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Cardiac EP Barry

Cardiac Electrophysiology Barry

QuestionAnswer
What are indications for pacing? - AV heart block: 2nd degree type II and 3rd degree heart block. -Symptomatic bradycardia. -AV heart block =MI -Heart block post MAZE procedure. -Chronic bifascicular or trifascicular block. -Sinus node dysfunction (sick sinus syndrome).
How long does a pacer battery last? 5-8 years.
What do pacer leads do? Connect power source and electronic circuitry to electrodes.
What do pacer electrodes do? Used for cardiac sensing and stimulation.
Describe unipolar pacer: One electrode at distal tip of lead (neg), Positive pole is in the generator.
Describe bipolar pacer: Two electrodes located on the lead. Provides smaller, more selective sensing area thus less oversensing potential. Small pacer spike.
Epicardial leads: where, when, what for? Epicardial leads are placed directly on the heart during cardiac surgery or for biventricular pacing.
Endocardial leads: where, what for? Placed transvenous for temp or perm pacing.
Two kinds of direct cardiac pacing: Epicardial and endocardial.
Two kinds of indirect cardiac pacing: 1. Trancutaneous pacing with pacer pads. 2. Transesophageal pacing with electrodes positioned behind the left atrium or ventricle in the esophagus.
ICHD: Inter-society Commission for Heart Disease.
Pacing 1st position: 1st position designates chamber paced. A= atrium, V= ventricle, D= dual.
Pacing 2nd position: 2nd position designates chamber sensed. A=atrium, V=ventricle, D=dual, O=none.
Pacing 3rd position: 3rd position designates response to sensed events. I=inhibited, T=triggered, D=double (both I and T), or O=none.
Pacing 4th and 5th positions: 4th and 5th positions designated programmable and special antitachycardia functions.
Single chamber pacing modes: Asynchronous (fixed rate pacing) Pacer delivers stimuli at a programmed rate without regard to patients intrinsic rhythm. ie: AOO, VOO.
Asynchronous pacing is mostly used with... Temporary pacers.
Asynchronous pacing can interfere with patient's intrinsic rhythm and can induce... Tachydysrhythmias.
Noncompetitive (demand) pacers sense and respond to... Intrinsic atrial or ventricular myopotentials.
In noncompetitive (demand) pacing, the response to a sensed myopotential will be... Inhibition of pacemaker output in one or the other chamber. ie: VVI, AAI.
VVI: Used in... A-fib. Most common pacing mode. Magnet will convert to fixed rate usually .
What is the most common pacing mode? VVI.
AAI: Used in... Sinus node dysfunction with an intact AV conduction.
Dual chamber pacing mode is intended to... Preserve a more normal relationship between atrial and ventricular contractions.
Dual chamber pacing mode provides AV... Synchrony.
How does dual chamber pacing mode affect chance of AF? Lowers incidence of AF.
Dual chamber pacing mode lowers risk of systemic embolism and... Stroke.
CHF and dual chamber pacing? Decreases incidence of CHF.
Dual chamber pacing and mortality? Decreases mortality.
True or false. Dual chamber pacing reduces LV filling. False. Dual chamber pacing increases LV filling.
By how much does dual chamber pacing increase CO? 30-40%.
Dual chamber pacing and regurg? Reduces incidence of mitral and tricuspid regurg.
High tech pacing functions: Pts with prolonged QT intervals can be cont paced to... Prevent Torsades.
How do you use pacing to prevent Torsades? Continuously pace patients with prolonged QT intervals.
Terminating tachyarrhythmia: Reentrant rhythms like aflutter, PAT and VT can be terminated by... A variety of pacing patterns.
Rate responsive pacers. Clinically benefits patients by restoring a physiological HR during physical activity. How? Based on muscle activity and resp rate. Detects states of exercise and triggers accelerations in pacing rate to meet the needs of the patient.
DDD pacers will sometimes track atrial activity to a max track in paroxysmal atrial flutter. This will cause a undesirable acceleration in ventricular pacing rate. Automatic mode switching will... Detect these nonphysiological atrial rates and automatically switch to a non atrial tracking mode.
Biventricular pacing is used in whom? Why? Patients with decreased ejection fraction. Delay in contraction between right and left side decreases heart filling time and thus total CO.
In biventricular pacing, what three leads are used? 1. Right atrial lead 2. Right ventricular lead 3. Left ventricular lead
In biventricular pacing, how is the LV lead placed? LV lead is passed from the right atrium into the coronary sinus vein and is placed in a vein on the lateral wall of the left ventricle.
Biventricular pacing causes synchronous contraction between left and right side of the heart. What does this do to mitral flow? Reduces mitral regurgitation and allows for a better forward flow.
How does biventricular pacing reduce mitral regurg and allow for better flow? Biventricular pacing causes synchronous contraction between left and right side of the heart.
Biventricular pacing causes synchronous contraction between left and right side of the heart. What does this do to the septal wall? Decreases the dyskinetic motion of the septal wall which can affect forward flow.
Can biventricular pacing be combined with ICD? Yes.
Anesthetically, how are biventricular pacers placed? Placed transvenous under MAC.
Failure to output: No pacing spike is present despite an indication to pace. Troubleshoot (5 things). -May be due to battery failure -Lead fracture -Oversensing: shivering, muscle contractions, fasiculations, cautery -Crosstalk: Atrial output is sensed by the ventricular lead -Poor lead contact
How to correct failure to output (no pacing spike is present despite an indication to pace) which is being caused by cautery? Use bipolar which restricts the energy field to areas around the cautery probe.
