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We are developing a new left atrial assist device (LAAD) for patients who have heart failure with preserved ejection fraction (HFpEF). This study aimed to assess the hemodynamic effects of the LAAD under both normal heart conditions and various diastolic heart failure (DHF) conditions using a mock circulatory loop. A continuous-flow pump that simulates LAAD, was placed between the left atrial (LA) reservoir and a pneumatic ventricle that simulated a native left ventricle on a pulsatile mock loop. Normal heart (NH) and mild, moderate, and severe DHF conditions were simulated by adjusting the diastolic drive pressures of the pneumatic ventricle. With the LAAD running at 3200 rpm, data were collected at 60, 80, and 120 bpm of the pneumatic ventricle. Cardiac output (CO), mean aortic pressure (AoP), and mean LA pressure (LAP) were compared to evaluate the LAAD performance. With LAAD support, the CO and AoP rose to a sufficient level at all heart rates and DHF conditions (CO; 3.4-3.8 L/min, AoP; 90-105 mm Hg). Each difference in the CO and the AoP among various heart rates was minuscule compared with non-pump support. The LAP decreased from 21-23 to 17-19 mm Hg in all DHF conditions (difference not significant). Furthermore, hemodynamic parameters improved for all DHF conditions, independent of heart rate. The LAAD can provide adequate flow to maintain the circulation status at various heart rates in an in vitro mock circulatory loop.

Objectives: Many patients with heart failure have preserved ejection fraction but also diastolic dysfunction, with no effective therapy. We are developing a new pump (left atrial assist device, LAAD) for implantation at the mitral position to pump blood from the left atrium to sufficiently fill the left ventricle. The purpose of the initial in vitro study was to demonstrate that the LAAD can reduce left atrial pressure (LAP) and increase cardiac output (CO) while maintaining arterial pulsatility and normal aortic valve function using a proof-of-concept device., Methods: The LAAD concept was tested at 3 pump speeds on a pulsatile mock loop with a pneumatic pump that simulated the normal function of the native ventricle as well as 3 levels of diastolic heart failure (DHF 1, 2, and 3) by adjusting the diastolic drive pressure to limit diastolic filling of the ventricle., Results: Without the LAAD, CO and aortic pressure (AoP) decreased dramatically from 3.8 L/min and 100 mm Hg at normal heart condition to 1.2 L/min and 35 mm Hg at DHF 3, respectively. With LAAD support, both CO and AoP recovered to normal heart values at 3200 rpm and surpassed normal heart values at 3800 rpm. Furthermore, with LAAD support, LAP recovered to almost that of the normal heart condition at 3800 rpm., Conclusions: These initial in vitro results support our hypothesis that use of the LAAD increases CO and AoP and decreases LAP under DHF conditions while maintaining arterial pulsatility and full function of the aortic valve., (Copyright © 2020 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

We are developing a left atrial assist device (LAAD) to pump blood from the left atrium to the left ventricle for patients who have heart failure with preserved ejection fraction (HFpEF). This study aimed to assess the hemodynamics with the LAAD implanted at two different levels: the mitral valve (MV) level, after removing the MV; and the supravalvular level, preserving MV function conditions using an in vitro mock circulatory loop. Normal heart and mild, moderate, and severe diastolic heart failure conditions were simulated, and the LAAD was set at three different speeds. Without the LAAD support, cardiac output (CO) decreased from 3.7 to 1.1 L/min, aortic pressure (AoP) decreased from 100 to 33 mm Hg, and left atrial pressure (LAP) increased from 16 to 23 mm Hg as the diastolic function became impaired. With high pump support after removing the MV, CO and AoP readings were comparable with those for preserved MV function (CO reached 3.9-4.1 L/min, AoP reached more than 110 mm Hg, and LAP dropped to 16-17 mm Hg under both conditions at high pump speeds). In the mock circulatory loop, our LAAD appeared to have sufficient ability to maintain the hemodynamic status at both positions., Competing Interests: Disclosure: K.F., D.J.H., J.H.K., and R.C.S. are co-inventors of the LAAD. The other authors have no conflicts of interest to report., (Copyright © ASAIO 2020.)

