2) Orthostatic Hypotension 5-29 % of all causes syncope
    Aging changes in physiology that predispose to orthostatic hypotension:
  
 - decrease in B-adrenergic responsivenss
    - decrease in baroreflex:
      (which should increase heart rate and vasoconstrict)

Definition:  A decline in systolic BP > 20 mm Hg with supine to standing &/or increase in heart rate > 20 beats/min.
Technique: measure BP & pulse: -lying for > 5 minutes then sitting, then, standing for 1 and 3 minutes
Causes : a) Volume loss
b) Medications
c) Situational
d) Primary Autonomic Disease
e) Secondary Autonomic Disease
f) Adrenal Insufficiency
 
a) Volume Loss

blood loss

fluid loss
(examples: diarrhea, sweating, diuresis, dehydration)

b) Medications;

antihypertensives

antiparkinsonian

alcohol

B-blockers

antianginals

vasodilators

anticholinergics

 c) Situational

(many of these involve Vasovagal mechanisms also)

micturition

postprandial*

cough

carotid sinus sensitivity

*"36 % elderly NH pop. had orthostatic hypotension postprandially BUT: only 2 % had symptoms from it.

d) Primary Autonomic Disease

Idiopathic
Multi-System Atrophy(Shy-Dragger)
Parkinson’s disease

e) Secondary Autonomic disease

1) Neuropathy

2)Central Nervous System disease (CNS)

1) Neuropathic  

DM,

auto-immune disease

Vitamin B 12 deficiency

Syphilis

amyloid

cancer

Renal failure

Heavy metal toxicity

alcoholism

porphyria

hypothyroid

Etc.

2)Central Nervous System disease (CNS) 

CVA’S,

Multiple Sclerosis (MS)

Spinal cord lesion

Wernike’s

DIAGNOSIS: of Orthostatic Hypotension

The "Gold Standard" for diagnosis

Proven orthostatic hypotension (OH) (see definition above) and symptoms reproduced

via:     1) clinically demonstrated (OH) with symptoms

or

2) Tilt table testing* with provocation of symptoms

The "Fall-Back Position" for diagnosis

Proven orthostatic hypotension and strong suspicions

based on consistent history

* Tilt table testing usual techinigue:

1st Passive testing:
Technique; fasting, serial BP’s in various tilt positions up to 60 degrees with patient standing still

2nd Isoproteronol infusion:
Technique: as above plus infusion of isoproteronol
Positive: demonstrates drop in BP> 20 mm Hg and symptom reproduction

Effectiveness:
gave diagnosis in 53% of unknowns after usual workup.