You are called to the labour ward because a 34-year-old woman has become breathless and orthopnoeic 2 hours after delivery. She is pain free. On examination she is tachycardic, tachypnoeic, and has a gallop rhythm. Blood pressure is 136/86 mmHg. On auscultation of her chest she has fine inspiratory crackles to the mid-zones.
What is the most likely diagnosis?
A. Pulmonary embolismThis is a typical picture of peripartum cardiomyopathy (often undiagnosed dilated cardiomyopathy, which decompensates at this time of extreme increase in preload). The largest haemodynamic changes in pregnancy occur in the post-partum period. During labour and delivery, pain and uterine contractions result in additional increases in cardiac output and blood pressure. Immediately after delivery, relief of caval compression and autotransfusion from the emptied and contracted uterus produce a further increase in cardiac output (50–70% more than baseline overall). Most haemodynamic changes of pregnancy resolve by 2 weeks post-partum. Myocardial infarction in pregnancy is generally accompanied by pain, and pulmonary embolus does not result in signs of left heart failure. Tachyarrhythmia in pregnancy is common and is not usually associated with ventricular decompensation. Amniotic fluid embolus is rare and presents with shortness of breath leading to hypotension, cyanosis, and cardiac arrest.