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Principles 2 Test 2
Implantable Cardiac Devices
| Question | Answer |
|---|---|
| What are the components of an implantable pacemaker? | pulse generator (power source or batteries), leads or wires, cathode (negative electrode), anode (positive electrode), body tissue |
| What is the difference between bipolar and unipolar? | bipolar = the body tissue is part of the circuit; unipolar = body tissue contact is essential for grounding |
| What is the pulse generator? | contains a battery that provides the energy for the electrical impulses and it houses the circuitry that controls the pacemaker |
| What parts of the pacemaker are located in the "hybrid" portion? | Reed switch, clock, output capacitors, defibrillation protection, and resistors |
| What parts of the pacemaker are located in the "connector" portion? | atrial and ventricular connectors |
| Leads are insulated wires that do what 2 things? | deliver electrical impulses from the pulse generator to the heart and sense cardiac depolarization |
| What are the 4 components of a pacing lead? | conductor, connector pin, insulation, electrode |
| When was the first pacemaker placed? | 1958 |
| When was the first ICD placed? | 1980 |
| What are 9 indications for a pacemaker? | Chronic AV heart block, chronic bifasicular and trifasicular block, AV heart block after acute MI, sinus node dysfunction, hypersensitive carotid sinus (neurogenic syncope), bradycardia, dilated cardiomyopathy, cardiac transplantation, tachydysrhythmias |
| How is an endocardial lead inserted? | intravenously |
| How is an epicardial or myocardial lead inserted? | subcostally |
| How is a transvenous lead inserted? | via a large vein |
| In a bipolar electrode configuration, where are the positive and negative leads placed? | both are placed in the chamber being paced |
| In a unipolar electrode configuration, where are the positive and negative leads placed? | the negative electrode placed in the atrium or ventricle and the positive electrode is placed outside the heart |
| What is rate adaptive pacing triggered by? | shortened QT interval, increase in RR or MV, increase in atrial rate, rise in CV temp, decrease in venous blood pH, increase in RV stroke volume, increase in ventricular pump action, increase in body movement |
| Are all pacemakers rate adaptive? | no |
| What are the indications for biventricular pacing? | moderate to severe CHF |
| What are 4 indications for an ICD? | cardiac arrest due to VT/Vfib, drug resistance VT with hemodynamic impact causing syncope, CAD with a hx of sudden death with documented VT, prevention for pts with CAD and non sustained VT |
| How do epicardial patches deliver shock? | they lay on top of the epicardium |
| What are the 3 main reasons you would have a cardiac device? | anti-tachycardia pacing, anti-bradycardia pacing, cardioversion and defibrillation |
| What symptoms that a patient with a pacemaker report to you in pre-op could indicate a problem with their device? | vertigo or syncope |
| If a patient tells you that their pacemaker is set to pace when their heart rate falls below 70, and when you check their pulse, their rate is in the 60's, what could this indicate? | battery failure or issue |
| What does placing a magnet over the pacemaker do? | activates the Reed switch, which puts the pacer into asynchronous mode, so it will pace regardless of what is sensed |
| What are some important things to determine about a patient with a pacemaker before surgery? | dependency on device, why it was placed, function of device, when it was last interrogated or when battery was last replaced |
| Does a device have to be interrogated before any and all surgical procedures? | no; only if you suspect and issue or the patient has NO idea about their device - interrogation not required often |
| What are 6 things you do to manage a patient with a device under anesthesia? | monitor EKG, monitor peripheral pulse (SaO2), Defibrillator present, have magnet available, have atropine epi and isoproterenol available, and be prepared for pacer failure |
| What is the most common source of electromagnetic interference in the OR? | electrocautery; others = AC power supplies, microwaves, ventilators, monitors, MRI, radiation therapy, peripheral nerve stimulators |
| What 3 things determine the electromagnetic interference effect on a device? | strength of the source, distance of the source from the leads and pulse generator, frequency of the signal |
| What kind of response can a pacemaker have to electromagnetic interference (EMI)? | inhibition r/t ventricular over-sensing, pacing asynchronously, triggering atrial or ventricular fibrillation, burning myocardium at lead site, energy can damage pulse generator or battery or reprogram it |
| What kind of response can a defibrillator have to electromagnetic interference (EMI)? | inappropriate shock delivery, failure to deliver shock, reprogramming, burning myocardium at lead site, energy damages battery/pulse generator |
| Which is better at reducing EMI, bipolar cautery, unipolar cautery, or harmonic scalpel? | bipolar cautery or harmonic scalpel |
| If defibrillation is necessary in a patient with a device, what is the best way to go about it? | anterior-posterior placement of paddles/pads and lowest effective dose of energy possible |
| What is the magnet rate? | 70 - 72 paces/minute |
| Why should the prudent CRNA ensure that the magnet mat is not placed on or near the chest in a patient with a cardiac device? | it can activate the reed switch |
| What does the magnet do if placed over an ICD(defibrillator)? | disables detection of tachydysrhythmias, thus no shock can be delivered, but pacing ability remains intact |
| When a magnet is removed from placement over an ICD (defibrillator) what happens? | it varies, some reactivate while others remain inactivated and must be reset which is indicated by a beep |
| In terms of pacemaker code, what is meant by a device that is labeled VVI? | ventricle is paced, ventricle is sensed, and the response it has is inhibitory; "ventricular demand pacing" |
| In terms of pacemaker code, what is meant by a device that is labeled AAI? | atrium is paced, atrium is sensed, and the response it has is inhibitory; "atrial demand pacing" |
| In terms of pacemaker code, what is meant by a device labeled VAT? | ventricle is paced, atrium is sensed, and the response is that it is triggered; "atrial synchronized pacing" |
| In terms of pacemaker code, what is meant by a device labeled VDD? | ventricle is paced, both atrium and ventricle are sensed, and the response is both trigger and inhibition; "atrial synchronized, ventricular inhibited" |
| In terms of pacemaker code, what is meant by a device labeled DVI? | atrium and ventricles are paced, ventricle is sensed, and the response is inhibitory; "A-V Sequential" |
| In terms of pacemaker code, what is meant by a device labeled DDD? | atrium and ventricles are paced, atrium and ventricles are sensed, and the response is both trigger and inhibition; "A-V Universal" |
| For deciphering pacemaker code, what does the first letter (I) indicate? | chamber paced |
| For deciphering pacemaker code, what does the second letter (II) indicate? | chamber sensed |
| For deciphering pacemaker code, what does the third letter (III) indicate? | response to sensing |
| For deciphering pacemaker code, what does the fourth letter (IV) indicate? | programmable functions/rate modulation |
| For deciphering pacemaker code, what does the fifth letter (V) indicate? | anti-tachydysrhythmias function(s) |
Created by:
Mary Beth
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