High-Density Circumferential Pulmonary Vein Mapping with a 20-Pole Expandable Circular Mapping Catheter

The differentiation of pulmonary vein (PV) electrograms from atrial far-field signals during PV isolation (PVI) for atrial fibrillation (AF) may be difficult. In addition, owing to highly variable PV ostial sizes, current fixed-diameter circular PV mapping catheters may not yield optimal electrograms. We evaluated an expandable, circular 15–25 mm diameter, 20-pole mapping catheter for PV mapping during sustained AF in 25 patients. After selective PV angiography to define the ostial position and size, the catheter was introduced into each PV and withdrawn to the most stable proximal position, with optimal wall contact ensured by progressive loop expansion. At each PV ostium, electrograms recorded at high resolution (HR) were compared with those recorded at a resolution similar to that of a standard 10-pole Lasso catheter. After PVI performed during ongoing AF, the presence of residual far-field potentials (FFP) under both set-ups was compared. We mapped 97 PV, including 4 pairs with common ostia. In the HR recordings, the PV potentials had greater amplitude (0.5 ± 0.1 vs 0.3 ± 0.1 mV, P = 0.001) and fragmentation, whereas left atrial FFP were minimized. After successful isolation of all PV, FFP were observed in 33% of left superior and 28% of left inferior PV on the HR recordings, compared to 66% and 61%, respectively under normal resolution. Catheter stability and optimal wall contact, in combination with HR electrograms can optimize circumferential PV mapping during AF and improve the discrimination of FFP postablation.     

Relation Between Cycle Length, Volume, and Pressure in Type I Atrial Flutter

Assuming that type I atrial flutter is a macroreentrant circuit, its cycle length should vary with the atrial dimensions. In order to test this hypothesis, flutter cycle length was measured while inducing atrial volume and pressure changes by postural and pharmacological means in seven patients undergoing a therapeutic programmed stimulation for type 1 atrial flutter conversion. Right atrial volume was estimated from B-mode echocardiography data. Basal values were compared with those obtained during inspiration, expiration, Valsalva maneuver, negative tilt (head down), and positive tilt (head up) with 0.8–1.6 mg p.o. nitroglycerin. The right atrial size increased slightly from 17.8 to 18.3 cm² (P = 0.04) during the pressure load induced by negative tilt (+ 3 mmHg), with a corresponding lengthening of the flutter cycle length from 228 to 233 msec (P = 0.02). Similarly, pressure unloading of -2 mmHg by positive tilting and nitrates was accompanied by a decrease in right atrial size to 16.6 cm² (P = 0.04), with a corresponding decrease in cycle length from 228 to 219 msec (P = 0.03). Respiratory maneuver yielded similar results with an inspiratory cycle lengthening, expiratory shortening, and further shortening during Valsalva maneuver. These experiments demonstrate a direct relation between cycle length and atrial volume in human type I atrial flutter. They underline the importance of the right heart preload and atrial size for the electrophysiological characteristics of type I atrial flutter. Beside its fundamental interest, this finding is important for the understanding of the mechanism of maintenance and therapeutic responses of this common arrhythmia.     

Influence of Viral Infections on Body Weight, Survival, and Tumor Prevalence of B6C3F1 (C57BL/6N ? C3H/HeN) Mice in Carcinogenicity Studies

Sendai virus (SV), mouse hepatitis virus (MHV), and pneumoniavirus of mice (PVM) are common viral infections of mice. Influenceof these viral infections on the prevalence of liver tumors,lung tumors, and lymphoma is of concern in chemical carcinogenicitystudies. Body weight, survival, and tumor prevalence of B6C3F1mice with and without viral infections in 33 male and 34 femaleuntreated control groups and 32 male and 32 female low- andhigh-dose groups of 2-year chemical carcinogenicity studieswere evaluated. In male mice, the SV infection was associatedwith significantly (p < 0.05) higher survival of control,low-dose, and high-dose groups, and higher prevalence of livertumors and lymphoma. The increases in tumor prevalence are possiblydue to an increase in the survival of male mice that had SVinfection. However, when interlaboratory variability and time-relatedeffects were taken into account, the number of significant effectswas consistent with the expected false-positive rate inherentto the statistical procedures. The MHV and PVM infections didnot cause consistent changes in body weight, survival, and tumorprevalences in the control and chemical treatment groups ofmale mice. Viral infections did not cause consistent increasesor decreases in body weight, survival, or tumor prevalence inthe control and chemical treatment groups of female B6C3F1 mice.     

