Devices and method for determining and monitoring a cardiac status of a patient by using PLVDT or PLVST parameters

摘要

The present invention relates to an improved medical device and method for accurately and reliably determining a cardiac status of a patient. An implantable medical device, IMD, comprises a sensor arrangement adapted to sense signals related to mechanical activity of the heart and an activity level sensor arrangement adapted to sense an activity level of the patient. Further, the IMD calculates a percentage of left ventricular diastolic time (PLVDT) for a cardiac cycle corresponding to a relation between a diastolic time interval and a cardiac cycle time interval using the determined systolic and diastolic time intervals or a percentage of left ventricular systolic time (PLVST) for a cardiac cycle corresponding to a relation between a systolic interval time interval and a cardiac cycle time interval. A cardiac status is determined based on the calculated PLVDT (or PLVST) and on an activity level of the patient.

主权项

1. An implantable medical device for determining a cardiac status of a patient, said medical device being connectable to at least one medical lead for contact with tissue of a heart of said patient, said device comprising:
a sensor arrangement adapted to sense cardiac signals related to mechanical activity of said heart and to produce an output signal related to the mechanical activity; an activity level sensor arrangement adapted to sense an activity level of said patient; a cardiac event identifying module adapted to identify predetermined cardiac events in the cardiac signals and to determine a systolic time interval and a diastolic time interval of a cardiac cycle using said identified cardiac events; a calculation module adapted to calculate a percentage of left ventricular diastolic time (PLVDT) for a cardiac cycle corresponding to a relation between a diastolic time interval and a cardiac cycle time interval using said determined systolic and diastolic time intervals or a percentage of left ventricular systolic time (PLVST) for a cardiac cycle corresponding to a relation between a systolic interval time interval and a cardiac cycle time interval using said determined systolic and diastolic time intervals, wherein said calculation module is adapted to determine a rate of change of said PLVDT (or PLVST) and said activity level; and a cardiac status determining module adapted to synchronize the activity level with said calculated PLVDT (or PLVST) over time and to determine a cardiac status based on said calculated PLVDT (or PLVST) and on said activity level and on a rate of change of said PLVDT (or PLVST) and on a rate of change of said activity level;
wherein PLVDT=LVDT/(LVDT+LVST) and PLVST=LVST/(LVDT+LVST); wherein said sensor arrangement includes a light sensing module adapted to emit light into an artery or on vascular tissue and to receive light reflected in blood or transmitted in blood, said light sensing module being adapted to produce a signal corresponding to a light absorption of said blood over time.