Pacemakers Flashcards
What is a heartblock
a problem with your heartbeat signal mocing from upper to lower part of your heart. The conduction is either too slow to each AV node or doesn’t fire at all.
What is first degree heart block
The time between the P and QRS waves is too long (greater than 0.20s without disruption of atrial to ventricular conduction)
Asymptomatic
twice the risk of developing atrial fibrillation
What is second degree block, type I (Mobitz I)
The P-R interval becomes progressively longer with each beat, until AV node no longer conducts an impulse from the atria.
Caused by parasympathetic excess (AV conduction is slowed)
What is a common risk for those with Mobitz type I
bradycardia leading to hypotension. If this occurs, type I blocks respond well to atropine
Bradycardia
abnormally slow heart action
Transcutaneous pacing
temporary cardiac pacing using pads or paddles applied externally to the chest
What is seocnd degree heart block, type II
The P-R interval remains consistent, but a QRS complex doesn’t follow every p-wave.
2 to 4 P waves may occur before ventricular deplorization
Requires placement of pacemaker
What type of heart block is mostly seen in patients with structural heart disease
Mobitz type II (second degree type II)
It is often associated with myocardial ischemia and fibrosis or sclerosis of the myocardium (hardening, thickening, or low blood flow to the heart muscle)
What are the three positions of the pacemaker and what do they stand for
I: What chamber is being paced (none, atrium, ventrical, or dual)
II: What chamber are we sensing? (none, atrium, ventrical, or dual)
III: Response to sensing (none, trigger, inhibit, dual)
Describe DDD Pacing scenerio
atrium and ventricular pacing and sensing with dual response.
Will act if the intrinsic atrial and ventricular rates are below the LRL
Pacemaker mode DDD. What happens if the atrial rate is slower than LRL
the device will pace the atrium after a delay while inhibiting ventricular pacing if the ventricular event is sensed
Pacemaker mode DDD. What happens if the atrial sensed event is faster than LRL but no ventricular event
device inhibits atrial pacing but triggers ventricular pacing after a delay
What is VVI mode for pacemaker
Ventricular-paced: The pacemaker sends a pulse if no natural beat is detected.
Ventricular-sensed: It detects natural ventricular beats.
Inhibited: If a natural beat occurs, the pacemaker does not fire.
What are the 6 main parts of a pacemaker
- Leads
- Sensing circuit
- Waveform circuit
- Processor Module
- Telemetry transceiver
- Battery
what is a harmonic
a sinusoidal wave with a frequency that is a positive integer multiple of the fundamental frequency of a periodic signal
Describe the 3 leads of an ECG, the direction of each, and what each tracks
Lead I: Right arm (-) → Left arm (+)
Tracks electrical activity across the top of the heart (atria).
Lead II (most commonly used for heart rhythm): Right arm (-) → Left leg (+)
Shows overall heart rhythm and detects arrhythmias.
Lead III: Left arm (-) → Left leg (+)
Tracks activity from the bottom of the heart (ventricles).
Pulse oximetry requires light presented at what frequencies?
660 and 940
Photoplethysmography requires light presented at what frequencies?
540
Characteristics of a “Sick” PPG
dampened, delayed, or dimished
What might occur if a pacemaker’s sensitivity is set too low (not sensitive enough)?
It will ignore small intrinsic beats and overpace
What causes the PR interval to progressively lengthen in Wenckebach block?
Progressive AV node fatigue
