This section covers the following specialised procedures which are only performed in large cardiac centres:-
1. Cardiac catheterisation
2. Coronary angioplasty
1. Cardiac catheterisation
(a) Purpose of the test
Despite the great value of the simple tests outlined in Section 1, it is
sometimes not possible to make important decisions about a patient’s
management without a catheter investigation. This is especially true in
patients with angina who are being assessed for possible surgery. The
purpose of the test is to obtain vital information about the blood pressure
within the heart, the function of the pumping chambers and valves, and the
exact severity and position of any narrowings in the coronary arteries.
(b) What it involves?
It is not possible to describe in detail every procedure because each
investigation is tailored to the needs of the individual patient. Catheter tests
can be done as an out-patient, usually, but patients are admitted for one or
two days. The test is performed on an empty stomach and a premedication
injection is given beforehand. The procedure takes place in a fully equipped
X-ray room and takes between twenty minutes and one hour.
The catheter is a long flexible plastic tube, about three feet long, and
roughly the diameter of the inside of a ball-point pen. It is inserted either
from the groin or the arm depending on local practice. The skin is “frozen”
with a local anaesthetic injection; after this the procedure is painless. The
catheter is inserted into an artery or vein using a needle puncture in the groin
or a small incision in the arm. The operator uses X-ray screening to help
him manipulate the catheter into the correct position within the heart.
Patients do not feel the catheter pushing around inside their chest, but they
may be aware of the occasional “missed beat”. Most patients are fascinated
to watch the procedure on the video screen. The ECG is checked
continuously and also the blood pressure at the tip of the catheter. X-ray films are taken by injecting a fluid down the catheter and
running a cine camera. Some injections cause a flushing hot sensation
which lasts a few seconds – patients will be warned to expect this. People
having coronary artery pictures taken occasionally experience angina – this
does not mean anything is going wrong, but you should inform the doctor.
When the test is over the catheter is removed. A few stitches are placed
in the arm, or simple pressure is applied for about ten minutes in the leg.
Some patients feel a bit “washed out” for a few hours after the test. The
nursing staff will check the groin or arm at intervals.
(c) Are there any risks?
The first doctor to perform a catheter did it on himself. Since then
many hundreds of thousands have been done and problems are rare. The
most common complication is for a bruise to form in the groin or for the
pulse in the arm to become weaker. These unusual events are not serious,
but may be inconvenient for a few days.
Serious complications are very rare but it would be wrong to give the
impression that investigations such as this can be performed on patients,
who may have serious heart disease, at zero risk. The chances of the test
causing a heart attack (which could be fatal) are about one in six hundred
cases. Your doctor will, therefore, not recommend a catheter test unless he
feels that the benefit of catheterisation outweighs this very small risk.
Patients must discuss any worries they may have with a doctor before the
test.t
(d) Catheter tests in children
Cardiac catheterisation can be performed in children and even in
newborn babies. Some degree of sedation or a general anaesthetic may be
required. Catheters with expandable balloons on them are sometimes used
to stretch narrowed valves in children.
2. Coronary angioplasty
Coronary angioplasty is an exciting new technique for treating
coronary disease. The first procedure was done in 1977 and development
has been rapid since then. Patients with angina usually have narrowings or
blockages in one or more of the three main coronary arteries. (See HIS
Chapter 4: What is angina?). The idea of coronary angioplasty is to pass
a very fine catheter down the coronary artery and across the narrowed or blocked section. A sausage shaped balloon, mounted on the end of the
catheter, is then inflated which stretches the vessel and squeezes and disrupts
the material blocking it. When the balloon is deflated and removed an
muscle.
demanding – the balloon when inflated is no more than 3 mm. in diameter.
Although it sounds simple, yet angioplasty is technically
The main advantages of coronary angioplasty are avoidance of major
heart surgery, reduced hospital stay (two or three days) and rapid return to
normal life. From the patient’s point of view the procedure is very similar to
cardiac catheterisation. (See page 207.) though it may take much longer to
manipulate the balloon catheter into the right spot. Angina attacks during
cases when the
balloon is deflated.
At the moment only about one fifth of the patients having a catheter
test for angina are suitable for angioplasty. The technique can also be used
in patients with previous bypass graft surgery in whom the graft has become
narrowed.
Complications
Most angioplasty procedures are uncomplicated. Sometimes, however,
the treatment completely blocks off the artery which was previously only
narrowed. If this happens and the doctor thinks that serious injury to the
heart will result, he may ask a surgeon to perform an immediate bypass graft
operation. Patients undergoing angioplasty must, therefore, understand that
they may end up having an urgent operation and be prepared for this. The
chances of urgent surgery being needed are no more than one in 25 cases and
the results of such surgery are good.
In a few cases the angioplasty is a technical failure but no damage is
done. These patients are usually referred for surgery, but it is not necessary
to do this immediately.
Here are a few facts and figures about coronary angioplasty.
1. About one fifth of the patients investigated by catheter for
angina are suitable for angioplasty. As the technique
develops more patients will be suitable.
2. The procedure is successful in nine out of ten patients.
3.Angina pain recurs within six months in about one in six
patients. A repeat procedure is usually successful.
4.We do not know how long a successful result can last.
Some patients treated seven years ago are still free of pain.
5.It is usual for doctors to prescribe some tablets in the early
months following angioplasty.