Failure to capture. Occurs when a pacing spike is not followed by either an atrial or a ventricular complex. Troubleshoot (6 things). -Lead fracture -Lead dislodgement -Elevated pacing threshold -MI -Vfib -Metabolic abnormalities (hyperkalemia, acidosis)
Oversensing. Occurs when, and is caused by what? Occurs when a pacer incorrectly senses electrical activity and is inhibited from correctly pacing. Muscular activity, electronagnetic interference.
Failure to sense: undersensing. Pacer paces inappropriately. Does not recognize intrinisic rhythm. Fix the problem. Sensitivity needs to be adjusted. Give the pacer more brain power.
Undersensing. Occurs when a pacer incorrectly misses intrinsic depolarization and paces despite intrinsic activity. Four causes? 1. Poor lead positioning 2. Lead dislodgment 3. Magnet application 4. Low battery
Temp. transvenous or epicardial pacing: Epicardial leads to temp pacer post heart surgery.
mA=Output: Allows for adjustment of the stimulus current. Measured in mA from .1-20. Adjust according to current needed to elicit myocardial depolarization.
Sensitivity= Brain power. Detects pts intrinsic rhythm or lack of. The lowest number (blank) the pacer is the smartest. The highest number (blank) the pacer is brainless=asynchronous mode. 1.0 mV, 20 mV
Temp pulse generators can (blank), (blank), or (blank) pace. A, V, dual.
Transcutaneous pacer pad placement (2 ways): External Pacing pads: Ant-Post= Sandwich the heart. Ant placement= Do not place on bony area (sternum).
Six steps of transcutaneous pacing: 1.Place EKG leads on 2.Turn monitor on 3.Choose rate 4.Demand or Asynchronous mA usually around 100 can go up to 200 5.Start 6.Assess patient
How many deaths due to VF? Approx 250,000 deaths due to VF.
AICD implanted in high risk population Successfully terminates VF in (blank) of episodes Over 98%.
What does ICD stand for? Implantable cardioverter-defibrillator.
Most BiV pacers also have a (blank) mode. ICD.
What does an ICD do in the case of VT? Detects and attempts to override pace VT. If unable to override pace it will defib pt.
An ICD will defib. VF after (blank) seconds at (blank) J. Subsequent shocks will be delivered every (blank) seconds. 10-30 seconds, 20-30 J, 10-30 seconds.
Why does the AICD need to be deactivated preop by rep? EMI (electromagnetic interference) from cautery can elicit a shock.
After the rep. deactivates the AICD, what do you need to do next? Transcutaneous pacing/defib pads need to be placed on pt.
How do you use a magnet on Medtronic and St. Jude? Magnet stays on generator to deactivate it. Take it off to reactivate.
How do you use a magnet on Guidant? Magnet over it for 30 seconds until continuous tone is heard to deactivate. Magnet back on beeping synch with R wave for reactivation.
AICD's are placed under MAC, similar to pacers. Usually tested with three shocks. Two important management facts? 1.Do not use antiarrhythmics. 2.Have transcutaneous pacer/defib on patient.
VT drugs excepting Amiodarone. Lido 1mg/kg Q 3-5 min total 3mg/kg Pronestyl 17 mg/kg (20mg/min) new changes Vasopressin 40 units ( May replace 1st or 2nd dose of epi) Epi 1mg Q 3 min Mg sulfate 1-2 gms IV for torsades
Amiodarone doses for VT: pulse vs pulseless. Amiodarone VT with pulse=150mg over 10 mins repeat in 10mins then infusion. Pulseless=300mg IV X1 May repeat 2nd dose at 150mg
Treatment for VF: -Check Pulse -Shock @ 360 J (monophasic) or 120-200J (biphasic) x1 -ACLS -CPR 30 : 2 EARLY DEFIB and GREAT CPR saves lives !!!!
Cardiac mapping is used to... Dx arrhythmias by locating small area of abnormal heart tissue.
How does cardiac mapping diagnose arrythmias? Electrodes placed in heart record the pathway of electrical signals.
What is an IABP? What does it do? A volume displacement device designed to provide partial assistance to the left ventricle by inflation and deflation of an intraaortic balloon catheter synchronized with the cardiac cycle.
IABP is used in myocardial conditions where medical therapy is inadequate to support the left ventricle. Four examples: 1. Left ventricular failure 2. Failure to wean from CPB 3. Unstable angina 4. Bridge to heart transplant
Four contraindications to IABP. 1. Aortic regurgitation 2. Severe peripheral vascular disease 3. Blood dyscrasias 4. Aortic dissection
When does IABP inflate? Balloon inflation occurs at the same time that the aortic valve closes (Dicrotic notch).
During diastole IABP benefits coronary perfusion in two ways: 1. Inflated balloon augments diastolic pressure. 2. Blood volume in the aorta is displaced by the inflated balloon toward the coronary arteries.
When does IABP deflate? Deflation occurs just prior to the next systole. (timing on the R wave or upstroke on arterial wave form).
What happens during IABP deflation? For a few milliseconds after the balloon is deflated, the left ventricle has less pressure to eject against= decrease afterload.
Created by: 1592042303