Fainting also known as Syncope of "black out" is defined as a
condition of sudden loss of consciousness followed by the return to full
wakefulness in a short duration as a result of abnormally low blood
pressure. In most cases, it is caused by hypotension, with blood
pressure that's lower than 90/60 mmHg.(1). Even though Low blood pressure
has mainly been regarded as good health for people who exercise, but
recent studies have indicated an association with depression in elderly
people. there are epidemiological evidence for an association of low blood pressure
with anxiety and depression, which is not caused by cardiovascular
disease.(2). In some case, severely low blood pressure can seriously
impair
adequate blood flow to vital organs and a life-threatening condition
called shock.
Causes and risk factors
Causes of fainting may be a result of your heart rate and blood vessels
can't react fast enough when your body's need for oxygen changes
1. History of
any cardiovascular disease and and cardiac arrhythmias
In a study of consecutive patients evaluated for syncope from 1996 through 1998 at an academic medical center, we documented causes, clinical characteristics, and recurrence of syncope while driving. Of 3877 patients identified, 381 (9.8%) had syncope while driving (driving group). Compared with the 3496 patients (90.2%) who did not have syncope
while driving, the driving group was younger (P=0.01) and had higher
percentages of male patients (P<0.001) and patients with a history of
any cardiovascular disease (P=0.01) and stroke (P=0.02). Syncope while driving was commonly caused by neurally mediated syncope
(37.3%) and cardiac arrhythmias (11.8%). Long-term survival in the
driving group was comparable to that of an age- and sex-matched cohort
from the Minnesota population (P=0.15). Among the driving group, syncope
recurred in 72 patients, 35 of whom (48.6%) had recurrence >6 months
after the initial evaluation. Recurrences during driving happened in 10
patients in the driving group, 7 of which (70%) were >12 months
after the initial evaluation.(4)
2. Low blood pressure
researchers suggested that Syncope due to orthostatic hypotension (OH) refers to loss of consciousness caused by hypotension
induced by the upright position; it is an important risk factor for
fall-related physical injuries, especially in the elderly adults(5). Other report indicated that eventhough Low blood pressure has mainly
been regarded as good health for people who exercise, but recent studies
have indicated an association with depression in elderly people. there
are epidemiological evidence for an association of low blood pressure with anxiety and depression, which is not caused by cardiovascular disease.
3. Parkinson's disease and neurological comorbidity in olders
Low blood pressure is considered as a major cause of fainting of patient
older than 65 years as a result of Parkinson's disease and
neurological comorbidity. (5)
4. Medication
there is a report that in patients with AD treated with donepezil, a noninvasive evaluation identified a probable cause of syncope
in over two-thirds of patients. Cardiovascular abnormalities were
predominant. Noninvasive evaluation is recommended before discontinuing
treatment with cholinesterase inhibitors in patients with AD and
unexplained syncope.(6)
5. Hemodynamic ischemia
There a report that a patient with convulsive syncope whose convulsive movements seemed to be associated with transient hemodynamic ischemia
in the basal ganglia. In Single-photon emission computed tomography
(SPECT, a significant decrease in blood flow was revealed in the
anterior part
of the left basal ganglia, bilateral frontal areas, and right cerebellar
hemisphere. An alteration in the functional balance between the basal
ganglia and the cerebral cortices may play a role in the generation of
convulsive movements in patients with convulsive syncope.(7)
6. Vertebrobasilar disease
Vertebrobasilar disease is a broad classification describing the
condition where there is an insufficient delivery of blood flow via the
vertebral and/or basilar arteries to the brain.(8)
7. Vasovagal (situational) syncope
A vasovagal episode or vasovagal response or vasovagal attack (also called neurocardiogenic syncope) is a malaise mediated by the vagus nerve. When it leads to syncope or "fainting", it is called a vasovagal syncope, which is the most common type of fainting(9)
8. Deglutition syncope
Deglutition suncope is defined as a loss of consciousness on
swallowing. There are report that a 49-year-old woman was referred to
the ENT department with a 1.5-year
history of dysphagia accompanied by globus sensation and regurgitation
as well as recurrent syncopal attacks associated with swallowing solid
foods(10) and a case of swallow syncope associated with cold beverage
ingestion(11) and a woman who faints when she eats and drinks(12) may be
as a result of an ambulatory electrocardiogram revealed atrial and
