A. Cardiovascular

1. Reflex
   1. Carotid sinus
   2. cardioinhibitory, vasodepressor
      1. central
   3. Vasovagal
   4. cough, micturition
      1. defecation, post-prandial
      2. valsalva, sneeze
2. Orthostatic Hypotension
   1. Dehydration / Blood Loss
   2. Autonomic insufficiency
   3. Adrenal Insufficiency
3. Mechanical (Obstructive)
   1. Aortic Stenosis
   2. Hypertrophic cardiomyopathy
   3. Pulmonary Embolism, HTN, Stenosis
   4. Aortic Dissection
   5. Myocardial Infarction
4. Electrical (arrhythmia)
   1. AV Block
   2. Sick Sinus Syndrome
   3. Arrhythmia (Ventricular vs. Supra-)
   4. Long QT syndrome

B. Neurologic

1. Transient Ischemic Attack (TIA)
2. Seizure
3. Takayatsu (Giant Cell) Arteritis
4. Intermittent Pressure Hydrocephalus
5. Psychiatric - panic disorders, depression
6. Subclavian Steel Syndrome
7. Vertebrobasilar insufficiency

C. Metabolic

1. Hypoglycemia
2. Hypoxia
3. Shock
4. Hyperventilation
5. Anemia
6. Alcoholic

References

1. Manolis AS, Linzer M, Salem D, Estes NA 3d. 1990. Ann Intern Med. 112(11):850