Myocardial hemodynamics, physiology, and perfusion with an axial flow left ventricular assist device in the calf

The Jarvik 2000 axial flow left ventricular assist device (LVAD) is used clinically as a bridge to transplantation or as destination therapy in end-stage heart disease. The effect of the pump's continuous flow output on myocardial and end-organ blood flow has not been studied experimentally. To address this, the Jarvik 2000 pump was implanted in eight calves and then operated at speeds ranging from 8,000 to 12,000 rpm. Micromanometry, echocardiography, and blood oxygenation measurements were used to assess changes in hemodynamics, cardiac dimensions, and myocardial metabolism, respectively, at different speeds as compared with baseline (pump off, 0 rpm) in this experimental model. Microsphere studies were performed to assess the effects on heart, kidney, and brain perfusion at different speeds. The Jarvik 2000 pump unloaded the left ventricle and reduced end-diastolic pressures and left ventricular dimensions, particularly at higher pump speeds. The ratio of myocardial oxygen consumption to coronary blood flow and the ratio of subendocardial to subepicardial blood flow remained constant. Optimal adjustment of pump speed and volume status allowed opening of the aortic valve and contribution of the native left ventricle to cardiac output, even at the maximum pump speed. Neither brain nor kidney microcirculation was adversely affected at any pump speed. We conclude that the Jarvik 2000 pump adequately unloads the left ventricle without compromising myocardial metabolism or end-organ perfusion.     

The enabler cannula pump: a novel circulatory support system.

BACKGROUND: The enabler circulatory support system is a catheter pump which expels blood from the left or right ventricular cavity and provides pulsatile flow in the ascending aorta or pulmonary artery. It is driven by a bedside installed pulsatile driving console. The device can easily be implanted by a minimal invasive approach, similar to the Hemopump. PURPOSE: To demonstrate the hemodynamic performance of this new intracardiac support system. METHODS: In a series of 9 sheep, hemodynamic evolutions were recorded in various conditions of myocardial contractility (the non-failing, the moderately failing and the severely failing heart). Heart failure was induced by injection of microspheres in the coronary arteries. RESULTS: Introduction of the cannula through the aortic valve was feasible in all cases. Pump flow by the enabler was gradually increased to a maximum of 3.5 L/min. Diastolic (and mean) aortic blood pressure is significantly increased in the non-failing and moderately failing condition (counterpulsation mode). In heart failure, cardiac output is significantly increased by the pump (p < 0.0001). A drop in left atrial pressure (indicating unloading) is achieved in all conditions but reaches significant levels only during heart failure (p=0.0068). CONCLUSIONS: This new circulatory support system contributes to stabilization of the circulation in the presence of cardiac unloading. In heart failure it actually supports the circulation by increasing cardiac output and perfusion pressure.     

Measurement of hemodynamic changes with the axial flow blood pump installed in descending aorta

We have developed various axial flow blood pumps to realize the concept of the Valvo pump, and we have studied hemodynamic changes under cardiac assistance using an axial flow blood pump in series with the natural heart. In this study, we measured hemodynamic changes of not only systemic circulation but also cerebral circulation and coronary circulation under cardiac support using our latest axial flow blood pump placed in the descending aorta in an acute animal experiment. The axial flow blood pump was installed at the thoracic descending aorta through a left thoracotomy of a goat (43.8 kg, female). When the pump was on, the aortic pressure and aortic flow downstream of the pump increased with preservation of pulsatilities. The pressure drop upstream of the pump caused reduction of afterload pressure, and it may lead to reduction of left ventricular wall stress. However, cerebral blood flow and coronary blood flow were decreased when the pump was on. The axial flow blood pump enables more effective blood perfusion into systemic circulation, but it has the potential risk of blood perfusion disturbance into cerebral circulation and coronary circulation. The results indicate that the position before the coronary ostia might be suitable for implantation of the axial flow blood pump in series with the natural heart to avoid blood perfusion disturbances.     

