A case report of high-degree AV block in pregnancy

Abstract

Complete heart block is seldom seen in pregnant women and poses a challenge for further management. The available literature on this is scarce, and the management usually varies as per the discretion of the obstetrician and severity of the presenting symptoms. Here, we report a case of a G2P0 primi with a high-degree AV block that was managed with a temporary cardiac pacemaker, which resulted in the successful delivery of twins. Clinically, we suspected a mitochondrial genetic defect to be the underlying cause of the conduction defect. Through this case, we would like to emphasize on the involvement of a multidisciplinary approach for the management of every pregnancy complicated by a medical disorder and the provision of timely interventions to reduce maternal and perinatal mortality.

Introduction

Complete heart block (CHB) is an impairment in the conduction of electrical impulses from the atria to the ventricles through the three fascicles, namely, the right bundle branch, the left anterior fascicle, and the left posterior fascicle.^[1] A cardiovascular defect, including a conduction defect, is likely to be presented during pregnancy due to the altered hemodynamics seen in circulation as a result of the compensatory changes that occur in pregnancy.^[2] Most cardiac conduction defects are diagnosed in childhood, and the presentation of a congenital conduction disorder during the third trimester in pregnancy is rare.^[3] Here, we report the case of a 30-year-old primigravida with a trifascicular block diagnosed during the third trimester of pregnancy. CHB in pregnancy is rare; however, a diagnosis made during the third trimester is even rarer and the management of this requires an expeditated and a multidisciplinary approach to prevent complications during delivery and provide a favorable postnatal outcome for both the mother and the newborn.

Case Report

A 30-year-old primigravida at 35 weeks + 3 days gestation presented to the OBGYN Emergency Room at our institution with the complaint of breathlessness of 1 day duration. She was a case of type 1 diabetes mellitus who had in vitro fertilization - intra cytoplasmic sperm injection (IVF-ICSI) conception with Di chorionic di amniotic (DCDA) twins. On examination, her pulse rate was 63 beats per minute and her blood pressure was 130/70 mmHg. She had grade 3 pedal edema bilaterally. Examination of cardiovascular system was unremarkable with normal heart sounds without any murmurs. Serum electrolytes were checked and were found to be within normal limits.

Renal profile and serum electrolytes on admission were as mentioned in [Table 1].

Table 1: Serum electrolytes and Renal Functional Profile of patient

Her pregnancy was confirmed by serum Beta human chorionic gonadotropin (b-HCG) and dating scan. The patient was diagnosed with moderate anemia in the first trimester and treated with oral iron supplements and one dose of injection ferric carboxy maltose. The second trimester was uneventful, and she was on regular follow-up with endocrinologist for management of type 1 diabetes mellitus. In the third trimester, growth scan done showed adequate growth for both fetuses. There was an episode of elevated blood pressure at 29 weeks of gestation. The patient was put on corticosteroids for fetal pulmonary maturity and with magnesium sulfate for fetal neuroprotectio n in view of threatened preterm labor, after which she had an episode of diabetic ketoacidosis, which was medically managed.

The patient was admitted, and an electrocardiogram (ECG) was done, which revealed a second-degree Atrio-ventricular (AV) block. The patient was immediately taken up for an emergency Lower segment caesarean section (LSCS) with implantation of a temporary cardiac pacemaker as per the cardiology opinion obtained. Both babies had Apgar scores of 9/10 at birth. Intraoperatively, patient had atonic Postpartum hemorrhage (PPH), which was managed with Hayman sutures and oxytocin infusion. She was then shifted to the intensive care unit (ICU) and transfused with one unit of packed red cells in view of decreased hemoglobin. Cardiology opinion suggested a cardiac magnetic resonance imaging (MRI) and 24-h Holter monitoring. She was advised permanent cardiac pacemaker, but the patient was unwilling. An ophthalmology opinion was taken, and the patient was diagnosed with chronic progressive ophthalmoplegia with flecked retina. Considering her symptoms and clinical findings, Kearns–Sayre syndrome was suspected and a neurology opinion was sought for this. The diagnosis could not be confirmed as the patient was not willing for further workup. Patient’s vital signs improved, and she was discharged on postoperative day 6 against medical advice.

Discussion

The most common type of arrhythmia in pregnant women is paroxysmal supraventricular tachycardia. CHB is a disorder of the cardiac conduction system with a complete absence of conduction between the atria and ventricles.^[4] Medical literature on CHB in pregnancy is sparse. The management usually varies on a case-to-case basis. For women with heart block, labor and delivery could result in worsening of bradycardia due to uterine contractions displacing blood into the maternal circulation. Most women with heart block do well in labor and delivery, and having a pacemaker is not necessarily an indication for a cesarean section. Symptoms of heart block include breathlessness, palpitations, fatigue, and syncope. In such cases, a temporary pacemaker may be placed in the patient.^[5] A routine test such as a 12-lead ECG is often adequate to diagnose a CHB. To diagnose the underlying cause of the electrical abnormality in our patient, we proceeded with a cardiac MRI during the puerperal period. The cardiac MRI revealed a generalized hypokinesia with additional inferior wall hypokinesia and impaired left ventricular systolic dysfunction (Left ventricular ejection fraction (LVEF) of 46%) with preserved right ventricular systolic function (Right ventricular ejection fraction (RVEF) of 54%). Twenty-four-hour Holter monitoring was done and showed a sinus rhythm with intermittent 2:1 block, intermittent CHB, and intermittent trifascicular block, suggestive of a high-degree AV block. As the patient had a high-grade AV block and also was symptomatic, implantation of a permanent pacemaker was advised. In the case of our patient, the diagnosis of CHB was made in the third trimester. As she was symptomatic and had known comorbidities, a temporary cardiac pacemaker was indicated. CHB does not cause any specific pregnancy-related problems, except for few cases of Intra uterine growth restriction (IUGR) and preterm delivery.^[6] In the case of our patient, no complications were seen in both the babies and they had adequate growth. During the course of evaluation, the patient was also found to have progressive external ophthalmoplegia, and hence, we suspected Kearns–Sayre syndrome based on ocular and cardiac findings. This rare, mitochondrially inherited genetic defect usually presents with ocular and cardiac conduction defects, and most cases appear to occur as a result of a new spontaneous (de novo) deletion of a large amount (typically ~25%) of genetic material found in the DNA of mitochondria.^[7] However, as the patient was not willing for further workup, mitochondrial studies were not carried out to establish a diagnosis.

Conclusion

Multidisciplinary approach involving the primary care physician, obstetrician, anesthesiologist, cardiologist, intensivist, and neonatologist, along with the availability of a well-equipped ICU is vital for the management of high-risk pregnant women with cardiac conduction defects.^[1] Case-specific factors should be considered for cardiac pacing, along with abundant patient education and counseling. As the primary or family physicians may be the first line of contact for pregnant patients, a thorough investigation and routine ECG at each visit is encouraged to make the diagnosis at the earliest.

Consent

Written informed consent was obtained from the patient and her attender for the publication of this case report.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.