SYNCOPE Flashcards
triggered by centrally mediated inhibition of the normal tonic sympathetic
influences, is often associated with excessive vagal
effect and bradycardia (vagal effect)
vasovagal syncope
is meant the withdrawal of sympathetic tone through a
reflex neural mechanism
neurocardiogenic syncope
Neurocardiogenic syncope usually
signifies that the inciting stimulus originates in ________
neural
receptors within the heart
failure of sympathetic innervation of blood vessels and of autonomically activated compensatory responses (reflex tachycardia and vasoconstriction), which occurs with assumption of the upright body position
and leads to pooling of blood in the lower parts of
the body
orthostatic hypotension
caused by a primary diminished
cardiac output because of disease of the heart itself
as in the ____________ bradyarrhythmia attack, severe
aortic or subaortic stenosis, or ischemic heart disease
Stokes-Adams
The vasodepressor faint occurs
(1) in normal health under the influence of strong emotion, particularly in some susceptible individuals (sight of blood or an accident) or in conditions that ___________
e. g., hot, crowded rooms (“heat syncope”), e
favor peripheral vasodilatation,
The vasodepressor faint occurs
2) during a ____________ (especially
of the abdomen or genitalia), as a consequence of
fright, pain, and other factors (where pain is involved, the
vagal element tends to be more prominent in the genesis
of the faint
(3) during ______ in some sensitive persons
painful illness or after bodily injury
exercise
authentic seizure caused by a prolonged period of
brain hypoxia
con vulsive syncope
heightened vagal discharge produced by compression
of the eyeballs _________could produce brief periods of cardiac
arrest and syncope
( oculovagal reflex, a cause of syncope in
acute glaucoma)
T or F
In essence, all the types of
syncope in this category are “vasovagal,” meaning a combination
of vasodepressor and vagal effects in varying
proportions; the only differences are in the stimuli that
elicit the reflex response.
T
Unmyelinated (postganglio sympathec)
fibers cease firing during vasovagal famting at a pomt
when the blood pressure falls below _______ mm Hg
and the pulse, below ________
80/40
60
There is agreement that peripheral vascular resiStance
is greatly reduced just prior to and at th onset of
fainting. This drop in resistance has been attributed to
an initial _______discharge that, at high levels, causes
a ___________
adrenergic
vasodilatation
the drpp in blood
pressure is the result of a transient ut excessive activity
of sympathetic nerves that paradoXIcally leads to vascular dilatation in muscle and viscera from an _______
imbalance between beta-adrenergic and alpha-adrenergic activity
peripherally.
Oberg and Thoren were the first to observe tha the
_______ itself can be the source of neurally mediated
syncope in much the same way as the _______when
stimulated, produces vasodilatation and bradycardi.
left ventricle
carotid sinus
the heart as the afferent
source of vasodepressor reflexes
Bezold-Jansch reflex.
The _______ is the site of most ofthe
subendocardial mechanoreceptors that are responsible
for the afferent impulses to the nucleus tractus solitarius
inferoposterior
wall of the left ventricle
a proclivity to primary neurocardiogenic
syncope can be identified by the finding of
delayed fainting when the patient is placed at __________ position on a tilt table.
After approXImately _________ the blood pressure drps belw100 mm Hg; soon thereafter, the patient complams of diZziness and sweating and subsequently faints.
In contrast,
patients with primary sympathetic failure will faint________
60-degree upright
10 min of upright posture,
s oon
after upward tilting.
Th e ____________ i s normally sensitive t o stretch and gives rise to sensory impulses carried via the nerve of Hering, a tributary of the glossopharyngeal nerve, to the medulla.
carotid sinus
Massage of one of the carotid sinuses or of both alternately, particularly in elderly persons, causes
(1) a reflex cardiac
slowing (sinus bradycardia, sinus arrest, or even atrioventricular
block)-the ________, or
(2) a fall of
arterial pressure without cardiac slowing-the __________
vagal type of response
vasodepressor type of response.
Pathophysio of syncope in Glossopharyngeal neuralgia
Presumably the pain gives rise to a massive volley of afferent impulses
along the ninth cranial nerve, activating the medullary
vasomotor centers via collateral fibers from the nucleus
of the tractus solitarius. An increase in parasympathetic
(vagal) activity slows the heart
consciousness is
lost during or immediately after a forceful swallow.
The
administration of anticholinergic drugs ___________ has abolished these attacks
deglutitional syncope
propantheline 15 mg tid
Pathophysio of micturition syncope
A full bladder causes reflex ______ as the bladder empties, this gives way to ______ which, combined with
an element of postural hypotension, might be sufficient to
cause fainting in some individuals
vasoconstriction;
vasodilatation,
Pathophysio of tussive syncope
This is mainly attributable to the greatly elevated
intrathoracic pressure, which interferes with venous
return to the heart.
