1. Left atrial hypertrophy
The P-wave widens and appears as a bimodal pattern, with the most prominent in leads I, II, and aVL, also known as mitral valve type P-wave. The PR segment is shortened, and the P-wave in lead V1 first appears positive, followed by a deep and wide negative wave.
2. Right atrial hypertrophy
The P-wave is sharp and towering, with an amplitude greater than 0.25mV. Due to the increase of the downward P-vector, it is most prominent in leads II, III, and aVF of the electrocardiogram, known as the “lung type P-wave”.
3. Left ventricular hypertrophy
(1) The QRS complex voltage increases: RV5>2.5mV, RV5+SV1>4.0mV (male) or>3.5mV (female).
(2) The electrocardiogram axis deviates to the left.
(3) The QRS complex time was extended to 0.10-0.11 seconds.
(4) ST-T changes, with R waves dominant in leads, where T waves are low, flat, bidirectional, or inverted.
4. Right ventricular hypertrophy
(1) V1 lead R/S>1, V5 lead R/S<1, and the QRS complex of V1 or V3 R shows RS, RSR ′, R, or QR patterns.
(2) RV1+SV5>1.2mV, R/Q or R/S>1 for aVR leads, RaVR>0.5mV.
(3) The electrocardiogram axis deviates to the right, and in severe cases, it can be>+110 °.
(4) V1 or V3 R and other right chest leads have ST-T downshifting>0.05mV, and T-waves are low, flat, bidirectional, or inverted.
5. Myocardial infarction
(1) Ischemic T wave changes: Ischemia occurs on the endocardial surface, with high and upright T waves; If it occurs on the epicardial surface, symmetrical T-wave inversion occurs.
(2) Injury type S-T segment change: The leads facing the injured myocardium show elevation of the S-T segment, which can form a single-phase curve with significant elevation.
(3) Necrosis type Q-wave appearance: Abnormal Q-waves (width ≥ 0.04s, depth ≥ 1/4R) or QS waves appear in leads facing the necrotic area.
6. Atrial premature contractions
(1) The early appearance of atrial P ‘differs in morphology from sinus P wave.
(2) P ′ – R interval ≥ 0.12s.
(3) There is a normal QRS complex after atrial P ‘wave.
(4) Intermittent compensation is incomplete.
7. Ventricular premature contractions
(1) The QRS-T complex with early onset of broad malformations does not have any ectopic P-waves before it.
(2) The QRS time limit is often ≥ 0.12s.
(3) The direction of the T-wave is opposite to the direction of the QRS main wave.
(4) There are often complete compensatory intervals.
8. Junctional premature contractions
(1) The QRS complex that appeared in advance has a basically normal morphology.
(2) The occurrence of retrograde P ‘wave can occur before QRS (P’ – R<0.12s), after QRS (R-P ‘<0.20s), or overlap with QRS.
(3) There are often complete compensatory intervals.
9. Paroxysmal supraventricular tachycardia
(1) Equivalent to a series of continuous and rapid atrial or junctional premature beats, with a frequency of 150-250/min and a regular rhythm.
(2) The QRS complex morphology is basically normal, with a time of ≤ 0.10s.
(3) There is no change in ST-T, or the S-T segment shifts downward and the T-wave is inverted during the onset.
10. Atrial fibrillation
(1) The P-wave disappears and is replaced by F-waves of varying sizes, spacing, and shapes, with frequencies ranging from 350 to 600 beats per minute, with the V1 lead being the most prominent.
(2) The ventricular rhythm is absolutely irregular, with a ventricular rate typically between 120 to 180 beats per minute.
(3) The QRS complex morphology is usually normal. When the ventricular rate is too fast, indoor differential conduction occurs, and the QRS complex widens and deforms.
11. Ventricular fibrillation
(1) The P-wave disappears and is replaced by F-waves of varying sizes, spacing, and shapes, with frequencies ranging from 350 to 600 beats per minute, with the V1 lead being the most prominent.
(2) The ventricular rhythm is absolutely irregular, with a ventricular rate typically between 120 to 180 beats per minute.
(3) The QRS complex morphology is usually normal. When the ventricular rate is too fast, indoor differential conduction occurs, and the QRS complex widens and deforms.
12. Atrioventricular block
(1) First degree atrioventricular block: ① QRS complex is present after sinus P wave. ② The P-R interval was extended by ≥ 0.21 s.
(2) Second degree type I atrioventricular block: ① The P-wave pattern appears, and the P-R interval is gradually prolonged until ventricular leakage occurs (there is no QRS complex after the P-wave). ② After a missed beat, the P-R interval tends to shorten again, and then gradually extends until the missed beat repeats itself The time and morphology of the QRS complex are mostly normal.
(3) Second degree type II atrioventricular block: ① P-R interval is constant (normal or prolonged). ② Partial absence of QRS complex after P-wave (occurrence of ventricular leakage) The ratio of atrioventricular conduction is generally 2:1 or 3:2, etc.
(4) Third degree atrioventricular block (complete atrioventricular block): ① There is no fixed relationship between the P-wave and QRS complex, and the spacing between P-P and R-R has their own fixed patterns. ② Atrial rate>ventricular rate. ③ The QRS complex has normal or wide malformation morphology.
The above are common types of abnormal ECG. There are now portable ECG recorders (such as Plus1Health) that can monitor and record ECG in real-time at any time, automatically analyze and generate reports. There is also an ECG, which can be accessed anytime and anywhere, making it convenient for doctors to refer to.
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