Percutaneous
transluminal coronary angioplasty (PTCA)
PTCA is a non-surgical procedure performed under
X-ray guidance that can reduce a coronary arterial blockage
from 70-90% to 20-30%. [Kern
et al, 1997; Takeuchi
and Himeno, 1998; Muller
et al, 1990]. The patient is administered a mild sedative
and a catheter with a deflated balloon mounted on the tip
is inserted into the major vessel of the groin or arm under
local anaesthetic. X-ray is used to guide the catheter up
to the heart. In the middle of the balloon is a radiopaque
marker, which is used to line up the balloon with the blockage.
The balloon is inflated using a small hand-held pump filled
with dye. The balloon is inflated and deflated several times,
squashing the atheromatous plaque. The inflation of the balloon
is visualized on the X-ray until there is no dent in the balloon.
The balloon is usually kept inflated for 1 to 2 minutes depending
on the individual.
Complications and risks associated with this procedure are
low but they do include:
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severe bruising or bleeding into the groin area. |
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changes in heart rhythm. |
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allergic reaction to the dye. |
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a tear in the lining of the artery being unblocked.
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blood clot in the artery into which the catheter is
inserted. |
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myocardial infarction during inflation of the balloon
(the patient is usually given blood thinning agents
to reduce this risk).
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Coronary
artery stenting
A stent is a small tube made of wire mesh that may be used
as an alternative to – or in combination with – PTCA.
Stents act like scaffolding, holding the artery wall open and
keeping the plaque from obstructing the flow of blood.
Stents are primarily used for preventing reocclusion after
angioplasty, reducing the chance of reocclusion from 30% to
20%. [Kern et al, 1997;
Takeuchi and Himeno,
1998; Muller et al,
1990] This is particularly important in people with diabetes
who have a higher risk of reocclusion.
Intravascular ultrasound is used before stenting to visualise
the full 360-degree circumference of the vessel wall, allowing
measurement of the lumen dimensions.
 View
the following series as an animation
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Figure 2.
Stents are put in place by being tightly mounted,
collapsed, on the outside of an angioplasty balloon.
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Figure 3.
The blockage has usually been treated with one or more
angioplasty balloons before a stent is inserted. As
with angioplasty, the balloon – with the stent
surrounding it – is threaded along the ultra thin
guide wire to the blockage.
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Figure 4.
The balloon is expanded and as it expands the stent
expands to the same diameter and locks into place.
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Figure 5.
The balloon is then deflated and the balloon and wire
are removed.
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Figure 6.
Over time, the stent becomes a permanent structure with
cells growing around and through it.
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Complications of stenting are minimal but do occur. These
complications can increase morbidity and mortality and include
restenosis and thrombosis. In addition, rare stent complications
can occur when the vessel is damaged or there is incomplete
expansion of the stent.
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Coronary
artery bypass grafting (CABG)
CABG aims to reroute or bypass blood around an arterial
blockage using a blood vessel taken from another part of the
body. During the procedure, the patient is connected to a heart
and lung machine allowing the heart to be stopped by the administration
of specific drugs (cardioplegia) while the new vessel is grafted.
The preparation of the heart is carried out simultaneously to
the harvesting of the new vessel.
Until fairly recently the saphenous vein was always used,
with one end connected to the aorta and the other to the coronary
artery, below the blockage. However, it was then discovered
that the internal mammary artery (also known as the internal
thoracic artery) may also be used. It was also observed that
this vein stays open longer than the saphenous vein. Now surgeons
prefer to use this vessel whenever possible.
The indications for CABG include:
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disease of the left main coronary artery. |
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disease of all three major coronary arteries.
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abnormal function of the left ventricle.
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However, this procedure may also be indicated in other specific
circumstances and therefore every patient's situation should
be considered. CABG is usually recommended when it is thought
that no other procedure will give the same results. A calculation
of the risk/benefit ratio must be carried out by the physician.
Risks involved in CABG include bleeding, infection, stroke,
kidney failure and myocardial infarction.
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