From the Guidelines
A blood pressure difference of 20 mmHg or greater between arms is concerning for aortic dissection. This finding, while not universally present in all cases, represents a significant clinical warning sign that warrants immediate further investigation 1. The difference occurs because the dissection can obstruct blood flow to one arm, creating unequal pressures. When evaluating a patient with suspected aortic dissection, bilateral blood pressure measurements should be taken as part of the initial assessment. Other concerning signs include:
- Sudden-onset severe chest or back pain described as tearing or ripping
- Mediastinal widening on chest X-ray
- Signs of end-organ malperfusion If a significant blood pressure difference is detected, immediate advanced imaging (CT angiography, MRI, or transesophageal echocardiography) should be obtained while simultaneously initiating blood pressure control with IV beta-blockers (such as esmolol or labetalol) to reduce heart rate and blood pressure, with a target systolic blood pressure of 100-120 mmHg and heart rate of less than 60 beats per minute 1. This inter-arm blood pressure difference is particularly significant when accompanied by other risk factors such as hypertension, Marfan syndrome, bicuspid aortic valve, or family history of aortic disease. The management of acute aortic dissection should be centralized in experienced centers and managed by aorta teams, with the aim of reducing aortic wall stress to avoid further extension of dissection with possible rupture or malperfusion 1.
From the Research
Blood Pressure Difference in Aortic Dissection
- A concerning blood pressure difference for aortic dissection is not explicitly defined in the provided studies, but several studies suggest that an inter-arm difference in blood pressure (IADBP) is characteristic of acute aortic dissection (AAD) 2, 3, 4.
- One study found that an IADBP of >15 mm Hg or >20 mm Hg was associated with type A aortic dissection (TAAD) 2.
- Another study found that a systolic BP differential >20 mm Hg was significantly associated with AAD, but had poor diagnostic accuracy 3.
- A study on bilateral upper-extremity blood pressure measurements found that 19% of patients had a systolic or diastolic interarm blood pressure difference of more than 20 mm Hg, but this variation was unrelated to age, gender, race, mean arterial pressure, cardiovascular risk factors, or discharge diagnosis 4.
- The American Heart Association and other organizations do not provide a specific blood pressure difference threshold for concern, but rather recommend monitoring blood pressure and other clinical signs and symptoms to diagnose and manage aortic dissection 5, 6.
Key Findings
- IADBP is a characteristic of AAD, particularly TAAD 2.
- An IADBP of >15 mm Hg or >20 mm Hg may be associated with TAAD 2.
- A systolic BP differential >20 mm Hg is associated with AAD, but has poor diagnostic accuracy 3.
- Bilateral upper-extremity blood pressure measurements have a wide degree of interarm variation, with 19% of patients having a systolic or diastolic interarm blood pressure difference of more than 20 mm Hg 4.
Clinical Implications
- Clinicians should be aware of the potential for IADBP in patients with AAD, particularly TAAD 2, 3.
- Monitoring blood pressure and other clinical signs and symptoms is crucial for diagnosing and managing aortic dissection 5, 6.
- Further research is needed to determine the clinical significance of IADBP and to develop evidence-based guidelines for its use in diagnosing and managing AAD 2, 3, 4.