Pharmacology of Obstetrics
Pregnancy is a physiological stress test for the heart. Cardiac disease in a pregnant woman can dramatically increase maternal and fetal risk, making early recognition and multidisciplinary management essential.
Physiological Changes
- Blood volume ↑30–50%
- CO ↑30–50%
- SVR ↓
- Hypercoagulable
Common Causes
- Congenital: ASD, VSD
- Rheumatic: Most common LMICs
- Cardiomyopathies
- Ischemic, arrhythmias
Maternal Risks
| Lesion | Risk |
|---|---|
| Obstructive | Pulmonary edema, AF |
| Regurgitant | Tolerated unless LV dysfunction |
| PHTN | High mortality |
| Cardiomyopathy | HF |
| Arrhythmias | HF, compromise |
NYHA III–IV = contraindication
Fetal Risks
- Preterm birth
- IUGR
- Stillbirth
- CHD
Cyanosis <85% = high fetal risk
Antenatal Management
Preconception
- Assess class, function
- Avoid teratogens (ACEi, warfarin)
Antenatal
- Multidisciplinary
- Beta-blockers, diuretics
- Activity modification
Symptoms worsen 28–32w
Intrapartum & Postpartum
- Vaginal preferred
- Epidural, fluid management
- Postpartum: high risk 72h
- Anticoagulation if needed
Key Takeaways
- Changes ↑preload, ↓afterload
- High maternal mortality in PHTN
- Cyanosis → fetal risks
- Multidisciplinary care
- Vaginal delivery
- Critical postpartum 72h
Conclusion
Cardiac disease requires teamwork. Early counseling and monitoring save lives.
Cardiac disease in pregnancy is a stress test — prepare well.