Pathological Q waves

Introduction Pathological Q wave is an important feature for the diagnosis of myocardial infarction (MI). The price is economical, quick and convenient, non-invasive, and can be positioned. It can be assessed that the myocardial infarction is caused by an obstruction of the artery to assess whether the degree of occlusion of the artery is completely occluded or partially obstructed, or the likelihood of stenosis; thereby determining whether the intervention is immediate or anticoagulant therapy. Common non-MI diseases include myocarditis, cardiomyopathy, myocardial contusion, progressive muscular dystrophy, scleroderma, amyloidosis, primary or metastatic cardiac tumor, hypertrophic cardiomyopathy, left ventricular hypertrophy, right ventricular hypertrophy , emphysema, pulmonary heart disease, massive pericardial effusion, left bundle branch block, left anterior branch block, right heart, left ventricular false bond.

Cause

Pathological Q wave general meaning:

The 1Q wave width is 0.04s; the 2Q wave amplitude is greater than 1/4 of the same-lead R wave; 3 the Q wave appears on the lead of the Q-wave. There should be no electric quiescent regions in the Q-waveguide connection: (1) Q-wave amplitude of the aVL lead is > 1/2R, Q-wave amplitude of the lower wall is > 60% R; (2) Q-wave time > 0.02s, amplitude > 1/4R; (3) V1, V2 q waves appear in conjunction; (4) QS appears in the V1 and V2 leads. The traditional Q-wave diagnostic criteria is the diagnosis of MI with pathological Q waves. Since it is standardized enough, it is not difficult to diagnose. At the same time, how to diagnose if there is not enough standard? There is no Q wave, no symptoms, no symptoms, no Q wave and other Q-free MI? Therefore, based on the traditional meaning pathological Q wave The concept of an allelic Q wave.

Q wave or similar allelic Q wave caused by non-MI disease:

Also known as pseudo MI. The non-MI Q wave refers to an abnormal Q wave caused by other causes than MI. More common in II, III, aVF, V1 ~ V3 lead, the mechanism may be related to ECG axis shift, cardiac transposition, abnormal cardiac conduction pathway, acute myocardial ischemic injury, localized electrical quiescence, fibrosis or Other components replace the myocardium, interventricular septum hypertrophy and autonomic or indirect stimulation, but not pathological Q waves or allelic Q waves caused by MI.

Common non-MI diseases include myocarditis, cardiomyopathy, myocardial contusion, progressive muscular dystrophy, scleroderma, amyloidosis, primary or metastatic cardiac tumor, hypertrophic cardiomyopathy, left ventricular hypertrophy, right ventricular hypertrophy , emphysema, pulmonary heart disease, massive pericardial effusion, left bundle branch block, left anterior branch block, right heart, left ventricular false bond.

an examination

Related inspection

Doppler echocardiogram electrocardiogram

In the past, according to the electrocardiogram, pathological Q wave, ST segment shift and T wave change, the myocardial infarction was divided into three phases: acute phase, subacute phase and old myocardial infarction, but in recent years, it was found in the early stage of the disease. Most of the typical ECG changes that can not show myocardial infarction, often only ST-T changes, ST segment elevation is one of the earliest ECG manifestations of acute myocardial infarction (AMI), ST segment elevation characteristics and regularity The evolution process is an important criterion for diagnosing AMI.

Differential diagnosis

QRS broadening malformation: Ventricular tachycardia is a tachycardia consisting of more than 3 to 5 wide malformed QRS waves originating from the His bundle bifurcation. Can be caused by heart surgery, cardiac catheterization, severe myocarditis, congenital heart disease, infection, hypoxia, electrolyte imbalance and other reasons. However, in many cases, the cause is not easy to determine.

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). It is the potential change caused by the repolarization of the ventricle on the electrocardiogram. It is also called the ventricular repolarization wave. Many elderly patients with coronary heart disease have a deafness. Wave-lowerness and inversion are the manifestations of coronary heart disease. However, there are many reasons for the change of T-wave morphology. They are not all unique manifestations of heart disease. When judging the significance of T-wave changes, it should be closely combined with clinical practice, and it is not possible to make coronary heart disease rashly. Diagnosis.

Poor R wave in the transition zone: amyloidosis affects coronary arteries can cause angina. About 80% of patients have a pathological Q wave in the chest lead or a poor R wave in the transition zone. Amyloidosis is a myocardial disease caused by the deposition and infiltration of amyloid in the heart. The pathogenesis of cardiacyloidosis is unknown, but it is currently considered to be a protein conformational disease. The folding error of extracellular proteins plays an important role, resulting in insoluble, toxic proteins in the tissue of the -sheet fiber. Protein deposition, which is related to immune, genetic, and inflammation factors. Myocardial amyloidosis may be associated with mutations in aspartate-18 glutamate of the thyroxine transporter.

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