In general, regurgitant lesions are well tolerated during pregnancy, whereas left sided stenotic lesions are not (increased circulating volume and cardiac output lead to a rise in left atrial pressure). Tissue valves can deteriorate rapidly during pregnancy. Management of patients with significant mitral and aortic stenosis
- Bedrest:
- Reduced heart rate allows time for LV filling and ejection
- Reduced venous return due to IVC compression by the uterus reduces LA pressure (also increases risk of thrombosis: patients must be heparinised).
- Dyspnoea and angina: slow the heart rate with beta blockers or digoxin. Nitrates may be useful, but should be used with caution in those with aortic stenosis.
- Intractable pulmonary oedema:
- Balloon valvotomy
- Closed mitral valvotomy (advantage as no cardiopulmonary bypass, but few surgeons nowadays have experience)
- If valvotomy not possible, then deliver fetus by Caesarean section followed by cardiopulmonary bypass and valve replacement.
Mechanical valves
Anticoagulation is the issue here: in particular, the risk of warfarin embryopathy vs risk of valve thrombosis.
The choice lies between:
- Warfarin throughout pregnancy, stopping it for a minimal length of time for delivery
- Convert to heparin during the first trimester with hospital admission and meticulous control of APTT. Return to warfarin for the second trimester and reinstate heparin at ~34/40.
- Mitral tilting disc prostheses at particular risk: fatal thrombotic occlusion of these valves in pregnant women described despite well-controlled heparin anticoagulation
- Risk of significant warfarin embryopathy not as high as previously thought, especially if the mother achieves adequate anticoagulation on <5mg>
- No data on low molecular weight heparin in this situation, so its use cannot be recommended.
The patient must be fully informed, and involved in deciding her mode of anticoagulation (medicolegal implications).
No comments:
Post a Comment