Exercise in heart failure patients supported with a left ventricular assist device

HeartWare Left Ventricular Assist Device Exercise Hemodynamics With Speed Adjustment Based on Left Ventricular Filling Pressures

Functional capacity remains limited in heart failure patients with left ventricular assist devices (LVADs) due to fixed pump speed and inability to offload the left ventricle adequately. We hypothesized that manually adjusting LVAD speed during exercise based on pulmonary capillary wedge pressures would increase total cardiac output and maximal oxygen consumption. Two participants with a HeartWare LVAD underwent an invasive ramp study at rest followed by an invasive cardiopulmonary stress test exercising in two randomized phases: fixed speed and adjusted speed. In the latter phase, speed was adjusted every 1 minute during exercise at ±20 rpm/1 mm Hg change from baseline pulmonary capillary wedge pressure. There was no difference in maximal oxygen consumption between the two phases, with a modest increase in total cardiac output during speed adjustment. Filling pressures were initially controlled during speed adjustment until speed was capped at 4,000 rpm, at which point filling pressures increased. Blood pressure was variable. The pressure across the head of the pump (ΔP) was higher with speed adjustment. Contrary to our hypothesis, LVAD speed adjustment during exercise did not improve total cardiac output and functional capacity. This variable response may be attributed to the native cardiac reserve and baroreceptor response; however, additional studies are needed.

Effectiveness of exercise-based cardiac rehabilitation for patients with left ventricular assist device: A systematic review and meta-analysis

PURPOSE

Exercise-based cardiac rehabilitation (EBCR) improves functional capacity in heart failure (HF). However, data on the effect of EBCR in patients with advanced HF and left ventricular assist devices (LVADs) are limited. This meta-analysis aimed to evaluate the impact of EBCR on the functional ability of LVAD patients by comparing the corresponding outcome indicators between the EBCR and ST groups.

METHODS

PubMed, Embase, Clinical Trials, and Cochrane Library databases were searched for studies assessing and comparing the effects of EBCR and standard therapy (ST) in patients following LVAD implantation. Using pre-defined criteria, appropriate studies were identified and selected. Data from selected studies were extracted in a standardized fashion, and a meta-analysis was performed using a fixed-effects model. The protocol was registered on INPLASY (202340073).

RESULTS

In total, 12 trials involving 477 patients were identified. The mean age of the participants was 52.9 years, and 78.6% were male. The initiation of EBCR varied from LVAD implantation during the index hospitalization to 11 months post-LVAD implantation. The median rehabilitation period ranged from 2 weeks to 18 months. EBCR was associated with improved peak oxygen uptake (VO2) in all trials. Quantitative analysis was performed in six randomized studies involving 214 patients (EBCR: n = 130, ST: n = 84). EBCR was associated with a significantly high peak VO2 (weighted mean difference [WMD] = 1.64 mL/kg/min; 95% confidence interval [CI], 0.20-3.08; p = .03). Similarly, 6-min walk distance (6MWD) showed significantly greater improvement in the EBCR group than in the ST group (WMD = 34.54 m; 95% CI, 12.47-56.42; p = .002) in 266 patients (EBCR, n = 140; ST, n = 126). Heterogeneity was low among the included trials. None of the included studies reported serious adverse events related to EBCR, indicating the safety of EBCR after LVAD implantation.

CONCLUSION

This study demonstrated that EBCR following LVAD implantation is associated with greater improvement in functional capacity compared with ST as reflected by the improved peak VO2 and 6MWD values. Considering the small number of patients in this analysis, further research on the clinical impact of EBCR in LVAD patients is warranted.

Hemodynamic parameters at rest predicting exercise capacity in patients supported with left ventricular assist device

Left ventricular assist devices improve prognosis and quality of life, but exercise capacity remains limited in most patients after device implantation. Left ventricular assist device optimization through right heart catheterization reduces device-related complications. However, hemodynamic parameters associated with exercise capacity under optimized conditions. The aim of this study was to elucidate the predictors of exercise capacity from hemodynamic parameters at rest after left ventricular assist device optimization. We retrospectively reviewed 24 patients who underwent a ramp test with right heart catheterization, echocardiography and cardiopulmonary exercise testing more than 6 months after left ventricular assist device implantation. Pump speed was optimized to a lower setting that achieved right atrial pressure < 12 mmHg, pulmonary capillary wedge pressure < 18 mmHg, and cardiac index > 2.2 L/min/m2, then exercise capacity was assessed by cardiopulmonary exercise testing. After left ventricular assist device optimization, the mean right atrial pressure, pulmonary capillary wedge pressure, cardiac index, and peak oxygen consumption were 7 ± 5 mmHg, 10 ± 7 mmHg, 2.7 ± 0.5 L/min/m2, and 13.2 ± 3.0 mL/min/kg, respectively. Pulse pressure, stroke volume, right atrial pressure, mean pulmonary artery pressure, and pulmonary capillary wedge pressure were significantly associated with peak oxygen consumption. Multivariate linear regression analysis of factors predicting peak oxygen consumption revealed that pulse pressure, right atrial pressure, and aortic insufficiency remained independent predictors (β = 0.401, p = 0.007; β = - 0.558, p < 0.001; β = - 0.369, p = 0.010, respectively). Our findings suggests that cardiac reserve, volume status, right ventricular function, and aortic insufficiency predict exercise capacity in patients with a left ventricular assist device.

Preoperative and mid-term right ventricular systolic function assessment, at rest and during exercise, with speckle-tracking echocardiography after left ventricular assist device implantation

OBJECTIVES

The study aimed to compare pre- and postoperative resting as well as postprocedural resting and exertional right ventricular speckle-tracking echocardiographic parameters at a mid-term follow-up after left ventricular assist device (LVAD) implantation.

METHODS

Patients with implanted third-generation LVADs with hydrodynamic bearings were prospectively enrolled (NCT05063006). Myocardial deformation was evaluated before pump implantation and at least three months after the procedure, both at rest and during exercise.

RESULTS

We included 22 patients, 7.3 months (IQR, 4.7-10.2) after the surgery. The mean age was 58.4 ± 7 years, 95.5% were men, and 45.5% had dilated cardiomyopathy. The RV strain analysis was feasible in all subjects both at rest and during exercise. The RV free wall strain (RVFWS) worsened from -13% (IQR, -17.3 to -10.9) to -11.3% (IQR, -12.9 to -6; p = 0.033) after LVAD implantation with a particular decline in the apical RV segment [-11.3% (IQR, -16.4 to -6.2) vs -7.8% (IQR, -11.7 to -3.9; p = 0.012)]. The RV four-chamber longitudinal strain (RV4CSL) remained unchanged [-8.5% (IQR, -10.8 to -6.9) vs -7.3% (IQR, -9.8 to -4.7; p = 0.184)]. Neither RVFWS (-11.3% (IQR, -12.9 to -6) vs -9.9% (IQR, -13.5 to -7.5; p = 0.077) nor RV4CSL [-7.3% (IQR, -9.8 to -4.7) vs -7.9% (IQR, -9.8 to -6.3; p = 0.548)] changed during the exercise test.