Treatment of multiple organ failure by a totally implantable ventricular assist device

Multiple organ failure (MOF) becomes an important problem during clinical use of the ventricular assist device (VAD). To improve the clinical record of the VAD, the function of other organs may be vitally important. For that reason, we have been developing a VAD system aiming at improving the function of other organs. Development of the vibrating flow pump (VFP), which can generate a unique flow pattern from 10 to 50Hz, is still ongoing in our institute. In order to evaluate brain blood flow and oxygen consumption, oxyhemoglobin was measured with NIRO (Hamamatsu Photo.) in healthy adult goats. Four healthy adult goats were anesthetized with halothane inhalation, and left thoracotomy was performed for left heart bypass. Oxyhemoglobin in the brain was measured with the recording of the hemodynamic variables during left heart assistance with the VFP system. During left heart bypass with the VFP system, the hemodynamic parameters kept within the normal range, and satisfactory pump output was easily obtained. Pump output was kept within 40%–50% bypass to evaluate the effect of high-frequency oscillating assist flow on brain blood flow with the same cardiac output. Interesting results were observed during the experiments. During 30Hz driving of the VFP left heart assistance, oxyhemoglobin suggested that brain blood flow was significantly increased compared with another drive frequency with the same total cardiac output. These results suggest that we can control brain blood flow with a totally implantable VAD system such as the VFP system, which can control the frequency of the blood flow. Presented in part at the 7th Congress of the International Society for Rotary Blood Pumps, August 26–28, 2000, in Tokyo, Japan     

A novel counterpulsation mode of rotary left ventricular assist devices can enhance myocardial perfusion

The effect of rotary left ventricular assist devices (LVADs) on myocardial perfusion has yet to be clearly elucidated, and several studies have shown decreased coronary flow under rotary LVAD support. We have developed a novel pump controller that can change its rotational speed (RS) in synchronization with the native cardiac cycle. The aim of our study was to evaluate the effect of counterpulse mode, which increases the RS in diastole, during coronary perfusion. Experiments were performed on ten adult goats. The EVAHEART LVAD was installed by the left ventricular uptake and the descending aortic return. Ascending aortic flow, pump flow, and coronary flow of the left main trunk were monitored. Coronary flow was compared under four conditions: circuit-clamp, continuous mode (constant pump speed), counterpulse mode (increased pump speed in diastole), and copulse mode (increased pump speed in systole). There were no significant baseline changes between these groups. In counterpulse mode, coronary flow increased significantly compared with that in continuous mode. The waveform analysis clearly revealed that counterpulse mode mainly resulted in increased diastolic coronary flow. In conclusion, counterpulse mode of rotary LVADs can enhance myocardial perfusion. This novel drive mode can provide great benefits to the patients with end-stage heart failure, especially those with ischemic etiology.     

Hydrodynamic properties of a new percutaneous intra-aortic axial flow pump

Cardiac intervention, myocardial infarction, or postoperative heart failure will sometimes create a need for circulatory support. For this purpose, a new, minimally invasive intra-aortic cardiac support system with a foldable propeller has been developed. In animals, the pump has been shown to have a positive hemodynamic influence, and the present study evaluates the hydraulic properties of the pump in a bench test. The axial flow pump is a catheter system with a distal motor driven foldable propeller (0-15,000 revolutions per minute). To protect the aortic wall, filaments forming a cage surround the propeller. In the present study, tests were done with two different pumps, one with and one without the cage. Two different models were used, one for testing pressure generation and one for obtaining flow-pressure characteristics. Propellers and tubes with different diameters were studied, and pressure and flow characteristics were measured. The mathematical relationships between pressure and rotational speed, pressure, and diameter of propeller and tube were determined. There was a positive relationship between the revolutions per minute and the generated pressure, a positive relationship between the diameter of the propeller and pressure, and a negative relationship between the diameter of the tube and the generated pressure. Within the physiologic range of cardiac output, there was a small drop in pressure with increasing flow in the tubes with a small diameter. With an increasing diameter of the tube, a smaller pressure drop was seen with increasing flow. The present cardiac support system has hydraulic properties, which may be of clinical relevance for patients with left ventricular heart failure.     

