Anticoagulation During Pregnancy with a Mechanical Pulmonary Valve: Patient and Medical Perspective

Abstract

This article discusses the challenges of supporting a successful pregnancy in a woman with multiple prosthetic heart valves and a complicated cardiac history, from both the patient and provider perspective. The patient is a 29-year-old female with truncus arteriosus type I with initial neonatal VSD closure and right ventricular to pulmonary artery conduit. At the age of 13, she subsequently required truncal and pulmonary valve replacements with mechanical prostheses. Standardizing an approach to anticoagulation in pregnancy in women with prosthetic heart valves is not always possible. Her story demonstrates the importance of an innovative approach to unique cases; by extrapolating what is known about pregnancy and prosthetic heart valves, cardiologists can provide the best outcomes. Simultaneously, non-directive counseling is essential throughout this period to engage the patient in shared decision-making when balancing risks and benefits of each approach to anticoagulation.

Key Summary Points

Pregnancy is inherently a thromboembolic state, and valve thrombosis carries a 20% risk of mortality.

Pregnancy in women with mechanical heart valves requires a careful balance between the risk of thromboembolism in the mother and the risk of maternal and fetal hemorrhage and fetal malformation.

Data is limited on application of anticoagulation guidelines to pregnant women with mechanical heart valves; this is one of the few cases that discusses anticoagulation in a pregnant woman with a mechanical pulmonary valve.

Non-directive counseling must be utilized from pre-contraception to the postpartum period to balance the patient’s desire for pregnancy with realistic expectations for maternal and fetal outcomes.

Patient Perspective

If someone would have told me 10 years ago that I would now have a nine-month-old child that I was able to give physical birth to, I would have told them that they obviously didn’t know my medical condition or have spoken with my doctors. While I was in that time frame of adolescence and as I entered adulthood, I was always told I would never be able to carry a child to term on my own without great risk to myself and the child, because of my heart condition. My diagnosis at birth was truncus arteriosus, type I.

I have lived my entire life with this diagnosis and all that it entails, including multiple additional surgeries and two mechanical valves. I would be remiss if I did not express the gratitude that I feel that God has placed the right doctors in my life. This has enabled me to receive, what I believe to be, the best medical treatment and advice that a human being could ever be given.

I grew up in a family in which I was the oldest of three siblings. I never thought of myself as different than my two younger siblings, who have no cardiac issues. My family never allowed me to believe that I could not do something due to my medical condition. They always encouraged me to take calculated risks to accomplish my dreams. I must confess that, at times, I can be at a very obstinate person. Meaning, when I set my mind of to accomplish a task, that is what I will do.

I met the love of my life at 16 years of age and 10 years later we were married. I knew at this point I was going to take on what everyone called a dangerous decision. That was having a baby and creating my own family. Most everyone in my life told me that they were extremely worried about me doing this to myself, but they said they would support my decision. In my mind, I was determined, I was going to have a baby, no matter what anyone said or the obstacles placed in my way on this journey.

I wish I could say that conceiving a baby was extremely easy for me and that everything worked out on my first try, but it did not. The journey to having what I have referred to as “my miracle baby” took almost 3 years before I was blessed to have him come into my life.

This roller coaster of a ride entailed a multitude of trials that tested my body and mental well-being. A summarization of the physical aspect of what I endured were seven total pregnancies. These pregnancies resulted in five miscarriages and having to also have a dilation and curettage. As I would sometimes be alone and scared in the hospital, my faith in God was the only thing that guided me through these difficulties. I was told, on multiple occasions, by everyone in my inner circle to stop trying, that this was never going to work. I just knew that it would work. I truly believed that one of my main purposes in life was to be a mom. The support of my husband and family, who were there through it all, knew that if you told me I could not do it I would only push harder to accomplish my dream.

My first trimester of pregnancy was wonderful, I was delighted, but scared that it would end like the previous pregnancies. Doctors placed me on a medication called Lovenox^® (enoxaparin sodium), a blood thinner that would protect my valves, but it would not cross the placenta. I was advised that using this medication would be more of at the risk to me and my mechanical valves but no risk to the baby. I carefully weighed these risks and believed this to be the best choice since Coumadin® (warfarin, my previous medication) crosses the placenta and had a higher risk of birth defects toward the baby.