CONCLUSIONS

In patients who are pump-supported, the right ventricular free wall strain tends to worsen after LVAD implantation and remains unchanged during a cycle ergometer stress test.

Exercise Performance and Quality of Life of Left Ventricular Assist Device Patients After Long-Term Outpatient Cardiac Rehabilitation

PURPOSE

Exercise performance and quality of life (QoL) of left ventricular assist device (LVAD) patients improve after early cardiac rehabilitation (CR). The purpose of this study was to examine the efficacy of multiprofessional long term phase 3 outpatient CR, and whether cardiopulmonary exercise testing (CPX) and 6-min walk testing (6MWT) post-LVAD implantation predict hospital readmission.

METHODS

This retrospective observational cohort study included 29 LVAD patients (58.6 ± 7.7 yr, female: 13.8%, body mass index: 29.4 ± 3.3 kg/m 2 ). Functional performance tests (CPX, 6MWT, sit-to-stand test), QoL, and psychological surveys (Kansas City Cardiomyopathy Questionnaire, hospital anxiety and depression scale, and Control Convictions about Disease and Health [KKG]) were performed at baseline and at the end of CR.

RESULTS

The CR was initiated at a median (IQR) of 159 (130-260) d after LVAD implantation for a duration of 340 (180-363) d with 46.8 ± 23.2 trainings. The 6MWT (408.4 ± 113.3 vs 455.4 ± 115.5 m, P = .003) and sit-to-stand test (16.7 ± 6.9 vs 19.0 ± 5.3 repetitions, P = .033) improved, but relative peak oxygen uptake (V˙ o2peak : 9.4 [8.2-14.4] vs 9.3 [7.8-13.4] mL/min/kg, P = .57) did not change. Using receiver operating characteristic curve analysis, baseline V˙ o2peak values were associated with readmission 1-yr after CR onset (C-statistic = 0.88) with a cutoff value of V˙ o2peak < 9.15 mL/min/kg (100% sensitivity, 78% specificity, P < .001). The Kansas City Cardiomyopathy Questionnaire self-efficacy and knowledge (+6.3 points), QoL (+5.0 points), and social limitation (+7.1 points) demonstrated clinically important changes. In addition, the hospital anxiety and depression scale showed a significant reduction in anxiety (4.6 ± 3.2 vs 2.6 ± 2.4, P = .03).

CONCLUSIONS

Long-term CR is safe and LVAD outpatients showed improvement of QoL, anxiety, and submaximal exercise performance. In addition, V˙ o2peak and 6MWT have prognostic value for readmission.

Clinical myocardial recovery in advanced heart failure with long term left ventricular assist device support

Left ventricular assist-device (LVAD) implantation is a life-saving therapy for patients with advanced heart failure (HF). With chronic unloading and circulatory support, LVAD-supported hearts often show significant reverse remodeling at the structural, cellular and molecular level. However, translation of these changes into meaningful cardiac recovery allowing LVAD explant is lagging. Part of the reason for this discrepancy is lack of anticipation and hence promotion and evaluation for recovery post LVAD implant. There is additional uncertainty about the long-term course of HF following LVAD explant. In selected patients, however, guided by the etiology of HF, duration of disease and other clinical factors, significant functional improvement and LVAD explantation with long-term freedom from recurrent HF events has been demonstrated to be feasible in a reproducible manner. The identified predictors of myocardial recovery suggest that the elective therapeutic use of potentially less invasive VADs for reversal of HF earlier in the disease process is a future goal that warrants further investigation. Hence, it is prudent to develop and implement tools to predict HF reversibility prior to LVAD implant, optimize unloading-promoted recovery with guideline directed medical therapy and monitor for myocardial improvement. This review article summarizes the clinical aspects of myocardial recovery and together with its companion review article focused on the biological aspects of recovery, they aim to provide a useful framework for clinicians and investigators.

Prognostic Value of Cardiopulmonary Exercise Test Parameters in Ventricular Assist Device Therapy

Cardiopulmonary exercise test (CPET) parameters are established prognosticators in heart failure. However, the prognostic value of preimplantation and postimplantation CPET parameters in left ventricular assist device (LVAD) therapy is unclear and it is evaluated in this study. Adult patients who were implanted with an LVAD and underwent CPET during the preimplantation or postimplantation period were retrospectively analyzed. Five CPET parameters were calculated: vO2 max, oxygen uptake efficiency slope (OUES), VE/vCO2 Slope, VE/vCO2 min, and VE/vCO2 max. The relationship between CPET parameters and postimplantation outcomes was evaluated with multivariable analysis. Pre and postimplantation CPET cohorts included 191 and 122 patients, respectively. Among preimplantation CPET parameters: vO2 max and OUES were associated with 1, 3, and 5 year mortality, VE/vCO2 min was associated with 3 and 5 year mortality, whereas VE/vCO2 Slope was associated with 5 year mortality. From postimplantation CPET parameters: vO2 max was an independent predictor of 3 and 5 year mortality, whereas VE/vCO2 max was an independent predictor of 3 year mortality following LVAD implantation. Preimplantation CPET parameters have a prognostic value for long-term survival following LVAD implantation, whereas their association with early postimplantation outcomes appears to be weaker. Postimplantation vO2 max and VE/vCO2 max values are associated with survival on device support and may provide a second chance for prognostication in patients without preimplantation CPET data.

In Vivo Evaluation of a Physiologic Control System for Rotary Blood Pumps Based on the Left Ventricular Pressure-Volume Loop

Current generation continuous flow assist devices to operate at a fixed speed, which limits preload response and exercise capacity in left ventricular assist device (LVAD) patients. A feedback control system was developed to automatically adjust pump speed based on direct measurements of ventricular loading using a custom cannula tip with an integrated pressure sensor and volume-sensing conductance electrodes. The input to the control system is the integral of the left ventricular (LV) pressure versus conductance loop (PGA) over each cardiac cycle. The feedback control system adjusts pump speed based on the difference between the measured PGA and the desired PGA. The control system and cannula tip were tested in acute ovine studies (n = 5) using the HeartMate II LVAD. The preload response of the control system was evaluated by partially occluding and releasing the inferior vena cava using a vessel loop snare. The cannula tip was integrated onto a custom centrifugal flow LVAD and tested in a 14-day bovine study. The control system adjusted pump support to maintain constant ventricular loading: pump speed increased (decreased) following an increase (decrease) in preload. This study demonstrated in vivo the Starling-like response of an automatic pump control system based on direct measurements of LV loading.

