Angioplasty (Coronary Balloon)

THE FIRST SUCCESSFUL CORONARY ANGIOPLASTY
was performed by the late Dr. Andreas Gruntzig in Zurich,
Switzerland, in 1977. Dr. Gruntzig pioneered the modern
era of interventional cardiology with his innovative
percutaneous transluminal coronary angioplasty (PTCA).
Using a double-lumen balloon catheter, he performed the
first PTCA by dilating the proximal left anterior
descending coronary artery and unblocking an atheromatous
obstruction of a 37-year-old man with angina. Repeat
angiograms on the 10th anniversary of this procedure
showed continued vessel patency; the patient has remained
symptom-free for more than 20 years.

I. PROCEDURE
PTCA, percutaneous transluminal coronary angioplasty,
is so named because the instrument is passed through the
skin (percutaneously) and then through the lumen of the
artery (transluminal) into the coronary artery, which is
molded into shape (angioplasty). The balloon-tipped
catheter is positioned next to the plaque of atheroma in
the artery (see Figure 1 in chapter entitled ‘‘Angina.’’).
The balloon is inflated for 30–60 seconds and then
widened by pressure (see Fig. 1). The narrowed artery
becomes dilated due to splitting (dissection) of the plaque
and overstretching of the middle wall (media) of the artery.
Transient chest pain may occur during the inflation but is
quickly relieved. Several inflations may be necessary to
accomplish dilation of the artery. The balloon is then
deflated, and dye is injected so that the cardiologist can see
if adequate dilation and flow of blood has been achieved.
An optimal angiographic result (less than 20% residual
stenosis), is obtained in less than 25% of patients after
PTCA) is associated with a favorable late clinical outcome.
Following angioplasty, the patient is monitored in the
coronary care unit for about 24 h.
PTCA expands the coronary lumen by stretching and
tearing the atherosclerotic plaque and vessel wall and to a
lesser extent, by redistributing atherosclerotic plaque
along its longitudinal axis. There is no evidence that the
balloon compresses atheromatous plaques. PTCA has
been transformed in the past decade with the development
of angioplasty to assist with lesions exhibiting complex
characteristics. The term percutaneous coronary intervention
(PCI), is now used to include angioplasty with or
without stent deployment. More than 700,000 patients in
the United States had PCIs in 2004, far exceeding the
number of patients who had coronary artery bypass graft
(CABG) surgery. This method of treating coronary heart
disease (CHD) is available in most major medical centers
worldwide.
Atherosclerosis, however, usually affects several segments
of the coronary arteries. As the disease advances, every
effort must be made to halt its progress. All risk factors —
smoking, high blood pressure, stress, cholesterol higher
than 200 mg (5.2 mmol), and LDL cholesterol higher than
100 mg/dl (2.5 mmol) — must be controlled. Diet plus
drug therapy is usually necessary to achieve this goal (see
chapter entitled ‘‘Dyslipidemia.’’)

II. INDICATIONS
A. Stable Angina
Patients with bothersome stable angina who do not achieve
sufficient relief with medical therapy are candidates for
coronary angioplasty, if they have any of the following:
1. One coronary artery obstructed (greater than 75%) by a
discrete, preferably noncalcified atheromatous plaque
without complex angiographic characteristics. Patients
with symptoms and obstruction of the left anterior
descending artery or right coronary artery before the
artery gives off the first branch are the most ideal
candidates. Procedural success rate exceeds 97% with
these candidates and is associated with a low risk of
early complications.
2. A broad range of obstructive lesions including obstructions
in two and three arteries. This is now possible
with increased experience and new steerable catheter
systems. Success is less likely to occur in patients with
obstruction in the circumflex artery or at lower points
(distal) in the coronary arteries where there are irregular
bends or turns.

B. Acute Heart Attacks
Patients with acute heart attacks may have the clot
dissolved by drugs such as streptokinase or tissue-type
plasminogen activator (t-PA); or they may undergo
coronary angioplasty to dilate the obstructed artery and
insertion of a stent. Often coronary angioplasty with stent
implantation is performed without the use of thrombolytic
agents. Several randomized clinical trials indicate that this
aggressive interventional technique is superior to the use of
thrombolytic agents, and it is advocated in centers that
have facilities for rapid angiography and trained personnel
for PCI (see the chapter Heart Attacks).