An advanced ventricular assist device (VAD), which is under development in our institution, has specific features that allow changes in the axial rotor position and pump performance by intrapump pressure difference. However, performance could be influenced by the pump orientation because of the effect of gravity on the rotor position. The purpose of this study was to evaluate the effects of pump orientation on the pump performance, including pulse pressure and regurgitant flow through the pump when the pump was stopped. Bench testing of the VAD was performed on a static or pulsatile mock loop with a pneumatic device to simulate the native ventricle. The pump performance, including pressure-flow curve, pulsatility, and regurgitant flow, was evaluated at several angles, ranging from -90° (inlet pointed upward) to +90° (inlet pointed downward) at pump speeds of 2000, 2500, 3000, and 3500 rpm. The pump performance was slightly lower at +90° at all rotational speeds, compared with -90°. The pulse pressure on the pulsatile mock loop (80 bpm) was 50 mm Hg without pump support, remained at 50 mm Hg during pump support, and was not changed by orientation (-90°, 0°, and +90°). When the pump was stopped, the regurgitant flow was near 0 L/min at all angles. Pump orientation had a minor effect on pump performance, with no effect on pulse pressure or regurgitant flow when the pump was stopped. This indicates that the effect of gravity on the rotor assembly is insignificant., (© 2020 International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

We are developing a novel type of miniaturized left ventricular assist device that is configured for transapical insertion. The aim of this study was to assess the performance and function of a new pump by using a Virtual Mock Loop system for device characterization and mapping. The results, such as pressure-flow performance curves, from pump testing in a physical mock circulatory loop were used to analyze its function as a left ventricular assist device. The Virtual Mock Loop system was programmed to mimic the normal heart condition, systolic heart failure, diastolic heart failure, and both systolic and diastolic heart failure, and to provide hemodynamic pressure values before and after the activation of several left ventricular assist device pump speeds (12,000, 14,000, and 16,000 r/min). With pump support, systemic flow and mean aortic pressure increased, and mean left atrial pressure and pulmonary artery pressure decreased for all heart conditions. Regarding high pump-speed support, the systemic flow, aortic pressure, left atrial pressure, and pulmonary artery pressure returned to the level of the normal heart condition. Based on the test results from the Virtual Mock Loop system, the new left ventricular assist device for transapical insertion may be able to ease the symptoms of patients with various types of heart failure. The Virtual Mock Loop system could be helpful to assess pump performance before in vitro bench testing.

Biventricular assist device (BVAD) implantation is the treatment of choice in patients with severe biventricular heart failure and cardiogenic shock. Our team has developed a miniaturized continuous flow, double-ended centrifugal pump intended for total artificial heart implant (CFTAH). The purpose of this initial in vivo study was to demonstrate that the scaled-down CFTAH (P-CFTAH) can be appropriate for BVAD support. The P-CFTAH was implanted in 4 acute lambs (average weight, 41.5 ± 2.8 kg) through a median sternotomy. The cannulation was performed through the left and right atria, and cannulae length adjustment was performed for atrial and ventricular cannulation. The BVAD system was tested at 3 pump speeds (3000, 4500, and 6000 rpm). The BVAD performed very well for both atrial and ventricular cannulation within the 3000-6000 rpm range. Stable hemodynamics were maintained after implantation of the P-CFTAH. The self-regulating performance of the system in vivo was demonstrated by the left (LAP) and right (RAP) pressure difference (LAP-RAP) falling predominantly within the range of -5 to 10 mm Hg with variation, in addition to in vitro assessment of left and right heart failure conditions. Left and right pump flows and total flow increased as the BVAD speed was increased. This initial in vivo testing of the BVAD system demonstrated satisfactory device performance and self-regulation for biventricular heart failure support over a wide range of conditions. The BVAD system keeps the atrial pressure difference within bounds and maintains acceptable cardiac output over a wide range of hemodynamic conditions., (Copyright © 2020 Elsevier Inc. All rights reserved.)

