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Diagnostic Tests (II)
Echocardiography - takes a picture of the heart while it beats
Can determine which side of the heart is failing
Can be used to analyze valve function, pericardium, heart wall motion
Systolic failure can be assessed by measuring the ejection fraction of the left ventricle.
Ejection fraction is calculated by dividing stroke volume by the volume of blood remaining in the ventricle after contraction. An ejection fraction of less than 40% indicates heart failure
Note: the measurement of ejection fraction can be potentially deceiving. If the wall of the ventricle has thickened significantly, a safe ejection fraction does not necessarily mean that the heart is pumping an adequate amount of blood.
Radionuclide ventriculography or multi-gated acquisition scanning
Uses a small amount of injected, radioactive dye to take pictures of the heart as it pumps
Can be used to measure ejection fraction
Catheterization - a catheter is passed into the right side of the heart via the jugular vein to measure pressures
This is the most definitive test for heart failure
Measures pressure in the right atrium and ventricle
Measures pressure is the pulmonary artery
Allows for the estimation of the pressures in the left side of the heart by wedging the catheter into a small pulmonary artery