轴流泵式全人工心脏的体外测试及对负荷反应特性

目的 在体外模拟循环台测试轴流泵式全人工心脏的基本负荷反应特性，为探索生理性控制方案提供基础。方法 轴流泵式全人工心脏样机采用2个轴流泵共同设置在刚性外壳中，直径65 mm，长度70 mm。于模拟循环台上串联连接组成全人工心脏的2个轴流泵，在外周动脉和肺动脉阻力不变的条件下观测前、后负荷变化对心脏输出量的影响。结果 在前负荷固定不变的条件下，增加后负荷时心脏输出流量逐步下降，增大泵转速可对抗后负荷对输出量的抑制，泵转速设定为右心泵8 500 r/min、左心泵11 000 r/min时，心脏输出压力为13.3 kPa（100 mmHg）和输出量6 L/min。当后负荷增大到26.7 kPa（200 mmHg）时心输出量下降为0 L/min。在后负荷固定不变的条件下，前负荷的增加不导致心脏输出量明显改变。设定左心泵转速为11 000 r/min、右心泵转速8 500 r/min时前负荷由0.27 kPa（2 mmHg）增加到1.87 kPa（14 mmHg），流量基本维持在7 L/min。结论 轴流泵式全人工心脏对后负荷增加表现出明显的流量抑制趋势，此趋势可通过调节泵转速改善。轴流泵式全人工心脏对前负荷反应不明显，有别于自然心脏，其机制及调节意义尚待进一步研究。     

Initial acute in vivo performance of the Cleveland Clinic PediPump left ventricular assist device

The PediPump is a small ventricular assist device (VAD) with a hydraulic output range designed to support children from newborns to adolescents. The present report describes our initial evaluation of the PediPump as a left VAD in an acute sheep model. The PediPump was implanted in two sheep (50.8 and 62.7 kg). Pump speed was adjusted to achieve a flow of 2 L/min with the naturally occurring preload and afterload conditions to evaluate pump performance under a steady hemodynamic state for 4 hours. Upon completion, pump performance was evaluated under various blood pressure and heart rate conditions. During steady-state evaluations, the ascending aortic flow and pump speed varied slightly depending on systemic arterial pressure variations. During the hemodynamic manipulation studies, flows ranged between 0.5 and 3.2 L/min with pump speeds of 5,200-16,200 rpm and motor current of 0.06-0.75 A. The PediPump demonstrated good initial hemodynamic performance for use as an implantable left VAD. However, some depositions were detected at the time of explanation, mainly at the rear of the pump. We are continuing with further acute studies to evaluate pump performance in anticipation of beginning chronic studies to evaluate long-term biocompatibility.     

Biventricular support with the Jarvik 2000 ventricular assist device in a calf model of pulmonary hypertension

The Jarvik 2000 ventricular assist device (VAD) is clinically efficacious for treating end-stage left ventricular failure. Because simultaneous right ventricular support is also occasionally necessary, we developed a biventricular Jarvik 2000 technique and tested it in a calf model. One VAD was implanted in the left ventricle with outflow-graft anastomosis to the descending aorta. The other VAD was implanted in the right ventricle with outflow-graft anastomosis to the pulmonary artery. Throughout the 30 day study, hemodynamic values were continuously monitored. On day 30, both pumps were evaluated at different speeds, under various hemodynamic conditions. By gradually occluding the pulmonary artery proximally or distally, we simulated varying degrees of high pulmonary vascular resistance, right ventricular hypertension, global heart failure, or ventricular fibrillation. The two VADs maintained biventricular support even during pulmonary artery occlusion and ventricular fibrillation, yielding a cardiac output of 3-11 L/min, left ventricular end-diastolic pressure of 11-24 mm Hg, and central venous pressure of 9-25 mm Hg. End-organ function was unimpaired, and no major adverse events occurred. The dual VADs offered safe, effective biventricular assistance in the calf. Additional studies are needed to assess the effects of lowered pulse pressure upon the pulmonary circulation and to develop a single pump speed controller.     

Effect of prophylactic digitalization on the development of myocardial hypertrophy.

The effect of prophylactic digitalization on the development of left ventricular hypertrophy was studied in adult rats. Digitoxin, 0.1 mg/100 g body wt or solvent was given daily for 1 wk prior to either aortic constriction or sham operation and was continued until the animals were killed, either 1 or 4 wk after surgery. A hemodynamic study was done in those animals killed 1 wk after surgery; hearts of all animals were examined for evidence of myocardial hypertrophy. Constriction of the ascending aorta had no significant effect on cardiac output but did reduce peak flow velocity and flow acceleration. An increase in left ventricular mass, RNA, and hydroxyproline was found in the animals with aortic constriction. Digitoxin treatment did not alter peak flow velocity or flow acceleration, but did significantly increase isovolumic (dP/dt)P-1. Digitoxin had no effect on body weight, heart weight, RNA, or hydroxyproline in either the sham-operated animals or in the animals with aortic constriction. Therefore, despite plasma digitoxin levels sufficient to affect myocardial contractility, left ventricular hypertrophy still developed after aortic constriction.     

