Estimating Arterial Diastolic Pressure from Ventricular Waveforms
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Solution Overview
Problem
Estimating absolute diastolic pressures in pulmonary and systemic arteries from measurements within the heart's chambers is challenging due to the difficulty in accurately determining these pressures using existing methods.
Innovation Solution
The method involves deriving estimated arterial diastolic pressures by sensing ventricular pressure at the time of a peak minimum rate of change (dP/dtmin) and using this to calculate pulmonary artery or aortic diastolic pressures, along with other hemodynamic parameters like isovolumetric relaxation time and atrial kick pressure, from ventricular pressure waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ventricular pressure is measured to estimate arterial diastolic pressure, then arterial diastolic pressure estimation becomes possible, but measurement accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by identifying and using the dP/dtmin point (the point of maximum negative slope) in the ventricular pressure waveform as a fiducial marker. This specific point in the waveform, which occurs during the isovolumetric relaxation phase, serves as a reliable indicator that correlates with arterial diastolic pressure. By pre-identifying this characteristic point in the ventricular pressure curve, the system can estimate arterial diastolic pressure without requiring direct arterial catheterization, thus improving measurement accessibility while maintaining reliability through the physiological correlation at this specific waveform feature.
2Measurement precision
If direct arterial pressure measurement is performed, then measurement accuracy improves, but device complexity and invasiveness increase
Solution Approach 1:
The patent uses the ventricular pressure waveform and its derivative (dP/dt) as an intermediary to estimate arterial diastolic pressure. Instead of directly measuring arterial pressure through invasive catheterization, the system measures ventricular pressure (which can be obtained from less invasive locations) and uses the dP/dtmin point as a mediator to derive the arterial diastolic pressure value. This intermediary approach allows the system to obtain accurate arterial pressure estimates while avoiding the complexity and invasiveness of direct arterial measurement systems.
Data Source
AI summary
A system and method of determining hemodynamic parameters uses sensed ventricular blood pressure during a portion of ventricular pressure waveform following peak pressure. An estimated arterial diastolic pressure is based upon an amplitude of the sensed ventricular pressure corresponding to a time at which a first derivative of ventricular pressure as a function of time is at a minimum (dP/dtmin). Fill parameters such as isovolumetric relaxation constant, ventricular suction pressure, atrial kick pressure, and transvalve pressure gradient are derived from measured pressures representing minimum ventricular pressure, ventricular diastolic pressure, and diastasis pressure.