The atrial high rate episode diagnostic in the Thera pacemaker reports frequency, duration, and date/time of atrial tachyarrhythmias according to programmed criteria. The aim of the study was to validate the atrial high rate episode diagnostic feature. Episodes of atrial fibrillation recorded by Holter monitoring were compared to episodes detected by the pacemaker. Forty five ambulatory (Holter) recordings were used for evaluation. Thirty of 45 ambulatory (Holter) recordings showed sinus rhythm. On 4 of these 30 ambulatory (Holter) recordings, the Thera detected 12 episodes of atrial tachyarrhythmias as false-positives (sinus rhythm was detected as atrial tachyarrhythmia). The main reason was far-field R and T was oversensing. On 15 of 45 ambulatory (Holter) recordings, 125 episodes of atrial tachyarrhythmias were recorded. Ninety-three of these events also were detected by the pacemaker, while for 32 events the Thera reported sinus rhythm. The main reason was that the episodes were of too short duration. Therefore, the Thera (programmed with detection rate 160 beats/min, detection beats 40, termination beats 10) was unable to detect atrial tachycardias. Software simulation of the diagnostic algorithm under several programming settings using the digitized Holter files demonstrated highly reliable detection of atrial tachyarrhythmias (sensitivity 98%, specificity 100%) when programmed as follows: detection rate 220 beats/min, detection beats 10, termination beats 20. It can be concluded that Thera's high rate episode monitor is a reliable tool for detection of atrial tachyarrhythmias, if programmed as recommended.

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The results of prospective noninvasive cardiologic investigations, including echocardiography and Holter monitoring are described in 2 siblings with juvenile ceroid lipofuscinosis of the Spielmeyer-Vogt-Sjogren type. In the elder patient, echocardiography revealed ventricular hypertrophy with slowed ventricular relaxation. Holter monitoring showed not only bradycardia but also slow and fast ectopic atrial rhythms, sinus arrests and complex ventricular ectopic activity including ventricular tachycardia. In the younger patient the findings were less severe. These functional disturbances due to cardiac involvement, never reported before in this disease, are discussed.

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Like ajmaline, procainamide can be used to identify patients with the Wolff-Parkinson-White syndrome who have a short refractory period of the accessory pathway in an anterograde direction. Procainamide given intravenously in a maximal dose of 10 mg/kg body weight over a 5 minute period during sinus rhythm produced complete anterograde block in the accessory pathway in 20 of 39 patients. An electrophysiologic investigation performed 24 to 48 hours later revealed that in 19 of the 20 patients the effective refractory period of the accessory pathway was 270 ms or greater. In 18 of the 19 patients not exhibiting anterograde block in the accessory pathway, the refractory period was less than 270 ms. When ajmaline was compared with procainamide in the same patients, 100 mg of procainamide had approximately the same effect as 10 mg of ajmaline. The use of intravenous procainamide is a reliable and rapid method of identifying patients with the Wolff-Parkinson-White syndrome who may be at risk for circulatory insufficiency or sudden death in case of atrial fibrillation.