DDI Pacing in the Bradycardia-Tachycardia Syndrome

The bradycardia-tachycardia syndrome is a subgroup within the larger category of sinus node dysfunction. Pacing is often required to treat either the protracted asystolic spells following the spontaneous termination of a paroxysmal supraventricular tachyarrhythmia or to protect the patient from pharmacologically exacerbated bradycardias. While the optimal pacing mode for this subset of patients remains debatable, recent reports have favored the use of atrial ventricular sequential pacing with intact atrial sensing (DDI). This paper reports our experience with a series of 30 consecutive patients in whom the DDI mode was utilized as part of the management of this syndrome. DDI pacing has been demonstrated to be safe, extremely effective, and easy to use in this group of patients.     

Serum IgE levels in giardiasis

Raised levels of serum immunoglobulin E are found in many parasitic diseases. In order to determine the influence of Giardia lamblia on IgE levels of clinically symptomatic patients, a controlled study was performed. There was no difference between the serum IgE values from Brazilian patients with giardiasis and those from normal Brazilian controls, although in both groups there were many individuals with values higher than the normal range reported from the northern hemisphere.     

EFFECTS OF INTRANASAL CALCITONIN ADMINISTRATION ON PITUITARY GH RESPONSE TO hGHRH (1–29)NH2 IN NORMAL ADULT SUBJECTS

Studies in man demonstrated that intramuscular salmon (s) calcitonin (CT) administration blunted pituitary GH response to hypothalamic stimuli such as arginine infusion and insulin-induced hypoglycaemia. However, the mechanisms underlying this inhibiting action of CT are still unclear. The aim of our study was to investigate the effects of intranasal (i.n.) and i.m. sCT administration on GH secretion elicited by direct pituitary stimulation in man with human GH-releasing hormone (GHRH) (1-29)NH2. Seven healthy non-obese volunteers (five men, two women; mean age +/- SDM 25 +/- 2) underwent a bolus intravenous injection of GHRH, 100 micrograms, alone or associated with sCT, administered either i.n., 300 IU, or i.m., 100 IU. Our data demonstrate a significant decrease in GH secretion after GHRH when either i.n. or i.m. sCT is administered. GH peak (mean +/- SDM); GHRH alone 22.9 +/- 2.5 vs GHRH plus i.n. sCT, 8.9 +/- 1.5 micrograms/l, P less than 0.001; or vs GHRH plus i.m. sCT 12.3 +/- 2.5 micrograms/l, P less than 0.001. Area under the curve of GH secretion: GHRH alone 1211 +/- 196 vs GHRH plus i.n. sCT 551 +/- 116 micrograms 120 min/l. P less than 0.001; or vs GHRH plus i.m. sCT 700 +/- 167 micrograms 120 min/l, P less than 0.001. We conclude that sCT is able to inhibit GHRH-stimulated GH secretion in man.     

Evaluation of a Dual Chamber Implantable Cardioverter Defibrillator for the Treatment of Atrial and Ventricular Arrhythmias

BORIANI, G., et al .: Evaluation of a Dual Chamber Implantable Cardioverter Defibrillator for the Treatment of Atrial and Ventricular Arrhythmias. Eighty-nine patients with a documented history of atrial tachyarrhythmias or fibrillation (AF) received a cardioverter defibrillator designed to selectively differentiate and treat atrial and ventricular arrhythmias. Twenty-two patients received a coronary sinus lead and, therefore, could use a separate shock vector for selective treatment of atrial tachyarrhythmias/AF. The device is designed to treat tachyarrhythmias with antitachycardia pacing (ATP) and/or shock therapy using an atrial and/or a ventricular shock vector. Patients underwent induction and shock termination of atrial or dual tachyarrhythmias (AF/VF) to verify proper device function and to measure the arrhythmia detection time with enhancements and preventive algorithms programmed On and Off, respectively. Detection time for 329 VF inductions was   2.41 ± 0.64  seconds   with enhancements On and   2.29 ± 0.47   with enhancements Off (NS). At implant or predischarge, 283 AF and/or AF/VF (121 atrial and 162 atrial/ventricular fibrillation) were induced. Shock conversion efficacy was 89.8% with AF conversion energies ranging from 0.9 to 27 J. Thirteen of the 23 patients had atrial shock conversions using the separate shock vector with an average conversion energy of   1.9 ± 1.4  J   . (range 0.5–5 J). During follow-up the efficacy of ATP on atrial tachyarrhythmias was 59% and the efficacy of delivered shocks on AF was 85%. This new dual chamber cardioverter defibrillator appropriately detected and classified atrial arrhythmias, and shock therapy for AF was highly effective. The detection algorithm differentiated atrial tachyarrhythmia/AF and did not delay VF detection. The separate shock vector converted induced AF with energies ranging from 0.6 to 5 J. (PACE 2003; 26[Pt. II]:461–465)