Detection of early renal transplant rejection by minimally-invasive monitoring of impedance variability.

BACKGROUND: Allograft rejection that occurs after renal transplants is identified by surveillance biopsies or by abnormal laboratory and/or hemodynamic data. The latter are insensitive markers of rejection that may not appear until significant histologic damage has already occurred. Therefore, a sensitive and specific non-invasive method of detecting early rejection of transplanted solid organs is needed. METHOD: A single canine renal allograft was implanted followed by bilateral nephrectomy. Bipolar pacing electrodes were implanted at each end of the transplanted kidney. A second set of electrodes was implanted in the liver, which served as a non-rejecting normal organ. Electrodes were connected to an implantable sensor placed in the subcutaneous tissue. Electrical tissue impedance levels were telemetrically downloaded daily. The clinical status of the transplanted organ was monitored by following the blood urea nitrogen and serum creatinine levels, urine output, and clinical appearance. After tissue impedance levels had stabilized, all immunosuppressants were abruptly discontinued. Clinical signs of rejection were then observed after a few days. RESULTS: Rejection was accompanied by changes in electrical impedance of the implanted organ. These changes, when observed, occurred 1-5 days before clinical signs of rejection appeared. CONCLUSION: Analyses of these data suggest that development of a minimally-invasive high-confidence sensor of early rejection of solid organ transplants is feasible.

One stage side-to-side replacement of infected pulse generators and leads.

Infected and contaminated cardiac pulse generators and leads must be removed entirely in order to effect a cure. We have shown through our experience with 68 consecutive cases that explantation of the offending system and replacement of a new device on the opposite side can be safely accomplished in one sitting--a side-to-side replacement--as long as there is appropriate case selection. There were no early or late infections of the new operative site.

Thirty-one years of clinical experience with "nuclear-powered" pacemakers.

From 1973 through 1987, 164 radioisotope powered ("nuclear") pacemakers were implanted in 139 patients at the Newark Beth Israel Medical Center. Patient survival was much as might be expected from an age group as selected for this program. At 31 years (January 2005), 12 of the 139 patients (9%) were still alive. The experience reported here encompassed a span of 16 years of implantation with a follow-up of slightly more than 31 years. The problems encountered along the way were not remarkably different from those encountered in general clinical experience with pacemakers, except that the number of reoperations was fewer. In fact, most patients died with the initial implant in place. Deaths most commonly were due to cardiac causes (54%). The frequency of malignancies was similar to that of the age-matched population; primary tumor sites were randomly distributed. These results show that nuclear pacemakers were safe and reliable. Their longevity and the resulting decrease in reoperations offset their greater initial cost.

Results of coronary artery endarterectomy and coronary artery bypass grafting for diffuse coronary artery disease.

BACKGROUND: Coronary artery endarterectomy with coronary artery bypass grafting for diffuse coronary artery disease has been associated with increased morbidity and mortality. We evaluated our institutional experience to redefine the role of coronary endarterectomy for diffuse coronary artery disease. METHODS: From 1985 to 2002 isolated coronary artery endarterectomy with coronary artery bypass grafting was performed in 1,478 consecutive patients. The short-term outcomes were compared with concurrent series of conventional coronary artery bypass graft surgery, and risk factors for adverse outcomes after coronary endarterectomy were identified. RESULTS: Patients in the coronary endarterectomy group were of higher risk with increased incidence of comorbidities and three-vessel coronary disease. The operative mortality (3.2% versus control 2.2%; p = 0.03) and the incidence of major postoperative morbidity (not significant) were comparable between the groups. Prolonged cardiopulmonary bypass time, recent acute myocardial infarction, redo surgery, and poor ventricular function were important predictors of in-hospital mortality. Vessel endarterectomized, technique of endarterectomy, and cardiopulmonary bypass versus off-pump technique did not alter results. At long-term follow-up, 5-year and 10-year survivals were 83% +/- 5%, and 74% +/- 3%, respectively, and freedom from angina at 5 and 10 years was 75% +/- 5%, and 69% +/- 4%, respectively, with 96% of survivors in New York Heart Association class II. CONCLUSIONS: In selected patients with diffuse coronary artery disease, coronary endarterectomy can be used as a tool for myocardial revascularization. The operative mortality and major morbidity were comparable or similar to coronary artery bypass grafting, and short-term and long-term results were favorable.

Endovascular delivery of vein segments with valves versus direct anastomosis.

PURPOSE: To demonstrate an experimental model designed to allow placement of a vein segment containing a valve into a femoral vein without the need for anastomoses or surgical incision on the target limbs. METHODS: Segments of jugular veins containing valves were harvested bilaterally from 7 female dogs weighing 30 to 40 kg. One of the vein segments was then interposed into one femoral vein, using a standard surgical end-to-end anastomosis. Another segment was loaded into a self-expanding nitinol stent, everted, and secured outside of the stent. This vein-coated stent was then deployed from the jugular approach into the opposite common femoral vein. The endpoint of the study was thrombosis of one of the veins segments or patency at 120 days. The function of the valves was tested prior to completion of the study by instilling dye under incremental pressures and recording the pressure necessary to cause reflux. Light microscopy and electron microscopy were utilized to evaluate structure of the valves at study endpoint. RESULTS: Both grafts in one dog occluded during the second week after surgery. Anastomotic and vein-stented sites remained patent in the remaining 6 animals for 120 days. Retrograde phlebography demonstrated valve competency bilaterally in all cases. The reflux pressures on the stented side averaged 70 mmHg while the transplanted vein segment averaged 55 mmHg. Light microscopy and electron microscopy showed intact vein valve structure in all segments at the completion of the study. CONCLUSIONS: This experimental work demonstrates that endovascular delivery of a native canine vein containing a competent valve is feasible and effective.

An alternate site for pacemaker placement when standard locations are not available.

In patients with no standard sites available for venous access and pulse generator location, the authors found that tunneling the leads from the jugular vein under the clavicle and placing this pulse generator beneath the latissimus dorsi muscle was a satisfactory alternative.

The nature and frequency of postimplant surgical interventions: a realistic appraisal.

The purpose of this retrospective study was to investigate the nature and frequency of surgical reinterventions after primary pacemaker implantation in patients who survived at least 20-30 years. Eighty-five such patients were identified, 32 of whom had radioisotopic (nuclear) implants, and 53 lithium battery powered lithium units. Excluding reoperations within the first 3 months, patients with nuclear implants experienced about two reoperations in 25 years, while those with lithium experienced one every 8 years. The most frequent reasons for surgery were pulse generator replacements, lead revisions, and mode changes, particularly in the nuclear group. There were no premature device failures. This study allows us to make reasonable predictions to patients about the experience a pacemaker implantation, and reassures us about the reliability of the devices that were implanted in the past.