HEART DISEASE AND PREGNANCY

Pregnancy is a natural hazard to the young female cardiac patient, and the frequency of the problems to which the association of the two conditions gives rise may be gauged from the fact that between 1-5 and 3 per cent. of all women attending ante-natal clinics are found to have cardiac lesions. The great majority (90 per cent.) of these are cases of rheumatic valvular disease; a much smaller proportion have congenital malformations; ischasmic heart disease in the pregnant woman is rare.
Pregnancy imposes a severe strain on the cardiovascular system of handi¬capped patients and in a considerable proportion the heart cannot withstand the additional burden so that cardiac failure in one form or another ensues. The increased load on the circulation is in part imposed by the metabolic demands of the pregnant state, but there are also hasmodynamic factors of considerable importance. The large placental circulation acts as an arterio-venous shunt, imposing a considerable burden on the heart. Further, during pregnancy the blood volume increases progressively in the early months to reach a peak at or about the 32nd week and thereafter slowly falls towards normal. The load imposed by this increased circulating volume is thus at its maximum, which explains why disability is usually maximal at that time and that thereafter symptoms may regress.
The diagnosis of heart disease in a woman seen for the first time during pregnancy can be difficult. Every cardiologist can recall patients in whom murmurs heard during pregnancy suggest a valvular lesion and yet on re-examination after delivery no murmurs are heard and there is no clinical evidence of heart disease. It is probable that the increased cardiac output associated with the high blood volume during pregnancy is responsible for these transient murmurs.
The best guide as to how a woman with a cardiac lesion will withstand pregnancy is afforded by her previous history. The first question is to determine how far she was handicapped before the pregnancy began. The woman who previously had little or no disability is unlikely to come to serious harm during its course, and conversely the woman who before pregnancy was already seriously handicapped or in failure will certainly be in danger so long as the pregnancy continues, and in fact well into the puerperium. Other factors to be considered are first the age of the patient, as the risks increase steeply with advancing age ; secondly, the parity, since successive labours are likely to be shorter and to impose less burden on the heart; thirdly, the previous obstetric history in so far as the cardiac complications of pregnancy were concerned ;
fourthly, her circumstances, such as wage-earning and domestic duties which may or may not permit her to rest adequately; fifthly, the co-existence of other complicating disorders such as anaemia and renal disease; and sixthly, obstetric factors (disproportion, etc.).
One class of case constitutes a striking exception to these general rules— the patient with a tight mitral stenosis, probably with a small heart and normal cardiac rhythm, who develops episodes of acute paroxysmal dyspnoea due to pulmonary congestion secondary to left atrial failure. Although such patients may have in the intervals little breathlessness or other handicap, they are in peril, and it is among these individuals that a great proportion of the fatal cases arise. In such patients mitral valvulotomy during pregnancy may save life.
Probably the most important single factor in the safe management of the pregnant cardiac patient is regular careful ante-natal supervision. In most hospitals there is a close liaison between the obstetric unit and the cardiologist. Thus the early signs of incapacity or failure can be detected and dealt with, decisions as to interruption of pregnancy can be taken jointly, and during the final obstetric management of the case the advice of the physician will be available to deal with heart failure or any other emergency which may arise either at term or in the puerperium. With such care the maternal mortality can be reduced to a very low figure in comparison with the high mortality among women who continue their pregnancy unsupervised and who seek medical advice only when driven to do so because of serious incapacity. Although patients seek help at all stages of pregnancy it is convenient to consider the management of those seen for the first time during each of the three trimesters. Some broad guiding principles, however, may first be considered.
