Heart Anatomy

The Heart Is a Pump

The heart is a muscle that pumps blood
around the body through a series of
pipes. These pipes are called arteries.
The left side of the heart receives fresh,
oxygen-rich blood from the lungs and
then pumps it out a large artery called
the aorta that branches into smaller
arteries that go to all parts of the body.

The various parts of the body then take

the oxygen out of the blood and the now
stale, oxygen-poor blood is returned to
the right side of the heart through pipes
called veins. The right side of the heart
pumps this stale blood to the lungs
where it picks up more oxygen and the
cycle begins again.

The Coronary Arteries

The heart muscle, like every other part of the body, needs its own oxygen-rich blood
supply. Arteries branch off the aorta and spread over the outside surface of the heart.
The Right Coronary Artery (RCA) supplies the bottom part of the heart. The short Left
Main (LM) artery branches into the Left Anterior Descending (LAD) artery that supplies
the front of the heart and the Circumflex (Cx) artery that supplies the back of the heart.

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Heart Disease
Heart disease, also known as cardiovascular disease, is a general term for a variety of
conditions that affect the heart and blood vessels. It is a chronic disease that can lead to
serious events including heart attack and death. Heart disease is one of the leading
causes of death in Canada and worldwide. The most common form of heart disease is
coronary artery disease (CAD) caused by atherosclerosis.

Atherosclerosis
Over time, plaque builds up on the inside wall of arteries. Plaque is made of several
substances including cholesterol. This build up is called atherosclerosis or hardening of
the arteries. It can start at an early age and is caused by a combination of genetic and
lifestyle factors that are called risk factors. Atherosclerosis can cause a narrowing in the
arteries to various parts of the body such that blood flow is slowed or blocked. Poor
blood flow to the brain can cause a stroke. Poor blood flow to the arms or legs is called
peripheral artery disease (PAD). Poor blood flow to the heart is called coronary artery
disease (CAD) and can cause angina or a heart attack.

Angina
Plaque build up in the coronary arteries to the heart causes poor blood flow and the
heart may not receive all the oxygen that it needs. This usually occurs when the heart
has to work harder such as while walking, climbing stairs, or feeling worried or upset.
When the heart isn’t getting enough oxygen, it can cause pain or pressure in the middle
of the chest that may spread to the arms, neck, or jaw. Sometimes there may be
shortness of breath, sweating, or nausea. This pain is called angina and usually goes
away within 2 to 20 minutes by resting or taking a medication called nitroglycerin. It
does not cause any heart damage.

Unstable Angina
Sometimes, the plaque in the artery can crack open suddenly. The blood forms a clot
over the cracked plaque but this clot causes a sudden narrowing of the artery. The
chest pain or angina may now occur more frequently, with less exercise, or last longer
than usual. This change in the pattern of angina is called unstable angina.

Heart Attack
If the heart is starving for blood and not getting enough oxygen for more than 20
minutes, then a part of the heart muscle dies causing some permanent damage. This is
called a heart attack or myocardial infarction (MI). Heart attacks are confirmed with

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blood tests and a test that shows the electrical activity of the heart called an
electrocardiogram (ECG).

Some heart attacks involve only a small area of the heart and can be managed with
standard medical treatment in hospital. Some heart attacks involve a larger area of the
heart and have a specific pattern on ECG. These heart attacks are called ST-elevation
myocardial infarctions (STEMI) and require immediate treatment with clot dissolving
drugs or opening up the artery with balloon angioplasty and stents.

Chest Pain Angina Unstable Heart Attack

Angina
While Resting Rare Sometimes Common
Goes Away with Rest or Nitroglycerin Yes Yes Sometimes
Lasts More than 20 Minutes No No Yes
Causes Permanent Heart Damage No No Yes

Heart Damage
Some heart attacks cause very little damage to the heart muscle and the heart can still
pump strongly. Some heart attacks are larger and the muscle damage causes a weak
heart. There are several heart tests that measure the strength of the heart such as an
echocardiogram (an ultrasound of the heart that looks at the pumping strength of the
heart and how the heart valves work), nuclear scans such as a MUGA scan, or a
ventriculogram which is commonly done during an angiogram.

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Tests
There are several tests that can check if plaques are blocking the coronary arteries to
the heart. These include: treadmill test (fast walking on a treadmill while attached to an
ECG machine), nuclear scan such as SPECT or PET scan, stress echocardiogram, CT
angiography scan, or angiogram.

Angiogram
With this test, a small tube or catheter is inserted into an artery in the groin or wrist and
guided to the heart. A dye is injected through this tube and into the coronary arteries so
that they can be seen by an X-ray. This shows if there is plaque blocking the arteries
and whether the blockages should be treated just with medications or if there is also
need for an angioplasty or coronary artery bypass grafting (CABG) surgery. Sometimes
dye is injected into the pumping chamber of the heart to check how strong the heart is
and if there was any damage to the heart muscle. This is called a ventriculogram. The
catheter is then removed.

Insertion Sites for Angiogram

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Angioplasty and Stents
Sometimes blockages in the coronary arteries can be fixed with angioplasty. A small
tube or catheter is inserted into an artery in the groin or wrist and guided to the heart as
with the angiogram. In this procedure, a small balloon at the end of the catheter can be
inflated for a short period of time to push the plaque back against the wall of the artery
so that blood can flow better.

In many patients, a small metal mesh tube or stent, is placed over the balloon. When
the balloon is deflated and removed, this stent stays permanently where the blockage
was and lowers the risk of this area narrowing again. Some stents are metal alone (bare
metal stents). Others have a medication coating on them (drug eluting stents).

A. The balloon catheter and collapsed stent are inserted into the narrowed artery.
B. The balloon is inflated to expand the stent. C. The balloon catheter is removed leaving
the stent in place.

Advantages of Angioplasty
Over 90% of angioplasties are successful immediately. Blood flow through the artery
returns to normal or near normal. Some people may not have complete relief, but their
symptoms are improved, allowing them to be more active and comfortable.

There is no incision as this is not surgery and you are not put to sleep (general
anesthesia). Most people are up and walking on the same day. Some people go home
the same day, but some patients are required to stay overnight and go home the
following morning.

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Disadvantages of Angioplasty
An artery may become narrow again after angioplasty. This is called restenosis. If the
artery narrows enough, you may feel angina again. The use of stents has reduced the
restenosis rate. Restenosis is usually treated with a second angioplasty, but
occasionally bypass surgery is needed or medical therapy is used.

Risks of Angiogram and Angioplasty

Angiogram and angioplasty (with or without stent implantation) are common procedures.
Your physician has carefully considered your clinical condition and believes that the
benefits of the procedure outweigh the risks. However, since these procedures are
invasive there are risks associated with them.

Common risks include:

• Bleeding at the catheter insertion site or other organs due to blood thinning
medication (anticoagulants)

Less common but potentially more serious risks include:

• Heart attack

• Stroke

• Unknown dye allergy

• Kidney problems, including kidney failure requiring dialysis

• Emergency heart surgery

• Death

• Other rare and unpredictable complications

In 1% to 2% of angioplasty cases, the artery collapses or is damaged by the wire or

balloon. A stent can often fix this, but sometimes patients need emergency coronary
artery bypass surgery. At the Heart Institute, our operating rooms are close by if a
patient needs surgery.

Discuss the risks and benefits of your procedure with your doctor.