Aldicarb Immunotoxicity: Functional Analysis of Cell-Mediated Immunity and Quantitation of Lymphocyte Subpopulations

Aldicarb Immunotoxicity: Functional Analysis of Cell-MediatedImmunity and Quantitation of Lymphocyte Subpopulations. THOMAS,P., RATAJCZAK, H., DEMETRAL, D., HAGEN, K., AND BARON, R. (1990).Fundam. Appl. Toxicol. 15, 221–230. Adult female B6C3F1mice received distilled water only or water containing 1.0,10, or 100 ppb of aldicarb daily for 34 days. The target concentrationof aldicarb present in the 100 ppb dosing solution was analyticallyverified. To further develop an immune profile of this compound,following aldicarb exposure, the ability of splenic naturalkiller cells and specifically sensitized cytotoxic T-lymphocytesto lyse YAC-1 lymphoma and P815 tumor cells, respectively, wasevaluated. To supplement the functional assays, the impact ofaldicarb exposure on the percentages and absolute numbers oftotal T-cells, T-suppressor, T-helper, and B-cells was evaluated.The absence of statistically significant effects on any of theseparameters supports earlier reports that aldicarb does not resultin adverse effects on the immune system of mice.     

Chronic Dietary Toxicity/Oncogenicity Studies on 2,4-Dichlorophenoxyacetic Acid in Rodents

Forms of 2,4-dichlorophenoxyacetic acid (collectively knownas 2,4-D) are herbicides used to control a wide variety of broadleafand woody plants. Doses in the 2-year chronic/oncogenicity ratstudy were 0, 5, 75, and 150 mg/kg/day. The chronic toxicityparalleled subchronic findings, and a NOEL of 5 mg/kg/day wasestablished. A slight increase in astrocytomas observed (inmales only) at 45 mg/kg/day in a previously conducted chronicrat study was not confirmed in the present study at the highdose of 150 mg/kg/day. Doses in the 2-year mouse oncogenicitystudies were 0, 5, 150, and 300 mg/kg/day for females and 0,5, 62.5, and 125 mg/kg/day for males. No oncogenic effect wasnoted in the study. In summary, the findings of these studiesindicate low chronic toxicity of 2,4-D and the lack of oncogenicresponse to 2,4-D following chronic dietary exposure of 2,4-Din the rat and mouse.     

Canine Exocrine Pancreatic Secretory Changes Induced by an Intragastric Ethanol Test Meal

In five dogs with chronic gastric fistulas (Thomas cannula) and a new type of chronic pancreatic fistula which permits collection of pure nonactivated pancreatic juice after ingestion of a test meal, the following series of experiments were performed: In the first series, a test meal (400 gm. canned dog meat) was given with 200 ml. saline simultaneously infused through the gastric cannula. In response to this stimulus, the 20-minute peak pancreatic flow rate and bicarbonate output were respectively 33% and 34%, of the maximal secretion of the pancreatic gland obtained with secretin in six control dogs provided with gastric and the classical Thomas duodenal fistula. The 20-minute peak protein output represented 84% of the maximal secretory capacity attained with dose-response curves to CCK in the same group of control animals.
In the second series either 1.5 or 2.0 gm./kg. ethanol were given instead of saline. Intragastric ethanol induced a dissociation of pancreatic secretion: a significant inhibition of flow rate, of bicarbonate concentration and output and a significant rise of protein concentration; protein output remaining unchanged.
It is postulated that ethanol, acting on the stomach and duodenojejunum, evokes, independently of its gastrin-releasing capacity', an unknown humoral or nervous mechanism that counteracts the ethanol-elicited cholinergic-mediated inhibition of pancreatic protein secretion which has been previously described.     

THE NATURE OF ARTHRITIS PAIN

A modified version of the McGill Pain Questionnaire in visualanalogue format was used to evaluate the sensory, affectiveand evaluative intensities of pain experienced by 40 patientswith rheumatoid arthritis and 20 patients with degenerativearthritis. The affective component of the pain was found tobe more intense than the sensory component in all patients indicatingthe importance of emotional factors in the pain experience.The sensory aspects of the pain were more complex than the affectiveones reflecting the varied sources and combinations of somaticpathology. There were no significant differences found in theoverall pain experience between rheumatoid and degenerativearthritis. No differences were noted in the evaluative categoryof pain. Overall pain intensity increased with disease durationin both rheumatoid and degenerative arthritis. The relationshipof affective and sensory components of the pain experience didnot alter with duration of disease. KEY WORDS: Arthritis, Pain