Outcomes from a recovery protocol for patients with continuous-flow left ventricular assist devices

Longitudinal analysis left ventricular chamber responses under durable LVAD support

BACKGROUND

Left ventricular assist device (LVAD) support offers remodeling potential in some patients. Our goal was to use noninvasively derived pressure-volume (PV) loops to understand the effect of demographic and device variables on serial changes in cardiac function under pump support.

METHODS

Thirty-two consecutive Medtronic HeartWare Ventricular Assist Device (HVAD) patients (mean 55.9 ± 12.3 years, 81.3% male) were prospectively recruited. Single-cycle ventricular pressure and volume were estimated using a validated algorithm. PV loops (n = 77) and corresponding cardiac chamber dynamics were derived at predefined postimplant timepoints (1, 3, 6 months). Changes in PV loop parameters sustained across the 6-month period were characterized using mixed-effects modeling. The influence of demographic and device variables on the observed changes was assessed.

RESULTS

Across a 6-month period, the mean ventricular function parameters remained stable. Significant predictors of monthly improvement of stroke work include: lower pump speeds (2400 rpm vs 2500-2800 rpm) [0.0.051 mm Hg/liter/month (p = 0.001)], high pulsatility index (>1.0 vs <1.0) [0.052 mm Hg/liter/month (p = 0.012)], and ischemic cardiomyopathy indication for LVAD implantation (vs nonischemic) [0.0387 mm Hg/liter/month (p = 0.007)]. Various other cardiac chamber function parameters including cardiac power, peak systolic pressure, and LV elastance also showed improvements in these cohorts.

CONCLUSIONS

Factors associated with improvement in ventricular energetics and hemodynamics under LVAD support can be determined with noninvasive PV loops. Understanding the basis of increasing ventricular load to optimize myocardial remodeling may prove valuable in selecting eligible recovery candidates.

Mechanical circulatory support in cardiogenic shock

Cardiogenic shock is a complex and diverse pathological condition characterized by reduced myocardial contractility. The goal of treatment of cardiogenic shock is to improve abnormal hemodynamics and maintain adequate tissue perfusion in organs. If hypotension and insufficient tissue perfusion persist despite initial therapy, temporary mechanical circulatory support (t-MCS) should be initiated. This decade sees the beginning of a new era of cardiogenic shock management using t-MCS through the accumulated experience with use of intra-aortic balloon pump (IABP) and venoarterial extracorporeal membrane oxygenation (VA-ECMO), as well as new revolutionary devices or systems such as transvalvular axial flow pump (Impella) and a combination of VA-ECMO and Impella (ECPELLA) based on the knowledge of circulatory physiology. In this transitional period, we outline the approach to the management of cardiogenic shock by t-MCS. The management strategy involves carefully selecting one or a combination of the t-MCS devices, taking into account the characteristics of each device and the specific pathological condition. This selection is guided by monitoring of hemodynamics, classification of shock stage, risk stratification, and coordinated management by the multidisciplinary shock team.

Cardiological Challenges Related to Long-Term Mechanical Circulatory Support for Advanced Heart Failure in Patients with Chronic Non-Ischemic Cardiomyopathy

Long-term mechanical circulatory support by a left ventricular assist device (LVAD), with or without an additional temporary or long-term right ventricular (RV) support, is a life-saving therapy for advanced heart failure (HF) refractory to pharmacological treatment, as well as for both device and surgical optimization therapies. In patients with chronic non-ischemic cardiomyopathy (NICM), timely prediction of HF's transition into its end stage, necessitating life-saving heart transplantation or long-term VAD support (as a bridge-to-transplantation or destination therapy), remains particularly challenging, given the wide range of possible etiologies, pathophysiological features, and clinical presentations of NICM. Decision-making between the necessity of an LVAD or a biventricular assist device (BVAD) is crucial because both unnecessary use of a BVAD and irreversible right ventricular (RV) failure after LVAD implantation can seriously impair patient outcomes. The pre-operative or, at the latest, intraoperative prediction of RV function after LVAD implantation is reliably possible, but necessitates integrative evaluations of many different echocardiographic, hemodynamic, clinical, and laboratory parameters. VADs create favorable conditions for the reversal of structural and functional cardiac alterations not only in acute forms of HF, but also in chronic HF. Although full cardiac recovery is rather unusual in VAD recipients with pre-implant chronic HF, the search for myocardial reverse remodelling and functional improvement is worthwhile because, for sufficiently recovered patients, weaning from VADs has proved to be feasible and capable of providing survival benefits and better quality of life even if recovery remains incomplete. This review article aimed to provide an updated theoretical and practical background for those engaged in this highly demanding and still current topic due to the continuous technical progress in the optimization of long-term VADs, as well as due to the new challenges which have emerged in conjunction with the proof of a possible myocardial recovery during long-term ventricular support up to levels which allow successful device explantation.

