I. Preparation before “description
The meaning of each waveform
The first thing to clarify is that the ECG records the potential changes during the depolarization and repolarization of cardiac muscle cells.
About electrocardiogram paper
There is a lot of knowledge hidden in the small square! Not only that, the heart rate is calculated by means of ECG paper.
Arrhythmia: HR=60/P-P (or R-R);
Arrhythmia: The number of QRS wave groups within 3s (or 6s) multiplied by 20 (or 10) to calculate the ventricular rate.
1.Normal electrocardiogram
1) Sinus P wave (amplitude: <0.25 mv, time limit: <0.12 s);
2) P-R interval: 0.12~0.20 s;
3) Heart rate: 60~100 beats/min.
Generally everyone can see it by scanning.
Sinus speed and sinus bradycardia mnemonic: small three to five sinus speed slow, three to five between no variation
2, sinus bradycardia = greater than five frames
3, sinus tachycardia = less than three frames
4.Atrioventricular block
Speaking of atrioventricular block, we first remember a couple (P wave represents the wife, QRS represents the husband; you can remember clearly, this analogy will be repeatedly used), the story of the husband’s affair: the
First degree I: the husband comes home late on a regular basis, but still comes back ;
Second degree type I: husband came home later and later at night, sometimes too late and did not come back;
Second degree type II: husband home at night is more regular, but often do not come home;
Third degree: divorced, husband and wife will play their own game!
1) First degree atrioventricular block
Husband comes home late on a regular basis, but still comes back
P-R interval lasts >0.20 s (5 small frames, a square frame), but each P wave is followed by a QRS wave group;
2) Second-degree type I atrioventricular block
Husband comes home later and later at night, sometimes too late and does not return
The P-R interval gradually lengthens until a QRS wave is shed; the first P-R interval after shedding returns to normal, and then gradually lengthens until another QRS wave is shed. This cyclic process is called the Wen’s phenomenon.
(3) Second degree type II AV block
Hubby comes home at night at a fixed time (equal PR interval), but often does not come home (QRS wave group suddenly misses beats)
P-R interval is fixed and QRS wave shedding occurs regularly. For every 2 P waves, 1 P wave is not transmitted down, called 2:1 conduction block; for every 3 P waves, 1 is not transmitted down, called 3:2 conduction block;
(4) Third-degree atrioventricular block
Divorced, husband and wife each play their own game and do not interfere with each other
Generally speaking, P waves are followed by QRS wave groups. However, in third degree AV block, there is no fixed time relationship between P wave and QRS wave group, and P wave frequency is faster than QRS frequency.
5.Atrial premature and ventricular premature
The recipe: atrial premature skimming, ventricular premature broad
The atrial premature contraction is atrial premature; atrial premature skimming is abnormal P wave, which is often referred to as P’ wave.
Two couples are living well, and suddenly a female mistress appears
The QRS wave is generally not deformed, but the interval changes.
Recipe: ventricular preterm contraction (ventricular premature), ventricular premature broad (QRS wave group wide deformation)
The wife’s husband was fine, but suddenly inserted a male mistress (QRS)
Early appearance of broad, deformed QRS waves, QRS interval ≥ 0.12 s; no P waves before it, T waves in the opposite direction to the main wave; compensatory gap is complete.
6.Atrial flutter
① P waves disappear and are replaced by f waves of uniform size, shape and spacing;
② The frequency is 250~350 beats/min;
③ When the fixed ratio of downward transmission, the rhythm is regular, and vice versa the rhythm is irregular.
7.Atrial fibrillation
wife (p-wave) menopause day and night nerves, husband (QRS) scared often afraid to go home and not regular
P wave disappears, replaced by f waves of inconsistent size, shape and spacing, frequency of 350 to 600 times / min, R-R interval absolutely irregular, but can distinguish QRS wave groups.
8.Ventricular tachycardia
Three or more consecutive QRS wave groups of wide distortion, with slightly irregular R-R interval, but with a frequency of about 150~200 beats/min.
9.Ventricular flutter
The P-QRS-T wave disappears and is replaced by a continuous rapid, relatively regular ventricular flutter wave, but with a frequency of 200~250 beats/min.
10.Ventricular fibrillation
Ventricular fibrillation waves of varying size, shape and distance appear, with a frequency of 250~100 beats/min. This is the most serious arrhythmia, if not rescued in time, immediately becomes a straight line!
11.Heart attack
The ECG of heart attack is a dynamic process of change, mainly looking at the ST segment. If you take the exam, the questions will usually give the ECG of “S-T segment elevation” in the acute phase.
Infarct positioning.