Mechanical ventricular assistance in heart failure: pathology of the cardiac apex removed during device implantation

Diagnostic Usefulness of Histological Examination of the Left Ventricular "Core" Excised to Insert a Left Ventricular Assist Device in Patients With Severe Heart Failure

The left ventricular assist device (LVAD) has proven to be beneficial for patients with severe heart failure poorly responsive to anti heart failure medicine. To examine both grossly and histologically the portion of left ventricular (LV) free wall excised ("the left ventricular core") to insert a LVAD in 337 patients with severe heart failure from a variety of causes. We collected together all photographs of LV "cores" and the histologic sections prepared from them and reexamined both. Despite the fact that these LV cores usually weighed >100 times the quantity of myocardium available to examine compared with that available by biotome inserted via a transvenous catheter, the number in which histologic study allowed an unequivocal diagnosis was limited. Examination of the clinical records usually was required to establish the definitive diagnosis. Although the presence of a scarred myocardial wall usually suggested ischemic cardiomyopathy (IC), the scarring may not have involved the LV apex resulting in a nonscarred portion of myocardium simulating idiopathic dilated cardiomyopathy (IDC). Moreover, about 10% of the patients with IDC have myocardial scars thus simulating IC. Involvement of the LV core by amyloid, sarcoid, myocarditis, and acute infarction, of course, allowed a specific anatomic diagnosis. Despite the presence of ample tissue to secure a definitive diagnosis, the combination of clinical input and morphologic assessment was required to arrive at a definite diagnosis in most patients.

Myofibrillolysis and fibrosis predicts myocardial insufficiency

Introduction

Cardiocyte myofibrillolysis and interstitial fibrosis belong to histopathological changes in cardiomyopathies, leading to heart failure.

Aim

To evaluate these changes in apical resection during left ventricular assist device (LVAD) implantation.

Material and methods

The studied group consisted of 40 patients with cardiomyopathy, and apical samples excised during left ventricular assist device implantation were studied (CM/VAD group, mean: 48.1 ±10 y/o). A control group consisted of 6 apical samples from healthy heart graft donors (mean: 29 ±2.3 years old). Area fraction (AF) was calculated for: fibrosis, cardiocytes with myofibrillolysis (MFL), non-myofibrillolytic cardiocytes (non-MFL).

Results

Single lymphocytes were seen in 18 (45%) cases in the CM/VAD group. Cardiomyopathy grade evaluated semiquantitatively in CM/VAD was: slight (25% of a group), moderate (35.5%), advanced (35.5%). CM/VAD cases showed nearly ten times higher fibrosis than the control group. The MFL cells occupied nearly a five times larger area in CM/VAD than in the control group, whereas non-MFL cells were found in the control group, as a predominant pattern. The linear regression calculated between fibrosis AF and types of cardiocytes indicated the depletion of cardiomyocytes with fibrosis increase. The control group presented insignificant dependency between fibrosis and MFL cells, suggesting the lack of replacement fibrosis. Significant negative dependence between fibrosis and non-MFL cardiocytes suggested remodeling in controls. Correlation analysis showed a strong relation between depletion of normal cardiocytes and progression of fibrosis.

Conclusions

Progression of cardiomyopathy and fibrosis depends on the loss of cardiocytes rather than degeneration of these cells.

Advanced iron-overload cardiomyopathy in a genetic murine model is rescued by resveratrol therapy

Iron-overload cardiomyopathy is prevalent on a worldwide basis and is a major comorbidity in patients with genetic hemochromatosis and secondary iron overload. Therapies are limited in part due to lack of a valid preclinical model, which recapitulates advanced iron-overload cardiomyopathy. Male hemojuvelin (HJV) knockout (HJVKO) mice, which lack HJV, a bone morphogenetic co-receptor protein required for hepcidin expression and systemic iron homeostasis, were fed a high-iron diet starting at 4 weeks of age for a duration of 1 year. Aged HJVKO mice in response to iron overload showed increased myocardial iron deposition and mortality coupled with oxidative stress and myocardial fibrosis culminating in advanced iron-overload cardiomyopathy. In a parallel group, iron-overloaded HJVKO mice received resveratrol (240 mg/day) at 9 months of age until 1 year of age. Echocardiography and invasive pressure–volume (PV) loop analyses revealed a complete normalization of iron-overload mediated diastolic and systolic dysfunction in response to resveratrol therapy. In addition, myocardial sarcoplasmic reticulum Ca²⁺ ATPase (SERCa2a) levels were reduced in iron-overloaded hearts and resveratrol therapy restored SERCa2a levels and suppressed up-regulation of the sodium–calcium exchanger (NCX1). Further, iron-mediated oxidative stress and myocardial fibrosis were suppressed by resveratrol treatment with concomitant activation of the p-Akt and p-AMP-activated protein kinase (AMPK) signaling pathways. A combination of ageing and high-iron diet in male HJVKO mice results in a valid preclinical model that recapitulates iron-overload cardiomyopathy in humans. Resveratrol therapy resulted in normalization of cardiac function demonstrating that resveratrol represents a feasible therapeutic intervention to reduce the burden of iron-overload cardiomyopathy.

