Cardiac Case Study: August 2008

Management of Cardiac Disease in Pregnancy 

Management of Cardiac Disease in Pregnancy

By David Scott Vadnais, MD, Cardiology Fellow, Emory University School of Medicine

A 24-year-old Hispanic female 23-weeks pregnant presented to the emergency department of a local hospital with syncope and left-sided, pressure-like chest pain radiating to the back. These symptoms were accompanied by shortness of breath and palpitations roughly 30 minutes in duration. On arrival, the patient experienced a near syncopal event with visual loss compared to a "black curtain." Her hearing and sensation were intact, but some slurred speech was present.

Local hospital records revealed elevated troponin levels from 1.8 to 3.54 ng/ml and an electrocardiogram (EKG) with inverted T waves in leads V1 through V3. Her echocardiogram was normal, and computed tomographic angiography of the chest was normal. Her only reported past medical history was preeclampsia, including a previous miscarriage. She reported taking prenatal vitamins and denied any history of alcohol or drug abuse.

Patient’s EKG showing delta wave.

On presentation at Emory University Hospital, the patient's vital signs were normal. Her neurological exam was unremarkable and her cardiovascular exam only demonstrated a flow murmur. Her complete blood count and metabolic panel were within normal limits.

The patient's medical assessment seemed characteristic of Wolff-Parkinson-White syndrome (WPW), a condition in which an accessory pathway conducts atrial depolarization alongside the normal atrioventricular node, resulting in premature ventricular stimulation. The condition is distinguished by a short PR interval and a delta wave present on a surface EKG.1,2 It was on this basis that we made a preliminary diagnosis of WPW in our patient (Figure 1). WPWhas a prevalence of 0.15% to 0.25% in healthy subjects and is associated with a sudden death rate of 0.1%.3

The first challenge in treating a pregnant cardiac patient is confirming and refining diagnosis to determine an appropriate treatment protocol. Imaging tests used in cardiac diagnostics generally involve some level of radiation exposure, and even relatively small amounts can be harmful to a developing fetus. In general, the treating physician must weigh the potential benefit of the test for the mother against the potential exposure risk for the fetus. The maximum safe dose of radiation for pregnant women is 0.5 rad, above which the risk of defects increases (Table 1).4 Radiation exposure of many common imaging procedures exceeds this recommended limit (Table 2).4-6 In light of these data, our team consulted with an obstetrician and confirmed electrophysiology studies (EPS) would be acceptable with close fetal monitoring. EPS confirmed the accessory pathway.

Fetal Risk From Radiation Exposure and Fetal Radiation Exposure

Because most medications cross the placenta and are potentially harmful to the fetus (Table 3), drug therapy poses another challenge in treating pregnant cardiac patients.7 In light of this risk, we recommended ablation to correct the ventricular pre-excitation. Ultimately, the patient underwent 5.1 minutes of fluoroscopy-guided ablation, with lead shielding employed to minimize harm to the fetus, resulting in a total estimated fetal exposure of 170Mrad — 30Mrad from the CT and 140Mrad from EPS — well under the 0.5 rad maximum recommended exposure.

Antiarrhythmic Drugs and Pregnancy

The patient subsequently was discharged home with no medical therapy and, to date, has experienced no recurrence of arrhythmias or symptoms.

Referencesheart

  1. Cay S, Topaloglu S, Aras D. Percutenous catheter ablation of the accessory pathway in a patient with Wolff- Parkinson-White syndrome associated with familial atrial fibrillation. Indian Pacing Electrophysiol J. 2008;8(2):141-145.
  2. Keating L, Morris FP, Brady WJ. Electrocardiographic features of Wolff-Parkinson-White syndrome. Emerg Med J. 2003;20(5):491-4933.
  3. Munger TM, Packer DL, Hammill SC, et al. A population study of the natural history of Wolff-Parkinson-White syndrome in Olmsted County, Minnesota, 1953-1989. Circulation. 1993;87(3):866-873.
  4. Presbitero P, Prever SB, Brusca A. Interventional cardiology in pregnancy. Eur Heart J. 1996;17(2):182-188.
  5. Task Force on Pulmonary Embolism, European Society of Cardiology. Guidelines on diagnosis and management of acute pulmonary embolism. Eur Heart J. 2000;21(16): 1301-1336.
  6. Koren G, ed. Maternal-Fetal Toxicology. 2nd ed. Marcel Dekker: New York, NY; 1994:515.
  7. Tateno S, Niwa K, Nakazawa M, Akagi T, Shinohara T, Yasuda T. Arrhythmia and conduction disturbances in patients with congenital heart disease during pregnancy:
    multicenter study. Circ J. 2003;67(12):992-997.
  8. Tan HL, Lie KI. Treatment of tachyarrhythmias during pregnancy and lactation. Eur Heart J. 2001;22(6):458-464.

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