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Information For
Patients Who Have Been Scheduled To Undergo Diagnostic Cardiac
Catheterization Or Percutaneous Transluminal Coronary Intervention
(Angioplasty)
A clinical decision was made that the performance of a cardiac
catheterization is felt to be necessary to provide additional
diagnostic information to help make appropriate decisions, which
will assist in your cardiac care. The decision to perform cardiac
catheterization may be based upon your symptoms, your coronary risk
profile, additional suspicious clinical data [i.e. an EKG
abnormality], specific non-invasive diagnostic testing, and/or due
to additional concern expressed by you or a family member with the
knowledge that coronary heart disease is generally felt to be a
common dangerous, yet treatable condition). A decision to proceed
directly to cardiac catheterization (without preliminary diagnostic
testing, or even if prior testing was normal) may be both reasonable
and prudent, if you have clinical signs or symptoms, which are
either suspicious or recurrent.
Specific non-invasive diagnostic testing may have been performed at
the request of your primary care physician, or at our discretion.
This testing includes all forms of “stress testing” (with or without
myocardial perfusion imaging) to assess for the presence of
arteriosclerotic coronary heart disease. Such testing can include
the use of an exercise test (using a treadmill or bicycle
ergometer), or a pharmacologic agent (such as adenosine or
dobutamine). These studies are among the most commonly used for this
purpose. The use of perfusion imaging markedly improves the
diagnostic accuracy of these studies. The sensitivity and
specificity of perfusion imaging is 95% and 90% respectively. That
suggests that these studies are reasonably accurate for coronary
disease diagnosis (but not perfect). We most often use the findings
of such a study to determine which patients may benefit from
undergoing diagnostic cardiac catheterization. An abnormality may
have been noted on your imaging study that is sufficient enough to
recommend a diagnostic cardiac catheterization.
A cardiac catheterization is done in a cardiac catheterization
suite. The only hospitals that currently have this type of equipment
in the Scranton area are CMC, and Mercy Hospital. For hospitalized
patients, the catheterization (cath) is usually performed urgently
or emergently. For outpatients, or if an individual’s clinical
findings are less pressing, the cath can be done electively (as an
outpatient). If an outpatient cath has been suggested, we request
that you contact our office (telephone number is noted above); to
have your cardiac cath scheduled (at your earliest convenience).
Generally, it would be best to arrange to have the procedure done
within the next few weeks.
On the day of your procedure, you should plan to arrive about an
hour ahead of your scheduled procedure time. This will allow time to
prepare you for the cath. An intravenous line will be inserted, and
you will be provided with appropriate sedation for your procedure;
you will not be totally asleep however.
When your procedure begins, you will be brought into a cardiac cath
suite (which is effectively a modified X-ray suite). The staff will
do all that is possible to see to your comfort. A local anesthetic
will be administered to your “groin”. This is a “numbing” of the
skin in or near the crease where your thigh meets your hip. There
should be no more discomfort at any time during the study than this
numbing from local anesthesia (as there are no nerve endings
anywhere else that the catheter will traverse). A needle will be
passed to the artery that runs near the surface beneath the numbed
skin to obtain access to an artery.
A sheath will be placed into the artery (a hollow tube with a
stopper – not much larger in diameter than a strand of thin
spaghetti). A catheter (which is nothing more than a long flexible
small hollow tube) is passed through the sheath, and positioned with
its tip just within the origin of the coronary arteries (These are
the tiny vessels which run along the outside of the heart to provide
nourishment to the heart muscle and keep it healthy. It is these
coronary arteries that tend to accumulate cholesterol plaques – and
cause blockages; which we refer to as arteriosclerotic coronary
heart disease.).
A radiocontrast agent (iodine-containing dye) will be injected
through the catheter while a high-speed movie camera is activated
through the X-ray machine. This allows the radiocontrast (dye) to
run-off down the coronary arteries; allowing us to opacify the
lumen, and locate any of the blockages that are suspected to be
present. We will repeat the dye injection and digital movie imaging
in several positions, so that all of an individual’s coronary
vessels can be evaluated from different angles.
The final image that we take is called a “ventriculogram”. A
catheter will be positioned within the left ventricular chamber and
a spurt of “dye” will be given so that we can assess the left
ventricular size and the wall motion of the ventricle.
