Circulatory Assist Devices: Countershock & Nursing

• This info is for Circulatory Assist Devices
• This contains information for Countershock, Pacemakers, ICD, and hypothermia
• The key topics are indications & interventions for countershock, as well as nursing roles

Indications

• Correct dysrhythmias
• Example: A-fib

Cardioversion - Purpose

• Cardioversion uses electrical currents to convert dysrhythmias
• Examples: Atrial Fibrillation, SVT
• Effective dysrhythmia treatment requires an R wave (or QS wave) that the machine can recognize and "sync" with
• Symptoms may include hypotension, dyspnea, and chest pain

A-Fib treatment

• If the duration is less than 48 hours: Use digitalis, calcium channel blockers, beta-blockers, amiodarone, or cardioversion
• If duration is more than 48 hours, and treatment is non-emergent: Anticoagulation for 2-3 weeks, then cardioversion
• If duration is more than 48 hours, and treatment is in emergencies: Heparin, transesophageal echocardiogram to rule out atrial clots, then cardioversion

Protocols

• Procedural sedation involves Etomidate and Fentanyl
• These are hypnotic sedatives and narcotic analgesics
• Defibrillator pads placement include anterior-posterior, which works best with A-fib
• Press the "sync" button on the defibrillator
• Initial dose is normally 100-120 joules of biphasic current, and may repeat with 200 joules

Nursing Considerations

• Patient needs to provide Informed consent
• Team should be present: MD, RN, RT, RPh
• RN should ensure meds are given
• IV access is patent
• ECG strips are documented before and after the procedure
• O2 and metal removed from patient
• Look for indicators that the machine is "synching" with R waves

Countershock/Defibrillation

• An unsynchronized electric shock usually administers a larger number of joules than cardioversion
• It is unsynchronized, because there is no discernable "R" wave to sync the machine with
• Examples: Ventricular fibrillation and ventricular tachycardia when a patient is pulseless
• Signals are sent to the heart to depolarize
• Generally used to maintain a reasonable heart rate in a patient whose own heart rate is too slow
• It can pace the atrium, ventricle, or both
• Use when myocardial conduction cannot maintain adequate cardiac output when myocardial conduction is being maintained
• In addition to drug therapy, pacemakers are used when the heart's own conduction system fails or is incapable of maintaining enough stimulus to create an adequate cardiac output
• Pacemakers are used in addition to drug therapy when one of three conditions exists: failure of the conduction system, failure to initiate an impulse spontaneously, or failure to maintain primary pacing control
• Pacemakers are relatively new to being used in treatment of heart failure

Components of pacemakers

• Internal pulse generator, which is typically located in a subcutaneous tissue pocket
• This is typically above the muscles and ribs, below the clavicle in the chest wall
• The leads are passed transvenously into the heart and rest on the endocardium
• Endocardial pacers are usually inserted through the subclavian or jugular veins into the atria and/or, ventricle(s), where they are lodged
• The generator is a small, thin, sealed device that contains a battery and is programmed according to the needs of the patient

Temporary Pacemakers

• External Pacemakers: Delivers electric impulses to the myocardium transcutaneously through two electrode pads
• The pads placed anteriorly or anteriorly and posteriorly on the chest
• Epicardial Pacemakers: Used during open heart surgery procedures
• Has wires that can be attached directly to the atria for atrial pacing and/or the ventricles for ventricular pacing post-open heart surgery
• Transvenous Pacemakers: Achieved through electrical stimulation of the right ventricular or right atrial endocardium by an electrode-tipped catheter
• Approaches for pacing wire placement include direct insertion and insertion of a special pulmonary artery catheter
• Both approaches use a central vein, often the subclavian or internal jugular, for insertion

Firing, Capture, and Sensing

• Firing: When the heart rate drops below that set rate, the pacemaker generates, and fires an electrical impulse that then passes through the lead to the heart muscle causing a heartbeat
• Capture: Initiation of depolarization of the atria and/or ventricles by an electrical stimulus delivered by an artificial pacemaker seen as a spike
• Used to describe in situations where the pacemaker initiates an impulse, but the stimulus is not strong enough to produce depolarization
• A pacing spike is present, but P waves or QRS complexes or both are absent
• Sensing: The ability of the pacemaker to detect the heart's intrinsic electrical activity -Failure to sense is the term used if the pacemaker competes with the patient's own impulse generation

Pacemaker Codes

• First letter: Chamber that is paced
• A = atria
• V = ventricles
• D = dual-chamber
• Second letter: Chamber that is sensed
• A = atria
• V = ventricles
• D = dual-chamber
• 0 = none
• Third letter: Response to a sensed event
  • T = triggered
  • I = inhibited
  • D = dual
  • T and I, R = reverse
• For example: A DDD pacemaker is a dual-chamber pacemaker that is able to pace and sense both the atria and ventricle(s)

Pacemaker Rhythms

• Pacemaker rhythms come in VVI or DDD
• DDD paces and senses the atria and ventricles
• VVI paces and senses the Ventricle

