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Cardiac EP Barry
Cardiac Electrophysiology Barry
| Question | Answer |
|---|---|
| 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. |
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