Differential Diagnosis
- Single most likely diagnosis
- Mitral stenosis: The presence of a low-frequency diastolic murmur at the apex that increases in intensity before S1, along with a sharp sound after S2 (likely an opening snap), is highly suggestive of mitral stenosis. The symptoms of excessive fatigability and dyspnea, especially during pregnancy when cardiac output increases, further support this diagnosis.
- Other Likely diagnoses
- Pulmonary embolism: Although the lungs are clear to auscultation, the symptoms of dyspnea and tachycardia (pulse is 110/min) could also suggest a pulmonary embolism, particularly in a pregnant woman who is at increased risk for thromboembolic events.
- Anemia of pregnancy: This condition can cause symptoms of excessive fatigability and dyspnea due to decreased oxygen-carrying capacity, but it would not explain the specific cardiac findings.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cardiac tamponade: Although less likely given the absence of specific findings like pulsus paradoxus or a significant decrease in blood pressure, cardiac tamponade can present with tachycardia and dyspnea. The non-palpable cardiac apex could be a clue, but this is more likely due to the patient's body habitus or pregnancy-related changes.
- Pulmonary hypertension: This condition can cause dyspnea and tachycardia, and the sharp sound after S2 could be misinterpreted. However, the presence of a diastolic murmur at the apex is not typical for pulmonary hypertension.
- Rare diagnoses
- Congenital heart defects: Certain defects, like atrial septal defects or ventricular septal defects, can present with dyspnea and tachycardia, especially during pregnancy. However, these would typically be diagnosed earlier in life, and the specific murmur described is not characteristic of these defects.
- Cardiomyopathy: Peripartum cardiomyopathy is a rare condition that occurs during the last month of pregnancy or within 5 months after delivery, characterized by left ventricular dysfunction. While it could explain the symptoms, the specific cardiac findings described do not directly point to cardiomyopathy.