Long-term preservation of functional capacity and quality of life in advanced heart failure patients with bridge to transplant therapy: A report from Japanese nationwide multicenter registry

BACKGROUND

Under the revised heart allocation system in the United States, bridge to transplant (BTT) patients with left ventricular assist device (LVAD) have a longer waitlist period, as they are now lowly prioritized. However, little is known regarding the long-term trajectory of functional capacity (FC) and health-related quality of life (HR-QOL) among BTT-LVAD patients.

METHODS

We retrospectively analyzed 442 consecutive patients with BTT-LVAD between April 2013 and May 2019 from a Japanese nationwide registry. FC (New York Heart Association [NYHA] functional class, peak oxygen uptake [VO₂], and 6-min walk test [6MWT]) and HR-QOL (European Quality of Life [EQ-5D index] and Visual Analogue Scale [EQ-VAS]) were assessed at baseline and for up to 60 months after LVAD implantation.

RESULTS

During the follow-up period of 30 months (IQR 18-42 months), 100 (22.6%) patients underwent transplantation, 37 (8.3%) died, and 14 (3.1%) underwent explantation for recovery. Mean peak VO₂, 6MWT distance, EQ-5D index, and EQ-VAS significantly improved 3 months after LVAD implantation (p = 0.0012, p = 0.0037, p < 0.001, p < 0.001, respectively). Furthermore, these improvements were sustained for up to 60 months following LVAD implantation. Major adverse events including device failure, infection, stroke, and bleeding, which occurred within the first 3 months after LVAD implantation may have not affected FC or HR-QOL for up to 60 months (p = 0.15, p = 0.22, respectively).

CONCLUSIONS

BTT patients showed long-term preservation of FC and HR-QOL, suggesting that BTT remains an option despite the long waiting time to HTx.

Echo-guided left ventricular assist device speed optimisation for exercise maximisation

Objective

Current generation left ventricular assist devices (LVADs) operate with a fixed rotation speed and no automated speed adjustment function. This study evaluates the concept of physiological pump speed optimisation based on aortic valve opening (AVO) imaging during a cardiopulmonary exercise test (CPET).

Methods

This prospective crossover study (NCT05063006) enrolled patients with implanted third-generation LVADs with hydrodynamic bearing. After resting speed optimisation, patients were randomised to a fixed-modified speed or modified-fixed speed CPET sequence. Fixed speed CPET maintained baseline pump settings. During the modified speed CPET, the LVAD speed was continuously altered to preserve periodic AVO.

Results

We included 22 patients, the mean age was 58.4±7 years, 4.5% were women and 54.5% had ischaemic cardiomyopathy. Exertional AVO assessment was feasible in all subjects. Maintaining periodic AVO allowed to safely raise the pump speed from 2900 (IQR 2640–3000) to 3440 revolutions per minute (RPM) (IQR 3100–3700; p<0.001). As a result, peak oxygen consumption increased from 11.1±2.4 to 12.8±2.8 mL/kg/min (p<0.001) and maximum workload from 1.1 (IQR 0.9–1.5) to 1.2 W/kg (IQR 0.9–1.7; p=0.028). The Borg scale exertion level decreased from 15.2±1.5 to 13.5±1.2 (p=0.005).

Conclusions

Transthoracic AVO imaging is possible during CPETs in patients with LVAD. Dynamic echo-guided pump speed adjustment based on the AVO improves exercise tolerance and augments peak oxygen consumption and maximum workload.

Top Ten Tips Palliative Care Clinicians Should Know About Solid Organ Transplantation

Solid organ transplantation (SOT) is a life-saving procedure for people with end-stage organ failure. However, patients experience significant symptom burden, complex decision making, morbidity, and mortality during both pre- and post-transplant periods. Palliative care (PC) is well suited and historically underdelivered for the transplant population. This article, written by a team of transplant specialists (surgeons, cardiologists, nephrologists, hepatologists, and pulmonologists), PC clinicians, and an ethics specialist, shares 10 high-yield tips for PC clinicians to consider when caring for SOT patients.

Relationship between spleen size and exercise tolerance in advanced heart failure patients with a left ventricular assist device

OBJECTIVE

Spleen volume increases in patients with advanced heart failure (HF) after left ventricular assist device (LVAD) implantation. However, the relationship between spleen volume and exercise tolerance (peak oxygen consumption [VO₂]) in these patients remains unknown. In this exploratory study, we enrolled 27 patients with HF using a LVAD (median age: 46 years). Patients underwent blood testing, echocardiography, right heart catheterization, computed tomography (CT), and cardiopulmonary exercise testing. Spleen size was measured using CT volumetry, and the correlations/causal relationships of factors affecting peak VO₂ were identified using structural equation modeling.

RESULTS

The median spleen volume was 190.0 mL, and peak VO₂ was 13.2 mL/kg/min. The factors affecting peak VO₂ were peak heart rate (HR; β = 0.402, P = .015), pulmonary capillary wedge pressure (PCWP; β =  - 0.698, P = .014), right ventricular stroke work index (β = 0.533, P = .001), blood hemoglobin concentration (β = 0.359, P = .007), and spleen volume (β = 0.215, P = .041). Spleen volume correlated with peak HR, PCWP, and hemoglobin concentration, reflecting sympathetic activity, cardiac preload, and oxygen-carrying capacity, respectively, and was thus related to peak VO₂. These results suggest an association between spleen volume and exercise tolerance in advanced HF.

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.

Cardiopulmonary Exercise Testing With Echocardiography to Assess Recovery in Patients With Ventricular Assist Devices

The left ventricular assist device (LVAD) is an established treatment for select patients with end-stage heart failure. Some patients recovered and are considered for explantation. Assessing recovery involves exercise testing and echo ramping on full and minimal LVAD support. Combined cardiopulmonary exercise testing with simultaneous echo ramping (CPET-R) has not been well studied. Patients were included if they had CPET within the previous 6 months, were clinically stable, and had an INR >2.0 on the day of examination. Patients had CPET-R on two occasions within 14 days: (a) with LVAD at therapeutic speed and (b) with LVAD at the lowest speed possible. Six patients were between 29 and 75 years (two female). One patient did not complete a turn-down test due to evidence of ischemia on initial CPET-R subsequently confirmed as a significant coronary artery stenosis on angiography. There were no significant differences in CPET or echo metrics between LVAD speeds. Two patients were explanted due to presumed LV recovery and remained event free for 30 and 47 months, respectively. Serial CPET-R seems safe and feasible for the evaluation of LV and global function and may result in improved clinical decision making for LVAD explantation.

