Amplitude and Direction of Atrial Depolarization Using a Multipolar Floating Catheter: Principles for a Single Lead VDD Pacing

VDD stimulation using a single catheter for atrial sensing and ventricular sensing and pacing has become a reality. In order to compare the quality of the cavitary atrial electrogram (AEG) and to determine the intraatrial P wave direction and conduction time (CT), we compared, in an acute study, three different types of atrial electrode systems using four different leads, in 53 patients in sinus rhythm. The three electrode systems were: (1) one experimental system with quadripolar orthogonal electrodes using the Goldreyer concept; (2) one experimental system with quadripolar whole ring electrodes; (3) two systems with diagonally oriented half-ring electrodes, one experimental quadripolar and one bipolar CCS commercial (Polysafe A-Track lead). For the experimental systems, the four electrodes forming two independent bipolar pairs were situated on the intraatrial floating portion of a single lead and one supplemental electrode was distally positioned in the right ventricular apex. Bipolar AEGs were recorded at the high and at the low levels of the right atrium. For the CCS lead, the single bipolar AEG was recorded at the high level of the right atrium only. The highest AEG amplitude and the highest values for ventricular far-field rejection were provided by both diagonally oriented half-ring electrodes at the high atrial level and by the whole ring electrodes at the low atrial level. For both atrial levels, the orthogonal electrode system provided the smallest AEG amplitudes, the highest ventricular electrogram amplitudes, and therefore, the smallest values for ventricular far-field rejection.(ABSTRACT TRUNCATED AT 250 WORDS)     

The Lower Esophageal Ring and Esophageal Reflux

Although the lower esophageal ring is an important cause of dysphagia in adults, its pathogenesis is unknown. To better define the relationship between the lower esophageal ring and esophageal reflux, we analyzed, retrospectively, the records of 18 hospitalized patients with radiologically demonstrated rings (16 confirmed by endoscopy and/or surgery). In 16 of these patients, evidence of esophageal reflux including at least one of the following was present: overt esophagitis noted at endoscopy or surgery (14 cases), histologic evidence of esophagitis (3 cases), and/or symptoms of pyrosis or free reflux (13 cases). These findings suggest that 1. reflux is frequently associated with lower esophageal rings and may play a role in their pathogenesis; 2. the radiologic finding of a ring should serve as a clue to the possibility of esophageal reflux and 3. long-term control of dysphagia in these patients may depend upon control of the associated reflux as well as mechanical disruption of the ring.     

A Familial Hemorrhagic Diathesis due to an Antithrombin

1) A familial hemorrhagic diathesis has been found to be due to an antithrombin.

2) This antithrombin is not fibrinogen, antithrombin II, III, or IV, and isnot similar in its characteristics to the antithrombins described in secondaryhemorrhagic conditions.

3) The inheritance of this disorder is not sex-linked but is otherwise notclear. The factor may be a dominant, the expression of which is modified byunknown factors.

Submitted on July 6, 1962 Accepted on October 17, 1962     

Occupational Health and Safety in the National Health Service: The Present and The Future

In this paper we review the type and extent of occupationalhealth services provided by the National Health Service forits own and Local Authority employees. We also enquired intothe extent of occupational hygiene services and safety officersin the National Health Service both in the North Western Regionand in the rest of the country. We consider ways of improvingNational Health Service Occupational Health Units includingthe provision of specialist occupational physicians to eachDistrict. Our conclusions are that future services should be consultantled. Based on our calculations for the North Western Region,this need not cost more than the present arrangements. An occupationalhygiene service should be planned to meet the needs of NationalHealth Service employees. Requests for reprints should be addressed to: Dr Malcolm Gatley, Consultant Occupational Physician, North Manchester General Hospital, Crumpsall, Manchester M8 6RB.     

Pharmacokinetics and Absolute Bioavailability of Cyclosporin Following Intravenous and Abomasal Administration to Sheep

Abstract— Cyclosporin A pharmacokinetics were studied following intravenous and abomasal dosing in an open, crossover study in healthy, merino ewes. Five different doses of cyclosporin A were dispersed in milk and administered into the abomasum through a surgically inserted fistula which simulates oral administration. Cyclosporin A was well tolerated. Whole blood concentrations of cyclosporin A were measured by HPLC and mean clearance (0·45 ± 0·05 L h^?1 kg^?1), distribution volume (4·4 ± 2·0 L kg^?1), mean residence time (9·6 ± 4·1 h) and half-life (12·1 ± 3·1 h) were calculated. Negligible cyclosporin A was excreted in urine or bile. Area under the curve increased proportionally with doses up to 26·3 mg kg^?1, but was curvilinear above this dose. Abomasal bioavailability at 6·4 mg kg^?1 was 0·26 ± 0·09, and mean absorption time was 4·7 ± 11·1 h. Considerable pharmacokinetic variability was observed, particularly after abomasal administration. Cyclosporin A pharmacokinetics in sheep lie within the values reported in man after renal, bone marrow and cardiac transplantation.