Differential Diagnosis
- Single most likely diagnosis
- Left ventricular outflow obstruction: The patient's symptoms of dizziness and chest tightness on exertion, along with the physical examination findings of a delayed carotid upstroke, a laterally displaced point of maximal impulse, and a grade 3/6 midsystolic murmur best heard at the cardiac base, are highly suggestive of left ventricular outflow obstruction, likely due to hypertrophic cardiomyopathy or aortic stenosis. The murmur and the delayed carotid upstroke are classic signs of aortic stenosis, which can cause syncope due to obstructed blood flow.
- Other Likely diagnoses
- Atrial arrhythmia: Although less likely given the specific physical examination findings, atrial arrhythmias can cause dizziness and syncope, especially if they lead to significant bradycardia or tachycardia.
- Carotid artery stenosis: This could potentially cause syncope through embolic events or significant carotid artery disease leading to decreased cerebral blood flow. However, the absence of carotid bruits and the presence of other cardiac findings make this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cryptogenic embolization: Although the patient's presentation does not strongly suggest a primary embolic event, any cause of syncope could potentially be due to an embolic phenomenon, especially if there's an underlying cardiac source of embolism (e.g., atrial fibrillation not detected at the time of examination).
- Carotid artery hypersensitivity: This is a less common cause of syncope but can be due to hypersensitive carotid sinus baroreceptors leading to bradycardia and/or vasodilation in response to carotid sinus massage or other stimuli.
- Rare diagnoses
- Other structural heart diseases (e.g., cardiac tumors, congenital heart diseases) that could cause outflow obstruction or other mechanisms leading to syncope.
- Neurocardiogenic syncope: Although common, the patient's exertional symptoms and specific cardiac findings make this less likely compared to a primary cardiac cause.