Induction of T-cell apoptosis by polyurethane biomaterials used in left ventricular assist devices is dependent on calcineurin activation

The Impact of Hypogammaglobulinemia on Infection Outcome in Patients Undergoing Ventricular Assist Device Implantation

BACKGROUND

Infection is a major comorbidity after ventricular assist device (VAD) placement. Defects in cellular immunity have been reported after VAD placement. However, to our knowledge, quantitative immunoglobulin G (IgG) level determination and the impact of hypogammaglobulinemia (HGG) on infections after VAD implantation have not been evaluated before.

METHODS

A total of 76 patients (mean age, 53 years) underwent VAD implantation as a bridge to transplantation and had IgG levels determined as a baseline before transplantation. Patients were divided into 2 groups according to IgG level: Control Group (n = 56, IgG > or = 700 mg/dl) and HGG Group (n = 20, IgG < 700 mg/dl). Infection outcome during the VAD course and after transplantation was analyzed in relation to the IgG level.

RESULTS

Baseline characteristics were similar in both groups. The incidence of bacteremia (14/20 [70%] vs 18/56 [32%], p = 0.0032) and major infection (19/20 [95%] vs 31/56 [56%], p = 0.0009) were significantly increased in the HGG Group compared with the Control Group. After transplantation, the episodes of rejection were similar in both groups and survival was similar. The HGG Group experienced more cytomegalovirus infections compared with the Control Group (9/20 [45%] vs 9/56 [16%], p = 0.009).

CONCLUSIONS

VAD patients with HGG are at increased risk of infections. After transplantation, these patients also experience increased cytomegalovirus infections. A randomized preemptive IgG replacement trial may be warranted in the future to determine if this intervention will alleviate the risk of infection.

Lack of sensitization and equivalent post-transplant outcomes with the Novacor left ventricular assist device

BACKGROUND

Ventricular assist devices (VADs) are increasingly used to support critically ill heart failure patients awaiting transplantation. Previous work has focused on the Thoratec Heartmate VE device, use of which is associated with pre-formed antibody production. We reviewed our cumulative experience with the Worldheart Novacor VAD as a bridge to transplantation (BTT).

METHODS

From January 1989 through October 2002, 39 patients required a VAD bridge, with 26 of 39 surviving to transplantation. Antibody levels were assessed by complement-dependent cytotoxicity assay at routine intervals and expressed as panel reactive antibody (PRA) levels. Post-transplant allograft rejection, coronary vasculopathy, and survival were compared between Novacor-supported patients and non-VAD transplant recipients.

RESULTS

PRA values did not significantly change after VAD implantation (12.4% +/- 11.2% vs 14.8% +/- 12.3%, p = 0.28). Survival for the BTT patients was 80.4%, 75.7%, 64.0%, 64.0%, and 64.0%, respectively, for 1, 3, 5, 7, and 10 years post-transplant, with similar results for non-BTT patients. The freedom from coronary vasculopathy was 90.2%, 90.2%, 72.2%, and 72.2%, respectively, at 1, 3, 5, and 7 years post-transplant.

CONCLUSIONS

First, to our knowledge, this study is the first to examine the incidence of allosensitization after Novacor implant in detail. In contrast with previous results of work with other VAD systems, as assessed by PRA levels, Novacor patients did not become sensitized. Second, compared with 220 non-BTT patients who received transplants during a similar time frame, Novacor BTT patients had equivalent rejection profiles and survival. Finally, the incidence of transplant-associated coronary artery disease was lower than in previous reports.

Managing Device Infections: Are We Progressing or Is Infection an Insurmountable Obstacle?

This article reviews infections that occur in patients with implanted mechanical circulatory support devices and presents recent data for signs of progress in controlling the incidence and impact of these infections. Two types of comparisons are used to examine this question. First, the outcomes of patients with HeartMate vented electric left ventricular assist devices (VADs) (Thoratec Corp, Pleasanton, CA) implanted during the REMATCH Trial are compared with the outcome of more recent patients who received this pump as destination therapy. Second, the outcome of patients who received a smaller left VAD (e.g., an axial flow VAD) or a fully implanted left VAD are reported and contrasted with results from the REMATCH era. Data are presented to support the hypothesis that improvements in patient selection, patient management, device durability, and device design have resulted in lower rates of infection and infection-related death for patients who require mechanical circulatory support.

L'activation sanguine au cours de l'assistance circulatoire mécanique prolongée

Mechanical circulatory support has become an approved treatment option for patients with cardiogenic shock or end-stage heart failure. However, recipients of heart assist devices are prone to high incidences of bleeding, thrombo-embolic and infectious complications. The occurrence of these complications is favoured by systemic alterations of coagulation and fibrinolysis, inflammation and immune responses. Several studies have evaluated these pathophysiological changes in patients undergoing long term circulatory support with pulsatile devices. However, the systemic consequences of the more recently introduced rotary blood pumps remain largely unknown. The present review focuses on the systemic consequences of long term circulatory support with pulsatile and non-pulsatile devices.

Nonvalvular Intravascular Device-related Infections

Nonvalvular intravascular devices are in widespread use in developed countries and are now more commonly employed than are prosthetic cardiac valves. Although the variety of devices that are included in the category of "nonvalvular" represent a heterogenous collection, there is commonality among several of the devices. This includes their requirement to sustain life and the need for removal for cure if they become infected, which is often due to multidrug-resistant microorganisms. Thus, infection of these devices often presents difficult treatment scenarios. This update will address the pathogenesis and immunobiology of nonvalvular intravascular device-related infections and the epidemiology and treatment of infections of several of these devices that include pacemakers, implantable cardioverter defibrillators, intravascular catheters, vascular grafts and stents, and left ventricular assist devices.