Asian Intensive Care: problems & solutions
International Intensive Care conference, Hong Kong, November 28th-30th 2007
Click here for details

Marcelle Michail, MBBS, FRCA

Valvular disease

Congenital disease

Ischaemic disease

Cardiomyopathy

The latest report on Confidential Enquiries into Maternal Death in the UK (CEMD) was published at the end of 1998, and relates to the years 1994-6. During this period there were 39 maternal deaths classified as directly attributable to cardiac disease.

The pattern of cardiac disease in the pregnant population has changed considerably over the past 40 years. Before 1961 most cardiac deaths were attributable to rheumatic heart disease. In 1994-96 26% cardiac deaths were associated with congenital disease, and 74% with acquired disease.

Understanding the nature of the disease and the normal impact of pregnancy on cardiovascular physiology will enable the obstetric anaesthetist to care for these mothers safely and effectively.

Antenatal assessment: the woman should be under the care of a cardiologist. She should also be seen by the anaesthetist ideally at about 24 weeks gestation and again at 34 weeks. At this time the physiological effects of her pregnancy will be maximal on her disease. Different options for pain relief and appropriate methods of anaesthesia in case of caesarean section should be discussed.

Good communication between the obstetrician, midwives, cardiologist and anaesthetist is essential in the management of these patients. Successive CEMDs have emphasised the importance of good communication in preventing maternal mortality and morbidity.

Physiological effects of pregnancy will have a major effect on the mother with valvular disease. The peak physiological effect is between 28-32 weeks gestation, labour and delivery and the first 12-24 hours postpartpartum.

Low risk:

• Pulmonary/tricuspid disease
• Mitral stenosis NYHA 1 or 2
• Porcine valve

Moderate risk:

• Mitral stenosis with atrial fibrillation
• Artificial valve
• Mitral stenosis NYHA 3 or 4
• Aortic stenosis

High risk:

• Valvular disease resulting in severe pulmonary hypertension
• Valvular disease with severe left ventricular dysfunction i.e EF< 0.4
• Aortic regurgitation associated with Marfans syndrome

Many murmurs in asymptomatic adults are innocent and have no functional significance. They are characteristically:

• Grade 1 or 2 at the left sternal edge
• A systolic ejection pattern
• Normal intensity and splitting of the second heart sound
• No other abnormal sounds
• No evidence of ventricular dilatation or hypertrophy
• No increase in murmur intensity during Valsalva manoeuvre

These murmurs are very common during pregnancy. Echocardiograph is very valuable to rule out structural abnormalities. Exercise testing gives the best indication of physiological reserve when ventricular function appears normal.

• Traditional teaching has proposed that regional anaesthesia is advisable for mitral valve disease with other problems being dealt with using general anaesthesia for operative delivery and opioids for analgesia in labour.
• A more rational approach to managing these patients is to consider the effects that any technique might have on cardiovascular variables, in particular, heart rate and rhythm, preload, after load and myocardial contractility.
• The main requirements for mitral stenosis are to avoid tachycardia, avoid increase in preload, avoid marked decreases in afterload and maintain contractility. In this case there is benefit in the use of a regional technique.
• The main requirements for aortic stenosis are avoid tachycardia, maintain preload and ensure venous return, avoid any reduction in afterload and maintain contractility. In this case the use of a regional technique is less advisable because of the concern regarding the possibility of decrease in afterload in the face of a fixed cardiac output.

As a result of early palliative or more complete repair of congenital heart disease (CHD), a number of women with cyanotic CHD reach the child-bearing age. The risks of maternal complications and neonatal mortality and morbidity are high.

Antenatal problems which can endanger maternal life are severe hypoxaemia, arrythmias, congestive cardiac failure and secondary erythrocytosis leading to blood hyperviscosity and diminished tissue oxygenation.

Management during late pregnancy include bed rest, oxygen administration, thromboembolism prophylaxis.

Case reports have shown that both operative or vaginal delivery were managed successfully with regional or less frequently general anaesthesia. Invasive monitoring especially invasive arterial pressure monitoring is recommended.

Eisenmenger’s syndrome is a consequence of various CHD with direct connections between systemic and pulmonary circulation such as septal defect or ductus arteriosus.

Pulmonary artery pressure reaches or exceeds systemic arterial pressure.

The condition is associated with a high mortality rate ranging from 30% to 50%, with most patients dying after delivery. In the latest CEMD the typical picture that emerges from all deaths from pulmonary hypertension is one of clinical deterioration and increased pulmonary resistance soon after delivery.

