Carlos Andrés Luna^*, Juan Manuel Gómez^**

CASE 1

This case dealt with a 20-year-old patient in her 31^st week of pregnancy, suffering her first episode of precordial pain, palpitations and syncope. There was no other pertinent personal background. Electrocardiogram revealed paroxysmal supraventricular tachycardia (PSVT).

She received 100 mg metoprolol every 8 hours, 200 mg amiodarone every 12 hours and 5,000 U dalteparin daily during hospitalisation. Laboratory tests were normal and foetal monitoring was satisfactory. Echocardiogram showed normal ventricular and valvular function. Internal medicine and gynaecology decided to perform an abortion on the expectant mother to optimise her antiarrhythmic management, following pulmonary maturation. The anaesthesiology team on shift found the patient in the operating room, haemodynamically stable, asymptomatic, without uterine activity, suffering from PSVT and having cardiac frequency (CF) of around 200. She did not respond to frequency control with vagal manoeuvres; adenosine was not available.

The following questions arose: What form should management take? Should caesarean be carried out under conductive general anaesthesia? What were the haemodynamic implications? Was this a case of cardioversion in an asymptomatic patient? Could conduct be postponed and another treatment proposed?

The anaesthesiologist´s decision was to suggest remitting the patient to fourth level attention for electrophysiological evaluation. On being admitted to the reference institution she presented auricular fibrillation with adenosine dose and return to PSVT. The case was defined as arrhythmia involving a high risk of sudden death and she was hospitalised in an intensive care unit (ICU). Metoprolol and amiodarone were suspended and verapamil and propafenone were initiated, without obtaining CF control. Five days later electrocardiographic control revealed Wolff Parkinson-White syndrome (WPWS). Arrhythmia with high risk of sudden death was considered. Antiarrhythmic was established with 40 mg sotalol every 12 hours and sinus rhythm was regained. The patient voluntarily left the gynaecological service three weeks later and returned two weeks later for attention during vaginal birth, without epidural analgesia and with no maternal or neonatal complications. The electrophysiology service carried out ablation of the left posterolateral accessory pathway one month later.

CASE 2

A 26-year-old patient, G2P1, had a background of supraventricular tachycardia (SVT) prior to becoming pregnant which had been treated with propafenone. She was remitted to fourth level of attention during her 10th week of pregnancy due to having a clinical picture of palpitations, asthenia and adynamia (92/51 TA, 185 CF), which did not improve with metoprolol EV. Electrophysiology suspended propafenone in the ICU and began treatment with 160 mg sotalol every 12 hours, sinus rhythm being regained. She left having regained control of CF.

She consulted again at 30 weeks for palpitations and general discomfort (180 CF). Electrophysiology, on this occasion, decided to continue with 80 mg sotalol dose every 12 hours; rhythm was stabilised and she left for outpatient control. She presented a new episode of palpitations and paresthesia of the left hemibody during the farmaco34^th week of pregnancy, without uterine activity (104/67 TA, 120 CF). Foetal monitoring revealed a foetal cardiac frequency (FCF) of 120, leading to the electrophysiologist treating the case to hospitalise her for FCF monitoring.

Later monitoring revealed foetal reactivity (150 FCF); foetal echocardiogram was normal. It was decided to discharge her and begin outpatient control with the same management. The patient had satisfactory evolution during the rest of her pregnancy, accompanied by excellent control of her tachycardia with sotalol. She consulted again during the 38th week of her pregnancy for a reduction in foetal movements; this meant that she was programmed for emergency surgery which was managed with epidural anaesthesia with catheter without cardiovascular events being presented during the intraoperative or postoperative period, having satisfactory evolution during the immediate puerperium.

The incidence of arrhythmia has increased frequency as pregnancy progresses, being partly explained by metabolic, hemodynamic and hormonal changes(1-3). Four principles must be applied in managing arrhythmia. It must be correctly identified. Secondly, treatment must be based on the severity of the symptoms, risks and benefits of medical therapy. The fewest medicaments at the lowest effective dose must be used. Fourthly, the medicament having the best history of safety during pregnancy must be used(1,2,3,4,13).

An echocardiogram must be considered in the search for structural anomalies, electrolytic disorders and hyperthyroidism(5). The most commonly described arrhythmias are ventricular extrasystols and supraventricular ones, generally having a benign course(5,6,13). SVT as first episode has a 34% risk of being presented in pregnant women and 29% for exacerbations. Two mechanisms are generally considered regarding its origin: nodal re-entry tachycardia and re-entry tachycardia caused by the participation of anomalous pathways. The latter mechanism occurs in accessory pathway-carrying patients, whether occult or manifest such as WPWS(6,7).

Precautions must be taken with antiarrhythmic therapy during the period of organogenesis which might affect the foetus. Changes in pharmacokinetics related to pregnancy alter therapeutic concentrations, increase intravascular volume, reduce plasmatic protein concentration, increase renal clearance, increase secondary hepatic metabolism at progesterone level and intestinal absorption becomes altered by changes in gastric secretion and intestinal motility(8).

Perioperative management of a patient suffering from cardiac disease must include remitting her to a specialised centre for multidisciplinary management, considering interventions reducing risk, anticipating the moment of birth in all cases, considering an early epidural technique for reducing cardiac load(9) Medicaments used during caesarean section such as oxytocic and vasoactive drugs may precipitate PSVT; reduced auricular filling during conductive anaesthesia is related to arrythmogenicity(10). The left ventricle´s telediastolic volume becomes reduced at abnormally high frequency thereby compromising cardiac output and thus uterine blood flow(11). Epidural analgesia during labour contributes towards reducing maternal catecholamine levels, reducing the risk of hypotension and thereby avoiding deterioration of placental flow(12).

