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[Measurement of cardiac output by Doppler echocardiography at the 4 cardiac valves]
G Gaudreault1, J G Dumesnil, M H Leblanc
1Institut de Cardiologie de Québec, Hôpital Laval, Sainte-Foy, Canada.
Insights
Doppler-echocardiography can reliably measure cardiac output at the aortic and mitral valves for quantifying shunts and regurgitations. Measurements at the pulmonary and tricuspid valves are less feasible but show strong correlations when possible.
Area of Science:
- Cardiovascular Physiology
- Diagnostic Imaging
- Echocardiography
Context:
- Skepticism exists regarding Doppler-echocardiography for intracardiac output quantification.
- Accurate measurement of shunts and regurgitations is clinically significant.
Purpose:
- To evaluate the feasibility and validity of measuring cardiac output at all four valves using Doppler-echocardiography.
- To assess the reliability of these measurements for clinical applications.
Summary:
- Cardiac output measurements were feasible in 100% of subjects at the aortic valve and 97% at the mitral valve.
- Feasibility was lower at the pulmonary (57%) and tricuspid (29%) valves, often due to poor visualization.
- Excellent correlations were found between aortic stroke volume and stroke volumes at other valves (r > 0.96).
Impact:
- Doppler-echocardiography provides reliable cardiac output measurements, particularly at the aortic and mitral valves.
- These measurements can be valuable for quantifying cardiac shunts and regurgitations when feasible.
- Further research may improve feasibility at less accessible valves.
Abstract:
Many observers remain sceptical with regards to the utilization of Doppler-echocardiographic measurements of intracardiac outputs for the quantification of shunts and regurgitations. In this context, we evaluated the feasibility and validity of measuring output at the level of the four cardiac valves in a population of 35 normal subjects (24 M, 12 F) aged from 23 to 37 years (mean +/- SD = 28 +/- 4). Measurement of stroke volume and output using predetermined criteria was possible in the aortic position in 35 (100%) subjects, in the mitral position in 34 (97%), in the pulmonary position in 20 (57%) and in the tricuspid position in 10 (29%). In 14 subjects (40%), measurement was possible at 2 sites, in 14 (40%) at 3 sites and in 7 (20%) at 4 sites. Inability to measure output was most often due to poor visualization of valvular annulus. There are excellent correlations between aortic stroke volume on the one hand and the mitral (r = 0.97, SEE = 3.41 cc), pulmonary (r = 0.97, SEE = 3.69 cc) and tricuspid (r = 0.96, SEE = 2.77 cc) stroke volumes respectively on the other. These results suggest that reliable measurements of output are feasible in a majority of cases in the aortic and mitral positions but to a much more limited extent in the pulmonary and tricuspid positions; given the small SEE's, they should be useful to quantitate shunts and regurgitations, when feasible.