Congenital heart disease and pregnancy

Michael G. Earing, MD, Adult Congenital Heart Disease Program, Herma Heart Center, Children's Hospital of Wisconsin; assistant professor, Pediatrics (Cardiology), Medical College of Wisconsin

The incidence of congenital heart disease (CHD) in the United States is estimated to be 0.5-0.8 percent, or 32,000 new cases per year. This does not include bicuspid aortic valves, occurring in 2-3 percent of live births. As a result of medical and surgical advances, 85 percent of children born with CHD now are surviving into adulthood. This has resulted in a steady increase in the number of females with CHD reaching childbearing age. In fact, CHD now is the predominant form of heart disease encountered during pregnancy in developed countries.

CHD does not preclude a successful pregnancy, however the hemodynamic changes that occur during pregnancy can have adverse consequences for the pregnant woman and her fetus. These complications may include heart failure, arrhythmias, stroke and even death of the mother or fetus. During a normal pregnancy, there is a 20-30 percent increase in red blood cell mass and a 30-50 percent increase in plasma volume, resulting in an increase in the total blood volume. In addition, the heart rate increases by 10 beats/minute and there is a reduction in both the systemic and pulmonary vascular resistance. As a result of these changes, the cardiac output steadily increases until the 32nd week, where it plateaus at 30-50 percent above the prepregnancy level. During labor and delivery, there are further hemodynamic changes. With uterine contractions, an additional 300-500 ml of blood can enter the circulation. In addition, the heart rate and blood pressure at the time of labor and delivery also is increased. These changes result in the cardiac output at the time of delivery being nearly 80 percent higher than the prepregnancy level. Immediately following delivery, relief of caval compression results in improved venous return and there will be spontaneous diuresis. However, it will take two-to-four weeks for the hemodynamics to return to baseline.

The task of advising females with CHD in regard to the safety of pregnancy needs to be an intricate part of all adult congenital heart disease and pediatric cardiology programs. Studies of pregnancy outcomes in women with CHD have shown that one can expect a favorable maternal and fetal outcome in most cases. However, because of the hemodynamic changes of pregnancy, certain conditions have been shown to carry significant risk to both the mother and fetus. In general, fixed obstructive cardiac lesions with severe obstruction (mitral and aortic valve stenosis, coarctation of aorta, hypertrophic cardiomyopathy) and those with pulmonary hypertension (defined as pulmonary artery pressure ¡Ý 3⁄4 systemic) are poorly tolerated and are considered contraindications to pregnancy. In contrast, regurgitant lesions and lesions with resting left to right shunts in the setting of normal pulmonary artery pressure typically are well tolerated. Other cardiac conditions in which pregnancy should be avoided include class III-IV congestive heart failure due to systemic ventricular dysfunction and Marfan Syndrome with a dilated aortic root of 40 mm.

Risk stratification and counseling of women with CHD is best accomplished prior to conception and can be obtained by performing a detailed cardiovascular history and exam, 12-lead ECG and a transthoracic echocardiogram. In counseling, the following six areas need to be considered: the underlying cardiac lesion; maternal functional class; the possibility of further palliative or corrective surgery prior to conception that may improve hemodynamics such as in the setting of aortic valve stenosis; additional associated risk factors that may complicate a pregnancy such as preexisting arrhythmias, prosthetic valves, chronic anticoagulation or use of other teratogen drugs such as Ace inhibitors; maternal life expectancy and ability to care for her child; and finally, the risk of congenital heart disease in the child.

Classically, patients have been stratified into low, intermediate or high-risk groups based on the nature of their lesion. However, over the last 10 years it has become increasingly evident that maternal status defined by New York Heart Association (NYHA) functional class is highly predictive of both maternal and fetal prognosis. In the largest published series, the maternal mortality rate for women in NYHA class I or II with CHD was less than 1 percent. However, with advanced NYHA class, the maternal mortality rate increased to 7 percent. Similarly in this same study, the maternal functional class also was highly predictive of fetal outcome with a fetal mortality for women in NYHA class IV of 30 percent.

