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Sources of error in intra-arterial pressure measurements across a stenosis
R G McWilliams1, I Robertson, S W Smye
1Department of Vascular Radiology, St. James's University Hospital, Leeds, U.K.
Objective:
To investigate potential errors associated with different techniques of intra-arterial pressure measurement at angiography.
Materials And Methods:
An experimental model of an arterial stenosis was developed. Experiments were performed to assess the relevance of catheter position, catheter direction and catheter type on the recorded intraluminal pressure. Transstenotic pressure gradients were recorded with and without angiographic catheters crossing the stenosis.
Results:
At physiological flow rates angiographic catheter type does not influence the recorded pressure. At high flow rates through tight stenoses there is a significant catheter-related difference in recorded pressure adjacent to a stenosis. Downstream pressures may be altered by up to 85 mmHg when standard angiographic catheters are placed across a stenosis.
Conclusion:
The different techniques employed to measure pressure differences across a model stenosis may introduce significant errors up to 85 mmHg. Care must be taken when pressure measurements alone are used to interpret the clinical significance of a stenosis. In low flow conditions there may not be a detectable pressure gradient across a 95% stenosis.