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Maternal Cardiology

Heart Disease in Women

Cardiovascular disease is the leading cause of death in women yet most women believe that they are more likely to die from breast cancer than from heart disease. Women usually develop heart disease 10 years later than men, but this "advantage" is lost in Maori women and in women who develop diabetes.

Women are more likely to present with atypical symptoms but central chest tightness remains the most common presenting symptom.

Early research suggests that women delay in presenting for the diagnosis of both angina and acute myocardial infarction and that the delay may be due partly to lack of awareness of their risk of heart disease but also to prior experience of more severe pain surrounding menstruation and child birth. Fewer women attend cardiac rehabilitation despite a demonstrated 25% improvement in survival. The risk of stroke is higher in women than men, with hypertension the leading underlying cause. Rates of cardiovascular disease in women are increased after menopause but unfortunately hormone replacement therapy increases the risk of heart attack and stroke.

There is a tremendous opportunity in both general and cardiology practice to improve the awareness of women as to their risk of cardiovascular disease, to increase diagnostic rates and to actively manage their risk factors.

Maternal Heart Disease in Pregnancy

Heart disease is the second most common medical cause of maternal death in pregnancy after pre-eclampsia. In New Zealand valvular heart disease remains the main problem but as the maternal population ages there are an increasing number of women with coronary disease in pregnancy.

Pregnancy is associated with major changes in the maternal cardiovascular system. The increasing heart rate, falling blood pressure and peripheral vascular resistance and a consequent rise in cardiac output begins at around six weeks gestation, rises rapidly in the second trimester and peaks at 32 weeks gestation. Cardiac output rises by 50% in a single pregnancy and further with each contraction whilst in labour. The blood pressure begins to slowly rise at 32 weeks gestation and will rise more rapidly in all women over the first three days post partum.

As part of a normal pregnancy, women will often feel more short of breath and notice an increased frequency of ectopic beats. An ejection systolic murmur at the left sternal edge is usually audible in all healthy pregnancies from six weeks gestation and reflects the increase in blood flow in the heart.

All women should have their blood pressure checked and heart carefully auscultated early in pregnancy. Careful blood pressure control in the first 20 weeks, whilst the placenta is developing, with the diastolic blood pressure less than 90mmHg will significantly reduce the risk of developing pre-eclampsia later in the pregnancy. Any diastolic murmur is abnormal and systolic murmurs need to be evaluated clinically and if necessary by echocardiography to exclude valvular or congenital lesions. Unexpected shortness of breath or reduction in exercise tolerance should be carefully assessed.

Obstructive lesions (aortic and mitral stenosis, hypertrophic cardiomyopathy and coarctation of the aorta) are generally poorly tolerated in pregnancy whilst regurgitant valvular disease and intracardiac shunts are usually well tolerated providing left ventricular function is adequate and there is no pulmonary hypertension. Women with prosthetic valves are particularly high risk with only about 11% of conceptions in women on Warfarin resulting in a live baby. Maternal stroke risk is also significantly increased in women with prosthetic valves.

The risk of aortic dissection is significantly increased in pregnancy and the puerperium particularly in women with collagen vascular diseases such as Marfan's syndrome. With all congenital conditions the risk of inheritance to the foetus should also be considered.

Arrhythmias, particularly SVT, present frequently in pregnancy. These often require treatment because of the risk of reduced placental perfusion with maternal hypotension.

All drug therapy given to pregnant women needs to be assessed for its risk to the foetus, the changing drug clearance as the pregnancy advances and readjusted postpartum. Warfarin, ACE Inhibitors, Angiotensin 2 blockers and statins are contraindicated from 6 weeks gestation because of foetal toxicity. Atenolol is relatively contraindicated because of associated growth retardation not seen with other beta-blockers. Warfarin can be given from 13 weeks gestation until before delivery but is associated with an increased risk of foetal bleeding. Anticoagulation should never be stopped in a pregnant woman without discussion with her cardiologist as pregnancy is a very high risk time for valve thrombosis and stroke.

The optimal management of pregnant women with heart disease involves a careful evaluation of the cardiac abnormality as early as possible, and preferably pre-pregnancy, by the appropriate Lead Maternity Carer. Depending on the severity of the cardiac lesion, discussion and careful planning for the delivery and post partum care requires excellent communication between the mother, Lead Maternity Carer, anaesthetist and cardiologist.

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