Nina S. Braunwald

Pacemaker backup-mode reversion and injury during cardiac surgery

Both electrocautery and internal defibrillation are routinely used in cardiac operations. The cases of 5 patients are presented in whom backup-mode reversion or injury of permanently implanted pulse generators occurred during a cardiac procedure. The theoretical explanations for backup-mode reversion and generator or tissue injury are discussed, and recommendations are made for the management of patients with a pacemaker who are to undergo a cardiac operation.

Treatment of Paroxysmal Supraventricular Tachycardia by Electrical Stimulation of the Carotid-Sinus Nerves

SUPRAVENTRICULAR tachycardia may be terminated by manual pressure on the carotid sinuses or by the administration of parasympathomimetic or of pressor agents. Recently developed technics for the tr...

Toxicity in vital fluorescence microscopy: effect of dimethylsulfoxide, Rhodamine-123, and DiI-Low density lipoprotein on fibroblast growth in vitro

SummaryFluorescence microscopy performed on living cells is a valuable technique for elucidating patterns of cell growth in vitro over artificial biomaterials such as vascular grafts, and for in vivo studies such as identification and treatment of atherosclerotic plaques. Two fluorescent dyes of particular value for vital fluorescence studies are Rhodamine-123 and 3,3′-dioctadecylindocarbocyanine-labeled low density lipoprotein (DiI-LDL). We examined the toxicity of these two dyes and of dimethylsulfoxide (DMSO), a solvent used in Rhodamine-123 studies, on the growth of MRC5 human fetal fibroblasts in monolayer culture. Two parameters of cell growth were quantitated: Cell number (a measure of proliferation), and cell area (a measure of cell spreading), based on microscopic images obtained at the start and end of a 48-h growth period after brief exposure (0.5 h) to test solutions. We found that the recommended solvent for solubilization of Rhodamine-123, DMSO, caused cessation of cell proliferation and actual reduction in the area covered by adherent fibroblasts at concentrations of as low as 0.1% (vol:vol). Rhodamine-123 made up from an aqueous stock solution modestly retarded proliferation and spreading, and there was no significant effect of DiI-LDL on these parameters over prolonged periods of exposure (up to 24 h) in culture. These results demonstrate that the most toxic substance for growing fibroblasts was the solvent DMSO. We conclude that both the solvent vehicle and fluorescent dye should be carefully examined for potential toxicity before such dyes are used for vital fluorescence studies of living cells.

Fluoroscopic Technique of Subclavian Venous Puncture for Permanent Pacing: A Safer and Easier Approach

Infraclavicular subclavian puncture may be performed with fluoroscopic observation of the needle trajectory. In 92 patients so implanted between July 1985 and May 1987 uneventful venous access was achieved in 90, one was unsuccessful and one patient had subcutaneous emphysema, a complication rate of 2.2%.

Pacemaker malfunction after nitrous oxide anesthesia

Abstract Entrapment of gas in the pacemaker pocket has been reported. 1,2 Pacemaker malfunction in those studies was a result of loss of anodal contact, and presented with small amplitude, variable amplitude or absent pacing spikes with loss of ventricular capture. We report a patient in whom pacemaker malfunction was caused by the presence of an anesthetic gas within the pacemaker pocket itself.

It will work: The first successful mitral valve replacement☆

In 1959, a prosthetic mitral valve of flexible polyurethane with Teflon chordae tendineae was designed and fabricated. After a series of experiments in dogs carried out at the Clinic of Surgery at the National Heart Institute, on March 11, 1960, this valve was used as a total replacement of the mitral valve of a 44-year-old woman with mitral regurgitation. After an uneventful postoperative course, she was discharged from the hospital and did well thereafter, but died suddenly, presumably of an arrhythmia, 4 months after operation.

Vital fluorescent staining of human endothelial cells, fibroblasts, and monocytes: Assessment of surface morphology

Vital fluorescent staining of human endothelial cells, fibroblasts, and monocytes seeded on a variety of surfaces has been carried out to develop a method for studying cell growth and interactions on viable cells. Using special fluorochrome markers and monoclonal antibodies, it was possible to differentiate different cell types as they grew on polymer surfaces similar to ones that are presently used on artificial heart valves and vascular grafts.