Cardioversion and Atrial Fibrillation Treatment

• Cardioversion converts dysrhythmias using electrical current.
• Examples include atrial fibrillation and supraventricular tachycardia
• Dysrhythmia must have an R wave (or QS wave) for the machine to "sync" with.
• Patient symptoms may include hypotension, dyspnea, and chest pain.

Atrial Fibrillation Treatment

• If the duration is less than 48 hours, treatments include digitalis, calcium channel blockers, beta-blockers, amiodarone, or cardioversion.
• If the duration is more than 48 hours and non-emergent, anticoagulation is needed for 2-3 weeks before cardioversion.
• In emergencies, heparin and a transesophageal echocardiogram should be conducted before cardioversion, to rule out atrial clots.

Protocols for Countershock/Cardioversion

• Procedural sedation involves hypnotic sedatives and narcotic analgesics like Etomidate and Fentanyl.
• Anterior-posterior placement of defibrillator pads works best for atrial fibrillation.
• The "sync" button has to be pressed on the defibrillator (SEE TEXT for why)
• The starting dose of current is 100-120 joules of biphasic current and may be repeated with 200 joules.

Nursing Considerations

• Informed consent must be obtained.
• A team should be present, including an MD, RN, RT, and RPh.
• The registered nurse (RN) ensures medications are administered.
• IV access has to be patent
• ECG strips are documented before and after the procedure.
• Remove oxygen and metal from the patient

Indicators of Synchronizing with R Waves

• Look for indicators that the machine is "synching" with R waves.
• The machine marks each detected R wave during synchronization.

Countershock/Defibrillation

• An unsynchronized electric shock usually gives a larger number of joules than cardioversion
• It is unsynchronized because there is no discernible "R" wave to sync the machine with.
• Examples include ventricular fibrillation and ventricular tachycardia when the patient is pulseless.

Adult Cardiac Arrest

• Call for help and activate the emergency response system.
• Start CPR by giving oxygen, and attach a monitor/defibrillator.
• Check the rhythm.
• If there is ventricular fibrillation (VF) or ventricular tachycardia (VT), administer a shock.
• Give epinephrine every 3-5 minutes and amiodarone for refractory VF/VT through IV/IO access.
• Consider advanced airway and quantitative waveform capnography.
• Treat reversible causes.
• Monitor CPR quality.
• Return of spontaneous circulation involves assessing the pulse and blood pressure.
• There should be an abrupt sustained increase in PETCO2 (typically ≥40 mm Hg)
• Spontaneous arterial pressure waves with intra-arterial monitoring should be observed.

CPR Quality

• Push hard (≥2 inches [5 cm]) and fast (≥100/min)
• Allow complete chest recoil
• Minimize interruptions in compressions
• Avoid excessive ventilation
• Rotate compressor every 2 minutes
• Use a 30:2 compression-ventilation ratio if no advanced airway present
• Attempt to improve CPR quality if PETCO2 <10 mm Hg
• Attempt to improve CPR quality if relaxation phase (diastolic) pressure <20 mm Hg

Shock Energy

• Use manufacturer recommendation for biphasic shock. (e.g., initial dose of 120-200 J)
• Use the maximum available dose if the manufacturer recommendation is unknown.
• Second and subsequent doses should be equivalent, and higher doses may be considered.
• Monophasic shock is generally given at 360 J.

Drug Therapy for Cardiac Arrest

• Epinephrine IV/IO Dose: 1 mg every 3-5 minutes
• Vasopressin IV/IO Dose: 40 units can replace the first or second dose of epinephrine
• Amiodarone IV/IO Dose: First dose: 300 mg bolus. Second dose: 150 mg

Advanced Airway

• Use supraglottic advanced airway or endotracheal intubation
• Use waveform capnography to confirm and monitor endotracheal tube placement
• Administer 8-10 breaths per minute with continuous chest compressions

Reversible Causes of Cardiac Arrest

• Hypovolemia
• Hypoxia
• Hydrogen ion (acidosis)
• Hypo-/hyperkalemia
• Hypothermia
• Tension pneumothorax
• Tamponade, cardiac
• Toxins
• Thrombosis, pulmonary
• Thrombosis, coronary

Pacemakers

• A pulse generator provides an electrical stimulus to the heart.
• Pacemakers treat myocardial conduction that cannot maintain adequate cardiac output.
• The pulse generator connects to wires that carry the electrical stimulus to the myocardial cells.
• Pacemakers are used in addition to drug therapy
• Pacing mechanism can be temporary or permanent

Permanent Implanted Pacemakers

• Use an internal pulse generator and endocardial pacing.
• Implanted in the chest

Types of Pacing

• Programmed to pace different areas of the heart
• Most common types are designed to pace ventricles.
• Pacing will produce a spike before QRS complex.
• They are used when transmission of atrial impulses is blocked.
• It's programmed to pace when an intrinsic beat is not sensed.
• It initiates an impulse on sensing electrical activity.