How to transform a fixed stroke alternating syringe ventricle into an adjustable elastance ventricle

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Medical Device Simulation

Background:

• Current cardiovascular simulators struggle to control ventricular elastance.
• This limitation hinders the simulation of heart failure and ventricular-arterial mechanical mismatch.
• Existing devices often use syringe pumps or elastic chambers, offering limited adjustability.

Purpose of the Study:

• To develop a method for transforming a fixed-stroke syringe pump into a variable elastance ventricle.
• To enable more accurate simulation of cardiovascular pathologies, particularly heart failure.
• To improve the physiological relevance of benchtop cardiovascular models.

Main Methods:

• The study involved two experimental steps to test the proposed method.
• Step 1: Varied peripheral resistance (PHR) while keeping the ventricle and aorta fixed.
• Step 2: Adjusted both ventricular elastance and PHR with a fixed aorta.
• Ventricular pressure-volume (P-V) loops and end-systolic pressure-volume relationships (ESPVRs) were analyzed.

Main Results:

• The modified system demonstrated physiologically relevant behavior in both experimental steps.
• Increasing PHR led to increased systolic pressures and decreased stroke volumes, with a linear ESPVR.
• Adjusting ventricular elastance resulted in ESPVRs with different slopes, maintaining linearity.
• The system successfully simulated conditions with variable ventricular elastance.

Conclusions:

• A fixed-stroke alternating syringe ventricle can be effectively transformed into an adjustable elastance ventricle.
• This advancement allows for more sophisticated simulation of cardiovascular mechanics and pathologies.
• The developed method enhances the utility of benchtop cardiovascular models for research and device testing.