Depressive symptoms interfere with the improvement in exercise capacity by cardiac rehabilitation after left ventricular assist device implantation

BACKGROUND

Although depressive symptoms are associated with an increased risk of readmission after left ventricular assist device (LVAD) implantation, it is unclear whether they affect the efficacy of exercise-based cardiac rehabilitation (EBCR). This study aimed to investigate the effect of depressive symptoms on EBCR efficacy.

METHODS

We analyzed 48 patients who participated in EBCR after LVAD implantation (mean age 45 ± 12 years; 60% male). Patients were classified into two groups using the Zung Self-Rating Depression Scale (SDS): depressive group (SDS ≥40, n = 27) and non-depressive group (SDS <40, n = 21). We examined changes in peak oxygen uptake (VO₂ ), knee extensor muscular strength (KEMS), and quality of life (QOL) during EBCR using analysis of covariance.

RESULTS

Although baseline characteristics were similar between the two groups, the non-depressive group was less likely to receive diuretics (22% vs. 52%, p = 0.030). Peak VO₂ , KEMS, and QOL significantly increased over time in both groups (all p < 0.05). The depressive group had a significantly lower change in peak VO₂ than the non-depressive group (2.7 vs. 1.6 ml/kg/min; mean difference: -1.1 ml/kg/min, 95% confidence interval [CI]: -0.045 to -2.17; p = 0.041, d = 0.59). There was no between-group difference regarding the change in KEMS or QOL. Adjusting for the baseline value, a significant difference between groups was observed only in peak VO₂ (p = 0.045).

CONCLUSIONS

Although EBCR significantly improved exercise capacity after LVAD implantation, depressive symptoms interfered with this improvement. Further studies are needed to determine whether psychological interventions for depression, in addition to EBCR, would improve the response to EBCR after LVAD implantation.

Cardiac Rehabilitation in German Speaking Countries of Europe-Evidence-Based Guidelines from Germany, Austria and Switzerland LLKardReha-DACH-Part 2

Background: Scientific guidelines have been developed to update and harmonize exercise based cardiac rehabilitation (ebCR) in German speaking countries. Key recommendations for ebCR indications have recently been published in part 1 of this journal. The present part 2 updates the evidence with respect to contents and delivery of ebCR in clinical practice, focusing on exercise training (ET), psychological interventions (PI), patient education (PE). In addition, special patients’ groups and new developments, such as telemedical (Tele) or home-based ebCR, are discussed as well. Methods: Generation of evidence and search of literature have been described in part 1. Results: Well documented evidence confirms the prognostic significance of ET in patients with coronary artery disease. Positive clinical effects of ET are described in patients with congestive heart failure, heart valve surgery or intervention, adults with congenital heart disease, and peripheral arterial disease. Specific recommendations for risk stratification and adequate exercise prescription for continuous-, interval-, and strength training are given in detail. PI when added to ebCR did not show significant positive effects in general. There was a positive trend towards reduction in depressive symptoms for “distress management” and “lifestyle changes”. PE is able to increase patients’ knowledge and motivation, as well as behavior changes, regarding physical activity, dietary habits, and smoking cessation. The evidence for distinct ebCR programs in special patients’ groups is less clear. Studies on Tele-CR predominantly included low-risk patients. Hence, it is questionable, whether clinical results derived from studies in conventional ebCR may be transferred to Tele-CR. Conclusions: ET is the cornerstone of ebCR. Additional PI should be included, adjusted to the needs of the individual patient. PE is able to promote patients self-management, empowerment, and motivation. Diversity-sensitive structures should be established to interact with the needs of special patient groups and gender issues. Tele-CR should be further investigated as a valuable tool to implement ebCR more widely and effectively.

Exercise capacity following ventricular assist device implantation via thoracotomy with outflow cannula anastomosis to the descending aorta

Left ventricular assist device (LVAD) implantation via left lateral thoracotomy with outflow cannula anastomosis to the descending aorta is an alternative technique that avoids anterior mediastinal planes and requires a single incision. This study compares changes in exercise capacity following LVAD implantation with outflow cannula anastomosis to the descending aorta versus ascending aorta. Adult patients who received a continuous flow centrifugal LVAD implantation and completed both pre- and postimplantation cardiopulmonary exercise tests (CPETs) and or 6-minute walk tests (6MWT) were included. Change in CPET parameters (maximum oxygen intake: vO₂ max, oxygen uptake efficiency ratio: OUES, ventilatory efficiency ratio: vE/vCO₂ Slope) and 6MWT distance were compared between ascending and descending aorta anastomosis groups. Ascending and descending aorta anastomosis cohorts included 59 and 14 patients, respectively. Pre- and postimplantation CPETs were performed 63 ± 12 days before and 216 ± 17 days following implantation. The improvement in CPET parameters (vO₂ max, OUES, vE/vCO₂ Slope) or 6MWT distance was not significantly different between the ascending and descending aorta anastomosis groups. This study found no significant difference in the improvement of CPET parameters or 6MWT distance between LVAD implantation via thoracotomy with outflow cannula anastomosis to descending aorta and standard implantation via sternotomy with outflow cannula anastomosis to ascending aorta.

Effects of echo-optimization of left ventricular assist devices on functional capacity, a randomized controlled trial

Aims

After the implantation of a left ventricular assist device (LVAD), many patients continue to experience exercise intolerance. VAFRACT trial evaluates the additional benefit of LVAD echo‐guided optimization (EO) on functional capacity (FC), measured by cardiopulmonary exercise test (CPET), and quality of life (QoL).

Methods and results

Twenty‐seven patients were randomized in a 1:1 ratio to EO (EO group) vs. standard settings (CONTROL group) at least after 3 months from LVAD implant procedure. The optimal device speed was defined as the one that allows an intermittent aortic valve opening and a neutral position of the interventricular septum without increasing aortic or tricuspid regurgitation and preserving right ventricular function. The primary endpoint was peak oxygen uptake (VO₂ peak) change after 3 months.

Echo‐guided optimization significantly improves VO₂ peak (from 13.2 ± 2.5 to 14.2 ± 2.5 mL/kg/min; P < 0.001), oxygen pulse (from 9.75 ± 1.46 to 10.75 ± 2.2 mL; P < 0.001), CPET exercise time (from 490 ± 98 to 526 ± 116 s; P = 0.02), 6 min walk distance (from 363 ± 54 to 391 ± 52 m; P = 0.04), and QoL, using EuroQol Five Dimensions 3L (from 0.796 ± 0.1 to 0.85 ± 0.08; P < 0.001) and the Kansas City Cardiomyopathy Questionnaire (from 81.6 ± 6.9 to 84.6 ± 5.6; P = 0.025).

Conclusions

Echo‐guided optimization can significantly influence the FC and the QoL of LVAD patients. This procedure should represent a fundamental step in their clinical management, through the establishment of consolidated follow‐up protocols. Our study may represent a starting point for a future, adequately powered clinical trial with a longer term follow‐up.

