Journal of Obstetric Anaesthesia and Critical Care

CASE REPORT
Year
: 2021  |  Volume : 11  |  Issue : 1  |  Page : 33--35

Development of fast atrial fibrillation in an awake parturient undergoing elective caesarean section


Gregg James Baxter 
 Department of Anaesthesia, Countess of Chester Hospital, Liverpool Road, Chester, England

Correspondence Address:
Dr. Gregg James Baxter
Department of Anaesthesia, Countess of Chester Hospital, Liverpool Road, Chester CH2 1UL
England

Abstract

A 25 year-old, fit and well, G2P1 woman presented for elective caesarean section under spinal anaesthesia for breech presentation. Following a straight forward spinal anaesthetic and initial progression of surgery, the patient developed atrial fibrillation with a fast ventricular response shortly after delivery and bolus of 5 units of oxytocin. Attempts to restore sinus rhythm with pharmacological methods were unsuccessful and ultimately the patient required electrical cardioversion. An RSI was performed as the patient was still within the first 48 hours post-delivery. Upon laryngoscopy, the patient reverted to sinus rhythm without the need for DC cardioversion. After a short stay in the hospital, the patient was discharged with outpatient ECHO and follow-up awaited. Blood, including thyroid function tests, were unremarkable pre-, intra- and post-operatively. This case report highlights the rarity of development of AF whilst also covering the management of this arrhythmia in the context of the awake parturient.



How to cite this article:
Baxter GJ. Development of fast atrial fibrillation in an awake parturient undergoing elective caesarean section.J Obstet Anaesth Crit Care 2021;11:33-35


How to cite this URL:
Baxter GJ. Development of fast atrial fibrillation in an awake parturient undergoing elective caesarean section. J Obstet Anaesth Crit Care [serial online] 2021 [cited 2021 Jul 23 ];11:33-35
Available from: https://www.joacc.com/text.asp?2021/11/1/33/313911


Full Text



 Introduction



Atrial fibrillation is an arrhythmia characterised by the irregular beating of the atria of the heart. It shares links with many cardiovascular diseases but can also occur in otherwise healthy hearts. Thankfully, new-onset atrial fibrillation is rare during pregnancy and even rarer around the time of caesarean section. One study determined the incidence of AF in the setting of caesarean sections to be 0.04%.[1] Of the 7 people out of over 17,000 who developed AF in this study, all 7 developed the arrhythmia post-operatively.

AF is one of several disorders that falls under the umbrella term supraventricular tachycardia (SVT). Pregnancy predisposes patients to developing SVT through the physiological and hormonal changes that occur intrapartum.[2]

 Case



An otherwise healthy 25-year-old patient presented for elective caesarean section for breech presentation. She was G2P1 with one previous normal vaginal delivery. Her second pregnancy had been complicated by an admission to hospital for several days with Influenza A at 27 weeks gestation but had otherwise passed without incident. ECG at the time of admission with flu showed the patient to have a sinus tachycardia.

Monitoring of the patient was consistent with AAGBI guidelines and anaesthesia was established via the spinal technique using 2.6 mls of 0.5% heavy bupivacaine and 15 mcg of fentanyl. Heart rate in the initial period varied between 70 and 80 beats per minute with sinus rhythm displayed on our monitor. Block height to cold at 10 minutes was at the level of T4. Surgery was commenced without issue and a healthy baby was delivered shortly after. Five units of oxytocin was given intravenously, as a bolus, immediately after delivery of the baby. Over the next 1-2 minutes, the patient developed a tachycardia with the heart rate plateauing between 180-200 bpm [Figure 1]. Whilst maternal heart rate can rise upon the birth of their child, the rapidity of the rate and its prolonged nature alerted us to the fact that the patient had developed a tachyarrhythmia.{Figure 1}

Initial management followed the ABC algorithm. The patient remained conscious and reported no shortness of breath, chest pain, cough or palpitations. Because there were no adverse features of the tachycardia, we attempted non-pharmacological methods to try and cardiovert the patient. Unfortunately, Valsalva manoeuvre and carotid massage did nothing to reduce the ventricular rate. Feeling that paroxysmal SVT was the most likely diagnosis given the appearance of the rhythm on monitoring, Adenosine 6 mg and then 12 mg were given intravenously. Neither dose had a significant impact on the heart rate. Atenolol 2.5 mg was given and this brought her rate down to about 150 bpm and revealed a clearly irregular ECG [Figure 2]. After discussion with the obstetric team regarding the risks and benefits, 3 g of magnesium was given slowly in a bag of fluid. After discussion with the on-call medical team, Amiodarone 300 mg was commenced peripherally. Blood tests including FBC, U+Es and TFTs were taken. Arterial blood gas was fundamentally normal. The on-call cardiologist was contacted and, because the patient was still tachycardic, he advised DC cardioversion.{Figure 2}

Due to the fact the patient had only just had her baby delivered, we needed to treat her as an aspiration risk. Modified RSI was performed with Alfentanil, propofol and rocuronium. During the act of intubation, the patient cardioverted to sinus rhythm. After a short duration to ensure sinus rhythm would be maintained, the patient was woken up and extubated following reversal with suggamadex. She was transferred back to the labour suite for close monitoring overnight and was discharged the next day. Echocardiogram showed no functional valvular abnormality. Blood profile from the incident revealed no electrolyte disturbance and thyroid function tests were normal. Haemoglobin dropped from 112 g/L pre-procedure to 101 g/L post-procedure.

 Discussion



Whilst development of SVT in pregnancy is not uncommon,[3] there is a dearth of literature of de-novo atrial fibrillation occurring during caesarean section in an otherwise healthy person with no cardiac background. The cause for development of AF remains unclear, though given the timing of onset of AF, the bolus dose of oxytocin must be considered. Whilst the BNF outlines 'arrythmia' as a side-effect of use of oxytocin, it does not specify regarding AF. When oxytocin is given as a rapid iv bolus dose, it has more effect on the cardiovascular system than when given as a slow infusion.[4] A recent consensus statement advocates giving a smaller initial bolus dose, as low as 1 IU of oxytocin, in cases that are low risk for uterine atony.[5]

We were fortunate in that the baby had been delivered prior to development of AF. It allowed us to use any pharmacological strategy we wished. Much work has been done to assess the safety of various anti-arrhythmic agents in pregnancy. Adenosine, due to its short half-life, is safe to give,[6] as are beta-blockers.[7] Amiodarone should be avoided in the first trimester due to risk of teratogenicity, but can be used in emergency situations thereafter.[8] Other pharmacological options for SVT that are safe to use in pregnancy are digoxin and calcium channel blockers Verapamil and Flecainide. DC Cardioversion is felt to be safe at all stages of pregnancy with the risk to foetus being minimal.[9] Previous studies have highlighted the fact that women who developed AF peri-operatively were all found to be hypomagnesaemic.[1] The use of magnesium in SVT must be balanced with its tendency to cause uterine atony.

Whilst there is plenty of literature related to development of SVT in pregnancy,[2],[7],[10] this case report highlights the diagnosis and management of fast atrial fibrillation during an elective caesarean section.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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