Pressure and impedance based discrimination of hemodynamic stability

A method of operating an implantable medical device comprising:

• sensing cardiac pressure to obtain cardiac pressure data;
• sensing cardiac impedance to obtain cardiac impedance data;
• determining a phase relationship between the cardiac pressure data and the cardiac impedance data;
• and
• classifying a degree of hemodynamic instability of an arrhythmia based upon the determined phase relationship.

A method of operating an implantable medical device (IMD) comprising:

• sensing cardiac pressure;
• sensing cardiac impedance;
• and
• determining a degree of hemodynamic instability during an arrhythmia based upon a phase relationship between the sensed cardiac pressure and the sensed cardiac impedance.

A method comprising:

• obtaining cardiac pressure data;
• obtaining cardiac impedance data;
• correlating the cardiac pressure data and cardiac impedance data to determine a phase relationship between the cardiac pressure data and the cardiac impedance data;
• determining a hemodynamic stability of a cardiac rhythm based upon the determined phase relationship;
• and
• determining a patient-specific baseline by correlating the pressure data and impedance data during a period of confirmed normal sinus rhythm, wherein determining the patient-specific baseline comprises calculating an area defined by a phase plot between the pressure data and the impedance data,
• wherein determining the hemodynamic stability comprises calculating a next area defined by a phase plot between the pressure data and the impedance data measured during a suspected tachyarrhythmia and comparing the next area to the baseline.