correct answer-pulse width at twice the rheobase value; approximates the most
efficient stimulation pulse duration
resting (transmembrane) potential - Correct answer-voltage difference between the inside and outside
of the cell fiber
Single chanmber, ventricular pacing is usually only indicated in the presence of what? - Correct answer-
chronic AF
Atrial naturetic peptide (ANP) aka brain naturetic peptide (BNP) - Correct answer-a substance produced
by the atrium when the muscle is subjected to higher than normal pressure --> increased levels of ANP
may also be pointing to VVI pacing or loss of atrial capture/synchrony as the culprit
sites used for the ablation of the slow pathway with AVNRT - Correct answer-range from midseptal
region between the compact AV mnode and the CS os to the posteriolateral region around the os
,successful AVNRT ablation indicated by: - Correct answer-1. an accelerated junctional rhythm w/ 1:1 VA
conduction during the burn 2. increase in refractoriness of the anterograde AV node 3. elimination or
alteration in dual AV nodal physiology
3 devices with no effect to pacemakers - Correct answer-microwave, CT scan/ultrasound, x-rays
5 devices that may affect a pacemaker - Correct answer-MRI, defibrillator, cardioversion, cautery/RF
ablation, radiation therapy
devices that cause transient or 1 beat inhibition to pacing - Correct answer-electronic article
surveillance, cell phones, arc welding, airport metal detectors, TENS nurve stimulator, electronic
appliances
series resistance formula and example - Correct answer-Rt= R1 + R2; lead fracture (which leads to
increase in impedance)
parallel resistance formula and example - Correct answer-Rt = R1R2/R1+R2; lead insulation defect
(which leads to decrease in impedance)
small load refers to a constant _______ device; large load refers to a constant ___________ device -
Correct answer-current; voltage
PPM indicated when: - Correct answer-1. symptomatic 2. HR< 40 3. documented asystole > 3 sec (can be
asymptomatic with 2 and 3)
ICD Capacitance Range - Correct answer-90-150 micro farad
DFT thresholds may be lower for _____ output capacitors - Correct answer-Smaller
Low capacitor means high voltage, which means faster waveform
, Higher Impedance (results in) - Correct answer-Higher threshold and DFT voltage (results in)
Low Impedance (trends towards) - Correct answer-Higher tilt (trends towards)
Higher Impedance results in - Correct answer-Higher voltage
Steroid-eluting elctrodes: acute threshold phase is relatively ______ compared to non-steroid
electrodes. - Correct answer-flat
Steroid-eluting electrodes: initial capture threshold is _____ to non-steroid electrodes. - Correct answer-
similar
4 cons to silicone rubber - Correct answer-1. high friction coefficient
2. absorbs lipids
3. more thrombogenic
4. large diameter compared to polyurethane
GOOD polyurethane - Correct answer-55D
BAD polyurethane - Correct answer-80A
3 cons to polyurethane - Correct answer-1. cannot be repaired
2. relatively stiff
3. hard to make
3 causes of pacemaker syndrome - Correct answer-1. loss of AV synchrony
2. sustained retrograde conduction
3. single ventricular rate when rate modulation is required for exercise