How should severe aortic stenosis be managed in a woman who is 24 weeks pregnant?

Management of Severe Aortic Stenosis at 24 Weeks Gestation

A pregnant woman with severe aortic stenosis at 24 weeks gestation requires immediate multidisciplinary management at a tertiary care center with close monitoring, medical optimization to maintain hemodynamic stability, and consideration for percutaneous balloon aortic valvuloplasty only if she develops refractory heart failure symptoms despite maximal medical therapy. 1

Immediate Risk Assessment and Monitoring

Patients with severe aortic stenosis tolerate pregnancy poorly due to the inability to augment cardiac output in response to pregnancy's hemodynamic demands - specifically the 30-50% increase in cardiac output, increased heart rate, and decreased systemic vascular resistance. 1 This creates a critical mismatch between physiologic demands and cardiac capacity that can lead to rapid decompensation.

Essential Initial Evaluation

• Confirm severity with comprehensive transthoracic echocardiography to assess valve area, gradients, left ventricular function, and pulmonary pressures 1
• Assess aortic root dimensions carefully, as bicuspid aortic valve (the most common etiology in young women) is associated with aortopathy and risk of aortic dilation/dissection during pregnancy 1
• Evaluate functional capacity and symptoms including dyspnea, angina, syncope, or signs of heart failure 1
• Transfer immediately to a tertiary center with a dedicated Heart Valve Team including maternal-fetal medicine, cardiology, cardiac surgery, and cardiac anesthesiology 1

Medical Management Strategy

The cornerstone of management is maintaining hemodynamic stability through careful medical optimization while avoiding interventions that could destabilize the patient. 1, 2

Critical Hemodynamic Principles

• Maintain adequate preload - these patients are preload-dependent and require sufficient venous return to maintain cardiac output across the stenotic valve 3
• Avoid excessive diuresis that could reduce preload and precipitate hypotension 3
• Control heart rate meticulously to preserve diastolic filling time and coronary perfusion; tachycardia is particularly dangerous 3
• Avoid vasodilators that can cause catastrophic hypotension in fixed cardiac output states 3
• Strict activity restriction and bed rest if symptomatic to minimize cardiac demands 1, 2

Monitoring Frequency

• Monthly or bimonthly clinical and echocardiographic evaluations to assess for clinical deterioration, changes in valve hemodynamics, or development of left ventricular dysfunction 1
• Continuous fetal monitoring for signs of uteroplacental insufficiency 4, 2

Intervention Thresholds

Percutaneous balloon aortic valvuloplasty should be considered only as a life-saving measure in patients with severe, refractory heart failure symptoms despite maximal medical therapy. 1, 5

Indications for Balloon Valvuloplasty

• Severe symptomatic aortic stenosis with signs of heart failure unresponsive to medical management 1, 5
• Pulmonary congestion that cannot be controlled medically 5
• Hemodynamic instability threatening maternal or fetal survival 1, 5

Important Caveats About Intervention

• Balloon valvuloplasty during pregnancy is high-risk and should only be performed in highly experienced centers with expertise in both structural interventions and high-risk obstetrics 1, 5
• Minimize radiation exposure through abdominal shielding, avoiding hemodynamic measurements when possible, and limiting fluoroscopy time 1
• Continuous fetal heart rate monitoring should be performed during the procedure 4, 5
• The procedure provides only palliative benefit and does not eliminate the need for definitive valve replacement postpartum 1, 5

When Surgical Valve Replacement Is Necessary

Open cardiac surgery with cardiopulmonary bypass carries substantial fetal risk (fetal mortality 20-30%) but may rarely be necessary for maternal survival in cases of refractory heart failure. 4 If required, this should be performed in the second trimester when possible, with continuous fetal monitoring and maintaining high pump flows and perfusion pressures. 4

Delivery Planning

Vaginal delivery with epidural anesthesia is generally preferred if the patient remains stable, with cesarean section reserved for obstetric indications. 1, 2

Delivery Considerations

• Plan delivery at 36-38 weeks in a tertiary center with cardiac surgery backup immediately available 1, 2
• Epidural anesthesia is preferred to minimize hemodynamic fluctuations and provide pain control that prevents tachycardia 1, 2
• Avoid general anesthesia if possible due to risks of hemodynamic instability 1
• Assisted second stage (forceps or vacuum) to minimize maternal Valsalva and cardiac work 2
• Invasive hemodynamic monitoring (arterial line, consider pulmonary artery catheter) during labor and delivery 1, 2

Critical Pitfalls to Avoid

• Never assume the patient will remain stable - severe aortic stenosis can decompensate rapidly during pregnancy, particularly in the third trimester when hemodynamic demands peak 1
• Do not delay transfer to a tertiary center - these patients require specialized expertise that is not available at community hospitals 1
• Avoid tachycardia at all costs - even modest increases in heart rate can precipitate hemodynamic collapse by reducing diastolic filling time and coronary perfusion 3
• Do not use prophylactic balloon valvuloplasty in asymptomatic or mildly symptomatic patients - the risks outweigh benefits 1

Postpartum Management

Definitive aortic valve replacement should be planned for 3-6 months postpartum once the patient has recovered from delivery and completed breastfeeding if desired. 1 The choice between mechanical and bioprosthetic valves should be discussed, weighing the need for lifelong anticoagulation with mechanical valves against the limited durability of bioprosthetic valves in young patients. 1