Differential Diagnosis for a Young Man with Palpitations and Normal Vital Signs

Single Most Likely Diagnosis

• Supraventricular Tachycardia (SVT): This condition is characterized by a rapid heart rate, often between 160-280 bpm, which matches the patient's pulse rate of 180bpm. The presence of a regular rhythm, normal S1 and S2 heart sounds, and the absence of prior cardiovascular history make SVT a likely diagnosis.

Other Likely Diagnoses

• Atrial Fibrillation: Although less likely given the regular rhythm suggested by the fixed pulse rate, atrial fibrillation can sometimes present with a rapid, regular ventricular response, especially in younger individuals or those with a controlled ventricular rate.
• Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC): This condition could lead to ventricular arrhythmias, including tachycardia, but it is less common and typically associated with other symptoms or family history.
• Paroxysmal Supraventricular Tachycardia (PSVT): Similar to SVT, PSVT involves episodes of rapid heart rate that start in the upper chambers of the heart, which could fit the patient's presentation.

Do Not Miss Diagnoses

• Ventricular Tachycardia (VT): Although less likely in a young individual without prior cardiovascular history, VT is a life-threatening condition that requires immediate recognition and treatment. The key distinguishing feature from SVT is the wider QRS complex on ECG, which is not mentioned but crucial for differentiation.
• Wolff-Parkinson-White (WPW) Syndrome: This condition involves an accessory electrical pathway in the heart that can cause the heart to beat too quickly. It can lead to SVT but also has a risk of degenerating into a more dangerous arrhythmia.

Rare Diagnoses

• Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT): A rare genetic disorder that can cause life-threatening arrhythmias, typically triggered by physical activity or emotional stress.
• Long QT Syndrome: A condition affecting the heart's electrical system, which can lead to sudden, uncontrollable, dangerous arrhythmias, often triggered by exercise or stress.

Each of these diagnoses requires consideration of the patient's clinical presentation, ECG findings, and potentially further diagnostic testing for accurate diagnosis and appropriate management.