Pacemaker Malfunctions

• Failure to fire: Occurs when a pacemaker fails to send out an electrical impulse at the appointed time
• Common causes are a loose pacemaker wire connection and a dead pacemaker battery
• Lack of a visible pacemaker spike followed by a pause will be noted on the cardiac monitor
• Failure to fire can be intermittent or sustained, and if sustained, the ECG will show a reversion to the patient's underlying rhythm
• Loss of capture: Describes when the pacemaker initiates an impulse, but the stimulus is not strong enough to produce depolarization
• A pacing spike is present, but P waves or QRS complexes or both are absent
• For appropriate sensing and capturing, the pulse generator has adequate battery function
• The leads must be firmly attached to the pacemaker and the endocardium
• Must have lead wires intact with a high enough mA output
• Undersensing: Describes when the pacemaker competes with the patient's own impulse generation
• A potentially dangerous situation because the pacemaker can discharge an impulse during the relative refractory or supranormal periods of ventricular repolarization, precipitating ventricular fibrillation

ICD function

• Key function includes placement in patients who have had prior aborted sudden cardiac death or proven sustained ventricular tachycardia
• Also in high-risk groups with forms of cardiomyopathy
• It is fully implantable with battery-operated device intended to recognize and terminate ventricular tachyarrhythmias
• ICDs are capable of distinguishing ventricular tachycardia (VT) from ventricular fibrillation (VF) providing defibrillation shocks when necessary
• Antitachycardia pacing treats VT without cardioversion shocks
• Backup bradycardia pacing eliminates the need for a standard pacemaker, and provides cardiac event storage for retrieved patient responses to treatment

Nursing responsibilities with cardioversion and defibrillation

• Obtaining Informed consent
• Having the team present: MD, RN, RT, RPh
• Ensuring meds are given
• Ensuring IV access is patent
• Documenting ECG strips before and after the procedure
• Removing O2 and metal from patient

indications for ICDs

• prevents sudden cardiac death
• prevents sustained VT
• helps to and terminate dangerous shocks
• monitors the heart’s electrical activity
• The site of a small electronic devices monitor heart rhythm and deliver electric shocks when necessary to treat life-threatening arrhythmias and prevent cardiac arrest

nursing implications for ICD patient

• Review the nursing responsibilities with cardioversion and defibrillation
• Look for indicators that machine is ‘synching’ with R waves
• ECG pattern should be monitored to determine if the pacemaker is pacing at the correct rate, capturing with each impulse, and sensing the patient's own rhythm.
• Assess if the nurse is assessing the threshold and minimal amount of output required to initiate depolarization of the pacemaker

Key concepts when teaching about ICDs

• Provide literature device
• Involve devices the correct method of checking
• Patients with dysrhythmias can show you their most recent ECG's
• Bracelets showing pacemakers or ICDs and model number and should be readily available patient

Hypothermia effects

• The lack of blood flow can cause lasting damage to the brain
• The person may be unable to regain consciousness
• It lowers the body temperature helping to body temperature damage after a cardiac arrest and raises chances the person will recover.

Nursing during cooling process

• Cool patients 90-93 degrees Fahrenheit with External cooling pads and blankets or ice cold Saline IV
• It protects The brain by slowing it down for function, but may cause atrial and ventricular dysrhythmia due to prolonging PR, QRS and QT
• Watch patients with sinus tachycardia by initiating therapy that turns to sinus bradycardia
• Watch Hypokalemia and give IV supplement

Rewarming patients

• Follow electrolyte shifts, pointy T waves, and rewinded, QRS
• Rewarming can cause vessels needing more space, vasodilation, hypotension rapid electrolyte, and monitor with a central venous pressure catheter

Cardiac Assist Device Types

• Countershock makes use of electrical current delivered to the heart to reset it with cardioversion and defibrillation

Electrical

• Countershock that delivers an electric current is synchronized, in contrast with Unsynchronized electrical shocks administration with joules, also known as Defibrillation where there is no discernable R wave to sync with
• Electrical shocks are used for Ventricular is not responsive to medication or if there is atrial fibrillation, flutter and ventricular tachycardia with unstable parameters

Interventions

• Once attached, "sync" will be pushed.
• Make sure it coincides with the R wave
• Machine discharges after the R wake Conductive paste will be put on the chest wall and base
• This can be seen on with Automatic Defibrillator and used by Medical and lay personals

Patient Nursing

• Monitor electrolyte imbalance like calcium magnesium and potassium, conductive pads, place them on the right side beneath the right clavicle and and Midaxillary line on the other side.
• Do know to let nurses know to let people know before that equipment or the patient not touchness bed the electricity is on, inform, and doctor of imbalance and have all metals and objects be removed"

Major Coronary Artery Blood Flow Patterns

• Anterior wall patterns originate and are fed by the front side, as opposed to Bottom or right side wall which relates to Inferior portion
• Latteral portion is supplied by the left side wall, or Posterior which is the back Wall
• LAD artery and coronary artery has a main portion that connects to the the wall
• Circumflex has a lateral wall