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On the normal scalar ECG. A new classification system considering age, sex and heart position
Insights
This study investigated electrocardiogram (ECG) data in healthy adults, finding that the electrical heart axis shifts leftward with age, weight, and obesity. The Q-wave is proposed as a practical marker for heart position. Keywords: ECG, heart axis, Q-wave, obesity.
Area of Science:
- Cardiology
- Medical Imaging
- Biophysics
Background:
- Electrocardiogram (ECG) analysis is crucial for diagnosing cardiac conditions.
- Understanding normal variations in ECG parameters is essential for accurate interpretation.
- Factors like age, body composition, and heart position can influence ECG readings.
Purpose of the Study:
- To analyze the frontal QRS-axis and Q-wave characteristics in a healthy adult population.
- To investigate the influence of age, sex, weight, and obesity on ECG parameters.
- To explore the utility of the Q-wave as a marker for electrical heart position.
Main Methods:
- A computer-averaged standard 12-lead ECG was recorded from 357 healthy men and women in Lund.
- Visual measurements of ECG deflections and ST-segments were performed.
- Statistical analysis was used to assess relationships between ECG parameters and demographic/anthropometric data.
Main Results:
- The mean frontal QRS-axis shifted leftward with age (significant in men) and increased weight, chest circumference, and obesity index in both sexes.
- Normal frontal QRS-axis ranges were defined as 0° to 90° for men and +15° to 90° for women.
- The Q-wave was found to be a practical marker for heart position, with variations in duration and amplitude observed based on sex, age, and heart position.
Conclusions:
- Age, weight, and obesity significantly influence the electrical heart axis, necessitating consideration of these factors in ECG interpretation.
- The Q-wave offers a practical alternative for assessing electrical heart position compared to the QRS-axis or transitional zone.
- Further research into the Q-wave's diagnostic utility in various cardiac conditions is warranted.
Abstract:
472 randomly selected men and women from the city of Lund were examined for disease in the heart, lungs and for hypertension. 163 men and 194 women who had no symptom or sign of disease were accepted for the further study. The prevalence of various exclusion criterias, such as symptoms and signs of heart disease, lung disease and other diseases which may possibly affect the ECG are reported as well as the distribution of blood pressures in the sample. A computer-averaged standard 12-lead ECG (leads aVL, I, -aVR, II, aVF, III, V1-V6) was recorded. All measurements of ECG-deflections have been made visually using a magnifying glass (6 times). ST-segments were classified according to the Punsar code by independent visual observers as well as by the computer. The mean frontal QRS-axis shifted to the left with advancing age, but the shift was statistically significant only in men. In both men and women there was a leftward shift of the mean frontal QRS-axis with increased weight, increased chest circumference and increased obesity index. The normal range of axis was found to be 0 degrees to 90 degrees in men and +15 degrees to 90 degrees in women. The problems concerning the definition of the electrical heart position is discussed. The concept of a Q-axis is introduced as an alternative way to indicate electrical heart position. There is a statistical significant relationship between the Q-axis and the QRS-axis in the frontal plane, although this relationship is not always apparent in the individual ECG. The presence or absence of a Q-wave in an individual lead was used to denote a lead as being a left ventricular lead or not. Using the Q-wave as a marker of heart position in the individual lead is more practical than to use the QRS-axis or the transitional zone. Duration and amplitude of the Q-wave have been measured. The upper limit of normal duration exceeded 0.03 s in leads aVL and aVF in men but not in women. The R-wave amplitudes proved to vary with age and heart position in men. In women variation of the R-wave amplitude was found with heart position but not with age.(ABSTRACT TRUNCATED AT 400 WORDS)