Physical activity based on daily steps in patients with chronic musculoskeletal pain: evolution and associated factors.

BACKGROUND: People with chronic musculoskeletal pain (CMSP) often have low physical activity. Various factors can influence the activity level. The aim of this study was to monitor physical activity, assessed by the number of steps per day, over time in people with CMSP and identify factors that could be associated with this activity feature. METHODS: This prospective study involved people undergoing rehabilitation following an orthopedic trauma that had led to CMSP. At entry, participants completed self-reported questionnaires assessing pain, anxiety, depression, catastrophyzing, kinesiophobia, and behavioural activity patterns (avoidance, pacing and overdoing). They also underwent functional tests, assessing walking endurance and physical fitness. To determine daily step counts, participants wore an accelerometer for 1 week during rehabilitation and 3 months post-rehabilitation. The number of steps per day was compared among three time points: weekend of rehabilitation (an estimate of pre-rehabilitation activity; T1), weekdays of rehabilitation (T2), and post-rehabilitation (T3). Linear regression models were used to analyze the association between daily steps at T2 and at T3 and self-reported and performance-based parameters. RESULTS: Data from 145 participants were analyzed. The mean number of steps was significantly higher during T2 than T1 and T3 (7323 [3047] vs. 4782 [2689], p < 0.001, Cohen's d = 0.769, and 4757 [2680], p < 0.001, Cohen's d = 0.693), whereas T1 and T3 results were similar (p = 0.92, Cohen's d = 0.008). Correlations of number of steps per day among time points were low (r ≤ 0.4). Multivariable regression models revealed an association between daily steps at T2 and pain interfering with walking, anxiety and overdoing behaviour. Daily steps at T3 were associated with overdoing behaviour and physical fitness. CONCLUSIONS: Despite chronic pain, people in rehabilitation after an orthopedic trauma increased their physical activity if they were given incentives to do so. When these incentives disappeared, most people returned to their previous activity levels. A multimodal follow-up approach could include both therapeutic and environmental incentives to help maintain physical activity in this population.

Performance of the Jarvik 2000 left ventricular assist device on mid-term hemodynamics and exercise capacity.

The hemodynamic and exercise capacity performance of the Jarvik 2000 left ventricular assist device (LVAD), which is generally used in patients with small body size and relatively preserved cardiac function, is not well understood. We retrospectively examined 18 patients implanted with the Jarvik 2000 LVAD. Pump rotation speed was optimized by the hemodynamic ramp test one year after implantation based on the criteria of mean pulmonary capillary wedge pressure (PCWP) < 18 mmHg, mean right atrial pressure (RAP) < 12 mmHg, and cardiac index (CI) > 2.2 L/min/m2 as well as echocardiographic parameters. Exercise capacity was assessed by cardiopulmonary exercise test in an optimized setting. To investigate the impacts of larger body surface area (BSA) and extremely impaired pre-implantation cardiac function on hemodynamics and exercise capacity, two correlation analyses based on BSA and original CI were performed. At a pump speed of 9500 ± 707 rpm, the mean pulmonary artery pressure, PCWP, RAP, and CI were 17 ± 5 mmHg, 9 ± 5 mmHg, 6 ± 4 mmHg, and 2.82 ± 0.54 L/min/m2, respectively. Only one patient failed to achieve the hemodynamic criteria. The peak VO2 and VE/VCO2 slope were 12.9 ± 3.1 mL/min/kg and 37.7 ± 15.0, respectively. There was an inverse correlation between original CI and heart rate (r = -0.60, p = 0.01), and a weak correlation between BSA and PCWP (r = 0.43, p = 0.08). Based on this study, the overall performance of the Jarvik 2000 device was acceptable, and the patients' body size and original cardiac function had minimum effect on the performance of this device.

A Novel Method to Measure the Static Coefficient of Friction for Socks.

Mechanical testers have commonly been used to measure the frictional properties of socks. However, the friction values may be susceptible to the level of stretchiness of tested fabrics or human variability. Thus, the aim of this study was to propose a novel method that enables friction measurement of socks in a sock-wearing condition with less human variability effects. Five socks with different frictional properties were chosen. Three experimental ramp tests were performed with an artificial structure shaped like the foot-ankle complex (last) and a ramp tester to quantify the static coefficient of friction (COF) at the foot against sock, at the sock against an insole, and the foot wearing socks against the insole, respectively. The angle where the last slipped while the ramp surface was gradually inclined was used to compute the static COF values for each sock. The reliability was 0.99, and COF values ranged from 0.271 to 0.861 at the foot-sock interface, 0.342 to 0.639 at the sock-insole interface, and 0.310 to 0.614 in the third test. Socks with different frictional properties were successfully distinguished each other. Thus, the suggested protocol could be a reliable option for measuring the static COF values in the tension similar with it found in a sock-waring condition with reduced effects of human variability.

