Atypical Form of the Fourth Criterion for Transient Entrainment

The typical fourth criterion for transient entrainment is defined when both a sudden shortening in conduction interval to and a distinct change in electrogram morphology at a bipolar recording site are demonstrated while performing overdrive pacing of a reentrant tachycardia from a single pacing site at two different constant rates. The purpose of this article was to test the hypothesis that if an intracardiac recording site showing both orthodromic and antidromic capture with entrainment pacing is located suitably distant from the circuit, sudden shortening in conduction interval to that site may occur without any significant change in the bipolar electrogram morphology (i.e., atypical form of the fourth criterion). Atrial overdrive pacing of orthodromic tachycardia was performed in 20 patients with either left anterior (12 patients) or left posterior (8 patients) accessory pathways. We investigated the effects of overdrive pacing from the proximal or distal coronary sinus, specifically effects on the electrogram interval and the electrogram morphology at the right atrial appendage. Overdrive pacing of orthodromic tachycardia from the proximal coronary sinus was performed in 10 of the 12 patients with left anterior accessory pathways; those 10 patients demonstrated the first entrainment criterion at the right atrial appendage site. Overdrive pacing of orthodromic tachycardia at still shorter cycle lengths demonstrated a sudden shortening in conduction interval to the right atrial appendage site. Despite shortening in conduction interval the morphology of the right atrial appendage electrogram was completely or almost identical to that during orthodromic tachycardia, indicating an atypical form of the fourth criterion. This criterion was not demonstrated in patients with left posterior accessory pathways. Thus, atypical fourth entrainment criterion was demonstrated during overdrive pacing of orthodromic tachycardia from the proximal coronary sinus only in patients with left anterior accessory path ways. Demonstration of atypical fourth criterion seems largely dependent on the location of the accessory pathway, the pacing, and the recording sites.     

Quality of ulcer healing influences the relapse of gastric ulcers in humans

The usefulness of dye-contrast endoscopy for the evaluation of the quality of gastric ulcer healing and the prediction of relapse was investigated. Sixty consenting patients whose ulcers healed during 3 months of treatment underwent endoscopy for the identification of the pattern of mucosal regeneration. Patients were monitored for relapses for up to 18 months after antiulcer therapy had ended. The pattern of regeneration was flat in 24 patients, nodular in 25 and intermediate in 11. Internal hypoechoic areas seen by endoscopic ultrasonography were less common and histological maturity was better in the patient group with the flat pattern compared with the patient group with the nodular pattern of mucosal regeneration. Prostaglandin E, synthesis was highest in the group with the flat pattern of mucosal regeneration and the relapse rate was lowest in this group. We conclude that the evaluation of the quality of ulcer healing is possible and that findings in individuals may aid the prediction of relapse for particular patients.     

Demonstration of Right and Left Atrial Dissociation by Atrial Rapid Pacing or Extrastimulation During Fast-Slow (Uncommon) Form of Atrioventricular Nodal Reentrant Tachycardia

Some recent works suggest that extranodal atrial fibers may form part of the reenlry circuit in the atrioventricular (AV) nodal reentrant tachycardia (AVNRT). This hypothesis is based on the fact that the perinodal dissection successfully abolished AVNRT while preserving intact AV conduction. Apart from the surgical success, the electrophysiological evidence supporting this hypothesis has not been demonstrated, especially in the uncommon (fast-slow) form of AVNRT. We present some electrophysiological evidence suggesting atrial participation in eight patients with the fast-slow form of AVNRT. During the tachycardia, rapid pacing or extrastimulation was done from the orifice of the coronary sinus (CS) and the right atrium (RA), while recording the electrograms of the CS and the low septal RA. In seven patients, right and left atrial dissociation was demonstrated during pacing from the RA, while in the remaining one this was demonstrated from the CS. The interatrial dissociation will be unlikely if the intranodal reentry circuit connects with the atria via a single upper common pathway. This suggests that the upper turnaround of the reentry circuit involves atrial tissue and that the extranodal accessory pathway with long conduction times may form the ascending limb of the circuit (atrionodal reentry). Alternatively, the reentry circuit is entirely intranodal and two or more connecting pathways are present between the atria and the circuit.     

