FDG-PET for the detection of infection in left ventricle assist device: Is there light at the end of the tunnel?

Abstract

LEFT VENTRICULAR ASSIST DEVICESOver the past decade, the use of continuous-flow left ventricular assist devices (LVAD) has increased at a rapid pace. In the United States, approximately 2400 LVAD are implanted annually 1 and more than 16,000 patients have already received a continuous-flow LVAD. 2 These devices are a life-saving option for advanced heart failure patients who are either not eligible for a heart transplant or too ill to safely wait for a transplant on medical therapy alone. LVAD constitute the following components: (1) an inflow cannula surgically implanted into the left ventricular apex that extracts the blood from the left ventricle (LV) into the pump; (2) a pump enclosure with an impeller that circulates blood; (3) an outflow graft that pulses back the blood from the pump into the ascending aorta; and (4) a surgically tunneled driveline that connects the pump to an external controller that operates and monitors the pump function. The external controller is connected by two power cables to a battery powered source or a power module. Survival rates of patients are continuously improving after implantation of LVAD, but the number of adverse events remains quite high. Approximately 80% of patients will have experienced a major adverse event in the first 2 years after LVAD implantation. The most frequent complications of LVAD are bleeding, infection, and arrhythmia. 3 LVAD infection starts usually at the entry point of the percutaneous driveline and extends from there progressively to the LVAD pump. In case of driveline infection, a new driveline can be implanted in another site and connected to the pump. In case of pump infection, replacing the LVAD pump is challenging because of the development of tight adhesions between the system and the heart. The only remaining option is to try to control the progression of pump infection with long-term systemic antibiotherapy and consider urgent cardiac transplant in eligible patients. The precise evaluation of the extent of infection in the LVAD system is, therefore, key to guide the clinical management of these patients. NUCLEAR IMAGING FOR THE DETECTION OF LVAD INFECTIONWhite blood cell (WBC) SPECT and FDG-PET have both demonstrated their values for the detection of infection in cardiac implantable electronic devices and prosthesis 4 and might thus prove useful for the evaluation of LVAD. On the one hand, WBC SPECT was the first to be evaluated in this indication in a small study including eight patients with a suspicion of LVAD infection. 5 The accumulation of radiolabeled WBC was found highly specific for LVAD infection in this small cohort of patients and allowed for the identification of the extent of infection along the device. The logistics for WBC SPECT imaging are, however, quite demanding for Nuclear Medicine departments with the need to handle blood and radiolabeled cells in a hot lab under sterile conditions, and for patients who undergo two

Procedural recommendations of cardiac PET/CT imaging: standardization in inflammatory-, infective-, infiltrative-, and innervation (4Is)-related cardiovascular diseases: a joint collaboration of the EACVI and the EANM

“…Suspected infection of LVAD -Evaluation of the extent of infection of LVAD -Positive blood culture in a patient with LVAD Image analysis and interpretation LVADs are generally subdivided into 5 regions that have to be assessed separately: driveline exit site, driveline within the subcutaneous tissues, LVAD pump, LVAD inflow cannula, and LVAD outflow cannula.& The presence, intensity and location of the [ 18 F]FDG signal across the different components of the device and the persistency of the signal on NAC images should be described(71). & The analysis of the FDG signal in the pump and cannula is more complex because of the artifacts caused by the device.…”