Noninvasive Outflow Graft Flow Waveform Assessment Using Echocardiography and the HeartMate 3 Snoopy: A Mock Loop...

Area of Science:

• Cardiovascular Engineering
• Biomedical Engineering
• Medical Device Technology

Background:

• Assessing hemodynamic parameters with left ventricular assist devices (LVADs) is crucial for patient management.
• The HeartWare ventricular assist device (HVAD) allowed instantaneous flow waveform analysis, a capability lacking in the HeartMate 3 (HM3).
• Developing noninvasive methods to monitor HM3 hemodynamics is essential.

Purpose of the Study:

• To evaluate the efficacy of pulsed wave Doppler interrogation of the outflow graft (PWOG) and a novel noninvasive pump data acquisition system (HM3 Snoopy) in obtaining noninvasive flow waveforms (NIFW).
• To determine if these NIFW can predict hemodynamic changes in the HM3.
• To compare NIFW parameters with flow probe (FP)-derived data.

Main Methods:

• A fluid-filled, biventricular failure mock loop model was utilized.
• Fifty-six unique hemodynamic states were created by varying pump speeds, hematocrits, preload, and afterload.
• Noninvasive flow waveform parameters from PWOG and HM3 Snoopy were correlated with FP-derived parameters.

Main Results:

• Moderate correlation was found between NIFW and FP-derived systolic parameters (r range: 0.43-0.81).
• Strong correlation was observed for diastolic parameters (r range: 0.87-0.99).
• Flow waveform amplitude predicted preload (r2 = 0.67), and NIFW parameters adequately predicted afterload (r2 = 0.85).

Conclusions:

• HM3 Snoopy and PWOG show promise for generating flow waveform surrogates noninvasively.
• These methods can effectively detect hemodynamic changes in patients with HeartMate 3 LVADs.
• This facilitates improved monitoring and management of LVAD therapy.