What is the condition called when there is a significant difference in blood pressure between the two upper extremities?

Inter-Arm Blood Pressure Difference: Clinical Significance and Diagnosis

A significant difference in blood pressure between the upper extremities is called inter-arm blood pressure difference (IASBPD), with a difference of >15-20 mmHg being suggestive of subclavian or innominate artery stenosis, and a difference of ≥20 mmHg strongly suggesting possible aortic dissection when accompanied by chest or back pain.

Definition and Measurement

• Blood pressure should be measured in both arms at least once during the initial assessment of patients 1
• Proper measurement technique is essential:
  • Use validated devices with appropriate cuff size based on arm circumference
  • Position the patient seated comfortably after 5 minutes of rest
  • Place cuffs at heart level with back and arm supported 1, 2
• Sequential arm measurement is considered sufficiently reliable, though simultaneous measurement devices exist 1
• When a difference is detected, additional measurements should be taken to confirm consistency 1

Clinical Significance of Inter-Arm Differences

Threshold Values:

• 10-15 mmHg difference: Requires confirmation and follow-up

  • If systolic BP differs by >10 mmHg between arms, subsequent measurements should be obtained using the arm with the higher BP value 1
  • Occurs in approximately 20% of hypertensive individuals 3

• >15-20 mmHg difference: Abnormal and clinically significant

  • Suggestive of subclavian or innominate artery stenosis 1
  • Associated with increased risk of peripheral arterial disease (PAD) with a risk ratio of 1.91 4
  • Requires further cardiovascular risk assessment 1, 2

• ≥20 mmHg difference: Highly significant finding

  • Strong indicator of possible aortic dissection, especially when accompanied by chest or back pain 2
  • Requires urgent further investigation 2
  • Has a negative likelihood ratio of 0.07-0.17 for aortic dissection if the difference is not present 2

Associated Conditions

Inter-arm blood pressure differences are associated with:

1. Subclavian artery stenosis

   • IASBPD >15-20 mmHg is suggestive of subclavian or innominate artery stenosis 1
   • Patients with PAD are at increased risk of subclavian artery stenosis 1

2. Peripheral Arterial Disease (PAD)

   • IASBPD of ≥10 mmHg is associated with PAD with a risk ratio of 2.22 4
   • IASBPD of ≥15 mmHg maintains significant association with PAD (risk ratio 1.91) 4

3. Aortic Dissection

   • IASBPD ≥20 mmHg with chest/back pain strongly suggests possible aortic dissection 2
   • Requires immediate imaging and surgical consultation if suspected 2

4. Left Ventricular Hypertrophy

   • IASBPD ≥10 mmHg is associated with increased left ventricular mass index 4, 5

5. Increased Arterial Stiffness

   • Associated with higher brachial-ankle pulse wave velocity 4, 5

Clinical Approach to Inter-Arm Differences

1. Initial Detection:

   • Measure BP in both arms at the initial visit 1
   • If difference >10 mmHg, confirm with additional measurements 1

2. Management Based on Difference:

   • 10-15 mmHg: Use arm with higher BP for subsequent measurements 1
   • >15-20 mmHg: Consider further cardiovascular risk assessment 1
   • ≥20 mmHg: Urgent investigation, especially with chest/back pain 2

3. Special Considerations:

   • In the absence of symptoms (e.g., arm claudication or symptoms of vertebral artery steal) with differences of 15-20 mmHg, no further imaging or intervention may be warranted 1
   • For accurate ABI measurement in PAD assessment, identifying the arm with highest systolic pressure is required 1

Common Pitfalls and Caveats

• Normal variation can account for some inter-arm differences; up to 18% of hypertensive individuals may have differences exceeding 10 mmHg without pathology 3
• Proper measurement technique is crucial to avoid false positives 1
• Individual patients may have mean between-arm differences in blood pressure of up to 10 mmHg without pathology 6
• Avoid relying on a single measurement; confirm significant differences with repeated measurements 1
• Consider patient factors that may influence IASBPD, including female gender, hypertension, and high body mass index 5

In summary, inter-arm blood pressure differences should be systematically assessed during initial patient evaluation, with differences exceeding 15-20 mmHg warranting further investigation for potential vascular pathology, particularly subclavian stenosis or, when accompanied by chest pain, aortic dissection.