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PubMed1993

[Radiofrequency ablation of accessory pathways in pre-excitation syndrome].

Various parameters relating to the radio-frequency ablation of accessory pathways were studied in 53 patients (27 males, 26 females: mean age 38.5 [14-64] years) with a history of paroxysmal tachycardia (over 1 month to 50 years), shown to be caused by an accessory pathway (Wolff-Parkinson-White syndrome). In all patients the following values were obtained: (1) number of procedures necessary to achieve permanent blockage of the accessory pathway (1-4); (2) duration of each procedure (45-420 min); (3) duration of fluoroscopy (5-102 min); (4) number of necessary radio-frequency applications (1-48); and (5) cumulative energy per procedure. To ablate left-lateral pathways (n = 10) required fewer procedures, shorter duration per procedure, shorter fluoroscopy time, fewer current applications and less total energy than coagulation of right-sided pathways (n = 10). Those various parameters were greatest for ablation of septal and para-septal pathways (n = 9). Pathways which conducted only retrogradely (n = 15) were more difficult to ablate than those with anterograde conduction (n = 38). There were two complications. In one case a tension pneumothorax occurred after faulty puncture of the subclavian vein; in the other, the left ventricle was perforated causing an acute tamponade which required pericardiocentesis with subsequent suture closure of the perforation. It is concluded that, in principle, all accessory pathways, regardless of their conduction potential and site, can be ablated by a radio-frequency current.

Adolescent↗
PubMed1996

Morphologic characteristics of primary nonperforative intestinal blast injuries in rats and their evolution to secondary perforations.

Five hundred and fifty Wistar rats were investigated to determine the frequency of secondary intestinal perforations after exposure to nonperforating blasts and the evolution of the morphological changes from hematoma through to necrosis and gangrene. The animals were observed at different times for a period of 14 days from the moment that the injury was inflicted. Microscopic findings showed that alterations began in the mucosal layer where they were most extensive, then spread to the submucosal layer, muscular layer, and serosal layer, respectively. Examination of the intestinal wall revealed an evolution of the injury from hematoma to necrosis to gangrene, resulting in secondary intestinal perforation. The secondary wounds had centrifugal patterns, opposite those of the original wound pathways. Based on these observations, the mechanism of evolution of primary nonperforating intestinal blast injury into secondary intestinal perforations is presented.

Animals↗
PubMed1996

Homosynaptic and heterosynaptic changes in driving of dentate gyrus interneurons after brief tetanic stimulation in vivo.

This study addressed changes in interneuron driving in the dentate gyrus (DG) of urethane-anaesthetized rats in response to tetanic stimulation of the perforant path (PP) or the converging dentate commissural pathway (CP). Using an extracellular tungsten electrode, we recorded from putative interneurons in the DG that fired to stimulation of both the PP and the CP. Conditioning trains (400 Hz, 17.5 ms) were delivered to each pathway individually and to the two pathways together. The primary measure of synaptic drive was the latency of interneuron discharge. High-intensity PP tetany, CP tetany, and paired tetany consistently reduced firing latency to CP driving (P < .05 for all three), indicating an LTP-like increase in synaptic activation through the CP. High-intensity PP tetany decreased latency to PP driving in only two of seven cases. Heterosynaptic changes occurred frequently in individual experiments. Activity-mediated adjustments in synaptic driving of inhibitory interneurons could play a role in normal physiological function.

Animals↗
PubMed1983

Theta rhythm related hippocampal cell discharges in the urethane anaesthetized rat: evidence for a predominant entorhinal input.

Unit spike activity and slow wave field potentials were recorded in the CA1 pyramidal layer and the dentate granular layer of the dorsal hippocampus of urethane anaesthetized rats during theta rhythm. 70% of the units in the pyramidal layer and all units in the granular layer, having a discharge pattern related to theta rhythm, had their mean moment of discharge in the positive phase of the theta wave recorded in the pyramidal layer. Combined with the results of a modelling study (Holsheimer et al. 1982) it appears that in rat under urethane the theta modulated input to the CA1 pyramidal cells and the dentate granular cells will be mediated predominantly by pathways which terminate distally at these cells: the perforant path.

Action Potentials↗
PubMed1996

[Intravascular stents for treatment of systemic venous obstructions].

Two young adults, 16 and 18 years of age were admitted with complete occlusion of the superior vena cava pathway following previous Mustard procedure. In both patients, perforation of complete occluded vein segment using a straight guidewire and subsequent sequential enlargement by balloon dilation were successfully performed by a left subclavian vein approach. Implantation of a 30 mm Palmaz-stent resulted in a widely patent channel of the vena cava superior into the systemic venous atrium. In short-term follow-up of 3 months both stents remained patent. Repeat dilation of the stents was performed after 3 months. A third patient with systemic venous obstruction was a 3-year old child who suffered low cardiac output following modified Fontan operation caused by a narrowing of the superior vena cava to right pulmonary artery connection and stenosis of distal left pulmonary artery. The severe hemodynamic problem was resolved by implantation of Palmaz-stents in the two separate obstructions. At recatheterization 6 months later, both stents were patent without any residual pressure gradient.

