14 Chapter 2 Cardiac disease in pregnancy D. L. Adamson, M. K. Dhanjal, C. Nelson-Piercy, R. Collis SYNOPSIS Heart disease and its management in obstetrics Aortic dissection Introduction Ischemic heart disease Physiological changes in pregnancy Arrhythmias Normal fi ndings on examination of the Obstetric anesthetic management of the mother with cardiovascular system in pregnancy cardiac disease Cardiac investigations in pregnancy Anesthetic antenatal assessment and classifi cation Congenital heart disease of mother with cardiac disease Acquired heart disease Anesthetic interventions Endocarditis prophylaxis Anesthetic techniques Heart disease and its management in obstetrics D. L. Adamson, M. K. Dhanjal, C. Nelson-Piercy INTRODUCTION disease has continued to rise in the UK since the early 1980s. The major causes of cardiac deaths over Pregnancies complicated by signifi cant heart disease the last 10 years are cardiomyopathy (predominantly are uncommon in the UK, Europe and the devel- peripartum), myocardial infarction (most commonly oped world. However cardiac disease is now the due to coronary artery dissection), dissection of the leading cause of maternal death in the UK. There thoracic aorta and pulmonary hypertension. In were 44 indirect deaths attributed to cardiac disease the UK, rheumatic heart disease is now rare in in 2000-2002, giving a death rate of 2.2 per 100 000 women of childbearing age and mostly confi ned to maternities. The maternal mortality rate from cardiac immigrants. CCh002-F10129.inddh002-F10129.indd 1144 44/26/2007/26/2007 22:05:44:05:44 PPMM HEART DISEASE AND ITS MANAGEMENT IN OBSTETRICS 15 Women with congenital heart disease are surviv- increase in cardiac pre-load (such as infusion of ing longer thanks to corrective or palliative surgery fl uids), increase in left atrial and pulmonary venous in childhood. They are therefore not uncommonly pressure (such as in mitral stenosis) or increased encountered in pregnancy. These women may have pulmonary capillary permeability (such as in pre- complicated pregnancies. Women with mechanical eclampsia), or a combination of these factors. prosthetic valves face diffi cult decisions regarding In late pregnancy in the supine position, pressure anticoagulation in pregnancy. of the gravid uterus on the inferior vena cava causes Because of signifi cant physiological changes in a reduction in venous return to the heart and a con- pregnancy, symptoms, such as palpitations, and signs sequent fall in stroke volume and cardiac output. such as an ejection systolic murmur are very common Turning from the lateral to the supine position may innocent fi ndings. Not all women with signifi cant result in a 25% reduction in cardiac output. Pregnant heart disease are able to meet these increased physio- women should therefore be nursed in the left or right logical demands. The care of the pregnant and lateral position wherever possible. If the mother has parturient woman with heart disease requires a mul- to be kept on her back, the pelvis should be rotated tidisciplinary approach, involving obstetricians, car- so that the uterus drops to the side and cardiac output diologists and anesthetists, preferably in a dedicated as well as uteroplacental blood fl ow are optimized. antenatal cardiac clinic. This allows formulation of an Reduced cardiac output is associated with a reduction agreed and documented management plan encom- in uterine blood fl ow and therefore in placental per- passing management of both planned and emergency fusion; this can compromise the fetus. delivery. Labor is associated with further increases in cardiac output (15% in the fi rst stage and 50% in the second stage). Uterine contractions lead to autotrans- fusion of 300-500 mL of blood back into the circula- PHYSIOLOGICAL CHANGES tion and the sympathetic response to pain and IN PREGNANCY anxiety further elevate heart rate and blood pressure. Cardiac output is increased more during contractions Blood volume starts to increase by the fi fth week after but also between contractions. The rise in stroke conception secondary to estrogen- and prostaglandin- volume with each contraction is attenuated by good induced relaxation of smooth muscle that increases pain relief and further reduced by epidural analgesia the capacitance of the venous bed. Plasma volume and the supine position. Epidural analgesia or anes- increases and red cell mass rises but to a lesser degree, thesia cause arterial vasodilation and a fall in blood thus explaining the physiological anemia of preg- pressure. General anesthesia is associated with a rise nancy. Relaxation of smooth muscle on the arterial in blood pressure and heart rate during induction, side results in a profound fall in systemic vascular but cardiovascular stability