266 Br J 1992;67:266-8

CASE REPORTS Br Heart J: first published as 10.1136/hrt.67.3.266 on 1 March 1992. Downloaded from Incessant atrial accelerated by pregnancy

J Colin Doig, Janet M McComb, Douglas S Reid

Abstract sinus rhythm or affect the ventricular response A 24 year old patient presented with rate. Metoprolol and in combination incessant atrial tachycardia during the slowed the ventricular rate to 185 beats/min course of a twin pregnancy. Medical but the diurnal fluctuation in PP and RR treatment slowed the ventricular res- intervals continued. Flecainide was therefore ponse without restoring sinus rhythm. introduced in place of metoprolol and digoxin. During labour the tachycardia spontan- This slowed the atrial rate to 115 beats/min and eously reverted to sinus rhythm. Sub- allowed transient episodes of sinus rhythm at sequently the same was 75 beats/min to appear with a frontal P wave documented with a slower ventricular axis of + 10°. The PR interval was 200 ms with response than during pregnancy. no evidence of pre-excitation (fig 2). This was considered a satisfactory interim result and the patient was discharged on oral flecainide Case report 100 mg three times daily. During the next At 21 weeks' gestation of a twin pregnancy a 24 month the QRS duration increased from 80 ms year old patient was transferred for man- to 100 ms and the heart rate was never consis- agement of incessant supraventricular tently below 130 beats/min on Holter monitor- tachycardia because of concerns about the ing. Because of this inadequate rate control,

