In Canada, 2.5% of the population is affected by heart valve disease, with mitral regurgitation (MR) being the second most common. MR can ultimately leads to signs and symptoms of heart failure. Creating an accurate in vitro simulator for MR is crucial not only for gaining a better understanding of the complexities of this disease but also for testing potential therapeutic interventions. However, the mitral valve geometry and the sub valvular apparatus are complex, making any accurate cardiac simulation a challenge.

To create a reproducible in vitro model of various MR conditions.

We modified a previously described left heart in vitro simulator. Six fluorocarbon wires were attached to the leaflets of a mitral valve model to simulate six chordae. Each wire was connected to a load cell and microcontroller to measure chordae tensile force. The tension was manually adjusted using chord locks. Cardiac output (CO) and pressures in the left atrium and ventricle were measured (in triplicate). The simulator was set to a cardiac frequency of 70 bpm. Appropriate chordae tensions were established through trial-and-error tests to produce increasing and controlled levels of MR, with severity classified based on the regurgitation fraction (RF) defined as: (reference CO [i.e. in absence of MR]–measured CO)/reference CO.

We were able to create a reproducible set of 11 different chordae tension configurations simulating different levels of MR, from absence to severe regurgitation ( Fig. 1 ). In absence of MR ([RF] of 0%, control condition), the mean left atrium pressure (mLAP) was 7.6 ± 3.6 mmHg, the mean left ventricle pressure (mLVP) was 55.8 ± 1.2 mmHg, and the CO was 4.6 ± 0.1 L/min. When mimicking a moderate to severe MR (RF of 48 ± 1%), the mLAP became 12.1 ± 5.5 mmHg, the mLVP 28.0 ± 2.5 mmHg, and the CO 2.4 ± 0.1 L/min. Among the configurations tested, we simulated a typical chord rupture by releasing the tension on the chords connected to the P2 scallop (configuration 5). The resulting RF was 30 ± 2%, indicating a moderate MR. When expending the chord rupture to P2 and P3 scallops (configuration 9) the resulting RF was 40 ± 8%, indicating a moderate to severe MR.

We created a simple and reproducible chordae tension regulator to simulate in vitro MR. This system can be used to develop and validate diagnostic imaging tools and test innovative therapeutic interventions.