At the end of the study, a dye picture will be taken of the femoral
artery (where the sheath is inserted). Most often, a vascular
closure device (either a collagen plug or a suture) will be used to
close the artery in the groin area. This allows a patient to be up
and around much sooner (usually within an hour or two). The entire
time of the catheterization should require no more than fifteen to
thirty minutes.
If no abnormality is identified (or if it is felt that a patient
does not require additional therapy at that time), you should expect
to leave the hospital within one-to-two hours after the completion
of the procedure.
If an abnormality is identified that is deemed “fixable” (many
blockages can be repaired or corrected at the same time through the
catheter), the cardiologist may elect (with your permission) to
proceed to an angioplasty.
Angioplasty is the vessel repair procedure that may ensue in
individuals that require it. Angioplasty technically means “vessel
modification”. The prototype procedure (developed more than 30 years
ago) involved the passage of a guidewire through the catheter down
the coronary artery and across the blockage. The guidewire is not
much larger around than a human hair. It has a soft supple tip and a
stainless steel shaft. A tiny catheter is passed coaxially over the
guidewire to the point of the blockage. The tiny catheter has an
inflatable balloon at its tip that can be filled with dye. The
inflated balloon resembles a “hot dog” (but is infinitely smaller –
no larger than the true diameter of the coronary vessel). It
stretches open the vessel at the point of the blockage. The balloon
is then deflated and removed (effectively restoring blood flow down
the vessel).
Many technological modifications and improvements have been made in
angioplasty over the past few decades. There now exist a wide
variety of specialized catheters for opening vessels and/or plaque
removal. These can include laser catheters, shaving or cutting
catheters, suction catheters, grinding catheters, and stents.
A stent is a tiny metallic mesh tube that can be mounted on a
coronary balloon, or can be of a “self-expanding” variety that comes
housed in a sheath, which is withdrawn, to allow the stent to expand
to its natural position. Stents have demonstrated the ability to
“prop-open” a vessel, provide for an improved angiographic
appearance, and reduce both potential procedural complications and
long-term results. Because of this, most cardiologists prefer to use
a stent as part of an angioplasty procedure, if possible.
The risks of the diagnostic cardiac catheterization include an
extremely low risk of serious complications (stroke, heart attack,
and death). Again, these complications are relatively rare (less
than 0.1%). Other minor complications can occur more frequently (but
are still rather uncommon), and include; vascular injury
[potentially requiring repair and/or transfusion] (less than 2%),
radiocontrast allergy (less than 2%), and kidney damage [related to
radiocontrast use] (less than 2%).
If an angioplasty is performed, the procedural risks are greater
(which is understandable, as an angioplasty involves a mechanical
modification or correction of a coronary plaque that is causing a
blockage, and a potential danger in itself). These complications
include those that are mentioned above (some already noted have an
increased incidence); specifically, the incidence of death is less
than 1%, and the incidence of heart attack is 3%. Additional
potential risks (with angioplasty) include: coronary vessel
dissection (5-10%), abrupt coronary closure (less than 5%), coronary
perforation (1-2%), hemopericardium with or without cardiac
tamponade [extravasation of blood into the pericardial sac exerting
an outward pressure on the heart] (1%), emergency coronary bypass
operation (less than 0.1%), and restenosis [a recurrence of a
blockage] (~30% with routine angioplasty, ~15% with the use of a
stent, and ~1-3% with a “drug-eluting” stent).
In the unusual event that a complication occurs, it may be necessary
for your cardiologist to perform additional procedures at his
discretion to attempt to protect your heart and your life. These
procedures may include: insertion of an intra-aortic balloon pump (a
mechanical pump to assist with heart function while other measures
are considered or undertaken to provide additional stabilization),
insertion of a temporary trans-venous pacemaker (to assist your
heart rhythm), and/or performance of a pericardiocentesis (insertion
of a needle and possibly also a catheter into the pericardial sac to
remove fluid). During such a situation (although uncommon), it may
also be necessary for your cardiologist to select additional
physicians (anesthesiologist, cardiothoracic surgeon, etc.) to
assist with your breathing and subsequent care.
The overall success rate of angioplasty in the hands of an
experienced operator is about 95-98%. If an angioplasty is
performed, you can expect to remain in the hospital overnight and be
released the following morning (barring any other complicating
issues). |
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