Adolescent↗
PubMed2003

Impact of a clinical pathway and standardization of treatment for acute appendicitis.

PURPOSE: Acute appendicitis is one of the most common surgical diseases. Simple and precise guidelines for treating acute appendicitis are necessary for improving the treatment outcome of this disease. The purpose of this study was to determine the impact of a clinical pathway and standardization of treatment for acute appendicitis at our hospital. METHODS: The clinical pathway and standardization of treatment for acute appendicitis were introduced to our hospital in January 2000. We compared the length of hospitalization, postoperative stay, hospital costs, and operation time during the years before and the years after their introduction. RESULTS: There was no significant difference in the clinical characteristics of the 73 patients in the control group and the 112 patients in the pathway group. There were 6 (8.2%) and 24 (21.4%) cases of perforated appendicitis in the respective groups. The mean length of hospitalization ( P < 0.001), postoperative stay ( P < 0.001), and hospital costs ( P < 0.01) were significantly less in the patients in the pathway group who underwent surgery. CONCLUSION: Our clinical pathway and standardization of treatment for acute appendicitis proved effective for treating patients with acute appendicitis and minimizing costs without compromising patient care.

Acute Disease↗
PubMed1981

Glutamate in hippocampal pathways.

The three consecutive main excitatory neurone projections in the hippocampal formation (the perforant path, the mossy fibres and the pyramidal cell axons) all show acidic amino acid uptake in their terminals. This is in accordance with other data pointing to the transmitter function of glutamate and/or aspartate in the perforant path and pyramidal cell axons. In the mossy fibres the role of these amino acids has so far not been determined. The localization of glutamate and aspartate uptake in the excitatory axon systems contrasts with the localization of GABA uptake in the axons of the inhibitory basket cells and other short axon neurones.

Animals↗
PubMed1993

Entorhinal-hippocampal connections: a speculative view of their function.

On the basis of neuroanatomical studies, the entorhinal cortex (EC) has long been regarded as a relay station that provides the major source of afferent input to the hippocampus. The perforant path input to the dentate gyrus from layer II has traditionally been regarded as the major pathway by which information is transferred. However, electrophysiological studies are now indicating that other elements of the perforant path that project directly to CA1 and CA3 are more important than thought previously, and that the properties of different neuronal elements in the EC may determine the way in which information is passed on to and processed by the hippocampus. This article summarizes some of the properties of synaptic transmission in the EC and speculates on how frequency-dependent changes in transmission may be involved in the pre- and post-processing of hippocampal information by the EC.

Action Potentials↗
PubMed1990

[Simultaneous operation of WPW syndrome combined with mitral regurgitation caused by infective endocarditis].

A case of WPW syndrome combined with mitral regurgitation caused by infective endocarditis underwent surgical division of accessory pathway and mitral valve replacement preserving posterior leaflet simultaneously. A 56-years old woman suffered atrial fibrillation with pseudo VT and cardiac failure caused by mitral regurgitation. Electro-physiological study (EPS) revealed accessory pathway in postero-lateral wall in left atrium and atrio-fascicular pathway like James bundle in AV node. ECHO cardiography showed mitral valve prolapse and severe regurgitation. Accessory pathway was divided surgically and deep freeze coagulation was followed. Perforation of anterior leaflet and chordal rupture of posterior leaflet caused by infective endocarditis were repaired by annuloplasty (Kay and McGoon method) at first, but regurgitation retained moderately. After re-clamping of aorta, mitral valve was replaced with prosthesis (SJM 29 mm) preserving posterior leaflet. Postoperative examination revealed division of accessory pathway and no regurgitation of mitral prosthesis.

Endocarditis, Bacterial↗
PubMed2002

Cryothermic ablation within the coronary sinus of an epicardial posterolateral pathway.

Radiofrequency ablation inside the coronary sinus (CS) is associated with the risk of vein stenosis, or perforation or damage to the circumflex artery. Cryothermic ablation has proved less harmful, but there are no data on its use within a venous structure. A patient with a posterolateral accessory pathway underwent several unsuccessful attempts at endocardial ablation. Ablation then was performed with cool energy within the CS, where the shortest VA interval and a possible Kent potential were recorded. Selective left coronary angiography showed a normal circumflex artery and the absence of lesions of the CS. Six months later, the patient was asymptomatic without taking antiarrhythmic drugs. We conclude that cryoablation within the CS may be effective and safe.

