Differential Diagnosis

The patient's symptoms of high heart rate, chest pain, shortness of breath, dizziness, extreme fatigue, visual disturbances, and tunnel vision, particularly when standing, suggest a range of possible diagnoses. Here is a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Postural Orthostatic Tachycardia Syndrome (POTS): This condition is characterized by a rapid increase in heart rate and other symptoms that occur upon standing, which matches the patient's experience of symptoms worsening when standing and improving when sitting or lying down.

• Other Likely Diagnoses

  • Anxiety Disorder: The symptoms of high heart rate, chest pain, shortness of breath, and dizziness could also be indicative of panic attacks or other anxiety disorders, especially given the episodic nature of the symptoms.
  • Deconditioning or Chronic Fatigue Syndrome: The extreme fatigue and need for rest could suggest deconditioning or chronic fatigue syndrome, particularly if the patient has been less active due to her symptoms.
  • Vasovagal Syncope: Episodes of dizziness, tunnel vision, and seeing 'stars' could be indicative of vasovagal syncope, a condition that leads to fainting spells due to a sudden drop in heart rate and blood pressure.

• Do Not Miss Diagnoses

  • Cardiac Arrhythmias: Conditions like supraventricular tachycardia (SVT) or ventricular tachycardia could cause high heart rates and other symptoms, and are critical to diagnose due to their potential for serious complications.
  • Pulmonary Embolism: Although less likely given the chronic nature of the symptoms, pulmonary embolism can cause sudden onset of shortness of breath, chest pain, and dizziness, and is a life-threatening condition that must be ruled out.
  • Myocardial Ischemia or Infarction: Chest pain and shortness of breath could also be symptoms of heart attack or angina, which are medical emergencies.

• Rare Diagnoses

  • Mitral Valve Prolapse: A condition where the two valve flaps of the mitral valve do not close smoothly or evenly, which can lead to symptoms like palpitations, chest pain, and shortness of breath.
  • Autonomic Dysfunction: Disorders affecting the autonomic nervous system, such as dysautonomia, can cause a wide range of symptoms including those experienced by the patient, though these are less common and would typically be considered after more common causes are ruled out.