Answered by: Dr OP Yadava | CEO & Chief Cardiac Surgeon, Show
Q: I am a 41 years old man and I underwent a routine ECG and the report showed sinus rhythm, left axis, non-specific ST-T abnormality (elevated). Otherwise it was a normal ECG. What does it mean? A:ST segment and T wave are ECG terminologies and these are arbitrary names
given to certain segments of the tracings of the ECG. ST-T wave changes can occur in a number of situations, which are well defined. However some times these changes occur for conditions, which are either ill defined or even they may be compatible with total normalcy and therefore, these changes are called non-specific ST-T wave changes. These could occur, as I told earlier, as a minor variation of normalcy. They could also appear because of electrolyte imbalances, because of any inflammation of
the covering layer of the heart and so and so forth. Non-specific ST-T wave changes call for no treatment. At best, may be one can report any symptoms that an individual has to his doctor and get a repeat ECG done after six months to one year to compare the changes. But by far and large, these changes are benign and have no ill connotation. 
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T wave anomalies are incompletely understood and associated with a broad differential diagnosis. A T wave abnormality can be associated with a life-threatening disease or be a clue to a mysterious illness. T wave abnormalities may also be benign and may be commonly seen in at least half the leads in a 12-lead ECG. While the T wave is challenging to interpret, it remains a fundamental part of ECG interpretation. What Is the T Wave in Electrocardiography?The T wave on the ECG is the positive deflection after the QRS complex. It represents the repolarization of the ventricular myocardium. To understand the T wave, let’s first briefly go over depolarization and repolarization. Both of these processes represent a shift in the electrical potential and ions of the cells. This is accomplished mainly by sodium, potassium, and calcium ions. At baseline, the outside of these cells are positive in relation to the inside of the cells. As depolarization begins the positive ions flood the cells making the inside positive. Repolarization is the resetting of the ions, restoring the inside to negative and the outside to positive. Both depolarization and repolarization occur from the epicardium to the endocardium (outside of the heart to the inside of the heart)
If you’d like to learn more about this entire process, sign up for one of our EKG interpretation video courses for an in-depth explanation. On the ECG, depolarization is represented by the QRS complexes, and the T waves represent repolarization. Depolarization is when the ventricles contract and pump blood, and repolarization is when the ventricles relax and fill with blood. Let’s look at this process in picture form and then show what the ECG machine sees. Here is a piece of cardiac tissue. The endocardium is to the left, and the epicardium is to the right. During the tissue’s resting state, the outside of the tissue is positive, while the inside is negative. During depolarization, the inside of the tissue becomes positive from left to right. The ECG sees this impulse going toward the electrode and gives a positive or upright deflection. There is then a slight pause in the ion transfer process displayed on the ECG as a flat line (ST segment). This is followed by repolarization (resetting of the ions). Since this process also occurs from the endocardium to epicardium (left to right), the T waves will be in the same direction as the QRS complexes, that is, upright. What Does a Normal T Wave Look Like?Normal T waves are typically upright and generally follow the same direction as the QRS complexes. Hence T waves are upright (positive deflection) in leads 1, 2, aVL, aVF, and V2 through V6. The T waves are typically downward (negative deflection) in aVR. In leads 3, and V1, the T wave direction is variable. Normal T waves are slightly asymmetrical in shape, with a rounded peak that occurs closer to its end than its beginning. The asymmetry is due to a steeper downslope than the upslope of the wave. The amplitude of the T wave should not exceed 5 mm in limb leads and more than 10 mm in precordial leads, with the amplitude highest in V2-V3 leads. Amplitude diminishes with increasing age. Negative T waves, also known as T wave inversions, from V1 to V4 leads are frequently found in children and are normal. T wave inversion is less commonly found in healthy adults but can occur from V1 to V3. The depth of the T wave also becomes progressively shallow from one to the next lead.
Start Your Membership TodayWe make electrocardiogram interpretation simple and understandable. The videos are interactive, and have detailed, easy to follow illustrations. Understanding Abnormal T-WavesECG interpretation must be in the context of the individual patient. The T wave is enigmatic, and a holistic interpretation strategy is essential to discern normal from abnormal. Inverted T WavesT wave inversions can result from life-threatening events such as acute coronary ischemia, pulmonary embolism, and CNS injury. They can also be completely benign, as in persistent juvenile T-wave inversion and normal variant T-wave inversions. Commonly T wave inversions are grouped into primary and secondary T wave changes. For simplicity, a primary change is due to a primary problem in the repolarization of the cardiac tissue. Primary changes describe alterations in the duration or morphology of the spike without simultaneous changes in the orderly activation sequence. Primary T-wave changes can be benign, such as persistent juvenile T-wave patterns, or serious such as from acute coronary ischemic events, abnormal electrolytes effects, or drug effects. A secondary change means that the abnormality in repolarization is due to something else, such as an abnormality in depolarization. A good example is the ST and T wave changes that occur in a bundle branch block. An inverted T wave is considered abnormal if the inversion is deeper than 1.0 mm. Inverted T waves found in leads other than the V1 to V4 leads are associated with increased cardiac deaths. Inverted T waves are seen in the following conditions:
Clues to telling primary from secondary T wave changesT-wave to QRS axisCalculating the QRS and T wave axes will help you distinguish primary from secondary T wave changes. With primary T wave changes, the T wave axis is similar to the QRS axis. With secondary changes, the T wave axis is usually opposite to the QRS axis. Another way to look at this is that with primary T wave changes, the T waves follow the same direction as the QRS complexes, with the exception of the abnormal T waves. The abnormal T waves are isolated. With secondary T wave changes, all of the T waves are opposite in direction to the QRS complexes. For example, everywhere the QRS complexes are upright, the T waves are inverted, and everywhere that the QRS complexes are downward, the T waves are upright. T-wave morphologyPrimary T wave changes typically involve the T wave alone, and the T waves appear symmetrical. Secondary T wave changes usually also involve the ST segments, and the T wave changes are asymmetrical.