Adult↗
PubMed1992

Alternate pathways for chloride conductance activation in normal and cystic fibrosis airway epithelial cells.

Using whole cell patch-clamp and perforated patch recording techniques on human cystic fibrosis (CF) and non-CF airway epithelial cells, we sought to determine whether a single Cl- conductance (GCl) could be modulated via different regulatory pathways or whether multiple conductances could be identified. Cl- current in both CF and non-CF cells was activated by cellular swelling as well as by an elevation in intracellular calcium ([Ca2+]i). While the adenosine 3',5'-cyclic monophosphate (cAMP)-activated GCl was absent in CF cells, its activation in non-CF cells was only observed in the perforated patch configuration at lower temperatures (24 degrees C) or infrequently in the whole cell configuration at elevated temperatures (33 degrees C). Currents activated by all three regulatory pathways were sensitive to the Cl- channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). Further increases in current activation could be produced by cellular swelling after maximal Ca2+ or cAMP-induced current activation. Intracellular application of a peptide inhibitor of Ca(2+)-calmodulin-dependent protein kinase selectively blocked the Ca(2+)-dependent current activation while leaving the swelling-induced current increase intact. These results are consistent with the presence of multiple anion conductances in both CF and non-CF airway cells. The heterogeneity of the responses to the three regulatory stimuli, however, prevented the correlation of a specific anion conductance with a separate modulatory pathway based on characteristic voltage-dependent kinetics and conductance.

Calcium↗
PubMed2006

Computed tomography-based clinical diagnostic pathway for acute appendicitis: prospective validation.

BACKGROUND: Despite our regular use of CT for suspected appendicitis, a recent study at our institution demonstrated a negative appendectomy (NA) rate similar to our rate 15 years earlier. Based on analysis of this data, a diagnostic pathway was implemented prospectively for adult patients with possible appendicitis. STUDY DESIGN: Rates of CT, NA, and perforation for nonpregnant patients over 14 years of age undergoing appendectomy between August 2001 and August 2002 (PRE) were compared with prospectively collected pathway data (PATH, August 2004 to August 2005). All PATH patients were evaluated by a surgeon before CT. All females underwent CT. CT was obtained in male patients with low suspicion or pain for longer than 48 hours. After negative CT, patients were discharged from the emergency department or admitted for observation. RESULTS: There was a substantial decrease in NA rate after implementation of the pathway (4% PATH [8 of 183] versus 16% PRE [31 of 196], p < 0.001), without a change in the rate of perforation (11% PATH [20 of 175] versus 8% PRE [13 of 165], p = 0.28) or frequency of preoperative CT (59% PATH [108 of 183] versus 60% PRE [118 of 196], p = 0.84). CONCLUSIONS: Frequent appendiceal CT alone does not ensure surgical diagnostic accuracy. CT need not be used in all patients to achieve very low NA rates. An evidence-based diagnostic algorithm incorporating early surgical evaluation, objective criteria for preoperative CT, deterrence of early operation after negative CT, and use of CT to facilitate safe discharge led to substantial improvements in the care of our adult population presenting with possible appendicitis.

Acute Disease↗
PubMed2003

Perforated appendicitis in children: is there a best treatment?

PURPOSE: This study was performed to provide outcome data for the development of evidenced-based management techniques for children with appendicitis in the authors' hospital. METHODS: This is a retrospective analysis of 1,196 consecutive children with appendicitis over a 5-year period (1996 to 2001) at a metropolitan hospital. RESULTS: The median age was 9 years (7 months to 18 years). The perforation rate was 38.9%, and the nonappendicitis rate was 5.6%. Predictors of perforation included age less than 8 years, Hispanic ethnicity, generalized abdominal tenderness, rebound tenderness, and increased number of bands. In perforated cases, the median length of stay was 5 days, and the complication rate was 13.5%. There was no difference in complication rates related to type or timing of antibiotics or related to the individual surgeon. There was no difference in infection rates related to type of wound management. CONCLUSIONS: Children with perforated appendicitis are treated effectively by a less expensive broad-spectrum antibiotic regimen, expeditious operation by open or laparoscopic technique, primary wound closure, and postoperative intravenous antibiotics until they are afebrile for 24 hours and have a white blood cell count of less than 12,000/mm3. This approach is to be used in our prospective, randomized analysis of children treated on or off a clinical pathway.

Adolescent↗
PubMed1992

Silent rectal perforation after endoscopic polypectomy: CT features.

A case of silent extraperitoneal rectal perforation secondary to colonoscopic polypectomy is presented. Computed tomography (CT) demonstrated pathways of gas diffusion from the perirectal site to different compartments of the retroperitoneum, to the mediastinum and peritoneum.

