Chapter 15 Cardiovascular, respiratory, haematological, neurological and gastrointestinal disorders in pregnancy
CARDIOVASCULAR COMPLICATIONS IN PREGNANCY
It will be recalled that pregnancy places an increased strain on the heart because of the increased rate and stroke volume. The burden on the heart reaches its maximum at about the 28th week and continues into the puerperium. If a pregnant woman has heart disease, the increased strain may affect her wellbeing.
At present, in the developed countries between 0.2 and 0.5% of pregnant women have heart disease. In 30% of cases a woman has mitral valve disease; in 20% ventricular septal defect; in 15%, atrial septal defect; in 15%, aortic stenosis; and in the remainder, other defects.
Diagnosis
In most cases the diagnosis has been established before the pregnancy, but the doctor should auscultate the woman’s heart at the first antenatal visit. Any suspicious signs, particularly a diastolic or loud systolic murmur, should lead to referral to a cardiologist.
Management in pregnancy
The initial assessment of the pregnant woman should be made in conjunction with a cardiologist, after which the medical management of the pregnancy can be carried out by the attending doctor, the patient being reviewed by the cardiologist at intervals. The aims of management are:
Factors that predispose to heart failure include anaemia, infections (particularly urinary tract infections) and the development of hypertension. If any of these are found, treatment should be started.
The woman’s cooperation, and that of her family, should be obtained. Her daily activities should be evaluated and changes suggested if this is appropriate.
The patient should be seen at intervals of no more than 2 weeks up to the 28th week of pregnancy, and thereafter weekly by a doctor (if it causes less stress on the woman, it could be her GP in collaboration with the obstetrician and the cardiologist). At each visit cardiac function is assessed by inquiring about breathlessness on exertion, or if she has a cough or orthopnoea. Her lungs are auscultated to detect rales.
Many cardiologists place pregnant women in categories suggested by the New York Heart Association, and the management is planned according to this. Initially most pregnant women are in class 1 or 2, but during pregnancy in 15–55% some degree of cardiac decompensation occurs.
Class 1
The patient has no symptoms, although signs of cardiac damage are present. She can undertake all physical activities. In this class, no additional treatment is needed.
Class 2
The woman is comfortable at rest, but ordinary physical exertion usually causes fatigue, palpitations and, occasionally, dyspnoea. Most patients in this class do not require treatment, but if the woman’s social conditions are unfavourable or if signs of a deterioration in cardiac reserve occur, she should be admitted to hospital.
Class 3
Less than ordinary physical exertion causes dyspnoea and fatigue, although the patient is comfortable when resting. Most women in this class should be admitted to hospital for rest, but home conditions and responsibilities have to be assessed and help provided if needed.
Class 4
Women in this class are seriously ill. The patient is breathless even when resting. Hospital admission is mandatory.
Heart failure
Should the woman develop heart failure the principles of treatment are no different from those of non-pregnant women. Digoxin is given to control the heart rate and increase the time for blood flow into the left ventricle. Diuretics (such as furosemide) are given when pulmonary oedema is present. There is no consensus as to whether women who are not in cardiac failure should be given prophylactic digoxin, but most experts agree that if the woman is at risk of atrial fibrillation or has mitral heart disease and an enlarged left atrium, digoxin is indicated.
Management during childbirth
Most women who have heart disease have an easy, spontaneous labour and there is no indication for inducing labour on account of the cardiac condition. During labour the patient should be nursed either on her side or well propped up, as compression of the aorta in the supine position may cause marked hypotension. The woman’s fluid balance and her pulse rate should be checked at intervals. If the woman requires anaesthesia, an epidural blockade is the preferred choice as it decreases sympathetic activity, and reduces both oxygen consumption and variations in cardiac output.
Delay in the second stage of labour should be rectified by the use of forceps or vacuum extractor, but there is no need for prophylactic instrumental delivery. The third stage is conducted in the same way as in non-cardiac patients, and active management using Syntocinon is safe, unless the woman is in heart failure. The accoucheur should always bear in mind that in general, women with cardiac disease tolerate postpartum haemorrhage poorly.
The risks and management of specific cardiac conditions are summarized in Table 15.1.
Table 15.1 Management of specific cardiac conditions
The puerperium
The burden on the heart continues into the puerperium. For the first 24–48 hours the patient must be constantly observed for signs of decompensation. She should then be closely monitored for the first few days, and additional support should be made available when she returns home.
Prognosis for mother and baby and for future pregnancies
The prognosis for the mother is dependent on the underlying aetiology. With good antenatal care the risk to the mother or fetus if the disease is mild is not usually increased during the current pregnancy. Women with significant impairment of cardiac function should be dissuaded from further pregnancies until the condition of the heart has been assessed and further treatment, including surgery, discussed.
VENOUS THROMBOEMBOLISM IN PREGNANCY
Venous thromboembolism (VTE) affects between 50 and 60 pregnant or postpartum women per 100 000, with a mortality rate of 1 per 100 000 maternities. It is highest in women aged over 39, the mortality rate being 1 per 3300. The prevalence of VTE is equally distributed throughout pregnancy, but the day-by-day risk is greatest in the immediate puerperium. The major risk factors include caesarean section, obesity, prolonged immobility, pre-eclampsia, current infection, previous VTE and familial thrombophilia.
Treatment of a pulmonary embolus during pregnancy consists of unfractionated heparin (UH), initially intravenously (40 000 U/day by continuous infusion in normal saline) to obtain a concentration of 0.6–1.0 U/mL. Once full heparinization has been obtained for 3–7 days, the infusion may be replaced by calcium heparin given subcutaneously. A deep vein thrombosis (DVT) is treated either with UH if delivery or surgery is imminent, or low molecular weight heparin (LWMH) given subcutaneously. UH is substituted for LMWH 24–36 hours prior to delivery. UH is suspended once labour is established or 6 hours before surgery, and recommenced 2–6 hours after vaginal or caesarean delivery. If the woman has a high risk of VTE antenatally (includes recurrent VTE, previous idiopathic VTE or previous VTE and a strong family history of VTE) she may be given LMWH prophylaxis throughout pregnancy and for 6 weeks postpartum (see also postpartum thromboembolism, p. 186).
ANTIPHOSPHOLIPID SYNDROME
Antiphospholipid syndrome (APS) is associated with early-onset pre-eclampsia, intrauterine fetal growth restriction, preterm birth, miscarriage, fetal death and venous thromboembolism. Diagnosis requires at least one of the clinical criteria and one of the laboratory criteria (see Box 15.1). Women who have suffered from clinical complications should be screened and referred for specialist evaluation.
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