Introduction

A 22-year-old woman with a large unrepaired ventricular septal defect presented with significant haemoptysis. She was 22 weeks pregnant at the time. Her resting oxygen saturation was 78%, and her haematocrit was 66%. How should this complicated patient be managed? Should one recommend acute endotracheal intubation, phlebotomy or termination of her pregnancy? How should providers navigate the complicated decision-making needed in her critical situation?

Adults with cyanotic congenital heart disease represent a wide variety of defects and histories. Some are those for whom corrective surgery either was not or could not be offered who, in spite of this, beat the odds and survived. Despite anecdotes of being told they would not live to reach the age of 4, 12 or 21, some have survived to their 60th decade or beyond. Others are those who had various palliative surgeries but did not achieve complete separation of pulmonary and systemic blood flow. For most, exertional tolerance is below normal, but they otherwise carry on with life, careers and family. Many are relatively stable, with often fewer hospital encounters, for example, than some of their palliated counterparts. They participate in activities that defy many providers’ expectations, such as maintaining full-time employment, air travel,1 living at high altitude2 or neurosurgery. They have developed important physiological adaptations that allow them to carry on, although with an ongoing risk that their fragile balance could be unfavourably tipped at any time.

These patients rely on life-sustaining haematological adaptations to their chronic cyanosis, and are at risk of adverse consequences if such adaptations are out of balance. Clinical events may reflect either inadequate …