34 weeks pregnant (KG- Done)

5990113

G8P6 41 y.o. female with history of afib w/RVR in the setting of pregnancy in 2009 and stillbirth in 04/2024 who presents to the stabilization room from OSH for afib w/RVR in the setting of approx. 34w gestation based on bedside US. Per report, pt began feeling sob with fast heart rate and dizziness last night, but as it continued today, she presented to the outside ED. Her EKG showed possible afib w/RVR w/rates into 180s, down to 140s after metoprolol. Her dimer was also nearly 2000, so she was transferred here for mgmt of atrial tachycardia in the setting of high risk pregnancy. On arrival, pt endorses reported hx and reports no new complaints at this time. She states she can still feel baby moving, has not felt contractions, and has not had any leakage of fluid. She believes her LMP was approx. Aug, but her periods are very irregular.  Did not seek prenatal care due to anxiety surrounding previous preg ending in stillbirth.

41 y.o. female presenting with atrial tachycardia in the setting of high risk late term pregnancy. As the patient arrived to the stabilization room, report was taken from EMS. Patient transferred to STAB cart. Primary survey completed while patient placed on oximetry, cardiac monitoring, and cuff blood pressure monitoring. Intravenous access established and initial blood tests sent. Secondary survey completed.

 

This patient presented for evaluation of cardiac and/or pulmonary concern. Differential includes any life/limb threatening pathology, including but not limited to pulmonary embolism, pulmonary edema/heart failure, pleural effusion, pneumothorax, COPD/asthma exacerbation, ACS, arrhythmia, aortic dissection, AAA, structural cardiac pathology, among others.  

 

 OB and L&D at the bedside

 Bedside U/S w/tachycardia, grossly preserved EF, possible dilated RV in parasternal views, but not reproduced on apical view, no effusion, no blines; fetal exam was notable for movement, gross BPD approx. 38w (not ideal positioning over skull), and FHR 160s

 EKG w/atrial tachycardia, no visible p waves, nearly regular rhythm; c/f possible afib w/RVR vs SVT vs atrial flutter

 With nearly regular rate, SVT was a possibility, so attempted adenosine 12mg with return to previous rhythm

 Pt's pressures became softer, lowering to SBP in the 80s; a-line placed by Dr. Lauren Pitzer

 Also added Mag level and gave 1L LR and 2g Mag empirically

 Administered 5mg IV metoprolol with temporary improvement in rates to 140s

 CT w/no PE, possible undx'd pulm htn

 On return to stab, attempted repeat dose of 12mg adenosine, again with return to previous rhythm

 Considered other rhythm control agents, but amiodarone and digoxin have high toxicity for fetuses, and as pt's pressures are soft, diltiazem would likely further lower pressures

 Since pt had a transient response to metoprolol, attempted esmolol infusion, but patient's pressures dropped precipitously with MAPs down to th 40s; immediately turned off drip; pt maintained pulses and was rouseable. She had slow improvement to MAPs in the 50s but did not rise much further than that.

 As pt was now unstable, performed synchronized cardioversion at 200J using etomidate for sedation with conversion to NSR

 Pt developed significant anxiety and carpopedal spasm, given 1mg ativan with relief

 Labs notable for neg lactate, normal gas, neg trop, normal chem, anemia, which could be 2/2 anemia of pregnancy

 Per cards: suspect afib w/RVR, rec 12.5mg metoprolol tartrate q6h

 Will admit to MICU in the setting of high risk late term pregnancy w/previous afib w/RVR c/b stillbirth

 

 Summary: unstable afib w/RVR in the setting of high risk late term pregnancy, admitting to MICU w/OB following

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MY Comment, by KEN GRAUER, MD (5/19/2025):

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Two aspects of today’s case merit special attention: i) The rhythm diagnosis; and, ii) Treatment considerations of the rhythm diagnosis, given the pregnant state of this patient.

The Rhythm Diagnosis:

For clarity in Figure-1 — I've reproduced the patient's initial ECG. There was uncertainty about the rhythm when the patient was first seen.