Aged↗
PubMed1996

Differential sprouting responses in axonal fiber systems in the dentate gyrus following lesions of the perforant path in WLDs mutant mice.

Axons in both peripheral nerves and central fiber pathways undergo very slow Wallerian degeneration in Wlds mutant mice. It has recently been shown that in Wlds mutant mice there is a delay in the intensification of acetylcholinesterase histochemical staining in the molecular layer of the dentate gyrus following lesions of the entorhinal cortex. Thus, it appears that delayed post-lesion reactive sprouting is associated with the delayed degeneration of cut central axons in this mutant. We have studied the time course of changes in the septohippocampal and the hippocampal commissural projections following interruption of perforant path in Wlds mutant mice and in normal (C57BL/6J) mice using the anterograde tracer, wheat germ agglutinin conjugated horseradish peroxidase. In normal mice, changes in the distribution of labeled septal and commissural axons indicative of sprouting are seen in the dentate molecular layer as early as 3 days post-lesion. The earliest survival time at which similar changes are found in Wlds mutant mice is seven days post-lesion, when an increase in the density of labeled septal axons begins in the outer molecular layer. The delay in the sprouting of commissural axons in the mutant is even longer. Changes in the distribution of labeled commissural axons in the dentate gyrus of Wlds mutant mice are first seen 12 days post-lesion. These results confirm that post-lesion reactive axonal sprouting can be delayed in the central nervous system of Wlds mutant mice. In addition, our results indicate that the extent of this delay may differ among axonal fiber systems. These findings are consistent with the notion that various central axonal systems may respond differentially to sprouting cues and are reminiscent of differences found in the regenerating response exhibited by sensory and motor axons in the Wlds mutant after peripheral nerve cuts.

Animals↗
PubMed1997

Hippocampal pathology in diffuse Lewy body disease using ubiquitin immunohistochemistry.

Various ubiquitin-positive structures in the hippocampus in diffuse Lewy body disease (n=12) and non-demented aged subjects (n=3) were investigated immunohistochemically. These structures were composed of ubiquitin-positive granular structures (UPG), ubiquitin-positive neuritic structures (UPN), spheroidal structures, neuritic plaques, neurofibrillary tangles (NFT), Lewy bodies (LB) and ubiquitin-positive neurons. UPG, UPN, spheroidal structures and neuritic plaques were distributed with special reference to the hippocampal pathway assumed in this study. This pathway was thought to run along the stratum oriens, mostly perforating the stratum pyramidale at many sites of the subiculum and CA1-3, and to end partly in the CA2-3 and the subiculum of the uncus (UPG or UPN). After perforating the stratum pyramidale and giving off terminal branches (ubiquitin-positive neurons or neuritic plaques with degenerative neurites), it was thought to run along the stratum radiatum and continue along the stratum moleculare of the dentate gyrus, forming synapses with the apical dendrites from the stratum pyramidale and the stratum granulosum (spheroidal structures or neuritic plaques). These findings suggest that many of the ubiquitin-positive structures may be caused by degeneration of terminal or distal axons of this pathway. NFT and LB also had a somewhat orderly distribution with reference to this pathway.

Aged↗
PubMed1992

Septotemporal variation of the supragranular projection of the mossy fiber pathway in the dentate gyrus of normal and kindled rats.

Previous studies have demonstrated regional variation in the anatomical organization and physiological properties of the hippocampus along its septotemporal (dorsoventral) axis. In this study, regional variation of the supragranular projection of the mossy fiber pathway in the dentate gyrus of normal and kindled rats was characterized with a scoring method for assessment of the distribution of mossy fiber synaptic terminals detected by Timm histochemistry. In normal rats, there was a sparse projection of the mossy fiber pathway into the supragranular region near the tips and crest of the dentate gyrus along the entire septotemporal axis, and a prominent projection into the supragranular region at the temporal pole. Kindling of the perforant path, amygdala, and olfactory bulb induced synaptic reorganization of the mossy fiber pathway into the supragranular region along the entire septotemporal axis of the dentate gyrus. There was regional variation of the seizure-induced synaptic reorganization along this axis, and distinct septotemporal patterns were observed as a function of the site of kindling stimulation. Kindling of the perforant path induced mossy fiber synaptic reorganization that was relatively more prominent in the septal pole than in the temporal pole of the dentate gyrus. In contrast, rats that received kindling stimulation of the amygdala had a more uniform distribution of synaptic reorganization along the septotemporal axis. As there is regional variation of the anatomical and physiological properties of the human epileptic hippocampus, these observations could be pertinent to human epilepsy.

Animals↗