Exit Block in Myxedema, Treated Effectively by Thyroid Hormone Therapy

A case of a 71-year-old female who developed exit block one year after implantation of a pervenous pacemaker is reported. The pacemaker had been implanted for sick sinus syndrome; the exit block was probably due to the development of severe myxedema which caused high pacing threshold. Normal pacing threshold was obtained on the seventh day of adequate thyroid hormone therapy and a follow-up one year later revealed effective control of the myxedema and no abnormalities in the function of the pacemaker system.     

CO2 Laser Catheter Angioplasty in Human Atherosclerotic Xenograft Arteries

Human atherosclerotic xenograft arteries implanted in five mongrel dogs were subjected to in-traluminal angioplasty using CO₂ laser radiation. CO₂ laser energy was delivered through a silver halide fiber, 0.9 mm in diameter and 100 cm long, inserted into a 6 Fr angiographic catheter. Results indicated that the technique is feasible, relatively simple and may have a low potential for perforation. (J Interven Cardiol 1989:2:1)     

Immunopathology of Schistosoma japonicum and S. mansoni infection in B cell depleted mice

To investigate the role of antibody in the pathogenesis of hepatic granulomas around schistosome eggs, mice were depleted of B cells by treatment from birth with anti-IgM serum and were subsequently infected with Schistosoma japonicum or S. mansoni. Anti-IgM treatment did not affect the development or fecundity of the worms or the larvae within the egg shells. Normal circumoval granulomas were present in the livers of B cell depleted mice 7 or 8 weeks after infection clearly indicating that antibody and immune complexes have no necessary role in the formation of granulomas. Hepatic fibrosis was also similar in B cell depleted and untreated mice at these times. Ten weeks after infection the size of S. japonicum egg granulomas in untreated mice had decreased but no change in the size of granulomas had occurred in B cell depleted mice, and hepatic fibrosis was more marked in treated than in untreated mice. Similar changes were noted in S. mansoni infected mice, assayed at 8 and at 12-13.5 weeks after infection. The effects of B cell depletion in the more chronic infections may be related to the absence of antibody but could also be caused by an influence on B cell-dependent suppressor T cells.     

Ventricular Pacing as the Preferable Mode for Long-Term Pacing in Patients with Carotid Sinus Syncope of the Cardioinhibitory Type

This study was designed to determine the efficacy of long-term VVI pacing in patients having the isolated cardioinhibitory type of carotid sinus syncope. The study included 20 patients suffering from repeated syncopal attacks; all were proven by electrophysiological studies to have isolated forms of cardioinhibitory type carotid sinus syncope. Long-term pacing by the VVI mode was carried out in all patients by programming the pacemaker rate well below the patient's sinus rate. The follow-up period after pacemaker implantation, which ranged from 2 to 54 months (average, 20 months), revealed that none of the patients had any recurrence of syncopal attack. Repeated Holter monitoring showed that ten had permanent sinus rhythm without any artificial pacing activity, while in the other ten, pacemaker activity was recorded--predominant in two patients and rare in the other eight. During Holter monitoring, attacks of weakness were reported by four patients; however, they were not related to pacemaker activity. This report indicates the importance of electrophysiological studies in patients suffering from carotid sinus syncope. These studies make possible the diagnosis of the isolated form of cardioinhibitory type syncope for which VVI pacing offers complete relief of symptomatology, thus rendering AV sequential pacing superfluous.