Sources of error in intra-arterial pressure measurements across a stenosis

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. Trans-stenotic 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