The use of pulsatile perfusion during aortic valve replacement in pregnancy

Indications for Cardiopulmonary Bypass During Pregnancy and Impact on Fetal Outcomes

Background: Cardiac operations in pregnant patients are a challenge for physicians in multidisciplinary teams due to the complexity of the condition which affects both mother and baby. Management strategies vary on a case-by-case basis. Feto-neonatal and maternal outcomes after cardiopulmonary bypass (CPB) in pregnancy, especially long-term follow-up results, have not been sufficiently described. Methods: This review was based on a complete literature retrieval of articles published between 1991 and April 30, 2013. Results: Indications for CPB during pregnancy were cardiac surgery in 150 (96.8 %) patients, most of which consisted of valve replacements for mitral and/or aortic valve disorders, resuscitation due to amniotic fluid embolism, autotransfusion, and circulatory support during cesarean section to improve patient survival in 5 (3.2 %) patients. During CPB, fetuses showed either a brief heart rate drop with natural recovery after surgery or, in most cases, fetal heart rate remained normal throughout the whole course of CPB. Overall feto-neonatal mortality was 18.6 %. In comparison with pregnant patients whose baby survived, feto-neonatal death occurred after a significantly shorter gestational period at the time of onset of cardiac symptoms, cardiac surgery/resuscitation under CPB in the whole patient setting, or cardiac surgery/resuscitation with CPB prior to delivery. Conclusions: The most common surgical indications for CPB during pregnancy were cardiac surgery, followed by resuscitation for cardiopulmonary collapse. CPB was used most frequently in maternal cardiac surgery/resuscitation in the second trimester. Improved CPB conditions including high flow, high pressure and normothermia or mild hypothermia during pregnancy have benefited maternal and feto-neonatal outcomes. A shorter gestational period and the use of CPB during pregnancy were closely associated with feto-neonatal mortality. It is therefore important to attempt delivery ahead of surgery/CPB or to defer surgery till late pregnancy.

Surgical management of valvular heart diseases in pregnancy

Heart disease in pregnancy remains one of the important causes for maternal and fetal mortality and morbidity. Cardiac surgery undertaken in pregnancy presents specific additional issues for both the mother and fetus; especially cardiopulmonary bypass and the factors associated with it. Successful outcome of cardiopulmonary bypass surgery during pregnancy depends upon the multidisciplinary management of the patient, which is frequently under reported from the developing world. We present our experience of two cases where cardiopulmonary bypass surgery for cardiac valve replacement was successfully performed during pregnancy without any maternal or fetal mortality. A review of published literature is also undertaken in order to present evidence based recommendations for undertaking such procedures in pregnancy.

Emergency tricuspid valve replacement during pregnancy

A 36 year-old intravenous drug user at 19 weeks' gestation required emergency tricuspid valve replacement for severe tricuspid regurgitation and cardiogenic shock refractory to medical therapy. Normothermic, pulsatile, high-flow, and pressure cardiopulmonary bypass (CPB) was used in the absence of fetal monitoring. Ten days postoperatively, the patient miscarried. She was discharged from hospital two months following surgery. High-flow (> 3.0 L/min(2)), high-pressure (> 70 mmHg), normothermic CPB using pulsatile flow and blood cardioplegia is thought to offer the best outcome to the fetus, although data to support these claims are not compelling.

[Pregnancy and cardiac surgery with cardiopulmonary bypass]

Heart disease during pregnancy necessitating cardiac surgery is potentially increasing maternal and fetal morbidity and mortality. Most patients know about their heart disease long before conception however the relation between the deteriorating cardiac function and the perinatal complications is not emphasized. Best possible results can be achieved by providing preconception counseling for cardiac patients. Consequently, heart-surgery can be performed before pregnancy thereby the maternal risk is lower and fetal loss or induced abortion can be avoided. The pregnant state is not optimal for cardiac surgery as the principal interest of the mother and the fetus is different. Cardiac surgery should be reserved only for saving the patient's life when medical therapy proves insufficient or when conservative management leads to acute heart failure. The multidisciplinary approach, correct risk assessment, diagnosis, operative indication, timing along with appropriate anaesthesia, extracorporeal circulation and alert monitoring of the uterine activity and fetal heart rate patterns make the intervention technically safe. Fetal monitoring is inevitable for prompt correction of operative conditions in case of impending hypoxemia. The perioperative fetal risk can be reduced by applying normothermia, high mean arterial pressure and cardiac index during the intentionally shortest intervention. Cardiac operation with cardiopulmonary bypass during pregnancy has become a relatively safe procedure for the mother but not for the baby.

Emergency redo mitral valve replacement in a pregnant woman at third trimester: case report and literature review

Pregnancy carries significant physiological changes that demand more cardiac output, so structural cardiac disease can cause life-threatening complications. A woman had rheumatic mitral stenosis and underwent mitral valve replacement (MVR) with bioprosthesis 8 years prior to admission. She presented with dyspnea and leg edema at 30 weeks of gestation. Severe mitral stenosis caused by xenograft failure was noted on echocardiography. Management was conservative until a sudden onset of hemodynamic compromise requiring emergency redo MVR under normothermic cardiopulmonary bypass with intra-aortic balloon pump. Monitoring of fetal heartbeat and uterine contractions showed no significant abnormalities and the woman gave birth to a full-term baby by Cesarean section with postoperative warfarin therapy.