Correlation Between Intraventricular Pressure Difference and Indexed Flow of a Left Ventricular Assist Device.

OBJECTIVES: There is no definitive parameter for left ventricular (LV) preload in patients with a continuous-flow left ventricular assist device (LVAD). The intraventricular pressure difference (IVPD) is the maximum pressure difference between the mitral valve and LV apex during diastole; and, in past studies, the IVPD was influenced by volume loading. The authors hypothesized that IVPD in LVAD patients correlates with indexed LVAD flow and that IVPD can serve as a novel parameter of LV preload in this population. DESIGN: A single-center, retrospective, observational study. SETTING: A tertiary-care hospital from August 2019 to July 2020. PARTICIPANTS: Sixteen ramp tests for adjustment of LVAD pump speed in 14 adult patients undergoing continuous-flow LVAD implantation. INTERVENTIONS: Measurement of IVPD during ramp tests. MEASUREMENTS AND MAIN RESULTS: LVAD flow and IVPD were measured at each LVAD pump speed during the ramp test for the adjustment of LVAD pump speed after patients came off cardiopulmonary bypass during LVAD implantation. A straight, longitudinal view of the left atrium and left ventricle was obtained, and the pressure difference between the mitral valve and LV apex during diastole was measured by transesophageal echocardiography. The maximum pressure difference during diastole was recorded as IVPD. The relationship between indexed LVAD flow (LVAD flow/body surface area) and IVPD was assessed by a multivariate nonlinear regression analysis with the Huber-White sandwich estimator. IVPD correlated with indexed LVAD flow (p < 0.001). CONCLUSIONS: IVPD is a useful indicator of LV preload during LVAD implantation.

A new hemodynamic index to predict late right failure in patients implanted with last generation centrifugal pump.

BACKGROUND: Right ventricular failure (RVF) is a severe event that increases perioperative mortality after left ventricle assist device (LVAD) implantation. Right ventricular (RV) function is particularly affected by the LVAD speed by altering RV preload and afterload as well as the position of the interventricular septum. However, there are no studies focusing on the relationship between pump speed optimization and risk factors for the development of late RVF. METHODS: Between 2015 and 2019, 50 patients received LVAD implantation at San Camillo Hospital in Rome. Of these, 38 who underwent pump speed optimization were included. Post-optimization hemodynamic data were collected. We assessed a new Hemodynamic Index (HI), calculated as follows:  HI = MAP × PCWP CVP × RPM set RPM max , to determine the risk of late RVF, which was defined as the requirement for rehospitalization and inotropic support. RESULTS: Ten patients had late RVF after LVAD implantation. Five patients required diuretic therapy and speed optimization. Three patients required inotropic support with adrenaline 0.05 µg/kg/min. Two patients needed prolonged continuous venovenous hemofiltration and high dose inotropic support. Multivariate analysis revealed that a low HI (odds ratio 11.5, 95% confidence interval, 1.85-65.5, p [.003]) was an independent risk factor for late RVF after LVAD implantation. CONCLUSION: We demonstrated a low HI being a significant risk factor for the development of RVF after LVAD implantation. We suggest implementing HI as a decision support tool for goal-direct optimization of the device aiming to reduce the burden of late-onset RVF during the follow-up.

Echocardiographic Changes in Patients Implanted With a Fully Magnetically Levitated Left Ventricular Assist Device (Heartmate 3).