I began giving myself two shots a day. They had to be exactly 12 hours apart. I learned that Lovenox^® is only good for 12 hours at a time and then it is out of your system. I was used to dealing with Coumadin^®, which has an approximate 3-day lag. I knew if I missed a shot that my mechanical valves would not be protected.

Administering these shots were painful and the bruising became atrocious. I was on a 12-week cycle, during this time I had to give myself a shot in the same place which was already bruised, causing even more pain. One of the biggest side effects was it could cause vaginal spotting. This was extremely frustrating for me and caused great anxiety while being on this medication. I had spotting my entire first trimester and for approximately a week and a half into my second trimester. I was very emotional during this period, especially since I was already fragile with the experiences of my prior pregnancies.

After I made it through the first trimester. I was able to go back on my normal medication of Coumadin^®. This helped to relieve my anxiety about my mechanical valves and knowing they were once again fully protected.

As I am looking back at my entire pregnancy, it truly was the most incredible experience that I have ever gone through. I am beyond blessed that I was able to carry my child full-term and be able to give birth naturally (no cesarean, no epidural) and my son are completely healthy. There were no major complications throughout the entire process. I also believe that my obstetric team learned a lot from my pregnancy and delivery. I’m honored that my pregnancy was able to pave the way for women that come after me with two mechanical valves. I hope my experience gives others hope that even with this medical condition you can live a normal healthy life and have a family of your own.

Medical Perspective

Pregnancy in women with prosthetic heart valves poses unique challenges for the patient and provider. Pregnancy is inherently a thromboembolic state, and valve thrombosis carries a 20% risk of mortality [1]. Anticoagulation regimens are not standardized in this population. Each case requires a careful balance between the risk of thromboembolism in the mother and the risk of maternal and fetal hemorrhage and fetal malformation [2]. Pregnancy is especially challenging in women with right-sided mechanical valves, as these valves have a higher risk of thrombosis than left-sided valves [3].

In this case, a 29-year-old female with a history of truncus arteriosus type I was able to carry a pregnancy to term. She underwent repair as a neonate with ventricular septal defect (VSD) closure and right ventricular–pulmonary artery (RV-PA) conduit placement. She subsequently underwent truncal valve replacement with a 25 mm St. Jude mechanical valve and RV-PA conduit replacement with a 27 mm St. Jude mechanical valve. This procedure was complicated by complete heart block requiring placement of a permanent dual-chamber pacemaker. She was instructed to adhere to a strict international normalized ratio (INR) target of 4 after placement of the second mechanical valve.

She first presented to us after experiencing three miscarriages while on a warfarin-only anticoagulation regimen. After extensive risk–benefit counseling, the patient and the cardiology team jointly decided to lower the patient’s INR range to 2–3 to facilitate transition to enoxaparin for the first trimester. The patient experienced another miscarriage with the next pregnancy, even though she was able to transition to enoxaparin immediately upon learning she was pregnant. She was quickly transitioned back to warfarin after miscarriage.

The patient became pregnant for the fifth time and started enoxaparin at an estimated 3 weeks’ gestation. Her obstetrician recommended she start progesterone to further support this pregnancy. She was monitored with weekly anti-factor Xa levels, and changes to enoxaparin were made as needed. At 12 weeks’ gestation, she was transitioned back to warfarin. The patient’s cardiology team attempted to keep warfarin dosage below 5 mg to minimize risk of fetal malformation, but she did require a combined anticoagulation regimen (warfarin and enoxaparin) with up to 7 mg warfarin to maintain a therapeutic INR in the second semester. She maintained a warfarin-only regimen during the third trimester until just before delivery. INR dropped as low as 1.7 during the pregnancy. The patient continued low-dose aspirin throughout.