Temporary mechanical circulatory support for severe cardiac failure: experimental study

We describe a technique for mechanical cardiac assistance in an acute model of severe cardiac failure. Cardiac dysfunction was induced by a high dose of halothane in 13 dogs. Seven served as controls. Following median sternotomy, a pneumatically driven device was implanted in the other six dogs in a para-aortic position, using a simple surgical technique without cardiopulmonary bypass. The aorta was cross-clamped during cardiac assistance. During hemodynamic studies, the seven control animals with induced cardiac failure showed high end-diastolic left ventricular and right atrial pressures with low cardiac index and systolic left ventricular and aortic pressures. All dogs in this group died within 30 minutes. Use of a monovalvular cardiac assist device in the experimental group of six dogs to pump blood from the aortic root to the descending aorta in a counterpulsation manner, confirmed good preservation of systemic hemodynamic parameters after induction of heart failure. All animals in this treated group survived more than 45 minutes. Hemodynamically, the device acts as a new ventricle and the impaired left ventricle functionally becomes a left atrium. This condition is clinically appropriate for recovery of left ventricular function in severe acute myocardial failure.     

The heart-pump interaction: effects of a microaxial blood pump

BACKGROUND: When we use rotary blood pumps as an assist device, an interaction takes place between the pump performance and the native heart function (native heart influences pump performance and vice versa). The interaction between native heart and rotary blood pump can be useful to predict recovery of the failing heart. METHODS: The rotary blood pumps used were microaxial catheter-mounted pumps with an external diameter of 6.4 mm (Impella, Aachen, Germany). The pump-heart interaction was studied in five juvenile sheep with a mean body weight of 68.5 +/- 8.7 kg. The pumps were introduced via the left carotid artery and placed in transvalvular aortic position. Recorded parameters were pump speed (rpm), generated flow (L/min) and differential pressure (mm Hg) obtained at high frequency rate of data recordings (25 sets of data per second). This allowed continuous analysis of the pump performance during cardiac cycle. Under clinical conditions the interaction was studied in a 60-year-old male, in whom the device was applied due to postcardiotomy heart failure after myocardial infarction. RESULTS: Heart-pump interaction was analyzed based on pump flow differential pressure. This relationship, analyzed continuously during cardiac cycle, presents as a loop. The dynamic contribution of the heart to the flow generated by the pump leads to continuous fluctuation in the pressure head and the creation of hysteresis. The improved function of the failing heart under clinical conditions after seven days of mechanical support was expressed by: increased hysteresis of the loop caused by increased gradient of flow generated during cardiac cycle, a more pronounced venticular ejection phase that indicates more dynamic heart contribution to the generated flow, and finally increased gradient of the differential pressure during cardiac cycle, caused predominantly by increased aortic pressure and decreased left ventricle pressure during diastolic phase. CONCLUSIONS: The heart-pump interaction based on the pump flow-differential pressure relationship can be useful in predicting the possibility to wean the patient from the device.     

完全磁悬浮心室辅助装置的体外模拟循环系统实验研究

目的研究我国自主研发的第3代完全磁悬浮心室辅助装置(CH-VAD)对于心衰患者的循环辅助效果。方法建立一套体外模拟循环系统(mock circulatory system,MCS)。该系统能够模拟人体健康休息状态以及心力衰竭状态,并与CH-VAD协同工作,测试CH-VAD在连续流状态下的辅助效果。另外,对CH-VAD的搏动流控制方法进行测试,该模式采用正弦波速度波形,使CH-VAD的运行与MCS心室周期同步。结果 CH-VAD在正常连续流状态下能够使心衰状态的血流动力学参数(动脉压、心排量)恢复到正常范围。初步的搏动流测试结果显示,当前的速度搏动幅值对血流动力学影响较小,搏动流状态下与连续流状态所对应的平均动脉压、动脉脉压、平均心排量与心排量波形等差异不大。结论 CH-VAD能够通过搏动控制器产生一定程度的速度搏动,提供足够的心室辅助,并可以进一步改良优化,提供符合生理条件的搏动血流。所研制的MCS能够提供心室辅助装置以及其他机械循环辅助装置一个有效、可控的体外测试平台,是机械循环辅助装置设计、优化和验证的重要工具。     

