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Re: Test Results

Posted By CCF CARDIO MD-APS on August 12, 1998 at 16:18:30:

In Reply to: Test Results posted by Pam on August 12, 1998 at 15:25:30:






My mother was recently diagnosed with coronary artery disease & had the following
procedures done: Right heart cath, a retrograde L heart cath, L ventricular cineangiocardiogram
and selective arteriography via the r groin approach. The doctor came out &
explained everything but I did not understand some of the findings. I am an RN but have limited knowledge
in cardiology. What does the ejection fraction mean & what is the normal range?  Also, what is the significance
of measuring the wall motion & what are the normal percentages for the anterobasal, anterolateral, apical,
diaphragmatic & posterobasal?  Also what is troponin, what does it measure & what is the normal value?
Thank you.
Pam



____


Dear Pam,
The ejection fraction is the percentage of blood ejected with each heart beat.
Much to many lay persons suprise is that the normal heart does NOT pump out
100% of all the blood contained in the ventricles with each beat.  So a normal
ejection fraction is variable (dependent on the loading conditions or overall
volume in the patients system, as well as dependent on the study and the person
doing the study); regardless the normal range is usually around 55-60% as  being
normal.  Now a low ejection fraction can have many causes and one way that
cardiologists investigate the culprit is by looking at the walls of the heart in
sections (it is all one continuous muscle mass however) that actually more or less
correspond to their blood supply.  For example the left anterior descending artery
(LAD) that comes down the front wall of the heart supplies the most important wall
of the heart and that is the anterior wall, the branches of the LAD supply the lateral
wall and sometimes the distal LAD will even supply the distal inferior wall of the heart.
Well it easy to see then how we can infer that in a patient with a decrease ejection fraction
and a poorly functioning wall has probably had significant compromise of blood flow to that wall
and this then implies coronary artery disease in that vessel.  If a wall  does not
work or function at all, this likely represents a prior heart attack/MI.  Now there are many
patients who have a low ejection fraction based on what is called global dysfunction and that is when
all the walls are equally not functioning well, kind of looks like the muscle has
just lost it's "umph" and this is termed cardiomyopathy ( of course there are many causes of this
condition.)  As for the expected percentages of each particular wall or section of heart
muscle, there is no standard, rather there is the expectation that the wall contracts or it does not
in a mild, moderate, or severe manner which when all put together gives you and overall ejection fraction.
As I said before the anterior wall is the most important wall, partially because it is a larger portion of
the heart muscle and so if someone has a anterior MI that incapacitates their entire anterior wall their ejection
fraction is most likely going to be lower than that of the person with just a lateral wall MI.  
Troponin is a test of myocardial injury, it is the second generation CPK measurement in a sense, and the normal
value of course depends on the lab that performs the test.  The last value I remember seeing for a normal
troponin was <0.3, at which hospital this was I am not sure.  An elevated troponin simply indicates that there
has been heart muscle damage and the patient deserves and evaluation for coronary artery disease.  Good Luck to you and your
mother.
Information provided in the heart forum is intended for general medical informational purposes only, actual
diagnosis and treatment can only be made by your physician(s).  

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