Maternal outcome depends on early hospitalisation, severity of pulmonary vascular disease and intensive medical care in the highly vulnerable period after delivery.

Myocardial infarction during pregnancy is rare with an estimated incidence of 1:10000 pregnancies.

Risk factors include cigarette smoking, drug abuse such as "crack"cocaine and the increasing trend towards childbearing later in life.

The demand placed on the myocardium by pregnancy and delivery can precipitate angina, infarction and cardiac failure in patient with pre-existing ischaemic heart disease. The hypercoagulable state can also contribute to coronary artery thrombosis.

Many of the symptoms and signs of pregnancy can mimic heart disease confusing the diagnosis, e.g. dyspnea on exertion, orthopnea, and chest discomfort and peripheral oedema. ECG may demonstrate sinus tachycardia, left axis deviation, ST segment depression, flat or inverted T wave and Q waves in lead III.

However paroxysmal nocturnal dispense, exercise-induced chest pain and persistent dysrrhysmias should merit further investigation.

Echocardiogram is the preferred non-invasive investigation in the parturient.

Each contraction augments the already increased cardiac output increasing cardiac work and oxygen demand. Maternal stress and pain causing a reflex tachycardia and increase systemic vascular resistance will further increase myocardial oxygen demand.

Regional analgesia will reduce myocardial oxygen demand and should always be considered. Epidural should be instituted incrementally and fentanyl used to supplement a low concentration of local anaesthetic in order to minimise the degree of cardiovascular instability.

In patient with severe disease, caesarean section is usually the safest mode of delivery to avoid the haemodynamic stresses of labour. The anaesthetic choice must be made on individual bases.

If regional technique is acceptable, the slower onset of epidural analgesia with consequent slow haemodynamic change is preferable to the more rapid response to intrathecal analgesia. Combined spinal epidural combine the dense and relatively cardiostable pelvic anaesthesia with a carefully titrated thoraco-lumbar block.

General anaesthesia is indicated in cases of unstable angina and congestive cardiac failure where orthopnea prevents the supine position for surgery. The patient with compromised left ventricle does not tolerate the standard rapid sequence induction and the haemodynamic response to laryngoscopy. A technique using invasive haemodynamic monitoring and a high dose alfentanil as the sole induction agent has been shown to provide stability in these patients.

Ergometrin should be avoided and syntocinon should be administered slowly to prevent myocardial depression

These patients should be nursed in high dependency unit to allow invasive monitoring and oxygen administration in the first 48 hours post delivery.

The risk of thromboembolism is higher in those patient and anticoagulant, TED stockings and early mobilisation should be employed.

Regular medication should be treated as soon as possible and their effect on breast feeding thought of.

Defined as primary disease of the myocardium. It may arise before or after the patient conceives. It is classified by the World Health Organisation into three types: restrictive, hypertrophic and dilated.

Mimics constrictive pericarditis with impaired ventricular filling and poor contractility. Management in labour includes limiting further reduction in myocardial contractility and maintaining cardiac filling pressure. This may be achieved with epidural block.

This condition often improves during pregnancy as blood volume increases and the diagnosis may be missed. Anxiety, hypovolaemia and strenuous exercise may increase infundibular spasm by increasing sympathetic tone.

Best managed in labour with a slow incremental epidural. Case report shown caesarean has been performed under epidural and general anaesthesia.

More on HOCM

This is a variant of dilated cardiomyopathy, with an incidence of 1:3000- 1:4000 pregnancies. Diagnostic criteria include:

1. Development of cardiac failure in the last month of pregnancy or within 5 month of delivery
2. Absence of specific aetiology for cardiac failure
3. Absence of demonstrable cardiac disease before the last month of pregnancy

The presenting symptoms are: maternal dyspnea, cough, orthopnea and palpitation.

Management: the aim is to minimise further decreased in cardiac performance. Both epidural and general anaesthesia has been performed successfully.

Prognosis: 50% of patient recover good ventricular function within 6 months of delivery, but 50% have persistent cardiomegaly. The latter group have a mortality of 80%.

More on peripartum cardiomyopathy

© Marcelle Michail September 1999

Forthcoming BASIC courses: February - London, Kuala Lumpur; March - Hawkes Bay, Sun City; April - Beijing, Brisbane
Click here for details

©Charles Gomersall, March, 2007 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
Copyright policy    Contributors