Thus, management of pregnant women with CHD depends on both the underlying cardiac condition and their maternal functional class. In general, women considered to have a low risk lesion and who are in NYHA class I prior to pregnancy are followed with fetal ultrasound and fetal cardiac ultrasound and can be safely delivered in a community hospital.

With few exceptions, vaginal delivery with a facilitated second stage of labor (forceps delivery or vacuum extraction) is the preferred route of delivery in patients with CHD. Cesarean delivery is indicated when obstetrics reasons are present, in those patients on coumadin, acute aortic dissection, Marfan syndrome with a dilated aortic root, and those with severe pulmonary hypertension and severe cardiac obstructive lesions. Labor should be conducted in the left lateral decubitus position to attenuate hemodynamic fluctuations associated with contractions. Epidural anesthesia with adequate volume preload is the preferred method of pain control in women with CHD, in particular in patients with single ventricle physiology. The American Heart Association currently does not recommend endocarditis prophylaxis for women with CHD expected to have an uncomplicated delivery. However, many centers with significant experience with CHD and pregnancy continue to recommend endocarditis prophylaxis given it often can be difficult to predict which delivery may become complicated.

Pregnant women with high risk lesions and are in NYHA class III-IV, should be managed in a high-risk pregnancy center experienced with CHD by a multidisciplinary team composed of obstetrics, cardiovascular anesthesia, cardiology and pediatrics. Once fetal maturity is confirmed, elective induction of labor often is preferred. Invasive hemodynamic monitoring in these patients with intraarterial monitoring with or without a central venous catheter often is helpful and allows for rapid intervention if complications arise. In the immediate postpartum period, there continues to be large fluctuations in hemodynamics. As a result, postpartum, these patients should be monitored for a minimum of 72 hours in the hospital.

Women with CHD now comprise the majority of patients with heart disease seen in pregnancy, accounting for 80 percent of all patients. In general, pregnancy is well tolerated in patients with CHD. However, for some women with particularly high-risk lesions and poor functional class, pregnancy poses significant risk for cardiovascular complications including premature death. As result, pre-conception counseling and risk stratification is mandatory and should be done in all women with CHD of child bearing age. 

Preventive Cardiology Clinic begins

The Preventive Cardiology Clinic is a subspecialty clinic in the Herma Heart Center focusing on children with risk factors for early coronary artery disease. It started nearly a year ago and uses a multidisciplinary team approach including a pediatric cardiologist, a nurse practitioner and an exercise physiologist. The team sees children who have a family risk of early coronary artery disease such as hypertension or hyperlipidemia. Other risk factors include children with congenital heart disease who have dietary or exercise restrictions or need basic healthy lifestyle changes and adults with congenital heart disease who have activity restrictions or dietary limitations. The clinic has experienced good success with tailored exercise programs and nutrition counseling and has prevented medication therapy and even discontinued medications for some patients.

For more information, contact Pamela Cava, DO, Herma Heart Center, at (414) 266-2380 or the Gurnee, Ill. office at (847) 662-4380 

Mediapleural tubes

L. Eliot May PA-C, senior physician assistant, Herma Heart Center, Children's Hospital of Wisconsin.

Recently, you may have noticed the terms "mediapleural," "bowflex" or "wine glass" when referring to chest tubes. Traditionally, mediastinal chest tubes are placed medially, beneath the lowest part of the median sternotomy incision. Sometimes singly, sometimes in pairs, pleural chest tubes traditionally have been inserted laterally. In an effort to minimize the number of tubes and the number of chest tube scars, mediapleural tubes have been utilized. These tubes are inserted in the location traditionally used for mediastinal tubes. The tubes have been modified by adding extra holes proximally. The tip of the tube is fed into the pleural space, to the apex of the right or left hemithorax. The more proximal part of the tube is within the mediastinum. With the mediapleural tubes, both the pleural space and mediastinum are drained. Special care must be observed when removing these tubes to prevent pneumothorax. Vaseline gauze is used to seal the hole, just as with removal of traditional pleural tubes.

