Flat or inverted T waves

Introduction T wave is low or inverted: T wave is a voltage change that reflects the recovery period of ventricular electrical activation. The height of the T wave is lowered (called low level), and further the direction of the T wave is downward (called inversion), which is the potential change caused by the repolarization of the ventricle on the electrocardiogram, also called the ventricular repolarization wave. Many elderly patients with coronary heart disease have a deafness, and they all know that T wave low level and inverted are the manifestations of coronary heart disease. However, there are many reasons for the changes in T wave morphology, and they are not all unique manifestations of heart disease. When judging the significance of T wave changes, it should be closely combined with the clinical, and can not make a diagnosis of coronary heart disease.

Cause

Caused by diseases such as coronary heart disease or myocardial ischemia.

an examination

Related inspection

Cardiovascular dynamic electrocardiogram (Holter monitoring) two-dimensional echocardiography

The t wave is one of the five bands of the electrocardiogram. The bioelectric current generated when the heart beats, and the potential change map recorded from a specific part of the body by an electrocardiograph. Judging according to the electrocardiogram.

Differential diagnosis

Coronary artery heart disease (CHD) is called coronary heart disease (gun xn bìng). It is the most common type of heart disease. It refers to myocardial dysfunction caused by coronary artery stenosis and insufficient blood supply and/or Organic disease, it is also known as ischemic cardiomyopathy (IHD). CHD is the result of a variety of coronary artery disease, but coronary atherosclerosis accounts for the vast majority (95%-99%) of coronary heart disease. Therefore, it is customary to consider coronary heart disease as a synonym for coronary atherosclerotic heart disease.

T wave morphology and directional changes in myocardial ischemia

(1) subendocardial myocardial ischemia - T wave is towering and symmetrical

After exercise causes acute coronary insufficiency, the subendocardial ischemia can be induced, and the T wave vector leads to the V4 and V5 leads (back to the endocardial surface). Therefore, the T wave is increased and symmetric in these leads and adjacent leads. And changed by an arrow. Such changes are often accompanied by a decrease in the ST segment of subendocardial injury and a shortening of Q-Tc. At this time, the amplitude of the T wave increases, and 10% of patients with coronary heart disease can exceed 0.5 mV or 3 times the amplitude of calm.

(2) Epicardial ischemia - T wave inversion

In the subepicardial ischemia, the T wave vector is back-centrifuged to the outer membrane surface, and the back of the V4 and V5 leads. The lead and its adjacent leads appear T-wave inversion, showing double-symmetry and arrow-like changes. The T wave inversion can occur alone or simultaneously with the ST segment and the U wave anomaly. That is, in the same lead (V4, V5), if the ST segment falls and the symmetry inversion of the T wave is present at the same time, it indicates that there is both subendocardial damage and subepithelial ischemia. The T wave inversion of the V5 lead often occurs later, usually occurring a few minutes after the end of the exercise test, and lasts for a long time, sometimes as long as 40 minutes with Q-Tc prolongation.

A separate T wave inversion often indicates coronary insufficiency in the following situations:

1 inverted T wave is obviously arrow-shaped, symmetrical, and the ST segment stays on the equipotential line for a long time (>0.12 seconds);

2Q-T interval extension;

3 The degree of T wave inversion after exercise is greater than the electrocardiogram record of standing and quiet ventilation for 30 seconds;

4 T wave inversion after exercise is accompanied by a relatively slow heart rate;

5 T wave inversion occurs in I lead (indicating the increase of QRS-T angle). When the inverted T wave is accompanied by ST segment falling, this inverted T wave often appears later, that is, T wave inversion occurs in ST segment. After the fall, that is, when the ST segment decline has disappeared or is disappearing after the exercise, the T wave inversion occurs.

(3) Physiological T wave inversion

T wave inversion is sometimes a normal physiological response caused by exercise, which is characterized by:

The 1T wave is an asymmetrical arrow-like change;

2 no Q-T interval extension;

The 3ST segment stays on the baseline for a short time;

The depth of the 4T wave inversion is <0.2mV.

Physiological T wave inversions are seen in the following factors:

1 excessive ventilation;

2 increased sympathetic tone;

3 The effect of tachycardia on the myocardium;

4 The normal wide QRS-T angle is further widened. At this time, the electrocardiogram has the following characteristics: a calm ECG with a higher R wave accompanied by a lower T wave; a T wave lower or inverted during exercise, especially when the tachycardia is overspeed Oral potassium salt can prevent the occurrence; more common in the elongated and weak body type. The propranolol test can help identify.

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