Quantitative aspects of the metabolic response to pancreatic islet transplantation in rats with severe ketotic diabetes.

Injection of 100-140 mg/Kg of streptozotocin produced severe, ketotic diabetes in 12 pairs of adult rats. Transplantation of intact islets of Langerhans from syngeneic adult donors into a muscle pocket or a pouch created from pancreatic tissue of one animal from each pair eliminated ketonemia in the immediate postoperative period, while ketonemia persisted in the sham-operated controls. Mean survival of transplanted animals was 145 days, versus 70 days for controls. Mean body weight increased and blood sugar decreased in transplanted animals compared with controls; the differences were greatest in those animals which received the largest number of islets per unit body weight. In one animal, all metabolic indices returned to normal for a period of 8 wk following transplantation of 650 islets. After gaining to 300% of initial body weight, diabetes reappeared in this transplanted animal and was again reversed by a second transplantation. The metabolic data indicate that: (1) islet tissue from adult donors survives and functions in severely diabetic, ketotic hosts; and (2) metabolic response to transplantation is a function of the ratio of islet tissue to body mass, a minimum ratio of about 2-3 islets/gm body weight being required to maintain normal homeostasis.     

Epicardial atrial pacing

A modification of the technique for placing a permanent epicardial electrode to the atrium is described. It results in long-term atrial pacing and low sensing thresholds. The method requires meticulous surgical technique but is reliable, safe, and free from serious or long-term complications.     

Pacemaker wire extension for permanent and temporary pacing

A pacemaker wire extension was designed and used for temporary pacing in the postoperative period following open-heart operations. When permanent pacing became indicated, the exteriorized extension was removed and the pacemaker was connected to the permanent electrode and placed subcutaneously. This extension wire eliminated repeat thoracotomy following tricuspid valve replacement and enabled us to implant one reliable set of wires to the myocardium. The extension is easily removed using firm traction (Cordis) or local anesthesia (Medtronic).     

Pericardial Decompression

Pericardial tamponade and chronic pericardial effusion were treated in 32 patients by creating a subxiphoid pericardial window under local anesthesia in preference to pericardiocentesis or pericardiectomy. Chest roentgenograms, fluoroscopy, and cardiac catheterization as standard clinical methods of diagnosis have been largely replaced by echocardiography as the most sensitive method for detecting pericardial effusion. Eleven patients had pericarditis of viral, uremic, or purulent origin. Two had intrapericardial hemorrhage following catheter perforation of the heart. Four had pericardial effusion associated with cardiomyopathy and rheumatoid arthritis. In the remaining 15 patients malignancy was the cause of tamponade. In 10 patients we attempted to control the effusion initially with pericardiocentesis. Five of these (50%) required an additional procedure. In 22 patients subxiphoid pericardial decompression was the primary method of treatment; there were no fatalities during or immediately following operation. None of these patients has had any recurrence of tamponade or effusion for up to three years.     

A permanent experimental model for reversible myocardial anoxia

A new permanent preparation for studying myocardial response to reversible ischemia was defined and characterized in 46 dogs. The left mammary artery was anastomosed to the second diagonal branch of the left anterior descending coronary artery. The artery distal to the anastomosis served as the sole vascular supply for a myocardial pedicle created by a simultaneous incision and suture technique. The venous drainage was left intact, draining blood to the great cardiac vein and coronary sinus.The pedicles so constructed were an anatomically defined myocardial segment with an independent yet controllable vascular supply that maintained viable, functioning tissue. Functional continuity with surrounding myocardium was preserved. There was no damage to adjacent tissue. Overall ventricular function was maintained, and permanent preparations were readily available for study. Occlusion of the mammary artery for a 15-minute period produced structural and functional changes that were completely reversible with 30 minutes of revascularization. Sixty minutes of occlusion produced severe morphological and functional damage that was only slightly reversible. Additional applications of the model are discussed.     

Decompression of the heart with siphon drainage

A simple technique for inducing intracavitary hypothermic cardioplegia and decompressing the left heart through the ascending aorta is presented. The technique is based on siphon drainage, which eliminates the dangers of air embolism.