Start Your Membership TodayWe make electrocardiogram interpretation simple and understandable. The videos are interactive, and have detailed, easy to follow illustrations. Biphasic T WavesBiphasic, also known as diphasic T waves, have positive and negative deflections. In other words, two waves are present in opposite directions. There are two leading causes of biphasic T waves, each with a different biphasic pattern.
Flattened T WavesWhile Flattened T waves are non-specific, they may be seen in patients with myocardial ischemia. A flattened T wave can be completely flat or vary in height from -1.0 mm to + 1.0 mm. Flattened T waves can be caused by the following:
The typically small-size U wave becomes more prominent in hypokalemia and digitalis therapy. As hypokalemia worsens, the T wave becomes increasingly flattened while the U wave increases in prominence. In digitalis toxicity, the QT interval shortened and sagged before the flattered T wave and prominent U wave. Hyperacute T WavesHyperacute T waves have an amplitude higher than 10mm in the chest leads and above 5mm in the limb leads. They are broad-based with a peaked, symmetric morphology. After QT protraction, hyperacute T waves are the earliest ECG sign of acute ischemia. Hyperacute T waves are most evident in the anterior chest leads and are seen soon after coronary infarction. They tend to be short-lived. Causes of the hyperacute T waves include acute myocardial infarction, hyperkalemia, and acute myopericarditis.
Start Your Membership TodayWe make electrocardiogram interpretation simple and understandable. The videos are interactive, and have detailed, easy to follow illustrations. Camel Hump T WavesAs the name suggests, camel hump T waves exhibit double peaks. Originally associated with hypothermia, these waves are now deemed non-specific. Because they arise from several different events, they are challenging to interpret. Dramatic ECG changes of camel hump T waves have been observed in multiple electrolyte imbalances. For example, elevated U waves at the end of the T wave occur in severe hypokalemia. P waves are embedded in the T wave in various types of heart block and tachycardia. Importance of Interpreting the T Waves CorrectlyT waves are associated with a wide range of diagnoses. Changes in the T wave may represent several pathologies, including cardiac disease, pulmonary disease, neurogenic causes, and multiple electrolyte imbalances. However, T wave changes may also be a normal variant. Interpreting abnormalities in the T wave without clinical history, physical examination, and laboratory studies is a common mistake. T wave abnormalities are non-specific in the absence of symptoms and clinical history. Therefore, a comprehensive understanding of the T wave is critical for accurate diagnosis and optimal patient care. Learn To Master The Art Of ECG InterpretationLearning to interpret ECGs is a crucial skill for healthcare providers to master. At Executive Electrocardiogram Education, we make electrocardiogram interpretation simple and understandable. Our self-paced video courses give a one-on-one feel to learning to interpret ECGs. If you’d like to try out one of our courses absolutely free, you can try our ACLS rhythms course. It’s perfect for anyone looking for a basic overview of ECG interpretation or if you’d just like to get a feel for how our online ECG classes work. You can also get access to all of our non-CME courses at once by signing up for our ECG Premium course. Don’t hesitate to email us if you have any questions about our courses, prices, or even institutional subscriptions.
Download Our EKG Interpretation Cheat Sheet Don't miss your chance to get our ultimate EKG interpretation cheat sheet absolutely free! We Have An Offer Before You Go!Save 25% On A One Year Subscription To Any Of Our Courses Save 25% At Checkout With Coupon ECGEDUANNUAL Or Click The Link Below And It Will Be Auto-Applied No thanks, I’m not interested! A Must For Anyone Studying ACLSSign Up For Our FREE ACLS Rhythms Course Don't miss your chance to sign up for our free course with interactive quizzes and detailed rhythm descriptions. No thanks, I’m not interested! How serious is T wave abnormality?T-wave abnormalities are common electrocardiographic occurrences in patients with non-ST-segment elevation acute coronary syndromes. Although these abnormalities are considered relatively benign, physicians use them to guide therapies.
Is nonspecific T wave abnormality normal?ST- and T-wave changes may represent cardiac pathology or be a normal variant. Interpretation of the findings, therefore, depends on the clinical context and presence of similar findings on prior electrocardiograms. Nonspecific ST-T-wave changes are very common and may be seen in any lead of the electrocardiogram.
What does nonspecific T abnormality mean?Hyperventilation: Finally, hyperventilation can cause deep, reversible ST segment abnormalities. T wave inversions and T wave flattening are sometimes present for no clear clinical reason, hence are referred to as “non-specific T wave abnormalities.”
What causes T wave abnormality?Primary T-wave abnormalities (ischemia or injury) are due to alterations in myocardial cellular electrophysiology and secondary T-wave abnormalities (bundle branch block or ventricular Hypertrophy) are subsequent to alterations of sequence of ventricular activation.
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Nonspecific t wave abnormality is it dangerous
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