See also AEROBIC CAPACITY; AEROBIC EXERCISE;
AGING, CARDIOVASCULAR CHANGES THAT OCCUR WITH;
PHYSICAL EXERCISE AND CARDIOVASCULAR HEALTH.
cardiac catheterization A diagnostic or thera-
peutic procedure in which the cardiologist inserts
a long, flexible, thin tube into an ARTERYnear the
surface of the SKINand threads it through the
artery into the HEARTor theCORONARY ARTERIES. The
cardiologist uses FLUOROSCOPY (moving X-RAY) to
view the progress of the catheter’s insertion via
closed-circuit television. During cardiac catheteri-
zation the cardiologist typically injects dye into the
coronary arteries to visualize the flow of BLOOD
through them (cardiac ANGIOGRAM).
Reasons for Doing This Test
Cardiac catheterization helps diagnose CORONARY
ARTERY DISEASE(CAD) and the extent of coronary
artery occlusion (blockage). The cardiologist also
may use cardiac catheterization to diagnose dam-
aged or dysfunctional heart valves and biopsy the
endomyocardium (inner lining and MYOCARDIUMof
the heart). Therapeutic applications of cardiac
catheterization include ATHERECTOMYand percuta-
neous transluminal coronary angioplasty (PCTA),
also called balloon ANGIOPLASTY. In PCTA the cardi-
ologist inflates a tiny balloon at the catheter’s tip
to compress ATHEROSCLEROTIC PLAQUEthat is occlud-
ing a coronary artery.
Preparation, Procedure, and RecoveryCardiac catheterization requires little preparation
beyond nothing to eat or drink for six to eight
hours before the scheduled procedure. The
catheterization takes place in a sterile setting.
Because there is a slight risk for complications that
would require immediate OPEN HEART SURGERY, the
catheterization facility has full operating room and
surgical team capacity. At the start of the proce-
dure the cardiologist administers a general seda-
tive to help the person relax, and injects a local
anesthetic into the tissues around the area where
the catheter will enter the artery. The cardiologist
makes a tiny incision to gain entrance to the
artery, and threads the catheter through the artery
to the heart and coronary arteries. Typically the
cardiologist videotapes the catheterization for fur-
ther study or review following the procedure.
Depending on the reason for the catheteriza-
tion and the cardiologist’s findings, the procedure
takes 45 to 90 minutes. When finished, the cardi-
ologist withdraws the catheter, sutures the inser-
tion incision, and places a pressure dressing over
the wound. The person remains lying down for six
to eight hours, in a recovery area, allowing a good
clot formation to develop and also permitting the
sedative to wear off. Most people are able to go
home the same day, though must have a friend or
relative do the driving, and can return to regular
activities within a week.Risks and Complications
The most significant, though an uncommon, risk
of cardiac catheterization is HEART ATTACKor STROKE
from atherosclerotic plaque the catheter dislodges.
Some people may have a HYPERSENSITIVITY REACTION
or allergic response to the injected dye with
angiogram. Also uncommon—though possible—is
that the cardiologist may discover, upon reaching
the occlusion, that the atheroma (plaque forma-
tion) is unstable and may determine that immedi-
ate CORONARY ARTERY BYPASS GRAFT(CABG) will be
necessary. More common complications include
bleeding and discomfort at the insertion site or
INFECTIONafter the procedure. For most people,
cardiac catheterization is uneventful and provides
the information the cardiologist needs to make a
definitive diagnosis.
See also STENT; SURGERY BENEFIT AND RISK ASSESS-
MENT; VALVULAR HEART DISEASE.cardiac cycle The complete sequence of the
heart’s contractions that results in ejecting BLOOD
from the HEARTto the LUNGSand body. Each car-
diac cycle represents two paired actions that begin
when the SINOATRIAL(SA) NODE, a cluster of special-
ized NERVEcells located at the apex of the right
atrium, emits an electrical pacing impulse. The
impulse causes the right and left atria to contract
simultaneously, sending blood to the respective
ventricles. The right atrium sends to the right ven-
tricle deoxygenated blood returning to the heart
from the body; the left atrium sends to the left
ventricle oxygenated blood returning to the heart
from the lungs.
The ATRIOVENTRICULAR(AV) NODE, a second clus-
ter of specialized nerve cells located at the base of28 The Cardiovascular System