Estimation of Left Ventricular Stroke Work for Rotary Left Ventricular Assist Devices

Continuous monitoring of left ventricular stroke work (LVSW) may improve the medical management of patients with rotary left ventricular assist devices (LVAD). However, implantable pressure-volume sensors are limited by measurement drift and hemocompatibility. Instead, estimator algorithms derived from rotary LVAD signals may be a suitable alternative. An LVSW estimator algorithm was developed and evaluated in a range of in vitro and ex vivo cardiovascular conditions during full assist (closed aortic valve [AoV]) and partial assist (opening AoV) mode. For full assist, the LVSW estimator algorithm was based on LVAD flow, speed, and pump pressure head, whereas for partial assist, the LVSW estimator combined the full assist algorithm with an estimate of AoV flow. During full assist, the LVSW estimator demonstrated a good fit in vitro and ex vivo (R 2 : 0.97 and 0.86, respectively) with errors of ± 0.07 J. However, LVSW estimator performance was reduced during partial assist, with in vitro : R 2 : 0.88 and an error of ± 0.16 J and ex vivo : R 2 : 0.48 with errors of ± 0.11 J. Further investigations are required to improve the LVSW estimate with partial assist; however, this study demonstrated promising results for a continuous estimate of LVSW for rotary LVADs.

Myocardial recovery following left ventricular assist device implantation

Durable left ventricular assist devices (LVADs) have consistently shown improved mortality and morbidity in patients with end-stage heart failure. Select patients with LVADs may experience significant enough myocardial recovery after device implantation to allow for explantation or decommissioning. While earlier trials suggested a high incidence of recovery, real-world clinical data have demonstrated this to be a much rarer phenomenon. Whether or not patients experience recovery, practices such as speed optimization and usage of guideline-directed medical therapy can improve patient outcomes.

Pulsatile Pressure Delivery of Continuous-Flow Left Ventricular Assist Devices Is Markedly Reduced Relative to Heart Failure Patients

Although continuous-flow left ventricular assist devices (CF-LVADs) provide an augmentation in systemic perfusion, there is a scarcity of in vivo data regarding systemic pulsatility on support. Patients supported on CF-LVAD therapy (n = 71) who underwent combined left/right catheterization ramp study were included. Aortic pulsatility was defined by the pulsatile power index (PPI), which was also calculated in a cohort of high-output heart failure (HOHF, n = 66) and standard HF cohort (n = 44). PPI was drastically lower in CF-LVAD-supported patients with median PPI of 0.006 (interquartile range [IQR], 0.002-0.012) compared with PPI in the HF population at 0.09 (IQR, 0.06-0.17) or HOHF population at 0.25 (IQR, 0.13-0.37; p < 0.0001 among groups). With speed augmentation during ramp, PPI values fell quickly in patients with higher PPI at baseline. PPI correlated poorly with left ventricular ejection fraction (LVEF) in all groups. In CF-LVAD patients, there was a stronger correlation with LV dP/dt (r = 0.41; p = 0.001) than LVEF (r = 0.21; p = 0.08; pint < 0.001). CF-LVAD support is associated with a dramatic reduction in arterial pulsatility as measured by PPI relative to HOHF and HF cohorts and decreases with speed. Further work is needed to determine the applicability to the next generation of device therapy.

Impact of preoperative mitral regurgitation on left ventricular assist device patients: propensity score-matched analysis of the EUROMACS dataset

OBJECTIVES

Mitral regurgitation (MR) is frequently observed in patients undergoing left ventricular assist device implantation. We investigated the impact of preoperative MR on left ventricular assist device patients.

METHODS

A retrospective propensity score-matched analysis of adult patients enrolled in the EUROMACS registry between 1 January 2011 and 30 November 2021 was performed. Patients were divided into 2 groups according to the grade of preoperative MR: none-to-mild (MR 0-II) or moderate-to-severe (MR III-IV).

RESULTS

Following 1:1 propensity score matching, each group consisted of 914 patients. Incidence of postoperative temporary right ventricular support, reoperation for bleeding and dialysis was similar. MR III-IV demonstrated shorter median intensive care unit stay [14 days (6; 27.8) vs 10 days (5; 22), P = 0.004] and ventilation time [72 h (22, 320) vs 31 h (18, 150), P < 0.001]. Mortality was lower for MR III-IV patients [subdistribution hazard ratio: 0.66, 95% confidence interval (CI): 0.59-0.73, P < 0.001]. The 1-year survival was 68.1% (95% CI: 65.1-71.3%) in MR 0-II and 75% (95% CI: 72.1-78%) in MR III-IV. A lower incidence of total complications [odds ratio (OR): 0.93 (0.89-0.98), P = 0.003] and trend towards a lower risk of neurological dysfunction (subdistribution hazard ratio: 0.79; 95% CI: 0.61-1.01, P = 0.063) and sustained ventricular tachycardia [OR: 0.93 (0.54-1.03), P = 0.074] were demonstrated for MR III-IV. The risk of fatal stroke and pump thrombosis was similar.

CONCLUSIONS

Moderate-to-severe MR in patients undergoing left ventricular assist device implantation is associated with better mid-term survival and lower incidence of total major adverse events and complications. The incidence of severe postoperative complications including fatal stroke and device thrombosis was similar.

Novel Plug Device for HeartMate 3 Explantation: First Multicenter Experience

Patients undergoing explantation of left ventricular assist devices (LVADs) after improvement of myocardial function remain a minority. Nevertheless, considering the growing population of LVAD patients, increasing demand for new explantation strategies is expected. Herein, we present a retrospective review of seven patients undergoing HeartMate3 explantation with the use of a custom-made apical ring plug in four medical centers. The primary outcome was status at intensive care unit discharge. Secondary outcomes included perioperative complications and transfusions. Six out of seven patients were males. The median age at explantation and time on LVAD support was 35 years (range:13-73) and 10 months (range:9-24), respectively. No technical difficulties were experienced during plug implantation via a conventional sternotomy or through a left lateral thoracotomy, either with or without cardiopulmonary bypass. Perioperative transfusions ranged from 0 to 3 units/patient. No re-operations for bleeding, hemorrhagic, embolic, or plug-related infective events were observed. Heparin was started 6 hours after surgery as a bridge to oral anticoagulation (international normalized ratio: 2-2.5). All patients were discharged alive from intensive care unit. This novel plug device for HeartMate3 explantation was successfully and safely implanted in this first patient series. Notwithstanding, its use should still be considered off-label and larger studies are required to investigate its long-term results.

Results of non-elective withdrawal of continuous-flow left ventricular assist devices in selected patients

BACKGROUND

Protocols have been developed to identify patients for elective withdrawal of continuous-flow left ventricular device (cfLVAD) support. However, little is known about non-elective explantation or decommissioning of cfLVADs.

METHODS

A retrospective analysis of all patients who underwent left ventricular assist device (LVAD) explantation or decommissioning at a single center between 2002 and 2021 was performed.

RESULTS

Sixty-one patients underwent withdrawal of a cfLVAD (HeartMate II [Abbott] n = 17, HeartMate 3 [Abbott] n = 2, HeartWare HVAD [Medtronic] n = 36, INCOR [Berlin Heart] n = 6). The median follow-up after withdrawal was 1,039 days. The survival at 5 years was 76.1% (95% CI: 64.2%-95.2%). Predictors of worse outcomes in univariate regressive analysis were the duration of heart failure and the age at LVAD implantation. Of the 61 patients, 40 underwent elective withdrawal following a specific protocol. The other twenty-one patients underwent non-elective withdrawal of the cfLVAD because of device infection (n = 12), device thrombosis (n = 6), device malfunction (n = 2) or due to acute intracerebral bleeding (n = 1), also with an excellent survival at 5 years of 81.3%. (95% CI: 63.8-1). The withdrawal was performed in these patients even though they did not fulfill established criteria for successful explantation or decommissioning like clinical stability (n = 21), left ventricular end-diastolic diameter ≤ 55 mm (n = 3), performance of right heart catheterization (n = 6), or pulmonary artery wedge pressure ≤ 15 mm Hg (n = 3).

CONCLUSION

Non-elective withdrawal is possible in selected patients after discussion in a team of experienced cardiac surgeons, cardiologists, technicians, and VAD coordinators. The appropriate preoperative assessment before decommissioning or explantation of a cfLVAD warrants further investigation.

Left Ventricular Assist Device Implantation in Cancer-Therapy-Related Heart Failure

Objectives: Cancer-therapy-related heart failure (CTrHF) due to cardiotoxic drugs or radiation is a growing cause of end-stage heart failure. Limited knowledge is available concerning the use of continuous-flow left-ventricular-assist devices (cfLVAD) in this setting. Methods: The files of all 1334 patients who underwent cfLVAD implantation between December 2008 and December 2020 were screened for the cause of heart failure. All patients with CTrHF were included in the analysis. Results: A total of 32 patients with a median age of 58 years (IQR: 46–65) were included in the study; 15 (47%) were male. The median time from the first diagnosis of heart failure (HF) to cfLVAD implantation was 6 months (IQR 2–24), and from cancer treatment to cfLVAD implantation 40 months (IQR 5–144). Malignancies comprised non-Hodgkin lymphoma (n = 12, 37%), breast cancer (n = 9, 28%), sarcoma (n = 5, 16%), leukemia (n = 5, 16%), and others (n = 1, 3%). In 24 patients, chemotherapy included anthracyclines (others n = 2, unknown n = 6). Chest radiation was performed in 13 patients (39%). Moreover, 71% were classified as INTERMACS profile 1 or 2. The 30-day survival rate after LVAD implantation was 88%. Rethoracotomy was necessary in nine (29%), and a temporary right ventricular assist device in seven (21%) patients. The median survival was 29 months. There was no significant difference in survival or right HF between patients with CTrHF and a matched control group. Conclusions: CfLVAD implantation is feasible in high-risk patients with CTrHF with or without prior chest radiation.

LVAD as a Bridge to Remission from Advanced Heart Failure: Current Data and Opportunities for Improvement

Left ventricular assist devices (LVADs) are an established treatment modality for advanced heart failure (HF). It has been shown that through volume and pressure unloading they can lead to significant functional and structural cardiac improvement, allowing LVAD support withdrawal in a subset of patients. In the first part of this review, we discuss the historical background, current evidence on the incidence and assessment of LVAD-mediated cardiac recovery, and out-comes including quality of life after LVAD support withdrawal. In the second part, we discuss current and future opportunities to promote LVAD-mediated reverse remodeling and improve our pathophysiological understanding of HF and recovery for the benefit of the greater HF population.

Protocolized screening effectively identifies myocardial recovery following destination therapy left ventricular assist device implantation

BACKGROUND

Myocardial recovery following left ventricular assist device (LVAD) implantation has been of interest in transplant candidates with non-ischemic cardiomyopathy but is rare. Evidence suggests that a combination of left ventricular unloading and pharmacologic reverse remodeling is beneficial. Recovery in non-transplant candidates (i.e., destination therapy [DT]) patients is believed to be even rarer.

METHODS

All DT LVADs between January 1, 2017 and November 23, 2020 were reviewed. All patients were subjected to an institutional protocol consisting of combined pharmacologic remodeling and mechanical unloading with proactive screening for recovery. The primary outcome of interest was the cumulative incidence of myocardial recovery. Baseline characteristics and operative outcomes were compared between recovered and non-recovered DT patients using non-parametric tests to identify predictive factors.

RESULTS

A total of 49 patients received DT LVADs. Nine patients were identified as myocardial recovery candidates using the protocol screening criteria. Overall, 11 patients underwent formal confirmatory testing for recovery, of which 10 were deemed recovered and underwent LVAD explant, defunctionalization, or transplantation. 37.5% of patients that had a concomitant coronary artery bypass during LVAD implantation achieved recovery. An equal proportion of ischemic and non-ischemic cardiomyopathy patients achieved recovery. The cumulative incidence of myocardial recovery was 25.1% at 36 months. No factors were identified as being predictive of recovery.

CONCLUSION

Myocardial recovery in DT LVAD patients can be achieved at a higher rate than previously reported. Revascularization at the time of LVAD is safe and may be beneficial. LVAD therapy may not be the final destination in these patients.

Trends and Outcomes of Left Ventricular Assist Device Therapy: JACC Focus Seminar

As the prevalence of advanced heart failure continues to rise, treatment strategies for select patients include heart transplantation or durable left ventricular assist device (LVAD) support, both of which improve quality of life and extend survival. Recently, the HeartMate 3 has been incorporated into clinical practice, the United Network for Organ Sharing donor heart allocation system was revised, and the management of LVAD-related complications has evolved. Contemporary LVAD recipients have greater preoperative illness severity, but survival is higher and adverse event rates are lower compared with prior eras. This is driven by advances in device design, patient selection, surgical techniques, and long-term management. However, bleeding, infection, neurologic events, and right ventricular failure continue to limit broader implementation of LVAD support. Ongoing efforts to optimize management of patients implanted with current devices and parallel development of next-generation devices are likely to further improve outcomes for patients with advanced heart failure.

Hemodynamic assessment and risk classification for successful weaning of Impella in patients with cardiogenic shock

BACKGROUND

Clinical predictors for successful weaning of patients from Impella heart pump have not been clarified. We aimed to elucidate the relationship between pulmonary artery catheter (PAC) parameters at the time of Impella weaning and subsequent outcomes.

METHODS

We enrolled consecutive patients who had received Impella for cardiogenic shock. PAC data were collected immediately before Impella weaning. Patients were classified as non-survivors if they died or required any mechanical circulatory support reintroduction within 30 days of weaning.

RESULTS

Of 81 patients enrolled, 61 underwent Impella weaning. Of these, 16 were non-survivors. Predictive indicators of non-survival were high pulmonary artery wedge pressure (PAWP; hazard ratio [HR] per 5 mmHg 1.97, 95% CI 1.35-2.80; p < 0.001), high mean pulmonary artery pressure (MPAP; HR per 5 mmHg 1.90, 1.38-2.58; p < 0.001), and low cardiac power output (CPO; HR per 0.1 Watts 0.71, 0.52-0.92; p = 0.006). Cutoff values of PAWP 20 mmHg, MPAP 22 mmHg, and CPO 0.59 Watts showed strong associations with 30-day non-survival risk (low risk 8% in patients with low PAWP and high CPO or 4% in patients with low MPAP and high CPO; high risk 100% in patients with high PAWP and low CPO or 82% in patients with high MPAP and low CPO).

CONCLUSIONS

PAWP or MPAP higher than the cutoff with CPO below the cutoff at Impella weaning were associated with worse outcomes. We proposed a risk classification model for successful Impella weaning using PAC.

Physiology of Continuous-Flow Left Ventricular Assist Device Therapy

The expanding use of continuous-flow left ventricular assist devices (CF-LVADs) for end-stage heart failure warrants familiarity with the physiologic interaction of the device with the native circulation. Contemporary devices utilize predominantly centrifugal flow and, to a lesser extent, axial flow rotors that vary with respect to their intrinsic flow characteristics. Flow can be manipulated with adjustments to preload and afterload as in the native heart, and ascertainment of the predicted effects is provided by differential pressure-flow (H-Q) curves or loops. Valvular heart disease, especially aortic regurgitation, may significantly affect adequacy of mechanical support. In contrast, atrioventricular and ventriculoventricular timing is of less certain significance. Although beneficial effects of device therapy are typically seen due to enhanced distal perfusion, unloading of the left ventricle and atrium, and amelioration of secondary pulmonary hypertension, negative effects of CF-LVAD therapy on right ventricular filling and function, through right-sided loading and septal interaction, can make optimization challenging. Additionally, a lack of pulsatile energy provided by CF-LVAD therapy has physiologic consequences for end-organ function and may be responsible for a series of adverse effects. Rheological effects of intravascular pumps, especially shear stress exposure, result in platelet activation and hemolysis, which may result in both thrombotic and hemorrhagic consequences. Development of novel solutions for untoward device-circulatory interactions will facilitate hemodynamic support while mitigating adverse events. © 2021 American Physiological Society. Compr Physiol 12:1-37, 2021.

Invasive Haemodynamic Assessment Before and After Left Ventricular Assist Device Implantation: A Guide to Current Practice

Mechanical circulatory support for the management of advanced heart failure is a rapidly evolving field. The number of durable long-term left ventricular assist device (LVAD) implantations increases each year, either as a bridge to heart transplantation or as a stand-alone ‘destination therapy’ to improve quantity and quality of life for people with end-stage heart failure. Advances in cardiac imaging and non-invasive assessment of cardiac function have resulted in a diminished role for right heart catheterisation (RHC) in general cardiology practice; however, it remains an essential tool in the evaluation of potential LVAD recipients, and in their long-term management. In this review, the authors discuss practical aspects of performing RHC and potential complications. They describe the haemodynamic markers associated with a poor prognosis in patients with left ventricular systolic dysfunction and evaluate the measures of right ventricular (RV) function that predict risk of RV failure following LVAD implantation. They also discuss the value of RHC in the perioperative period; when monitoring for longer term complications; and in the assessment of potential left ventricular recovery.

Left Ventricular Hemodynamics and Relationship with Myocardial Recovery and Optimization in Patients Supported on CF-LVAD Therapy

BACKGROUND

Despite interest in left ventricular (LV) recovery, there is an absence of data on the relationship between intrinsic LV hemodynamics and both reverse remodeling on continuous flow left ventricular assist device (CF-LVAD) therapy. We hypothesized that markers of intrinsic LV function would be associated with remodeling, optimization, and outcomes.

METHODS

Patients with continuous flow LVADs between 2015 and 2019 who underwent combined left and right heart catheterization (LHC/RHC) ramp protocol at a single institution were enrolled. Patients were stratified by response to CF-LVAD therapy: full responders (FR), partial responders (PR), or non-responders (NR) per Utah-Inova criteria. Hemodynamic data, including LV hemodynamics of peak LV dP/dt and tau (τ) were obtained at each phase. One-year heart failure hospitalization-free survival was the primary endpoint.

RESULTS

Among 61 patients included in the current study 38 (62%) were classified as NR, 14 (23%) PR, and 9 (15%) FR. Baseline LV dP/dt and τ varied by response status (P≤.02) and generally correlated with reverse remodeling on linear regression. Biventricular filling pressures varied with τ and there was an interaction effect of speed on the relationship between τ and PCWP (P=.04). Lastly, τ was a prognostic marker and associated with one-year HF-hospital free survival (OR 1.04, 95%CI 1.00-1.07, P=.02 per ms increase).

CONCLUSIONS

Significant correlations between τ and LV dP/dt and reverse remodeling were noted with tau serving as a prognostic marker. Higher LVAD speed was associated with a greater reliance on LVAD for unloading. Future work should focus on defining the optimal level of LVAD support in relation to LV recovery.

Manual zur Indikation und Durchführung spezieller echokardiographischer Anwendungen

Das zweite Manual zur Indikation und Durchführung der Echokardiographie bezieht sich auf spezifische Anwendungen der Echokardiographie und besondere Fragestellungen bei speziellen Patientengruppen. Dabei stehen v. a. praktische Aspekte im Vordergrund. Methodisch etabliert sind die transösophageale Echokardiographie, die Stressechokardiographie und die Kontrastechokardiographie. Bei nahezu allen echokardiographischen Untersuchungen spielen aktuell 3‑D-Echokardiographie und Deformationsbildgebung eine Rolle. Das gesamte Spektrum der echokardiographischen Möglichkeiten wird derzeit in Notfall- und Intensivmedizin, bei der Überwachung und Führung von Katheterinterventionen, bei strukturellen Herzerkrankungen, bei herzchirurgischen Operationen, bei der Nachsorge von kardialen Unterstützungssystemen, bei kongenitalen Vitien im Erwachsenenalter und bei der Versorgung von hochinfektiösen Patienten in Pandemiezeiten angewandt. Die diagnostischen Fortschritte der konventionellen und modernen echokardiographischen Anwendungen stehen im Fokus dieses Manuals. Die 3‑D-Echokardiographie zur Charakterisierung der kardialen Morphologie und die Deformationsbildgebung zur Objektivierung der kardialen Funktion sind bei vielen Indikationen im klinischen Alltag etabliert. Die Stressechokardiographie zur Ischämie‑, Vitalitäts- und Vitiendiagnostik, die Bestimmung der koronaren Flussreserve und die Kontrastechokardiographie bei der linksventrikulären Wandbewegungsanalyse und kardialen Tumordetektion finden zunehmend klinische Anwendung. Wie für die konventionelle Echokardiographie im ersten Manual der Echokardiographie 2009 beschrieben, erfordert der Einsatz moderner echokardiographischer Verfahren die standardisierte Dokumentation und Akquisition bestimmter Bildsequenzen bei optimierter Geräteeinstellung, da korrekte und reproduzierbare Auswertungen nur bei guter Bildqualität möglich sind.

Correlation between Myocardial Function and Electric Current Pulsatility of the Sputnik Left Ventricular Assist Device: In-Vitro Study

This study assesses the electric current parameters and reports on the analysis of the associated degree of myocardial function during left ventricular assist device (LVAD) support. An assumption is made that there is a correlation between cardiac output and the pulsatility index of the pump electric current. The experimental study is carried out using the ViVitro Pulse Duplicator System with Sputnik LVAD connected. Cardiac output and cardiac power output are used as a measure of myocardial function. Different heart rates (59, 73, 86 bpm) and pump speeds (7600–8400 rpm in 200 rpm steps) are investigated. In our methodology, ventricular stroke volumes in the range of 30–80 mL for each heart rate at a certain pump speed were used to simulate different levels of contractility. The correlation of the two measures of myocardial function and proposed pulsatility index was confirmed using different correlation coefficients (values ≥ 0.91). Linear and quadratic models for cardiac output and cardiac power output versus pulsatility index were obtained using regression analysis of measured data. Coefficients of determination for CO and CPO models were in the ranges of 0.914–0.982 and 0.817–0.993, respectively. Study findings suggest that appropriate interpretation of parameters could potentially serve as a valuable clinical tool to assess myocardial therapy using LVAD infrastructure.

The "TIDE"-Algorithm for the Weaning of Patients With Cardiogenic Shock and Temporarily Mechanical Left Ventricular Support With Impella Devices. A Cardiovascular Physiology-Based Approach

Objectives: Mechanical circulatory support (MCS) is often required to stabilize therapy-refractory cardiogenic shock patients. Left ventricular (LV) unloading by mechanical ventricular support (MVS) via percutaneous devices, such as with Impella® axial pumps, alone or in combination with extracorporeal life support (ECLS, ECMELLA approach), has emerged as a potential clinical breakthrough in the field. While the weaning from MCS is essentially based on the evaluation of circulatory stability of patients, weaning from MVS holds a higher complexity, being dependent on bi-ventricular function and its adaption to load. As a result of this, weaning from MVS is mostly performed in the absence of established algorithms. MVS via Impella is applied in several cardiogenic shock etiologies, such as acute myocardial infarction (support over days) or acute fulminant myocarditis (prolonged support over weeks, PROPELLA). The time point of weaning from Impella in these cohorts of patients remains unclear. We here propose a novel cardiovascular physiology-based weaning algorithm for MVS.

Methods: The proposed algorithm is based on the experience gathered at our center undergoing an Impella weaning between 2017 and 2020. Before undertaking a weaning process, patients must had been ECMO-free, afebrile, and euvolemic, with hemodynamic stability guaranteed in the absence of any inotropic support. The algorithm consists of 4 steps according to the acronym TIDE: (i) Transthoracic echocardiography under full Impella-unloading; (ii) Impella rate reduction in single 8–24 h-steps according to patients hemodynamics (blood pressure, heart rate, and ScVO₂), including a daily echocardiographic assessment at minimal flow (P2); (iii) Dobutamine stress-echocardiography; (iv) Right heart catheterization at rest and during Exercise-testing via handgrip. We here present clinical and hemodynamic data (including LV conductance data) from paradigmatic weaning protocols of awake patients admitted to our intensive care unit with cardiogenic shock. We discuss the clinical consequences of the TIDE algorithm, leading to either a bridge-to-recovery, or to a bridge-to-permanent LV assist device (LVAD) and/or transplantation. With this protocol we were able to wean 74.2% of the investigated patients successfully. 25.8% showed a permanent weaning failure and became LVAD candidates.

Conclusions: The proposed novel cardiovascular physiology-based weaning algorithm is based on the characterization of the extent and sustainment of LV unloading reached during hospitalization in patients with cardiogenic shock undergoing MVS with Impella in our center. Prospective studies are needed to validate the algorithm.

Experience with a standardized protocol to predict successful explantation of left ventricular assist devices

OBJECTIVE

Patients with a continuous-flow left ventricular assist device may show recovery of myocardial function with unloading. Identifying candidates for and predicting clinical and hemodynamic stability after left ventricular assist device explantation remain challenging.

METHODS

Retrospective analysis of patients who underwent evaluation for left ventricular assist device explantation following a standardized protocol from January 2016 to March 2020. Patients who met screening criteria underwent echocardiography under "baseline," "minimal net flow," and "pump stop" conditions. If the protocol criteria were met, right heart catheterization with left ventricular assist device stoppage and occlusion of the outflow graft with a balloon catheter were performed. In patients with pulmonary capillary wedge pressure less than 16 mm Hg, explantation was performed under "pump stop" conditions.

RESULTS

A total of 544 patients were screened. Of these, 57 (10.5%) underwent a total of 73 echocardiography under "baseline" "minimal net flow" and "pump stop" conditions and 46 underwent left ventricular assist device stoppage and occlusion of the outflow graft with balloon catheter maneuvers. Complications during the procedure were rare. Ultimately, 21 patients (3.9%) underwent explantation. The left ventricular ejection fraction at baseline was 55.5% ± 6.5%. The mean pulmonary capillary wedge pressure was 8.1 ± 2.6 mm Hg and increased to 10.7 ± 2.9 mm Hg under left ventricular assist device stoppage and occlusion of the outflow graft with a balloon catheter. A nonischemic cause of cardiomyopathy was more likely to be found in patients who underwent explantation (20/21 patients [95%], P = .020). The survival 1 year after explantation was 95.2%, with 1 death occurring 222 days after left ventricular assist device explantation. At follow-up (median 24.9 months [interquartile range, 16.4-43.1 months]), patients were in New York Heart Association class 1 (61.9%), 2 (28.6%), and 3 (9.5%).