Refractory cardiogenic shock in a patient with β-thalassemia major requiring mechanical circulatory support: Case report and literature review

Iron overload cardiomyopathy secondary to β-thalassemia major is a potentially reversible condition managed with chelation and medical hemodynamic support, as bridge-to-recovery or transplant. We describe our experience, and challenges faced, in a pediatric patient with iron overload cardiomyopathy secondary to β-thalassemia major, requiring biventricular MCS.

Presentation, diagnosis, and medical management of heart failure in children: Canadian Cardiovascular Society guidelines

Pediatric heart failure (HF) is an important cause of morbidity and mortality in childhood. This article presents guidelines for the recognition, diagnosis, and early medical management of HF in infancy, childhood, and adolescence. The guidelines are intended to assist practitioners in office-based or emergency room practice, who encounter children with undiagnosed heart disease and symptoms of possible HF, rather than those who have already received surgical palliation. The guidelines have been developed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and are accompanied by practical Recommendations for their application in the clinical setting, supplemented by online material. This work does not include Recommendations for advanced management involving ventricular assist devices, or other device therapies.

The chemokine decoy receptor D6 prevents excessive inflammation and adverse ventricular remodeling after myocardial infarction

OBJECTIVE

Leukocyte infiltration in ischemic areas is a hallmark of myocardial infarction, and overwhelming infiltration of innate immune cells has been shown to promote adverse remodeling and cardiac rupture. Recruitment of inflammatory cells in the ischemic heart depends highly on the family of CC-chemokines and their receptors. Here, we hypothesized that the chemokine decoy receptor D6, which specifically binds and scavenges inflammatory CC-chemokines, might limit inflammation and adverse cardiac remodeling after infarction.

METHODS AND RESULTS

D6 was expressed in human and murine infarcted myocardium. In a murine model of myocardial infarction, D6 deficiency led to increased chemokine (C-C motif) ligand 2 and chemokine (C-C motif) ligand 3 levels in the ischemic heart. D6-deficient (D6(-/-)) infarcts displayed increased infiltration of pathogenic neutrophils and Ly6Chi monocytes, associated with strong matrix metalloproteinase-9 and matrix metalloproteinase-2 activities in the ischemic heart. D6(-/-) mice were cardiac rupture prone after myocardial infarction, and functional analysis revealed that D6(-/-) hearts had features of adverse remodeling with left ventricle dilation and reduced ejection fraction. Bone marrow chimera experiments showed that leukocyte-borne D6 had no role in this setting, and that leukocyte-specific chemokine (C-C motif) receptor 2 deficiency rescued the adverse phenotype observed in D6(-/-) mice.

CONCLUSIONS

We show for the first time that the chemokine decoy receptor D6 limits CC-chemokine-dependent pathogenic inflammation and is required for adequate cardiac remodeling after myocardial infarction.

Ethical challenges with deactivation of durable mechanical circulatory support at the end of life: left ventricular assist devices and total artificial hearts

Left ventricular assist devices (LVADs) and total artificial hearts (TAHs) are surgically implanted as permanent treatment of unrecoverable heart failure. Both LVADs and TAHs are durable mechanical circulatory support (MCS) devices that can prolong patient survival but also alter end-of-life trajectory. The permissibility of discontinuing assisted circulation is controversial because device deactivation is a life-ending intervention. Durable MCS is intended to successfully replace native physiological functions in heart disease. We posit that the presence of new lethal pathophysiology (ie, a self-perpetuating cascade of abnormal physiological processes causing death) is a central element in evaluating the permissibility of deactivating an LVAD or a TAH. Consensual discontinuation of durable MCS is equivalent with allowing natural death when there is an onset of new lethal pathophysiology that is unrelated to the physiological functions replaced by an LVAD or a TAH. Examples of such lethal conditions include irreversible coma, circulatory shock, overwhelming infections, multiple organ failure, refractory hypoxia, or catastrophic device failure. In all other situations, deactivating the LVAD/TAH is itself the lethal pathophysiology and the proximate cause of death. We postulate that the onset of new lethal pathophysiology is the determinant factor in judging the permissibility of the life-ending discontinuation of a durable MCS.