Most antiarrhythmic drugs used in the acute treatment of pregnant women and their maintenance are classified in category C (animal studies have suggested risk, but no confirmatory studies have been carried out on humans). Beta-blockers are generally considered to be safe during pregnancy, except for atenolol which has been implicated in retarding intrauterine growth. Beta-1 selective blockers (metoprolol) should avoid B2-mediated peripheral vasodilatation and uterine relaxation effect. Calcium-antagonist drugs seem to be safe during pregnancy.

They are used for controlling frequency in SVT; however, foetal bradycardia, ventricular auricular block, hypotension and even death have been documented. Adenosine has been considered as being the drug of choice when vagal manoeuvres have failed as it does not have negative effects on the mother or the foetus. Digoxin is considered the safest drug during pregnancy and breast-feeding; it has been used for controlling foetal SVT. Amiodarone has high iodine content, easily crosses the placenta, produces foetal goitre, hyper- or hypothyroidism, retarded intrauterine growth and prematurity. It should only be used if other therapies have failed and a life-threatening situation is presented(13,14,15,16). Sotalol prolongs the potential for action and acts as a non-selective beta-blocker (class 3 and class 2); it is safe and effective in controlling SVT, crosses the placenta and has not been shown to be teratogenic. Bradycardia and block in the new-born have been reported, but its monitoring must be extended for 24 to 48 hours following birth. The American Academy of Paediatrics considers sotalol to be safe during breast-feeding(17,18).

The Wolff Parkinson-White syndrome usually manifests itself in young adults and in some women during pregnancy. It involves the presence of an auricular-ventricular accessory conducting pathway. Pre-excitation means that early deflection is produced in an ECG, called delta wave. Calcium-antagonists and digoxin are contraindicated in its management because they can block auricular-ventricular conduction and dominate nervous impulse by aberrant pathway. Cardioversion is indicated in emergencies, having no impact on haemodynamics or foetal wellbeing. Radiofrequency ablation of the aberrant pathway is the treatment of choice when dealing with antiarrhythmic therapeutic failure; an electrode destroys areas of the myocardium or tissue conducting and maintaining arrhythmia. Organogenesis precludes using a fluoroscope during the first trimester of pregnancy; radiological protection techniques allow it to be carried out during more advanced trimesters. Even though cases have been reported in the literature, risk is potentially low and acceptable in cases of maternal SVT (19,20,21,22,23,24,25).

An anaesthesiologist is not just trained to give anaesthesia but must also be able to propose, suggest and interact with the medical-surgical team in ensuring a patient´s wellbeing.

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2. Kron Jordana. Arrhythmias in the pregnant patient: Current concepts in evaluation and. management. Interv Card Electrophysiol (2007) 19:95-107.

3. Adamson Dawn L. Managing palpitations and arrhythmias during pregnancy. Heart 2007; 93:1630-1636.

4. Page, Richard L. Treatment of arrhythmias during pregnancy. AM HEART J 1995;130:871-6

5. Delacretaz Etienne. Supraventricular Tachycardia. N Engl J Med 2006; 354:1039-51.

6. Gómez Jorge R, Márquez Manlio F. Arritmias en el embarazo ¿Cómo y cuándo tratar? Archivos de cardiología de México, Vol. 77 Supl. 2/Abril-Junio 2007:S2, 24-31.

7. Narula Onkar S. Wolff-Parkinson-White Syndrome: A Review. Circulation 1973;47;872-887

8. Alberca Vela Teresa, et al. Arritmias y embarazo. Rev Esp Cardiol 1997; 50: 749-759.

9. Camargo Assis Francisco M. Sarquis Saad Tonny Alberto. Manejo perioperatorio de la paciente embarazada con enfermedad cardiaca. Rev. Col. Anes. 34:39, 2006.

10. K. Robins. Supraventricular tachycardia in pregnancy. British Journal of Anaesthesia 92 (1): 140 - 3 (2004)

11. Miller Ronald, Miller Anestesia 6ta Edición. Elsevier 2005 pag 2319 - 2325

12. Duke James, Anesthesia Secrets. Elsevier Health Sciences, 2005 pag 439

13. Joglar Jose. Antiarrhythmic drugs in pregnancy, Current Opinion in Cardiology 2001, 16:40-45

14. Ferrero Simone. Maternal arrhythmias during pregnancy. Arch Gynecol Obstet (2004) 269:244-253

15. ACC/AHA/ESC Guidelines for the Management of Patients with Supraventricular Arrhythmias. Circulation. 2003;108:1871-1909

16. H. L. Tan and K. I. Lie. Treatment of tachyarrhythmias during pregnancy and lactation. European Heart Journal (2001) 22, 458-464

17. Taking Sotalol during pregnancy and breastfeeding. Disponible en http://drugsafetysite.com/sotalol/

18. Sung, Ruey J. Intravenous sotalol for the termination of supraventricular tachycardia and atrial fibrillation and flutter: A multicenter, randomized, double-blind, placebo-controlled study. American Heart Journal. Volume 129(4), April 1995, pp 739-748

19. Ahmad A. Ahmad Wolff-Parkinson syndrome in pregnancy: risks and management dilemmas-a review of literature. Eur Clinics Obstet Gynaecol (2008) 3:123-126

20. Dierdorf Stoelting, Anestesia y enfermedad coexistente. 4ta. Edición. Elsevier, 2003 pag 86 - 89

21. Y. Wang, C. Chen, H. Su, M. Yu . The impact of maternal cardioversion on fetal haemodynamics European Journal of Obstetrics & Gynecology and Reproductive Biology, Volume 126, Issue 2, Pages 268-269

22. Wellens Hein ¡J.J. Catheter Ablation for Cardiac Arrhythmias. N Engl J Med 351; 12, Sept 2006.