From the Guidelines
A difference in blood pressure between arms can be a sign of an aortic aneurysm, particularly if the difference is greater than 10 mmHg, and immediate medical evaluation is recommended. This discrepancy occurs because an aneurysm in the aorta or its major branches can disrupt normal blood flow, causing reduced pressure in one arm compared to the other. According to the 2024 ESC guidelines for the management of elevated blood pressure and hypertension 1, if systolic BP differs by >10 mmHg between arms, subsequent measurements are obtained using the arm with the higher BP value. The blood pressure difference happens because the aneurysm can partially obstruct blood flow to one of the arteries that supply the arms (subclavian or brachial arteries), resulting in lower pressure on the affected side. Other conditions that can cause blood pressure differences between arms include atherosclerosis, subclavian steal syndrome, and aortic dissection, so proper diagnosis is essential for appropriate treatment.
Some key points to consider:
- The American Heart Association recommends measuring blood pressure in both arms at the first examination to detect coarctation of the aorta and upper extremity arterial obstruction 1.
- The 2020 International Society of Hypertension global hypertension practice guidelines suggest using validated automated upper arm cuff devices with appropriate cuff size for the individual patient and measuring BP in both arms simultaneously, using the arm with the higher BP if there is a consistent difference 1.
- It is essential to seek immediate medical evaluation if a significant blood pressure difference between arms is noticed, as this could indicate a potentially life-threatening condition.
In terms of management, the guidelines suggest:
- Controlling blood pressure with a titratable agent to balance the risk of stroke, hypertension-related rebleeding, and maintenance of cerebral perfusion pressure 1.
- Considering morphological and hemodynamic characteristics of the aneurysm when discussing the risk of aneurysm rupture 1.
- Using imaging tests such as CT angiogram or ultrasound to assess for an aneurysm 1.
Overall, immediate medical evaluation and proper diagnosis are crucial for appropriate treatment and to prevent potentially life-threatening complications.
From the Research
Aneurysm and Blood Pressure Difference Between Arms
- A difference in systolic blood pressure readings between arms can predict an increased risk of cardiovascular events and all-cause mortality over 10 years in people with hypertension 2
- An interarm difference in systolic blood pressure of 10 mm Hg or more is associated with an increased risk of all-cause mortality (adjusted hazard ratio 3.6,95% confidence interval 2.0 to 6.5) 2
- Increased systolic blood pressure is an independent predictor of aneurysm enlargement in patients with an untreated type II endoleak after endovascular abdominal aortic aneurysm repair (EVAR) 3
Association Between Blood Pressure and Aneurysm Rupture
- Hypertension is significantly associated with an increased rupture risk of intracranial aneurysms (OR = 2.559,95%CI = 2.161-3.030, P = 0.000) 4
- The absence of regular blood pressure monitoring is significantly associated with an increased risk of intracranial aneurysm rupture, emphasizing the importance of implementation of regular blood pressure monitoring in hypertensive patients with intracranial aneurysms 4
Diagnostic Criteria for Aneurysms
- Interarm systolic BP differential is a classic sign of acute aortic dissection (AAD), but its diagnostic accuracy is limited 5
- Bilateral systolic BP differentials >20 mm Hg are associated with non-traumatic AAD, but the poor diagnostic accuracy and potential variability in measurement limits its clinical usefulness 5