Heart Disease in Pregnancy 4

Ischemic heart disease and cardiomyopathy in pregnancy are both rare. Therefore, a high level of suspicion is required by the obstetric caregiver when women complain of the often vague symptoms that are indicative of these conditions. Early diagnosis, consultation with a cardiologist, and aggressive therapy are the keys to reducing morbidity and mortality. Women who suffer myocardial infarction in pregnancy should be stabilized, and delivery within the first two weeks post event should be avoided if possible. Women who completely recover from peripartum cardiomyopathy can be reassured when considering future pregnancies. Pregnancy should be considered contraindicated in women with Class H diabetes, and efforts should be made to establish reliable contraception. This is the fourth in a series of five articles reviewing in detail the assessment and management of specific cardiac disorders in pregnancy.

Acquired Heart Disease in Pregnancy

The incidence of rheumatic heart disease in most industrialized countries is decreasing. Those women who have regurgitant lesions will commonly experience an improvement in symptoms, and therapy is required only in the most severe cases. Women with mild to moderate stenotic lesions can usually expect a good outcome to pregnancy, but women with severe stenotic lesions require close monitoring by both their obstetricians and their cardiologists, especially during the third trimester, labour and delivery, and the early postpartum period. This is the third in a series of five articles reviewing in detail the assessment and management of specific cardiac disorders in pregnancy.

Cardiopulmonary bypass and mitral valve replacement during pregnancy

Gravid patient cardiopulmonary bypass remains a high-risk procedure with regard to fetal preservation. Maternal mortality is similar to that of the nonpregnant female at 1.5-5%. However, fetal mortality remains high at 16-33%, with an average of 19% over the past 25 years, with no correlation to gestational age. Teratogenesis is a major consideration in the first trimester. Variations in the timing of surgical intervention, gestational age, maternal health status, type of procedure, pre- or postorganogenesis, perfusion protocol, and pharmaceutical therapy are all factors that can influence fetomaternal outcome. In this report, we present a literature review along with our experience of a 26-year-old female who developed complications with her pregnancy at approximately 17 weeks gestation, with adverse neurological sequelae. The patient was 152 cm in height and weighed 48 kg, with a calculated body surface area of 1.40 M2. She had no prior history of cardiac disease and, upon admission to our institution, presented with a declining health status in pulmonary edema and was treated medically, with an ultimate requirement for mitral valve replacement. The total cardiopulmonary bypass time was 99 min with an aortic crossclamp time of 83 min. The literature, as expected, is limited to case reports and reviews since a controlled clinical trial during pregnancy is nonexistent, using extracorporeal circulation. This greatly challenges the medical staff in managing such difficult cases, with an incidence of heart disease during pregnancy of 1.2-3.7%.

The effect of maternal hypothermic cardiopulmonary bypass on fetal lamb temperature, hemodynamics, oxygenation, and acid-base balance

OBJECTIVE

To evaluate fetal-maternal temperature relationship and fetal cardiovascular and metabolic response during maternal hypothermic cardiopulmonary bypass in pregnant ewes.

METHODS

Cardiopulmonary bypass was instituted in 9 pregnant ewes, reaching 2 different levels of maternal hypothermia: 24 degrees C to 20 degrees C (deep hypothermia) in group A (5 cases) and less than 20 degrees C (very deep hypothermia) in group B (4 cases). Hypothermic levels were maintained for 20 minutes, then the rewarming phase was started. Fetal and maternal temperature, blood pressure, heart rate, electrocardiogram, blood gases, and acid-base balance were evaluated at different levels of hypothermia and during recovery.

RESULTS

Fetal survival was related to maternal hypothermia: all group A fetuses survived, while 2 of 4 fetuses of group B in which maternal temperature was lowered below 18 degrees C died in a very deep acidotic and hypoxic status. Maternal temperature was always lower than fetal temperature during cooling; during rewarming the gradient was inverted. The start of cardiopulmonary bypass and cooling was associated with transient fetal tachycardia and hypertension; then, both fetal heart rate and blood pressure progressively decreased. The reduction of fetal heart rate was of 7 beats per minute for each degree of fetal cooling. Deep maternal hypothermia was associated with fetal alkalosis and reduction of Po(2). Very deep hypothermia, in particular below 18 degrees C, caused irreversible fetal acidosis and hypoxia.

CONCLUSIONS

Deep maternal hypothermic cardiopulmonary bypass was associated with reversible modifications in fetal cardiovascular parameters, blood gases, and acid-base balance and therefore with fetal survival. On the contrary, fetuses did not survive to a very deep hypothermia below 18 degrees C.

Beating heart aortic valve replacement in a pregnant patient

A 23-year-old woman with a history of previous bileaflet mechanical aortic valve replacement presented in acute heart failure at 27 weeks of gestation. Transthoracic echocardiography (TEE) demonstrated minimal leaflet excursion consistent with valve thrombosis. The patient underwent emergent surgery with normothermic cardiopulmonary bypass (CPB), and beating-heart technique for valve replacement. This novel strategy for aortic valve replacement is being presented as being particularly useful in pregnant patients whose fetuses are at risks of hypothermia, hemodilution, and hyperkalemia during CPB.