Faculty Bibliography

BACKGROUND: Mechanical cardiac assistance has recently emerged as a tenable option in the treatment of end-stage heart failure. In spite of recent technical improvements that have reduced the incidence of life-threatening complications, the reported frequency of infections in these patients has remained high. METHODS: Over a 5-year period, 60 patients underwent insertion of a left ventricular assist device (LVAD) at our institution. Detailed medical records were kept prospectively for all patients, and a variety of endpoints were analyzed, including the incidence, nature, and sequelae of infections before and after LVAD implantation and after transplantation. RESULTS: Twenty-nine of 60 patients (48%) undergoing LVAD insertion subsequently had development of infections. The most frequent sites of infection were blood, LVAD drivelines, and central venous catheters, representing 61% of all infections. At the time of LVAD implantation, 13 of 60 patients (22%) had culture-proven infections. In spite of an increased incidence of subsequent infection (77% vs 40%), there were no differences in rates of mortality (31% vs 26%), LVAD endocarditis, (23% vs 11%) and eventual transplantation (62% vs 57%) between these patients and those without periimplantation infections. Although the overall mortality rate was not influenced by infections during LVAD support (28% vs 26%), the development of LVAD endocarditis was associated with a high mortality rate. Finally, although patients with infections during LVAD support had significantly longer median support times than those who remained infection free (101 vs 49 days, respectively), there was no difference in the rate of successful transplantation (59% vs 58%) or in the rate of infection after transplantation (35% vs 28%). CONCLUSIONS: Infections are common in patients undergoing LVAD support, but they do not adversely affect survival, the rate of successful transplantation, or the incidence of posttransplantation infection. Periimplantation infections may increase the risk of subsequent infections, but they also do not influence survival or transplantability. Patients with development of LVAD endocarditis are at increased risk for morbidity and death and require early and aggressive therapy, potentially including device explantation.

The incidence of clinically significant thromboembolic events is reported to be as high as 25% in patients with left ventricular assist devices (LVAD). Clinically detectable neurologic deficits resulting from thromboembolic events are reported to occur at a frequency of 0.0056% per patient-month with the Thermo Cardiosystems Heartmate 1000 (Woburn, MA) intraperitoneal LVAD (TCI). To date, the occurrence of asymptomatic cerebral microemboli in patients with this device has not been characterized. Transcranial doppler (TCD) monitorings were used for evaluation of the incidence of cerebral microembolism in 14 patients with the TCI LVAD. Studies were performed after LVAD support ranging from 7 to 305 days. Overall, 35 studies were obtained from the left middle cerebral artery for a duration of 30 minutes per study and the number of high intensity transient signals (HITS) were recorded. In one patient with a fatal stroke, an average of 0.86 HITS per study period (0.03/min) was observed. In 13 patients without any symptoms, an average of 0.46 HITS per study (0.016/min) was observed. Overall, no HITS were determined in 74% of the studies. Although the clinical significance or the nature of these microemboli is unknown, the data support that microembolism with the TCI LVAD is a rare event despite absence of anticoagulation. Long-term detailed neurocognitive testing and hematologic assessment is needed to establish the clinical relevance of these microemboli in patients with detected signals.

BACKGROUND: Elevated tumor necrosis factor serum levels have been reported in patients with severe congestive heart failure. This study was designed to characterize the cytokine profile in patients with acute circulatory collapse. METHODS: Blood drawn from 14 consecutive patients within 24 hours before undergoing left ventricular assist device placement and after at least 30 days of mechanical assistance or before transplantation was assayed for levels of interleukin 6, interleukin 8, and tumor necrosis factor-alpha. RESULTS: Interleukin 6 level was elevated in 11 (79%), interleukin 8 in 10 (71%), and tumor necrosis factor in 2 (14%) of the 14 patients. After hemodynamic recovery, interleukin 6 levels decreased from 33.6 +/- 9 pg/mL to 11.3 +/- 4 pg/mL (p = 0.05) and interleukin 8 levels decreased from 122 +/- 34 pg/mL to 19.7 +/- 8 pg/mL (p = 0.005). Tumor necrosis factor-alpha levels did not vary significantly; they were associated with infection in 2 left ventricular assist device recipients and normalized after left ventricular assist device support. All patients had resolution of circulatory shock after mechanical support and had improvement in parameters of end-organ function. CONCLUSIONS: Circulatory shock treated with left ventricular assist device placement is associated with a proinflammatory response similar to that seen in septic shock. The decrease in cytokine serum levels that follows hemodynamic recovery suggests that these cytokines may be markers of tissue damage and may modulate cardiac dysfunction.

BACKGROUND: Lung volume reduction surgery has shown early promise as a palliative therapy in severe emphysema. Selection of potential candidates has been based on certain functional and anatomic criteria, and a variety of operative contraindications have been proposed. METHODS: Over 15 months, we performed lung volume reduction surgery in 85 patients selected on the basis of severe hyperinflation with air trapping, diaphragmatic dysfunction, and disease heterogeneity. Patients were not excluded on the basis of severe hypercapnia, steroid dependence, profound pulmonary dysfunction, or inability to complete preoperative rehabilitation. RESULTS: We observed significant improvements in pulmonary function, exercise capacity, and dyspnea, with an acceptable 30-day perioperative mortality of 7% and actuarial survival of 90% and 83% at 6 and 12 months, respectively. In each "high-risk" group, perioperative mortality, actuarial survival to 1 year, and functional results were equivalent, and in some cases superior, to those in the corresponding "low-risk" patients. CONCLUSIONS: Severe hypercapnia, steroid dependence, profound pulmonary dysfunction, and inability to complete preoperative rehabilitation do not preclude successful lung volume reduction surgery and should not be regarded as absolute exclusionary criteria.