Pregnancy was further complicated by intermittent vaginal bleeding. In the first trimester, ultrasound showed subchorionic placental hemorrhage. The patient continued to experience vaginal bleeding in weeks 15–18, necessitating multiple clinic and emergency department visits to ensure she had not miscarried. She was eventually diagnosed with a small tear in her cervix. No changes were made to her anticoagulation regimen as a result of this bleeding, and bleeding stopped spontaneously.

The patient’s cardiac physical exam remained unchanged throughout pregnancy. However, monthly echocardiograms during the second and third trimesters showed that cardiac function changed at 30 weeks’ gestation. Echocardiogram at this time demonstrated increased aortic gradients suggestive of mild fluid overload. The patient was started on furosemide. Metoprolol was not started until after she underwent routine insulin resistance testing. Fetal echocardiogram performed during the second trimester did not show evidence of fetal cardiac abnormalities.

The patient was admitted to the hospital at 37 weeks’ gestation and started on a heparin infusion 2 days prior to scheduled induction. Heparin drip was held when the patient transitioned to the active stage of labor. The patient received remifentanil for pain control during delivery rather than neuraxial anesthesia, given her increased risk of bleeding. The patient delivered a healthy male infant at 37.2 weeks’ gestation weighing 3039 g and with Apgar scores of 6 and 8. Heparin was resumed when postpartum bleeding slowed, and the patient was then transitioned back to warfarin. She was discharged at 6 days postpartum on warfarin. At 16 days postpartum, furosemide and metoprolol were discontinued, and the INR target was increased to 2.5–3.5, with biweekly INR checks. Both mother and infant are doing well 6 months later.

As this case demonstrates, anticoagulation treatment in pregnant women with prosthetic heart valves is a delicate balance between maternal and fetal health. To date, anticoagulation regimens consisting of vitamin K receptor antagonists (VKA) have provided the best maternal outcomes, while low-molecular-weight heparin (LMWH) regimens have provided the best fetal outcomes [2, 4]. Women with prosthetic heart valves have significantly increased risk of complications in pregnancy and delivery compared to other women: miscarriage, late fetal loss, and postpartum hemorrhage have been shown to occur with greater frequency in women with mechanical heart valves compared with controls [8]. Our patient required a combined regimen of VKA and LMWH to promote pregnancy and prevent thromboembolism. Unsurprisingly, she experienced additional complications such as prolonged vaginal bleeding during pregnancy.

Data on anticoagulation in pregnant women with prosthetic heart valves are numerous, but applicability is limited. Prior research has largely focused on management strategies and outcomes in pregnancy of women with left-sided prosthetic heart valves [4–6]. Research on right-sided heart valves is rare, as these valves carry an increased risk of thrombosis even in the non-pregnant individual, necessitating a higher INR target, which puts mother and child at greater risk of complications during pregnancy and in the postpartum period [3, 7]. Yet even within the cohort of women with mechanical valves at the same location, data and outcomes vary significantly. Biological versus mechanical prosthetic valves carry distinct risks and benefits for both the mother and child, with improved outcomes in women with biological prosthetic valves [7, 8]. Ultimately, research on women with right-sided heart valves is rare, and women with mechanical valves even rarer. This is therefore one of the first case reports of anticoagulation in a pregnant woman with a mechanical pulmonary valve.

Standardizing an approach to anticoagulation in pregnant women with prosthetic heart valves is further complicated by variability in anticoagulation regimens. Both dosage and combination of certain anticoagulation medications vary significantly between studies. This case study demonstrates the importance of an innovative and individualized approach to unique cases. Ideally, goals for future fertility should inform surgical decision-making as to when and what type of valve repair is performed. This approach is limited by real-world circumstances. By extrapolating from what is known about pregnancy and prosthetic heart valves, cardiologists and obstetricians can provide the best outcome for mother and child. Regardless of anticoagulation regimen, regular monitoring of anticoagulation with scheduled blood draws should occur throughout pregnancy and in the postpartum period. Most importantly, non-directive counseling should be utilized from pre-contraception to the postpartum period to balance the patient’s desire for pregnancy with realistic expectations for maternal and fetal outcomes.