Differential Diagnosis for Syncope
The differential diagnosis for syncope is broad and can be categorized based on the likelihood and potential impact of missing a diagnosis.
Single Most Likely Diagnosis
- Vasovagal Syncope: This is the most common cause of syncope, especially in young individuals. It is often triggered by stress, pain, or prolonged standing, leading to a sudden drop in blood pressure and heart rate, resulting in a brief loss of consciousness.
Other Likely Diagnoses
- Orthostatic Hypotension: A drop in blood pressure upon standing, which can be due to dehydration, medication side effects, or autonomic nervous system dysfunction.
- Cardiac Arrhythmias: Conditions like supraventricular tachycardia (SVT) or ventricular tachycardia can lead to syncope by disrupting the normal heart rhythm.
- Hypertrophic Cardiomyopathy: A condition where the heart muscle becomes thickened, which can obstruct blood flow and lead to syncope, especially during exertion.
Do Not Miss Diagnoses
- Pulmonary Embolism: Although less common, a pulmonary embolism can cause syncope due to a sudden blockage of a pulmonary artery, which is life-threatening and requires immediate medical attention.
- Aortic Dissection: A tear in the aorta's inner layer can lead to syncope among other symptoms, and it is critical to diagnose promptly to prevent fatal outcomes.
- Cardiac Tamponade: Fluid accumulation in the sac surrounding the heart can compress the heart and impede its function, leading to syncope and potentially death if not treated urgently.
Rare Diagnoses
- Subclavian Steal Syndrome: A rare condition where there is a reversal of blood flow in the subclavian artery, which can lead to syncope due to decreased blood flow to the brain.
- Micturition Syncope: Syncope triggered by urination, often due to a sudden drop in blood pressure.
- Defecation Syncope: Similar to micturition syncope but triggered by defecation, also resulting from a sudden drop in blood pressure.