This study aimed to evaluate a newly designed circulatory mock loop intended to model cardiac and circulatory hemodynamics for mechanical circulatory support device testing. The mock loop was built with dedicated ports suitable for attaching assist devices in various configurations. This biventricular mock loop uses two pneumatic pumps (Abiomed AB5000 ™ , Danvers, MA, USA) driven by a dual-output driver (Thoratec Model 2600, Pleasanton, CA, USA). The drive pressures can be individually modified to simulate a healthy heart and left and/or right heart failure conditions, and variable compliance and fluid volume allow for additional customization. The loop output for a healthy heart was tested at 4.2 L/min with left and right atrial pressures of 1 and 5 mm Hg, respectively; a mean aortic pressure of 93 mm Hg; and pulmonary artery pressure of 17 mm Hg. Under conditions of left heart failure, these values were reduced to 2.1 L/min output, left atrial pressure = 28 mm Hg, right atrial pressure = 3 mm Hg, aortic pressure = 58 mm Hg, and pulmonary artery pressure = 35 mm Hg. Right heart failure resulted in the reverse balance: left atrial pressure = 0 mm Hg, right atrial pressure = 30 mm Hg, aortic pressure = 100 mm Hg, and pulmonary artery pressure = 13 mm Hg with a flow of 3.9 L/min. For biventricular heart failure, flow was decreased to 1.6 L/min, left atrial pressure = 13 mm Hg, right atrial pressure = 13 mm Hg, aortic pressure = 52 mm Hg, and pulmonary artery pressure = 18 mm Hg. This mock loop could become a reliable bench tool to simulate a range of heart failure conditions.

Background: We investigated whether both echocardiography and blood examination parameters obtained before discharge are more closely associated with adverse events than those obtained upon admission in hospitalized heart failure (HF) patients., Methods: We retrospectively selected 267 hospitalized HF patients who underwent comprehensive transthoracic echocardiography (TTE) within 2 days of admission (n=223) and/or within 7 days of discharge (n=157). Blood test results were also collected at the same time window. Patients were assigned into HF with reduced ejection fraction (HFrEF) and HF with preserved EF (HFpEF)., Results: During a median follow-up of 12.6 months, 60 of 223 patients with admission TTE and 39 of 157 patients with pre-discharge TTE had major adverse cardiac events (MACEs) after discharge. On admission, no echocardiography parameters, but uric acid, blood urea nitrogen (BUN), creatinine, and estimated glomerular filtration rate (eGFR) were associated with MACEs in HFpEF (n=45). In HFrEF (n=178), vena contracta, s', BUN, eGFR, and N-terminal pro-B-type natriuretic peptide (NT-proBNP) were associated with MACEs. Before discharge, BNP, NT-proBNP, and E/e' were significantly associated with MACEs in HFpEF (n=41). In HFrEF (n=116), several echocardiography parameters and blood tests were significantly associated with MACEs., Conclusions: Optimal examination timing for prognostication is different between echocardiography but not for blood tests. TTE before discharge provides more information in both HF phenotypes, while blood tests play a role both upon admission and before discharge. Therefore, a pre-discharge TTE was recommended in patients admitted for HF., (Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.)

Background: Exercise-induced pulmonary hypertension (EIPH) may develop even at low workloads in heart failure (HF) patients. Ventricular-arterial stiffening plays an important role in the pathophysiology of HF with preserved ejection fraction (HFpEF). This study aimed to compare the response of ventricular-arterial coupling and PH during low-level exercise between HFpEF and HF with reduced EF (HFrEF)., Methods and Results: Echocardiography was performed at rest and during 10 W of bicycle exercise in HFpEF (n = 37) and HFrEF (n = 43). Load-independent contractility (end-systolic elastance [Ees], preload recruitable stroke work [PRSW], and peak power index [PWRI]), arterial afterload (arterial elastance [Ea]), and ventricular-arterial interaction (Ea/Ees) were measured with the use of a noninvasive single-beat technique. EIPH was defined as an estimated pulmonary arterial systolic pressure (PASP) of ≥50 mm Hg at 10 W of exercise. PASP was significantly increased during 10 W of exercise in both HF types, and ~50% of HFpEF patients developed EIPH. Arterial afterload was increased significantly during exercise in both groups. HFrEF and HFpEF patients showed a significant increase in LV contractility assessed by Ees, PRSW, and PWRI during exercise. Although Ea/Ees ratio decreased significantly in HFrEF, reduction in Ea/Ees was attenuated because of blunted Ees increases in patients with HFpEF compared with HFrEF., Conclusions: Even at low-level exercise, ~50% of HFpEF patients developed EIPH. Reduction in Ea/Ees was attenuated owing to less Ees increase in HFpEF compared with HFrEF. Further studies are needed to elucidate the association between ventricular-arterial coupling and EIPH in HFpEF., (Copyright © 2016 Elsevier Inc. All rights reserved.)

