Defibrillator & cardioversion
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The document provides an overview of defibrillation and cardioversion in critical care, detailing their history, techniques, equipment, and indications for use. Defibrillation delivers non-synchronized shocks to treat life-threatening arrhythmias, while cardioversion uses synchronized shocks for less critical tachyarrhythmias. It also discusses waveform types, energy requirements, complications, and safety protocols for these emergency procedures.
![Indications
Indications for defibrillation include the following:
• Pulseless ventricular tachycardia (VT)
• Ventricular fibrillation (VF)
• Cardiac arrest due to or resulting in VF
Indications for electrical cardioversion include the following:
• Supraventricular tachycardia (atrioventricular nodal reentrant tachycardia
[AVNRT] and atrioventricular reentrant tachycardia [AVRT])
• Atrial fibrillation
• Atrial flutter (types I and II)
• Ventricular tachycardia with pulse
• Any patient with re-entrant tachycardia with narrow or wide QRS complex
(ventricular rate >150 bpm) who is unstable (e.g, ischemic chest pain, acute
pulmonary edema, hypotension, acute altered mental status, signs of shock)](https://image.slidesharecdn.com/defibcardioversion-180520112622/85/Defibrillator-cardioversion-9-320.jpg)
![Equipment
Equipment to be ready:
• Defibrillators (automated external defibrillators [AEDs], semi-automated
AEDs, standard defibrillators with monitors)
• Paddle or adhesive patch
• Conductive gel or paste
• ECG monitor with recorder
• Oxygen equipment
• Intubation kit
• Emergency pacing equipment
• Blood pressure cuff (automatic or manual)
• Pulse recorder
• Oxygen saturation monitor
• Intravenous access
• Suction device
• Code Cart with ACLS (Advanced Cardiovascular Life Support) medications](https://image.slidesharecdn.com/defibcardioversion-180520112622/85/Defibrillator-cardioversion-11-320.jpg)
![ECG strip shows SVT terminated by a synchronized shock
(synchronization marks [arrows] in the apex of the QRS complex) to
normal sinus rhythm.](https://image.slidesharecdn.com/defibcardioversion-180520112622/85/Defibrillator-cardioversion-17-320.jpg)
Defibrillator & cardioversion
- 1. Defibrillator & Cardioversion in Critical Care Dr Rajesh T Eapen Burjeel Hospital Muscat
- 2. Overview • Defibrillation is non-synchronized random administration of shock during a cardiac cycle. • In 1956, alternating current (AC) defibrillation was first introduced to treat ventricular fibrillation in humans. • Later in 1962, direct current (DC) defibrillation was introduced.
- 3. Cardioversion- What is it? • Cardioversion is a synchronized administration of shock during the R waves or QRS complex of a cardiac cycle.
- 4. History • 1849: Ludwigg and Hoffa – VF induced by electrical stimuli
- 5. History • 1899: Prevost and Batelli - while a weak stimulus can produce fibrillation, a stimulus of higher strength applied to the heart could arrest ventricular fibrillation and restore normal sinus rhythm.
- 6. History • 1947: First defibrillation on humans
- 7. History • 1966: Belfast Ambulance transport physicians performed first pre-hospital defibrillation. • 1969: First pre-hospital defibrillation by non physicians. • 1970’s: Diack, Wellborn and Rullman developed first AED’s.
- 8. How does it work? • During defibrillation and cardioversion, electrical current travels from the negative to the positive electrode by traversing myocardium. It causes all of the heart cells to contract simultaneously. This interrupts and terminates abnormal electrical rhythm. This, in turn, allows the sinus node to resume normal pacemaker activity.
- 9. Indications Indications for defibrillation include the following: • Pulseless ventricular tachycardia (VT) • Ventricular fibrillation (VF) • Cardiac arrest due to or resulting in VF Indications for electrical cardioversion include the following: • Supraventricular tachycardia (atrioventricular nodal reentrant tachycardia [AVNRT] and atrioventricular reentrant tachycardia [AVRT]) • Atrial fibrillation • Atrial flutter (types I and II) • Ventricular tachycardia with pulse • Any patient with re-entrant tachycardia with narrow or wide QRS complex (ventricular rate >150 bpm) who is unstable (e.g, ischemic chest pain, acute pulmonary edema, hypotension, acute altered mental status, signs of shock)
- 10. Anesthesia • Defibrillation is an emergent maneuver and, when necessary, should be promptly performed in conjunction with or prior to administration of induction or sedative agents. • Cardioversion is almost always performed under induction or sedation (short-acting agent such as midazolam). The only exceptions are if the patient is hemodynamically unstable or if cardiovascular collapse is imminent.
- 11. Equipment Equipment to be ready: • Defibrillators (automated external defibrillators [AEDs], semi-automated AEDs, standard defibrillators with monitors) • Paddle or adhesive patch • Conductive gel or paste • ECG monitor with recorder • Oxygen equipment • Intubation kit • Emergency pacing equipment • Blood pressure cuff (automatic or manual) • Pulse recorder • Oxygen saturation monitor • Intravenous access • Suction device • Code Cart with ACLS (Advanced Cardiovascular Life Support) medications
- 12. • The use of hand-held paddle electrodes may be more effective than self-adhesive patch electrodes. • The success rates are slightly higher for patients assigned to paddled electrodes because these hand-held electrodes improve electrode-to-skin contact and reduce the transthoracic impedance.
- 13. Positioning • Paddle placement on the chest wall has 2 conventional positions: anterolateral and anteroposterior. • In the anterolateral position, a single paddle is placed on the left fourth or fifth intercostal space on the mid axillary line. The second paddle is placed just to the right of the sternal edge on the second or third intercostal space. • In the anteroposterior position, a single paddle is placed to the right of the sternum, as above, and the other paddle is placed between the tip of the left scapula and the spine. • An anteroposterior electrode position is more effective than the anterolateral position for external cardioversion of persistent atrial fibrillation. • The anteroposterior approach is also preferred in patients with implantable devices, to avoid shunting current to the implantable device and damaging its system.
