System and method for measuring ventricular evoked response using an implantable medical device

• US 7,440,804 B1
• Filed: 12/28/2004
• Issued: 10/21/2008
• Est. Priority Date: 12/28/2004
• Status: Expired due to Fees

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Koh, Steve, Min, Xiaoyi
• Primary Examiner(s): Layno; Carl H.
• Assistant Examiner(s): Oropeza; Frances P
• Application Number:
  US11/025,220
• Time in Patent Office: 1,393 Days
• Field of Search: 600/373, 600/374, 600/377, 600/393, 600/509, 607/4, 607/5, 607/6, 607/9, 607/11, 607/116, 607/122
• US Class Current: 607/28
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

Techniques are provided for measuring ventricular evoked response within the heart of a patient during atrial fibrillation. An intrinsic ventricular depolarization (i.e. a QRS complex) is sensed within the right ventricle and then a pacing pulse is applied to the left ventricle prior to intrinsic depolarization thereof. In this manner, the left ventricle contracts solely in response to the pacing pulse and possible fusion between the pacing pulse and a conducted P-wave/A-pulse from the atria is avoided. The evoked response generated in the left ventricle is then measured by the pacemaker. The technique permits reliable detection of left ventricular evoked response, even during atrial fibrillation when atrial contractions are frequent and erratic, but the technique may also be employed during normal sinus rhythm. Features of the evoked response are analyzed to detect heart failure, evaluate its severity and track its progression. Appropriate therapy is then automatically delivered to the patient.

Claims

1. A method for measuring evoked response within the heart of a patient via an implantable medical device, the method comprising:

sensing an intrinsic ventricular depolarization within a ventricular chamber of the heart;

delivering a pacing pulse in response thereto to the opposing ventricular chamber prior to intrinsic depolarization thereof;

detecting an evoked response generated in response to the pacing pulse;

tracking changes in the evoked response over time as a surrogate for a patient condition;

detecting atrial fibrillation (AF) and wherein sensing the intrinsic ventricular depolarization, delivering the pacing pulse in response thereto, and detecting the evoked response are only performed during AF.

2. The method of claim 1 wherein, if the heart is not subject to an ongoing AF, then performing the alternative steps of:

reducing an atrioventricular delay by an amount sufficient to avoid fusion between atrial depolarization signals conducted from the atria and ventricular pacing pulses;

delivering a ventricular pacing pulse; and

measuring the evoked response generated in response to the pacing pulse.