Acute right to left shunt through patent foramen ovale presenting as hypoxemia after myocardial infarction: a case report

The dilemma of refractory hypoxemia after inferior wall myocardial infarction

Patent foramen ovale (PFO) occurs in 25% of people. The decision on whether to close the PFO found after myocardial infarction and specifically right ventricular infarction is debated, with no solid guidelines addressing this subject. Here we present the case of a 59-year-old man who presented with a myocardial infarction and was found to have PFO. He was treated with revascularization of the culprit artery, followed by supportive care.

Persistent Hypoxemia After Acute Myocardial Infarction: An Unexpected Culprit

Hypoxemia after myocardial infarction (MI) is usually explained by common culprits, including congestive heart failure, pre-existing lung disease, and pulmonary infection. We report a case of a 60-year-old woman who experienced severe persistent hypoxemia caused by a patent foramen ovale in the setting of anterior MI complicated by a contained left ventricular rupture.

Not all unexplained hypoxia is pulmonary embolism

Acute myocardial infarction is one of the conditions frequently managed in the emergency department. There are many complications associated with right ventricular infarction, and the incidence of right ventricular infarction associated with inferior myocardial infarction is as high as 51% based on electrocardiographic findings. We herein report the case of a 45-year-old Chinese man with inferior myocardial infarction complicated by right ventricular failure. He had hypoxaemia refractory to supplemental oxygen due to an acute right-to-left shunting through a patent foramen ovale (PFO). He underwent coronary angioplasty and closure of the PFO. It is crucial for the attending physician to consider the presence of a right-to-left shunt when there is persistent uncorrectable hypoxaemia despite maximal oxygen supplementation in the setting of right ventricular infarction, as there are clinical implications and certain clinical managing principles that should be applied.

Transient right-to-left intracardiac shunt following a right ventricular myocardial infarction

A 56-year-old smoker presented with a 3-day history of intermittent chest pain. Cardiovascular examination on admission was normal. ECG showed minimal (<1 mm) ST elevation in lead III, and right-sided leads revealed similar mild ST-elevation. Troponin I was elevated at 10.91. He was managed as a delayed-presentation ST-elevation myocardial infarction case. 12 h following admission, he developed oxygen-resistant hypoxia and hypotension. There were no clinical or radiological signs of pulmonary congestion. CT pulmonary angiogram revealed no pulmonary embolus. A bubble-contrast echocardiogram confirmed an active interatrial right-to-left shunt without Valsalva provocation. His hypoxia steadily improved over the following 24 h and he did not require any shunt closure. A repeat bubble contrast echocardiogram showed that the shunt was now only active following a Valsalva manoeuvre. Transoesophageal echocardiography confirmed a patent foramen ovale. This is a rare but important cause of resistant hypoxia following a right-heart infarct.