Cardiovascular Disease in Pregnancy Part II: Classifications and Valvular Disease
/There are multiple systems for the classification of cardiac disease in pregnancy:
Modified WHO Pregnancy Risk Classification - this scale is based on the presumptive risk of cardiac disease towards pregnancy outcomes.
Class I: no detectable increase in maternal mortality, and no or only mild increase in morbidity.
Ex: uncomplicated/small/mild pulmonary stenosis, PDA, mitral valve prolapse; successfully repaired simple lesions (PDA or septal defects); isolated atrial or ventricular ectopic beats
Class II: small increased risk in maternal mortality, moderate increase in morbidity.
Ex: unoperated ASD or VSD; repaired tetralogy of Fallot; most arrhythmias.
Class III: significantly increased risk of maternal mortality or severe morbidity. Recommended intensive specialist cardiac and obstetric monitoring throughout pregnancy, delivery, and postpartum.
Ex: mechanical valve, systemic right ventricle, Fontan circulation, unrepaired cyanotic heart disease, aortic root dilation 40-45mm in Marfan patient or 45-50mm in bicuspid valvular disease.
Some patients may fall into an in between II-III category (i.e.,m mild LV impairment, HCM, Marfan syndrome without root dilation).
Class IV: extremely high risk of maternal mortality or severe morbidity; pregnancy considered contraindicated with recommendation for termination if pregnancy occurs. If continues, manage with specialist involvement as per class III.
Ex: pulmonary arterial hypertension, severe systemic ventricular dysfunction (LVEF < 30%), previous peripartum cardiomyopathy with any residual LV dysfunction, severe mitral or aortic stenosis; aortic root dilation in Marfan syndrome > 45mm or >50mm in bicuspid disease; native severe aortic coarctation.
NYHA Functional Classification - likely a familiar scale, based off of cardiac disease symptoms and functional status.
Class I - cardiac disease, but no symptoms and no limitations in ordinary physical activity
Class II - mild symptoms and slight limitations during ordinary activity
Class III - significant limitation in activity due to symptoms. Comfortable at rest
Class IV - severe limitations. Symptoms even while at rest.
CARPREG II or ZAHARA - point-based scales for risk prediction for a significant cardiac event in pregnancy:
Valvular Disease
Native Valvular Disease
Stenosis - the valve is narrowed or stiffened and does not allow for passage of blood.
Tricuspid stenosis - makes it hard for blood to pass from the right atrium into the right ventricle.
With increased cardiac output as well as increased systemic volume, stenosis of the tricuspid valve can lead to systemic overload (ie. swelling, JVD, etc); severe stenosis can make it so that less blood gets into the pulmonary system.
Pulmonic stenosis - blood is impaired in passage from RV to lungs.
In isolation, this is generally well tolerated since pregnancy provides additional volume, thus providing more blood to pump to the lungs in totality.
However, can be associated with other complex heart disease, in which outcomes are not as good.
Mitral stenosis - blood flow challenged from LA to LV.
Most common cause worldwide: rheumatic heart disease.
Increased CO and HR leads to decreased filling (diastolic) time. This promotes increased left atrial pressure and dilation, leading to atrial fibrillation, pulmonary edema.
Maternal mortality with severe MS is 3%.
Treatment in pregnancy is with beta blockers to decrease HR and increase filling time. Anticoagulation needed if atrial fibrillation develops.
Aortic stenosis - blood flow impaired from LV to aorta.
Most common cause: bicuspid aorta (congenital).
Pregnancy well tolerated except for patients with severe disease; need good flow systemically to accommodate increased cardiac output and stroke volume demand of pregnancy.
Severe AS can result in heart failure, arrhythmias, and pulmonary edema.
Regurgitation - insufficiency across a valve, allowing for backflow of blood.
Tricuspid regurgitation: overall well-tolerated, but higher risk of right-sided failure and atrial arrhythmia.
Pulmonic regurgitation: moderate or severe cases may lead to RV failure and arrhythmia.
Mitral regurgitation: usually well tolerated as long as there is absence of LV systolic dysfunction or pulmonary hypertension.
If severe, ideally valve is repaired or replaced prior to pregnancy.
Aortic regurgitation: also well-tolerated overall, unless signifiant baseline symptoms.
Risk of heart failure due to volume overload; can also occur alongside LV systolic dysfunction, severe LV dilation, or pulmonary hypertension.
Mechanical or Prosthetic Valves
There is an increased risk of thrombosis/VTE in pregnancy, and these patients will need to be on anticoagulation.
Warfarin is the preferred anticoagulant despite risk of embryopathy, as the risk of thrombus is higher on heparin or heparin-like agents.
Pearls on managing valvular disease in various stages of pregnancy:
Prepregnancy
Depending on severity, may need have preconception counseling with cardiologist and MFM.
Patients with severe mitral and aortic stenosis may need balloon valvuloplasty beforehand.
During pregnancy
Really, this is based on their cardiovascular risk score (ie. WHO classification)
Most of these patients will need an echocardiogram during early pregnancy, and likely follow up at an interval depending on hemodynamic tolerance.
Evaluate and treat any symptoms of heart failure!
Labor and delivery: vaginal delivery is usually the preferred method of delivery unless:
Mitral stenosis with NYHA class III/IV or have pulmonary hypertension
Severe, symptomatic AS
Especially with more severe symptoms, consider early epidural (especially in mitral stenosis) and assisted second stage.
Telemetry if risk for arrythmia exists.
After delivery
For many of these lesions, need to reevaluate an echocardiogram.
Many of these patients, due to fluid shifts, are at higher risk for arrhythmias and heart failure after delivery.
Strict I/Os in the postpartum period!
Consider telemetry if risk for arrhythmia.