Tachycardia is a heart rate that's too fast. Tachycardia is often defined as a heart rate that's more than 100 beats per minute in adults.

target heart rate

The target heart rate is your ideal heart rate, or pulse, during physical activity. Your target heart rate is within 50 to 85 percent of the maximum heart rate, which is the highest heart rate you should have during exercise. Determine your maximum heart rate by subtracting your age from 220. You can monitor your heart rate periodically during exercise by checking your pulse are the wrists, the inside of your elbow, the side of your neck and the top of the foot. To get the most accurate reading, put your finger over your pulse and count the number of beats in 60 seconds.

tetralogy of fallot

Tetralogy of Fallot is a complex heart defect in which blood pumped to the body is lacking in oxygen, sometimes resulting in the skin taking a blue tone. There are four components to the condition involving various parts of the heart. People are born with this condition, or develop it soon after birth. Most children diagnosed with this condition have open-heart surgery before school age. Some infants with tetralogy of Fallot may need an operation to allow for increased circulation of oxygenated blood. Lifelong medical follow-up is needed.

therapeutic hypothermia

Therapeutic hypothermia is a medical treatment that intentionally lowers the body temperature to protect the body following a period of insufficient blood flow due to such events as a cardiac arrest, embolism or stroke. Studies have shown that therapeutic hypothermia can improve survival as well as neurological function.

thoracic aortic aneurysm

A thoracic aortic aneurysm is an abnormal bulging or ballooning of the portion of the aorta the passes through the chest.


Thrombolysis is the breaking up of a blood clot.


Thrombosis is the formation or presence of a blood clot inside a blood vessel or chamber of the heart.


Thrombus is a blood clot that forms inside a blood vessel or chamber of the heart.

tilt-table test

If you often feel faint or lightheaded, your doctor may use a tilt-table test to find out why. During the test, you lie on a table that is slowly tilted upward. The test measures how your blood pressure and heart rate respond to the force of gravity. A nurse or technician keeps track of your blood pressure and your heart rate (pulse) to see how they change during the test.

trans fat

When liquid vegetable oil undergoes a chemical process called hydrogenation to create a solid, trans fat is formed. Trans fat is sometimes used in processed foods to prolong shelf life and to give food a desirable taste and texture. Research suggests that consuming trans fat can raise LDL (bad) cholesterol and lower HDL (good) cholesterol.

tricuspid valve regurgitation

Tricuspid regurgitation is leakage of blood backwards through the tricuspid valve each time the right ventricle contracts.

tricuspid valve stenosis

Tricuspid stenosis is a narrowing of the tricuspid valve opening. Tricuspid stenosis restricts blood flow between the upper and lower part of the right side of the heart, or from the right atrium to the right ventricle.


Triglycerides are the chemical form in which most fat exists in food as well as in the body. They circulate in the blood plasma and, in association with cholesterol, form the plasma lipids. Triglycerides come from fats eaten in foods or made in the body from other energy sources like carbohydrates. Calories eaten that are not used immediately by tissues, are then converted to triglycerides and transported to fat cells to be stored and used by the body as an energy source between meals. Hormones regulate the release of triglycerides from fat tissue so they meet the body's needs for energy.

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