Evaluation of a new catheter‐mounted electromagnetic velocity sensor during cardiac catheterization

Abstract Pulsatile blood flow was measured with an electromagnetic catheter‐tip velocity transducer in the main pulmonary artery or ascending aorta of 37 patients. This catheter also contains micromanometers for high‐fidelity arterial and ventricular pressure measurements. We found that great vessel blood flow velocity patterns were similar to those obtained by other methods. Cardiac output, calculated from the product of mean flow velocity and vessel cross‐sectional area, was compared with output determined by dye dilution in 28 patients. The correlation coefficient was 0.93 and the regression equation y = 0.93 × + 0.26 liter/min (SEE = 0.8 liter/min). In the remaining nine patients, the flowmeter output was calibrated, in cm 3 /sec, by reference to simultaneous dye‐dilution cardiac output determination 5. Output was then changed by exercise or β‐blockade and measured again by dye dilution. These values were compared to output simultaneously obtained by electromagnetic flowmeter (n = 19). In the patient subgroup of 19 subjects, the correlation coefficient was 0.94 and the regression equation y = 0.87 × + 0.49 liter/min (SEE = 0.72 liter/min). No complications were associated with the use of the catheter. These results suggest that the multisensor catheter offers a safe, reliable technique for obtaining high‐quality pulmonary artery and ascending aortic blood flow and pressure and ventricular pressure waveforms in conscious man.