The general rules as to obstetric management are relatively simple. In the first place, interruption of the pregnancy, if this is deemed necessary, should not be carried out later than the third month ; thereafter the risks of interference are greater than the risks of allowing the pregnancy to proceed, so that a patient seen for the first time in the fourth month or later even if she is in failure should on no account be subjected to therapeutic abortion. Again, when as the result of good management, a patient has successfully reached the last few weeks of pregnancy, a decision has sometimes to be taken regarding the manner of delivery, whether per vaginam or by Csesarean section. The consensus today is against Cassarean section, which formerly was carried out about the 37th week as an operation of election to spare the mother the strain of labour. The risks involved, however, are greater than if the woman is allowed to go to term, and the infant mortality is considerably higher. Provided there are no obstetrical complications, a forceps delivery can usually be achieved without difficulty, and fortunately many of the infants born to these women are small. It should be emphasized that the more serious the patient's cardiac condition appears to be on admission to the obstetric unit, the more important it is not to interfere with the pregnancy until the cardiac failure has been controlled; only then should obstetrical interference be considered. This rule applies at all stages of preg¬nancy. As stated above, interruption of pregnancy after the third month is unwise. A decision to perform sterilization should not be used as an argument in favour of Csesarean section; this can be carried out at a later date when the hazards of pregnancy have been surmounted. It should be remembered that the risks are not over when the woman has been delivered of her child; cardiac failure may supervene in the puerperium and may prove fatal.
First Trimester.—During the first trimester important decisions must be taken regarding the management of the individual patient. In these the prac¬titioner is guided by the factors enumerated above, forecasting the likelihood of a stormy or peaceful pregnancy from the previous history. Where there has been no previous disability a patient seen in this period should be reassured and supervised at regular intervals ; as the pregnancy advances she should be encouraged to rest more than the average pregnant woman, particularly in the later months. When there has been some previous handicap or the history of some cardiac complication in a previous pregnancy, the risks of continuing the pregnancy should be explained to the patient and her husband and the advis¬ability of therapeutic abortion considered. When the patient has been seriously incapacitated or has developed cardiac failure, or when serious failure has complicated previous confinements, termination of pregnancy should be strongly advised. If the patient is already in failure when seen, as emphasized above, no interference with the pregnancy should be permitted until the failure has been relieved. Thereafter its termination is advisable.
Second Trimester.—From the fourth month onwards interference with the course of the pregnancy is contraindicated, and the management of the patient consists of the assessment of the degree of handicap and of the treatment of cardiac failure if this is present. Even in patients with little disability it is wise to insist on additional rest in the afternoons and at week-ends and in those more seriously affected complete rest in bed may have to be imposed even at this early date. Appropriate treatment with diuretics, salt restriction and digitalis will assist the patient through the remaining months of her pregnancy.
Third Trimester.—Patients who pass through the first six months of pregnancy without ill effect and who develop signs of failure in the third trimester will require admission to hospital and treatment, but in general they may be expected to improve in the last weeks of the pregnancy and may be less upset by labour than might be anticipated. It should be reiterated that no matter how severe the failure or how desperate the handicap surgical obstetrical interference at this stage is contraindicated.
Puerperium.—Cardiac failure after delivery is a very serious matter : the spontaneous amelioration which occurs with the reduction of the blood volume in the later weeks of pregnancy cannot be expected, since the blood volume has already returned to normal. The death rate among patients in failure at this stage is high and the failure is often refractory to standard treatment. When for one reason or another breast-feeding is undesirable, it should be remembered that cestrogens given to suppress lactation favour water and sodium retention.
Advice on Child-bearing.—Young married women and their husbands frequently ask advice on this matter, and the doctor must be prepared to guide them to the best of his ability. It is a great mistake to defer pregnancy in a young patient who is married and desires a child. If she is fit to have a child she should be encouraged to have one, since with each year that passes she will become older and less able to withstand the strains involved. Pregnancy carries no undue risk for the woman who is little handicapped by her lesion, though for the woman whose capacity for effort is already restricted pregnancy is a grave hazard. A thoughtless ban imposed by a doctor playing for safety may be productive of much distress and unhappiness, and it is unfortunate that such prohibitions are widely enforced without due consideration. When the patient's handicap is definite though not gross, and when the practitioner anticipates that —at least in the later weeks of pregnancy—the patient is likely to be in failure and confined to bed, the position should be explained to the prospective mother. Many women are more than willing to accept such a risk in their desire to have a child, but in such patients repeated pregnancies should be discouraged. One baby may be safely achieved; a second child after a year or two may be feasible and on family grounds is highly desirable to avoid the disadvantage of the only child.
It is commonly forgotten that the burden imposed by child-bearing does not cease with delivery. Caring for the child during infancy and early childhood may impose on the mother a greater strain than the pregnancy. Where there are two or three children in the family under the age of five the physical load on the mother with cardiac disease may be formidable.