ventricular
asystoles immediately after swallowing (13)
9. Cardiac syncope
Structural cardiac abnormalities may cause syncope include cardiac obstructions, pulmonary hypertension, and myocardiopathy. Children with congenital heart disease who experienced syncope
should always be referred to a specialist. Primary arrhythmias which
are easily diagnosed on ECG are complete atrio-ventricular block and
Wolff-Parkinson-White syndrome. "Channelopathies" such as the long OT
syndrome and catecholaminergic ventricular tachycardia are increasingly
recognized in children, carry a high risk of sudden death and deserve a
complete work up, including familial screening and lifelong treatment
with beta-blockers(14)
10. History of diaphoresis In the investigation of whether the pattern of presyncopal prodromal symptoms can predict the recurrence probability of vasovagal syncope, fifty-four patients (68.4%) reported at least one of the four main prodromal symptoms. Median syncopal +/- presyncopal spells were 4 episodes. Forty-two patients (53.2%) experienced recurrence of syncope
or presyncope during the follow-up period. In recurrent symptomatic
patients, diaphoresis had been more significantly reported in their past
medical history (p = 0.018) and they had more syncopal spells before
TTT (p = 0.001). Age, gender and type of TTT response did not have any
effect on the recurrence of VVS.(15)
11. Prolonged exercise
Some researchers suggested that the magnitude of exercise-induced hypotension (post-exercise hypotension; PEH), and the hypotensive response to postural change (initial orthostatic hypotension; IOH) are predictors of syncope post-exercise, but research team from the University of Otago, found that endurance athletes who present with greater hypotension are not necessarily at a greater risk of syncope than those who present with lesser reductions in BP.(16)
12. Chiari type I malformation (CMI)
Chiari type I malformation (CMI) is a congenital hindbrain anomaly
characterized by downward displacement of the cerebellar tonsils through
the foramen magnum. Chiari type I malformation often presents with a
complex clinical picture and can be sporadic or linked to a variety of
genetic conditions. (17)
13. Low blood sugar
In the study of Syncope and Hypoglycemia posted in International Journal
of Clinical Medicine, 2011, 2, 129-132 doi:10.4236/ijcm.2011.22023
Published Online May 201, showed that hypoglycemic syncope should be
sus-pected in older diabetic patients with preserved postural tone,
usually but not always using insulin therapy, who show a slow recovery
from transient loss of consciousness with persisting neurological
impairment and low blood glucose levels.(18)
14. Dehydration
Dehydration is defined as a condition of the excessive loss of body
fluid. of which can lead to symptoms of decreased blood pressure
(hypotension), and dizziness or fainting(19)
15. Family history
In the study conducted by Johns Hopkins Bloomberg School of Public Health, researchers showed that family history of fainting
is not a risk factor for adult-onset NMH in fatigued veterans. Our
findings may differ from other studies of familial aggregation in NMH
because of study methods or because NMH-fatiguers may differ from
NMH-fainters.(20)
16. Pregnancy
A 23-year-old woman at 34 weeks' gestation developed recurrent syncope
due to profound sinus arrest captured on electrocardiography. Syncopal
events occurred in the same sitting position. An echocardiogram revealed
severe collapse of the inferior vena cava each time the patient changed
her posture from a supine to a sitting position, which was related to
the syncope.(21)
17. Etc.
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Sources
(1) http://www.nhlbi.nih.gov/health/dci/Diseases/hyp/hyp_whatis.html
(2) http://www.ncbi.nlm.nih.gov/pubmed/17183016
(3) http://www.ncbi.nlm.nih.gov/pubmed/19587129
(4) http://www.ncbi.nlm.nih.gov/pubmed/19720940
(5) http://www.ncbi.nlm.nih.gov/pubmed/19349588
(5a) http://www.ncbi.nlm.nih.gov/pubmed/17183016
(6) http://www.ncbi.nlm.nih.gov/pubmed/16060718
(7) http://www.ncbi.nlm.nih.gov/pubmed/21706831
(8) http://surgery.med.umich.edu/vascular/patient/disease-specific/vertebrobasilar.shtml
(9) http://en.wikipedia.org/wiki/Vasovagal_response
(10) http://www.ncbi.nlm.nih.gov/pubmed/22286303
(11) http://www.ncbi.nlm.nih.gov/pubmed/22493619
(12) http://www.ncbi.nlm.nih.gov/pubmed/21704625
(13) http://www.ncbi.nlm.nih.gov/pubmed/16286732
(14) http://www.ncbi.nlm.nih.gov/pubmed/16705918
(15) http://www.ncbi.nlm.nih.gov/pubmed/18810720
(16) http://www.ncbi.nlm.nih.gov/pubmed/20886226
(17) http://www.ncbi.nlm.nih.gov/pubmed/21589844
(18) www.scirp.org/journal/PaperDownload.aspx?paperID=5203
(19) http://en.wikipedia.org/wiki/Dehydration
(20) http://www.ncbi.nlm.nih.gov/pubmed/16920765
(21) http://www.ncbi.nlm.nih.gov/pubmed/14609615
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