Dynamic AV Delay Search for Implantable Cardiac Devices
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Solution Overview
Problem
Current implantable medical devices (IMDs) face challenges in dynamically adjusting atrioventricular (AV) timing to account for short-term and long-term changes in a patient's electromechanical conduction, leading to suboptimal ventricular filling and blood ejection due to unphysiologically long AVDSEARCH values during the measurement of intrinsic PR interval.
Innovation Solution
An IMD system with electrodes, sensing circuitry, and processors that dynamically adjust the AVD search parameter by reducing the AVDSEARCH duration based on heart rate, detecting cardiac activity, and identifying conduction block conditions, thereby minimizing prolonged AV delays and optimizing AV timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If AVDSEARCH is prolonged to measure intrinsic PR interval, then measurement capability is improved, but ventricular filling efficiency deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of AVDSEARCH duration based on real-time heart rate detection. When heart rate exceeds a threshold, the system automatically reduces AVDSEARCH from a prolonged value (e.g., 350-400ms) to a shorter value (e.g., 150-200ms), making the search window adaptive rather than static. This resolves the contradiction by allowing prolonged search only when physiologically appropriate, while maintaining shorter durations during high heart rate to preserve ventricular filling efficiency.
Solution Approach 2:
The system changes the AVDSEARCH parameter dynamically based on detected cardiac conditions. By monitoring heart rate and comparing it to predetermined thresholds, the system adjusts the AVDSEARCH duration parameter to optimize both measurement capability and hemodynamic performance. This parameter adaptation allows the system to transition between measurement-optimized and efficiency-optimized states as needed.
2Reliability
If AVDSEARCH is extended for intrinsic conduction measurement, then conduction detection capability is improved, but blood ejection efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts AVDSEARCH duration based on real-time heart rate detection. When heart rate exceeds a threshold, the system automatically reduces AVDSEARCH from a prolonged value (e.g., 350-400ms) to a shorter value (e.g., 150-200ms), making the search window adaptive rather than static. This resolves the contradiction by allowing prolonged search only when physiologically appropriate, while maintaining shorter durations during high heart rate to preserve ventricular filling efficiency.
Solution Approach 2:
The system changes the AVDSEARCH parameter dynamically based on detected cardiac conditions. By monitoring heart rate and comparing it to predetermined thresholds, the system adjusts the AVDSEARCH duration parameter to optimize both measurement capability and hemodynamic performance. This parameter adaptation allows the system to transition between measurement-optimized and efficiency-optimized states as needed.
3Ease of operation
If fixed AVD offset is applied to PR interval, then AVD setting simplicity is improved, but adaptability to heart rate changes deteriorates
Solution Approach 1:
The system performs self-adjustment of AVD based on automatically detected heart rate and intrinsic conduction measurements. Rather than requiring manual reprogramming by a clinician, the device autonomously monitors heart rate, measures intrinsic PR intervals during appropriate conditions, and adjusts the AVD parameter accordingly using a programmable offset. This self-service capability maintains simplicity while adding adaptability to dynamic physiological conditions.
Solution Approach 2:
The system implements a feedback loop where AVD settings are continuously adjusted based on measured intrinsic conduction and detected heart rate. The measured PR interval feeds back into the control algorithm, which applies a programmable offset to determine the optimal AVD. This feedback mechanism enables automatic adaptation to changing cardiac conditions while maintaining operational simplicity through programmable parameters.
Data Source
AI summary
An implantable medical device (IMD) and process are provided comprising one or more electrodes configured to be implanted to define a pacing vector through at least a portion of a ventricle. Sensing circuitry is configured to sense intrinsic atrial activity (As) and intrinsic ventricular activity (Vs). A pulse generator (PG) if provided, and memory configured to store program instructions and an atrioventricular delay search parameter (AVDSEARCH). The AVDSEARCH is an interval of time. One or more processors, that when executing the program instructions, is configured to direct the PG to deliver ventricular pacing pulses based on an atrioventricular delay (AVD) and periodically initiate an AVD search operation utilizing the AVDSEARCH. A heart rate is determined and compared to a threshold. Responsive to determining that the heart rate exceeds the threshold, the AVDSEARCH is reduced, and cardiac activity is detected during the AVD search operation utilizing the reduced AVDSEARCH.