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A T wave inversion is a reading on one small part of an electrocardiogram (EKG or ECG). The T wave segment of a typical EKG test is expected to form a positive peak or upward spike while an inversion will look like a valley. An inversion of the T wave may indicate problems such as a heart attack, but can also be caused by many non-threatening conditions. The meaning of the T wave inversion is determined by looking at the other segments of the EKG along with the patient’s overall medical history; sometimes additional tests are performed to supplement the information from the EKG.
An EKG printout displays a line with peaks and valleys that represent different electrical states experienced by the heart during the heartbeat cycle. The different stages of contraction and release cause predicable patterns in the line, and areas where the line differs from the expected pattern can sometimes indicate possible medical problems. The P wave shows the electrical discharge that causes the contraction of the atria while the QRS set of peaks shows the contraction of the ventricles. The T wave segment itself shows the cells of the ventricles resetting their charges in preparation for the next contraction.
Potentially dangerous conditions that can cause a T wave inversion include heart attack, lack of adequate blood supply to the heart muscle, ventricular hypertrophy, infection in the area of the heart, and blood clots in the lung. Many other conditions or circumstances can cause the same T wave inversion without significant impact on the health of the individual. Imbalanced electrolytes, anxiety attacks, hyperventilation, and medications like digitalis can all cause inverted T waves but generally don’t represent any long-term risk to the patient’s health.
If the patient’s medical history does not indicate a moderate to high risk of heart disease, a T wave inversion by itself will usually be set aside as an insignificant reading. One specific type of T wave inversion is called Wellen’s warning; it occurs after an event that causes the heart to be starved for blood. It signals the presence of a lesion in the left anterior descending artery. When an inversion is seen along with an abnormal reading in another part of the EKG pattern, such as an elevation in the line between the S and T peaks, further testing may be done even without much prior indication of risk. A stress test in conjunction with an echocardiogram is an example of an additional measurement that can help explain the meaning of a questionable EKG readout.