ABSTRACT

CORRESPONDING AUTHOR:
Dr. Sunanda N,
No. 1312, 5th Cross,
Paduvana Road,
Kuvempunagar,
Mysore-570023.
Email: sunanda_n@rediffmail.com

ABSTRACT: Cardiac disorders in pregnancy poses special challenges to health care providers. Complications may arise at any stage due to increased hemodynamic load imposed by pregnancy or because of impaired cardiac performance often seen in these patients. There is an increased risk of thromboembolism, anticoagulant related hemorrhage, fetal wastage, congestive cardiac failure in pregnant women with mechanical heart valve. Pregnancy in such patients is a high risk venture. In order to have good outcome, the care of such patients must involve multi-disciplinary approach and should be done in a well-equipped centre with adequate support system.

KEYWORDS: Mitral valve replacement, pregnancy.

CASE REPORT: A 22 yrs. old primigravida with 37 wks gestation was referred from a primary health center for Rheumatic heart disease-post mitral valve replacement for safe confinement. She conceived spontaneously and pregnancy was confirmed at nearby Primary Health Center. She had frequent visits to cardiologist also.

Patient had leg & hip joint pain and headache for which she was evaluated and diagnosed to be case of Rheumatic heart disease- severe Mitral regurgitation, infective endocarditis complicated by right common iliac artery aneurysm. Patient underwent surgery for both at different setting. Right common iliac artery aneurysm excision done in December, 2008 and mitral valve replacement done a month later using St Jude valve 27- mechanical valve. Since then she is on tablet Warfarin 3mg/4mg, once a day alternate day and penidure prophylaxis. When pregnancy was confirmed her medication was changed to inj. Heparin 5000 IU with weekly aPTT/ PT monitoring and titrating the dose accordingly. INR was maintained at >2.Before admission she was taking inj. Heparin 3500IU thrice daily.

On examination, patient was comfortable and belonged to NYHA (New York heart association) grade 1. She had a vertical scar in the mediastinum extending from the xiphisterum to 7cm below the suprasternal notch. Pulmonary area had a palpable P2, and systolic thrill. Prosthetic valve click was heard in the mitral area with an ejection systolic murmur in pulmonary area indicating pulmonary hypertension. Obstetric examination revealed a term relaxed uterus.

On admission patient was ordered a 2D echo which revealed normal functioning mitral valve prosthesis with no valvular or paravalvular leak, normal Left Ventricular function with ejection fraction of 65%.No obvious clots/ vegetation was detected however, mild mitral regurgitation was present. USG showed single live intrauterine gestation of 19 weeks with no obvious anomalies. Fetal echocardiography was done considering the risks, which was found to be normal. Coagulation profile was within normal limits

Further management was planned after consulting the cardiologist who advised to increase the dose of inj heparin to 4000 IU BD and to Continue heparin up to onset of labor. Heparin was to be stopped 6hrs prior to elective LSCS/induction. Post-delivery after ensuring hemostasis, warfarin was to be restarted at 2mg OD overlapping with heparin. Activated PTT and INR to be kept at 1.5-2 times the control value. After INR Value is achieved heparin was advised to be stopped.

A reserve of blood components (FFP’s, platelets, PRBC) was kept and infective endocarditis prophylaxis given. On 08/04/2014 patient set into labor spontaneously. Patient had a vacuum assisted vaginal delivery of an alive male baby of weight 2.75kg at 5:50pm.

Intrapartum and postnatal period was uneventful. Activated PTT was monitored during labor and in post natal period. Inj heparin was restarted 6hours after delivery and overlapped with tab. Warfarin 3mg OD at the time of discharge.

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DISCUSSION: Surgical valve replacement has allowed many patients with severe valvular heart disease to survive and lead near normal life. There are 2 broad categories of replacement valves each with advantage and disadvantages: Mechanical valve and Bioprosthetic valve. Further they are divided into:

Heterograft- bovine or porcine valve.

Homograft- human aortic valve.

Autograft- patients own pulmonary valve.

Mechanical valve are non-biological material.^{5, 6,7} They have advantage of durability but risk of thrombosis requires long term anticoagulant.

Bioprosthetic valves do not require anticoagulant but valve failure often occurs within 10-15years.^{8, 9, 10} Pregnancy has been reported to increase the rate of spontaneous valve deterioration.

St JUDE MECHANICAL VALVE

EDWARD BOVINE PORCINE BIOPROSTHETIC VALVE

All mechanical prosthetic valves are thrombogenic and require life-long anticoagulation to prevent thromboembolic complications.

In addition, pregnancy is a hypercoagulable state.¹¹choosing which type of anticoagulation to use during pregnancy is problematic, as there is no perfect choice from the available data.

Therefore, the major concerns associated with pregnant women with mechanical heart valves are thromboembolic complications, maternal bleeding, and increased fetal events.^12,13,14The use of Warfarin in pregnant women during the first trimester resulted in a high rate of abortion (34.9%). A similar incidence of abortion was found by Salazar and associates (37.5%) and Shannon et al., who reported a 37% rate of abortion.¹⁵

In contrast, in the Akhtar et al. study, spontaneous abortion occurred more frequently in the Heparin group, whereas Geelani and colleagues reported a similar incidence of abortion in Warfarin and Heparin groups. Many articles have shown that the use of Warfarin between 6 and 12 weeks’ gestational age results in a 6% to 10% risk of embryopathy.

The risk is probably lower if ≤ 5 mg of Warfarin is prescribed. A large number of studies have reported that the risk of thromboembolic events during pregnancy in patients treated with Heparin is approximately 10%, compared with a 3.9% risk with the use of Warfarin throughout pregnancy. The use of unfractionated Heparin during pregnancy can be problematic, with an attenuated response of activated partial thromboplastin time, variable sensitivities of aPPT reagents, and wide peaks or troughs with the use of subcutaneous unfractionated heparin.

Most studies have found that the risk of thromboembolic complications is greater with prosthetic valves in the mitral valve position than with those in the aortic position. As regards the maternal outcome, it is deserving of note that the Warfarin regimen is safer than Heparin.

UFH: unfractionated heparin

LMWH: low molecular weight heparin

CONCLUSION: Women who have prosthetic heart valves and are of a childbearing age should be counselled (ideally before conception) about the potential issues that might arise during pregnancy. Having a prosthetic heart valve puts both the mother and fetus at risk; therefore, the management of these women is required throughout pregnancy in a specialized program for high-risk patients by a multi-disciplinary team.

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