Methods and apparatus to estimate ventricular pressure
An approach for determining an estimated pressure curve for the ventricle of the heart, the method comprising: using data from a motion sensor that has been implanted at the heart to determine the timing of heart cycle events; scaling a reference pressure-time curve including timing of reference heart cycle events in order to fit the reference pressure-time curve to the motion sensor data, the scaling comprising scaling the reference curve along the time axis to fit it to the measured timing of the heart cycle events; and thereby obtaining an estimated pressure-time curve in the form of the scaled reference pressure-time curve.
1. A method of determining an estimated pressure-time curve for a ventricle of a heart, the method comprising:
receiving data from a sensor that has been implanted at the heart;
determining timing of heart cycle events based on the received data;
scaling a reference pressure-time curve using the determined timing of heart cycle events in order to fit the reference pressure-time curve to the received data, the scaling comprising scaling the reference pressure-time curve along a time axis to fit to the determined timing of the heart cycle events; and
determining the estimated pressure-time curve based on the scaled reference pressure-time curve.
2. The method of claim 1 , wherein the determining the estimated pressure-time curve is performed separate to a step of implanting the sensor at the heart.
3. The method of claim 1 , further comprising:
deriving an estimated pressure-motion curve from the estimated pressure-time curve using at least one of the received data or data from a motion sensor.
4. The method of claim 3 , further comprising:
obtaining an estimated pressure-motion loop; and
calculating an area of the estimated pressure-motion loop.
5. The method of claim 4 , wherein the obtaining the estimated pressure-motion loop includes using the estimated pressure-time curve by combining the estimated pressure-time curve with heart motion data obtained from the implanted sensor.
6. The method of claim 1 , wherein the determining the estimated pressure-time curve is carried out in real time with the estimated pressure-time curve being continually updated based on newly obtained data for the timing of the heart cycle events.
7. The method of claim 1 , wherein the heart cycle events include at least one of mitral valve opening, mitral valve closing, aortic valve opening and/or aortic valve closing.
8. The method of claim 1 , wherein the scaling the reference pressure-time curve along the time axis to fit to the measured timing of the heart cycle events to obtain the estimated pressure-time curve is done by scaling the time axis for each of a plurality of intervals between consecutive heart cycle events.
9. The method of claim 1 , wherein the reference pressure-time curve is based on earlier measurements of the same patient or of one or more than one other patients.
10. The method of claim 1 , further comprising:
scaling the reference pressure-time curve using the determined timing of heart cycle events without any use of peak pressure to scale the reference pressure-time curve.
11. The method of claim 1 , further comprising:
using blood pressure data to determine a value indicative of peak ventricular pressure; and
scaling the reference pressure-time curve along a pressure axis based on the determined peak pressure value.
12. The method of claim 1 , wherein the implanted sensor is an accelerometer.
13. The method of claim 1 , further comprising:
implanting the sensor at the heart.
14. A heart monitoring system comprising:
a motion sensor for implantation at a heart to monitor motion of the heart; and
a data processing apparatus arranged to:
receive data from the motion sensor and use the data from the motion sensor or a dedicated sensor for determining timing of heart cycle events;
scale a reference pressure-time curve including timing of reference heart cycle events in order to fit the reference pressure-time curve to the data from the motion sensor, the scaling comprising scaling the reference pressure-time curve along a time axis to fit to the measured timing of the heart cycle events; and
obtain an estimated pressure-time curve in a form of the scaled reference pressure-time curve.
15. The heart monitoring system of claim 14 , wherein the motion sensor is implanted at the heart and the data processing apparatus is coupled to the motion sensor to receive data in real-time.
16. A non-transitory computer-readable storage medium comprising instructions that, when executed, will configure a data processing apparatus to perform:
receiving data from a sensor that has been implanted at a heart;
determining timing of heart cycle events based on the received data;
scaling a reference pressure-time curve using the determined timing of heart cycle events in order to fit the reference pressure-time curve to the received data, the scaling comprising scaling the reference pressure-time curve along a time axis to fit to the determined timing of the heart cycle events; and
determining the estimated pressure-time curve based on the scaled reference pressure-time curve.