In patients with severe biventricular heart failure (HF) and cardiogenic shock, use of biventricular assist device (BVAD) can be a treatment of choice. We are developing an advanced ventricular assist device (AVAD) intended to serve as universal pump for left and/or right heart failure (Fig.1 A,B). The purpose of this initial in silico simulation study was to demonstrate that AVAD design can be suitable for biventricular support. The virtual mock loop (VML) was developed (MATLAB; MathWorks®) to simulate hemodynamic parameters as they surge through the BVAD-supported systolic HF cardiovascular system. The AVAD used as in BVAD configuration was in 2 speeds (3400 rpm left, 2000 rpm right) to get comparable systemic flow and pressure outputs. LVAD support was adjusted to maintain 5.0 L/min total systemic flow. For BVAD, the added RVAD support was adjusted to maintain left and right atrial pressure (LAP-RAP) at 3-5 mm Hg. The BVAD performance was maintained very well for both left ventricular (L-AVAD) and right ventricular (R-AVAD) support within specified speed range (Fig1 C,D). L- AVAD speed of 3000 - 3500 rpm provided sufficient support for the case of severe left and right systolic heart failure, assuming there was no aortic valve regurgitation. At the simulated condition, with L-AVAD support, the aortic valve remains closed and the systemic pressure has reduced pulse. A stable hemodynamics were maintained. The atrial pressure difference (LAP-RAP) resulted to be sensitive to the right pump speed, though was balanced whenever there was any positive flow through the pulmonary valve. Introduction of R-AVAD support to the L-AVAD support caused the left atrial pressure to increase resulting in increased filling of the left ventricle and a corresponding increase in aortic pulsatility. These initial in silico study demonstrated that use of the universal AVAD as BVAD supports cardiac output and arterial pressure in biventricular HF condition. [ABSTRACT FROM AUTHOR]

Purpose Biventricular assist device (BVAD) implantation is the treatment of choice in patients with severe biventricular heart failure (BHF) and cardiogenic shock. We previously developed a miniaturized continuous flow double-ended centrifugal pump intended for total artificial heart implant (CFTAH). The purpose of this initial in vitro study was to prove that scaled down CFTAH can be suitable for biventricular support. Methods The CFTAH was tested in BVAD configuration at 2 pump speeds (4500 and 6000 rpm) on a pulsatile mock loop with two pneumatic ventricles that simulated normal and heart failure conditions (moderate and severe) by adjusting the systolic and diastolic drive pressures to simulate hemodynamics of the failing biventricular function. Results The BVAD performance was maintained very well for both atrial and ventricular cannulation within the 4500 - 6000 rpm range. A stable hemodynamics were maintained, and the pump's self-regulating performance was confirmed with the most of atrial pressure difference (LAP-RAP) falling within ±5-15 mm Hg in (Mod.) and severe (Sev.) right (RHF) and left HF (LHF) conditions. Left and right pump flows (LPF and RPF) and total flow (TF) increased as the BVAD speed was increased (Figure). The TF was higher than LPF and RPF due to output from the native ventricles, and the LPF was higher than RPF with pump speed of 6,000 rpm, but the TF appeared balanced due to larger native right ventricular output vs. native left ventricle with given condition. Conclusion These initial in vitro study demonstrated that use of the CFTAH as BVAD supports cardiac output and arterial pressure in BHF conditions. In vivo evaluation of this technology is currently pending. [ABSTRACT FROM AUTHOR]