• That the rhythm was supraventricular and tachycardic was obvious from the narrow QRS in all 12 leads — and the rapid rate.
• KEY Point: Although at first glance, the rhythm in Figure-1 may look regular — it is not regular. That the rhythm is actually irregularly irregular (with slight-but-real variation in the R-R interval throughout the entire long lead II rhythm strip) — can be verified within seconds by use of calipers (To Emphasize — With practice, the irregular irregularity of this rhythm can be immediately recognized without calipers, as I was able to do).
• There are no P waves in any of the 12 leads.
• Therefore: The finding of an irregularly irregular rhythm with narrow QRS and no P waves — defines this rhythm as AFib (Atrial Fibrillation), here with a rapid ventricular response.
• NOTE #1: It is common for AFib with a rapid ventricular response to "look" regular — which may lead to misdiagnosis of a reentry SVT rhythm (such as AVNRT or orthodromic AVRT). While most patients tolerate IV Adenosine — this medication is not without potential for side effects. Given that Adenosine is not effective for AFib — recognizing today's rhythm could have avoided the trial of Adenosine.
• NOTE #2: Review of the magnified insert of lead V1 (in the upper right corner of Figure-1) — suggests that there is atrial activity in this lead. But the vertical RED lines that I have highlighted are not flutter waves. It is common for there to be transient "organization" of AFib wavelets — and when this happens, you may see atrial deflections that almost look regular in lead V1 (which is the closest lead for recording atrial activity). But AFlutter (Atrial Flutter) is characterized by regular atrial activity, that in a patient not on antiarrhythmic medication — typically manifests an atrial rate range between ~250-350/minute. Therefore — the irregularity of the atrial activity in Figure-1, which at times far exceeds 300/minute rules out AFlutter as the rhythm diagnosis.

Figure-1: I've labeled the initial ECG in today's case.

Treatment Considerations of AFib in a Pregnant Patient:

My review of AFib Treatment during Pregnancy encompassed the following publications: Tamirisa et al ( J Am Coll Cardiol EP 1:120-135, 2022) — Cacciotti and Passaseo ( J Atr Fib 3(3):295, 2010) — and — Youssef ( Eur Soc Card 15(17), 2019):

• Overall — AFib is not a common complication of normal pregnancy. That said, I found it difficult to estimate the prevalence of this arrhythmia — as frequency estimates will depend on multiple factors including age and health status of the patient, and presence of precipitating factors.
• There are additional complicating factors in today's case. These include the patient's age (41 years old) and multiparous status (G8P6) — with lack of prenatal care (because of patient anxiety resulting from the previous pregnancy ending in stillbirth). Estimated gestation of this current pregnancy = 34 weeks. Of note — this patient had a previous episode of AFib in 2009 during one of her earlier pregnancies!

Regarding Treatment:

• First priority (as for any patient with new, rapid AFib) — is to ensure hemodynamic stability. If/as needed — electrical cardioversion appears to be safe at all stages of pregnancy. (During and after electrical cardioversion — fetal monitoring is advised, given the risk of fetal arrhythmias).
• Look for Potential Precipitating Factors — which is critical, since if an underlying cause of AFib is present — this will greatly affect treatment decisions (Rule out hyperthyroidism, alcohol use, cocaine or other illicit drug use, sympathomimetic or other stimulant medication, electrolyte disturbance — adult congenital heart disease — rheumatic heart disease — peripartum cardiomyopathy — or other form of underlying heart disease) ==> An Echo, TSH, CBC, electrolytes, etc. — all part of the immediate work-up.
• Medications for Rate Control — Beta-blockers are recommended as 1st-line for AFib rate control. Digoxin has a long history of being safe in pregnancy (assuming no preexcitation). Verapamil is a 2nd-line agent (and is favored over Diltiazem). And, if rate control with hemodynamic stability can be achieved — it may be reasonable to hold off decision of cardioversion, given a high percentage of patients who spontaneously convert to sinus rhythm within the first 24 hours of hospitalization.
• Amiodarone — should not be used in pregnancy (significant adverse effects).

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NOTE: I'll recommend the above reference by Tamirisa et al — as this is a 2022 State of the Art Review by JACC on Arrhythmias in Pregnancy. This article contains detailed reference tables of specific drugs and treatments for the various arrhythmias during pregnancy.

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