There is a strong association between non-accidental falls and cardioinhibitory CSH. These patients would not usually be referred for cardiovascular assessment. Carotid sinus hypersensitivity should be considered in all older adults who have non-accidental falls.

SUMMARY To assess the influence of diurnal changes in the autonomic nervous system on the QT interval, 24 hour dynamic electrocardiographic monitoring was performed in six-pacemaker dependent patients with normally innervated hearts, in six cardiac transplant patients with anatomically denervated hearts (but which respond to circulating catecholamines), and in nine diabetic patients with confirmed autonomic neuropathy. QT and RR intervals from hourly intervals were measured and Bazett's formula was used to correct QT intervals during sinus rhythm. All

Objectives: While carotid sinus syndrome (CSS) is traditionally defined by the association of carotid sinus hypersensitivity (CSH) with syncope, uncertainty remains over the role, if any, of complex pacing in patients with CSH and unexplained or recurrent falls. We sought to clarify the role of dual chamber pacing in this patient group in the first placebo-controlled study in CSH. Design: Randomised, double-blind, crossover, placebocontrolled trial. Setting: Specialist falls and syncope facility. Patients: Consecutive subjects aged over 55 years with CSH as the sole attributable cause of three or more unexplained falls in the 6 months preceding enrolment. Intervention: Dual-chamber permanent pacing with ratedrop response programming. The pacemaker was switched on (DDD/RDR) or off (ODO (placebo)) for 6 months, then crossed over to the alternate mode for a further 6 months, in randomised, double-blind fashion. Main outcome measure: The primary outcome measure was number of falls in paced and non-paced modes. Results: Twenty-five of 34 subjects (mean 76.8 years (SD 9.0), 27 (79%) female) recruited completed the study. Pacing intervention had no effect on number of falls (4.04 (9.54) in DDD/RDR mode, 3.48 (7.22) in ODO; relative risk of falling in ODO mode 0.82, 95% CI 0.62 to 1.10). Conclusion: Permanent pacing intervention had no effect on fall rates in older patients with CSH. Further work is urgently needed to clarify the role, if any, of complex pacing in this patient group.

Background-Pacemaker pocket infection is a potentially serious problem after permanent pacemaker implantation. Antibiotic prophylaxis is commonly prescribed to reduce the incidence of this complication, but current trial evidence of its efficacy is conflicting. A large prospective randomised trial was therefore performed of antibiotic prophylaxis in permanent pacemaker implantation. The intention was firstly to determine whether antibiotic prophylaxis is efficacious in these patients and secondly to identify which patients are at the highest risk of infection. Methods-A prospective randomised open trial of flucloxacillin (clindamycin if the patient was allergic to penicillin) v no antibiotic was performed in a cohort of patients undergoing first implantation of a permanent pacing system over a 17 month period. Intravenous antibiotics were started at the time of implantation and continued for 48 hours. The trial endpoint was a repeat operation for an infective complication. Results-473 patients were entered into a randomised trial. 224 received antibiotic prophylaxis and 249 received no antibiotics. A further 183 patients were not randomised but were treated according to the operator's preference (64 antibiotics, 119 no antibiotics); these patients are included only in the analysis of predictors ofinfection. Patients were followed up for a mean (SD) of 19(5) months. Among the patients in the randomised group there were nine infections requiring a repeat operation, all in the group not receiving antibiotic (P = 0.003). In the total patient cohort there were 13 infections, all but one in the non-antibiotic group (P = 0.006).

To study the prevalence of Cardioinhibitory Carotid Sinus Hypersensitivity (CICSH) in patients 50 years or over presenting to casualty with "unexplained" or "recurrent" falls. The prospective study was from October 1, 1995 to April 30, 1996 in the Inner City Accident and Emergency Departments, Newcastle Upon Tyne, U.K. Ten thousand four hundred forty-three patients 50 years and over presented, of which 4,051 (39%) were fallers. Fallers were excluded if they lived over 15 miles from the hospital (81), were registered blind (17), were unable to speak English (22), were unable to previously walk (27), if there was a history of only one accidental fall (1,659) or were cognitively impaired (776: Mini Mental State Examination < 24 [30]) or if there was a clear attributable medical diagnosis for the fall (871). Five hundred ninety-eight "unexplained" or "recurrent" fallers (defined as three or more falls in the previous 12 months) were assessed for carotid sinus massage (CSM). One hundred forty-five patients declined CSM (24%), 70 (12%) had relative contraindications to CSM and 13 already had pacemakers in situ (2%). Two hundred seventy-nine underwent CSM, of whom 65 had CICSH (23%), which might be amenable to treatment with pacemakers. The prevalence of CICSH (a potentially treatable condition) in "unexplained" or "recurrent" fallers who present to the accident and emergency department is 23%. A randomized control study to assess benefit from pacemaker intervention in these patients is underway.