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 loud S1 and 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 fatigue, dyspnea, and tachycardia due to decreased oxygen-carrying capacity and increased cardiac output demands during pregnancy.
- Do Not Miss
- 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. It's a life-threatening condition that requires immediate diagnosis and treatment.
- Pulmonary hypertension: This condition can cause dyspnea, fatigue, and a loud S2 component, which might be mistaken for the sharp sound after S2 described in the scenario. It's crucial to consider, especially if there's any suspicion of elevated pulmonary pressures.
- Rare diagnoses
- Congenital heart defects: Certain congenital heart defects might not be diagnosed until adulthood, especially if they are mild or asymptomatic until increased cardiac demands during pregnancy unmask them. Examples include atrial septal defects or small ventricular septal defects.
- Cardiomyopathy: Peripartum cardiomyopathy is a rare but potentially life-threatening condition that occurs during the last month of pregnancy or within 5 months after delivery, in the absence of any other identifiable cause of cardiomyopathy. It could present with symptoms of heart failure, including dyspnea and fatigue.