Biomedical Engineering Reference
In-Depth Information
Figure 5.5-20 BioBench Acquisition mode with alarms enabled.
dysfunction could be a side effect of treatment, and liver
disease, where cardiac dysfunction could complicate the
disease.
The most commonly used measure of cardiac perfor-
mance is the ejection fraction. Although it does provide
some measure of intrinsic myocardial performance, it is
also heavily influenced by other factors, such as heart rate
and loading conditions (i.e., the amount of blood
returning to the heart and the pressure against which the
heart ejects blood).
Better indices of myocardial function based on the
relationship between pressure and volume throughout
the cardiac cycle (pressure-volume loops) exist. How-
ever, these methods have been limited because they
require the ability to track ventricular volume continu-
ously during rapidly changing loading conditions. While
there are many techniques to measure volume under
steady-state situations, or at end-diastole and end-systole
(the basis of ejection fraction determinations), few have
the potential to record volume during changing loading
conditions.
Echocardiography can provide online images of the
heart with high temporal resolution (typically 30 frames
per second). Because echocardiography is radiation-free
and has no identifiable toxicity, it is ideally suited to
pressure-volume analyses. Until recently however, its
use for this purpose has been limited by the need for
manual tracing of the endocardial borders, an extremely
tedious and time-consuming endeavor.
The system
Biomedical and software engineers at Premise De-
velopment Corporation (Hartford, CT), in collaboration
with physicians and researchers at Hartford Hospital,
have developed a sophisticated research application
called the ''Cardiovascular Pressure-Dimension Analysis
(CPDA) System''. The CPDA system acquires echocar-
diographic volume and area information from the
acoustic quantification (AQ) port, in conjunction with
ventricular pressure(s) and ECG signals to perform
pressure-volume and pressure-area analyses rapidly. The
development and validation of this system have led to
numerous abstracts and publications at national confer-
ences, including the American Heart Association, the
American College of Cardiology, the American Society of
Echocardiography, and the Association for the Advance-
ment of Medical Instrumentation. This fully automated
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