C. Unstable Angina and Non-ST Elevation
Myocardial Infarction
1. Clinical Study — RITA 3 Investigators
Question posed: We will test the hypothesis that PCI is
better than a conservative strategy in patients with unstable
angina or non-ST elevation myocardial infarction.
Methods: A randomized multicenter trial of 1810
patients with acute coronary syndromes was used. Patients
were assigned an early PCI or conservative strategy. The
antithrombin agent in both groups was low molecular
weight heparin, enoxaparin. Primary end points were a
combined rate of death, nonfatal infarction, or refractory
angina at four months and a combined rate of death or
non fatal infarction at one year.
Results: At 4 months 86 (9.6%) of 895 patients in the
PCI group had died or had a myocardial infarction or
refractory angina versus 133 (14.5%) of 915 patients in the
conservative group, p¼0.001. This difference was mainly
due to a halving of refractory angina in the intervention
group. Death or infarction was similar in both groups at
one year when symptoms of angina were improved with
antianginal medications and significantly reduced with
the interventional strategy ( p¼0.0001). The procedural
success rate after PTCA was approximately 80% 20 years
ago compared with approximately 97% in recent years,
including success in women.

OUTCOME OF ANGIOPLASTY
Successful reopening of the artery is achieved in greater
than 90% of cases, and with better blood flow, angina
improves. The majority of patients return to work a few
days later and have no recurrence of the angina for at least
six months. Early complications are most often the result
of abrupt vessel closure, defined as sudden occlusion of
the target vessel during or shortly after PCI. This occurs
in less than 2% of patients. The pathophysiology involves
local vessel dissection with obstructive resection flaps
accompanied by thrombus formation. This process usually
leads to myocardial infarction and need for bail-out stent
or bypass surgery. The recent use of platelet IIb/IIIa
receptor blockers and stenting has reduced the incidence of
adverse outcomes of acute vessel closure.
Death occurs in less than 1% of cases. A heart attack
occurs in less than 2% of cases, because the crushing and
splitting of the plaque of atheroma exposes cells and
substances that promote blood clotting. Thus clopidogrel,
aspirin, or platelet receptor blockers are useful additions
to the drug armamentarium to assist with successful
PCI. In about 20% of patients, it is not possible to pass
the catheter through the narrowed area. In about 10%, the
dilation cannot be accomplished because the plaques are
calcified and rock-hard. These complications are similar to
those of CABG surgery.
The main limitation of PTCA is narrowing of the
artery (restenosis) at the site of angioplasty. This occurs
in approximately 33% of cases within 6 months of the
procedure. In these patients chest pain returns. This figure
has not changed much over the past 20 years. Despite
intensive research to prevent restenosis, the problem has
not been overcome.
The pathogenesis of restenosis in response to mechanical
injury induced by balloon angioplasty is incompletely
understood and is multifactorial. Several, pharmacologic
agents have been tested in randomized controlled
trials including aspirin, other antiplatelet agents, anticoagulants,
antiproliferative agents, calcium antagonists,
and folic acid. Only stent implantation has been shown to
significantly decrease restenosis rates to approximately
25% at 6 months (see the chapter Stents). In the stent
restenosis study (STRESS), restenosis rates were 32 and
42% percent in the stent and PTCA groups, respectively.
Fortunately, these stenoses can be dilated more easily
on the second procedure with relief of symptoms in
many, but CABG is still frequently required in subsequent
years. Additionally, the need for repeat revascularization
tapers off rapidly after the second year. Still,
restenosis may be clinically silent in more than 30% of
patients.
Coronary angioplasty does not compete with CABG
surgery. Approximately 25% of individuals cannot have
coronary angioplasty or stents and must have CABG.
Coronary angioplasty is much cheaper. The hospital stay is
only one day, and patients can usually return to work
within a few days. Of those who undergo angioplasty,
approximately 85% are angina-free and able to be more
active. Most important, the procedure is done in patients
with stable or unstable angina mainly to relieve recurrent
chest pain of angina. It has not been shown in randomized
clinical trials to prolong life significantly or reduce the
occurrence of myocardial infarction.

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