Exercise physiology in left ventricular assist device patients: insights from hemodynamic simulations

Left ventricular assist devices (LVADs) assure longer survival to patients, but exercise capacity is limited compared to normal values. Overall, LVAD patients show high wedge pressure and low cardiac output during maximal exercise, a phenomenon hinting at the need for increased LVAD support. Clinical studies investigating the hemodynamic benefits of an LVAD speed increase during exercise, ended in inhomogeneous and sometimes contradictory results. The native ventricle-LVAD interaction changes between rest and exercise, and this evolution is complex, multifactorial and patient-specific. The aim of this paper is to provide a comprehensive overview on the patient-LVAD interaction during exercise and to delineate possible therapeutic strategies for the future. A computational cardiorespiratory model was used to simulate the hemodynamics of peak bicycle exercise in LVAD patients. The simulator included the main cardiovascular and respiratory impairments commonly observed in LVAD patients, so as to represent an average hemodynamic response to exercise. In addition, other exercise responses were simulated, by tuning the chronotropic, inotropic and vascular functions, and implementing aortic regurgitation and stenosis in the simulator. These profiles were tested under different LVAD speeds and LVAD pressure-flow characteristics. Simulations output showed consistency with clinical data from the literature. The simulator allowed the working condition of the assisted ventricle at exercise to be investigated, clarifying the reasons behind the high wedge pressure and poor cardiac output observed in the clinics. Patients with poorer inotropic, chronotropic and vascular functions, are likely to benefit more from an LVAD speed increase during exercise. Similarly, for these patients, a flatter LVAD pressure-flow characteristic can assure better hemodynamic support under physical exertion. Overall, the study evidenced the need for a patient-specific approach on supporting exercise hemodynamics. In this frame, a complex simulator can constitute a valuable tool to define and test personalized speed control algorithms and strategies.

One year improvement of exercise capacity in patients with mechanical circulatory support as bridge to transplantation

AIMS

Mechanical circulatory support (MCS) results in substantial improvement of prognosis and functional capacity. Currently, duration of MCS as a bridge to transplantation (BTT) is often prolonged due to shortage of donor hearts. Because long-term results of exercise capacity after MCS are largely unknown, we studied serial cardiopulmonary exercise tests (CPETs) during the first year after MCS implantation.

METHODS AND RESULTS

Cardiopulmonary exercise tests at 6 and 12 months after MCS implantation in BTT patients were retrospectively analysed, including clinical factors related to exercise capacity. A total of 105 MCS patients (67% male, 50 ± 12 years) underwent serial CPET at 6 and 12 months after implantation. Power (105 ± 35 to 114 ± 40 W; P ≤ 0.001) and peak VO2 per kilogram (pVO2/kg) improved significantly (16.5 ± 5.0 to 17.2 ± 5.5 mL/kg/min (P = 0.008)). Improvement in pVO2 between 6 and 12 months after LVAD implantation was not related to heart failure aetiology or haemodynamic severity prior to MCS. We identified maximal heart rate at exercise as an important factor for pVO2. Younger age and lower BMI were related to further improvement. At 12 months, 25 (24%) patients had a normal exercise capacity (Weber classification A, pVO2 > 20 mL/kg/min).

CONCLUSIONS

Exercise capacity (power and pVO2) increased significantly between 6 and 12 months after MCS independent of Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile or heart failure aetiology. Heart rate at exercise importantly relates to exercise capacity. This long-term improvement in exercise capacity is important information for the growing group of long-term MCS patients as this is critical for the quality of life of patients.

The left ventricular assist device as a patient monitoring system

Technological progress of left ventricular assist devices (LVADs) towards rotary blood pumps and the optimization of medical management contributed to the significant improvements in patient survival as well as LVAD support duration. Even though LVAD therapy is now well-established for end-stage heart failure patients, the long-term occurrence of adverse events (AE) such as bleeding, infection or stroke, still represent a relevant burden. An early detection of AE, before onset of major symptoms, can lead to further optimization of patient treatment and thus mitigate the burden of AE. Continuous patient monitoring facilitates identification of pathophysiological states and allows anticipation of AE to improve patient management. In this paper, methods, algorithms and possibilities for continuous patient monitoring based on LVAD data are reviewed. While experience with continuous LVAD monitoring is currently limited to a few centers worldwide, the pace of developments in this field is fast and we expect these technologies to have a global impact on the well-being of LVAD patients.

Markers of Right Ventricular Dysfunction Predict Maximal Exercise Capacity After Left Ventricular Assist Device Implantation

Although left ventricular assist device (LVAD) improves functional capacity, on average LVAD patients are unable to achieve the aerobic capacity of normal healthy subjects or mild heart failure patients. The aim of this study was to examine if markers of right ventricular (RV) function influence maximal exercise capacity. This was a single-center prospective study that enrolled 20 consecutive HeartWare ventricular assist device patients who were admitted at the Freeman Hospital (Newcastle upon Tyne, United Kingdom) for a heart transplant assessment from August 2017 to October 2018. Mean peak oxygen consumption (Peak VO2) was 14.0 ± 5.0 ml/kg/min, and mean peak age and gender-adjusted percent predicted oxygen consumption (%VO2) was 40.0% ± 11.5%. Patients were subdivided into two groups based on the median peak VO2, so each group consisted of 10 patients (50%). Right-sided and pulmonary pressures were consistently higher in the group with poorer exercise tolerance. Patients with poor exercise tolerance (peak VO2 below the median) had higher right atrial pressures at rest (10.6 ± 6.4 vs. 4.3 mmHg ± 3.2; p = 0.02) and the increase with passive leg raising was significantly greater than those with preserved exercise tolerance (peak VO2 above the median). Patients with poor functional capacity also had greater RV dimensions (4.4 cm ± 0.5 vs. 3.7 cm ± 0.5; p = 0.02) and a higher incidence of significant tricuspid regurgitation (moderate or severe tricuspid regurgitation in five patients in the poor exercise capacity group vs. none in the preserved exercise capacity group; p = 0.03). In conclusion, echocardiographic and hemodynamic markers of RV dysfunction discriminate between preserved and nonpreserved exercise capacity in HeartWare ventricular assist device patients.

Right ventricular function and cardiopulmonary performance among patients with heart failure supported by durable mechanical circulatory support devices

BACKGROUND

Patients with continuous-flow left ventricular assist devices (CF-LVADs) experience limitations in functional capacity and frequently, right ventricular (RV) dysfunction. We sought to characterize RV function in the context of global cardiopulmonary performance during exercise in this population.