______and ________, with resultant cerebral vaso constriction, are possibly contributing factors
Increased cerebrospinal fluid (CSF) pressure
diminished Pco2
the so-called ________ in infants probably represent
reflex vasodepression
pallid attacks
The bedside testing of orthostatic blood pressure is best performed by; having the patient stand quickly and taking readings immediately
and again at _____ and at _________, rather than using
the lying-sitting-standing sequence
1 min
3 min
The maintenance of blood pressure during various levels of activity and with postural changes depends on ____________ in the aortic arch and _______________ in the walls of the heart
pressure-sensitive receptors (baroreceptors)
carotid sinus and mechanoreceptors
Axons from the NTS project to the
________ of the ventrolateral medulla, which
in turn, sends fibers to the _________________
of the spinal cord, thereby controlling vasomotor tone in
skeletal muscles, skin, and the splanchnic bed.
reticular formation
intermediolateral cell column
intolerance of
the standing position accompanied by tachycardia up
to 120 beats per minute or more, but withou t orthostatic
hypotension
Post u r a l O rthostatic Ta c h yca rd i a Sy n d ro m e
In P ri m a ry Auto n o m i c I n s u ffi c i e n cy ( I d i o path i c O rt h ostatic H y p ote n s i o n )
- there is a selective degeneration of neurons in the _________ with denervation of smooth muscle vasculature and ______
- there is a degeneration of
_________ in the lateral columns of gray matter in the spinal cord, leaving postganglionic neurons
isolated from spinal control
sympathetic ganglia
adrenal glands.
preganglionic neurons
There are cases in which neuronal
degeneration is limited to the sympathetic neurons of
the intermediolateral cell columns-_______
the Shy-Drager syndrome.
Cardiac syncope occurs most frequently in patients
with complete atrioventricular block and a heart rate of
___________ (Stokes-Adams attacks, or
Adarns-Stokes-Morgagni syndrome
40 beats or less per minute
If the duration of
cerebral ischemia exceeds_______ there are a few clonic jerks
15 to 20 s,
An inherited syndrome with right
bundle branch block and ST-segment elevation in the
right precordial leads is known to cause syncope and
even sudden death ________
(Brugada syndrome
__________ and ______ from cardiomyopathy
often sets the stage for exertional syncope, because
cardiac output cannot keep pace with the demands of
exercise
Aortic stenosis or subaortic stenosis
Cases of syncope that do occur are usually associated
with multiple occlusions of the large arteries in the thorax
or neck. The main examples are found in patients with
the ______________ in which the
brachiocephalic, common carotid, and vertebral arteries
have become narrowed.
aortic-arch syndrome (Takayasu disease)
Stenosis or occlusion
of vertebral arteries and the _________
are other examples of cerebrovascular diseases
that may cause syncope under the special circumstance
of overuse of an arm
“subclavian steal syndrome”
Fainting also occurs
occasionally in patients with congenital anomalies of the
upper cervical spine____________ or cervical
spondylosis, in which the vertebral circulation is compromised.
(Klippel-Feil syndrome)
This term has been applied to falling spells that occur
without warning and without loss of consciousness or
postictal symptoms
DROP attacks
Pathophysio of drop attack
One potential mechanism is a lapse of tone
in leg muscles during the silent phase of an unnoticed
myoclonic or axterixis jerk
The epileptic attack may occur day or night,
regardless of the position of the patient; syncope rarely
appears when the patient is ________ the only common
exception being the ________
recumbent,
Stokes-Adams attack
Elevated __________ levels have not proved discriminating
enough for routine use in separating seizure from
syncope but remain useful in distinguishing both of these
from other causes of loss of consciousness, particularly
hysteria, in which such elevations do not occur
prolactin
Cardiovascular structures represented in the____________may give rise to seizures that produce cardiac
arrhythmias, leading in turn to syncope
insular
cortex
seizures arising from the _________prolong the QT interval and increase sympathetic tone, thereby lowering the threshold for ventricular arrhythmia, whereas those
arising from the __________ shorten the QT interval
and increase parasympathetic tone, thereby increasing
the risk of vagally mediated syncope
left insula
right insula
Normal response to tilt table test
Upright tilting o n a tilt table may cause, within seconds,
up to 20 or 25 mm Hg drop in systolic blood pressure and 5 to 10 mm Hg in diastolic pressure in normal individuals, usually with only minor symptoms
There are 2 types of abnormal response to upright
tilting: (1)____________ (occurring within moments
of tilting) that slowly progresses with continued upright
posture; this signifies _______________; and
(2) a delayed (up to several minutes) hypotension that appears abruptly at the end of that period and indicates a ________________
early hypotension
inadequate sympathetic tone and baroreceptor function
neurocardiogenic mechanism
The normal response to a 60- to 80-degree head-up
tilt after approximately 10 min is a transient drop in systolic blood pressure_____________, a rise in diastolic
pressure__________ and a rise in heart rate __________
(5 to 15 mm Hg)
(5 to 10 mm Hg),
(10 to 15 beats per minute)
