Prolonged Asymptomatic Torsade de Pointes

Torsade de pointer is often associated with syncope, particularly when prolonged. We report a cane of prolonged asymptomatic torsade de pointes in a 68-year-old woman being treated with quinidine gluconate for paroxysmal atrial fibrillation. Ambulatory monitoring obtained one week after an increase in the daily qninidine dosage demonstrated one minute of polymorphous ventricular tachycardia. The patient remained entirely asymptomatic throughout the time of the arrhythmia. Therefore, a lack of symptoms in patients at risk for torsade de pointes may not exclude the presence of this arrhythmia.     

Secreted antigens of filarial nematodes: a survey and characterization of in vitro excreted/secreted products of adult Brugia malayi

We report here a broad analysis of the excretory/secretory (E/S) products of adult Brugia malayi, collected by in-vitro cultivation of the parasite. Culture media and conditions were optimized, and non-essential amino acids were found to be crucial for efficient protein synthesis under cell- and serum-free culture conditions. A close correlation was found between total protein secretion, phosphorylcholine-bearing antigen release and lactate production on each day of culture, indicating that E/S molecules are actively secreted. Parasites cultured in vitro take 2-3 days to adjust to the new environment, and show peak levels of secretion at days 3 and 4. The active secretion of phosphorylcholine by the parasite therefore justifies the measurement of this molecule as an indication of active infection, possibly reflecting total worm burdens. By comparing metabolically labelled E/S from male and female worms, several molecules of low mol. wt, namely 10,000, 13,000, 14,000 and 22,000, together with high mol. wt components of above 12,000 were found to be female specific. Tracing the origin of the E/S products, several molecules were also found to be associated with the surface. Among these, there are at least two glycoproteins, 29,000 and 51,000 of which the 29,000 molecule is a major surface protein. The immunogenicity of the E/S was examined and antigenic cross-reactivity was found with sera from most filarial infections but not with non-filarial nematodiases such as hookworm or Trichinella. However, two molecules of low mol. wt, 15,000 and 19,000, were not recognized by anti-Onchocerca sera and appeared to be potential Brugia-specific diagnostic molecules. Possible functional roles of the adult E/S products were examined but we could find no evidence of protease activity in the E/S or glutathione S-transferase activity in either the E/S or in whole somatic extract.     

Relationship Between Serum Potassium Concentration and Risk of Recurrent Ventricular Tachycardia or Ventricular Fibrillation

INTRODUCTION: Electrolyte abnormalities are considered a correctable cause of a life-threatening ventricular arrhythmia according to American Heart Association/American College of Cardiology Practice Guidelines, and ventricular tachycardia or ventricular fibrillation in the setting of an electrolyte abnormality is considered a class III indication for defibrillator implantation. However, there are little data to support this recommendation. The purpose of this study was to determine the risk of a recurrent sustained ventricular arrhythmia in patients with a low serum potassium concentration at the time of an initial episode of a sustained ventricular arrhythmia. METHODS AND RESULTS: One hundred sixty-nine consecutive patients who presented with a sustained ventricular arrhythmia and a serum potassium concentration determined on the day of the arrhythmia underwent defibrillator implantation. All patients had structural heart disease and left ventricular ejection fraction of 0.32+/-0.15. On the day of the index arrhythmia, 30% of the patients had a serum potassium concentration <3.5 or >5.0 mEq/L, including 7% who had a serum potassium concentration <3.0 or >6.0 mEq/L. For the entire cohort of patients, freedom from a recurrent sustained ventricular arrhythmia was 18% at 5 years and was not significantly different among patients with a serum potassium concentration <3.5 mEq/L (23%), between 3.5 and 5.0 mEq/L (16%), and >5.0 mEq/L (5%; P = 0.1). CONCLUSION: The results of the present study suggest that patients with structural heart disease and an abnormal serum potassium concentration at the time of an initial episode of sustained ventricular tachycardia or ventricular fibrillation are at high risk for a recurrent ventricular arrhythmia; therefore, implantable defibrillator therapy may be reasonable.     

A REVIEW OF COMPLEX TRAUMA TO THE ELBOW

This paper presents a review of common complex elbow traumatic disorders. It presents an algorithm to aid in the management of these cases and discusses indications for radial head replacement and dynamic external fixateurs.     

