Anxiety or Panic Disorder: This condition often presents with symptoms of palpitations (hearing one's heartbeat), dizziness, and anxiety. The physical symptoms can be triggered by stress or anxiety, making it a common cause for these complaints.

Mitral Valve Prolapse: A condition where the mitral valve does not close properly, leading to palpitations and sometimes dizziness due to changes in blood flow.
Hyperthyroidism: An overactive thyroid gland can cause an increase in heart rate, leading to palpitations and potentially dizziness due to the body's increased metabolic state.
Dehydration or Electrolyte Imbalance: Dehydration or an imbalance of essential electrolytes like potassium or sodium can lead to palpitations and dizziness due to the heart's increased workload and potential for arrhythmias.

Cardiac Arrhythmias (e.g., Atrial Fibrillation): Abnormal heart rhythms can cause palpitations and dizziness. Missing this diagnosis could lead to severe complications, including stroke or heart failure.
Hypertrophic Cardiomyopathy: A condition where the heart muscle becomes thickened, potentially leading to obstructed blood flow and increased risk of sudden cardiac death. Palpitations and dizziness can be presenting symptoms.
Pulmonary Embolism: Although less common, a pulmonary embolism can cause palpitations and dizziness due to the blockage of blood flow in the lungs, which is a life-threatening condition.

Pheochromocytoma: A rare tumor of the adrenal gland that leads to excessive production of adrenaline, causing palpitations, dizziness, and potentially life-threatening hypertension.
Cardiac Tumors: Rare tumors of the heart can cause obstructive symptoms leading to palpitations and dizziness.
Neurocardiogenic Syncope: A condition that affects the nervous system's regulation of heart rate and blood pressure, leading to fainting spells that might be preceded by palpitations and dizziness.