Which cardiac condition is a modified World Health Organization (WHO) Risk Class IV lesion for which pregnancy is extremely dangerous and not recommended: Repaired Ventricular Septal Defect (VSD), Pulmonary Artery Hypertension (PAH), Supraventricular Arrhythmias, or Hypertrophic Cardiomyopathy?

WHO Risk Class IV Cardiac Lesion in Pregnancy

The correct answer is (b) Pulmonary artery hypertension, which is classified as WHO Risk Class IV and represents an absolute contraindication to pregnancy with maternal mortality rates of 30-50%. 1

Classification of Each Cardiac Condition

Pulmonary Arterial Hypertension (PAH) - WHO Class IV

• PAH is the only condition among the options that is classified as WHO Risk Class IV, representing extremely high risk of maternal mortality or severe morbidity where pregnancy is absolutely contraindicated. 1
• The European Society of Cardiology guidelines explicitly state that women with PAH should be advised against pregnancy regardless of symptom severity. 1
• Maternal mortality ranges from 30-50% in PAH during pregnancy, making it the highest risk cardiac condition in pregnancy. 1
• The modified WHO classification confirms PAH falls into mWHO class IV with estimated maternal cardiac event rates ranging from 40-100% during pregnancy. 2

Repaired VSD - WHO Class I

• Successfully repaired ventricular septal defects are classified as WHO Risk Class I, representing no detectable increased risk of maternal mortality and no/mild increase in morbidity. 1
• This is the lowest risk category and pregnancy is not contraindicated. 1

Supraventricular Arrhythmias - WHO Class II

• Most arrhythmias, including supraventricular arrhythmias, are classified as WHO Risk Class II, representing only small increased risk of maternal mortality or moderate increase in morbidity. 1
• These conditions require monitoring but pregnancy is not contraindicated. 1

Hypertrophic Cardiomyopathy - WHO Class II-III

• Hypertrophic cardiomyopathy is classified as WHO Risk Class II-III, representing significantly increased risk requiring expert counseling. 1
• Pregnancy is not absolutely contraindicated as it is in Class IV conditions. 1

Why PAH is Uniquely Dangerous

Pathophysiologic Mechanisms

• Life-threatening rises in pulmonary vascular resistance develop particularly rapidly in the peripartum and postpartum periods due to pulmonary thrombosis or fibrinoid necrosis. 1
• Right ventricular overload increases with systemic vasodilation, worsening right-to-left shunting and cyanosis. 1
• The condition can prove fatal even in patients who previously had minimal disability. 1

Critical Time Periods

• Maternal death from pulmonary hypertensive crises or refractory right heart failure occurs predominantly in the last trimester and first months postpartum. 3
• The first 48-72 hours post-delivery represent the highest risk window. 3