What is a Tilt Test?
What is Neurally Mediated
How is Tilt Test performed?
How to prepare for the test?
How long does it take?
How safe is it?
What information is provided by Tilt
How quickly will I get the results
of the test?
What is a
Tilt Test? A Tilt Table Test or TTT is widely
used in making the diagnosis of Neurally (pronounced
new-rully) Mediated Syncope (pronounced syn-cup-ee)
or NMS. Both of them are discussed below.
What is Neurally Mediated
Syncope (NMS) and why do these patients pass out?
NMS is a condition that can occur in a wide
range of people, many of whom do not have any other
associated cardiovascular problems. These patients
give a history of repeatedly having syncope (passing
out spells) over the course of several years. Some
of these spells may be preceded by a hot sensation
or nausea but many come on without any warning. The
patient may fall to the ground and recover consciousness
quickly and without any further problems. The episodes
of syncope may occur at church, in the grocery store,
while a blood specimen is being drawn, or while sitting
quietly at home, etc. Surprisingly, the majority of
the patients never sustain serious injuries and the
diagnosis may go undetected for decades. Patient's
get used to having "faints" and life goes
on! The availability of the Tilt Test, its wide success
in establishing the diagnosis of NMS, and effective
treatment for NMS has resulted in the well deserved
popularity of the test.
understand this phenomenon, we must first examine
how the nervous system of the body functions. During
our daily activities, our heart rate (HR) and blood
pressure (BP) constantly rise and fall to meet the
needs of the body. The HR and BP are lower at rest,
while the HR picks up and BP is elevated during emotional
stress and exercise. The control of the HR and BP
are under the domain of the sympathetic (pronounced
sim-pa-thetic) and parasympathetic nervous system.
The former increases the HR and BP while the latter
reduces them. To simplify this concept, let us imagine
that the body is an automobile. Pressing the accelerator
pedal would make the car work harder and go faster.
In contrast, pressing the brake pedal would slow the
car down. Thus, the sympathetic nervous system behaves
like an accelerator for the body while the parasympathetic
system functions like a braking system. You with me?
Normally, the sympathetic and parasympathetic
nervous system work together in a very efficient and
cooperative manner. Just like a good driver, the accelerator
and brake pedals are used efficiently (one being slowly
pressed while the other is smoothly released). The
car slows down and speeds up so smoothly that one
does not recognize the change. Similarly, our HR and
BP goes up and down without us being aware of it.
From time to time, this system breaks down in people
with NMS. It is almost as if the accelerator pedal
remains in the control of the car driver while the
braking system is occasionally turned over to an extremely
nervous "back seat driver." This spells
trouble! Now, if the "car" accelerates too
rapidly (HR and BP goes up), the back seat driver
panics and SLAMS the brake. The HR and BP (either
singly or together) drop suddenly and severely. This
reduces blood supply to the brain and the patient
passes out. The back seat driver then steps off the
brake pedal, the HR and BP increases, blood flow is
restored and the patient awakens.
How is the Tilt Test
Performed? The patient is hooked to an EKG
machine and a BP monitor. The HR and BP are constantly
monitored during the procedure. An intravenous (IV)
line is placed in the arm. Large patches are also
applied to the patient's chest.
These patches are connected to
an external pacemaker and turned on if the patient's
HR slows down and does not pick right up (in the majority
of cases the slow HR is transient and the external
pacemaker is only a precautionary measure).
The patient lays on a swivel table
in a flat position. Safety straps are applied across
the chest and legs to hold the patient in place.
After obtaining the baseline HR
and BP, the motorized table is tilted up to an angle
of 80 degrees. This simulates going from a flat (supine)
to a standing or upright position. The change in position
causes the HR and BP to rise and the patient's response
is noted. Depending upon the physician and the protocol
of a given laboratory, the duration of time spent
in the supine and upright position can vary from 5
to 30 minutes.
If nothing happens, the table
is returned to the flat position and an intravenous
infusion of isoproternol (Trade name = Isuprel) is
started. This medicine increases the HR and BP. This
effect is similar to that produced by our own natural
adrenaline release. As you may have gathered, the
test is now simulating what happens when the sympathetic
nervous system is stimulated and the "accelerator"
is pressed. The tilt table is then raised back up
to 80 degrees and the IV medication continued.
A stop clock in the room is used
to keep track of time. If an abnormal result is not
seen, the table is lowered and then raised back up
after increasing the dose of the IV medicine. In patients
with NMS, the increase in HR and BP is usually sufficient
to cause "panic in the back seat driver"
(parasympathetic nervous system). When this happens,
the HR, BP or both drop suddenly and dramatically
as the parasympathetic system "slams the brake
pedal.". The patient gets dizzy and passes out.
Thus, TTT succeeds in simulating a real life situation
and establishes the cause of recurrent black out spells.
With the above changes, the test is considered positive.
The IV medicine is immediately stopped and the patient
returned to the flat or supine position. Within a
few seconds, the patient regains consciousness and
both the HR and BP return to normal. The patient is
observed for 10 to 20 minutes and then disconnected
from the equipment.
How to prepare for the
Tilt test? Check with your physician to see
if any of your medications need to be held. You should
not eat or drink after midnight to reduce the risk
of nausea and vomiting during the test. Try and wear
a blouse or shirt to expedite preparation for the
How long does the Tilt
test take? The test generally takes a total
of 1 1/2 hours. This includes preparation, the actual
test and the recovery phase. Please make sure that
somebody can drive you home after the test.
How safe is a Tilt test?
The test is fairly safe, although it can be dramatic
for the patient if the test is positive and causes
a black out spell. Not a very pleasant circumstance!
However, the patient needs to recognize that this
denotes a positive response and opens the door to
the addition of extremely effective medications that
may dramatically reduce or totally eliminate the patient's
recurrent black out spells. In rare cases, the test
may produce persistent abnormal heart rhythm and patients
with coronary artery disease may occasionally experience
lingering chest discomfort. Experienced staff and
equipment are on hand to handle these potential complications.
What information is provided
by the Tilt test? The tilt test helps to
confirm the diagnosis of NMS. This is extremely important
because there is effective treatment for the condition
which can either totally eradicate or dramatically
reduce the frequency and intensity of symptoms (dizziness
and black out spells). Recent research studies have
also shown a correlation between chronic fatigue syndrome
(CFS) and NMS. Treatment aimed at NMS has been shown
to be beneficial in many patients with CFS (if they
have a positive tilt test). The use of beta-blockers
is most commonly employed in the treatment of NMS.
The beta-blockers acts as a "governor" on
a carburetor. The motor does not "rev up"
as much (HR and BP does not increase drastically)
and the back seat driver (parasympathetic system)
remains calm and does not slam on the brakes. Other
drugs that have shown benefit include aminophylline,
disopyramide and certain anti-depressants serotonin-uptake
will I get the results of the Tilt Test?
The tilt test results are generally provided to you
as soon as it is completed. Changes in your medications,
if indicated by the results of the test, may be discussed
at the same time or during a subsequent office visit.