thereafter. Prostaglan- resistance and together with the increase in blood dins given to induce labor have little effect on volume, determines the early increase in cardiac hemodynamics but ergometrine causes vasocons- output. Blood pressure falls slightly but by term has triction and syntocinon can cause vasodilation and usually returned to the pre-pregnancy value. The fl uid retention. increased cardiac output is achieved by an increase in Following delivery of the baby up to 1 L of blood stroke volume and a lesser increase in resting heart may be returned to the circulation due to the relief of rate of 10-20 beats/min. By the end of the second tri- inferior vena cava obstruction and contraction of the mester the blood volume and stroke volume have uterus. The intrathoracic and cardiac blood volumes risen by between 30 and 50%. This increase correlates rise, cardiac output increases by 60-80% followed by with the size and weight of the products of conception a rapid decline to pre-labor values within about 1 h and is therefore considerably greater in multiple of delivery. Transfer of fl uid from the extravascular pregnancies as is the risk of heart failure in heart space increases venous return and stroke volume disease. further. Those women with cardiovascular compro- Although there is no increase in pulmonary capil- mise are therefore most at risk of pulmonary edema lary wedge pressure (PCWP), plasma colloid oncotic during the second stage of labor and the immediate pressure is reduced. The colloid oncotic pressure- postpartum period. All the changes revert quite pulmonary capillary wedge pressure gradient is rapidly during the fi rst week and more slowly over reduced by 28%, making pregnant women particu- the following six weeks but even at a year signifi cant larly susceptible to pulmonary edema. Pulmonary changes still persist and are enhanced by a subse- edema may be precipitated if there is either an quent pregnancy. CCh002-F10129.inddh002-F10129.indd 1155 44/26/2007/26/2007 22:05:44:05:44 PPMM 16 CARDIAC DISEASE IN PREGNANCY NORMAL FINDINGS ON EXAMINATION a lesion which is associated with long-term survival OF THE CARDIOVASCULAR SYSTEM or because they have had successful surgery. Whilst IN PREGNANCY some may not be able to tolerate the hemodynamic changes of pregnancy, the majority will have enough Normal fi ndings on cardiovascular examination may cardiac reserve to carry a pregnancy to term. CHD is include a loud fi rst heart sound with exaggerated infrequently associated with maternal mortality, splitting of the second heart sound and a physiological however, there may be a signifi cant deterioration in third heart sound at the apex. A systolic ejection the maternal condition. These complex patients should murmur at the left sternal edge is heard in nearly all be jointly cared for by obstetricians, obstetric physi- women and may be remarkably loud and be audible cians and cardiologists with expertise in pregnancy all over the precordium. It varies with posture and if and adult congenital heart disease and provide a chal- unaccompanied by any other abnormality it refl ects lenge for such a team. the increased stroke output. Venous hums and mam- mary souffl es may be heard. Because of the peripheral vasodilation the pulse may be bounding and in addi- Pre-pregnancy counseling and assessment tion ectopic beats are very common in pregnancy. Most women with congenital heart disease are known to a cardiologist prior to pregnancy. It is extremely CARDIAC INVESTIGATIONS important that such women are appropriately coun- IN PREGNANCY seled about their individual health risks with preg- nancy. If pregnancy carries an unacceptable risk, this The electrocardiographic (ECG) axis shifts superiorly should be explained and appropriate contraceptive in late pregnancy due to a more horizontal position of advice given. Advising an individual may be diffi cult, the heart. Small Q-waves and T-wave inversion in the particularly those with corrected complex disease, as right precordial leads are not uncommon. Atrial and data remain sparse for pregnancy outcomes following ventricular ectopics are both common. some forms of corrective and palliative surgery. The amount of radiation received by the fetus Maternal risk of pregnancy is assessed by obtain- during a maternal chest X-ray (CXR) is negligible and ing an accurate history, which will defi ne the func- a CXR should never be withheld if clinically indicated tional status, examination and undertaking relevant in pregnancy. Transthoracic echocardiogram is the investigations. This also provides a baseline of the investigation of choice to exclude, confi rm or monitor cardiovascular status, allowing any change occurring structural heart disease in pregnancy. Transesopha- in pregnancy to be objectively