BACKGROUND: The Heartmate 3 (HM3) is a Conformiteé Européenne mark-approved left ventricular (LV) assist device (LVAD) with fully magnetically levitated rotor and features consisting of a wide range operational speeds, wide flow paths, and artificial pulse. We performed a hemodynamic-echocardiographic speed optimization evaluation in HM3-implanted patients to achieve optimal LV- and right ventricular (RV) shape. METHODS AND RESULTS: Sixteen HM3 patients underwent pump speed ramp tests with right heart catheterization. Three-dimensional echocardiographic (3DE) LV and RV datasets (Philips) were acquired, and volumetric (Tomtec) and shape (custom software) analyses were performed (LV: sphericity, conicity; RV: septal and free-wall curvatures). Data were recorded at up to 13 speed settings. Speed changes were in 100-rpm steps, starting at 4600 rpm and ramping up to 6200 rpm. 3DE was feasible in 50% of the patients. Mean original speed was 5306 ± 148 rpm. LV end-diastolic (ED) diameter (-0.15 ± 0.09 cm/100 rpm) and volumes (ED: 269 ± 109 mL to 175 ± 90 mL; end-systolic [ES]: 234 ± 111 mL to 146 ± 81 mL) progressively decreased as the shape became less spherical and more conical; RV volumes initially remained stable, but at higher speeds increased (ED: from 148 ± 64 mL to 181 ± 92 mL; ES: 113 ± 63 mL to 130 ± 69 mL). On average, the RV septum became less convex (bulging toward the LV) at the highest speeds. CONCLUSIONS: LV and RV shape changes were noted in HM3-supported patients. Although a LV volumetric decrease and shape improvement was consistently noted, RV volumes grew in response to increase in speed above a certain point. A next concern would be whether understanding of morphologic and function changes in LV and RV during LVAD speed change assessed with the use of 3DE helps to optimize LVAD speed settings and improve clinical outcomes.

New Challenges in the Treatment of Patients With Left Ventricular Support: LVAD Thrombosis.

Mechanical circulatory support has revolutionized the treatment of heart failure, affording patients significantly improved survival and quality of life. However, further advancements in this technology have been hindered by adverse events, particularly gastrointestinal bleeding, driveline infection, stroke, and device thrombosis. Recently, there has been a renewed focus on device thrombosis as the reported incidence has increased. This review focuses on an update on the diagnostic modalities and current treatment algorithms of this serious complication.

A Simple Modification to the Mosquito Homogenization Protocol Safely Inactivates West Nile Virus and Allows Virus Detection by the Rapid Analyte Measurement Platform (RAMP®) ASSAY.

We evaluated the ability of the Rapid Analyte Measurement Platform (RAMP(®)) mosquito-grinding buffer to inactivate West Nile virus (WNV) by subjecting WNV-positive samples ground in RAMP buffer to incubation intervals ranging from 5 min to 60 min. At each time point an aliquot was removed and serially diluted in bovine albumin (BA)-1 cell culture media to stop the inactivation process by RAMP buffer. Each BA-1 sample was tested for viable virus using Vero 6-well cell culture plaque assay and observed for plaques. We observed very limited inactivation of WNV (1-2 log10 plaque-forming units/ml) by RAMP buffer. Concerned for RAMP operators who may be using this assay in low-level biocontainment facilities, we developed an alternate sample homogenization protocol using Triton X-100 detergent that ensures complete WNV inactivation without compromising the performance of the RAMP assay.

Individual versus Standardized Running Protocols in the Determination of VO2max.

The purpose of this study was to determine whether an individually designed incremental exercise protocol results in greater rates of oxygen uptake (VO2max) than standardized testing. Fourteen well-trained, male runners performed five incremental protocols in randomized order to measure their VO2max: i) an incremental test (INCS+I) with pre-defined increases in speed (2 min at 8.64 km·h(-1), then a rise of 1.44 km·h(-1) every 30 s up to 14.4 km·h(-1)) and thereafter inclination (0.5° every 30 s); ii) an incremental test (INCI) at constant speed (14.4 km·h(-1)) and increasing inclination (2° every 2 min from the initial 0°); iii) an incremental test (INCS) at constant inclination (0°) and increasing speed (0.5 km·h(-1) every 30 s from the initial 12.0 km·h(-1)); iv) a graded exercise protocol (GXP) at a 1° incline with increasing speed (initially 8.64 km·h(-1) + 1.44 km·h(-1) every 5 min); v) an individual exercise protocol (INDXP) in which the runner chose the inclination and speed. VO2max was lowest (-4.2%) during the GXP (p = 0.01; d = 0.06-0.61) compared to all other tests. The highest rating of perceived exertion, heart rate, ventilation and end-exercise blood lactate concentration were similar between the different protocols (p < 0.05). The time to exhaustion ranged from 7 min 18 sec (INCS) to 25 min 30 sec (GXP) (p = 0.01).The VO2max attained by employing an individual treadmill protocol does not differ from the values derived from various standardized incremental protocols. Key pointsThe mean maximum oxygen uptake during the GXP was lower than for all other tests.Differences in the maximum rate of oxygen uptake between the various protocols exhibited considerable inter-individual variation.From the current findings, it can be concluded that well trained athletes are able to perform an individually designed treadmill running protocol.