METHODS

A total of 26 patients with CF-LVAD (aged 58 ± 11 years, 23 males) completed a hemodynamic assessment with either conductance catheters (Group 1, n = 13) inserted into the right ventricle to generate RV pressure‒volume loops or traditional Swan‒Ganz catheters (Group 2, n = 13) during invasive cardiopulmonary exercise testing. Hemodynamics were collected at rest, 2 sub-maximal levels of exercise, and peak effort. Breath-by-breath gas exchange parameters were collected by indirect calorimetry. Group 1 participants also completed an invasive ramp test during supine rest to determine the impact of varying levels of CF-LVAD support on RV function.

RESULTS

In Group 1, pump speed modulations minimally influenced RV function. During upright exercise, there were modest increases in RV contractility during sub-maximal exercise, but there were no appreciable increases at peak effort. Ventricular‒arterial coupling was preserved throughout the exercise. In Group 2, there were large increases in pulmonary arterial, left-sided filling, and right-sided filling pressures during sub-maximal and peak exercises. Among all participants, the cardiac output‒oxygen uptake relationship was preserved at 5.8:1. Ventilatory efficiency was severely abnormal at 42.3 ± 11.6.

CONCLUSIONS

Patients with CF-LVAD suffer from limited RV contractile reserve; marked elevations in pulmonary, left-sided filling, and right-sided filling pressures during exercise; and severe ventilatory inefficiency. These findings explain mechanisms for persistent reductions in functional capacity in this patient population.

Role of Cardiac Rehabilitation After Ventricular Assist Device Implantation

Patients with heart failure suffered by a complex syndrome, where the filling of the ventricle or ejection of the blood is impaired. In this setting, the exercise capacity decreases for many reasons, one of them being the insufficient oxygen transfer due to reduced cardiac output and anemia. Ventricular assist device has emerged as a durable and safe therapy for patients with end-stage heart failure. The benefits of cardiac rehabilitation in ventricular assist device patients are enormous: the first aim is to progressively reduce the physical and functional impairments of these patients, so that they will be able to resume meaningful daily activities.

Clinical Outcomes, Trends in Weight, and Weight Loss Strategies in Patients With Obesity After Durable Ventricular Assist Device Implantation

PURPOSE OF REVIEW

To discuss clinical outcomes, changes in weight, and weight loss strategies of patients with obesity post left ventricular assist device (LVAD) implantation.

RECENT FINDINGS

Despite increased complications in patients with obesity after LVAD implantation, survival is comparable to patients without obesity. A minority of patients with obesity lose significant weight and become eligible for heart transplantation after LVAD implantation. In fact, a great majority of such patients gain weight post-implantation. Obesity by itself should not be considered prohibitive for LVAD therapy but, rather, should be incorporated into the overall risk assessment for LVAD implantation. Concerted strategies should be developed to promote sustainable weight loss in patients with obesity and LVAD to improve quality of life, eligibility, and outcomes after heart transplantation. Investigation of the long-term impact of weight loss on patients with obesity with LVAD is warranted.

High Right Ventricular Afterload Is Associated with Impaired Exercise Tolerance in Patients with Left Ventricular Assist Devices

Patients with left ventricular assist device (LVAD) have poor exercise tolerance. We aimed to characterize relationship between right ventricular (RV) afterload and exercise capacity, RV reserve, and adaptation to load. Twelve well-compensated LVAD subjects underwent right heart catheterization at rest and during symptom-limited exercise. Cardiopulmonary exercise tests were also performed. Hemodynamics were compared with age- and sex-matched subjects with pulmonary arterial hypertension (PAH) and normal non-athletes. Hemodynamic changes were expressed as Δ(exercise - rest). At rest, LVAD subjects had normal biventricular pressures and cardiac output (CO). On exercise, despite similar increases in pulmonary artery wedge pressure (PAWP) between three groups, RV afterload increased only in LVAD cohort (pulmonary elastance [ΔEa] LVAD: 0.4, PAH: 0.1, normal: 0.1 mmHg/ml, p = 0.0024). This afterload increase coincided with the largest rise in right atrial pressure (RAP), lowest change in RV stroke work index, and smallest CO augmentation (ΔCO LVAD: 1.5, PAH: 4.3, normal: 5.7 L/min, p = 0.0014). Peak VO2 negatively correlated with RV afterload (Ea) (r = -0.8, p = 0.0101), while VE/VCO2 slope had the inverse correlation. During exercise, pulmonary artery pulsatility index worsened while RAP:PAWP ratio was unchanged in LVAD subjects. Well-compensated LVAD patients had poor RV reserve and adaptation to load on exercise compared with PAH and normal subjects.

Exercise Tolerance in Patients Treated With a Durable Left Ventricular Assist Device: Importance of Myocardial Recovery

The number of patients supported with left ventricular assist devices (LVADs) is growing and support times are increasing. This has led to a greater focus on functional capacity of these patients. LVADs greatly improve heart failure symptoms, but surprisingly, improvement in peak oxygen uptake (pVO₂) is small and remains decreased at approximately 50% of normal values. Inadequate increase in cardiac output during exercise is the main responsible factor for the low pVO₂ in LVAD recipients. Some patients experience LV recovery during mechanical unloading and these patients have a higher pVO₂. Here we review the various components determining exercise cardiac output in LVAD recipients and discuss the potential impact of cardiac recovery on these components. LV recovery may affect several components, leading to improved hemodynamics during exercise and, in turn, physical capacity in patients with advanced heart failure undergoing LVAD implantation.

Determinants of Functional Capacity and Quality of Life After Implantation of a Durable Left Ventricular Assist Device

Continuous-flow left ventricular assist devices (LVAD) are increasingly used as destination therapy in patients with end-stage heart failure and, with recent improvements in pump design, adverse event rates are decreasing. Implanted patients experience improved survival, quality of life (QoL) and functional capacity (FC). However, improvement in FC and QoL after implantation is not unequivocal, and this has implications for patient selection and preimplantation discussions with patients and relatives. This article identifies preimplantation predictors of lack of improvement in FC and QoL after continuous-flow LVAD implantation and discusses potential mechanisms, allowing for the identification of potential factors that can be modified. In particular, the pathophysiology behind insufficient improvement in peak oxygen uptake is discussed. Data are included from 40 studies, resulting in analysis of >700 exercise tests. Mean peak oxygen uptake was 13.4 ml/kg/min (equivalent to 48% of predicted value; 259 days after implantation, range 31–1,017 days) and mean 6-minute walk test distance was 370 m (182 days after implantation, range 43–543 days). Finally, the interplay between improvement in FC and QoL is discussed.

Left Ventricular Assist Device as Destination Therapy: a State of the Science and Art of Long-Term Mechanical Circulatory Support

PURPOSE OF REVIEW

The purpose of this review is to synthesize and summarize recent developments in the care of patients with end-stage heart failure being managed with a left ventricular assist device (LVAD) as destination therapy.

