Relationship Between Atrioventricular Delay and Oxygen Consumption in Patients with Sick Sinus Syndrome: Relevance to Rate Responsive Pacing

To develop a dromotropic-controlled rate adaptive algorithm for patients with sick sinus syndrome (SSS) and intact AV conduction, 14 pace-maker patients with SSS underwent cardiopulmonary exercise testing (CPX). During exercise, the pace-maker was programmed in an AAT mode without rate adaptation, whereby 3 patients developed supraventricular arrhythmia and 11 patients kept sinus rhythm. Chronotropic incompetence (CI) at heart rate (HR) < 95 beats/min at the anaerobic threshold (AT) was found in five patients. In patients with chronotropic competence (CC), the HR increase was significantly greater than in CI patients (rest: 73.2 +/- 12.6 vs. 64.2 +/- 4.0 beats/min;AT:101.2 +/- 6.2 vs. 82.0 +/- 5.1 beats/min;peak: 135.2 +/- 10.7 vs. 103.2 +/- 10.9 beats/min). There was no significant difference in the AVD between CC and CI patients (rest: 167.7 +/- 38.6 vs. 170.8 +/- 22.5 ms, AT: 156.2 +/- 30.7 vs. 163.6 +/- 21.6 ms, peak: 144.7 +/- 29.0 vs. 152.4 +/- 15.0 ms). The correlation coefficient between HR increase and VO2 was +1.0 and between AVD decrease and VO2 - 1.0 in both groups. An increase in pacing rate from 75 beats/min to 120 beats/min without exercise (overpacing) led to a prolongation of the AV interval of about 30.6 +/- 14.2 ms. Based on this closed loop control with negative feedback, a dromotropic rate adaptive algorithm for patients with SSS and intact AV conduction could be developed.     

Preoperative diagnosis of primary carcinoma of the fallopian tube

Two instances of primary carcinoma of the Fallopian tube, the diagnosis of both of which was made preoperatively on the basis of inexplicable postmenopausal metrorrhagia, are herewith reported.     

AN OPTICAL CLASSIFICATION OF KERATOCONUS A PRELIMINARY REPORT*

The paper describes a procedure utilizing a modified biomicroscope and corneal toposcope for the objective determination of the physical parameters of the corneal cone (horizontal cone width and sagittal depth) and the development of a classification of the condition based on comparative ratios of the obtained data. The paper initially describes some existing classifications based on: (a) photo-keratoscopic findings: (b) correlation of the disease stage to visual acuity; (c) observable corneal changes associated with the disease severity; and (d) sequential studies utilizing an electron microscope. The paper then describes the research plan with emphasis on the specific instrumentation utilized and the types of data obtained. A discussion is presented of Lindstedt's device as altered by Stenström, and a procedure noted for the approximate alignment of the target on the corneal apex. By virtue of the methods described, it is felt that the practitioner will have the means to detect more accurately and chart the course of the keratonic condition.