Catecholaminergic Polymorphic Ventricular Tachycardia with QT Prolongation

The QT interval in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) is typically normal. However, CPVT patients are sometimes misdiagnosed as concealed long QT syndrome (LQTS), because patients with LQTS also manifest with syncope or sudden death following periods of exertion or extreme emotion. We report a CPVT patient with a pathogenic RyR2 mutation associated with a marked QT prolongation, which normalized after flecainide therapy.     

New Diagnostic Finding to Assess Para-Hisian Pacing Observed in a Patient with a Permanent Form of Junctional Reciprocating Tachycardia

Morphologic Change During Para-Hisian Pacing. Para-Hisian pacing, a useful method to differentiate conduction over an accessory pathway from conduction over the AV node, is assessed essentially by comparing the timing of local atrial electrograms between Hisbundle captured heats and His-bundle noncaptured heats. We describe the case of a patient with a permanent form of junctional reciprocating tachycardia, in whom an atrial double potential was recorded only during the tachycardia at the right posterior septum. During para-Hisian pacing, a morphologic change in the atrial electrogram at the posterior septum was also identified, as well as a change in the retrograde atrial sequence. Since the morphologic change of atrial electrograms during para-Hisian pacing cannot be demonstrated in a patient without an accessory pathway, this new finding could he considered a new additional diagnostic criterion suggesting the presence of an accessory pathway.     

Ocular Membrane Permeability of Hydrophilic Drugs for Ocular Peptide Delivery

The purpose of this study is to investigate the ocular membrane permeability and the permeation mechanism of hydrophilic drugs such as thyrotropin-releasing hormone (TRH), p-nitrophenyl β-cellopentaoside (PNP) and luteinizing hormone-releasing hormone (LHRH). The penetration of hydrophilic drugs was measured across the isolated corneal and conjunctival membranes of albino rabbits using a two-chamber diffusion glass cell. The corneal permeabilities of hydrophilic drugs were much lower than those of beta blockers reported previously. The corneal penetration of TRH was the highest among the hydrophilic drugs studied. Scraping the corneal epithelium increased the penetration of hydrophilic drugs. Conjunctival membranes showed higher permeability to hydrophilic drugs compared with corneal membranes. The permeability of drugs was also analysed by Fick's equation. The partition parameter and diffusion parameter of TRH, PNP and LHRH in the cornea were lower than those in scraped cornea and conjunctiva. In addition to the data of fluorescein isothiocyanate-dextran reported previously, the permeability coefficient of hydrophilic drugs through the cornea, scraped cornea and conjunctiva correlated with molecular weight of the drugs. The diffusion parameters of hydrophilic drugs decreased with an increase of molecular weight for all ocular membranes. The extent of dependency of partition parameters on the molecular weights of drugs varied according to the ocular membrane. These results indicate that ocular membranes are sufficiently different in permeation character and mechanism to control the extent and pathway for ocular absorption of hydrophilic drugs.     

Deficiency of endogenous prostanoids in gastric and duodenal ulcer diseases

The levels of prostaglandin E₂ (PGE₂), 6-keto-prostaglandin F₁α (PGF₁α) and thromboxane B₂ (TXB₂) in endoscopic biopsy specimens from the gastric and duodenal mucosa of healthy volunteers and ulcer patients were measured by radio-immunoassay. The PGE₂ and PGF₁α levels in the mucosa of the corpus of the stomach were lower and the TXB₂ level was higher in 10 patients with gastric ulcer in the corpus than in the 16 healthy subjects. The PGE₂ level in the antral mucosa of 14 patients with gastric ulcer in the antrum was lower than in the controls. In 18 patients with duodenal ulcer, PGE₂ deficiency was more widespread in the entire gastric and duodenal mucosa while the reduced PGF₁α level was limited in the gastric corpus. Lower levels of PGE₂ in patients with antral or duodenal ulcer and of PGE₂ and PGF₁α in patients with corpus ulcer in the anatomical mucosal area including the ulcer site may predispose the mucosa to ulceration.