William H. Fleming

HETEROGENEITY OF HEMATOPOIETIC STEM CELLS

Hematopoietic stem cells are capable of multi-lineage differentiation to all blood cell types as well as self-renewal and radioprotection. Thy-1.1lo Lin-/lo Sca-1+ cells are a heterogeneous mixture of quiescent and self-renewing hematopoietic stem cells as well as multi-lineage expanding cells.

Fourteen Years of Implanted Pacemakers in Children

Twenty-six children who had permanent pacemakers implanted at 6 hours to 11 years of age have been followed for up to 163 months. There were 14 children with surgical heart block, 9 with congenital heart block, 2 with postcatheterization complete heart block, and 1 with bradytachydysrhythmia syndrome. Eighteen of the 26 patients (69%) are still being paced with their original electrodes, some for more than eight years. Sixty pulse generators lasted an average of 17 months (range, 1 to 55 months). Five of the 26 patients (19%) are dead. Three died of noncorrectable heart disease, but there were 2 sudden unexplained deaths at home, both apparently due to sudden arrhtthmias. Both of these patients had received fixed-rate pulse generators, and 1 had a known potential for competing rhythms. The current optimal choices of equipment and techniques, including the role of synchronized, demand, lithium-powered, and nuclear-powered pulse generators, are discussed.

Initial Experience with a Sutureless, Screw-in Electrode for Cardiac Pacing

Abstract This report is based on our initial experience with a new sutureless, corkscrew electrode for cardiac pacing. The electrode may be inserted quickly and securely under direct vision through a small anterior mediastinal or transxiphoid incision. This technique, which was employed in 26 patients between July, 1971, and December, 1972, was developed in an attempt to gain the advantages of both the pervenous and epicardial approaches, i.e., secure placement of the electrode in the myocardium with a minor, well-tolerated procedure that can be performed under local anesthesia. Results to date are very promising and indicate that the technique may very well become the method of choice in the future.

Balanced Drainage of the Contaminated Pneumonectomy Space

The patient who needs a pneumonectomy but has an infected pleural cavity faces the probability of an empyema of the pneumonectomy space. Balanced drainage of a contaminated space may avoid this very serious complication. A patient with obstructing bronchogenic carcinoma associated with distal parenchymal suppuration and empyema is discussed. A pneumonectomy with balanced drainage of the pleural space was performed. After three weeks the mediastinum was stable, and daily irrigation of the space with antibiotic solution was begun. Following foourteen days of irrigation, the cavity was filled with antibiotic solution and closed. Follow-up has shown no subsequent space problems or infection. Balanced drainage is a useful method of dealing with a contaminated pneumonectomy space.