Hemodynamic evaluation of pulsatile-flow generating device in left ventricular assist devices

Objective: to investigate the efficiency of a device that generates pulsatile flow during constant-speed axial-flow pump operation for use in left ventricular assist devices.

Materials and methods. The pulsatile flow-generating device, hereinafter referred to as «pulsator», consists of a variable hydraulic resistance made in the form of a hull. A tube of elastic biocompatible material featuring an inner diameter of 11 mm is installed inside it. In the systolic phase of the left ventricle, due to systolic pressure, the elastic tube is fully opened, minimizing resistance to blood ejection. In the diastolic phase, due to suction action of the flow pump operating in constant revolutions, the elastic tube partially closes, creating additional hydraulic resistance to blood flow, which leads to reduced diastolic aortic pressure. Comparative assessment of axial-flow pump operation in pulsating and non-pulsating modes was carried out on a hydrodynamic stand that simulated the cardiovascular system. The following indices were calculated: arterial pressure pulsation (Ip), in-pump flow pulsation (AQ), energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE).

Results. When comparing axial-flow pump operation in pulsatile and continuous mode, arterial pressure pulsation index, in-pump pulsation index, and SHE index increased by 2.13 ± 0.2, 3.2 ± 0.2, and 2.7 ± 0.15 times, respectively, while EER index remained unchanged.

1. Kirklin JK, Naftel DC, Pagani FD, Kormos RL, Stevenson LW, Blume ED et al. Seventh INTERMACS annual report: 15,000 patients and counting. J Heart Lung Transplant. 2015. 34: 1495-1504.

2. Slaughter MS, Rogers JG, Milano CA, Russell SD, Conte JV, Feldman D et al. Advanced heart failure treated with continuous - flow left ventricular assist device. N Engl J Med. 2009. 361: 2241-2251.

3. Miller L, Pagani FD, Russell SD, John R, Boyle AJ, Aa-ronson KD. Use of a continuous-flow device in patients awaiting heart transplantation. N Engl J Med. 2007. 357: 885-896.

4. Crow S, John R, Boyle A, Shumway S, Liao K, Colvin-Adams M et al. Gastrointestinal bleeding rates in recipients of nonpulsatile and pulsatile left ventricular assist devices. JThorac Cardiovasc Surg. 2009; 137: 208-215.

5. Demirozu ZT, Radovancevic R, Hochman LF, Grego-ric ID, Letsou GV, Kar B et al. Arteriovenous malformation and gastrointestinal bleeding in patients with the HeartMate II left ventricular assist device. J Heart Lung Transplant. 2011; 30: 849-853.

6. Wang S, Rider AR, Kunselman AR et al. Effects of the pulsatile flow settings on pulsatile waveforms and hemodynamic energy in a PediVAS centrifugal pump. ASAIO J. 2009; 55: 271-276.

7. Guan Y, Karkhanis T, Wang S, Rider A, Koenig SC, Slaughter MS et al. Physiologic benefits of pulsatile perfusion during mechanical circulatory support for the treatment of acute and chronic heart failure in adults. Ar-tif Organs. 2010; 34: 529-36.

8. Wang S, Kunselman AR, Clark JB, Undar A. In vitro hemodynamic evaluation of a novel pulsatile extracorporeal life support system: impact of perfusion modes and circuit components on energy loss. Artif Organs. 2015; 39: 59-66.

9. Force M, Moroi M, Wang S, Kunselman AR, Undar A. In vitro Hemodynamic Evaluation of ECG-Synchronized Pulsatile Flow Using i-Cor Pump as Short-Term Cardiac Assist Device for Neonatal and Pediatric Population. Artif Organs. 2018; 1: 1-14.

10. Ising MS, Sobieski MA, Slaughter MS, Koenig SC, Gi-ridharan GA. Feasibility of Pump Speed Modulation for Restoring Vascular Pulsatility with Rotary Blood Pumps. ASAIO J. 2015; 61 (5): 526-532.

11. Vandenberghe S, Segers P, Antaki JF, Meyns B, Ver-donck PR. Rapid Speed Modulation of a Rotary Total Artificial Heart Impeller. Artif Organs. 2016; 40: 824-833.

12. Bourque K, Dague C, Farrar D, Harms K, Cohn W et al. In vivo assessment of a rotary left ventricular speed modulation for generating pulsatile flow and phasic left ventricular volume unloading in a bovine model of chronic ischemic heart failure. J Heart Lung Transplant. 2015; 34: 122-131.

13. Soucy KG, Giridharan GA, Choi Y, Sobieski MA, Monreal G, Cheng A et al. Rotary pump speed modulation for generating pulsatile flow and phasic left ventricular volume unloading in a bovine model of chronic ischemic heart failure. J Heart Lung Transplant. 2015; 34: 122131.

14. Pirbodaghi T, Axiak S, Weber A, Gempp T, Vandenberg-he S. Pulsatile control of rotary blood pumps: does the modulation waveform matter? J Thorac Cardiovasc Surg. 2012; 144: 970-977.

15. Tayama E, Nakazawa T, Takami Y et al. The hemolysis test of Gyro C1E3 pump in pulsatile mode. Artif Organs. 1997; 21: 675-679.

16. Buchnev AS, Kuleshov AP, Drobyshev AA, Itkin GP. Hemodynamic evaluation of a new pulsatile flow generation method in cardiopulmonary bypass system. Russian Journal of Transplantology and Artificial Organs. 2019; 21 (3): 69-75.

17. Itkin GP, Bychnev AS, Kuleshov AP, Drobyshev AA. Haemodynamic evaluation of the new pulsatile-flow generation method in vitro. Int J Artif Organs. 2020 Mar; 43 (3): 157-164.

18. RU 2725083 C1. Заявка: 2020103801 от 29.01.2020.

19. Pantalos GM, Koenig SC, Gillars KJ, Giridharan GA, Dan L Ewert DL. Characterization of an Adult Mock Circulation for Testing Cardiac Support Devices. ASAIO J. 2004; 50: 37-46.

20. Shepard RB, Simpson DC, Sharp JF. Energy equivalent pressure. Arch Surg. 1966; 93: 730-734.

21. Saito A, Shiono M, Orime Y, Yagi S, Nakata KI, Eda K et al. Effects of left ventricular assist device on cardiac function: Experimental study of relationship between pump flow and left ventricular diastolic function. Artif Organs. 2001; 25: 728-732.