From the Guidelines
Pregnancy can cause high output heart failure due to the significant cardiovascular changes that occur during gestation, including a 30-50% increase in blood volume and cardiac output, and a 10-20 beat per minute increase in heart rate, as noted in the most recent study 1.
Key Changes During Pregnancy
- Blood volume increases by 30-50%
- Cardiac output rises by 30-50%
- Heart rate increases by 10-20 beats per minute
- Systemic vascular resistance decreases These changes, coupled with the increased metabolic demands of pregnancy and the additional blood flow required by the placenta, place additional strain on the heart, potentially leading to cardiac overload.
Management and Monitoring
Management involves treating underlying conditions like anemia, controlling blood pressure, restricting salt intake, and sometimes using diuretics or beta-blockers as appropriate, as recommended in 1. Close monitoring of cardiac function throughout pregnancy is essential for women at risk, with multidisciplinary care involving obstetricians and cardiologists to ensure optimal outcomes for both mother and baby.
Risks and Considerations
The risk of pregnancy is considered greater than the risks linked to contraceptive use, and women with heart failure should discuss contraceptives and planned pregnancy with a physician to take an informed decision based on assessment of potential risks, as stated in 1. Additionally, the physiologic changes induced by pregnancy impose a marked hemodynamic stress in women with IPAH, leading to a previously estimated 30% to 50% mortality rate, as reported in 1.
From the Research
Physiological Changes in Pregnancy
Pregnancy is associated with significant physiological changes that can lead to high output heart failure. Some of the key changes include:
- Increased blood volume: Pregnancy leads to an increase in blood volume, which can put additional strain on the heart 2.
- Increased cardiac output: Cardiac output increases during pregnancy to meet the increased metabolic demands of the mother and fetus 2.
- Decreased systemic vascular resistance: Pregnancy is associated with a decrease in systemic vascular resistance, which can lead to a decrease in blood pressure 3, 2.
High Output Heart Failure in Pregnancy
High output heart failure is a condition where the heart is unable to meet the body's needs despite an increased cardiac output. In pregnancy, high output heart failure can occur due to:
- Increased metabolic demands: The increased metabolic demands of the mother and fetus can lead to an increase in cardiac output, which can put additional strain on the heart 2.
- Decreased systemic vascular resistance: The decrease in systemic vascular resistance during pregnancy can lead to a decrease in blood pressure, which can cause the heart to work harder and increase cardiac output 3, 2.
- Underlying medical conditions: Women with underlying medical conditions such as anemia, thyroid disease, or cardiomyopathy are at increased risk of developing high output heart failure during pregnancy 3, 4.
Clinical Implications
High output heart failure in pregnancy is associated with significant maternal and fetal morbidity and mortality. Women with high output heart failure during pregnancy are at increased risk of:
- Adverse maternal outcomes: High output heart failure is associated with an increased risk of adverse maternal outcomes, including maternal mortality and morbidity 5, 6, 4.
- Adverse fetal outcomes: High output heart failure is also associated with an increased risk of adverse fetal outcomes, including low birth weight and preterm birth 5, 6, 4.
- Increased risk of complications: Women with high output heart failure during pregnancy are at increased risk of complications, including cardiac arrhythmias, cardiac arrest, and respiratory failure 3, 4.