- 14. Technique • Emergent application, which may be life-saving, and elective cardioversion should be used cautiously, with attention to patient selection and proper techniques. Repetitive, futile attempts at direct current cardioversion should be avoided. • Advanced cardiovascular life support (ACLS) measures should be instituted in preparing the patient, such as obtaining intravenous access and preparing airway management equipment, sedative drugs, and a monitoring device. For elective procedures, prepare as follows: • Nil per os (NPO) for 8 hours prior to the procedure • Stop digoxin 48 hours prior to the procedure • Continue medications on the morning of the procedure under the direction of the physician • After the procedure, do not drive, operate machinery, or sign important documents for 24 hours and/or until sedation has worn off • There is no patient preparation for emergency procedures.
- 15. Monophasic versus biphasic waveforms • Defibrillators can deliver energy in various waveforms that are broadly characterized as monophasic or biphasic. • Monophasic defibrillation delivers a charge in only one direction. Biphasic defibrillation delivers a charge in one direction for half of the shock and in the electrically opposite direction for the second half. • Newer defibrillators deliver energy in biphasic waveforms. Biphasic waveform defibrillators deliver a more consistent magnitude of current. They tend to successfully terminate arrhythmias at lower energies than monophasic waveform defibrillators.
- 16. Energy selection for defibrillation or cardioversion • In 2010, the American Heart Association issued guidelines for initial energy requirements for monophasic and biphasic waveforms. Atrial fibrillation energy requirements are as follows: • 200 Joules for monophasic devices • 120-200 Joules for biphasic devices Atrial flutter energy requirements are as follows: • 100 Joules for monophasic devices • 50-100 Joules for biphasic devices Ventricular tachycardia with pulse energy requirements are as follows: • 200 Joules for monophasic devices • 100 Joules for biphasic devices Ventricular fibrillation or pulseless ventricular tachycardia energy requirements are as follows: • 360 Joules for monomorphic devices • 120-200 Joules for biphasic devices
- 17. ECG strip shows SVT terminated by a synchronized shock (synchronization marks [arrows] in the apex of the QRS complex) to normal sinus rhythm.
- 18. • Ventricular fibrillation terminated by an unsynchronized shock (arrows) to normal sinus rhythm.
- 19. Complications • The most common complications are harmless arrhythmias, such as atrial, ventricular, and junctional premature beats. • Serious complications include ventricular fibrillation (VF) resulting from high amounts of electrical energy, digitalis toxicity, severe heart disease, or improper synchronization of the shock with the R wave. • Thromboembolization is associated with cardioversion in 1-3% of patients, especially in patients with atrial fibrillation who have not been anticoagulated prior to cardioversion. Current American College of Cardiology (ACC)/American Heart Association (AHA) guidelines recommend to anticoagulate for 3-4 weeks before and after cardioversion. The presence of an intracardiac thrombus should be excluded using transesophageal echocardiography prior to cardioversion if therapeutic anticoagulation has not been achieved.
- 20. Manual - Internal • Same as manual external except pads are in direct contact with the heart Usually found operating rooms
- 21. Automated External (AED) • Uses computer to analyze heart then suggest whether a shock is needed or not • Usually found in public places • Made simpler for anyone to use
- 22. Implantable Cardioverter • Similar to pacemakers, constantly monitor patients heart and administer shocks when needed • Limitation – cannot distinguish when heartbeat changes due to exercise and other activities
- 24. 24 Sternum Apex
- 25. 25 Automated AED
- 26. Wearable Cardiac defibrillator • Portable defibrillator that is worn as a vest, monitors heart 24/7 • Not as common as others
- 27. 27
- 28. Cardioversion • Alive, unstable, tachyarrhythmia • Unstable? - Signs of low cardiac output: systolic hypotension < 90 mmHg, altered mental status - Excessive rates >150/min - Chest pain - Heart failure • Synchronized cardioversion is shock delivery that is timed (synchronized) with the QRS complex 28
- 29. Conditions Starting J (monophasic) AF 200 Atrial flutter 100 VT 200 SVT 100 29
- 30. 30
- 32. 32
- 33. Types of Cardioversion Chemical cardioversion • Antiarrhythmic medications are used to alter flow of electrical activity through the heart. Based on the clinical situation, chemical cardioversion can be performed in the hospital in monitored setting or in an outpatient setting. Electrical cardioversion • This is also known as direct current (DC) cardioversion. Electrical shock is synchronized (perfectly timed) to convert an abnormal rhythm to a normal sinus rhythm. DC cardioversion is performed in the hospital in a monitored setting. Internal cardioversion • Internal cardioversion is performed less frequently nowadays, owing to the presence of biphasic waveform defibrillators and intravenous ibutilide. It is performed if external cardioversion fails. It is performed using preexisting implantable cardioverter defibrillators (ICDs), epicardial wires during surgery, or internal paddles applied to the epicardium in the presence of sternotomy wires. Advantages of internal cardioversion are that this technique avoids the risk of a skin irritation from external shock. Disadvantages are that it may damage ICD systems, it consumes the battery of the ICD, and it does not always convert atrial arrhythmias.
- 34. Safety General Safety • Yourself, other staff – Dry surface area – Oxygen • Chest wall – Pads not touching
- 35. Safety Operator Safety • Assertive • Announce: – CHARGING, – ALL CLEAR / STAND CLEAR (Visual Check of Area), – SHOCKING • Check rhythm • Discharge Shock • Continue as per algorithm