How do you know if your patient has traditional mediastinal tubes or mediapleural tubes? Look at the chest X-ray. If the tip of the tube is outside of the mediastinum, near the apex of the right or left hemithorax, it is a mediapleural tube.

These unique tubes are used when the pleural space is opened during surgery, in patients who it is determined will likely not need pleural drainage for an extended time. Sometimes these tubes are placed to drain potential pleural effusions, often in patients with tetralogy of Fallot repair, atrioventricular canal repair or certain other patients.

Pediatric heart transplant versus staged reconstruction operations as primary treatment for hypoplastic left heart syndrome

Erin Fritzinger, RN, Pediatric Intensive Care Unit, Children's Hospital of Wisconsin.

Hypoplastic left heart syndrome (HLHS) occurs in one out of every 4,000 to 6,000 births. It is the second most common congenital heart defect presenting in the first week of life. The success of congenital heart surgery since beginning 50 years ago is tremendous. Life expectancy was a few weeks or months and now is in the teens and 20s.

The first heart transplant was Baby Fae in 1984. Transplant can be seen as a treatment option with good outcomes for infants with heart failure or complex cardiac defects. Transplant as a primary treatment was introduced in the early 1980s when surgical results with staged reconstruction was sub-optimal. One- and five-year survival rates are high – 75 and 65 percent, respectively, with survival half-life greater than 10 years. Transplant is not a cure and after transplant, infection or rejection can occur anytime, but is less likely after one year. Transplant is offered as therapy for some types of congenital heart disease. A baby who has a heart transplant receives a fully functioning four-chamber heart, rather than reconstructing the baby's single ventricle heart. There are many disadvantages of transplant, including limited available donors, a lifetime of immunosuppression and the difficulties of late complications such as graft vasculopathies and myocardial hypertrophy, risks of cancer (especially of the bloodstream), hyperlipidemia, renal dysfunction and hypertension. For narrowing of the coronary arteries, retransplant usually is the only treatment. The risk is 17 percent at fives years but recent era (after 1997) have less coronary artery diease and fewer complications due to newer immunosuppression medications. Nutrition can be a factor with poor growth, which leads to increased immunosupression and antibody titers not increasing with age compared to a normal child. Transplant can't be a primary strategy for complex congenital heart disease until a suitable nonhuman source of donor organs is available with provision of complete immune tolerance by the recipient.

Staged reconstruction has the advantage of being available at the time of birth and there is no need for immunosupression. Current survival can be expected to be 90 percent, decreasing the advantage of transplant. Reasons for improved survival rates are refinements in surgical technique and in pre/post-surgical management of children. One reason for improved outcomes in stage one of the Norwood procedure with a BT shunt has been a better understanding of single ventricle physiology, which involves balancing cardiac output to systemic and pulmonary ciruclations. Another reason for improved outcomes is improved physiologic montoring in the immediate postoperative period that allows early intervention when an infant status is changed. Disadvantages of staged repair are the numerous operations, dependence on the right ventricle for systemic circulation and side effects of the Fontan circulation over a lifetime.

Heart transplantation can be an option for children who have had staged palliative reconstruction and their hearts have failed. Unfortunately, some of these children may die waiting for a suitable heart. There are not enough donors to meet the need. The future of these children will depend on advances in mechanical heart development (Berlin heart) and xenotransplant-cross species.

Herma Heart Center hires new cardiologist

Luke Lamers, MD, is a pediatric cardiologist in the Herma Heart Center at Children's Hospital of Wisconsin and an assistant professor of Pediatrics (Cardiology) at the Medical College of Wisconsin. He joined Herma Heart Center in July 2005 and has an interest in congenital heart disease, interventional catheterization and cardiac critical care.

A graduate of the Medical College of Wisconsin, Milwaukee, he completed a residency in Pediatrics at The Ohio State University-Columbus Children's Hospital, Columbus, Ohio, and recently completed a fellowship in Pediatric Cardiology at the University of Michigan-Mott Children's Hospital, Ann Arbor, Mich. He is board certified in Pediatrics.