RECENT FINDINGS

Although the survival of patients treated with LVAD continues to improve, the rates of LVAD-associated complication, such as right ventricular failure, bleeding complications, and major infection, remain high, and management of these patients remains challenging. The durability and hemocompatibility of LVAD support have greatly increased in recent years as a result of new technologies and novel management strategies. Challenges remain in the comprehensive care of patients with destination therapy LVADs, including management of comorbidities and optimizing patient function and quality of life.

Associations between hemodynamic parameters at rest and exercise capacity in patients with implantable left ventricular assist devices

BACKGROUND

Hemodynamic parameters at rest are known to correlate poorly with peak oxygen uptake (VO₂) in heart failure. However, we hypothesized that hemodynamic parameters at rest could predict exercise capacity in patients with left ventricular assist device (LVAD), because LVAD pump rotational speed does not respond during exercise. Therefore, we investigated the relationships between hemodynamic parameters at rest (measured with right heart catheterization) and exercise capacity (measured with cardiopulmonary exercise testing) in patients with implantable LVAD.

METHODS

We performed a retrospective medical record review of patients who received implantable LVAD at our institution from November 2013 to December 2017.

RESULTS

A total of 20 patients were enrolled in this study (15 males; mean age, 45.8 years; median duration of LVAD support, 356 days). The mean peak VO₂ and cardiac index (CI) were 13.5 mL/kg/min and 2.6 L/min/m², respectively. CI and hemoglobin level were significantly associated with peak VO₂ (CI: r = 0.632, p = 0.003; hemoglobin: r = 0.520, p = 0.019). In addition, pulmonary capillary wedge pressure, right atrial pressure, and right ventricular stroke work index were also significantly associated with peak VO₂. In multiple linear regression analysis, CI and hemoglobin level remained independent predictors of peak VO₂ (CI: β = 0.559, p = 0.006; hemoglobin: β = 0.414, p = 0.049).

CONCLUSIONS

CI at rest and hemoglobin level are associated with poor exercise capacity in patients with LVAD.

Limiting factors of peak and submaximal exercise capacity in LVAD patients

AIMS

Although patients supported with a Continuous-Flow Left Ventricular Assist Device (CF-LVAD) are hemodynamically stable, their exercise capacity is limited. Hence, the aim of this work was to investigate the underlying factors that lead to peak and submaximal exercise intolerance of CF-LVAD supported patients.

METHODS

Seven months after CF-LVAD implantation, eighty three patients performed a maximal cardiopulmonary exercise test and a six minute walk test. Peak oxygen uptake and the distance walked were measured and expressed as a percentage of the predicted value (%VO2p and %6MWD, respectively). Preoperative conditions, echocardiography, laboratory results and pharmacological therapy data were collected and a correlation analysis against %VO2p and %6MWD was performed.

RESULTS

CF-LVAD patients showed a relatively higher submaximal exercise capacity (%6MWD = 64±16%) compared to their peak exertion (%VO2p = 51±14%). The variables that correlated with %VO2p were CF-LVAD parameters, chronotropic response, opening of the aortic valve at rest, tricuspid insufficiency, NT-proBNP and the presence of a cardiac implantable electronic device. On the other hand, the variables that correlated with %6MWD were diabetes, creatinine, urea, ventilation efficiency and CF-LVAD pulsatility index. Additionally, both %6MWD and %VO2p were influenced by the CF-LVAD implantation timing, calculated from the occurrence of the cardiac disease.

CONCLUSION

Overall, both %6MWD and %VO2p depend on the duration of heart failure prior to CF-LVAD implantation. %6MWD is primarily determined by parameters underlying the patient's general condition, while %VO2p mostly relies on the residual function and chronotropic response of the heart. Moreover, since %VO2p was relatively lower compared to %6MWD, we might infer that CF-LVAD can support submaximal exercise but is not sufficient during peak exertion. Hence concluding that the contribution of the ventricle is crucial in sustaining hemodynamics at peak exercise.

Haemodynamic Effect of Left Atrial and Left Ventricular Cannulation with a Rapid Speed Modulated Rotary Blood Pump During Rest and Exercise: Investigation in a Numerical Cardiorespiratory Model

PURPOSE

The left atrium and left ventricle are the primary inflow cannulation sites for heart failure patients supported by rotary blood pumps (RBPs). Haemodynamic differences exist between inflow cannulation sites and have been well characterized at rest, yet the effect during exercise with the same centrifugal RBP has not been previously well established. The purpose of this study was to investigate the hemodynamic effect of inflow cannulation site during rest and exercise with the same centrifugal RBP.

METHODS

In a numerical cardiorespiratory model, a simulated heart failure patient was supported by a HeartWare HVAD RBP in left atrial (LAC) and left ventricular cannulation (LVC). The RBP was operated at constant speed and sinusoidal co- and counter-pulse and was investigated in cardiovascular conditions of steady state rest and 80-watt bike graded exercise.

RESULTS

Cardiac output was 5.0 L min^-1 during rest and greater than 6.9 L min^-1 during exercise for all inflow cannulation sites and speed operating modes. However, during exercise, LAC demonstrated greater pressure-volume area and lower RBP flow (1.41, 1.37 and 1.37 J and 5.03, 5.12 and 5.03 L min^-1 for constant speed and co- and counter-pulse respectively) when compared to LVC (pressure-volume area: 1.30, 1.27 and 1.32 J and RBP flow: 5.56, 5.71 and 5.59 L min^-1 for constant speed and co- and counter-pulse respectively).

CONCLUSION

For a simulated heart failure patient intending to complete exercise, LVC seems to assure a better hemodynamic performance in terms of pressure-volume area unloading and increasing RBP flow.

Characteristics, Therapeutic Needs, and Scope of Patients With a Continuous-Flow Left Ventricular Device Entering Cardiac Rehabilitation: A RETROSPECTIVE ANALYSIS

BACKGROUND

With an increasing number of left ventricular assist devices (LVADs) being implanted, the need for adequate cardiac rehabilitation (CR) regimens meeting the special needs of these patients arises. Only a few studies have reported experience gained on this topic. Structured CR strategies are poorly implemented. The aim was to evaluate the characteristics, therapeutic needs, and scope of LVAD patients at admission to CR within a greater cohort in order to identify their special CR needs.

METHODS

Retrospective single-center study; 69 LVAD patients (50.7 ± 13.6 y; 59 male; 48 HVAD; 21 HeartMate II) who completed first inpatient CR were included. Patient records were used to document relevant medical information (including the results of a 6-min walk test and a maximal isometric strength test for quadriceps femoral muscles in both legs) and the International Classification of Functioning, Disability and Health for classification of health and health-related domains.