Detection of Atrial Fibrillation During Sinus Tachycardia Induced by Exercise in Patients with Implantable Atrial Defibrillators

Accurate detection of atrial fibrillation (AF) is essential for appropriate operation of an implantable atrial defibrillator (IAD). However, during episodes of sinus tachycardia, distinction between AF and sinus rhythm (SR) using the "quiet interval" and "baseline crossing" analysis in the detection algorithm of the IAD may be difficult. The efficacy of this AF detection algorithm was tested in five patients implanted with an IAD (MFTRIX, Model 3000 or 3020, InControl Inc.) during treadmill exercise testing. The IADs were programmed to Monitor Mode with a wake up cycle of 1 minute for AF detection using the device nominal parameters or modified parameters, and to mark rhythms appropriate for shock delivery. A mean peak heart rate of 137 ± 26 beats/min was reached during maximum exercise, and one patient developed transient AF. Seventy-eight (75 in SR, 3 in AF) and 91 (89 in SR, 2 in AF) runs of AF detection were performed using the nominal and modified parameters, respectively. The IAD detected AF and SR accurately, except for one episode of false-positive AF detection during sinus tachycardia at the nominal settings, but inappropriate shocks were prevented by minimum RR interval criteria that limited discharge at high heart rate. These results indicate that the AF detection algorithm in the IAD may become more vulnerable to false-positive AF detection during sinus tachycardia, which were avoided by reprogramming the Quiet Interval and minimum RR interval criteria for AF detection. Exercise testing appeared useful to program optimal settings of the IAD in preparation for daily activities.     

Clearance, Translocation, and Excretion of Beryllium following Acute Inhalation of Beryllium Oxide by Beagle Dogs

Clearance, Translocation, and Excretion of Beryllium followingAcute Inhalation of Beryllium Oxide by Beagle Dogs. FINCH, G.L., MEWHINNEY, J. A., HOOVER, M. D., EIDSON, A. R, HALEY, P.J., AND BICE, D. E. (1990). Fundam Appl. Toxicol. 15, 231–241.Beagle dogs inhaled radiolabeled beryllium oxide (7BeO) particlesthat were calcined at either 500 or 1000'C, resulting in eitherhigh (mean of 50 ng/kg body wt) or low (mean of 17 ug/kg bodywt) initial lung burdens (ILBs) of both preparations of BeO.Levels of beryllium in whole body, tissue, and excreta weremeasured by external -y-ray counting. Dogs were euthanized inpairs at 8, 32, 64, and 180 days after exposure to determineberyllium distribution in tissues. Beryllium oxide calcinedat 1000'C was retained more tenaciously in the lungs (62% ofthe ILB retained at 180 days after exposure) than BeO calcinedat 500°C (14% of the ILB retained at 180 days after exposure).Most of the beryllium that was cleared from the lungs and notexcreted was translocated to the tracheobronchial lymph nodes,skeleton, liver, and blood. More beryllium was translocatedto the skeleton and liver at 180 days after inhalation of BeOprepared at 500*C than at 1000'C. The predominant mode of excretionat early times after exposure was through the feces, with urinaryexcretion assuming predominance at later times. These data areimportant for interpreting the toxic effects of beryllium inthe exposed dogs. Furthermore, because little is known concerningthe retention and clearance of inhaled beryllium in man, theseresults provide information that may be used to understand thedisposition of beryllium in accidentally exposed humans.     

Preimplant Atrial Defibrillation Testing with a Temporary Catheter in Sheep

Prior to implantation of an atrial defibrillator, its effectiveness should be tested in each patient. A new catheter design for temporary use with electrodes for atrial defibrillation, electrogram sensing, and pacing was tested in this study. Atrial defibrillation thresholds defined using this temporary catheter were compared to the ones defined by catheters intended for chronic use with an implantable atrial defibrillator. Atrial defibrillation threshold was determined in six sheep using both types of catheters. Each animal was subjected to studies on 2 consecutive days. On the first day, shocks were applied between two of the temporary catheters. On the following day, permanent leads were inserted and atrial defibrillation threshold was redetermined. In both cases, defibrillation electrodes were positioned in the same heart location with one electrode in the distal coronary sinus and the second electrode in the right atrium. Atrial defibrillation threshold was obtained using 10 V increments or decrements to determine the lowest shock intensity needed to defibrillate the atria. Threshold was defined as the shock intensity at which 20 shock percent success was at or between 15 % and 85%. Statistical analysis showed no significant difference (P < 0.05) between atrial defibrillation threshold energy (0.53 J vs 0.55 J), voltage (122 V vs 120 V) or current (2.2 A vs 2.6 A) measured with the temporary catheters and the permanent leads, respectively. These data indicate that temporary catheters can be used for efficacy testing prior to implant of an atrial defibrillator, and that they predict atrial defibrillation threshold adequately for chronic leads.