Mechanically Fused Pacing via Ventricular Acceleration
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Solution Overview
Problem
Current cardiac resynchronization therapy (CRT) methods that rely on electrical signals for pacing may not achieve mechanically synchronous ventricular contractions due to variations in conduction velocities and excitation-contraction coupling, leading to suboptimal hemodynamic benefits.
Innovation Solution
Implementing implantable medical devices with mechanical sensors, such as accelerometers and pressure sensors, to time the delivery of left ventricular pacing pulses based on mechanical activity, optimizing intervals like interventricular delay and pre-ejection interval to achieve mechanical fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LV pacing is timed based on RV sensed electrical events, then pacing therapy can be delivered, but mechanically synchronous contraction cannot be achieved due to variations in conduction velocities and excitation-contraction coupling
Solution Approach 1:
The patent replaces electrical signal-based timing with mechanical signal-based timing. Specifically, it uses mechanical sensors (accelerometers, pressure sensors) to detect mechanical events in the right ventricle and times the left ventricular pacing pulse based on these mechanical events rather than electrical events, thereby achieving mechanically synchronous contraction
Solution Approach 2:
The patent introduces mechanical sensors as intermediaries between the heart's mechanical activity and the pacing delivery system. The mechanical sensors detect mechanical events (such as ventricular wall motion or pressure changes) and provide timing signals that mediate the synchronization between RV mechanical activity and LV pacing delivery
2Ease of operation
If LV pacing is delivered based on pre-defined time intervals before RV sensed events, then pacing therapy is provided, but mechanical fusion is not achieved due to lack of correlation between electrical activation timing and global ventricular excitation pattern
Solution Approach 1:
The patent replaces fixed electrical-interval-based timing with dynamic mechanical-event-based timing. Instead of using pre-programmed intervals before RV sensed electrical events, the system waits for and times pacing delivery based on actual mechanical events detected by sensors, ensuring true mechanical synchronization
Solution Approach 2:
The patent implements feedback by continuously monitoring mechanical events in the right ventricle and using this real-time information to adjust the timing of left ventricular pacing pulses. The mechanical sensor output feeds back to the pacing controller, creating a closed-loop system that adapts to the patient's actual mechanical physiology
3Device complexity
If electrical sensors are used for pacing timing, then the system is simpler, but it cannot account for variations in conduction velocities and excitation-contraction coupling across different heart tissues
Solution Approach 1:
The patent replaces electrical sensing with mechanical sensing to directly measure the mechanical consequences of excitation-contraction coupling. Mechanical sensors detect actual tissue motion and pressure changes, which inherently account for variations in conduction velocities and excitation-contraction coupling without requiring complex electrical signal interpretation
Solution Approach 2:
The patent changes the fundamental parameter being measured from electrical voltage to mechanical motion/pressure. This parameter change allows the system to directly sense the mechanical state of the heart tissue, making it inherently adaptable to variations in tissue properties without requiring complex algorithms or multiple sensors
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for improved cardiac performance by ensuring mechanically synchronous contractions, enhancing the effectiveness of CRT in heart failure patients by aligning pacing with mechanical events rather than electrical events.
Implementation Method 1
an accelerometer located on a lateral wall of the left ventricle and generating an accelerometer signal
Implementation Method 2
a pressure sensor located in the right ventricle and generating a pressure signal
Data Source
AI summary
A medical device system and method for delivering mechanically fused left ventricular cardiac stimulation. A sensor monitors left ventricular acceleration while left ventricular cardiac stimulation is provided at an AV interval. The left ventricular acceleration is used to calculate a mechanical response interval and the mechanical response interval is compared to a desired mechanical response interval. The AV interval is adjusted until the mechanical response interval is equal to the desired mechanical response interval.