What Are the Common Causes of an Abnormal ECG?

If the patient's ECG shows changes in the ST segment or T wave, special attention should be paid to whether the changes are continuous or dynamic (transient). If the persistence is mostly not caused by myocardial ischemia or coronary heart disease; Related to chest pain, then it is most likely to be unstable angina or myocardial infarction ^[1] .

Abnormal electrocardiogram

If the patient's ECG shows changes in the ST segment or T wave, special attention should be paid to whether the changes are continuous or dynamic (transient). If the persistence is mostly not caused by myocardial ischemia or coronary heart disease; if the ST segment (T wave) changes Related to chest pain, then it is most likely to be unstable angina or myocardial infarction ^[1] .

t ECG abnormal t wave low level

1. The so-called T-wave flatness is the vertical T-wave below 0.2 mV, or 1/10 of the R-wave of the same lead. T wave low level represents a significant abnormality in the process of ventricular activation or a change in myocardial function. T wave depression can also be caused by the relative ischemia of the left ventricular myocardium in the hypertrophy. Of course, in addition to the changes in the amplitude and direction of T waves during heart disease, they are often affected by endocrine, metabolism, and autonomic nervous system activities. For example, when the spirit is stimulated, the T wave can temporarily change from upright to flat, or even upside down. T wave low level does not rule out pathological signs of the heart, but T wave low level is also affected by endocrine, metabolism, autonomic nerve activity and mental stimulation. If conditions permit, it can be further determined.

2. Generally normal ECG means that some measured values are not within the standard limits, but the difference between & iexcl; is small. That is, some measured values are critical left and right, but they can still be regarded as normal; if the next time the ECG is checked, the results of this time are of comparative significance.

3. The roughly normal ECG prompt in English is:

Non-specific T wave abnormality

The minimum voltage criteria for left ventricular hypertrophy (Minimal voltage criteria for LVH (left ventricular hypertrophy)) may be a normal range variation; roughly normal ECG through English prompts: left ventricular hypertrophy combined with abnormal recovery Left ventricular hypertrophy with repolarization abnormality.

4. The principle of life after obsolete inferior and posterior myocardial infarction is to avoid engaging in heavy physical activity, to avoid excessive mental stress and excessive irregular life, and to avoid continuous work for a long time. During the whole recovery period, doctors' supervision and guidance are often required; in addition to the changes in the amplitude and direction of T waves, they are often affected by endocrine, metabolic, and autonomic nervous system activities. For example, when the spirit is stimulated, the T wave can be temporarily flattened or even inverted. In general, the T wave in a lead with a higher R wave should not be lower than 1/10 of the R wave of the lead; the shape of the normal T wave is mostly obtuse, the front branch is long and the rear branch is short; T aVR Inverted; T V 4 6 stand upright; the upright T wave should be larger than 1/10 of the R wave of the same lead, but T V1 0.4 mV and T V2 4 1.5 mV. Anything different is T wave change;

5. Low voltage is the absolute value of Q, R, and S waves of each of the six limb leads below 0.5 mV. If the absolute value of 5 leads is less than 0.5 mV, and the other lead is 0.5 mV 0.9 mV, it is called low voltage tendency. The presence of a low voltage suggests a myocardial disorder or general obesity.

ECG diagnosis

Atrial hypertrophy: divided into left and right atrial hypertrophy or double atrial hypertrophy. The electrocardiogram is characterized by P wave abnormalities. It is more common in chronic pulmonary heart disease, rheumatic mitral valve stenosis or atrial muscle thickening caused by various causes. expand.

Ventricular hypertrophy: divided into left and right ventricular hypertrophy or double ventricular hypertrophy. The electrocardiogram is characterized by abnormal QRS waves. It is more common in rheumatic heart disease, chronic pulmonary heart disease, congenital heart disease, hypertension, or various causes. Thickened ventricular muscles and enlarged ventricular cavity.

Myocardial ischemia: The electrocardiogram is characterized by ST segment and T wave abnormalities, referred to as ST-T changes, and is seen in chronic coronary insufficiency and angina pectoris.

Myocardial infarction: It is divided into acute phase and obsolete phase. The electrocardiogram of acute myocardial infarction is characterized by significant changes in QRS waves and ST-T. ST-T in old myocardial infarction mostly returns to normal, leaving only necrotic Q waves.

Arrhythmia: The heart rhythm of a normal person is sinus rhythm, the rhythm is balanced, and the frequency is 60 to 100 times per minute. Arrhythmias occur if there is an abnormality in the sinoatrial node or conduction system of the origin of the heart.

Sinus arrhythmias: Sinus tachycardia is more than 100 beats per minute, and it is common in exercise or mental stress, fever, hyperthyroidism, anemia, and myocarditis. Sinus heart rate below 60 beats per minute is sinus bradycardia, which is common in hypothyroidism, intracranial hypertension, the elderly, and some drug reactions. The electrocardiogram of sinus arrhythmia is characterized by abnormal PR interval and has little clinical significance.

Pre-phase contraction: referred to as premature beat, which refers to the heart beat that precedes the normal cardiac cycle, and often occurs after a long interval called compensatory interval, which is divided into atrial, borderline and ventricular. The electrocardiogram showed P wave, QRS wave, and ST-T changes, with complete or incomplete compensation intervals. Occasional premature contractions can be seen in normal people, but frequent premature ventricular contractions or the formation of doublets and triplets are more common in many heart diseases.

Ectopic tachycardia: divided into two types of paroxysmal and non-paroxysmal, and also divided into supraventricular or ventricular tachycardia. In addition to fast frequency and irregular rhythm, the former is more normal ECG morphology, the latter QRS Wave width deformity is more common in organic heart disease, non-organic heart disease can also occur.

Flutter and fibrillation: Divided into atrium and ventricle. Atrial flutter and fibrillation are ectopic rhythms with a frequency of 250 to 600 times per minute. The P wave disappears and is replaced by an abnormal "F" wave. It is more common in elderly cardiac degenerative changes, hypertension, coronary heart disease, and pulmonary heart disease. , Hyperthyroidism, etc. Ventricular flutter and fibrillation are malignant arrhythmias. Patients are at risk of life and must be rescued in seconds.