Non-invasive assessment of cardiac function

Noninvasive assessment of cardiac function by Doppler echocardiography is reviewed. The heart propels the blood through the repeated sequence of systole and diastole. The systolic function is essential to maintain the biological function of the whole body. However, before the heart ejects the blood during systole, the heart must be filled up with blood during the preceding diastole. Thus, the diastolic function is as important as the systolic function. Although the diastolic function is traditionally assessed by hemodynamic parameters obtained in the cardiac catheterization laboratory, it has routinely been assessed by Doppler echocardiography in the echocardiographic laboratory in recent years. Since the concept of diastolic failure has widely spread, the important role of the transmitral flow in assessing the diastolic function has been well recognized. Besides the transmitral flow, the modalities for clinical assessment of the left ventricular diastolic function have been well developed. For example, the pulmonary venous flow has been easily obtained by a transthoracic approach, and the tissue Doppler technique provides important information about the diastolic function, and furthermore the color M-mode is applied for the flow propagation velocity of the left ventricular inflow. These modalities make it possible to assess the left ventricular diastolic function more precisely by Doppler echocardiography. Also, TEI index, strain rate and strain imaging, and wave intensity are mentioned.     

Computer and physical modeling of blood circulation pump support for a new field of application in palliative surgery

OBJECTIVES: One of the most popular palliative procedures performed to increase pulmonary blood flow in children with congenital heart defects is a shunt operation (Blalock-Taussig graft or Glenn procedure), which creates the new blood channel to the pulmonary artery. The main problem with this kind of surgery is poor shunt effectiveness and the lack of possibility to regulate the flow. The aim of this work is to use advanced computer simulation methods to study the effectiveness of a new idea to introduce a small axial blood pump into a Blalock-Taussig (B-T) or Glenn shunt in order to control the blood flow and prevent any increase in the graft stenosis. METHODS: Physical and computer 3-D simulation based on a finite element mesh (FEM) model was applied. Studies for optimization of the shunt and hybrid shunt with pump were performed for different stages of the disease. RESULTS AND CONCLUSION: The graft with the axial pump creates good conditions for the vascular system and pulmonary artery blood flow as well as regulating blood pressure under variable conditions caused by palliative procedures. Its use permits the afterload of the left heart ventricle to be decreased. A palliative procedure is only a temporary solution. When a child grows, while the graft size is fixed, the blood flow through this graft may be not sufficient under changing hemodynamic conditions. The use of an axial pump for regulating the blood flow volume, during palliative procedures, allows to obtain the optimal flow conditions in pulmonary artery and safely wait on the final cardiac surgery correction later. However, the use of a pump mounted inside the graft increased hemodynamic resistance, which caused the flow to decrease up to 70% in the graft when the axial pump was not working.     

Application of extremum seeking control to turbodynamic blood pumps

Ventricular assist devices now clinically used for treatment of end-stage heart failure require responsive and reliable control to accommodate the continually changing demands of the body. However, due to the varying physiologic conditions and the limited use of the sensors to detect hemodynamic load and suction, it is difficult to control pump speed appropriately. The author introduces an adaptive pump speed controller to provide maximum cardiac perfusion while avoiding ventricular suction. The controller is based on an extremum seeking control (ESC) algorithm and a slope seeking control (SSC) algorithm, which find and track unknown and moving peak points of a prescribed cost function. The controller was validated with in vivo data using time-averaged diastolic pump flow as the cost function for ESC/SSC. Initial results demonstrate the successful application of ESC/SSC as a physiologic pump speed controller.     

The effect of aortic valve incompetence on the hemodynamics of a continuous flow ventricular assist device in a mock circulation

There is evidence that the incidence of aortic valve incompetence (AI) and other valvular pathologies may increase as more patients are submitted to longer periods of ventricular assist device (VAD) support. There is a need to better understand the mechanisms associated with the onset of these conditions and other possible complications related to the altered hemodynamics of VAD patients. In this study, the effect of AI on the hemodynamic response of continuous flow VAD (C-VAD) patients was measured in a mock loop over a range of pump speeds and level of native cardiac function. Our results showed that, in the presence of sufficient ventricular function, decreasing the C-VAD speed can allow a transition from series to parallel flow. Our study demonstrated that AI reduces the aortic pressure and flow when system impedance is unchanged. AI produces wasteful recirculation that substantially increases the pump work and decreases systemic perfusion, in particular during series flow conditions coupled with higher C-VAD speeds. The hematologic consequence of this regurgitant flow is a much higher exposure to shear for the blood, increasing the likelihood of hemolysis and thrombosis. While a certain degree of AI can be tolerated by a heart with good cardiac function, the consequences of AI for patients with VADs and poor cardiac function are much greater. Valve dysfunction in VAD patients may be related to structural changes in the tissue induced by altered biomechanics and excessive stress.     

