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Thoracocardiographic-derived left ventricular systolic time intervals
K E Bloch1, S Jugoon, M A Sackner
1Division of Pulmonary Diseases, University of Miami, Mount Sinai Medical Center, Miami Beach, Fla.
Chest
|December 1, 1994
Summary
Thoracocardiography noninvasively estimates left ventricular performance. This study developed a method to accurately track systolic time intervals using thoracocardiography, accounting for body position, for improved clinical assessment.
Area of Science:
- Cardiovascular Physiology
- Noninvasive Cardiac Diagnostics
- Biomedical Engineering
Background:
- Thoracocardiography uses inductive plethysmography to estimate left ventricular performance.
- Accurate, noninvasive tracking of systolic time intervals is crucial for assessing cardiac function.
Purpose of the Study:
- To evaluate the potential of thoracocardiography to accurately track systolic time intervals compared to standard methods.
- To derive and validate an equation for predicting preejection period and ejection time from thoracocardiographic curves.
Main Methods:
- Simultaneous recording of thoracocardiographic curves, carotid pressure pulses, phonocardiogram, and ECG in normal subjects and critically ill patients.
- Development of a regression equation to correct for position-dependent delays in thoracocardiographic waveforms.
- Validation of the derived equation using applanation tonometry and phonocardiography as standard methods.
Main Results:
- Thoracocardiographic ejection onset correlated well with standard preejection period measurements (r=0.92).
- A position-dependent delay in thoracocardiographic curves was identified and quantified (delay = 40 ms + 10 x sine (tilt angle)).
- Corrected thoracocardiography showed close agreement with standard methods for systolic time intervals in patients, with minimal mean differences.
Conclusions:
- Thoracocardiography, when combined with phonocardiography and corrected for position-dependent delays, provides accurate systolic time intervals.
- This noninvasive method offers a reliable alternative for assessing left ventricular performance and systolic timing.