Systolic anterior motion causing hemodynamic instability and pulmonary edema during bleeding

Area of Science:

• Cardiology
• Critical Care Medicine
• Echocardiography

Background:

• Systolic anterior motion (SAM) of the mitral valve is a condition where a mitral leaflet prolapses into the left ventricle outflow tract (LVOT) during systole.
• This can lead to LVOT obstruction and mitral regurgitation, causing hemodynamic instability.
• SAM has been described in various clinical settings, often associated with hypovolemia and sympathetic stimulation.

Observation:

• A 77-year-old woman with polycystic renal disease presented with abdominal bleeding and was initially normotensive despite anuria and acidosis.
• Following fluid and blood resuscitation, she developed atrial fibrillation, pulmonary edema, and severe hypotension after non-invasive ventilation.
• Transesophageal echocardiography revealed an "empty" hypertrophic, hypercontractile left ventricle with significant SAM, LVOT obstruction (154 mmHg gradient), and moderate-to-severe mitral regurgitation.

Findings:

• The patient's presentation mimicked fluid overload but was actually due to SAM-associated mitral regurgitation, diastolic dysfunction, and tachycardia leading to pulmonary edema in a hypovolemic state.
• Treatment with sedation and non-invasive ventilation exacerbated hypovolemia, precipitating LVOT obstruction and hypotension.
• Hemodynamic stability and sinus rhythm were restored with further fluid infusion, resolving SAM, LVOT obstruction, and mitral regurgitation.

Implications:

• Systolic anterior motion (SAM) is a critical, albeit rare, cause of hemodynamic instability that can be misdiagnosed.
• Echocardiography is essential for the accurate diagnosis and management of SAM-induced complications.
• Recognizing SAM's potential to mimic other conditions, like pulmonary edema, is crucial for appropriate treatment, especially in hypovolemic patients.