Cardiac catheterization and angiograms are medical procedures that allow doctors to examine the inside of the heart and arteries. However, there are some differences between the two.

Cardiac catheterization involves a doctor inserting a long, thin tube into an artery and guiding it to the heart.

Healthcare professionals may also take an angiogram during cardiac catheterization, using contrast dye and imaging tests. Alternatively, they may inject the dye and take a CT scan without cardiac catheterization.

This article discusses the difference between cardiac catheterization and an angiogram, who may need them, what to expect during and after each procedure, and possible complications.

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Cardiac catheterization and an angiogram are medical procedures in which a doctor can examine the heart. In fact, a doctor may follow cardiac catheterization with an angiogram. However, there are several differences between the procedures.

Cardiac catheterization

A doctor typically uses cardiac catheterization to diagnose and treat various heart conditions. The procedure involves inserting a thin, long, flexible tube known as a catheter into a blood vessel and guiding it close to the heart.

A healthcare professional can then measure blood pressure in the heart, look for any blockages, and take samples of blood or heart muscle.

They may also use cardiac catheterization to replace heart valves or repair heart abnormalities.


A healthcare professional typically uses an angiogram to examine the arteries and the heart. The procedure may involve inserting a catheter into an artery before injecting a special dye and taking imaging scans, such as an X-ray. They may refer to this as an invasive angiography.

Alternatively, a doctor may inject the dye into a blood vessel without performing cardiac catheterization. They will then use a CT scan to take images. Healthcare professionals may refer to this method as a coronary CT angiography.

The images will allow a doctor to assess how the dye and, therefore, the blood flows through the arteries. The dye will highlight any blockages, narrowing, or other irregularities.

A doctor will typically use left cardiac catheterization and an angiogram to determine if there are any blockages or damage in the arteries. They can also help a doctor gain a clearer understanding of results from previous tests such as a heart MRI or CT scan.

A healthcare professional may use right cardiac catheterization to measure blood pressure in the heart and sometimes to take biopsies.

Cardiac catheterization

There are several reasons a person may require cardiac catheterization, including:

  • measuring blood pressure and levels of oxygen inside the heart and arteries
  • diagnosing heart conditions such as heart disease, an irregular heartbeat, and heart valve disorders
  • treating heart abnormalities present from birth
  • replacing or widening heart valves
  • collecting biopsies of tissue from the heart for further testing
  • allowing for further testing methods through the catheter, such as an angiogram, or angioplasty, which is a procedure to widen blood vessels
  • helping a doctor evaluate whether heart surgery is suitable for a person


A doctor may perform a left heart catheterization and angiogram to find and treat blockages in the coronary arteries.

If a person is having a heart attack, a doctor may use an angiogram to help determine treatment options.

Before a cardiac catheterization or angiogram, a person may need to undergo tests such as an electrocardiogram, exercise stress test, or echocardiogram.

A doctor may require a person to fast for several hours before cardiac catheterization or an angiogram.

Cardiac catheterization

To begin cardiac catheterization, a doctor may administer medication through an intravenous line in a person’s vein to help them relax.

A healthcare professional will typically administer local anesthetic to the area in which they will insert the catheter, such as the upper thigh, arm, or neck. This will numb the area and allow the doctor to make an incision.

They will then insert a catheter into the blood vessel using a guide wire and move it up to the heart, allowing them to perform the necessary examinations or procedures.


To perform an invasive coronary angiogram, a doctor will typically follow the same steps as cardiac catheterization.

Once the catheter is in place, a healthcare professional can inject contrast dye into the artery and take imaging scans such as X-ray, MRI, or CT scans.

To perform a coronary CT angiogram, they will inject the dye into a blood vessel and create images of the heart and blood vessels using a CT scan.

A doctor can then assess the images for any irregularities.

After cardiac catheterization and an angiogram, a doctor will remove the catheter, close the wound, and apply a dressing.

A person may need to stay in the hospital for a few hours or overnight for monitoring, if necessary.

Any invasive procedure carries some risk of complications. However, cardiac catheterization and angiography are common procedures that a cardiologist will only recommend if they feel the test’s benefits outweigh the risks.

Minor complications can include bruising and pain at the site of the wound.

Serious complications are rare but can occur. A person should call 911 immediately if they experience any severe symptoms, such as chest pain, shortness of breath, severe bleeding, or signs of stroke.

Cardiac catheterization

More serious complications can include:

  • bleeding at the wound site that does not stop with firm pressure
  • dizziness
  • swelling, pain, excess bruising, or yellow or green discharge at the wound site
  • chest pain
  • fever
  • shortness of breath
  • irregularly fast or slow heartbeat
  • numbness in the leg or arm that has the wound site
  • heart attack
  • stroke


Following an angiogram, a person may experience a rash, itchy skin, or hives due to an allergic reaction to the injection dye. They may also experience nausea and hot flashes.

More serious complications can include severe allergic reactions to the injection dye and damage to the kidneys from the dye, possibly leading to acute renal failure.

Additionally, more serious complications of invasive angiogram may include bleeding at the wound site that does not stop with firm pressure. Additionally, there could be blood clots, which may lead to a stroke or heart attack.

Anaphylaxis: Symptoms and what to do

Anaphylaxis is a severe allergic reaction that can be life threatening. The symptoms develop suddenly and include:

  • hives
  • swelling of the face or mouth
  • wheezing
  • fast, shallow breathing
  • a fast heart rate
  • clammy skin
  • anxiety or confusion
  • dizziness
  • vomiting
  • blue or white lips
  • fainting or loss of consciousness

If someone has these symptoms:

  1. Check whether they are carrying an epinephrine pen. If they are, follow the instructions on the side of the pen to use it.
  2. Dial 911 or the number of the nearest emergency department.
  3. Lay the person down from a standing position. If they have vomited, turn them onto their side.
  4. Stay with them until the emergency services arrive.

Some people may need more than one epinephrine injection. If the symptoms do not improve in 5–15 minutes, or they come back, use a second pen if the person has one.

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Cardiac catheterization and an angiogram are medical procedures that allow a doctor to examine the arteries in the heart.

Doctors use cardiac catheterization to measure blood pressure in the heart, take heart tissue biopsies, diagnose heart conditions, place stents, and treat valve problems.

An angiogram allows a doctor to take imaging scans of the inside of the heart and arteries to help examine how the blood flows and diagnose heart conditions.

Minor complications of both procedures can include bleeding under the skin, pain, and bruising at the wound site. Major complications can include excess bleeding, a heart attack, or a stroke. Individuals should call 911 immediately if they experience any major complications.