Management of Monophasic Waveforms in the Right Ulnar Artery
Monophasic waveforms detected in the right ulnar artery indicate significant arterial stenosis or obstruction proximal to the measurement site and require urgent vascular imaging to identify the location and severity of occlusive disease. 1
Immediate Diagnostic Workup
Bilateral arm blood pressure measurement is mandatory (Class I, Level B), as an inter-arm systolic blood pressure difference >10-15 mmHg suggests subclavian stenosis. 1 This simple bedside test provides critical information about the severity and laterality of proximal arterial disease.
Complete Duplex Ultrasound Assessment
Perform comprehensive duplex ultrasound evaluation that includes: 1
- Peak systolic velocities at stenotic sites: 50% stenosis corresponds to PSV ≥230 cm/s, while 70% stenosis corresponds to PSV ≥340 cm/s 1
- Velocity ratios to quantify stenosis severity 1
- Vertebral artery flow direction assessment: >90% of patients with at least 50% proximal subclavian stenosis demonstrate vertebral artery flow reversal 1
- Hyperemia testing if subclavian steal syndrome is suspected 1
Risk Stratification and Etiology
Proximal subclavian stenosis or occlusion is most commonly atherosclerotic in origin, and the presence of monophasic waveforms indicates systemic atherosclerosis requiring comprehensive cardiovascular risk assessment. 1 The prevalence of subclavian stenosis is 11.4% in patients with peripheral arterial disease. 1
Indications for Revascularization
Revascularization should be considered (Class IIa, Level B) in the following clinical scenarios: 1
- Symptomatic patients with TIA/stroke related to subclavian disease
- Coronary subclavian steal syndrome
- Ipsilateral hemodialysis access dysfunction
- Severe upper extremity ischemia
- Planned coronary artery bypass grafting using the ipsilateral internal mammary artery
Endovascular revascularization may be considered over surgery (Class IIb, Level B) due to lower complication rates, despite similar long-term outcomes. 1
Medical Management
All patients require aggressive cardiovascular risk modification: 1
- Dual antiplatelet therapy should be initiated if revascularization is planned 1
- High-intensity statin therapy is essential 1
- Blood pressure control targeting guideline-recommended goals 1
- Smoking cessation is mandatory 1
Common Pitfall to Avoid
Do not confuse monophasic waveforms in arteries (indicating vascular obstruction requiring urgent imaging) with monophasic waveforms detected during nerve conduction studies or Doppler ultrasound of sacroiliac joints (which have entirely different clinical implications). 2 The context of ulnar artery Doppler assessment clearly indicates vascular pathology requiring the vascular workup outlined above.