Pregnancy results in stress on the cardiovascular system.
During the first 24 weeks of pregnancy, the plasma volume increases by about 40%. This causes the heart to increase the cardiac output gradually by about 50%, primarily by an increase in the stroke volume. Add to this the increase in heart rate by about 10 to 15 beats per minute during the last three months of pregnancy.
There is tremendous stress on the mother during labor. The cardiac output increases by about 50% during active labor, and approximately 80% immediately after delivery.
While women with normal hearts adapt themselves to the stress, those with weak hearts are often unable to do so. Women with a reduced ejection fraction run the risk of becoming acutely breathless, and their blood may have sub-optimal oxygen.
Of course, they should visit the doctor before they become pregnant.
It is the doctor’s duty to explain the risks to the mother and the fetus. Medicines such as angiotensin converting enzyme inhibitors, angiotensin receptor blockers, and endothelin receptor blockers that result in fetal damage should be stopped before the woman becomes pregnant.
Certain forms of heart disease are genetically inherited. The prospective parents should be questioned about the prevalence of congenital heart disease among close relatives.
The couple should be counselled to do the ante-natal check-up and confinement in centers where specialized medical care is available.
Unfortunately, couples visit a specialist doctor for the first time when the pregnancy is advanced.
Pulmonary artery hypertension, congenital cyanotic heart disease, severe aortic stenosis with symptoms, severe mitral stenosis, left ventricular systolic dysfunction with ejection fraction < 30% or symptoms > NYHA class II, hugely dilated aorta in Marfan’s syndrome, and aorta > 5 cm diameter in women with bicuspid aortic valve.
This is done with the help of the WHO score. This has Class I (low risk), Class II (moderate risk), Class II to III (moderate to high risk), Class III (high risk), and Class IV (extremely high risk, pregnancy contra-indicated).
You have asked me a controversial question. There is a difference between what the Americans and Europeans do.
The American Congress of Obstetricians and Gynecologists recommends that we start giving medicines when the blood pressure exceed 160/105 mmHg.
The European Society of Cardiology recommends treatment when the blood pressure exceeds 140/90 mmHg.
Intravenous medicines: labetalol, hydralazine.
Oral medicines: labetalol, methyldopa, long-acting nifedipine.
This article is for the general information of the members of the public regarding heart disease, and is not intended to be a substitute for expert medical advice. Therefore, for all matters related to the diagnosis and management, please consult your health care giver.