Continuous-flow devices and percutaneous site infections: clinical outcomes

State of the art of mechanical circulatory support

Mechanical circulatory support of the failing heart has become an important means of treating end-stage heart disease. This rapidly growing therapeutic field has produced impressive clinical outcomes and has great potential to help thousands of otherwise terminal patients worldwide. In this review, we examine the state of the art of mechanical circulatory support: current practice, totally implantable systems of the future, evolving biventricular support mechanisms, the potential for myocardial recovery and adjunctive treatment methods, and miniaturized devices with expanded indications for therapy.

Clinical outcomes associated with chronic antimicrobial suppression therapy in patients with continuous-flow left ventricular assist devices

This retrospective cohort study evaluates the effect of chronic antimicrobial suppression (CAS) therapy on clinical outcomes in patients with continuous-flow left ventricular assist devices (CF-LVADs) and a history of device-related infection. Patients with CF-LVAD implantation between January 2008 and August 2011 who received systemic CAS after index antibiotic treatment of a device-related infection were included. Chronic suppression was defined as continuation of antibiotics for longer than 6 weeks after the index infection. Standard International Society for Heart and Lung Transplantation definitions were used. The primary outcome is failure of CAS, defined as a clinical deterioration resulting in the need for transition from oral to intravenous (IV) therapy or a need to change to a different IV antibiotic, elevation to status 1A on the transplant list as a result of ongoing infection, or device/driveline exchange. Of 140 patients screened, 16 patients were included (69% male, 63% African American, median age 52 years). The driveline was the most common site of infection (69%). Organisms isolated included Gram-positive cocci (n = 7), Gram-negative bacilli (n = 10), and Candida (n = 1). Oral trimethoprim/sulfamethoxazole treatment was most commonly used for suppression (37.5%). Failure of CAS occurred in 5/16 (31%) patients after a mean time of 175 days on therapy (range 10-598). The majority of failures (60%) required device exchanges. Side effects of nausea, vomiting, or diarrhea were reported in three patients; all required changes in oral suppression regimen. Clostridium difficile infection was noted in two patients. These results, which must be confirmed by a larger analysis, suggest that one-third of CF-LVAD patients may develop recurrent infections while on CAS therapy.

Dosing of Vancomycin in Patients with Continuous-Flow Left Ventricular Assist Devices: A Clinical Pharmacokinetic Analysis

Purpose

To describe the pharmacokinetics of vancomycin in patients with continuous-flow left ventricular assist devices (CF-LVADs).

Methods

Eligible patients were ≥18 years old, implanted with a Heart Mate II CF-LVAD during January 2008-April 2012, and treated with vancomycin ≥48 hours for infection. Key exclusion criteria were unstable renal function, acute heart failure exacerbation, hemodynamic instability, and recent surgery. First-order elimination rate constant (Ke) and volume of distribution (Vd) were estimated using ideal (IBW), adjusted (AdjBW), actual (ABW), and fixed body weights. Estimated parameters were compared with measured pharmacokinetic parameters, which were calculated from steady state peak and trough vancomycin levels using one-compartment model equations.

Results

Twelve patients were included (age 44.9 ± 15 years, 91.7% male, 58.3% obese, CLcr 79.2 ± 27 mL · min-1). Common treatment indications were health-care associated pneumonia (41.7%), driveline infection (25%), and sepsis (16.7%). All methods of predicting Ke provided overestimates (p<0.05), ranging from 47 to 79%, depending on body habitus. Methods of predicting Vd using ABW in obese patients yielded overestimates of 74.5% (p<0.05), where IBW predictive Vd equations provided accurate assessments regardless of body habitus.

Conclusions

General population methods may not accurately estimate the pharmacokinetic parameters of vancomycin for compensated heart failure patients implanted with CF-LVADs.

A simple device to secure ventricular assist device driveline and prevent exit-site infection

OBJECTIVES

Driveline infections are one of the most common and important complications in patients with left ventricular assist device (LVAD). One of the causes favouring the development of this complication is the traumatism of the exit site, which occurs in response to movement of the driveline. In this work, we present a simple and feasible method to immobilize the driveline at the level of the exit site.

METHODS

From April 2013 until November 2013, 6 patients underwent implantation of HeartWare LVAD (HVAD) for an end-stage heart failure. When the patient has begun to mobilize after the implantation of the device, we have combined the use of two components with the aim of securing the driveline to the patient's skin: a StatLock system and a silicone suture.

RESULTS

No case of local traumatism and no case of local infection at the driveline were observed during the follow-up. No patient reported pain or swelling at the driveline exit site. All patients were satisfied with their quality-of-life and they do not report any limitations in their daily activities.

CONCLUSIONS

One of the major long-term complications in patients with LVAD is the development of infections of the exit site of the driveline. The trauma of this skin region promotes the onset and maintenance of an inflammatory process and local infectious. Avoiding excessive mobilization of the driveline is likely to reduce the incidence of infections of the exit site and improve the quality-of-life.

Infectious Complications of Mechanical Circulatory Support (MCS) Devices

Left-ventricular assist devices and other forms of mechanical circulatory support are increasingly important in the routine therapy of patients with end-stage congestive heart failure. Technology may help to decrease the rate of infections associated with these devices, but with larger numbers of implants being utilized across the globe, infections overall are becoming more commonplace. Becoming familiar with appropriate techniques for prevention and with the ideal approach to diagnostic and therapeutic strategies is key to managing mechanical circulatory support infections in this unique, but growing, patient population.

Impact of adverse events on ventricular assist device outcomes

Left ventricular assist devices have been proven to be superior to medical therapy for advanced heart failure patients awaiting heart transplantation and viable alternatives to transplantation for destination therapy patients. Improvements in the design of ventricular assist devices have been rewarded by a decrease in adverse events and an increase in survival. Despite significant progress, even the latest generation left ventricular assist devices are burdened by a significant long-term adverse events profile that will increasingly challenge physicians as patients survive longer on implantable mechanical circulatory support. In this review, we analyze the impact of long-term adverse events on clinical outcomes in the major trials of continuous flow left ventricular assist devices. We discuss several of the more pertinent and interesting adverse events, examine their potential causes, and explore their future implications.