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Cardio- is a combining form used like a prefix meaning “heart.” It is used in many medical and scientific terms.

Cardio- comes from the Greek �첹����í��, meaning “heart.” In fact, the English word heart and the Greek �첹����í�� are related. Learn more at our entry for heart.

What are variants of cardio-?

When combined with words or word elements that begin with a vowel, cardio- becomes cardi-, as in cardiectomy.

You may recognize the combining form cardio- from the word cardiogram, which is a recording of the activity of the heart. A cardiogram is also known as an electrocardiogram (EKG), and is used to diagnose heart conditions.

We now know that cardio- means “heart.” The second part of the word, -gram, refers to “something written, recorded, or drawn.” So, a cardiogram has the literal sense of a “heart recording.”

You probably also recognize the word cardio as its own word, short for cardiovascular exercise, such as running. Cardiovascular means “of, relating to, or affecting the heart and blood vessels,” and combines cardio- and vascular. Cardio gets the heart rate up and the blood moving.

What are some words that use the combining form cardio-?

• cardioactive
• cardioarterial
• cardiocele
• cardiodynia
• cardiograph
• cardiohepatic
• cardiolith
• cardiolipin
• cardiomuscular
• cardiopathy
• cardionephric
• cardiotomy
• cardiotonic
• cardiorespiratory
• cardiospasm

Based on the meaning of cardio-, a cardiologist specializes in what part of the body?