HeartMate 3 Snoopy: Noninvasive cardiovascular diagnosis of patients with fully magnetically levitated blood pumps during echocardiographic speed ramp tests and Valsalva maneuvers.

PURPOSE: The HeartMate 3 (HM3) left ventricular assist device (LVAD) has demonstrated excellent clinical outcomes; however, pump speed optimization is challenging with the available HM3 monitoring. Therefore, this study reports on clinical HM3 parameters collected with a noninvasive HM3 monitoring system (HM3 Snoopy) during echocardiographic speed ramp tests and Valsalva maneuvers. METHODS: In this prospective, single-center study, the HM3 data communication between the controller and pump was recorded with a novel data acquisition system. Twelve pump parameters sampled every second (1 Hz) and clinical assessments (echocardiography, electrocardiogram (ECG), and blood pressure measurement) during speed ramp tests were analyzed using Pearson's correlation (r, median [IQR]). The cause for the occurrence of pulsatility index (PI)-events during ramp speed tests and valsalva maneuvers was investigated. RESULTS: In 24 patients (age: 58.9 ± 8.8 years, body mass index: 28.1 ± 5.1 kg/m2, female: 20.8%), 35 speed ramp tests were performed with speed changes in the range of ±1000 rpm from a baseline speed of 5443 ± 244 rpm. Eight HM3 pump parameters from estimated flow, motor current, and LVAD speed together with blood pressure showed positive collinearities (r = 0.9 [0.1]). Negative collinearities were observed for pump flow pulsatility, pulsatility index, rotor noise, and left ventricular diameters (r = -0.8 [0.1]), whereas rotor displacement and heartrate showed absence of collinearities (r = -0.1 [0.08]). CONCLUSIONS: In this study, the HM3 Snoopy was successfully used to acquire more parameters from the HM3 at a higher sampling rate. Analysis of HM3 per-second data provide additional clinical diagnostic information on heart-pump interactions and cause of PI-events.

Arthroscopic diagnosis of long head of biceps tendon instability in refractory anterior shoulder pain: A comparison study between pulley tear and non-tear lesions.

BACKGROUND: Long head of the biceps tendon (LHBT) instability and biceps reflection pulley (BRP) lesions are common cause of refractory anterior shoulder pain. We described a technique using dynamic arthroscopy to determine associated intraarticular pathologies. METHODS: Patients with refractory anterior shoulder pain and arthroscopically-diagnosed LHBT instability were enrolled. LHBT instability and the integrity of BRP and concomitant intra-articular lesions were investigated by ramp test. Demographics and arthroscopic findings were compared between patients with and without BRP tear. RESULTS: Forty patients were enrolled. BRP tear was noted in 25 patients (group A) and superior glenohumeral ligament (SGHL) insufficiency through ramp test in 15 patients (group B). Concomitant intraarticular pathologies were noted in 27 patients, including 19 in group A (76%) and eight in group B (53%), without significant group-wise difference (p = 0.138). The incidence of articular-side subscapularis tear was significantly higher in group A (p = 0.021), and those of the other intraarticular pathologies were similar between groups A and B. Fraying at the articular side of the subscapularis and supraspinatus tendons was frequent in group B, without difference of incidence as compared to group A (p = 0.5 and p = 0.084, respectively). CONCLUSIONS: LHBT instability was a common disorder in patients with refractory shoulder pain. In those patients, dynamic assessment of BRP lesions and SGHL insufficiency and meticulous survey of associated intra-articular pathologies, including subscapularis tear are necessary for making accurate diagnosis and treatment decision.

Development of Saturated Fat Replacers: Conventional and Nano-Emulsions Stabilised by Lecithin and Hydroxylpropyl Methylcellulose.