effect on placental function. There was a three flecainide was stopped and amiodarone was http://heart.bmj.com/ month history ofpalpitation and chest discom- introduced at a dose of 800 mg a day for one fort, dizziness, and exertional dyspnoea that week and maintained at 400 mg daily. This had begun eight weeks into the pregnancy. slowed the heart rate to 110 beats/min. On this There was no history ofviral illness and she had treatment, she felt better, but was considerably been otherwise healthy with no previous his- restricted in her exercise capacity by palpita- tory of palpitation. At admission the heart rate tion, fatigue, and dyspnoea. There was no was 200 beats/min and systolic blood pressure clinical evidence of or com- was 90 mm Hg. Her electrocardiogram showed promised fetal development. on September 30, 2021 by guest. Protected copyright. a narrow QRS complex tachycardia with At 31 weeks' gestation two healthy infants upright P waves in the inferior limb leads and were delivered vaginally by forceps. Sinus VI, with a frontal P wave axis of + 900 (fig IA). rhythm returned spontaneously and the moth- The PR interval was 140 ms. Occasionally non- er's heart rate fell below 100 beats/min during conducted P waves of identical configuration the first stage of labour. After delivery she and timing were seen during the tachycardia reported that palpitation had ceased and she (fig 1B). The rate of the arrhythmia showed remained in sinus rhythm when seen in out- considerable diurnal variability ranging from patients two weeks after hospital discharge. 135 to 210 beats/min. Isolated ventricular Amiodarone was stopped at this time and her extrasystoles did not reset the tachycardia. electrocardiogram was similar to that in fig 2. There was QRS alternans at ventricular rates The diagnosis was therefore assumed to be faster than 190 beats/min. Haematological pregnancy related atrial tachycardia and this studies, urea and electrolytes, and liver func- was supported by the prominent left atrial tion tests were normal. A free thyroxine plasma component to the P wave in sinus rhythm. She Regional concentration of 164 nmol/l (normal range was re-referred, however, six months after Cardiothoracic with non-cardiac at which Centre, Freeman 60-140) and thyroid stimulating hormone con- delivery symptoms Hospital, Newcastle centration of 1-4 IU/I (normal range 0 15-3-2) time an electrocardiogram showed return of rate of 1 15 upon Tyne were consistent with pregnancy. Transthoracic atrial tachycardia with a ventricular J C Doig treat- x were normal. beats/min. She was on no antiarrhythmic J M McComb echocardiography and chest ray D S Reid Fetal echocardiography showed normal ment. Correspondence to and rates. Dr J Colin Doig, University The arrhythmia did not respond to carotid Department of , Valsalva manoeuvres or Discussion Regional Cardiothoracic sinus massage, sinus Centre, Freeman Hospital, intravenous verapamil. Digoxin was used with- Pregnancy is frequently associated with Newcastle upon Tyne, and increased has NE7 7DN. out benefit and cardioversion did not restore tachycardia ectopic activity Incessant atrial tachycardia accelerated by pregnancy 267 tachycardia such as was present in this patient is uncommon and has rarely been reported during pregnancy.89 It has not previously been seen reverting to sinus rhythm during labour. An automatic atrial tachycardia more typically Br Heart J: first published as 10.1136/hrt.67.3.266 on 1 March 1992. Downloaded from occurs in childhoodl'01 or complicating heart disease'2 or metabolic upset including digitalis toxicity.'3 In this case, recurrence of the same tachycardia some months later suggests that the patient had a potential for atrial tachycardia unrelated to pregnancy, but which first presen- ted at an accelerated rate during pregnancy. The mechanism of the tachycardia in this patient was probably enhanced sympathetic reactivity of an ectopic atrial focus. This !:: ..4 accords with the increased plasma cate- cholamine concentrations and the increased adrenergic receptor sensitivity during preg- nancy.4 " Increased atrial stretch due to plasma volume enlargement might also be implicated. The possible influence of the high concentra- '~~~.!..~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..Fc tions of oestrogen and progesterone in preg- nancy is unknown. An enhanced response to S a. 5... I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.... prostaglandins has been reported in preg- nancy,'5 and in susceptible patients this could perhaps induce an atrial tachycardia. Thyrotoxicosis could also facilitate' atrial ; but there was no clinical or biochemical evidence of thyroid overactivity. -e:;-:~~~~~~~ ~ ~~..~~~~~~~~~~~~~~~~~~_. Why the arrhythmia stopped during labour is ~ IK not clear. ~~~~~~~~~~~~~O' Because the persistent atrial tachycardia might have caused congestive cardiac failure in our patient'6'8 or have affected placental func- tion and subsequent fetal development'9 we tried to reduce the ventricular rate response when sinus rhythm could not be restored. The in pregnancy http://heart.bmj.com/ Figure I (A) Electrocardiogram showing narrow QRS tachycardia. (B) Rhythm management of such arrhythmias strip showing non-conducted P waves of identical configuration and timing during is difficult. Verapamil, digoxin, or cardio- tachycardia.I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ selective f blockade are appropriate and usually well tolerated.202' Flecainide seems to in the and the ventricle be safe and cardioversion is not contrain- been noted both as an throughout pregnancy.'2 Paroxysmal dicated.' Amiodarone is regarded agent supraventricular tachycardia has been seen' of last resort because of concerns about neon-

in breast milk.2324 on September 30, 2021 by guest. Protected copyright. occurs in a patient with a history of atal goitre and its presence and usually to insert a tem- arrhythmias before preg- An alternative treatment is supraventricular to terminate the arr- nancy or in a patient with pre-existing porary pacing electrode rheumatic heart disease.5 Such arrhythmias hythmia or convert it to atrial . but the Though appropriate radiation protection could usually occur in the third trimester6 to be is unknown.7 Persistent atrial be used, pacing was not thought likely true incidence successful in our patient and we thought that might further compromise placental function. This rare case highlights the risk that inpatients with the potential for atrial tachycar- dia the condition can be precipitated and accelerated by pregnancy. The arrhythmia was persistent and led to unrealised concerns about placental function but it reverted to sinus rhythm early during labour. Treatment of a persistent tachycardia in pregnancy may be potentially toxic to the mother or fetus or both. Despite a twin pregnancy and incessant supraventricular tachycardia our patient delivered two healthy infants.

1 Mendelson CL. Disorders of the heartbeat during preg- nancy. Am J Obstet Gynec 1956;72:1268-301. 2 Sullivan JM, Ramanathan KB. Management of medical problems in pregnancy-severe cardiac disease. N Engl J Figure 2 Electrocardiogram after return to sinus rhythm. Med 1985;313:304-9. 268 Doig, McComb, Reid

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