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13 Cards in this Set

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Causes for orthostatic hypotension:

Treatment with LevodopaTreatment with Calcium Channel BlockerHyperaldosteronismHypothyroidismParkinson’s disease

Basics of orthostatic hypotension

Orthostatic (postural) hypotension is an excessive fall in blood pressure (BP) when an upright position is assumed. The consensus definition is a drop of > 20 mm Hg systolic, 10 mm Hg diastolic, or both. Symptoms of faintness, light-headedness, dizziness, confusion, or blurred vision occur within seconds to a few minutes of standing and resolve rapidly on lying down.

Some patients experience falls, syncope, or even generalized seizures.

Exercise or a heavy meal may exacerbate symptoms. Most other associated symptoms and signs relate to the cause.

What is the primary cause of orthostatic hypotension

Orthostatic hypotension is a manifestation of abnormal BP regulation due to various conditions, not a specific disorder. Evidence increasingly suggests that disorders of postural hemodynamic control increase risk of cardiovascular disease and all-cause mortality.


Normally, the gravitational stress of suddenly standing causes blood (½ to 1 L) to pool in the veins of the legs and trunk. The subsequent transient decrease in venous return reduces cardiac output and thus BP.

In response, baroreceptors in the aortic arch and carotid bodies activate autonomic reflexes to rapidly return BP to normal.

The sympathetic nervous system increases heart rate and contractility and increases vasomotor tone of the capacitance vessels.

Simultaneous parasympathetic (vagal) inhibition also increases heart rate. In most people, changes in BP and heart rate upon standing are minimal and transient, and symptoms do not occur.

What comes to play with continued standing

With continued standing, activation of the renin-angiotensin-aldosterone system and vasopressin (ADH) secretion cause sodium and water retention and increase circulating blood volume.

Aetiology of Orthostatic Hypotension

Homeostatic mechanisms may be inadequate to restore low BP if afferent, central, or efferent portions of the autonomic reflex arc are impaired by disorders or drugs, if myocardial contractility or vascular responsiveness is depressed, if hypovolemia is present, or if hormonal responses are faulty


Causes differ depending on whether symptoms are acute or chronic. The most common causes of acute orthostatic hypotension include • Hypovolemia • Drugs • Prolonged bed rest • Adrenal insufficiency

The most common causes of chronic orthostatic hypotension include

• Age-related changes in BP regulation • Drugs • Autonomic dysfunction

What are the neurologic causes


Multiple system atrophy Parkinson disease Strokes (multiple) Spinal cord-

Tabes dorsalis Transverse myelitis Tumors Peripheral -

Amyloidosis Diabetic, alcoholic, or nutritional neuropathy Familial dysautonomia (Riley-Day syndrome) Guillain-Barré syndrome Paraneoplastic syndromes Pure autonomic failure Surgical sympathectomy

What is postprandial orthostatic hypotension

Postprandial orthostatic hypotension is also common. It may be caused by the insulin response to high-carbohydrate meals and blood pooling in the GI tract; this condition is worsened by alcohol intake.

What are the cardiologic causes of orthostatic hypotension


Adrenal insufficiency Dehydration Hemorrhage Impaired vasomotor tone

Bed rest (prolonged) Hypokalemia

Impaired cardiac output

Aortic stenosis

Constrictive pericarditis

Heart failure

Myocardial infarction

Tachyarrhythmias or bradyarrhythmias



*Peripheral venous insufficiency


What are the drugs causing OH


Calcium channel blockers Nitrates Autonomically active

Alpha-blockers (eg, terazosin, doxazosin, phenoxybenzamine) Antihypertensives

eg, clonidine, methyldopa, [rarely] beta-blockers)† Antipsychotics

(particularly phenothiazines) Monoamine oxidase inhibitors (MAOIs) Tricyclic or tetracyclic antidepressants Other

Alcohol Barbiturates Levodopa (in Parkinson disease [rarely]) Loop diuretics (eg, furosemide) Quinidine Vincristine(neurotoxic)

What causes supine orthostatic hypotension

Hyperaldosteronism* Pheochromocytoma*