From the Guidelines
Differences in blood pressure between arms are typically caused by several factors, including atherosclerosis, arterial obstructions, anatomical variations in blood vessels, or vascular diseases, and a consistent difference greater than 10 mmHg may indicate underlying cardiovascular issues, as recommended by the 2024 ESC guidelines for the management of elevated blood pressure and hypertension 1.
Causes of Blood Pressure Differences
The causes of blood pressure differences between arms can be attributed to various factors, including:
- Atherosclerosis (narrowing of arteries due to plaque buildup)
- Arterial obstructions
- Anatomical variations in blood vessels
- Vascular diseases like subclavian steal syndrome
- Physical factors such as compression of blood vessels by muscles, bones, or tumors
- Medical conditions including aortic dissection, peripheral artery disease, and certain congenital heart defects
- Age-related changes in blood vessels and conditions like fibromuscular dysplasia
Recommendations for Blood Pressure Measurement
According to the 2024 ESC guidelines, it is recommended to measure blood pressure in both arms at least at the first visit, and if a between-arm difference of >10 mmHg in systolic BP is recorded, all subsequent BP readings should use the arm with the higher BP reading 1. This is supported by other studies, including the 2020 International Society of Hypertension Global Hypertension Practice Guidelines 1.
Importance of Monitoring Blood Pressure Differences
Monitoring blood pressure differences between arms is crucial, as a significant difference (especially over 15 mmHg) may be associated with an increased risk of cardiovascular events. If you notice a significant blood pressure difference between your arms, it is essential to consult a healthcare provider 1.
Key Points to Consider
- A difference of up to 10 mmHg between arms is generally considered normal
- A consistent difference greater than 10-15 mmHg may indicate underlying cardiovascular issues
- Physical factors and medical conditions can contribute to blood pressure differences
- Age-related changes and conditions like fibromuscular dysplasia can further exacerbate these differences
- Measurements should ideally be taken in both arms initially, with subsequent readings done in the arm with the higher reading, as recommended by the 2024 ESC guidelines 1.
From the Research
Causes of Blood Pressure Differences Between Arms
The causes of blood pressure differences between arms are complex and multifaceted. Some of the key factors that contribute to these differences include:
- Vascular disease, such as peripheral arterial disease or cerebrovascular disease 2, 3
- Subclavian stenosis, which can cause a difference in systolic blood pressure between arms 3
- Cardiovascular risk factors, such as age, sex, and ethnicity 4, 5
- Multisystem disorders, which can increase the risk of inter-arm blood pressure differences 5
- Carotid atherosclerosis, which can be associated with blood pressure differences between arms 6
Prevalence of Inter-Arm Blood Pressure Differences
The prevalence of inter-arm blood pressure differences varies widely depending on the population being studied. Some studies have found that:
- 20% of patients have a systolic blood pressure difference of > 10 mmHg between arms 4
- 3.5% of patients have a systolic blood pressure difference of > 20 mmHg between arms 4
- 5.0% of patients have a diastolic blood pressure difference of ≥ 10 mmHg between arms 5
- 31.4% of patients have a systolic inter-arm blood pressure difference between 6-10 mmHg 5
Clinical Significance of Inter-Arm Blood Pressure Differences
Inter-arm blood pressure differences can have significant clinical implications, including: