Myocardial recovery in patients with chronic heart failure: is it real?

Myocardial Recovery

In this paper, the feasibility of myocardial recovery is analyzed through a literature review. First, the phenomena of remodeling and reverse remodeling are analyzed, approached through the physics of elastic bodies, and the terms myocardial depression and myocardial recovery are defined. Continuing, potential biochemical, molecular, and imaging markers of myocardial recovery are reviewed. Then, the work focuses on therapeutic techniques that can facilitate the reverse remodeling of the myocardium. Left ventricular assist device (LVAD) systems are one of the main ways to promote cardiac recovery. The changes that take place in cardiac hypertrophy, extracellular matrix, cell populations and their structural elements, β-receptors, energetics, and several biological processes, are reviewed. The attempt to wean the patients who experienced cardiac recovery from cardiac assist device systems is also discussed. The characteristics of the patients who will benefit from LVAD are presented and the heterogeneity of the studies performed in terms of patient populations included, diagnostic tests performed, and their results are addressed. The experience with cardiac resynchronization therapy (CRT) as another way to promote reverse remodeling is also reviewed. Myocardial recovery is a phenomenon that presents with a continuous spectrum of phenotypes. There is a need for algorithms to screen suitable patients who may benefit and identify specific ways to enhance this phenomenon in order to help combat the heart failure epidemic.

Cardiac Muscle Training-A New Way of Recognizing and Supporting Recovery for LVAD Patients in the Pediatric Population

Patients with refractory heart failure due to chronic progressive cardiac myopathy (CM) may require mechanical circulatory support as a bridge to transplantation. A few patients can be weaned from support devices if recovery can be achieved. The identification of these patients is of great importance as recovery may be missed if the heart is unloaded by the ventricular assist device (VAD). Testing the load-bearing capacity of the supported left ventricle (LV) by temporarily and gradually reducing mechanical support during cardiac exercise can help identify responders and potentially aid the recovery process. An exercise training protocol was used in 3 patients (8 months, 18 months and 8 years old) with histological CM findings and myocarditis. They were monitored regularly using clinical information and functional imaging with VAD support. Echocardiographic examination included both conventional real-time 3D echocardiography (RT3DE) and speckle tracking (ST). A daily temporary reduction in pump rate (phase A) was followed by a permanent reduction in rate (phase B). Finally, pump stops of up to 30 min were performed once a week (phase C). The final decision on explantation was based on at least three pump stops. Two patients were weaned and successfully removed from the VAD. One of them was diagnosed with acute viral myocarditis. The other had chronic myocarditis with dilated myopathy and mild interstitial fibrosis. The noninvasive assessment of cardiac output and strain under different loading conditions during VAD therapy is feasible and helps identify candidates for weaning despite severe histological findings. The presented protocol, which incorporates new echocardiographic techniques for determining volume and deformation, can be of great help in positively guiding the process of individual recovery, which may be essential for selecting and increasing the number of patients to be weaned from VAD.

Heart failure in the young: Insights into myocardial recovery with ventricular assist device support

Background

Data on ventricular unloading-promoted myocardial recovery and post-weaning outcome in children is scarce. We analyzed the weaning outcome in children with heart failure (HF) supported with ventricular assist device (VAD).

Methods

A multi-institutional data on VAD implanted in 193 children and adolescents with HF between April 1990 and November 2015 was reviewed. Among them, 25 children (mean age 3.4±3.0, range, 0.058-16.3 years, 15 females) were weaned from VAD. Etiology of HF were myocarditis (n=11), dilated cardiomyopathy (DCMP) (n=7), ischemic HF (n=3), arrhythmogenic CMP (n=1), post-correction of congenital heart disease (CHD) (n=1) and acute graft failure (n=1). Mean duration of HF before VAD implantation was 59.4±3 days.

Results

Age, duration of HF, DCMP, cardiac arrest and duration of VAD are essential clinical characteristics to delineate who may have the potential to myocardial recovery. Echocardiographic parameters pre-implantation, during the final off-pump trial and during the post-explantation follow-ups revealed that LVEF, LVEDD and relative wall thickness (RWT) showed significant differences (P<0.001) among patients stratified by outcome to assess recovery. Presently, 21 (84.0%) of the weaned patients are alive with their native hearts 1.3-19.1 years after VAD explantation. An additional weaned patient had HF recurrence 3 months post-weaning and was transplanted.

Conclusions

Post-weaning myocardial recovery and cardiac stability of children with HF from several etiologies supported with a VAD appears sustainable and durable. Young patients with short HF duration are more likely to recover. Absence of cardiac arrest, cardiac size, geometry and function may prospectively identify patients who may be likely to have myocardial recovery.

Left Ventricular Assist Device as a Bridge to Recovery for Patients With Advanced Heart Failure

BACKGROUND

Left ventricular assist devices (LVADs) have been used as an effective therapeutic option in patients with advanced heart failure, either as a bridge to transplantation, as destination therapy, or in some patients, as a bridge to recovery.

OBJECTIVES

This study evaluated whether patients undergoing an LVAD bridge-to-recovery protocol can achieve cardiac and physical functional capacities equivalent to those of healthy controls.

METHODS

Fifty-eight male patients-18 implanted with a continuous-flow LVAD, 16 patients with LVAD explanted (recovered patients), and 24 heart transplant candidates (HTx)-and 97 healthy controls performed a maximal graded cardiopulmonary exercise test with continuous measurements of respiratory gas exchange and noninvasive (rebreathing) hemodynamic data. Cardiac function was represented by peak exercise cardiac power output (mean arterial blood pressure × cardiac output) and functional capacity by peak exercise O₂ consumption.

RESULTS

All patients demonstrated a significant exertional effort as demonstrated with the mean peak exercise respiratory exchange ratio >1.10. Peak exercise cardiac power output was significantly higher in healthy controls and explanted LVAD patients compared with other patients (healthy 5.35 ± 0.95 W; explanted 3.45 ± 0.72 W; LVAD implanted 2.37 ± 0.68 W; and HTx 1.31 ± 0.31 W; p < 0.05), as was peak O₂ consumption (healthy 36.4 ± 10.3 ml/kg/min; explanted 29.8 ± 5.9 ml/kg/min; implanted 20.5 ± 4.3 ml/kg/min; and HTx 12.0 ± 2.2 ml/kg/min; p < 0.05). In the LVAD explanted group, 38% of the patients achieved peak cardiac power output and 69% achieved peak O₂ consumption within the ranges of healthy controls.

CONCLUSIONS

The authors have shown that a substantial number of patients who recovered sufficiently to allow explantation of their LVAD can even achieve cardiac and physical functional capacities nearly equivalent to those of healthy controls.

Paediatric mechanical circulatory support with Berlin Heart EXCOR: development and outcome of a 23-year experience

This paper reviews the development and establishment of the Berlin Heart EXCOR® (BHE®) as a paediatric mechanical circulatory support and reports our entire experience with regard to indications, timing of implantation and explantation and outcome. The Berlin group reported the first successful paediatric bridge to transplantation using a pulsatile pneumatic paracorporeal biventricular assist device, the BHE®, in 1990 in an 8-year-old boy with end-stage heart failure and coarctation of the aorta. This experience prompted them to develop miniaturized pump systems for children through the company Berlin Heart Mediproduct GmbH. The development and production of BHE® to support paediatric patients with heart failure then began. Between 1990 and 2013, the BHE® has been implanted in 122 patients (median age 8.64 years, range 3 days to 17 years) with heart failure, who were inotrope-dependent or switched from extracorporeal membrane oxygenation support or had postcardiotomy low-output syndrome. Thirty-five patients were <1 year old (median 125 days). The aetiology of heart failure included cardiomyopathy in 56 (median age 9.14 years), fulminant myocarditis in 17 (median age 8.2 years), end-stage congenital heart disease in 18 (median age 6.4 years), postcardiotomy heart failure (after correction of congenital heart disease) in 28 (median age 9.6 years) and transplant graft failure in 3 (median age 12.5 years). The overall median duration of implantation was 63.6 (range 1-841) days. Fifty-six children eventually underwent orthotopic heart transplantation. Eighteen patients had myocardial recovery and were weaned successfully. They had entirely normal cardiac function after a range of 4-10 years after surgery. At the time of this report, five patients were still on support, with a duration of 354-369 days. Forty-three patients died on the system from loss of peripheral circulatory resistance, multiorgan damage, sepsis or haemorrhagic or thrombotic complications. Re-exploration because of bleeding was necessary in 22 patients. Pump exchange because of thrombus formation in the valves was necessary 35 times. With the introduction of a modified anticoagulation regimen in 2000, the pump exchange rate has decreased. The BHE® can reliably support the circulation at any age for long periods with good results. It is now an established treatment for children with heart failure of any aetiology.

Fibrosis and heart failure

The extracellular matrix (ECM) is a living network of proteins that maintains the structural integrity of the myocardium and allows the transmission of electrical and mechanical forces between the myocytes for systole and diastole. During ventricular remodeling, as a result of iterations in the hemodynamic workload, collagen, the main component of the ECM, increases and occupies the areas between the myocytes and the vessels. The resultant fibrosis (reparative fibrosis) is initially a compensatory mechanism and may progress adversely influencing tissue stiffness and ventricular function. Replacement fibrosis appears at sites of previous cardiomyocyte necrosis to preserve the structural integrity of the myocardium, but with the subsequent formation of scar tissue and widespread distribution, it has adverse functional consequences. Continued accumulation of collagen impairs diastolic function and compromises systolic mechanics. Nevertheless, the development of fibrosis is a dynamic process wherein myofibroblasts, the principal cellular elements of fibrosis, are not only metabolically active and capable of the production and upregulation of cytokines but also have contractile properties. During the process of reverse remodeling with left ventricular assist device unloading, cellular, structural, and functional improvements are observed in terminal heart failure patients. With the advent of anti-fibrotic pharmacologic therapies, cellular therapy, and ventricular support devices, fibrosis has become an important therapeutic target in heart failure patients. Herein, we review the current concepts of fibrosis as a main component of ventricular remodeling in heart failure patients. Our aim is to integrate the histopathologic process of fibrosis with the neurohormonal, cytochemical, and molecular changes that lead to ventricular remodeling and its physiologic consequences in patients. The concept of fibrosis as living scar allows us to envision targeting this scar as a means of improving ventricular function in heart failure patients.

Ventricular assist devices: initial orientation

Ventricular assist device (VAD) technology has come from large pulsatile-flow devices with a high rate of technical malfunctions to small continuous flow (cf) devices. Mechanical circulatory support (MCS) systems may be used as short-, mid- or long-term support. Especially if mid- or long-term support is anticipated left VADs (LVADs) have been reported with excellent one and two year survival rates and improved quality of life (QoL). Timing of implantation, patient selection, assessing function of the right ventricular and surgical considerations regarding surgical access side, valve pathology and exit side of the percutaneous lead remain crucial issues for the outcome. In contrast VADs designed for children especially for all age groups, are still underrepresented but increased experience with existing pediatric VADs as well as introduction of second and third generation VADs into in the pediatric age group, offer new perspectives.

Magnitude and time course of changes induced by continuous-flow left ventricular assist device unloading in chronic heart failure: insights into cardiac recovery

OBJECTIVES

This study sought to prospectively investigate the longitudinal effects of continuous-flow left ventricular assist device (LVAD) unloading on myocardial structure and systolic and diastolic function.

BACKGROUND

The magnitude, timeline, and sustainability of changes induced by continuous-flow LVAD on the structure and function of the failing human heart are unknown.

METHODS

Eighty consecutive patients with clinical characteristics consistent with chronic heart failure requiring implantation of a continuous-flow LVAD were prospectively enrolled. Serial echocardiograms (at 1, 2, 3, 4, 6, 9, and 12 months) and right heart catheterizations were performed after LVAD implant. Cardiac recovery was assessed on the basis of improvement in systolic and diastolic function indices on echocardiography that were sustained during LVAD turn-down studies.

RESULTS

After 6 months of LVAD unloading, 34% of patients had a relative LV ejection fraction increase above 50% and 19% of patients, both ischemic and nonischemic, achieved an LV ejection fraction ≥ 40%. LV systolic function improved as early as 30 days, the greatest degree of improvement was achieved by 6 months of mechanical unloading and persisted over the 1-year follow up. LV diastolic function parameters also improved as early as 30 days after LVAD unloading, and this improvement persisted over time. LV end-diastolic and end-systolic volumes decreased as early as 30 days after LVAD unloading (113 vs. 77 ml/m(2), p < 0.01, and 92 vs. 60 ml/m(2), p < 0.01, respectively). LV mass decreased as early as 30 days after LVAD unloading (114 vs. 95 g/m(2), p < 0.05) and continued to do so over the 1-year follow-up but did not reach values below the normal reference range, suggesting no atrophic remodeling after prolonged LVAD unloading.

CONCLUSIONS

Continuous-flow LVAD unloading induced in a subset of patients, both ischemic and nonischemic, early improvement in myocardial structure and systolic and diastolic function that was largely completed within 6 months, with no evidence of subsequent regression.

Cerebral blood flow as a marker for recovery of left ventricular systolic dysfunction in patients with idiopathic dilated cardiomyopathy

BACKGROUND

This study was intended to investigate whether cerebral blood flow (CBF) could predict the recovery of left ventricular (LV) systolic dysfunction in patients with idiopathic dilated cardiomyopathy (DCMP).

METHODS AND RESULTS

Between July 2001 and March 2009, 107 patients who had been diagnosed with idiopathic DCMP underwent radionuclide angiography to assess their CBF. The recovery of LV systolic dysfunction was defined as recovery of the ejection fraction (EF) measured by transthoracic echocardiography to a level of 40% or greater and an increase of 10% or greater in its absolute value during follow-up. The EF was followed for at least 36 months if it did not recover. Thirty-four patients (31.8%) recovered and had greater CBF than the nonrecovered patients (41.9 ± 3.4 vs. 37.1 ± 4.9 mL/min/100g, P < .001). On multivariate logistic analysis, CBF (odds ratio 1.216) and symptom duration (odds ratio 0.952) were independent predictors of the recovery of LV systolic dysfunction. There was also a weak negative correlation between CBF and symptom duration (r = -0.334, P < .001). Furthermore, CBF was associated with LVEF improvement seen at the 1- and 2-year follow-up times according to multiple linear regression analysis.

CONCLUSIONS

CBF was associated with recovery of LV systolic dysfunction in patients with idiopathic DCMP. Therefore, measurement of CBF would be helpful to predict the clinical course of their disease.

Pathologic Evaluation of Cardiovascular Medical Devices

Cardiovascular devices such as coronary artery stents, ventricular assist devices, pacemakers, automated implantable cardioverter-defibrillators and septal closure devices are life saving and improve quality of life for millions of patients each year. Complications of these devices include thrombosis/thromboembolism, infection, structural failure and adverse material-tissue interactions. These findings should be sought when these devices are encountered on the surgical pathology bench or at autopsy.

Successful weaning and explantation of the Heartmate II left ventricular assist device

BACKGROUND

Ventricular assist devices (VADs) are used in cases of heart failure refractory to medical therapy. Most VADs are used as a bridge to heart transplantation; however, in certain cases, myocardial function recovers and VADs can be explanted after the patient is weaned. The objectives of this study were to describe patients who required Heartmate II VAD insertion, followed by myocardial recovery and explanation in a quaternary heart centre.

METHODS

Patients who had a VAD explanted were identified in the mechanical support institutional database and their outcomes were analyzed. Clinical examinations, biochemical markers, and serial echocardiograms were used to demonstrate myocardial recovery.

RESULTS

Seventeen patients had a Heartmate II VAD inserted between 2008 and 2010. Four patients underwent successful weaning and subsequent VAD explantation. Etiology of decompensated heart failure was idiopathic dilated cardiomyopathy (n = 1), ischemic (n = 1), or myocarditis (n = 2). Mean age was 35.3 years. Patients were supported for 213 days (range 70-293 days) and were in New York Heart Association class I in the community before explantation. The devices were explanted via a minimally invasive approach, without cardiopulmonary bypass. All patients survived explantation and were discharged alive from hospital after an average of 5.7 ± 1.5 days post pump explantation. No adverse events were reported after explantation. Only one patient required allogenic blood transfusion after the procedure.

CONCLUSIONS

Patients requiring VAD support for myocardial failure can undergo significant reverse remodelling. Explantation can lead to optimal outcome with minimal morbidity. Methods for assessment of reverse remodelling, weaning protocol, and optimal timing of explantation remain under evaluation.

[Nonunion of the femoral neck and artificial heart. How far may we go?]

Due to medical improvements surgeons are increasingly confronted with conditions associated with severe medical comorbidities. Fracture or nonunion of the femoral neck would have been classified as "inoperable" in the past. We report the successful operative treatment of a patient with femoral neck nonunion after screw osteosynthesis and associated existence of a left ventricular assist device for dilated cardiomyopathy.