Physiological hemodynamic changes
During pregnancy, a woman's cardiovascular system works under immense strain. This is due to the formation of the new placental circulation system and a series of adaptive shifts:
- Circulating blood volume increases by 40–60%.
- Cardiac output increases by 40–50%.
- Total peripheral vascular resistance decreases.
It is precisely these physiological changes that cause many latent cardiovascular pathologies to first manifest clinically during pregnancy. The increased workload can transition a compensated disease into a stage of severe hemodynamic disorders.
Congenital and acquired heart defects
Heart defects are diagnosed in 4–9% of pregnant women. The most common pathology is mitral valve prolapse (MVP). Interestingly, the physiological enlargement of the left ventricular cavity and the decrease in vascular resistance during pregnancy can contribute to a reduction in the degree of prolapse. In the absence of significant regurgitation, pregnancy proceeds favorably.
However, other defects pose a serious threat and require strict monitoring:
- Septal defects (ASD, VSD) and patent ductus arteriosus: large defects cause left-to-right shunting, ventricular hypertrophy, and pulmonary hypertension. When irreversible pulmonary hypertension develops, pregnancy is contraindicated.
- Coarctation of the aorta: narrowing of the aortic isthmus leads to a sharp increase in systolic blood pressure and left ventricular hypertrophy, while blood flow in the lower half of the body suffers. This threatens fetal growth restriction (FGR) and aortic dissection.
- Tetralogy of Fallot: patients after incomplete surgical correction have a high risk of worsening heart failure. Right-to-left shunting is extremely dangerous due to the risk of cerebral thromboembolism.
- Severe aortic stenosis: decreased vascular resistance against the background of fixed cardiac output leads to myocardial ischemia. Maternal mortality reaches 15%, and pregnancy termination is indicated.
- Eisenmenger syndrome: the reversal of the shunt to right-to-left results in deoxygenated blood entering the systemic circulation. Maternal mortality reaches 50%. Pregnancy is absolutely contraindicated.
Among acquired defects, rheumatic lesions lead the way, especially mitral stenosis. The increase in heart rate and blood volume during pregnancy sharply raises the workload on the left atrium, threatening atrial fibrillation, pulmonary edema, and thromboembolism. With pronounced stenosis (orifice area ≤ 1.5 cm²), carrying the pregnancy is prohibited.
Essential Hypertension
Chronic arterial hypertension occurs in 4–5% of pregnant women. The diagnosis is confirmed if high blood pressure was present before conception or first recorded in the 1st trimester (normally, blood pressure should drop slightly in early stages).
Severe forms (BP from 200/115 mm Hg) and target organ damage are contraindications to pregnancy.
Specific complications:
- Preeclampsia (develops in 10–40% of cases).
- Placental abruption (2–3 times more frequent).
- Placental insufficiency and FGR (risk increases to 30–40% when complicated by preeclampsia).
Pregnant women require scheduled hospitalizations: up to 12 weeks (decision on continuation), at 28–32 weeks (peak hemodynamic load), and at 37–38 weeks (preparation for delivery).
Delivery is preferred via the natural birth canal with epidural anesthesia and shortening of the second stage of labor. In the third stage, oxytocin is used to prevent hemorrhage. The use of methylergometrine is absolutely contraindicated due to its vasopressor effect. Cesarean section is performed in case of treatment failure, eclampsia, HELLP syndrome, or retinal detachment.
Operated heart and venous diseases
Conception planning is allowed no earlier than 1 year after successful cardiac surgery. Patients with biological valve prostheses generally tolerate pregnancy well. The presence of a mechanical valve is associated with a high risk of thrombosis, making strictly monitored anticoagulant therapy vital for such women.
In addition to heart pathologies, 20–40% of pregnant women face varicose veins. In 70–90% of cases, it manifests precisely during gestation. The main culprits are hormones: relaxin and progesterone, which exert a relaxing effect on the vascular wall, provoking venous stasis.
Briefly: answers to topical questions
Which antihypertensive drugs are approved for use during pregnancy?
During pregnancy, the following antihypertensive drugs are indicated in sources:
- Nifedipine.
- Labetalol.
- Methyldopa (alpha-methyldopa), the drug of choice during pregnancy.
- Hydralazine.
What is the management strategy for pregnant women with mechanical heart valve prostheses?
The management strategy for pregnant women with mechanical heart valve prostheses requires mandatory monitoring of the coagulation system and careful delivery.
- Anticoagulant therapy is strictly indicated due to the high risk of thrombosis. It is recommended to consider warfarin intake from after 12 weeks of pregnancy until the stage of delivery.
- Delivery is performed carefully, via the natural birth canal.
- Cesarean section is indicated upon the appearance of symptoms of heart failure or the presence of obstetric indications.
Which classes of the mWHO scale are used for risk assessment in cardiovascular diseases in pregnant women?
To assess maternal risks of cardiovascular complications, the modified WHO (mWHO) classification is used. Available materials mention only one category of this scale:
- Risk category IV — this includes pregnant women with pulmonary hypertension. When this class is assigned, pregnancy is absolutely contraindicated due to extremely high risks of maternal mortality (25–56%).
Which ECG changes are considered physiological normal during pregnancy?
The materials indicate physiological sinus tachycardia during pregnancy.
- Sinus tachycardia may occur during pregnancy as a physiological factor. Treatment consists of identifying and eliminating the underlying cause.
The rule of three "Ps" for hypertension complications in pregnant women: Preeclampsia, Placental insufficiency, Placental abruption.
Class and exam questions
Is it safe to give birth with mitral valve prolapse?
Yes, in the absence of significant regurgitation, pregnancy proceeds favorably. The physiological enlargement of the left ventricle during pregnancy may even reduce the degree of prolapse.
When is pregnancy strictly contraindicated in heart defects?
In Eisenmenger syndrome, severe aortic stenosis, pronounced mitral stenosis (orifice diameter ≤ 1.5 cm), and the development of irreversible pulmonary hypertension.
Why is methylergometrine contraindicated during labor in hypertension?
This drug has a pronounced vasopressor effect, which can trigger a dangerous spike in blood pressure. Oxytocin is used to prevent bleeding.
What else to study on this topic
- Pathogenesis and risks of aortic coarctation in pregnancy
- Features of managing patients with Tetralogy of Fallot after incomplete surgical correction
- Critical periods of rheumatic fever exacerbation in pregnant women
- Timing and goals of scheduled hospitalization in essential hypertension
- Mechanisms of varicose vein development against the background of rising progesterone and relaxin
Master the entire topic in the "Obstetrics and Gynecology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Cardiovascular diseases in pregnancy" and another 973 pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 21 video lessons on the subject
Other topics in the "Obstetrics" section
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.