The combination of two emulsifiers, lecithin and hydroxypropyl methylcellulose (HPMC), into emulsions is an interesting strategy to design fat replacers in food matrices. The objective of this study was to investigate the effect of HPMC type and concentration on the formation, stability, and microstructure of conventional emulsions and nanoemulsions. Two different types of HPMC with low and high content of methyl and hydroxypropyl groups (HPMC-L and HPMC-H) were evaluated. The results showed that the molecular structure and concentration of HPMC play a major role in the viscoelastic behaviour, the gelation temperature, and the strength of gel formed. The firmness and work of shear of HPMC solutions increased significantly (p < 0.05) with increasing concentration. HPMC-L illustrated a more stable gel structure than the HPMC-H solution. Nanoemulsions showed lower moduli values, firmness, and work of shear than conventional emulsions due to the influence of high-pressure homogenization. A combination of lecithin and HPMC improved the physical and lipid oxidative stability of the emulsions, presenting a lower creaming index and thiobarbituric acid reactive substances (TBARS). In conclusion, HPMC-L at 2% w/w could be a suitable type and concentration combined with lecithin to formulate a saturated fat replacer that could mimic butter technological performance during food manufacturing operations.

What Makes a Floor Slippery? A Brief Experimental Study of Ceramic Tiles Slip Resistance Depending on Their Properties and Surface Conditions.

The safety of the use of construction facilities should be a priority in today's busy world, where it is not difficult to get involved in an accident. Most of them, due to the pace at which we live today, are caused by slips, trips, and falls. This work presents a detailed analysis of the resistance of ceramic floors to these events, taking into account the surface properties and conditions (dry/wet), which, as presented, have a significant impact on the final slip resistance values. This study also investigates the relationship between surface roughness and anti-slip properties. According to the obtained results, it can be concluded that the surface roughness is not the main determinant of slip resistance, and the final value of it is influenced by many components that should be considered together and not be neglected when designing the surface finish. Furthermore, based on experimental measurements, it can be noted that the highest slip resistance in both wet and dry conditions showed the unglazed tiles with lapatto finish and the glazed tiles without any extra finish.

Comparative Analysis of Slip Resistance Test Methods for Granite Floors.

This paper attempts to compare three methods of testing floor slip resistance and the resulting classifications. Polished, flamed, brushed, and grained granite slabs were tested. The acceptance angle values (αob) obtained through the shod ramp test, slip resistance value (SRV), and sliding friction coefficient (µ) were compared in terms of the correlation between the series, the precision of each method, and the classification results assigned to each of the three obtained indices. It was found that the evaluation of a product for slip resistance was strongly related to the test method used and the resulting classification method. This influence was particularly pronounced for low roughness slabs. This would result in risks associated with inadequate assessments, which could affect the safe use of buildings facilities.

Validation of non-invasive ramp testing for HeartMate 3.

AIMS: Ramp testing in the postoperative period can be used to optimize left ventricular assist device (LVAD) speed for optimal left ventricular (LV) unloading. We tested the hypothesis that a non-invasive echocardiographic ramp test post-HeartMate 3 implantation improves LV unloading immediately after and 1-3 months after as compared with before the test. We also tested a secondary hypothesis that speed adjustments during echocardiography-guided ramp testing do not worsen right ventricular (RV) function immediately after and 1-3 months after. METHODS AND RESULTS: We retrospectively reviewed data from patients who underwent an echocardiographic ramp test. A total of 14 out of 19 patients were clinically stable and were enrolled. Adequate LV unloading was defined as no more than mild mitral regurgitation, and intermittent aortic valve (AV) opening or closed AV, and reduction of left ventricular end-diastolic diameter (LVEDD); and for the follow-up measurement, decreased NT-proBNP. Median (interquartile range) time from implantation to ramp test was 27 (16; 56) days, and median time from ramp test to follow-up echocardiography was 55 (47; 102) days. Median LVAD speed achieved during ramp testing was 5550 (5375; 6025) revolutions per minute (rpm), and median final LVAD speed was 5200 (5000; 5425) rpm. Ramp testing resulted in final LVAD speed increase in 11 (79%) patients and a median net change of 200 (200; 300) rpm. Speed adjustments after ramp testing resulted in improved LVAD unloading that was achieved in additional 3 (21%) patients who were not originally optimized. RV function did not worsen significantly during ramp testing or at final LVAD speed. CONCLUSIONS: The echocardiographic ramp test allowed LVAD speed adjustment and optimization and improved LV unloading during ramp testing and at final speed with no evidence of worsening of RV function.

