Admittance derived stroke volume for determination of hemodynamic stability during atrial and ventricular arrhythmias

Implantable cardioverter defibrillators (ICDs) are medical devices proven to prevent sudden cardiac death due to ventricular arrhythmias. Their decisions are based upon intra-cardiac electrograms (IEGM). This is incomplete information since up to 5% of implantable cardioverter defibrillator (ICD) shocks are inappropriate. Receiving a shock is associated with increased mortality as well as emotional trauma. In contrast, physicians determine whether to shock a patient out of a rapid rhythm by determining if the arrhythmia is hemodynamically unstable or stable. An unstable arrhythmia is identified by decreased forward stroke volume (SV) and resultant low blood pressure (BP). It would be ideal to have beat-by-beat SV available to the ICD to assist in the delivery of therapies. A system that utilizes the right ventricular (RV) shocking lead of an ICD to measure the electrical admittance in the RV is proposed for measuring continuous SV. For this method to work, a signal processing technique to remove noise artifacts related to lead motion and respiration must be developed.