CONCLUSIONS

Our 4-year experience with a standardized protocol for left ventricular assist device explantation showed a low rate of adverse events. If all criteria are met, explantation can be performed safely and with an excellent survival and functional class.

An advanced universal circulatory assist device for left and right ventricular support: First report of an acute in vivo implant

Background

The Advanced ventricular assist device (Advanced VAD) is designed as a universal pump intended to prevent backflow in the event of pump stoppage, to maintain physiological pulse pressure, and to be used as both a left and right VAD. The purpose of this study was to evaluate the performance of the Advanced VAD as both a left and right VAD in an acute in vivo study in calves.

Methods

The Advanced VAD was implanted through a median sternotomy in 5 healthy calves (weight, 71.4-91.2 kg) as a left VAD (n = 3) or a right VAD (n = 2). After implantation, hemodynamic parameters, including general performance and pump stoppage, were evaluated.

Results

The Advanced VAD was successfully implanted as a left and right VAD without cardiopulmonary bypass. The speed range of the Advanced VAD was 2500 to 3500 rpm as a left VAD and 2000 to 2500 rpm as a right VAD. Up to 4.3 L/min was achieved for both left and right VAD configurations. To demonstrate the automatic shut-off feature, the pump was stopped without clamping the outflow graft. The outflow graft was then clamped, which produced no significant changes in the arterial pressure waveform. The pulse pressures under the left VAD configuration were 38 mm Hg, 17 mm Hg, 14 mm Hg, and 16 mm Hg at baseline, 2500 rpm, 3000 rpm, and 3500 rpm, respectively.

Conclusions

This acute in vivo study demonstrated the pump performance, anatomical fitting as both left VAD and right VAD, and regurgitant flow shut-off feature of the Advanced VAD.

Outcomes of patients after successful left ventricular assist device explantation: a EUROMACS study

AIMS

Sufficient myocardial recovery with the subsequent explantation of a left ventricular assist device (LVAD) occurs in approximately 1-2% of the cases. However, follow-up data about this condition are scarcely available in the literature. This study aimed to report the long-term outcomes and clinical management following LVAD explantation.

METHODS AND RESULTS

An analysis of the European Registry for Patients with Mechanical Circulatory Support was performed to identify all adult patients with myocardial recovery and successful explantation. Pre-implant characteristics were retrieved and compared with the non-recovery patients. The follow-up data after explantation were collected via a questionnaire. A Kaplan-Meier analysis for freedom of the composite endpoint of death, heart transplantation, LVAD reimplantion, or heart failure (HF) relapse was conducted. A total of 45 (1.4%) cases with myocardial recovery resulting in successful LVAD explantation were identified. Compared with those who did not experience myocardial recovery, the explanted patients were younger (44 vs. 56 years, P < 0.001), had a shorter duration of cardiac disease (P < 0.001), and were less likely to have ischaemic cardiomyopathy (9% vs. 41.8%, P < 0.001). Follow-up after explantation could be acquired in 28 (62%) cases. The median age at LVAD implantation was 43 years (inter-quartile range: 29-52), and 23 (82%) were male. Baseline left ventricular ejection fraction was 18% (inter-quartile range: 10-20%), and 60.7% of the patients had Interagency Registry for Mechanically Assisted Circulatory Support Profile 1 or 2. Aetiologies of HF were dilated cardiomyopathy in 36%, myocarditis in 32%, and ischaemic in 14% of the patients, and 18% had miscellaneous aetiologies. The devices implanted were HeartMate II in 14 (50%), HVAD in 11 (39%), HeartMate 3 in 2 (7%), and 1 unknown with a median duration of support of 410 days (range: 59-1286). The median follow-up after explantation was 26 months (range 0.3-73 months), and 82% of the patients were in New York Heart Association Class I or II. Beta-blockers were prescribed to 85%, angiotensin-converting enzyme inhibitors to 71%, and loop diuretics to 50% of the patients, respectively. Freedom from the composite endpoint was 100% after 30 days and 88% after 2 years.

CONCLUSIONS

The survival after LVAD explantation is excellent without the need for heart transplantation or LVAD reimplantation. Only a minority of the patients suffer from a relapse of significant HF.