P1.04 Invasive Assessment of Aortic Pressure Waves: Comparison Between Pressure Wire and Fluid Filled Catheter

Abstract

Introduction

Parameters of wave reflection (augmentation pressure - AP or augmentation index – AIx) are powerful independent prognostic markers in patients with coronary artery disease. However, the invasive investigation of arterial waveforms is still confined to expensive equipment. The aim of this study was the comparison of modern standard fluid filled catheters using a pressure transducer (Sensis, Siemens) against a high fidelity (frequency response flat from 0–25 Hz) guidewire based pressure sensor (Pressure Wire®, Radi medical), with focus on AP and AIx.

Design and Methods:

Pressure curves were recorded at the level of the ascending aorta simultaneously using a 6 French fluid filled catheter and a Pressure Wire® for about 20 seconds in 12 patients undergoing invasive assessment of coronary artery lesion severity. Fluid filled catheters were carefully used to avoid bubbles so as to obtain frequency response > 10 Hz and damping coefficient around 0.2. The recorded sequences were analysed with Fourier analysis (modulus and phase shift) in the frequency domain as well as by the means of time domain analysis for inflection pressure determination (2^nd respectively 4^th derivative in time).

Results:

The mean correlation of the wave forms was R = 0.998. The mean difference for AIx was 5.79 % with a standard deviation of 7.69 %. The mean difference in AP was 3.74 mmHg with a standard deviation of 4.63 mmHg. For modulus and phase we found negligible differences in amplifications and shifts in the range from 1–10 Hz.

Perspective:

The preliminary results of this small study provide evidence that modern transducer systems with carefully prepared fluid-filled tubing and connections can deliver useful information for pulse wave analysis and should be investigated more intensively.