Makindo Medical Notes

Related Subjects: |AF - General |AF and Anticoagulation |AF and Rate Control |AF and Rhythm Control and Cardioversion |AF ECG |DC cardioversion

Caution: compromise purely due to AF is rare. Compromise is more frequently due to the underlying condition, which must be treated first: e.g. Pneumonia, Sepsis causing hypotension, chronic LV dysfunction, AMI causing chest pain, PE. If unsure that the fast AF is the primary problem, seek senior advice.

About

• All unstable tachyarrhythmias should be considered for DC cardioversion
• IF AF and unstable/compromised DC cardiovert. Start anticoagulation
• Compromise = SBP < 90 mmHg, angina, pulmonary oedema
• Synchronization avoids the delivery of a shock during cardiac repolarization
• Shock on T wave can precipitate VF (which is shocked)

Indications for Emergency DC cardioversion

• Any tachyarrhythmia with compromise
• Fast AF causing haemodynamic compromise with low BP, angina, heart failure. Usually the HR is over 150/min despite Amiodarone or Digoxin or Beta Blocker
• SVT with causing haemodynamic compromise failed with Adenosine and/or Verapamil. Usually the HR is over 150/min Fast AF with preexcitation
• Suspected VT causing haemodynamic compromise

Indications for Elective DC cardioversion

• Elective for AF rhythm control strategy
• Elective for Atrial flutter
• Ensure all have had adequate anticoagulation in the past 3-4 weeks

Reasons not to Elective DC cardioversion

• AF duration more than a year
• Left atrium > 5 cm and atrial volume > 40 ml
• Failure of previous cardioversion despite adequate antiarrhythmics
• Not adequately anticoagulated
• Untreated infection, thyrotoxicosis, alcoholism, pericarditis, mitral valve disease

Anticoagulation

• Elective: The risk of cerebral embolism can be markedly reduced by anti-coagulation; patients who have been in AF for more than 24 h (some say 48 h)should be adequately anti-coagulated (INR >2) for a minimum of 3 weeks before and 4 weeks after elective cardioversion. This can be with warfarin, DOAC or full LMWH.
• Emergency: If AF > 48 hrs and not anticoagulated then there are concerns of embolism with DCC and so a TEE/TOE is recommended to look for clot in the left atrium. If clot is present or TEE/TOE cannot be done then take senior advice as the DCC may be lifesaving. All need formal anti-coagulation for 4 weeks of warfarin or DOAC or LMWH post procedure.

Steps

• Senior Dr to review need. Discuss with the cardiology team. Consent patient.
• Procedural sedation (RSI not usually required) dependent on user experience and local policy
• Call anaesthetist to assist with sedation and airway and monitoring
• Place Anteroposterior pad positions
• Synchronise the defibrillator to R wave for each shock
• Ensure the safety of environment prior to cardioversion
• Nobody touching the patient
• Nobody touching equipment that is touching the patient
• Consider removing supplemental oxygen
• Synchronised DC shock: 200 J 360 J you might have to hold down the button to await the R wave
• Consider Amiodarone infusion if resistant to 2nd shock
• Admit cardiology bed

Tachycardia with pulse and energy

• Narrow regular (SVT or Regular Atrial flutter): 50-100 J
• Narrow irregular (A fib ) Biphasic: 120-200 J or Monophasic: 200 J
• Wide regular (VT with pulse): 100 J
• Wide irregular: defibrillate (NOT synchronized)

Complications

• A less than 1% chance of having a stroke but reduce by ensuring anticoagulated
• A small risk of your heart rate going too slowly after the procedure
• A small burn on your chest and back where the sticky pads are placed, a bit like having sunburn
• Muscle aches across the chest and back where the muscles contract when we deliver the shock
• There is also a small risk of complications from the general anaesthetic/sedation

Investigations

• FBC, U&E, TFTs, CRP, CXR, INR
• 12 lead ECG
• Trans oesophageal Echo for those not anticoagulated with AF > 48 hrs who need DCC

References

• Synchronised DC Cardioversion