Differential hemodynamic effects of beta-adrenoceptor blockers, Ca antagonists and combined alpha-beta-receptor blockade in ischemic heart disease

The hemodynamic responses to 3 different therapeutical regimens: beta-adrenoceptor blockade, calcium inflow inhibition and combined alpha-beta-blockade were evaluated in 3 matched randomized groups of patients with ischemic heart disease and typical exercise-induced angina. The groups consisted of 22, 16 and 15 men, mean age 55-59 years. They were studied at rest and during ischemia-inducing exercise, before and after single oral doses of 100 mg metoprolol, 10 mg nifedipine and 200 mg labetalol. Pressures in the brachial artery and the pulmonary circulation were recorded by means of percutaneously introduced catheters. Cardiac output was determined according to the Fick principle. Metoprolol reduced mean arterial pressures, heart rate and cardiac output. Systemic vascular resistance and left ventricular filling pressure increased. Nifedipine resulted under all conditions in a distinct reduction of systemic vascular resistance and arterial pressures and a slight increase in heart rate and cardiac output. Left ventricular filling pressure was significantly lowered, the more the higher the initial level. The effect of labetalol was similar to that of nifedipine; however, cardiac output was unchanged and heart rate was slightly reduced. Left ventricular filling pressure was significantly lower. It is apparent that suppression of adrenergic stimulation by beta-receptor blockade alone may have adverse hemodynamic effects in ischemic heart disease and prompt further functional deterioration. Conversely, both calcium and combined alpha-beta-receptor blockade tend to improve left ventricular function by lowering both left ventricular preload and total systemic vascular resistance. The results strongly suggest that in patients in whom beta-receptor blockers appear indicated, their adverse hemodynamic effects can be offset by concomitant alpha1-receptor blockade or vasodilation without losing symptomatic efficacy. Combined alpha-beta-receptor blockade has the advantage over calcium antagonists alone to prevent any increase in adrenergic activity and related hyperkinetic response.     

Arterial pulsatility improvement in a feedback-controlled continuous flow left ventricular assist device: An ex-vivo experimental study

Continuous flow left ventricular assist devices (CF-LVADs) reduce arterial pulsatility, which may cause long-term complications in the cardiovascular system. The aim of this study is to improve the pulsatility by driving a CF-LVAD at a varying speed, synchronous with the cardiac cycle in an ex-vivo experiment. A Micromed DeBakey pump was used as CF-LVAD. The heart was paced at 140 bpm to obtain a constant cardiac cycle for each heartbeat. First, the CF-LVAD was operated at a constant speed. At varying-speed CF-LVAD assistance, the pump was driven such that the same mean pump output was generated. For synchronization purposes, an algorithm was developed to trigger the CF-LVAD each heartbeat. The pump flow rate was selected as the control variable and a reference model was used for regulating the CF-LVAD speed. Continuous and varying-speed CF-LVAD assistance provided the same mean arterial pressure and flow rate, while the index of pulsatility doubled in both arterial pressure and pump flow rate signals under pulsatile pump speed support. This study shows the possibility of improving the pulsatility in CF-LVAD support by regulating pump speed over a cardiac cycle without compromising the overall level of support.     

Derived and displayed power consumption, flow, and pulsatility over a range of HeartMate II left ventricular assist device settings

Continuous-flow left ventricular assist devices/systems (LVADs/LVASs) reduce symptoms and mortality in severe heart failure. The impeller or centrifugal designs provide challenges in assessing and titrating pump speed (revolutions per minute [RPM]), flow, and native heart pulsatility, and contribution to cardiac output. The Thoratec HeartMate II (HM II) LVAS is the most commonly used LVAD worldwide. The user sets the RPM and the monitor provides online data on RPM, power consumption, flow, and pulsatility. These parameters are routinely used by clinicians to assess native heart function and to optimize pump settings. However, little is known about their reliability, reproducibility, and variability. Therefore, we assessed HM II controller parameters and concurrent echocardiography during titrations of RPM to low and high values. We found that data displayed on the monitor and logged in the controller are consistent for power consumption and for flow at settings above 8,000 RPM but inconsistent and unreliable for flow at or below 8,000 RPM and for pulsatility throughout a range of common settings and specifically at 9,000 RPM. These findings have implications for clinicians attempting to optimize settings and assess pump and native heart function.