RESULTS

Patient characteristics demonstrated a heterogeneous group: CR was started 44 ± 38.6 d after implantation; CR duration was 28 ± 9.7 d. Despite similar etiology, physical and psychological condition was diverse, although, overall a high degree of impairment was present, especially in the body function (79.7%) and activity and participation (95.7%) domains. The results demonstrated the need for a highly individualized approach in the somatic and also in the education, psychosocial, and social therapeutic regimes.

CONCLUSION

The results demonstrate a heterogeneous group with a high level of impairment and special needs in many CR domains. The development and evaluation of a special highly individualized approach of CR, which meets the special needs of these patients, is needed.

Predictors of Physical Capacity 6 Months After Implantation of a Full Magnetically Levitated Left Ventricular Assist Device: An Analysis From the ELEVATE Registry

BACKGROUND

In patients with a continuous-flow left ventricular assist device, preimplant predictors of poor physical performance are not well-described. We aimed to identify predictors of inability to walk more than 300 m on 6-minute walk test (6MWT) 6 months after HeartMate 3 implantation.

METHODS AND RESULTS

Using data from the European Registry of Patients Implanted With a Full Magnetically Levitated LVAD, patients with available 6MWT at 6 months after implantation were included (N = 194) and grouped according to 6MWT distance (6MWD) of >300 m (n = 150) or 6MWD of <300 m (n = 44). Patients walking <300 m were older (60 ± 10 vs 52 ± 12 years; P < .001), more often New York Heart Association functional class IV (63% vs 42%; P = .03), and more often had type 2 diabetes (43% vs 17%; P < .001) at implantation. Atrial fibrillation was seen in 57% in those with a 6MWT of <300 m vs 31% in those walking longer (P < .002). Further, hemoglobin and estimated glomerular filtration rate was lower in those walking <300 m (both P < .01). In multivariable regression analysis, independent predictors of a 6MWD of <300 m were: atrial fibrillation (odds ratio [OR], 3.22; 95% confidence interval [CI], 1.12-8.67), older age (OR for 10-year increment, 2.81; 95% CI, 1.55-5.07), New York Heart Association functional class IV (OR, 3.37; 95% CI, 1.27-8.98), and Interagency Registry for Mechanically Assisted Circulatory Support profile 1 or 2 (OR, 6.53; 95% CI, 1.92-22.19).

CONCLUSIONS

Six months after HeartMate 3 implantation, 77% of patients walked >300 meters in 6 minutes. Apart from age and measures of heart failure severity, atrial fibrillation at implantation is an independent predictor of low 6MWD at 6 months after implantation.

Cannula Tip With Integrated Volume Sensor for Rotary Blood Pump Control: Early-Stage Development

The lack of direct measurement of left ventricular unloading is a significant impediment to the development of an automatic speed control system for continuous-flow left ventricular assist devices (cf-LVADs). We have developed an inlet cannula tip for cf-LVADs with integrated electrodes for volume sensing based on conductance. Four platinum-iridium ring electrodes were installed into grooves on a cannula body constructed from polyetheretherketone (PEEK). A sinusoidal current excitation waveform (250 μA pk-pk, 50 kHz) was applied across one pair of electrodes, and the conductance-dependent voltage was sensed across the second pair of electrodes. The conductance catheter was tested in an acute ovine model (n = 3) in conjunction with the HeartMate II rotary blood pump to provide circulatory support and unload the ventricle. Echocardiography was used to measure ventricular size during pump support for verification for the conductance measurements. The conductance measurements correlated linearly with the echocardiography dimension measurements more than the full range of pump support from minimum support to suction. This cannula tip will enable the development of automatic control systems to optimize pump support based on a real-time measurement of ventricular size.

Bionic women and men - Part 4: Cardiovascular, cerebrovascular and exercise responses among patients supported with left ventricular assist devices

NEW FINDINGS

LVAD patients are predisposed to hypertension which may increase the risk of stroke. Hypertension may result from markedly elevated levels of sympathetic nerve activity, which occurs through a baroreceptor-mediated pathway in response to chronic exposure to a non-physiologic (and reduced) pulse. Cerebral autoregulatory processes appear to be preserved in the absence of a physiologic pulse. Nevertheless, the rate of ischemic/embolic and hemorrhagic stroke is unacceptably high and is a major cause of morbidity and mortality in these patients. Despite normalization of a resting cardiac output, LVAD patients suffer from persistent, severe reductions in functional capacity.

ABSTRACT

Current generation left ventricular assist devices (LVADs) have led to significant improvements in survival compared to medical therapy alone, when used for management of patients with advanced heart failure. However, there are a number of side-effects associated with LVAD use, including hypertension, gastrointestinal bleeding, stroke, as well as persistent and severe limitations in functional capacity despite normalization of a resting cardiac output. These issues are, in large part, related to chronic exposure to a non-physiologic pulse, which contributes to a hyperadrenergic environment characterized by markedly elevated levels of sympathetic nerve activity through a baroreceptor-mediated pathway. In addition, these machines are unable to participate in, or contribute to, normal cardiovascular/autonomic reflexes that attempt to modulate flow through the body. Efforts to advance device technology and develop biologically sensitive devices may resolve these issues, and lead to further improvements in quality-of-life, functional capacity, and ultimately, survival, for the patients they support.

Outcomes of Acute Inpatient Rehabilitation After Ventricular Assist Device Placement

OBJECTIVE

The aim of the study was to compare outcomes of inpatient rehabilitation after ventricular assist device placement with outcomes for other cardiac diagnoses.

DESIGN

This was a retrospective review of the electronic health records of 265 patients admitted to inpatient rehabilitation: 166 patients were admitted after ventricular assist device placement and 99 were admitted for other cardiac disease. Data collected included functional independence measure score on admission and discharge, dates of admission and discharge, and disposition.

RESULTS

Patients admitted after ventricular assist device placement had a mean functional independence measure gain of 25.7 and length of stay of 8.7 days. Patients admitted for other cardiac diagnoses had a mean functional independence measure gain of 25.9 and length of stay of 9.4 days. These differences were not statistically significant. Change in functional independence measure from admission to discharge was statistically significant within each group (P < 0.001). Most patients were discharged home, and the proportions who returned to acute care or home were not different between groups.

CONCLUSIONS

Both the ventricular assist device and nonventricular assist device groups had significant and equivalent improvements in functional outcomes after inpatient rehabilitation. This study found that ventricular assist device patients benefit from inpatient rehabilitation with similar disposition rates as patients with other cardiac diagnoses. Inpatient rehabilitation is the appropriate setting for this group.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to: (1) Describe the role of rehabilitation in the care of individuals after ventricular assist device (VAD) placement; (2) Compare the outcomes of inpatient rehabilitation for individuals after VAD placement to those admitted for other cardiac reasons; and (3) Recognize potential complications that may occur during the course of a VAD patient's inpatient rehabilitation stay.

LEVEL

Advanced ACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this Journal-based CME activity for a maximum of 1.0 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.