Concentric and Eccentric Pedaling-Type Interval Exercise on a Soft Robot for Stable Coronary Artery Disease Patients: Toward a Personalized Protocol.

BACKGROUND: Cardiovascular diseases are the leading causes of death worldwide, and coronary artery disease (CAD) is one of the most common causes of death in Europe. Leading cardiac societies recommend exercise as an integral part of cardiovascular rehabilitation because it reduces the morbidity and mortality of patients with CAD. Continuous low-intensity exercise using shortening muscle actions (concentric, CON) is a common training modality during cardiovascular rehabilitation. However, a growing clinical interest has been recently developed in high-intensity interval training (HIIT) for stable patients with CAD. Exercise performed with lengthening muscle actions (eccentric, ECC) could be tolerated better by patients with CAD as they can be performed with higher loads and lower metabolic cost than CON exercise. OBJECTIVE: We developed a clinical protocol on a soft robot to compare cardiovascular and muscle effects of repeated and work-matched CON versus ECC pedaling-type interval exercise between patients with CAD during cardiovascular rehabilitation. This study aims to ascertain whether the developed training protocols affect peak oxygen uptake (VO2peak), peak aerobic power output (Ppeak), and parameters of muscle oxygen saturation (SmO2) during exercise, and anaerobic muscle power. METHODS: We will randomize 20-30 subjects to either the CON or ECC group. Both groups will perform a ramp test to exhaustion before and after the training period to measure cardiovascular parameters and SmO2. Moreover, the aerobic skeletal muscle power (Ppeak) is measured weekly during the 8-week training period using a simulated squat jump and a counter movement jump on the soft robot and used to adjust the training load. The pedaling-type interval exercise on the soft robot is performed involving either CON or ECC muscle actions. The soft robotic device being used is a closed kinetic chain, force-controlled interactive training, and testing device for the lower extremities, which consists of two independent pedals and free footplates that are operated by pneumatic artificial muscles. RESULTS: The first patients with CAD, who completed the training, showed protocol-specific improvements, reflecting, in part, the lower aerobic training status of the patient completing the CON protocol. Rehabilitation under the CON protocol, more than under the ECC protocol, improved cardiovascular parameters, that is, VO2peak (+26% vs -6%), and Ppeak (+20% vs 0%), and exaggerated muscle deoxygenation during the ramp test (248% vs 49%). Conversely, markers of metabolic stress and recovery from the exhaustive ramp test improved more after the ECC than the CON protocol, that is, peak blood lactate (-9% vs +20%) and peak SmO2 (+7% vs -7%). Anaerobic muscle power only improved after the CON protocol (+18% vs -15%). CONCLUSIONS: This study indicates the potential of the implemented CON and ECC protocols of pedaling-type interval exercise to improve oxygen metabolism of exercised muscle groups while maintaining or even increasing the Ppeak. The ECC training protocol seemingly provided a lower cardiovascular stimulus in patients with CAD while specifically enhancing the reoxygenation and blood lactate clearance in recruited muscle groups during recovery from exercise. TRIAL REGISTRATION: ClinicalTrials.gov NCT02845063; https://clinicaltrials.gov/ct2/show/NCT02845063.

Reproducibility of peak oxygen consumption and the impact of test variability on classification of individual training responses in young recreationally active adults.

This study investigated whether VO2 peak is reproducible across repeated tests before (PRE) and after (POST) training, and whether variability across tests impacts how individual responses are classified following 3 weeks of aerobic exercise training (cycle ergometry). Data from 45 young healthy adults (age: 20·1 ± 0·9 years; VO2 peak, 42·0 ± 6·7 ml·min-1 ) from two previously published studies were utilized in the current analysis. Non-responders were classified as individuals who failed to demonstrate an increase or decrease in VO2 peak that was greater than 2·0 times the typical error of measurement (107 ml·min-1 ) away from zero, while responders and adverse responders were above and below this cut-off, respectively. VO2 peak tests at PRE (three total) and POST (three total) were highly reproducible (PRE and POST average and single measures ICCs: range 0·938-0·992), with low coefficients of variation (PRE:4·9 ± 3·1%, POST: 4·8 ± 2·7%). However, a potential learning effect was observed in the VO2 peak tests prior to training, as the initial pretraining test was significantly lower than the third (p = 0·010, PRE 1: 2 946 ± 924 ml·min-1 , PRE 3: 3 042 ± 919 ml·min-1 ). This resulted in fewer individuals classified as adverse responders for Test 3 compared to any combination of tests that included Test 1, suggesting that a single ramp test at baseline may not be sufficient to accurately classify the VO2 peak response in young recreationally active individuals. Thus, it is our recommendation that the initial VO2 peak test be used as a familiarization visit and not included for analysis.

