A novel noninvasive ultrasonic cardiac output monitor: comparison with cardiac magnetic resonance.
BACKGROUND
USCOM, a novel continuous wave Doppler (CWD) device, has been introduced for noninvasive determination of cardiac output (CO). The present study aimed to compare the accuracy and reproducibility of the new device, using cardiovascular magnetic resonance imaging (CMR) as the noninvasive gold standard.


RESULTS
The CO of 56 consecutive patients was prospectively determined by CWD either before or after CMR imaging. The CWD probe was placed in the suprasternal or supraclavicular notch aiming at the aortic valve. Valid CWD signals could be obtained in 45 patients yielding a CO of 5.3+/-1.1 L/min (range, 3.0-7.5 L/min) by CMR and 4.7+/-1.1 L/min by CWD (2.5-8.0 L/min, P = .004), respectively. CWD measurements showed an acceptable agreement with CMR (bias: 0.6+/-1.1 L/min) and a high reproducibility (bias: 0.1+/-0.4 L/min). Higher CO and body mass index (BMI) were identified as sources of inaccuracy in univariate analysis. By multivariate analysis, only CO(CMR) was found to be independently associated with larger variation. Estimated diameters of the left ventricular outflow tract (LVOT), a prerequisite for CO measurement by CWD, correlated only weakly with those measured by CMR.


CONCLUSIONS
Continuous wave Doppler is a feasible technique for measuring cardiac function. Although the overall agreement with CMR was acceptable, CWD showed a trend to underestimate CO. The estimated LVOT diameter by CWD is likely to be an important source of error. Nevertheless, the CWD device could be of clinical use especially for detection of intraindividual hemodynamic changes since a high reproducibility could be demonstrated.
Trinkmann
Frederik
F
1st Department of Medicine, Cardiology, Angiology, Pneumology, Intensive Care, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany.
Doesch
Christina
C
Papavassiliu
Theano
T
Weissmann
Joerg
J
Haghi
Dariusch
D
Gruettner
Joachim
J
Schoenberg
Stefan O
SO
Borggrefe
Martin
M
Kaden
Jens J
JJ
Saur
Joachim
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001021:Aortic Valve / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002302:Cardiac Output; D019719:Diagnostic Equipment; D015150:Echocardiography, Doppler / Q000295:instrumentation*; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D006331:Heart Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation* / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D055815:Young Adult