Clinical hemodynamic evaluation of patients implanted with a fully magnetically levitated left ventricular assist device (HeartMate 3).

BACKGROUND: The HeartMate 3 (HM3) is a Conformiteé Européenne (CE) mark-approved left ventricular assist device (LVAD) with a fully magnetically levitated rotor with features consisting of a wide range of operational speeds, wide flow paths and an artificial pulse. We performed a hemodynamic and echocardiographic evaluation of patients implanted with the HM3 LVAD to assess the speed range for optimal hemodynamic support. METHODS: Sixteen HM3 patients underwent pump speed ramp tests with right heart catheterization (including central venous pressure [CVP], pulmonary artery pressure, pulmonary capillary wedge pressure [PCWP] and blood pressure [BP]) and 3-dimensional echocardiography (3DE). Data were recorded at up to 13 speed settings. Speed changes were in steps of 100 revolutions per minute (rpm), starting at 4,600 rpm and ramping up to 6,200 rpm. RESULTS: Mean original speed was 5,306 ± 148 rpm, with a majority of patients (10 of 16, 62.5%) having normal CVPs and PCWPs at their original rpm settings. Going from lowest to highest speeds, cardiac output improved at the rate of 0.08 ± 0.08 liter/min per 100 rpm (total change 1.25 ± 1.20 liters/min) and PCWP decreased at the rate of -0.48 ± 0.27 mm Hg per 100 rpm (total change -6.13 ± 3.72 mm Hg). CVP and systolic BP did not change significantly with changes in rpm. Left ventricular end-diastolic dimension (LVEDD) decreased at a rate of -0.15 ± 0.09 cm per 100 rpm. Number of rpm was adjusted based on test results to achieve CVPs and PCWPs as close to normal limits as possible, which was feasible in 13 (81.3%) patients. For the remaining 3 patients, medical management was pursued to optimize hemodynamic support. CONCLUSION: Hemodynamic normalization of pressures was achieved in the majority of patients implanted with the HM3 pump within a narrow speed range.

Echocardiographic Ramp test for continuous-flow left ventricular assist devices: do loading conditions matter?

OBJECTIVES: This study investigated whether continuous AI and/or elevated mean arterial pressure (MAP) were associated with false positive results for flow obstruction in echocardiographic ramp speed tests in patients with a continuous-flow left ventricular assist device. BACKGROUND: Failure to reduce the left ventricular end-diastolic diameter (LVEDD) with increasing device speeds in a ramp test is predictive of pump obstruction. Aortic insufficiency (AI) or increased MAP can diminish the ability to unload the left ventricle. METHODS: LVEDD was plotted against device speed, and a linear function slope was calculated. A flat LVEDD slope (≥-0.16) was considered abnormal (suggestive of obstruction). Ramp test results were compared in patients with or without either AI or increased MAP at baseline speed, and receiver-operator characteristic (ROC) curves were constructed for predictors of device obstruction. Device thrombosis was confirmed by direct visualization of clot at explantation or on inspection by the manufacturer. RESULTS: Of 78 ramp tests (55 patients), 36 were abnormal (18 true positive, 18 false positive), and 42 were normal (37 true negative, 5 false negative). In patients with AI, LVEDD slope was -0.14 ± 0.17, which was consistent with device obstruction (vs. -0.25 ± 0.11 in patients without AI; p < 0.001), despite no difference in mean lactate dehydrogenase concentration between the 2 groups (1,301 ± 1,651 U/l vs. 1,354 ± 1,365 U/l; p = 0.91). Area under the ROC curve (AUC) for LVEDD slope was 0.76 and improved to 0.88 after removal of patients with AI from the study. LVEDD slope in patients with MAP ≥85 mm Hg was similar to that for device obstruction (-0.18 ± 0.07) and was abnormal in 6 of the 12 ramp tests performed. Combining LVEDD slope with lactate dehydrogenase concentration increased the AUC to 0.96 as an indicator of device obstruction. CONCLUSIONS: Abnormal loading conditions due to AI or elevated MAP may result in false positive ramp tests.